WorldWideScience

Sample records for ash particle deposition

  1. Development of an ash particle deposition model considering build-up and removal mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Strandstroem, Kjell; Mueller, Christian; Hupa, Mikko [Aabo Akademi Process Chemistry Centre, Biskopsgatan 8, FI-20500 Aabo (Finland)

    2007-12-15

    Slagging and fouling on heat exchanger surfaces in power boilers fired with fossil fuels and fuel mixtures has a significant influence on boiler efficiency and availability. Mathematical modelling is since long considered a suitable method to assist boiler operators to determine optimized operating conditions for an existing furnace. The ultimate goal in ash deposition prediction is hereby the determination of the total amount of material deposited and hence the determination of the total reduction in efficiency. Depending on the fuels fired the total deposited mass is a combination of ash particle deposition and ash particle erosion due to non-sticky particles. The novel ash particle deposition model presented in this work considers deposition of sticky ash particles, cleansing of deposit by non-sticky sand particles and sticking of sand due to contact with sticky ash. The steady-state modelling results for the total amount of ash deposited on the deposition probe of an entrained flow reactor presented in this work agree well with the experimental data. Only at very high fractions of sand added as non-sticky material, a significant influence of the sand on the overall mass deposited was found. Since the model considers sticking of non-sticking sand due to contact with sticky ash, the fraction of sand deposited on the probe was especially studied. Using a correction factor to consider the influence of operating time on the steady-state simulations led to good agreement between simulations and experimental data. (author)

  2. Development of an ash particle deposition model considering build-up and removal mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kjell Strandstroem; Christian Muellera; Mikko Hupa [Abo Akademi Process Chemistry Centre, Abo (Finland)

    2007-12-15

    Slagging and fouling on heat exchanger surfaces in power boilers fired with fossil fuels and fuel mixtures has a significant influence on boiler efficiency and availability. Mathematical modelling has long been considered a suitable method to assist boiler operators to determine optimized operating conditions for an existing furnace. The ultimate goal in ash deposition prediction is hereby the determination of the total amount of material deposited and hence the determination of the total reduction in efficiency. Depending on the fuels fired the total deposited mass is a combination of ash particle deposition and ash particle erosion due to non-sticky particles. The novel ash particle deposition model presented in this work considers deposition of sticky ash particles, cleansing of deposit by non-sticky sand particles and sticking of sand due to contact with sticky ash. The steady-state modelling results for the total amount of ash deposited on the deposition probe of an entrained flow reactor presented in this work agree well with the experimental data. Only at very high fractions of sand added as non-sticky material, a significant influence of the sand on the overall mass deposited was found. Since the model considers sticking of non-sticking sand due to contact with sticky ash, the fraction of sand deposited on the probe was especially studied. Using a correction factor to consider the influence of operating time on the steady-state simulations led to good agreement between simulations and experimental data. 12 refs., 10 figs.

  3. Shedding of ash deposits

    DEFF Research Database (Denmark)

    Zbogar, Ana; Frandsen, Flemming; Jensen, Peter Arendt

    2009-01-01

    Ash deposits formed during fuel thermal conversion and located on furnace walls and on convective pass tubes, may seriously inhibit the transfer of heat to the working fluid and hence reduce the overall process efficiency. Combustion of biomass causes formation of large quantities of troublesome...... ash deposits which contain significant concentrations of alkali, and earth-alkali metals. The specific composition of biomass deposits give different characteristics as compared to coal ash deposits, i.e. different physical significance of the deposition mechanisms, lower melting temperatures, etc....... Low melting temperatures make straw ashes especially troublesome, since their stickiness is higher at lower temperatures, compared to coal ashes. Increased stickiness will eventually lead to a higher collection efficiency of incoming ash particles, meaning that the deposit may grow even faster...

  4. Application of spherical fly-ash particles to study spatial deposition of atmospheric pollutants in northen-eastern Estonia

    International Nuclear Information System (INIS)

    Alliksaar, T.

    2000-01-01

    Spherical fly-ash particles, emitted to the atmosphere in the high-temperature combustion process of fossil fuels, were found in considerable amounts in analysed snow samples of north-eastern Estonia. Spatial deposition of particles in snow cover is compared with the results of surface sediment samples of lakes. The results from snow characterise well the distribution of pollution sources and the distance from the main power plants in north eastern Estonia. Variations in particle deposition of closely situated snow samples were found to be negligible. Fly-ash particle influxes in snow samples correlate well with modelled maximum concentration fields of flyash in the near-surface air layer. (author)

  5. Ash formation and deposition in coal and biomass fired combustion systems: Progress and challenges in the field of ash particle sticking and rebound behavior

    DEFF Research Database (Denmark)

    Kleinhans, Ulrich; Wieland, Christoph; Frandsen, Flemming J.

    2018-01-01

    . The impaction of solid, molten or partially molten particles on surfaces is dependent on the particle and surface characteristics. For instance, a particulate deposit might capture incoming particles or be removed due to erosion, while a molten layer will collect all impacting particles, no matter...... if they are sticky or not. The main properties affecting the particle stickiness are the viscosity and surface tension for silicate-rich ashes. On the contrary, the stickiness of salt-rich ashes – typical for herbaceous biomass and wood- or waste-based fuels – is often described using the liquid melt fraction......, their required parameters are discussed and typical particle and surface properties found in combustion systems, are summarized. Eight different sticking criteria are implemented in a computational fluid dynamics code and computations are compared against measurements from an entrained flow reactor. Uniform...

  6. Formation, Sintering and Removal of Biomass Ash Deposits

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi

    conditions in laboratory-scale setups. Deposit formation was simulated in an Entrained Flow Reactor, to investigate the effect of operating conditions and ash chemistry on the rate of deposit formation. Experiments were performed using model biomass fly ash, prepared from mixtures of K2Si4O9, KCl, K2SO4, Ca....... Moreover, biomass ash deposits may cause severe corrosion of boiler surfaces. Therefore, reducing deposit formation and timely deposit removal are essential for optimal boiler operation. The formation, sintering and removal of boiler deposits has been investigated in this PhD project, by simulating boiler...... temperature increased the sticking probability of the fly ash particles/deposit surface, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, it was observed...

  7. Adhesion Strength of Biomass Ash Deposits

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Jensen, Peter Arendt; Wu, Hao

    2016-01-01

    . Therefore, timely removal of ash deposits is essential for optimal boiler operation. In order to improve the qualitative and quantitative understanding of deposit shedding in boilers, this study investigates the shear adhesion strength of biomass ash deposits on superheater tubes. Artificial biomass ash...... deposits were prepared on superheater tubes and sintered in an oven at temperatures up to 1000 °C. Subsequently, the deposits were sheared off by an electrically controlled arm, and the corresponding adhesion strength was measured. The results reveal the effect of temperature, ash/deposit composition......, sintering duration, and steel type on the adhesion strength....

  8. Prediction of ash deposition using CFD simulation combined to thermodynamic calculation

    Energy Technology Data Exchange (ETDEWEB)

    Takeshi Muratani; Takashi Hongo [UBE Industries, Ltd., Yamaguchi (Japan). Coal Department, Energy and Environment Division

    2007-07-01

    This study focused on the advanced ash deposition prediction using computational fluid dynamics (CFD) analysis combined to thermodynamic calculation, considering both combustion characteristics and ash fusibility. Combustion field in pulverised coal-fired boiler was calculated through the normal CFD process. As the post process of combustion calculation, ash particles were injected into the combustion field to calculate ash deposition by CFD, in which particle sticking sub-program was newly employed. In this post process, ash deposition condition for CFD calculation was defined with the ash fusibility data obtained from thermodynamic analysis. These results of ash deposition on the furnace wall showed good agreement with the plant observation. Furthermore, in order to improve the plant operation, some virtual cases were simulated, which might reduce ash deposition. 7 refs., 14 figs., 6 tabs.

  9. Adhesion Strength of Biomass Ash Deposits

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Jensen, Peter Arendt; Wu, Hao

    2015-01-01

    This study investigates the shear adhesion strength of biomass ash deposits on superheater tubes. Artificial biomass ash deposits were prepared on superheater tubes and sintered in an oven at temperatures up to 1000°C. Subsequently, the deposits were sheared off with the help of an electrically...... controlled arm. Higher sintering temperatures resulted in greater adhesion strengths, with a sharp increase observed near the melting point of the ash. Repetition of experiments with fixed operation conditions revealed considerable variation in the obtained adhesion strengths, portraying the stochastic...

  10. The heterogeneous nature of mineral matter, fly-ash and deposits

    Energy Technology Data Exchange (ETDEWEB)

    Creelman, R.A.; Pohl, J.H.; Devir, G.P.; Su, S. [R.A. Creelman and Associates, Epping, NSW (Australia)

    2000-07-01

    This paper reports on a series of slagging studies investigating the heterogeneous nature of mineral matter, fly ash and deposits, and how this heterogeneity affects deposition. The data come from low temperature ashing (LTA) of pulverised coal, fly ash from boilers, and deposits from pilot-scale furnaces and boilers. The paper presents optical and scanning electron (SEM) micrographs, electron microprobe analysis (EMPA) and energy dispersive x-ray analysis (EDXRA) of mineral matter, individual fly ash particles, and localised regions of deposits. During combustion, the included mineral matter is transformed into fly ash, melts and partially adheres to the char surface, and may form agglomerated masses. Excluded mineral matter has little chance of encountering another ash particle and agglomerating in the gas phase, but can react with other particles in the wall deposits. Certain fly ash particles adhere to the wall where they can combine with other fly ash particles. Analyses of molten regions of deposits have shown, so far, four mineral phase fields to be responsible for forming difficult deposits with melting points below deposit surface temperatures of 1200 to 1350{sup o}C. These mineral fields include iron cordierite, albite and its silica undersaturated equivalent nepheline, anorthite, and compounds with ratios of Ca to P of 2.3-2.5.

  11. Ash fusion temperatures and the transformations of coal ash particles to slag

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, S.K.; Wall, T.F.; Creelman, R.A.; Gupta, R.P. [University of Newcastle, Newcastle, NSW (Australia). CRC for Black Coal Utilisation

    1998-07-01

    A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600{degree}C. The temperature corresponding to the rapid rate of shrinkage correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined using a scanning electron microscope (SEM) to identify the associated chemical and physical changes. The progressive changes in the range of chemical composition (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenisation, viscosity and ash fusion mechanisms. Alternate ash fusion temperatures based on different levels of shrinkage have also been suggested to characterise the ash deposition tendency of the coals. 13 refs., 9 figs.

  12. Hydraulics of subaqueous ash flows as deduced from their deposits

    Science.gov (United States)

    Doronzo, Domenico M.; Dellino, Pierfrancesco

    2012-09-01

    Subaqueous ash flows are gravity currents consisting of a mixture of sea water and ash particles. Also called volcaniclastic turbidity currents (VTCs), they can be generated because of remobilization of pyroclastic fall deposits, which are emplaced into the sea around a volcanic island, as well as far away, during an explosive eruption. The VTC upper part is the turbulent transport system for the flow, whereas the viscous basal one is the depositional system. Typical sequences of VTC deposits are characterized by cross-laminations, planar and convolute laminations, and massive beds, which reflect the stratified nature of the flow. Here, the analysis of some VTC hydraulic parameters is presented in order to depict flow behavior and sedimentation during deposition. A reverse engineering approach is proposed, which consists of calculating hydraulic parameters by starting from deposit features. The calculated values show that a VTC is homogeneously-turbulent for most of the thickness, but is viscous at its base. First, cross-laminations are directly acquired over the rough pre-existing seafloor, then planar or convolute laminations aggrade over the newly formed substrate. Finally, fine-grained suspended particles gently settle and cap the flow deposit.

  13. Ash fusion temperatures and their association with the transformations of coal ash particles to slag

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, S.K.; Wall, T.F.; Gupta, R.P. [Cooperative Research Centre for Black Coal Utilisation, Newcastle, NSW (Australia); Creelman, R.A. [Creelman (R.A.) and Associates, Sydney, NSW (Australia)

    1997-04-01

    Ash deposition on furnace walls in PF (pulverized fuel) furnaces is called slagging when it occurs in the high temperature areas of furnaces directly exposed to flame radiation and fouling in other regions such as tubes in the convection section of the boiler. There are well documented shortcomings of certain approaches relating to their uncertainties as predictive tools for plant performance such as poor repeatability and re-producibility of ash fusion measurements. The nature of physical and chemical changes occurring during melting of coal ash has been investigated in the current study to provide an alternative procedure to the ash fusion test. Shrinkage measurements are frequently used in metallurgy and ceramic science to study the physical properties of materials at high temperatures. The output of this experiment provides three to four `peaks` (maximum rate of shrinkage with temperature) of different intensity and at different temperatures which are related to melting characteristics of the sample. It was concluded that shrinkage extents exceeding 50 percent indicated that the effect of the ash particle size is of secondary importance compared to ash chemistry in determining shrinkage levels, with fine particles giving rapid shrinkage events 10 degrees C lower in temperature. (author). 7 figs., refs.

  14. CFD simulation of ash deposit formation in fixed bed biomass furnaces and boilers

    NARCIS (Netherlands)

    Forstner, M.; Hofmeister, G.; Joeller, M.; Dahl, J.; Braun, M.; Kleditzsch, S.; Scharler, R.; Obernberger, I.

    2006-01-01

    In order to describe and predict the formation of ash deposits in biomass fired combustion plants, a mathematical model is being developed and implemented into the CFD code Fluent¿ as a post processing tool. At the present state of development the model covers the release of coarse ash particles and

  15. Composition and microstructure of a furnace ash deposit from a coal-fired utility boiler

    Energy Technology Data Exchange (ETDEWEB)

    Fessler, R R

    1980-07-01

    An exploratory study of the structure and composition of furnace-ash deposits was carried out using optical metallography, electron microprobe analysis, scanning electron microscopy, and energy-dispersive X-ray analysis. The results of these analyses were supplemented by studies of particulate melting temperature using hot-stage microscopy to measure melting temperature, and energy-dispersive X-ray analyses to measure composition of melted particles. It was found that the general structure of the ash deposit was a matrix of glassy, spherical particles having a wide range of composition in which unfused particles containing iron oxide and calcium oxide were dispersed. At the imprint of the tube surface a considerable concentration of calcium, sulphur and iron was found. Near the fused outer surface of the deposit, the glassy materials had melted into a porous, glassy slag containing spherical globules of iron oxide combined with other materials. There were no systematic compositional gradients from the tube surface to the fused outer layer except for the sulfur layer found only at the tube surface. However, there were significant differences in composition from particle to particle and these differences were similar to those found in the coal mineral matter as isolated by low-temperature ashing. Single particles of low-temperature ash were found having low fusion temperatures, in the range of fusion temperatures for particles in furnance has. Thus, the glassy spheres found in furnace deposits could originate from single coal particles, without the need of interactions among coal particles or ash particles.

  16. Deposition behaviour of model biofuel ash in mixtures with quartz sand. Part 1: Experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Mischa Theis; Christian Mueller; Bengt-Johan Skrifvars; Mikko Hupa; Honghi Tran [Aabo Akademi Process Chemistry Centre, Aabo (Finland). Combustion and Materials Chemistry

    2006-10-15

    Model biofuel ash of well-defined size and melting properties was fed into an entrained flow reactor (EFR) to simulate the deposition behaviour of commercially applied biofuel mixtures in large-scale boilers. The aim was to obtain consistent experimental data that can be used for validation of computational fluid dynamics (CFD)-based deposition models. The results showed that while up to 80 wt% of the feed was lost to the EFR wall, the composition of the model ash particles collected at the reactor exit did not change. When model ashes were fed into the reactor individually, the ash particles were found to be sticky when they contained more than 15 wt% molten phase. When model ashes were fed in mixtures with silica sand, it was found that only a small amount of sand particles was captured in the deposits; the majority rebounded upon impact. The presence of sand in the feed mixture reduced the deposit buildup by more than could be expected from linear interpolation between the model ash and the sand. The results suggested that sand addition to model ash may prevent deposit buildup through erosion. 22 refs., 6 figs., 3 tabs.

  17. COAL-FIRED UTILITY BOILERS: SOLVING ASH DEPOSITION PROBLEMS; TOPICAL

    International Nuclear Information System (INIS)

    Christopher J. Zygarlicke; Donald P. McCollor; Steven A. Benson; Jay R. Gunderson

    2001-01-01

    The accumulation of slagging and fouling ash deposits in utility boilers has been a source of aggravation for coal-fired boiler operators for over a century. Many new developments in analytical, modeling, and combustion testing methods in the past 20 years have made it possible to identify root causes of ash deposition. A concise and comprehensive guidelines document has been assembled for solving ash deposition as related to coal-fired utility boilers. While this report accurately captures the current state of knowledge in ash deposition, note that substantial research and development is under way to more completely understand and mitigate slagging and fouling. Thus, while comprehensive, this document carries the title ''interim,'' with the idea that future work will provide additional insight. Primary target audiences include utility operators and engineers who face plant inefficiencies and significant operational and maintenance costs that are associated with ash deposition problems. Pulverized and cyclone-fired coal boilers are addressed specifically, although many of the diagnostics and solutions apply to other boiler types. Logic diagrams, ash deposit types, and boiler symptoms of ash deposition are used to aid the user in identifying an ash deposition problem, diagnosing and verifying root causes, determining remedial measures to alleviate or eliminate the problem, and then monitoring the situation to verify that the problem has been solved. In addition to a step-by-step method for identifying and remediating ash deposition problems, this guideline document (Appendix A) provides descriptions of analytical techniques for diagnostic testing and gives extensive fundamental and practical literature references and addresses of organizations that can provide help in alleviating ash deposition problems

  18. Atmospheric fate and transport of fine volcanic ash: Does particle shape matter?

    Science.gov (United States)

    White, C. M.; Allard, M. P.; Klewicki, J.; Proussevitch, A. A.; Mulukutla, G.; Genareau, K.; Sahagian, D. L.

    2013-12-01

    velocimetry (PIV). Scanning Electron Microscopy (SEM) of ash particles collected in localized deposition areas is used to correlate the PIV results to particle shape. In addition, controlled wind tunnel experiments are used to determine particle fate and transport in a turbulent boundary layer for a mixed particle population. Collectively, these studies will provide an improved understanding of the effects of particle shape on sedimentation and dispersion, and foundational data for the predictive modeling of the fate and transport of fine ash particles suspended in the atmosphere.

  19. Bubbles and Dust: Dissolution Rates of Unhydrated Volcanic Ash as a Function of Morphology, Composition, and Particle Size

    Science.gov (United States)

    Wygel, C. M.; Sahagian, D. L.

    2017-12-01

    Volcanic eruptions are natural hazards due to their explosive nature and widespread transportation and deposition of ash particles. After deposition and subsequent leaching in soils or water bodies, ash deposition positively (nutrients) and negatively (contaminants) impacts the health of flora and fauna, including humans. The effects of ash leachates have been difficult to replicate in field and laboratory studies due to the many complexities and differences between ash particles. Ash morphology is characteristic for each eruption, dependent upon eruption energy, and should play a critical role in determining leaching rates. Morphology reflects overall particle surface area, which is strongly influenced by the presence of surface dust. In addition, ash composition, which in part controls morphology and particle size, may also affect leaching rates. This study determines the extent to which ash morphology, surface area, composition, and particle size control ash dissolution rates. Further, it is necessary to determine whether compound vesicular ash particles permit water into their interior structures to understand if both the internal and external surface areas are available for leaching. To address this, six fresh, unhydrated ash samples from diverse volcanic environments and a large range in morphology, from Pele's spheres to vesicular compound ash, are tested in the laboratory. Ash morphology was characterized on the Scanning Electron Microscope (SEM) before and after leaching and surface area was quantified by Brunauer Emmett Teller (BET) analysis and with geometric calculations. Column Leachate Tests (CLT) were conducted to compare leaching rates over a range of basaltic to silicic ashes as a function of time and surface area, to recreate the effects of ash deposition in diverse volcanic environments. After the CLT, post-leaching water analyses were conducted by Ion Coupled Plasma-Mass Spectrometry (ICP-MS) and Ion Chromatography (IC). We find that leaching

  20. Stabilization of Fly Ash Deposits through Selected Cereal Crops

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2012-10-01

    Full Text Available Fly ash, a waste product from burning coal in power plants, occupies important spaces and is a major harm forenvironment: water, air, soil and associated ecosystems. New deposits do not have available nutrients for plantgrowth. The study presents a process of stimulating growth of oats in deposits of fly ash, which eliminates listed.Phytostabilization of new deposit is fast after fertilization with sewage sludge-based compost in the presence/absence of native or modified volcanic tuff with grain species, Avena sativa L., and variety Lovrin 1. Experimentalstudies have shown the species adaptability to climatic conditions and a growth rate until the maturity correlated withtype of treatment of upper layers of fly ash deposit. Fly ash with sewage sludge compost treatment 50 t/hadetermined the growth with 75% of the amount of grains vs. the amount of grains harvested from untreated fly ash.Fly ash with sewage sludge compost mixed with modified indigenous volcanic tuff 2.5 t/ha treatment determined thegrowth with 80% vs. the amount of grains harvested from untreated fly ash. If oat straw harvested from fertilizedvariant without modified indigenous volcanic tuff increases in weight are 30% and for fertilized variant in thepresence of tuff increases in weight are 39.8% vs. quantities harvested from untreated fly ash.

  1. Ash Deposition Trials at Three Power Stations in Denmark

    DEFF Research Database (Denmark)

    Laursen, Karin; Frandsen, Flemming; Larsen, Ole Hede

    1998-01-01

    Six full-scale trials were conducted at three power stations in Denmark: Ensted, Funen, and Vendsyssel power stations. During these trials, pulverized coal, bottom ash, fly ash, and deposits from cooled probes were sampled and analyzed with various techniques. On the basis of SEM analyses...

  2. Phenolic acids as bioindicators of fly ash deposit revegetation

    Energy Technology Data Exchange (ETDEWEB)

    L. Djurdjevic; M. Mitrovic; P. Pavlovic; G. Gajic; O. Kostic [Institute for Biological Research ' Sinisa Stankovic,' Belgrade (Serbia and Montenegro). Department of Ecology

    2006-05-15

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the 'Nikola Tesla-A' thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges. Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  3. Geotechnical properties of ash deposits near Hilo, Hawaii

    Science.gov (United States)

    Wieczorek, G.F.; Jibson, R.W.; Wilson, R.C.; Buchanan-Banks, J. M.

    1982-01-01

    Two holes were hand augered and sampled in ash deposits near Hilo, Hawaii. Color, water content and sensitivity of the ash were measured in the field. The ash alternated between reddish brown and dark reddish brown in color and had water contents as high as 392%. A downhole vane shear device measured sensitivities as high as 6.9. A series of laboratory tests including grain size distribution, Atterberg limits, X-ray diffraction analysis, total carbon determination, vane shear, direct shear and triaxial tests were performed to determine the composition and geotechnical properties of the ash. The ash is very fine grained, highly plastic and composed mostly of gibbsite and amorphous material presumably allophane. The ash has a high angle of internal friction ranging from 40-43? and is classified as medium to very sensitive. A series of different ash layers was distinguished on the basis of plasticity and other geotechnical properties. Sensitivity may be due to a metastable fabric, cementation, leaching, high organic content, and thixotropy. The sensitivity of the volcanic ash deposits near Hilo is consistent with documented slope instability during earthquakes in Hawaii. The high angles of internal friction and cementation permit very steep slopes under static conditions. However, because of high sensitivity of the ash, these slopes are particularly susceptible to seismically-induced landsliding.

  4. Lake-sediment record of PAH, mercury, and fly-ash particle deposition near coal-fired power plants in Central Alberta, Canada.

    Science.gov (United States)

    Barst, Benjamin D; Ahad, Jason M E; Rose, Neil L; Jautzy, Josué J; Drevnick, Paul E; Gammon, Paul R; Sanei, Hamed; Savard, Martine M

    2017-12-01

    We report a historical record of atmospheric deposition in dated sediment cores from Hasse Lake, ideally located near both currently and previously operational coal-fired power plants in Central Alberta, Canada. Accumulation rates of spheroidal carbonaceous particles (SCPs), an unambiguous marker of high-temperature fossil-fuel combustion, in the early part of the sediment record (pre-1955) compared well with historical emissions from one of North America's earliest coal-fired power plants (Rossdale) located ∼43 km to the east in the city of Edmonton. Accumulation rates in the latter part of the record (post-1955) suggested inputs from the Wabamun region's plants situated ∼17-25 km to the west. Increasing accumulation rates of SCPs, polycyclic aromatic hydrocarbons (PAHs) and Hg coincided with the previously documented period of peak pollution in the Wabamun region during the late 1960s to early 1970s, although Hg deposition trends were also similar to those found in western North American lakes not directly affected by point sources. A noticeable reduction in contaminant inputs during the 1970s is attributed in part to technological improvements and stricter emission controls. The over one hundred-year historical record of coal-fired power plant emissions documented in Hasse Lake sediments has provided insight into the impact that both environmental regulations and changes in electricity output have had over time. This information is crucial to assessing the current and future role of coal in the world's energy supply. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  5. Characteristic fly-ash particles from oil-shale combustion found in lake sediments

    International Nuclear Information System (INIS)

    Alliksaar, T.; Hoerstedt, P.; Renberg, I.

    1998-01-01

    Fly-ash particles accumulate in sediments and can be used to assess spatial distribution and temporal trends of atmospheric deposition of pollutants derived from high temperature combustion of fossil fuels. Previous work has concerned fly-ash derived from oil and coal. Oil-shale is the main fossil fuel used in Estonia and a major source of atmospheric pollution in the Baltic states. To assess if oil-shale power plants produce specific fly-ash particles scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to compare fly-ash particles from oil-shale combustion with particles from oil and coal combustion. Two types were analysed, large black (10-30μm) and small glassy (< 5 μm) spheroidal particles. Although article morphology to some extent is indicative of the fuel burnt, morphological characters are not sufficient to differentiate between particles of different origin. However, the results indicate that with EDX analysis the fly-ash from oil-shale can be distinguished form oil and coal derived particles in environmental samples. Concentrations of large black and small glassy spheroidal fly-ash particles in a sediment core from an Estonian lake showed similar trends to oil-shale combustion statistics from Estonian power plants. 27 refs., 6 figs., 2 tabs

  6. Phenolic acids as bioindicators of fly ash deposit revegetation.

    Science.gov (United States)

    Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

    2006-05-01

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  7. Size limits for rounding of volcanic ash particles heated by lightning

    Science.gov (United States)

    Wadsworth, Fabian B.; Vasseur, Jérémie; Llewellin, Edward W.; Genareau, Kimberly; Cimarelli, Corrado; Dingwell, Donald B.

    2017-03-01

    Volcanic ash particles can be remelted by the high temperatures induced in volcanic lightning discharges. The molten particles can round under surface tension then quench to produce glass spheres. Melting and rounding timescales for volcanic materials are strongly dependent on heating duration and peak temperature and are shorter for small particles than for large particles. Therefore, the size distribution of glass spheres recovered from ash deposits potentially record the short duration, high-temperature conditions of volcanic lightning discharges, which are hard to measure directly. We use a 1-D numerical solution to the heat equation to determine the timescales of heating and cooling of volcanic particles during and after rapid heating and compare these with the capillary timescale for rounding an angular particle. We define dimensionless parameters—capillary, Fourier, Stark, Biot, and Peclet numbers—to characterize the competition between heat transfer within the particle, heat transfer at the particle rim, and capillary motion, for particles of different sizes. We apply this framework to the lightning case and constrain a maximum size for ash particles susceptible to surface tension-driven rounding, as a function of lightning temperature and duration, and ash properties. The size limit agrees well with maximum sizes of glass spheres found in volcanic ash that has been subjected to lightning or experimental discharges, demonstrating that the approach that we develop can be used to obtain a first-order estimate of lightning conditions in volcanic plumes.

  8. Tensile Adhesion Strength of Biomass Ash Deposits: Effect of the Temperature Gradient and Ash Chemistry

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Nair, Akhilesh Balachandran; Jensen, Peter Arendt

    2018-01-01

    Replacing coal with biomass in power plants is a viable option for reducing net CO2 emissions and combating climate change. However, biomass combustion in boilers may exacerbate problems related to ash deposition and corrosion, demanding effective deposit removal. The tensile adhesion strength...

  9. Ash formation, deposition, corrosion, and erosion in conventional boilers

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.A.; Jones, M.L. [Univ. of North Dakota, Grand Forks, ND (United States)

    1995-12-01

    The inorganic components (ash-forming species) associated with coals significantly affect boiler design, efficiency of operation, and lifetimes of boiler parts. During combustion in conventional pulverized fuel boilers, the inorganic components are transformed into inorganic gases, liquids, and solids. This partitioning depends upon the association of the inorganic components in the coal and combustion conditions. The inorganic components are associated as mineral grains and as organically associated elements, and these associations of inorganic components in the fuel directly influence their fate upon combustion. Combustion conditions, such as temperature and atmosphere, influence the volatility and the interaction of inorganic components during combustion and gas cooling, which influences the state and size composition distribution of the particulate and condensed ash species. The intermediate species are transported with the bulk gas flow through the combustion systems, during which time the gases and entrained ash are cooled. Deposition, corrosion, and erosion occur when the ash intermediate species are transported to the heat-transfer surface, react with the surface, accumulate, sinter, and develop strength. Research over the past decade has significantly advanced understanding of ash formation, deposition, corrosion, and erosion mechanisms. Many of the advances in understanding and predicting ash-related issues can be attributed to advanced analytical methods to determine the inorganic composition of fuels and the resulting ash materials. These new analytical techniques have been the key to elucidation of the mechanisms of ash formation and deposition. This information has been used to develop algorithms and computer models to predict the effects of ash on combustion system performance.

  10. Effect of interfacial properties on mechanical stability of ash deposit

    Directory of Open Access Journals (Sweden)

    A. Ontiveros-Ortega

    2016-04-01

    Full Text Available The paper presents a study on the cohesion of volcanic ash particles using surface free energy determination and zeta potential analyses. This is a subject of great interest in physical volcanology, as many researches on volcanic particle aggregation are frequently reported. In this case, special attention is paid to the role of structural or hydration forces between hydrophilic surfaces, which are a consequence of the electron-donor/electron-acceptor character of the interface. From this point of view, the results are potentially interesting as they could give valuable insights into this process. The results are presented in terms of the total energy of interaction between dispersed particles, computed from the extended DLVO theory. Contributions to the total free energy of interaction were determined from the zeta potential and surface free energy of ash, measured under different experimental conditions. Two samples of basaltic volcanic ash (black and white with silica contents of 44% and 63% respectively are studied. The surface free energy and zeta potential were analysed for ashes immersed in different electrolytes (NaCl, CaCl2, FeCl3. The presence of electrolytes changes the surface properties of the solid materials. The analysis of total interaction energy between the ash particles in aqueous medium shows that soil cohesion strongly depends on ash surface properties, chemical nature, the adsorbed cation on the surface, and pH value.

  11. Particle deposition in ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)

    2002-09-01

    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the

  12. Constraining Diameters of Ash Particles in Io's Pele Plume by DSMC Simulation

    Science.gov (United States)

    McDoniel, William; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.

    2013-10-01

    The black “butterfly wings” seen at Pele are produced by silicate ash which is to some extent entrained in the gas flow from very low altitudes. These particles are key to understanding the volcanism at Pele. However, the Pele plume is not nearly as dusty as Prometheus, and these are not the only particles in the plume, as the SO2 in the plume will also condense as it cools. It is therefore difficult to estimate a size distribution for the ash particles by observation, and the drag on ash particles from the plume flow is significant enough that ballistic models are also of limited use. Using Direct Simulation Monte Carlo, we can simulate a gas plume at Pele which demonstrates very good agreement with observations. By extending this model down to nearly the surface of the lava lake, ash particles can be included in the simulation by assuming that they are initially entrained in the very dense (for Io) gas immediately above the magma. Particles are seen to fall to the ground to the east and west of the vent, agreeing with the orientation of the “butterfly wings”, and particles with larger diameters fall to the ground closer to the lava lake. We present a model for mapping simulated deposition density to the coloration of the surface and we use it to estimate the size distribution of ash particles in the plume.

  13. FALL3D: A computational model for transport and deposition of volcanic ash

    Science.gov (United States)

    Folch, A.; Costa, A.; Macedonio, G.

    2009-06-01

    FALL3D is a 3-D time-dependent Eulerian model for the transport and deposition of volcanic ashes and lapilli. The model solves the advection-diffusion-sedimentation (ADS) equation on a structured terrain-following grid using a second-order finite differences (FD) explicit scheme. Different parameterizations for the eddy diffusivity tensor and for the particle terminal settling velocities can be used. The code, written in FORTRAN 90, is available in both serial and parallel versions for Windows and Unix/Linux/Mac X operating systems (OS). A series of pre- and post-process utility programs and OS-dependent scripts to launch them are also included in the FALL3D distribution package. Although the model has been designed to forecast volcanic ash concentration in the atmosphere and ash loading at ground, it can also be used to model the transport of any kind of airborne solid particles. The model inputs are meteorological data, topography, grain-size distribution, shape and density of particles, and mass rate of particle injected into the atmosphere. Optionally, FALL3D can be coupled with the output of the meteorological processor CALMET, a diagnostic model which generates 3-D time-dependent zero-divergence wind fields from mesoscale forecasts incorporating local terrain effects. The FALL3D model can be a tool for short-term ash deposition forecasting and for volcanic fallout hazard assessment. As an example, an application to the 22 July 1998 Etna eruption is also presented.

  14. Pena Blanca uranium deposits and ash-flow tuffs relationship

    International Nuclear Information System (INIS)

    Magonthier, M.

    1987-01-01

    The Pena Blanca uranium deposits (Chihuahua, Mexico) are associated with a Tertiary sequence of ash-flow tuffs. Stratigraphic control is dominant and uranium mineralization occurs in stratiform and fracture-controlled deposits within 44 My-old units: Nopal Rhyolite and Escuadra Rhyolite. These units consist of highly vapor-phase crystallized ash-flow tuffs. They contain sanidine, quartz and granophyric phenocrysts, and minor ferromagnesian silicates. Nopal and Escuadra units are high-silica alkali-rich rhyolites that have a primary potassic character. The trace-element chemistry shows high concentrations in U-Th-Rb-Cs and low contents in Ba-Sr-Eu. These chemical properties imply a genetic relationship between deposits and host-units. The petrochemical study show that the Nopal Rhyolite and Escuadra Rhyolite are the source of U and of hydrothermal solutions [fr

  15. Air pollution dry deposition: radioisotopes as particles and volatiles

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This study focuses on determining volcanic ash and ambient airborne solids concentrations at various sampling sites subsequent to the Mt. St. Helens' eruption in order to develop an experimental basis for models predicting removal of airborne particles and gases by dry deposition onto outdoor surfaces. In addition, deposition rates were determined using dual tracer techniques in the field and in a wind tunnel in the laboratory

  16. Ash fusion temperatures and the transformations of coal ash particles to slag

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, S.; Wall, T.F.; Creelman, R.A.; Gupta, R. [Univ. of Newcastle, Callaghan (Australia)

    1996-12-31

    A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600{degrees}C. The temperatures corresponding to the rapid rate of shrinkage are shown to correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. The progressive changes in the range of chemical analysis (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenization, viscosity and ash fusion mechanisms.

  17. Ash fusion temperatures and the transformations of coal ash particles to slag

    Energy Technology Data Exchange (ETDEWEB)

    Wall, T.F.; Creelman, R.A.; Gupta, R.; Gupta, S. [Univ. of Newcastle (Australia)

    1996-10-01

    A mechanistic study is detailed in which coal ash is heated with the shrinkage and electrical resistance measured continuously up to a temperature of 1600{degrees}C. The temperatures corresponding to rapid rates of shrinkage are shown to correspond to the formation of eutectics identified on phase diagrams. Samples where therefore heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. The progressive changes in the range of chemical analysis (from SEM), the extent of undissolved ash particles and porosity are then quantified and related to the shrinkage events and standard ash fusion temperatures.

  18. Fly ash particles spheroidization using low temperature plasma energy

    OpenAIRE

    Shekhovtsov, V. V.; Volokitin, O. G.; Vitske, Rudolf Evaldovich; Kondratyuk, Alexey Alekseevich

    2016-01-01

    The paper presents the investigations on producing spherical particles 65-110 [mu]m in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition ...

  19. Project for solving of environmental problems caused by ash emission and deposition from the thermal power plant 'Nikola Tesla' at Obrenovac

    International Nuclear Information System (INIS)

    Simonovic, B.R.; Vukmirovic, Z.; Ilic, M.

    2002-01-01

    The problem of ash emission and deposition from the Thermal Power Plant 'Nikola Tesla' (TPPNT) in Obrenovac commences with the date of their construction. Up to now, mainly, some analysis of several possible influences of ash (emitted or deposited on the ash and slug dump) was done. We believe that is time now, due to the consequences for a long time, to pose and to resolve the whole problem of ash emission and deposition from TPPNT Obrenovac. Due to the very big production capacity, an enormous amount of fly ash (particle size of 90-200 μm) is emitted to a large area near Obrenovac. Very large quantities of ash and slug (more than 2 millions tons annually) produced during coal burning were deposited on the dump very close to the river Sava. Some of the multiple consequences due to elution of heavy metals, water spilling from the dump and mixing with ground water and surface water of river Sava, weathering of fine particles of ash by wind, acid rains near to the thermal power plants, and other influences of flying and deposited ash on the environment of the whole area are always present. Due to the complexity of the posed problem, a multidisciplinary experts' team was formed to cover all aspects of negative influences of ash emission and deposition from TPPNT Obrenovac. Our project comprises a large number of subprojects covering different problem solving, diminution or removal of all negative influences according to European standards and regulations. (author)

  20. Fly ash particles spheroidization using low temperature plasma energy

    Science.gov (United States)

    Shekhovtsov, V. V.; Volokitin, O. G.; Kondratyuk, A. A.; Vitske, R. E.

    2016-11-01

    The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO2; 20.61 wt.% Al2O3 and 17.55 wt.% Fe2O3 phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O2Si, phase, increase of O22Al20 and Fe2O3 phases and change in Al, O density of O22Al20 chemical unit cell.

  1. Deposition and Resuspension of Particles

    DEFF Research Database (Denmark)

    Lengweiler, P.; Nielsen, Peter V.; Moser, A.

    To investigate the physical process of deposition and resuspension of particles in the indoor environment, scale experiments are used and a sampling method is established. The influences of surface orientation and turbulence and velocity of the air on the dust load on a surface are analysed....

  2. Ash Deposit Formation and Deposit Properties. A Comprehensive Summary of Research Conducted at Sandia's Combustion Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Larry L. Baxter

    2000-08-01

    This report summarizes experimental and theoretical work performed at Sandia's Combustion Research Facility over the past eight years on the fate of inorganic material during coal combustion. This work has been done under four broad categories: coal characterization, fly ash formation, ash deposition, and deposit property development. The objective was to provide sufficient understanding of these four areas to be able to predict coal behavior in current and advanced conversion systems. This work has led to new characterization techniques for fuels that provide, for the first time, systematic and species specific information regarding the inorganic material. The transformations of inorganic material during combustion can be described in terms of the net effects of the transformations of these individual species. Deposit formation mechanisms provide a framework for predicting deposition rates for abroad range of particle sizes. Predictions based on these rates many times are quite accurate although there are important exceptions. A rigorous framework for evaluating deposit has been established. Substantial data have been obtained with which to exercise this framework, but this portion of the work is less mature than is any other. Accurate prediction of deposit properties as functions of fuel properties, boiler design, and boiler operating conditions represents the single most critical area where additional research is needed.

  3. Mechanism research on coupling effect between dew point corrosion and ash deposition

    International Nuclear Information System (INIS)

    Wang, Yun-Gang; Zhao, Qin-Xin; Zhang, Zhi-Xiang; Zhang, Zhi-Chao; Tao, Wen-Quan

    2013-01-01

    In order to study the coupling mechanism between ash deposition and dew point corrosion, five kinds of tube materials frequently used as anti-dew point corrosion materials were selected as research objects. Dew point corrosion and ash deposition experiments were performed with a new type experimental device in a Chinese thermal power plant. The microstructures of the materials and the composition of ash deposition were analyzed by X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS). The results showed that the ash deposition layer could be divided into non-condensation zone, the main condensation zone and the secondary condensation zone. The acid vapor condensed in the main condensation zone rather than directly on the tube wall surface. The dew point corrosion mainly is oxygen corrosion under the condition of the viscosity ash deposition, and the corrosion products are composed of the ash and acid reaction products in the outer layer, iron sulfate in the middle layer, and iron oxide in the inner layer. The innermost layer is the main corrosion layer. With the increase of the tube wall temperature, the ash deposition changes from the viscosity ash deposition to the dry loose ash deposition, the ash deposition rate decreases dramatically and dew point corrosion is alleviated efficiently. The sulfuric dew point corrosion resistance of the five test materials is as follows: 316L > ND > Corten>20G > 20 steel. -- Highlights: ► Dew point corrosion and ash deposition tests of five materials were performed. ► Acid vapor condensed in the ash deposit rather than directly on the tube surface. ► Dew point corrosion resistance is as follow: 316L > ND > Corten>20G > 20 steel. ► Dew point corrosion mainly is oxygen corrosion under viscosity ash deposition

  4. The Coupling Effect Research of Ash Deposition and Condensation in Low Temperature Flue Gas

    Directory of Open Access Journals (Sweden)

    Lei Ma

    2016-01-01

    Full Text Available Ash deposition is a key factor that deteriorates the heat transfer performance and leads to higher energy consumption of low pressure economizer working in low temperature flue gas. In order to study the ash deposition of heat exchange tubes in low temperature flue gas, two experiments are carried out with different types of heat exchange tubes in different flue gas environments. In this paper, Nusselt Number Nu and fouling factor ε are calculated to describe the heat transfer characteristics so as to study the ash deposition condition. The scanning electron microscope (SEM is used for the analysis of ash samples obtained from the outer wall of heat exchange tubes. The dynamic process of ash deposition is studied under different temperatures of outer wall. The results showed that ash deposition of heat exchanger will achieve a stable state in constant flue gas environment. According to the condition of condensation of acid vapor and water vapor, the process of ash deposition can be distinguished as mere ash deposition, acid-ash coupling deposition, and acid-water-ash coupling deposition.

  5. Separation of ultrafine particles from class F fly ashes

    Directory of Open Access Journals (Sweden)

    Acar Ilker

    2016-01-01

    Full Text Available In this study, ultrafine particles were recovered from Çatalağzı (CFA and Sugözü (SFA thermal power plant fly ashes using a specific hydraulic classification technology. Since fly ashes have a high tendency to be flocculated in water, settling experiments were first designed to determine the more effective dispersant and the optimum dosage. Two different types of the superplasticizers (SP polymers based on sulphonate (NSF, Disal and carboxylate (Glenium 7500 were used as the dispersing agents in these settling experiments. Hydraulic classification experiments were then conducted to separate ultrafine fractions from the fly ash samples on the basis of the settling experiments. According to the settling experiments, better results were achieved with the use of Disal for both CFA and SFA. The classification experiments showed that the overflow products with average particle sizes of 5.2 μm for CFA and 4.4 μm for SFA were separated from the respective as-received samples with acceptable yields and high enough recoveries of -5 μm (ultrafine particles. Overall results pointed out that the hydraulic classification technology used provided promising results in the ultrafine particle separations from the fly ash samples.

  6. Probe Measurements of Ash Deposit Formation Rate and Shedding in a Biomass Suspension-Fired boiler

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    The aim of this study was to investigate ash deposit formation rate, heat uptake reduction and deposit removal by using advanced online ash deposition and sootblowing probes in a 350 MWth suspension-fired boiler, utilizing wood and straw pellets as fuel. The influence of fuel type (straw share...

  7. The use of fly-ash particles for dating lake sediments

    Energy Technology Data Exchange (ETDEWEB)

    Rose, N L [Environmental Change Research Centre, University College London, London (United Kingdom)

    1998-08-01

    Fly-ash particles comprise two particle types, spheroidal carbonaceous particles (SCP) and inorganic ash spheres (IAS). In lake sediments, these particles form an unambiguous record of atmospheric deposition of industrial pollutants. The main temporal trends of these sediment records have been found to be remarkably consistent over wide geographical areas and these features can be used to ascribe dates to cores undated by other means. SCP are the main particle type used in this way as they are easier to extract and enumerate. IAS are morphologically similar to some natural particles (volcanic, meteoritic) and therefore show a natural background concentration at all pre-industrial sediment depths. Apart from this background temporal trends are similar to SCP and IAS could be used for dating in the same way. Gaining an indication of fuel-type change, either from IAS:SCP ratio or chemical characterization of SCP enables additional dates to be added to sediment cores through comparison with documentary evidence. In the future, as {sup 210}Pb becomes progressively unable to date the post-industrial sediment record, dating using fly-ash techniques may become increasingly important. (orig.) 17 refs.

  8. The use of fly-ash particles for dating lake sediments

    International Nuclear Information System (INIS)

    Rose, N.L.

    1998-01-01

    Fly-ash particles comprise two particle types, spheroidal carbonaceous particles (SCP) and inorganic ash spheres (IAS). In lake sediments, these particles form an unambiguous record of atmospheric deposition of industrial pollutants. The main temporal trends of these sediment records have been found to be remarkably consistent over wide geographical areas and these features can be used to ascribe dates to cores undated by other means. SCP are the main particle type used in this way as they are easier to extract and enumerate. IAS are morphologically similar to some natural particles (volcanic, meteoritic) and therefore show a natural background concentration at all pre-industrial sediment depths. Apart from this background temporal trends are similar to SCP and IAS could be used for dating in the same way. Gaining an indication of fuel-type change, either from IAS:SCP ratio or chemical characterization of SCP enables additional dates to be added to sediment cores through comparison with documentary evidence. In the future, as 210 Pb becomes progressively unable to date the post-industrial sediment record, dating using fly-ash techniques may become increasingly important. (orig.)

  9. Fouling deposition characteristic by variation of coal particle size and deposition temperature in DTF (Drop Tube Furnace)

    Energy Technology Data Exchange (ETDEWEB)

    Namkung, Hueon; Jeon, Youngshin; Kim, Hyungtaek [Ajou Univ., Suwon (Korea, Republic of). Div. of Energy Systems Research; Xu, Li-hua [IAE, Suwon (Korea, Republic of). Plant Engineering Center

    2013-07-01

    One of the major operation obstacles in gasification process is ash deposition phenomenon. In this investigation, experiment was carried out to examine coal fouling characteristics using a laminar DTF (Drop Tube Furnace) with variation of operating condition such as different coal size, and probe surface temperature. Four different samples of pulverized coal were injected into DTF under various conditions. The ash particles are deposited on probe by impacting and agglomerating action. Fouling grains are made of eutectic compound, which is made by reacting with acid minerals and alkali minerals, in EPMA (Electron Probe Micro-Analysis). And agglomeration area of fouling at top layer is wide more than it of middle and bottom layer. The major mineral factors of fouling phenomenon are Fe, Ca, and Mg. The deposition quantity of fouling increases with increasing particle size, high alkali mineral (Fe, Ca, and Mg) contents, and ash deposition temperature.

  10. FALL3D: A Computational Model for Trans-port and Deposition of Volcanic Ash

    OpenAIRE

    Folch, A.; Costa, A.; Macedonio, G.

    2008-01-01

    FALL3D is a 3-D time-dependent Eulerian model for the transport and deposition of 8 volcanic ash. The model solves the advection-diffusion-sedimentation (ADS) equa- 9 tion on a structured terrain-following grid using a second-order Finite Differences 10 (FD) explicit scheme. Different parameterizations for the eddy diffusivity tensor 11 and for the particle terminal settling velocities can be used. The code, written 12 in FORTRAN 90, is available in both serial and parallel ver...

  11. Ash transformation and deposition behavior during co-firing biomass with sewage sludge

    DEFF Research Database (Denmark)

    Wang, Liang; Wu, Hao; Jensen, Peter Arendt

    combustion wheat straw, fine fly ash particles smaller than 2.5 μm are mainly formed due to vaporization, nucleation and condensation of K, Cl, S and P species. Large fly ash particles consist of condensed potassium chloride crystals and molten/partial molten spherical particles rich in Ksilicates and K...

  12. Impact of coal fly ash addition on ash transformation and deposition in a full-scale wood suspension-firing boiler

    DEFF Research Database (Denmark)

    Wu, Hao; Bashir, Muhammad Shafique; Jensen, Peter Arendt

    2013-01-01

    Ash transformation and deposition during pulverized wood combustion in a full-scale power plant boiler of 800 MWth were studied with and without the addition of coal fly ash. The transient ash deposition behavior was characterized by using an advanced deposit probe system at two boiler locations...... constant after a few hours. The formed deposits, especially those at the location with low flue gas temperatures, contained a considerable amount of K2SO4, KCl, and KOH/K2CO3. With the addition of a large amount (about 4 times of the mass flow of wood ash) of coal fly ash to the boiler, these alkali...

  13. Dry deposition of particles to ocean surfaces

    NARCIS (Netherlands)

    Larsen, S.E.; Edson, J.B.; Hummelshoj, P.; Jensen, N.O.; Leeuw, G. de; Mestayer, P.G.

    1995-01-01

    Dry deposition of atmospheric particles mainly depends on wind speed and particle diameter. The dry deposition velocity, Vd, is found to vary by a factor of 100-1,000 with diameter in a likely diameter range, adding uncertainty to deposition estimates, because the diameter distribution for many

  14. Study of the composition and gas-phase release characteristics of salt material extracted from MSW ash particles using STA

    DEFF Research Database (Denmark)

    Arvelakis, Stelios; Frandsen, Flemming; Koukios, E.G.

    2007-01-01

    material extracted from MSW ash particles using a six-stage leaching process is studied using simultaneous thermal analysis (STA). The produced results provide useful information regarding the composition of the salt material and its melting behavior that is considered to play an important role...... to deposition and corrosion problems at MSW incinerators. The results may be used to model the deposition process and to the better understanding of the corrosion process during MSW incineration....

  15. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    Directory of Open Access Journals (Sweden)

    H. F. Dacre

    2013-02-01

    Full Text Available The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4–18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h, a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes, it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small particles (< 30 μm diameter. NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of < 10 μm diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.

  16. Ice nucleation properties of fine ash particles from the Eyjafjallajökull eruption in April 2010

    Directory of Open Access Journals (Sweden)

    I. Steinke

    2011-12-01

    Full Text Available During the eruption of the Eyjafjallajökull volcano in the south of Iceland in April/May 2010, about 40 Tg of ash mass were emitted into the atmosphere. It was unclear whether volcanic ash particles with d < 10 μm facilitate the glaciation of clouds. Thus, ice nucleation properties of volcanic ash particles were investigated in AIDA (Aerosol Interaction and Dynamics in the Atmosphere cloud chamber experiments simulating atmospherically relevant conditions. The ash sample that was used for our experiments had been collected at a distance of 58 km from the Eyjafjallajökull during the eruption period in April 2010. The temperature range covered by our ice nucleation experiments extended from 219 to 264 K, and both ice nucleation via immersion freezing and deposition nucleation could be observed. Immersion freezing was first observed at 252 K, whereas the deposition nucleation onset lay at 242 K and RHice =126%. About 0.1% of the volcanic ash particles were active as immersion freezing nuclei at a temperature of 249 K. For deposition nucleation, an ice fraction of 0.1% was observed at around 233 K and RHice =116%. Taking ice-active surface site densities as a measure for the ice nucleation efficiency, volcanic ash particles are similarly efficient ice nuclei in immersion freezing mode (ns,imm ~ 109 m−2 at 247 K compared to certain mineral dusts. For deposition nucleation, the observed ice-active surface site densities ns,dep were found to be 1011 m−2 at 224 K and RHice =116%. Thus, volcanic ash particles initiate deposition nucleation more efficiently than Asian and Saharan dust but appear to be poorer ice nuclei than ATD particles. Based on the experimental data, we have derived ice-active surface site densities as a function of temperature for immersion freezing and of relative humidity over ice and temperature for

  17. Ash particle erosion on steam boiler convective section

    Energy Technology Data Exchange (ETDEWEB)

    Meuronen, V

    1998-12-31

    In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. A new, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosion wear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling and circulating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can be used to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an in- line tube bank with six tube rows, and a staggered tube bark with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss

  18. A scanning electron microscopy study of ash, char, deposits and fuels from straw combustion and co-combustion of coal and straw

    Energy Technology Data Exchange (ETDEWEB)

    Sund Soerensen, H.

    1998-07-01

    The SEM-study of samples from straw combustion and co-combustion of straw and coal have yielded a reference selection of representative images that will be useful for future comparison. The sample material encompassed potential fuels (wheat straw and grain), bottom ash, fly ash and deposits from straw combustion as well as fuels (coal and wheat straw), chars, bottom ash, fly ash and deposits from straw + coal co-combustion. Additionally, a variety of laboratory ashes were studied. SEM and CCSEM analysis of the samples have given a broad view of the inorganic components of straw and of the distribution of elements between individual ash particles and deposits. The CCSEM technique does, however, not detect dispersed inorganic elements in biomass, so to get a more complete visualization of the distribution of inorganic elements additional analyses must be performed, for example progressive leaching. In contrast, the CCSEM technique is efficient in characterizing the distribution of elements in ash particles and between ash fractions and deposits. The data for bottom ashes and fly ashes have indicated that binding of potassium to silicates occurs to a significant extent. The silicates can either be in the form of alumino-silicates or quartz (in co-combustion) or be present as straw-derived amorphous silica (in straw combustion). This process is important for two reasons. One is that potasium lowers the melting point of silica in the fly ash, potentially leading to troublesome deposits by particle impaction and sticking to heat transfer surfaces. The other is that the reaction between potassium and silica in the bottom ash binds part of the potassium meaning that it is not available for reaction with chlorine or sulphur to form KCl or K{sub 2}SO{sub 4}. Both phases are potentially troublesome because they can condense of surfaces to form a sticky layer onto which fly ash particles can adhere and by inducing corrosion beneath the deposit. It appears that in the studied

  19. Deposition and Resuspension of Particles

    DEFF Research Database (Denmark)

    Lengweiler, P.; Nielsen, Peter V.; Moser, A.

    A new experimental set-up to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airBorne dust concentration considerably. As a basis for developing methods to eliminate dust related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension....

  20. Experimental measurements of the thermal conductivity of ash deposits: Part 2. Effects of sintering and deposit microstructure

    Energy Technology Data Exchange (ETDEWEB)

    A. L. Robinson; S. G. Buckley; N. Yang; L. L. Baxter

    2000-04-01

    The authors report results from an experimental study that examines the influence of sintering and microstructure on ash deposit thermal conductivity. The measurements are made using a technique developed to make in situ, time-resolved measurements of the effective thermal conductivity of ash deposits formed under conditions that closely replicate those found in the convective pass of a commercial boiler. The technique is designed to minimize the disturbance of the natural deposit microstructure. The initial stages of sintering and densification are accompanied by an increase in deposit thermal conductivity. Subsequent sintering continues to densify the deposit, but has little effect on deposit thermal conductivity. SEM analyses indicates that sintering creates a layered deposit structure with a relatively unsintered innermost layer. They hypothesize that this unsintered layer largely determines the overall deposit thermal conductivity. A theoretical model that treats a deposit as a two-layered material predicts the observed trends in thermal conductivity.

  1. Immersion freezing induced by different kinds of coal fly ash: Comparing particle generation methods and measurement techniques

    Science.gov (United States)

    Grawe, Sarah; Augustin-Bauditz, Stefanie; Clemen, Hans-Christian; Eriksen-Hammer, Stine; Lubitz, Jasmin; Schneider, Johannes; Stratmann, Frank; Wex, Heike

    2017-04-01

    To date, a lot of effort has been put into the identification and characterization of atmospheric ice nucleating particles (INPs), which may influence both weather and climate. The majority of studies focuses on INPs from natural origin such as biological particles or mineral dust particles (Hoose and Möhler 2012, Murray et al. 2012). Combustion ashes, being possible sources of anthropogenic INPs, have rarely been investigated in the past. Ash particles may be emitted into the atmosphere either by the action of wind from ash deposits on the ground (bottom ash), or during the combustion process (fly ash). Two recent studies (Umo et al., 2015; Grawe et al., 2016) identified fly ash from coal combustion as the most efficient of the investigated samples (including also bottom ashes from wood and coal combustion). These results motivate the here presented study in which we investigated the immersion freezing behavior of four coal fly ash samples taken from the filters of different coal-fired power plants in Germany. A combination of two instruments was used to capture the temperature range from 0 °C to the homogeneous freezing limit at around -38 °C. Firstly, the new Leipzig Ice Nucleation Array (LINA) was used, where droplets from an ash-water suspension are pipetted onto a cooled plate. Secondly, we used the Leipzig Aerosol Cloud Interaction Simulator (LACIS; Hartmann et al., 2011), a laminar flow tube in which every droplet contains a single size-segregated ash particle. Here, it was possible to study the effect of different kinds of particle generation, i.e., atomization of an ash-water suspension, and aerosolization of dry ash material. The composition of the ash particles was investigated by means of single particle aerosol mass spectrometry and particles were sampled on filters for environmental scanning electron microscope analysis. Our measurements show that all four fly ash samples feature a similar immersion freezing behavior (ice fractions vary by a

  2. Multiphase flow modelling of volcanic ash particle settling in water using adaptive unstructured meshes

    Science.gov (United States)

    Jacobs, C. T.; Collins, G. S.; Piggott, M. D.; Kramer, S. C.; Wilson, C. R. G.

    2013-02-01

    Small-scale experiments of volcanic ash particle settling in water have demonstrated that ash particles can either settle slowly and individually, or rapidly and collectively as a gravitationally unstable ash-laden plume. This has important implications for the emplacement of tephra deposits on the seabed. Numerical modelling has the potential to extend the results of laboratory experiments to larger scales and explore the conditions under which plumes may form and persist, but many existing models are computationally restricted by the fixed mesh approaches that they employ. In contrast, this paper presents a new multiphase flow model that uses an adaptive unstructured mesh approach. As a simulation progresses, the mesh is optimized to focus numerical resolution in areas important to the dynamics and decrease it where it is not needed, thereby potentially reducing computational requirements. Model verification is performed using the method of manufactured solutions, which shows the correct solution convergence rates. Model validation and application considers 2-D simulations of plume formation in a water tank which replicate published laboratory experiments. The numerically predicted settling velocities for both individual particles and plumes, as well as instability behaviour, agree well with experimental data and observations. Plume settling is clearly hindered by the presence of a salinity gradient, and its influence must therefore be taken into account when considering particles in bodies of saline water. Furthermore, individual particles settle in the laminar flow regime while plume settling is shown (by plume Reynolds numbers greater than unity) to be in the turbulent flow regime, which has a significant impact on entrainment and settling rates. Mesh adaptivity maintains solution accuracy while providing a substantial reduction in computational requirements when compared to the same simulation performed using a fixed mesh, highlighting the benefits of an

  3. Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction

    Science.gov (United States)

    Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas

    2016-04-01

    Airborne particles from explosive volcanic eruptions are a major safety threat for aviation operations. The fine fraction of the emitted particles (fan blades and rotor-path components, and can also cause contamination or blockage of electrical systems and the fuel system such as fuel nozzles and air bleed filters. Ash particles that enter the hot-section of the engine (combustor and turbine stages; temperature between 1400-1800°C) are rapidly heated above the glass transition temperature (about 650-1000°C) and become soft (or form a melt) and can stick as re-solidified deposits on nozzle guide vanes. The glass deposits change the internal aerodynamic airflow in the engine and can affect the cooling capability of the different components by clogging the cooling inlets/outlets, which can lead to a loss of power or flame-out. The nature of volcanic ash ingestion is primarily influenced by the fan at the front of the engine which produces the thrust that drives the aircraft. The ingested air is split between the core (compressor/combustor/turbine) and bypass (thrust) at a ratio of typically between, 1:5-10 on modern engines. Consequently, the ash particles are fractionated between the core and bypass by the geometry and dynamics of the fan blades. This study uses computational fluid dynamics (CFD) simulations of particle-laden airflows into a turbofan engine under different atmospheric and engine operation conditions. The main aim was to investigate the possible centrifugal effect of the fan blades as a function of particle size, and to relate this to the core intake concentration. We generated a generic 3D axial high-bypass turbofan engine using realistic dimensions of the turbofan, engine intake and other aerodynamically relevant parts. The CFD experiments include three scenarios of aircraft performance (climb, cruise and descent) and for two different typical altitude ranges (10000 and 39000 ft). The fluid dynamics simulations were carried out using a commercial

  4. Effects of ashes in solid fuels on fuel particle charging during combustion in an air stream

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A.G.; Fialkov, B.S.; Mel' nichuk, A.Yu.; Khvan, L.A.

    1982-09-01

    Black coal from the Karaganda basin is mixed with sodium chloride and graphite. Coal characteristics are given in a table (density, ashes, content of silica, aluminium oxides, iron oxides, calcium oxides, potassium oxides and magnesium oxides). Effects of ash fluctuations on electric potential of fuel particles during combustion are analyzed. Analyses show that with increasing ash content electric potential of fuel particles decreases and reaches the minimum when ash content ranges from 70 to 80 %. Particles with electric potential are generated during chemical processes between carbon and oxygen when coal is burned in an air stream. (5 refs.) (In Russian)

  5. Fundamental study of ash formation and deposition: Effect of reducing stoichiometry

    Energy Technology Data Exchange (ETDEWEB)

    Helble, J.J.; Bool, L.E.; Kang, S.G. [and others

    1995-11-01

    This project is designed to examine the effects of combustion stoichiometry on the fundamental aspects of ash formation and ash deposit initiation. Emphasis is being placed on reducing stoichiometries associated with low-NOx combustion, although a range of oxidant/fuel ratios are being considered. Previous work has demonstrated that ash formation depends strongly upon coal mineralogy, including mineral type, size, amount, and the presence of organically associated inorganic species. Combustion temperature and the oxidation state of iron also play a significant role. As these latter items will vary with changes in stoichiometry, research to determine the net effect on deposition is required.

  6. The relation between pre-eruptive bubble size distribution, ash particle morphology, and their internal density: Implications to volcanic ash transport and dispersion models

    Science.gov (United States)

    Proussevitch, Alexander

    2014-05-01

    Parameterization of volcanic ash transport and dispersion (VATD) models strongly depends on particle morphology and their internal properties. Shape of ash particles affects terminal fall velocities (TFV) and, mostly, dispersion. Internal density combined with particle size has a very strong impact on TFV and ultimately on the rate of ash cloud thinning and particle sedimentation on the ground. Unlike other parameters, internal particle density cannot be measured directly because of the micron scale sizes of fine ash particles, but we demonstrate that it varies greatly depending on the particle size. Small simple type ash particles (fragments of bubble walls, 5-20 micron size) do not contain whole large magmatic bubbles inside and their internal density is almost the same as that of volcanic glass matrix. On the other side, the larger compound type ash particles (>40 microns for silicic fine ashes) always contain some bubbles or the whole spectra of bubble size distribution (BSD), i.e. bubbles of all sizes, bringing their internal density down as compared to simple ash. So, density of the larger ash particles is a function of the void fraction inside them (magmatic bubbles) which, in turn, is controlled by BSD. Volcanic ash is a product of the fragmentation of magmatic foam formed by pre-eruptive bubble population and characterized by BSD. The latter can now be measured from bubble imprints on ash particle surfaces using stereo-scanning electron microscopy (SSEM) and BubbleMaker software developed at UNH, or using traditional high-resolution X-Ray tomography. In this work we present the mathematical and statistical formulation for this problem connecting internal ash density with particle size and BSD, and demonstrate how the TFV of the ash population is affected by variation of particle density.

  7. Reconnaissance map showing thickness of volcanic ash deposits in the greater Hilo area, Hawaii

    Science.gov (United States)

    Buchanan-Banks, Jane M.

    1983-01-01

    This study was undertaken to determine the thickness and distribution of volcanic ash deposits in the greater Hilo area, Hawaii, as a step toward evaluating their susceptibility to failure during earthquake shaking. On several occasions their instability has resulted in serious damage. For example, the 1868 earthquake (m=7+), following a prolonged rainy period, caused a debris flow of hillside ash deposits that killed 31 people in Wood Valley (Bringham, 1869). The 1973 Honomu earthquake (m=6.2) resulted in more damage from shaking to areas underlain by ash deposits in the older part of Hilo than in other areas, and soil slips in ash, as well as rockfalls, were common along the roads north of town (Nielsen and others, 1977). 

  8. Deposition of aerosol particles in bent pipe

    International Nuclear Information System (INIS)

    Matsui, Hiroshi; Ohhata, Tsutomu

    1989-01-01

    An equation to estimate deposition fraction of aerosol particles in a bent pipe is derived and the validity is verified experimentally. The equation is obtained by assuming that the resultant acceleration of the gravity and the centrifugal force induced in the bend acts on the aerosol particles, and is found to give a relatively accurate estimation of the deposition fraction if a certain correction factor is introduced to the equation. The deposition fraction has a minimum against Reynold number, and the deposition due to centrifugal force dominates at greater Reynolds number than that at the minimum deposition fraction. On the other hand, the smaller the radius of curvature of the bend is, the larger the deposition fraction due to the centrifugal force is. (author)

  9. Particle Tracking and Deposition from CFD Simulations using a Viscoelastic Particle Model

    NARCIS (Netherlands)

    Losurdo, M.

    2009-01-01

    In the present dissertation the mathematical modelling of particle deposition is studied and the solution algorithms for particle tracking, deposition and deposit growth are developed. Particle deposition is modelled according to mechanical impact and contact mechanics taking into account the

  10. Coal Ash Aerosol in East Asian Outflow as a Source for Oceanic Deposition of Iron and Other Metals

    Science.gov (United States)

    Anderson, J. R.; Hua, X.

    2008-12-01

    While ocean deposition of East Asian dust is given significant emphasis as a source of biologically-active trace elements, iron in particular, dust events are episodic and highly seasonal. There is, however, a constant source of aerosol that is chemically similar to dust (albeit amorphous in structure rather than crystalline) in the ash particles emitted from many hundreds of coal-fired power plants that are sited along the entire coastal region of China and Korea. The emission controls on these facilities vary widely and, in even cases of state-of-the-art emission controls, the secondary release of ash can be significant. There are of course even more small industrial and household sources of coal combustion emissions, in most cases with little or no emissions controls. Ash from a modern coal-fired power facility in Korea has been examined chemically and morphologically with electron microscopic techniques. As is characteristic of all such facilities, two principal types of ash are present: (1) flyash, silicate glass spheres that are emitted with the smoke and removed by electrostatic precipitators; and (2) bottom ash, "clinkers" and noncombustible material sticking to the furnace walls that are mixed with water and ground after cooling, then removed as a slurry to a dumping area. In addition, iron sulfide (pyrite) is a common constituent of coal and provides both a source of sulfur dioxide gas and also molten iron spherical particles in the ash. The iron spheres then are rapidly oxidized upon cooling. Bottom ash is a more complex material than flyash in that it contains more iron and other trace metals, plus it contains varying amounts of uncombusted carbon. The post-combustion handling of bottom ash can lead to significant emissions despite the fact that little or none goes out the stack. The iron oxide spheres can also be emitted by this secondary method. The concentrations of ash can be very high in close proximity to power plants (PM10 of several hundred

  11. Quantification of Ash Deposit Build-up and Removal in a Straw and Wood Suspension-Fired Boiler

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    2011-01-01

    The aim of this study was to investigate ash deposit formation rate, heat uptake reduction and deposit removal by using advanced online ash deposition and sootblowing probes in a 350 MWth suspension­fired boiler, utilizing wood and straw pellets as fuel. The influence of fuel type (straw share...

  12. Fractionation of elements by particle size of ashes ejected from Copahue Volcano, Argentina.

    Science.gov (United States)

    Gómez, Dario; Smichowski, Patricia; Polla, Griselda; Ledesma, Ariel; Resnizky, Sara; Rosa, Susana

    2002-12-01

    The volcano Copahue, Neuquén province, Argentina has shown infrequent explosive eruptions since the 18th century. Recently, eruptive activity and seismicity were registered in the period July-October, 2000. As a consequence, ash clouds were dispersed by winds and affected Caviahue village located at about 9 km east of the volcano. Samples of deposited particles from this area were collected during this episode for their chemical analysis to determine elements of concern with respect to the health of the local population and its environment. Different techniques were used to evaluate the distribution of elements in four particle size ranges from 36 to 300 microm. X-ray powder diffraction (XRD) was selected to detect major components namely, minerals, silicate glass, fragments of rocks and sulfurs. Major and minor elements (Al, Ca, Cl, Fe, K, Mg, Mn, Na, S, Si and Ti), were detected by energy dispersive X ray analysis (EDAX). Trace element (As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, U, V and Zn) content was quantified by inductively coupled plasma-mass spectrometry (ICP-MS). Nuclear activation analysis (NAA) was employed for the determination of Ce, Co, Cs, Eu, Hf, La, Lu, Rb, Sc, Sm, Ta and Yb. An enrichment was observed in the smallest size fraction of volcanic ashes for four elements (As, Cd, Cu and Sb) of particular interest from the environmental and human health point of view.

  13. Occurrence of volcanic ash in the Quaternary alluvial deposits, lower ...

    Indian Academy of Sciences (India)

    of finely laminated silty sand and gravel lenses. ... undulating upper contact following the pre-existing ... The ash material is light with its specific .... negative Eu-anomaly, area enclosed within blue line indicates compositional range of the distal ...

  14. Orientation specific deposition of mesoporous particles

    Directory of Open Access Journals (Sweden)

    Tomas Kjellman

    2014-11-01

    Full Text Available We present a protocol for a facile orientation specific deposition of plate-like mesoporous SBA-15 silica particles onto a surface (mesopores oriented normal to surface. A drop of an aqueous dispersion of particles is placed on the surface and water vaporizes under controlled relative humidity. Three requirements are essential for uniform coverage: particle dispersion should not contain aggregates, a weak attraction between particles and surface is needed, and evaporation rate should be low. Aggregates are removed by stirring/sonication. Weak attraction is realized by introducing cationic groups to the surface. Insight into the mechanisms of the so-called coffee stain effect is also provided.

  15. Ash transformation and deposit build-up during biomass suspension and grate firing: Full-scale experimental studies

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    2012-01-01

    An attractive option for reducing the net CO2 emissions is to substitute coal with biomass in large power plant boilers. However, the presence of chlorine (Cl) and alkali metals (K, Na) in biomassmay induce large operational problems due to ash deposit formation on the superheater tubes. The aim...... of this study was to investigate ash transformation and deposition behavior in two biomass-fired boilers, firing wheat straw and/or wood. The influence of strawfiring technology (grate and suspension) on the ash transformation, deposit formation rate and deposit characteristics has been investigated. Bulk...... elemental analysis of fly ashes revealed that fly ash from suspension firing of straw has high contents of Si, K and Ca, while fly ash from straw firing on grate was rich in the volatile elements K, Cl and S. Investigations of deposit formation ratesweremade in the superheater and convective pass regions...

  16. Investigation of the possibility of binding fly ash particles by elemental sulphur

    Directory of Open Access Journals (Sweden)

    Vidojković V.

    2006-01-01

    Full Text Available Thermal power plants in Serbia use lignite for electrical power production The secondary product of coal combustion is fly ash in the amount of 17%. Fly ash causes the pollution of air, water and soil, and also cause many human, especially lung diseases. Secondary sulphur is a product of crude oil refining. The aim of this study was to investigate the use of sulphur as a bonding material in ultra fine particle agglomeration (smaller than 63 μm in fly ash. The agglomeration should make the ash particles larger and heavy enough to fall without flying fractions. The experiments showed that during the homogenization of the ashes and sulphur from 150 to 170 °C in a reactor with intensive mixing, an amount of 15% sulphur was sufficient to bond particles and cause agglomeration without visible flying fractions.

  17. Full-scale ash deposition measurements at Avedøre Power Plant unit 2 during suspension-firing of wood with and without coal ash addition

    DEFF Research Database (Denmark)

    Wu, Hao; Shafique Bashir, Muhammad; Jensen, Peter Arendt

    The formation of deposits during suspension-firing of wood at Avedøre Power Plant unit 2 (AVV2) was studied by using an advanced deposit probe system. The tests were conducted both with and without coal ash addition, and at two different locations with flue gas temperatures of 1250-1300 oC and 750...... with a high flue gas temperature of 1250-1300 oC, although the addition of coal fly ash increased the differential deposit formation rate (DDF-rate) and the ash deposition propensity, the deposit removal frequency were considerably increased and the major shedding mechanism was changed from soot...... corrosion. At the location with a low flue gas temperature of 750-800 oC, the addition of coal fly ash reduced the ash deposition propensity and caused the formed deposits being easily removable. Moreover, the KCl and KOH/K2CO3 found in the low-temperature deposits without coal ash addition disappeared when...

  18. Empirical prediction of ash deposition propensities in coal-fired utilities

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, F.

    1997-01-01

    This report contain an outline of some of the ash chemistry indices utilized in the EPREDEPO (Empirical PREdiction of DEPOsition) PC-program, version 1.0 (DEPO10), developed by Flemming Frandsen, The CHEC Research Programme, at the Department of Chemical Engineering, Technical University of Denmark. DEPO10 is a 1st generation FTN77 Fortran PC-programme designed to empirically predict ash deposition propensities in coal-fired utility boilers. Expectational data (empirical basis) from an EPRI-sponsored survey of ash deposition experiences at coal-fired utility boilers, performed by Battelle, have been tested for use on Danish coal chemistry - boiler operational conditions, in this study. (au) 31 refs.

  19. Usability value and heavy metals accumulation in forage grasses grown on power station ash deposit

    Directory of Open Access Journals (Sweden)

    Simić Aleksandar S.

    2015-01-01

    Full Text Available The study of five forage grasses (Lolium multiflorum, Festuca rubra, Festuca arundinacea, Arrhenatherum elatius and Dactylis glomerata was conducted on an uncontaminated cultivated land, of leached chernozem type, and on “Nikola Tesla A” (TENT A thermal power station ash deposit. The concentrations of: As, Pb, Cd, Zn, Ni, Fe i Cu in grasses grown on two media were compared. Grass samples have been collected in tillering stage, when they were in full development. During the vegetative period three replications cut was conducted at about 3-5 cm height, imitating mowing and grazing. The concentrations of As and Ni were elevated in media samples collected from TENT A ash deposit, while the level of all studied elements in soil samples collected from cultivated land were within allowed limits. The variance of certain elements amounts in plant material collected from TENT A ash deposit was less homogeneous; the concentrations of As, Fe and Ni were higher in grasses collected from ash deposit, but Pb and Cu concentrations were higher in grasses grown on cultivated land. The concentrations of Zn were approximately the same in plants collected from the sites, whereas Cd concentrations were slightly increased in grasses grown on ash deposit. In general, it can be concluded from the results of this study that the concentrations of heavy metals in plants collected from both sites do not exceed maximal tolerant levels for fodder. The use of grasses grown on ash deposit for forage production should be taken with reserve. [Projekat Ministarstva nauke Republike Srbije, br. TR 31016: Unapređenje tehnologije gajenja krmnih biljaka na oranicama i travnjacima

  20. Methodical studies of groundwater pollution caused by fly ash deposits from coal-fired power plants

    International Nuclear Information System (INIS)

    Spuziak-Salzenberg, D.

    1990-01-01

    The risk potential of fly ash deposits from fossil-fuel power plants was investigated through laboratory elution experiments (single elution, multiple elution, column leaching). The groundwater risk potential in the case of indiscriminate, unsealed dumping is high because of an increased water hardness and due to sulfate, molybdenum, selenium, boron, chromium, barium, strontium and arsenic contamination. Higher barium and strontium concentrations are typical of fly ash deposits. Barium and strontium thus serve as target elements for identification of sites of long-standing pollution. The risks of arsenic leaching are discussed in detail. (orig./LU) [de

  1. Mineralogical investigations into ash deposits of selected brown coals; Mineralogische Untersuchungen an Ascheansaetzen ausgewaehlter Braunkohlen

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, J.; Ullrich, B. [Technische Univ. Dresden, Inst. fuer Geotechnik (Germany)

    2003-07-01

    Within the framework of the research project financed by the Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AIF) ''Experimental investigations into the formation of ash deposits from stack gases during the combustion of pulverised lignite'' and supervised by the chair of power station technology (Institute of Energy Technology) of the Dresden Technical University, the mineral composition of ash deposits of six different coals were investigated: two coal blends (different countries worldwide), two lignites from east from the River Elbe (types WM and JAe), one from west of the River Elbe and one Rhenish lignite. (orig.)

  2. MAFALDA: An early warning modeling tool to forecast volcanic ash dispersal and deposition

    Science.gov (United States)

    Barsotti, S.; Nannipieri, L.; Neri, A.

    2008-12-01

    Forecasting the dispersal of ash from explosive volcanoes is a scientific challenge to modern volcanology. It also represents a fundamental step in mitigating the potential impact of volcanic ash on urban areas and transport routes near explosive volcanoes. To this end we developed a Web-based early warning modeling tool named MAFALDA (Modeling and Forecasting Ash Loading and Dispersal in the Atmosphere) able to quantitatively forecast ash concentrations in the air and on the ground. The main features of MAFALDA are the usage of (1) a dispersal model, named VOL-CALPUFF, that couples the column ascent phase with the ash cloud transport and (2) high-resolution weather forecasting data, the capability to run and merge multiple scenarios, and the Web-based structure of the procedure that makes it suitable as an early warning tool. MAFALDA produces plots for a detailed analysis of ash cloud dynamics and ground deposition, as well as synthetic 2-D maps of areas potentially affected by dangerous concentrations of ash. A first application of MAFALDA to the long-lasting weak plumes produced at Mt. Etna (Italy) is presented. A similar tool can be useful to civil protection authorities and volcanic observatories in reducing the impact of the eruptive events. MAFALDA can be accessed at http://mafalda.pi.ingv.it.

  3. Deposition kinetics of nanocolloidal gold particles

    NARCIS (Netherlands)

    Brouwer, E.A.M.; Kooij, Ernst S.; Hakbijl, Mark; Wormeester, Herbert; Poelsema, Bene

    2005-01-01

    The deposition kinetics of the irreversible adsorption of citrate-stabilized, nanocolloidal gold particles on Si/SiO2 surfaces, derivatized with (aminopropyl)triethoxysilane (APTES), is investigated in situ using single wavelength optical reflectometry. A well-defined flow of colloids towards the

  4. Deposit formation in a full-scale pulverized wood-fired power plant with and without coal fly ash addition

    DEFF Research Database (Denmark)

    Wu, Hao; Shafique Bashir, Muhammad; Jensen, Peter Arendt

    2013-01-01

    Ash transformation and deposition in a pulverized wood-fired power plant boiler of 800 MWth were studied with and without the addition of coal fly ash. The transient ash deposition behavior was investigated by using an advanced deposit probe system at two different boiler locations with flue gas...... at the low-temperature location showed a slow initial build-up and a stable mass of deposits after approximately 1-5 h. The deposits collected during pulverized wood combustion contained a considerable amount of K2SO4, KCl, and KOH/K2CO3. With the addition of coal fly ash (~4 times of the mass flow of wood...... ash) to the boiler, these alkali species were effectively removed both in the fly ash and in the deposits, and a more frequent shedding of the deposits was observed. The results imply that coal fly ash can be an effective additive to reduce ash deposition and corrosion problems in a pulverized wood...

  5. Evaluation of ash deposits during experimental investigation of co-firing of Bosnian coal with wooden biomass

    Energy Technology Data Exchange (ETDEWEB)

    Smajevic, Izet; Kazagic, Anes [JP Elektroprivreda BiH d.d., Sarajevo (Bosnia and Herzegovina); Sarajevo Univ. (Bosnia and Herzegovina). Faculty of Mechanical Engineering

    2008-07-01

    The paper is addressed to the development and use different criteria for evaluation of ash deposits collected during experimental co-firing of Bosnian coals with wooden biomass. Spruce saw dust was used for the co-firing tests with the Kakanj brown coal and with a lignite blend consisted of the Dubrave lignite and the Sikulje lignite. The coal/biomass mixtures at 93:7 %w and at 80:20 %w were tested. Experimental lab-scale facility PF entrained flow reactor is used for the co-firing tests. The reactor allows examination of fouling/slagging behaviors and emissions at various and infinitely variable process temperature which can be set at will in the range from ambient to 1560 C. Ash deposits are collected on two non-cooled ceramic probes and one water-cooled metal surface. Six different criteria are developed and used to evaluate behavior of the ash deposits on the probes: ash deposit shape, state and structure, which are analyzed visually - photographically and optically by a microscope, rate of adhesion and ash deposit strength, analyzed by physic acting to the ash deposits, and finally deposition rate, determined as a mass of the deposit divided by the collecting area and the time of collecting. Furthermore, chemical composition analysis and AFT of the ash deposits were also done to provide additional information on the deposits. (orig.)

  6. Biomimetic thermal barrier coating in jet engine to resist volcanic ash deposition

    Science.gov (United States)

    Song, Wenjia; Major, Zsuzsanna; Schulz, Uwe; Muth, Tobias; Lavallée, Yan; Hess, Kai-Uwe; Dingwell, Donald B.

    2017-04-01

    The threat of volcanic ash to aviation safety is attracting extensive attention when several commercial jet aircraft were damaged after flying through volcanic ash clouds from the May 1980 eruptions of Mount St. Helen in Washington, U.S. and especially after the air traffic disruption in 2010 Eyjafjallajökull eruption. A major hazard presented by volcanic ash to aircraft is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Due to the fact ash has a lower melting point, around 1100 °C, than the gas temperature in the hot section (between 1400 to 2000 °C), this cause the ash to melt and potentially stick to the internal components (e.g., combustor and turbine blades), this cause the ash to melt and potentially stick to the internal components of the engine creating, substantial damage or even engine failure after ingestion. Here, inspiring form the natural surface of lotus leaf (exhibiting extreme water repellency, known as 'lotus effect'), we firstly create the multifunctional surface thermal barrier coatings (TBCs) by producing a hierarchical structure with femtosecond laser pulses. In detail, we investigate the effect of one of primary femtosecond laser irradiation process parameter (scanning speed) on the hydrophobicity of water droplets onto the two kinds of TBCs fabricated by electron-beam physical vapor deposition (EB-PVD) and air plasma spray (APS), respectively as well as their corresponding to morphology. It is found that, comparison with the original surface (without femtosecond laser ablation), all of the irradiated samples demonstrate more significant hydrophobic properties due to nanostructuring. On the basis of these preliminary room-temperature results, the wettability of volcanic ash droplets will be analysed at the high temperature to constrain the potential impact of volcanic ash on the jet engines.

  7. Kinetics of particle deposition at heterogeneous surfaces

    Science.gov (United States)

    Stojiljković, D. Lj.; Vrhovac, S. B.

    2017-12-01

    The random sequential adsorption (RSA) approach is used to analyze adsorption of spherical particles of fixed diameter d0 on nonuniform surfaces covered by square cells arranged in a square lattice pattern. To characterize such pattern two dimensionless parameters are used: the cell size α and the cell-cell separation β, measured in terms of the particle diameter d0. Adsorption is assumed to occur if the particle (projected) center lies within a cell area. We focus on the kinetics of deposition process in the case when no more than a single disk can be placed onto any square cell (α deposition process is not consistent with the power law behavior. However, if the geometry of the pattern approaches towards ;noninteracting conditions; (β > 1), when adsorption on each cell can be decoupled, approach of the coverage fraction θ(t) to θJ becomes closer to the exponential law. Consequently, changing the pattern parameters in the present model allows to interpolate the deposition kinetics between the continuum limit and the lattice-like behavior. Structural properties of the jammed-state coverings are studied in terms of the radial distribution function g(r) and spatial distribution of particles inside the cell. Various, non-trivial spatial distributions are observed depending on the geometry of the pattern.

  8. Suspension-firing of wood with coal ash addition: Probe measurements of ash deposit build-up at Avedøre Power Plant (AVV2)

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    This report is about full-scale probe measurements of deposit build-up and removal conducted at the Avedøreværket Unit 2, a 800 MWth suspension boiler, firing wood and natural gas with the addition of coal ash. Coal ash was used as an additive to capture potassium (K) from wood-firing. Investigat...... to the gas phase as HCl(g). Effect of boiler operational parameters on gas emissions has also been investigated.......This report is about full-scale probe measurements of deposit build-up and removal conducted at the Avedøreværket Unit 2, a 800 MWth suspension boiler, firing wood and natural gas with the addition of coal ash. Coal ash was used as an additive to capture potassium (K) from wood...... and boiler load on ash deposition propensity was investigated. Results of ash deposition propensity showed increasing trend with increasing flue gas temperature. Video monitoring revealed that the deposits formed were not sticky and could be easily removed, and even at very high flue gas temperatures (> 1350...

  9. Mobility and contamination assessment of mercury in coal fly ash, atmospheric deposition, and soil collected from Tianjin, China.

    Science.gov (United States)

    Wei, Zheng; Wu, Guanghong; Su, Ruixian; Li, Congwei; Liang, Peiyu

    2011-09-01

    Samples of class F coal fly ash (levels I, II, and III), slag, coal, atmospheric deposition, and soils collected from Tianjin, China, were analyzed using U.S. Environmental Protection Agency (U.S. EPA) Method 3052 and a sequential extraction procedure, to investigate the pollution status and mobility of Hg. The results showed that total mercury (HgT) concentrations were higher in level I fly ash (0.304 µg/g) than in level II and level III fly ash and slag (0.142, 0.147, and 0.052 µg/g, respectively). Total Hg in the atmospheric deposition was higher during the heating season (0.264 µg/g) than the nonheating season (0.135 µg/g). Total Hg contents were higher in suburban area soils than in rural and agricultural areas. High HgT concentrations in suburban area soils may be a result of the deposition of Hg associated with particles emitted from coal-fired power plants. Mercury in fly ash primarily existed as elemental Hg, which accounted for 90.1, 85.3, and 90.6% of HgT in levels I, II, and III fly ash, respectively. Mercury in the deposition existed primarily as sulfide Hg, which accounted for 73.8% (heating season) and 74.1% (nonheating season) of HgT. However, Hg in soils existed primarily as sulfide Hg, organo-chelated Hg and elemental Hg, which accounted for 37.8 to 50.0%, 31.7 to 41.8%, and 13.0 to 23.9% of HgT, respectively. The percentage of elemental Hg in HgT occurred in the order fly ash > atmospheric deposition > soils, whereas organo-chelated Hg and sulfide Hg occurred in the opposite order. The present approach can provide a window for understanding and tracing the source of Hg in the environment in Tianjin and the risk associated with Hg bioaccessibility. Copyright © 2011 SETAC.

  10. Fouling tendency of ash resulting from burning mixtures of biofuels. Part 2: Deposit chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mischa Theis; Bengt-Johan Skrifvars; Maria Zevenhoven; Mikko Hupa; Honghi Tranb [Aabo Akademi Process Chemistry Centre, Aabo (Finland). Combustion and Materials Chemistry

    2006-10-15

    Mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor under controlled conditions, and deposits were collected on an air-cooled probe at a temperature of 550 {sup o}C. The fuel and deposit compositions were compared using chemical fractionation analysis and SEM/EDX. Chemical fractionation analysis was capable of explaining the relative fouling tendency of peat, bark, and straw. The composition of deposits obtained from firing peat, bark, and straw individually resembled the composition of their ashes. When firing peat-bark and peat-straw mixtures, it was found that the deposition rate only started to increase when the Cl/S molar ratio in the feed ash exceeded 0.15. The composition of the ensuing deposits resembled the deposits obtained from burning either bark or straw individually. For peat-bark mixtures it was concluded that the presence of S in the feed suppresses deposition by sulfating chloride compounds, leading to deposits that contain less Cl and have less molten phase. For peat-straw mixtures it was concluded that the deposition behaviour is governed by other mechanisms than the interaction of Cl and S. 27 refs., 7 figs., 1 tab.

  11. Deposition and detection of particles during integrated circuit manufacturing

    NARCIS (Netherlands)

    Wali, F.; Knotter, D. Martin; Kelly, John J.; Kuper, F.G.

    2006-01-01

    Abstract—Deposition mechanism of silica particles on silicon wafers was investigated by depositing specially prepared mono-dispersed particles (mean diameter = 330 nm). To measure particles of the size below the detection limit of our particle measurement tools, silica particles with luminance core

  12. Utilization of power plant bottom-ash particles as stabilizer in aluminum foams

    Energy Technology Data Exchange (ETDEWEB)

    Asavavisithchai, Seksak; Prapajaraswong, Attanadol [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgical Engineering

    2013-07-01

    Aluminum foams, produced via powder metallurgical (PM) process, normally require the addition of ceramic particles in compaction stage, in order to increase both foamability of precursors and mechanical properties of the final foam products. Bottom ash particles are a by-product waste obtained from thermoelectric power plants which are commonly found to be used in landfill facilities. The major chemical constituent, approximately between 30 wt.-% and 60 wt.-%, of bottom ash particles is SiO{sub 2}, depending on chemical composition in coal, sintering condition and environment, and other process parameters. In this study, we explore the feasibility of utilizing bottom ash particles of thermoelectric power plant wastes as stabilizer in aluminum foams. A small amount of two-size bottom ash particles (mean size of 78 {mu}m and 186 {mu}m), between 1 wt.-% and 5 wt.-%, have been added to aluminum foams. Foam expansion, macro- and microstructures as well as mechanical properties, such as compressive strength and microhardness, were investigated. The results from the present study suggest that bottom ash particles can be used as a stabilizing material which can improve both cellular structure and mechanical properties of aluminum foams. (orig.)

  13. Furthering the investigation of eruption styles through quantitative shape analyses of volcanic ash particles

    Science.gov (United States)

    Nurfiani, D.; Bouvet de Maisonneuve, C.

    2018-04-01

    Volcanic ash morphology has been quantitatively investigated for various aims such as studying the settling velocity of ash for modelling purposes and understanding the fragmentation processes at the origin of explosive eruptions. In an attempt to investigate the usefulness of ash morphometry for monitoring purposes, we analyzed the shape of volcanic ash particles through a combination of (1) traditional shape descriptors such as solidity, convexity, axial ratio and form factor and (2) fractal analysis using the Euclidean Distance transform (EDT) method. We compare ash samples from the hydrothermal eruptions of Iwodake (Japan) in 2013, Tangkuban Perahu (Indonesia) in 2013 and Marapi (Sumatra, Indonesia) in 2015, the dome explosions of Merapi (Java, Indonesia) in 2013, the Vulcanian eruptions of Merapi in 2010 and Tavurvur (Rabaul, Papaua New Guinea) in 2014, and the Plinian eruption of Kelud (Indonesia) in 2014. Particle size and shape measurements were acquired from a Particle Size Analyzer with a microscope camera attached to the instrument. Clear differences between dense/blocky particles from hydrothermal or dome explosions and vesicular particles produced by the fragmentation of gas-bearing molten magma are well highlighted by conventional shape descriptors and the fractal method. In addition, subtle differences between dense/blocky particles produced by hydrothermal explosions, dome explosions, or quench granulation during phreatomagmatic eruptions can be evidenced with the fractal method. The combination of shape descriptors and fractal analysis is therefore potentially able to distinguish between juvenile and non-juvenile magma, which is of importance for eruption monitoring.

  14. Geochemically structural characteristics of municipal solid waste incineration fly ash particles and mineralogical surface conversions by chelate treatment.

    Science.gov (United States)

    Kitamura, Hiroki; Sawada, Takaya; Shimaoka, Takayuki; Takahashi, Fumitake

    2016-01-01

    Leaching behaviors of heavy metals contained in municipal solid waste incineration (MSWI) fly ash have been studied well. However, micro-characteristics of MSWI fly ash particles are still uncertain and might be non-negligible to describe their leaching behaviors. Therefore, this study investigated micro-characteristics of MSWI fly ash particles, especially their structural properties and impacts of chelate treatment on surface characteristics. According to SEM observations, raw fly ash particles could be categorized into four types based on their shapes. Because chelate treatment changed the surface of fly ash particles dramatically owing to secondary mineral formations like ettringite, two more types could be categorized for chelate-treated fly ash particles. Acid extraction experiments suggest that fly ash particles, tested in this study, consist of Si-base insoluble core structure, Al/Ca/Si-base semi-soluble matrices inside the body, and KCl/NaCl-base soluble aggregates on the surface. Scanning electron microscope (SEM) observations of the same fly ash particles during twice moistening treatments showed that KCl/NaCl moved under wet condition and concentrated at different places on the particle surface. However, element mobility depended on secondary mineral formations. When insoluble mineral like gypsum was generated and covered the particle surface, it inhibited element transfer under wet condition. Surface characteristics including secondary mineral formation of MSWI fly ash particles are likely non-negligible to describe trace element leaching behaviors.

  15. Numerical investigation of ash deposition in straw-fired boilers

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    in the design phase of straw-fired boilers. Some of the primary model outputs include improved heat transfer rate predictions and detailed information about local deposit formation rates. This information is essential when boiler availability and efficiency is to be estimated. A stand-alone program has been...... accumulation rates encountered during straw combustion in grate-fired boilers. The sub-models have been based on information about the combustion and deposition properties of straw gathered from the literature and combined into a single Computational Fluid Dynamics (CFD) based analysis tool which can aid...... transfer mechanisms have a pronounced influence on the combustion pattern. The combined set of sub-models has been evaluated using the straw-fired boiler at Masnedø CHP plant as a test case. The predicted grate combustion and KCl release patterns are in qualitative agreement with experimental findings...

  16. Sulfur retention by ash during coal combustion. Part I. A model of char particle combustion

    Directory of Open Access Journals (Sweden)

    BORISLAV GRUBOR

    2003-02-01

    Full Text Available A model for the combustion of porous char particles as a basis for modeling the process of sulfur retention by ash during coal combustion is developed in this paper. The model belongs to the microscopic intrinsic models and describes the dynamic behavior of a porous char particle during comustion, taking into account temporal and spatial changes of all important physical properties of the char particle and various combustion parameters. The parametric analysis of the enhanced model shows that the model represents a good basis for the development of a model for the process of sulfur retention by ash during coal combustion. The model enables the prediction of the values of all parameters necessary for the introduction of reactions between sulfur compounds and mineral components in ash, primarily calcium oxide.

  17. Ash deposition and high temperature corrosion at combustion of aggressive fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hede Larsen, O [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Henriksen, N [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    In order to reduce CO{sub 2} emission, ELSAM is investigating the possibilities of using biomass - mainly straw - for combustion in high efficiency power plants. As straw has very high contents of chlorine and potassium, a fuel with high corrosion and ash deposition propensities has been introduced. ELSAM has investigated 3 ultra supercritical boiler concepts for combustion of straw alone or together with coal: (1) PF boilers with a relatively low share of straw, (2) CFB boilers with low to high share of straw and (3) vibrating grate boilers with 100% straw. These investigations has mainly been full-scale tests with straw fed into existing boilers. Corrosion tests have been performed in these boilers using temperature regulated probes and in-plant test tubes in existing superheaters. The corrosion has been determined by detailed measurements of wall thickness reduction and light optical microscopic measurements of the material degradation due to high temperature corrosion. Corrosion mechanisms have been evaluated using SEM/EDX together with thermodynamical considerations based on measurements of the chemical environment in the flue gas. Ash deposition is problematic in CFB boilers and in straw fired boilers, especially in years with high potassium and chlorine content of the straw. This ash deposition also is related to condensation of KCl and can probably only be handled by improved cleaning devices. (EG)

  18. The characteristics and application of sludge-fly ash ceramic particles (SFCP) as novel filter media

    International Nuclear Information System (INIS)

    Han Shuxin; Yue Qinyan; Yue Min; Gao Baoyu; Li Qian; Yu Hui; Zhao Yaqin; Qi Yuanfeng

    2009-01-01

    Novel filter media-sludge-fly ash ceramic particles (SFCP) were prepared using dewatered sludge, fly ash and clay with a mass ratio of 1:1:1. Compared with commercial ceramic particles (CCP), SFCP had higher total porosity, larger total surface area and lower bulk and apparent density. Tests of heavy metal elements in lixivium proved that SFCP were safe for wastewater treatment. A lab-scale upflow anaerobic bioreactor was employed to ascertain the application of SFCP in denitrification process using acetate as carbon source. The results showed that SFCP reactor brought a relative superiority to CCP reactor in terms of total nitrogen (TN) removal at the optimum C/N ratio of 4.03 when volumetric loading rates (VLR) ranged from 0.33 to 3.69 kg TN (m 3 d) -1 . Therefore, SFCP application, as a novel process of treating wastes with wastes, provided a promising way in sludge and fly ash utilization.

  19. Hybrid micro-particles as a magnetically-guidable decontaminant for cesium-eluted ash slurry

    Science.gov (United States)

    Namiki, Yoshihisa; Ueyama, Toshihiko; Yoshida, Takayuki; Watanabe, Ryoei; Koido, Shigeo; Namiki, Tamami

    2014-09-01

    Decontamination of the radioactive cesium that is widely dispersed owing to a nuclear power station accident and concentrated in fly ash requires an effective elimination system. Radioactive fly ash contains large amounts of water-soluble cesium that can cause severe secondary contamination and represents a serious health risk, yet its complete removal is complicated and difficult. Here it is shown that a new fine-powder formulation can be magnetically guided to eliminate cesium after being mixed with the ash slurry. This formulation, termed MagCE, consists of a ferromagnetic porous structure and alkaline- and salt-resistant nickel ferrocyanide. It has potent cesium-adsorption- and magnetic-separation-properties. Because of its resistance against physical and chemical attack such as with ash particles, as well as with the high pH and salt concentration of the ash slurry, MagCE simplifies the decontamination process without the need of the continued presence of the hazardous water-soluble cesium in the treated ash.

  20. Scattering matrices of volcanic ash particles of Mount St. Helens, Redoubt, and Mount Spurr Volcanoes

    NARCIS (Netherlands)

    Munoz, O.; Volten, H.; Hovenier, J.W.; Veihelmann, B.; Zande, W.J. van der; Waters, L.; Rose, W.I.

    2004-01-01

    [1] We present measurements of the whole scattering matrix as a function of the scattering angle at a wavelength of 632.8 nm in the scattering angle range 3degrees - 174degrees of randomly oriented particles taken from seven samples of volcanic ashes corresponding to four different volcanic

  1. Scattering matrices of volcanic ash particles of Mount St. Helens, Redoubt, and Mount Spurr Volcanoes

    NARCIS (Netherlands)

    Muñoz, O.; Volten, H.; Hovenier, J.W.; Veihelmann, B.; van der Zande, W.J.; Waters, L.B.F.M.; Rose, W.I.

    2004-01-01

    We present measurements of the whole scattering matrix as a function of the scattering angle at a wavelength of 632.8 nm in the scattering angle range 3°-174° of randomly oriented particles taken from seven samples of volcanic ashes corresponding to four different volcanic eruptions: the 18 May 1980

  2. Dynamics of deposited fly-ash and fine grained magnetite in sandy material of different porosity (column experiments)

    Science.gov (United States)

    Kapicka, Ales; Kodesova, Radka; Petrovsky, Eduard; Grison, Hana

    2010-05-01

    Several studies confirm that soil magnetometry can serve as proxy of industrial immisions as well as heavy-metal contamination. The important assumption for magnetic mapping of contaminated soils is that atmospherically deposited particulate matter, including the ferrimagnetic phase, accumulates in the top soil horizons and remains there over long period. Only if this is true, large areas can be reliably mapped using soil magnetometry, and, moreover, this method can be used also for long-term monitoring. However, in soil types such as sandy soils with different porosity or soils with substantial variability of water regime, translocation of the deposited anthropogenic particles may result in biased (underestimated) values of the measured topsoil magnetic susceptibility. From the physical point of view, this process may be considered as colloid transport through porous medium. In our column experiments in laboratory we used three technical sands with different particle sizes (0,63 - 1.25mm, 0,315-0,80mm, 0,10-0,63mm). Sands in cylinders were contaminated on the surface by fly-ashes from coal-burning power plant (mean grain size 10μm) and fine grained Fe3O4 (grain size < 20 μm). Soil moisture sensors were used to monitor water regime within the sand columns after controlled rain simulation and temperature distribution in sand column was measured as well. Vertical migration of ferrimagnetic particles-tracers presented in the fly-ash was measured by SM 400 Kappameter. By means of magnetic susceptibility distribution we studied two parameters: gradual shift of peak concentration of contaminants (relative to surface layer) and maximum penetration depth. Results indicated that after rain simulation (pulls infiltration of defined water volume) the positions of peak values moved downwards compared to the initial state and gradual decrease of susceptibility peak values were detected in all studied sand formations. Fly-ash migrated more or less freely in coarse sand

  3. Effects of temperature and particle size on deposition in land based turbines - article no. 051503

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, J.M.; Lewis, S.; Bons, J.P.; Ai, W.G.; Fletcher, T.H. [Brigham Young University, Provo, UT (United States). Dept. for Mechanical Engineering

    2008-09-15

    Four series of tests were performed in an accelerated deposition test facility to study the independent effects of particle size, gas temperature, and metal temperature on ash deposits from two candidate power turbine synfuels (coal and petcoke). The facility matches the gas temperature and velocity of modern first stage high pressure turbine vanes while accelerating the deposition process. Particle size was found to have a significant effect on capture efficiency with larger particles causing significant thermal barrier coating (TBC) spallation during a 4 h accelerated test. In the second series of tests, particle deposition rate was found to decrease with decreasing gas temperature. The threshold gas temperature for deposition was approximately 960{sup o}C. In the third and fourth test series, impingement cooling was applied to the back side of the target coupon to simulate internal vane cooling. Capture efficiency was reduced with increasing mass flow of coolant air; however, at low levels of cooling, the deposits attached more tenaciously to the TBC layer. Postexposure analyses of the third test series (scanning electron microscopy and X-ray spectroscopy) show decreasing TBC damage with increased cooling levels.

  4. Insights into the Toba Super-Eruption using SEM Analysis of Ash Deposits

    Science.gov (United States)

    Gatti, E.; Achyuthan, H.; Durant, A. J.; Gibbard, P.; Mokhtar, S.; Oppenheimer, C.; Raj, R.; Shridar, A.

    2010-12-01

    The ~74 ka Youngest Toba Tuff (YTT) super-eruption of Toba volcano, Northern Sumatra, was the largest eruption of the Quaternary (magnitude M= 8.8) and injected massive quantities of volcanic gases and ash into the stratosphere. YTT deposits covered at least 40,000,000 km2 of Southeast Asia and are preserved in river valleys across peninsular India and Malaysia, and in deep-sea tephra layers in the Indian Ocean, Bay of Bengal and South China Sea. Initial studies hypothesized the eruption caused immediate and substantial global cooling during the ~ 1 kyr between Dansgaard-Oeschger events 19 and 20 which devastated ecosystems and hominid populations. A more recent review argues against severe post-YTT climatic deterioration and cannot find clear evidence for considerable impacts on ecosystems or bio-diversity. The determination of the eruptive parameters is crucial in this issue to document the eruption and understand the potential impacts from future super-volcanic eruptions. Volcanic ash deposits can offer dramatic insights into key eruptive parameters, including magnitude, duration and plume height. The composition and shape of volcanic ashes can be used to interpret physical properties of an erupting magma and tephra transport, while textural characteristics such as grain roughness and surface vescicularity can provide insights into degassing history, volatile content and explosive activity of the volcano. We present a stratigraphic and sedimentological analysis of YTT deposits in stratified contexts at three localities in India, at two sites in Peninsular Malaysia, and at several localities around Lake Toba and on Samosir Island, Sumatra. These sites offer excellent constraints on the spatial distribution of YTT deposits which can be used to infer dispersal directions of the cloud, and provide insights into environmental controls on preservation of tephra beds. The research aims at a systematic interpretation of the Toba tephra to understand the volcanic

  5. Experimental investigation of ash deposits characteristics of co-combustion of coal and rice hull using a digital image technique

    International Nuclear Information System (INIS)

    Qiu, Kunzan; Zhang, Hailong; Zhou, Hao; Zhou, Bin; Li, Letian; Cen, Kefa

    2014-01-01

    This paper investigated the ash deposit characteristics during the co-firing Da Tong (DA) coal with different proportions of rice hull (0%, 5%, 10%, and 20%, based on weight) in a pilot-scale furnace. The growth of ash deposit with a four-stage mode was presented. The stable thickness values of DA coal, 5% rice hull, 10% rice hull, and 20% rice hull were 0.5, 1.4, 2.9, 5.7 cm, with stable heat flux values of 230, 200, 175, and 125 kW/m 2 , respectively. According to the results of scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), the amount of Si in the deposits increased with the increasing proportion of rice hull rich in SiO 2 . The X-ray diffraction (XRD) analysis results indicated that most elements except Si were in the amorphous state because of the formation of eutectics. The stable thicknesses of deposits increased exponentially with the proportion of rice hull. The deposit was loose, easy removable but it reduced the heat transfer significantly. Consequently, sootblowing timely was necessary when co-firing DA coal with rice hull. - Highlights: • Digital image technique was used to monitor deposits growth process. • A type of four stages mode of ash deposit growth was presented. • The heat flux of ash deposits fit a three-stage mode. • The addition of rice hull increased the porosity of deposits

  6. Conditions and timescales for welding block-and-ash flow deposits

    Science.gov (United States)

    Heap, M. J.; Kolzenburg, S.; Russell, J. K.; Campbell, M. E.; Welles, J.; Farquharson, J. I.; Ryan, A.

    2014-12-01

    Welding of pyroclastic deposits to reform a coherent rock mass is a common phenomenon, especially for pumiceous pyroclastic density current deposits (i.e., ignimbrites). However, and despite the pervasive abundance of block-and-ash flow (BAF) deposits in the geological and modern record, instances of strongly welded BAF deposits are few. Here, we present a series of high-temperature (800-900 °C) compaction experiments designed to map the conditions (deposit thickness/stress and temperature/viscosity) and timescales that permit or inhibit the welding of BAF deposits. Our experiments were performed on unconsolidated aggregates (containing an ash and lapilli component) derived from crushed and sieved lava blocks (containing 25% crystals) taken from the well-documented welded BAF deposit at Mount Meager volcano (British Columbia, Canada). The experiments demonstrate that welding efficiency increases with increasing time and temperature. Progressive welding is expressed by increasing axial strain, porosity loss, and bulk density. The rate of change of each of these physical properties reduces as welding progresses. Microstructural analysis of the experimental products shows that the loss of interclast porosity during welding results from the progressive sintering and amalgamation of vitric fragments, and that the pore shape changes from sub-equant pores to stretched lenses sandwiched between vitric and crystal fragments. The coincidence between the microstructure and rock physical properties of the natural and experimental samples highlight that we have successfully reproduced welded BAF in the laboratory. Furthermore, our permeability measurements highlight a hysteresis in the return journey of the "there-and-back-again" volcanic permeability cycle (expressed by an increase in permeability due to vesiculation and fragmentation followed by a decrease due to welding). This hysteresis cannot be described by a single porosity-permeability power law relationship and

  7. Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

    Science.gov (United States)

    Várai, A.; Vincze, M.; Lichtenberger, J.; Jánosi, I. M.

    2011-12-01

    Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

  8. Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

    International Nuclear Information System (INIS)

    Várai, A; Vincze, M; Jánosi, I M; Lichtenberger, J

    2011-01-01

    Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

  9. Ash Deposit Formation and Removal in a Straw and Wood Suspension-Fired Boiler

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    ). The shedding investigation was also made when the nearby plant sootblower (4m below) was working. It was identified that the mass uptake signal remained stable and the deposits in small pieces were continuously removed during 35% and 65% straw-firing. Previous findings of Vattenfall indicated that a mixture...... was limited to two weeks when 100% straw was fired due to ash deposition in the superheater region that has tube spacing specified for coal-firing (113mm). A series of 3-5 days deposit probe experiments were conducted utilizing 35 to 100% straw with wood on mass basis. The applied deposit probe was water...... two hours deposit mass uptake rate was 52.8 (g/m2/h), while it was 353.8 (g/m2/h) during 100% straw-firing. All tests in the superheater region for all applied straw shares indicated that with increase in straw share, final deposit mass uptake increased. The comparison of current and previous full...

  10. COPDIRC - calculation of particle deposition in reactor coolants

    International Nuclear Information System (INIS)

    Reeks, M.W.

    1982-06-01

    A description is given of a computer code COPDIRC intended for the calculation of the deposition of particulate onto smooth perfectly sticky surfaces in a gas cooled reactor coolant. The deposition is assumed to be limited by transport in the boundary layer adjacent to the depositing surface. This implies that the deposition velocity normalised with respect to the local friction velocity, is an almost universal function of the normalised particle relaxation time. Deposition is assumed similar to deposition in an equivalent smooth perfectly absorbing pipe. The deposition is calculated using 2 models. (author)

  11. Immersion Freezing of Coal Combustion Ash Particles from the Texas Panhandle

    Science.gov (United States)

    Whiteside, C. L.; Tobo, Y.; Mulamba, O.; Brooks, S. D.; Mirrielees, J.; Hiranuma, N.

    2017-12-01

    Coal combustion aerosol particles contribute to the concentrations of ice-nucleating particles (INPs) in the atmosphere. Especially, immersion freezing can be considered as one of the most important mechanisms for INP formation in supercooled tropospheric clouds that exist at temperatures between 0°C and -38°C. The U.S. contains more than 550 operating coal-burning plants consuming 7.2 x 108 metric tons of coal (in 2016) to generate a total annual electricity of >2 billion MW-h, resulting in the emission of at least 4.9 x 105 metric tons of PM10 (particulate matter smaller than 10 µm in diameter). In Texas alone, 19 combustion plants generate 0.15 billion MW-h electricity and >2.4 x 104 metric tons of PM10. Here we present the immersion freezing behavior of combustion fly ash and bottom ash particles collected in the Texas Panhandle region. Two types of particulate samples, namely electron microscopy on both ash types will also be presented to relate the crystallographic and chemical properties to their ice nucleation abilities.

  12. In-situ observations of Eyjafjallajökull ash particles by hot-air balloon

    Science.gov (United States)

    Petäjä, T.; Laakso, L.; Grönholm, T.; Launiainen, S.; Evele-Peltoniemi, I.; Virkkula, A.; Leskinen, A.; Backman, J.; Manninen, H. E.; Sipilä, M.; Haapanala, S.; Hämeri, K.; Vanhala, E.; Tuomi, T.; Paatero, J.; Aurela, M.; Hakola, H.; Makkonen, U.; Hellén, H.; Hillamo, R.; Vira, J.; Prank, M.; Sofiev, M.; Siitari-Kauppi, M.; Laaksonen, A.; lehtinen, K. E. J.; Kulmala, M.; Viisanen, Y.; Kerminen, V.-M.

    2012-03-01

    The volcanic ash cloud from Eyjafjallajökull volcanic eruption seriously distracted aviation in Europe. Due to the flight ban, there were only few in-situ measurements of the properties and dispersion of the ash cloud. In this study we show in-situ observations onboard a hot air balloon conducted in Central Finland together with regional dispersion modelling with SILAM-model during the eruption. The modeled and measured mass concentrations were in a qualitative agreement but the exact elevation of the layer was slightly distorted. Some of this discrepancy can be attributed to the uncertainty in the initial emission height and strength. The observed maximum mass concentration varied between 12 and 18 μg m -3 assuming a density of 2 g m -3, whereas the gravimetric analysis of the integrated column showed a maximum of 45 μg m -3 during the first two descents through the ash plume. Ion chromatography data indicated that a large fraction of the mass was insoluble to water, which is in qualitative agreement with single particle X-ray analysis. A majority of the super-micron particles contained Si, Al, Fe, K, Na, Ca, Ti, S, Zn and Cr, which are indicative for basalt-type rock material. The number concentration profiles indicated that there was secondary production of particles possibly from volcano-emitted sulfur dioxide oxidized to sulfuric acid during the transport.

  13. Deposition of fine and ultrafine particles on indoor surface materials

    DEFF Research Database (Denmark)

    Afshari, Alireza; Reinhold, Claus

    2008-01-01

    -scale test chamber. Experiments took place in a 32 m3 chamber with walls and ceiling made of glass. Prior to each experiment the chamber was flushed with outdoor air to reach an initial particle concentration typical of indoor air in buildings with natural ventilation. The decay of particle concentrations...... The aim of this study was the experimental determination of particle deposition for both different particle size fractions and different indoor surface materials. The selected surface materials were glass, gypsum board, carpet, and curtain. These materials were tested vertically in a full...... was monitored. Seven particle size fractions were studied. These comprised ultrafine and fine particles. Deposition was higher on carpet and curtain than on glass and gypsum board. Particles ranging from 0.3 to 0.5 µm had the lowest deposition. This fraction also has the highest penetration and its indoor...

  14. Characterization of triboelectrically charged particles deposited on dielectric surfaces

    Science.gov (United States)

    Nesterov, A.; Löffler, F.; Cheng, Yun-Chien; Torralba, G.; König, K.; Hausmann, M.; Lindenstruth, V.; Stadler, V.; Bischoff, F. R.; Breitling, F.

    2010-04-01

    A device for the measurement of q/m-values and charge degradation of triboelectrically charged particles deposited on a surface was developed. The setup is based on the integration of currents, which are induced in a Faraday cage by insertion of a solid support covered with charged particles. The conductivity of different particle supports was taken into account. The 'blow-off' method, in which the particles are first deposited, and then blown off using an air stream, can be used for characterization of triboelectric properties of particles relative to different surfaces.

  15. Characterization of triboelectrically charged particles deposited on dielectric surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nesterov, A; Torralba, G; Hausmann, M; Lindenstruth, V [Kirchhoff Institute of Physics, In Neuenheimer Feld 227, Heidelberg (Germany); Loeffler, F; Cheng, Yun-Chien; Koenig, K; Stadler, V; Bischoff, F R [German Cancer Research Centre, In Neuenheimer Feld 280, Heidelberg (Germany); Breitling, F, E-mail: Frank.Breitling@KIT.ed, E-mail: alexander.nesterov-mueller@kit.ed [Karlsruhe Institute of Technology (KIT), Institute for Microstructure Technology, Herrmann von Helmholtzplatz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2010-04-28

    A device for the measurement of q/m-values and charge degradation of triboelectrically charged particles deposited on a surface was developed. The setup is based on the integration of currents, which are induced in a Faraday cage by insertion of a solid support covered with charged particles. The conductivity of different particle supports was taken into account. The 'blow-off' method, in which the particles are first deposited, and then blown off using an air stream, can be used for characterization of triboelectric properties of particles relative to different surfaces.

  16. The dissolution kinetics of major elements in municipal solid waste incineration bottom ash particles

    Science.gov (United States)

    Bendz, David; Tüchsen, Peter L.; Christensen, Thomas H.

    2007-12-01

    Leaching and tracer experiments in batches at L/S 20 were performed with 3-month-old MSWI bottom ash separated into eight different particle sizes. The time-dependent leaching of major elements (Ca 2+, K +, Na +, Cl - and SO 4- 2 ) was monitored for up to 747 h. Physical properties of the particles, the specific surface (BET), pore volume and pore volume distribution over pore sizes (BJH) were determined for all particle classes by N 2 adsorption/desorption experiments. Some common features of physical pore structure for all particles were revealed. The specific surface and the particle pore volume were found to be negatively correlated with particle size, ranging from 3.2 m 2/g to 25.7 m 2/g for the surface area and from 0.0086 cm 3/g to 0.091 cm 3/g for the pore volume. Not surprisingly, the specific surface area was found to be the major material parameter that governed the leaching behavior for all elements (Ca 2+, K +, Na +, Cl - and SO 4- 2 ) and particle sizes. The diffusion resistance was determined independently by separate tracer (tritium) experiments. Diffusion gave a significant contribution to the apparent leaching kinetics for all elements during the first 10-40 h (depending on the particle size) of leaching and surface reaction was the overall rate controlling mechanism at late times for all particle sizes. For Ca 2+ and SO 4- 2 , the coupled effect of diffusion resistance and the degree of undersaturation in the intra particle pore volume was found to be a major rate limiting dissolution mechanism for both early and late times. The solubility control in the intra particulate porosity may undermine any attempt to treat bottom ash by washing out the sulfate. Even for high liquid/solid ratios, the solubility in the intra-particular porosity will limit the release rate.

  17. The trapping of fly-ash particles in the surface layers of Sphagnum-dominated peat

    International Nuclear Information System (INIS)

    Punning, J.-M.; Alliksaar, T.

    1997-01-01

    The movement of fly-ash particles in a sequence of Sphagnum moss was studied in laboratory experiments and field investigations. Fly ash was obtained from the electrostatic precipitators of the Estonian Thermal Power Plant operating on oil shale. The data obtained in the laboratory show that only 0.8% of particles, placed on the surface of a 6-10 cm thick Sphagnum layer, were washed out with water (700-750 mm) during the 241 days of the experiment. The majority of added particles were fixed in the upper part (90% in 1-3 cm) of the moss layer. A SEM study indicates that sorption is slightly species-dependent due to the micromorphological parameters of the Sphagnum species. The storage of particles by Sphagnum mosses allows the use of natural sequences to study the history of atmospheric pollution. The distribution of particles in the upper part of moss layers in Viru Bog (50 km east of Tallinn, North Estonia) shows good agreement with the known air pollution history in Tallinn. 13 refs., 6 figs., 2 tabs

  18. Modeling airflow and particle transport/deposition in pulmonary airways.

    Science.gov (United States)

    Kleinstreuer, Clement; Zhang, Zhe; Li, Zheng

    2008-11-30

    A review of research papers is presented, pertinent to computer modeling of airflow as well as nano- and micron-size particle deposition in pulmonary airway replicas. The key modeling steps are outlined, including construction of suitable airway geometries, mathematical description of the air-particle transport phenomena and computer simulation of micron and nanoparticle depositions. Specifically, diffusion-dominated nanomaterial deposits on airway surfaces much more uniformly than micron particles of the same material. This may imply different toxicity effects. Due to impaction and secondary flows, micron particles tend to accumulate around the carinal ridges and to form "hot spots", i.e., locally high concentrations which may lead to tumor developments. Inhaled particles in the size range of 20nm< or =dp< or =3microm may readily reach the deeper lung region. Concerning inhaled therapeutic particles, optimal parameters for mechanical drug-aerosol targeting of predetermined lung areas can be computed, given representative pulmonary airways.

  19. Possibilities for stabilization of fly ash from REK 'Bitola' dump

    International Nuclear Information System (INIS)

    Petrushevska, Ljubica; Ivanovska, Pavlina; Ilievski, Zlatko; Peeva, Liljana

    2002-01-01

    The Coal Power Plants environmental problems, mainly, arise from deposited fly ash-solid particles which, under the influence of the wind, heavily pollute the atmospheric air. Prevention of the environmental problems, coming from spraying from the energetic dumps, is achieved with technical and biological stabilization of dumped fly ash. The choice of the stabilization means and methods depends on the physical-chemical properties of the ash. Therefore, the stabilization possibilities of REK 'Bitola' fly ash were investigated. (Original)

  20. Factors affecting on the particle deposition in the respiratory tract

    International Nuclear Information System (INIS)

    Kubota, Yoshihisa

    1991-01-01

    The deposition pattern of inhaled particles in the respiratory tracts is affected by anatomical structure of the respiratory tracts and respiratory pattern of animals, which are modified by many factors as animal species, physiological and psychological conditions, age, sex, smoking drug, lung diseases, etc. In human, studies have been focused on the initial lung deposition of particles and have made it clear that the respiratory pattern, gender, and diseases may have influence on the deposition pattern. On the other hand, there was little knowledge on the initial lung deposition of particles in laboratory animals. Recently, Raabe et al. have reported the initial lung deposition of 169 Yb-aluminosilicate particles in mice, rats, hamsters, guinea pigs and rabbits. The authors have also investigated the lung deposition of latex particles with different sizes and 198 Au-colloid in rats whose respiratory volumes during the inhalation were monitored by body plethysmography. These experiments indicated that the deposition of inhaled particles in distal lung e.g. small bronchiolar and alveolar region, was much lower in laboratory animals than that of human. This species difference may be due to smaller diameter of respiratory tract and/or shallower breathing and higher respiratory rate of laboratory animals. The experimental animals in which respiratory diseases were induced artificially have been used to investigate the modification factors on the deposition pattern of inhaled particles. As respiratory diseases, emphysema was induced in rats, hamsters, beagle dogs in some laboratories and pulmonary delayed type hypersensitivity reaction in rats was in our laboratory. The initial lung deposition of particles in these animals was consistently decreased in comparison with normals, regardless of the animal species and the type of disease. (author)

  1. On moistening of ash particles in smoke plumes of industrial sources

    International Nuclear Information System (INIS)

    Geints, Yu.E.; Zemlyanov, A.A.

    1992-01-01

    Moistening of ash particles occurring in the humid atmosphere is one of the main factors decreasing the accuracy of the lidar measurements of thickness of smoke emissions. Theoretical investigation of the growth of water coating of smoke particles under different meteorological conditions within the zone of emission has been carried out based on the Gaussian model of smoke plume with slant axis and its parameters. Numerical calculations have shown that in the case of high initial moisture content of the emissions near the source in the smoke plume the zone appears in which water vapor is supersaturated and the effect of particle moistening is significant. Seasonal trends and diurnal variations in temperature and humidity in the surface layer of the atmosphere also substantially affect moistening. Length of the zone of moistening of ash particles is maximum at night in winter under conditions of light breeze. The possibility of retrieving the initial mass concentration of the dry aerosol in the smoke plume has been shown based on lidar measurements of the scattering coefficient within the zone of maximum degree of moistening of smoke plume. 10 refs., 5 figs

  2. Unsteady Particle Deposition in a Human Nasal Cavity during Inhalation

    Directory of Open Access Journals (Sweden)

    Camby M.K. Se

    2010-12-01

    Full Text Available The present study investigates the deposition efficiency during the unsteady inhalation cycle by using Computational Fluid Dynamics (CFD. The unsteady inhalation profile was applied at the outlet of nasopharynx, which had a maximum flow rate of 40.3L/min which corresponds to an equivalent steady inhalation tidal volume flow rate of 24.6L/min. Aerodynamic particle sizes of 5μm and 20μm were studied in order to reflect contrasting Stokes numbered particle behaviour. Two particle deposition efficiencies in the nasal cavity versus time are presented. In general, the deposition of 5μm particles was much less than 20μm particles. The first 0.2 second of the inhalation cycle was found to be significant to the particle transport, since the majority of particles were deposited during this period (i.e. its residence time. Comparisons were also made with its equivalent steady inhalation flow rate which found that the unsteady inhalation produced lower deposition efficiency for both particle sizes.

  3. Increased sensitivity in thick-target particle induced X-ray emission analyses using dry ashing for preconcentration

    International Nuclear Information System (INIS)

    Lill, J.-O.; Harju, L.; Saarela, K.-E.; Lindroos, A.; Heselius, S.-J.

    1999-01-01

    The sensitivity in thick-target particle induced X-ray emission (PIXE) analyses of biological materials can be enhanced by dry ashing. The gain depends mainly on the mass reduction factor and the composition of the residual ash. The enhancement factor was 7 for the certified reference material Pine Needles and the limits of detection (LODs) were below 0.2 μg/g for Zn, Cu, Rb and Sr. When ashing biological materials with low ash contents such as wood of pine or spruce (0.3% of dry weight) and honey (0.1% of wet weight) the gain was far greater. The LODs for these materials were 30 ng/g for wood and below 10 ng/g for honey. In addition, the ashed samples were more homogenous and more resistant to changes during the irradiation than the original biological samples. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. A new approach for modeling dry deposition velocity of particles

    Science.gov (United States)

    Giardina, M.; Buffa, P.

    2018-05-01

    The dry deposition process is recognized as an important pathway among the various removal processes of pollutants in the atmosphere. In this field, there are several models reported in the literature useful to predict the dry deposition velocity of particles of different diameters but many of them are not capable of representing dry deposition phenomena for several categories of pollutants and deposition surfaces. Moreover, their applications is valid for specific conditions and if the data in that application meet all of the assumptions required of the data used to define the model. In this paper a new dry deposition velocity model based on an electrical analogy schema is proposed to overcome the above issues. The dry deposition velocity is evaluated by assuming that the resistances that affect the particle flux in the Quasi-Laminar Sub-layers can be combined to take into account local features of the mutual influence of inertial impact processes and the turbulent one. Comparisons with the experimental data from literature indicate that the proposed model allows to capture with good agreement the main dry deposition phenomena for the examined environmental conditions and deposition surfaces to be determined. The proposed approach could be easily implemented within atmospheric dispersion modeling codes and efficiently addressing different deposition surfaces for several particle pollution.

  5. Separation and chemical characterization of finely-sized fly-ash particles

    International Nuclear Information System (INIS)

    Campbell, J.A.; Laul, J.C.; Nielson, K.K.; Smith, R.D.

    1978-01-01

    The concentrations of 43 major, minor, and trace elements were measured by x-ray fluorescence, atomic absorption, and instrumental neutron activation for nine well-defined size fractions, with mass median diameters of 0.5 μ to 50 μm, of fly ash from a western coal-fired steam plant. There was generally good agreement in concentrations of elements analyzed by more than one technique. Concentration profiles as a function of mean particle size were established for various elements. Based on the concentration profiles, the elements can be divided into three distinct groups. One group consists primarily of the volatile elements or elements partially volatilized during coal combustion (examples include As, Se, Zn, Ga, etc.), and their concentrations decrease with increasing particle size. A second group, which shows a minor or direct dependence on particle size, as in the case of Si, is apparently associated primarily with the fly-ash matrix. The last group of elements, which includes Ca, Sr, Y, and the rare earths, shows small changes in their concentration profiles with a maximum in concentration at approximately 5 μm. 6 tables, 6 figures

  6. EFFECT OF BODY SIZE ON BREATHING PATTERN AND FINE PARTICLE DEPOSITION IN CHILDREN

    Science.gov (United States)

    Inter-child variability in breathing patterns may contribute to variability in fine particle, lung deposition and morbidity in children associated with those particles. Fractional deposition (DF) of fine particles (2um monodisperse, carnauba wax particles) was measured in healthy...

  7. Transient Simulation of Accumulating Particle Deposition in Pipe Flow

    Science.gov (United States)

    Hewett, James; Sellier, Mathieu

    2015-11-01

    Colloidal particles that deposit in pipe systems can lead to fouling which is an expensive problem in both the geothermal and oil & gas industries. We investigate the gradual accumulation of deposited colloids in pipe flow using numerical simulations. An Euler-Lagrangian approach is employed for modelling the fluid and particle phases. Particle transport to the pipe wall is modelled with Brownian motion and turbulent diffusion. A two-way coupling exists between the fouled material and the pipe flow; the local mass flux of depositing particles is affected by the surrounding fluid in the near-wall region. This coupling is modelled by changing the cells from fluid to solid as the deposited particles exceed each local cell volume. A similar method has been used to model fouling in engine exhaust systems (Paz et al., Heat Transfer Eng., 34(8-9):674-682, 2013). We compare our deposition velocities and deposition profiles with an experiment on silica scaling in turbulent pipe flow (Kokhanenko et al., 19th AFMC, 2014).

  8. Uranium trace and alpha activity characterization of coal and fly ash using particle track etch technique

    International Nuclear Information System (INIS)

    Chakravarti, S.K.

    1991-01-01

    Uranium is extensively found in carbonaceous components of sedimentary rocks and is considered to be accumulated in coals during the coalification process through the geological times. Burning of coal is mainly responsible for a manifold increase in the concentration of radioactive nuclides in atmosphere precipitates. Fly ash being an incombustible residue and formed from 90% of the inorganic material in coal, escapes into the atmosphere and constitutes a potential hazard. Also its use as one of the pozzolanic materials in the products of concrete, bricks etc and filling of ground cavities is even more hazardous because of the wall radioactivity, besides emission and diffusion of radon. This paper reports a simple method called Particle Track Etch (PTE) technique, for trace determination of uranium content in coal and fly ash samples by making use of low cost and versatile plastic detectors known as Solid State Nuclear Track Detectors (SSNTDs). Total alpha activity has also been estimated using these SSNTDs. The values of uranium concentration in coal samples are found to range from 1.1 to 3.6 ppm (uniform component) and 33 to 46 ppm (non-uniform part) whereas in fly ash, it varies from 8 to 11 ppm (uniform) and 55 to 71 ppm in non-uniform range. It is also observed that the alpha activity is a function of uranium concentration for most of the natural samples of coal studied except for mixtures of fly ash samples where relationship is found to be on higher side. (author). 13 refs., 2 tabs., 1 fig

  9. Gold particle formation via photoenhanced deposition on lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Zaniewski, A.M., E-mail: azaniews@asu.edu; Meeks, V.; Nemanich, R.J.

    2017-05-31

    Highlights: • Gold chloride is reduced into solid gold nanoparticles at the surface of a polarized semiconductor. • Reduction processes are driven by ultraviolet light. • Gold nanoparticle and silver nanoparticle deposition patterns are compared. - Abstract: In this work, we report on a technique to reduce gold chloride into sub-micron particles and nanoparticles. We use photoelectron transfer from periodically polarized lithium niobate (PPLN) illuminated with above band gap light to drive the surface reactions required for the reduction and particle formation. The particle sizes and distributions on the PPLN surface are sensitive to the solution concentration, with inhibited nucleation and large particles (>150 nm) for both low (2E−8M to 9E−7M) and high (1E−5M to 1E−3M) concentrations of gold chloride. At midrange values of the concentration, nucleation is more frequent, resulting in smaller sized particles (<150 nm). We compare the deposition process to that for silver, which has been previously studied. We find that the reduction of gold chloride into nanoparticles is inhibited compared to silver ion reduction, due to the multi-step reaction required for gold particle formation. This also has consequences for the resulting deposition patterns: while silver deposits into nanowires along boundaries between areas with opposite signed polarizations, such patterning of the deposition is not observed for gold, for a wide range of concentrations studied (2E−8 to 1E−3M).

  10. Particle deposition in low-speed, high-turbulence flows

    DEFF Research Database (Denmark)

    Reck, Mads; Larsen, Poul Scheel; Ullum, U.

    2002-01-01

    The experimental and numerical study considers the concentration of airborne particulate contaminants, such as spores of spoilage fungi, and their deposition on a surface, in a petri dish, and on a warm box-shaped product placed in a food-processing environment. Field measurements by standard...... field measurements. Particle deposition is shown to be associated with near-wall coherent structures. Flow reversal, simulated by impulsive start, is shown to give higher deposition rates than steady mean flows. Key word index: Spoilage fungi; spores; food processing plant; deposition flux; large eddy...

  11. Particle size distribution of fly ash from co-incineration of bituminous coal with municipal solid waste

    Directory of Open Access Journals (Sweden)

    Cieślik Ewelina

    2018-01-01

    Full Text Available One of the source of air pollutants is emission from local coal-fired boiler-houses and domestic heating boilers. The consequence of incineration of municipal waste is the introduction of additional pollutants into the atmosphere, including fly ash. The aim of this work was to evaluate the particle size distribution of fly ash emitted by coal combustion and co-incineration of coal with municipal waste in a domestic 18 kW central heating boiler equipped with an automatic fuel feeder. Mixtures of bituminous coal with different types of solid waste (5, 10 and 15% of mass fraction were used. Solid waste types consisted of: printed, colored PE caps, fragmented cable trunking, fragmented car gaskets and shredded tires from trucks. During the incineration of a given mixture of municipal waste with bituminous coal, the velocity of exhaust gas was specified, the concentration and mass flow of fly ash were determined together with the physico-chemical parameters of the exhaust gas, the samples of emitted fly ash were taken as the test material. Particle size analysis of fly ash was performed using laser particle sizer Fritch Analysette 22. The PM10 share from all fly ashes from incineration of mixtures was about 100%. Differences were noted between PM2.5 and PM1.

  12. Particle size distribution of fly ash from co-incineration of bituminous coal with municipal solid waste

    Science.gov (United States)

    Cieślik, Ewelina; Konieczny, Tomasz; Bobik, Bartłomiej

    2018-01-01

    One of the source of air pollutants is emission from local coal-fired boiler-houses and domestic heating boilers. The consequence of incineration of municipal waste is the introduction of additional pollutants into the atmosphere, including fly ash. The aim of this work was to evaluate the particle size distribution of fly ash emitted by coal combustion and co-incineration of coal with municipal waste in a domestic 18 kW central heating boiler equipped with an automatic fuel feeder. Mixtures of bituminous coal with different types of solid waste (5, 10 and 15% of mass fraction) were used. Solid waste types consisted of: printed, colored PE caps, fragmented cable trunking, fragmented car gaskets and shredded tires from trucks. During the incineration of a given mixture of municipal waste with bituminous coal, the velocity of exhaust gas was specified, the concentration and mass flow of fly ash were determined together with the physico-chemical parameters of the exhaust gas, the samples of emitted fly ash were taken as the test material. Particle size analysis of fly ash was performed using laser particle sizer Fritch Analysette 22. The PM10 share from all fly ashes from incineration of mixtures was about 100%. Differences were noted between PM2.5 and PM1.

  13. Environmental impact of early Basque mining and smelting recorded in a high ash minerogenic peat deposit

    International Nuclear Information System (INIS)

    Monna, F.; Galop, D.; Carozza, L.; Tual, M.; Beyrie, A.; Marembert, F.; Chateau, C.; Dominik, J.; Grousset, F.E.

    2004-01-01

    More than four metres of core, covering almost 5000 years of deposition, were collected in a high ash minerogenic peat deposit located in the High Aldudes valley (Basque country), an area well known for its mineral abundance, exploited from Roman Times at least. Although minerogenic peatlands are not generally considered as the best archives to reconstruct past atmospheric metal deposition history, lead isotopic geochemistry demonstrates the integrity of the Pb record at least within the three upper meters; that is to say over the last four millennia. Zn, Cd and Cu may have been widely redistributed either by biological cycling, advective groundwater movements, or diffusional processes. Anthropogenic lead input phases are clearly pinpointed by positive shifts in Pb/Sc ratios with concomitant sharp drops in 206 Pb/ 207 Pb ratios. They are often accompanied by significant declines in tree taxa, interpreted as increasing demand for wood to supply energy for local mining and/or metallurgical operations. Periods of mining and/or smelting activity are identified during Antiquity and Modern Times, and are also confirmed by textual and field evidence. Inputs from the Rio Tinto (Southern Spain), often invoked as a major lead contributor to the European atmosphere during Roman Times, were not detected here. This remote source was probably masked by local inputs. Other mining and/or smelting phases, only suspected by archaeologists, are here identified as early as the Bronze Age. Although the durations of these phases are possibly overestimated because of detrital inputs consequent to the release of lead from polluted soils over a long period of time after major pollutant inputs, the periods at which pollution peaks occur are in good agreement with archaeological knowledge and palaeo-botanical data. The combination of geochemical and palaeo-botanical techniques with field archaeology, therefore provides a powerful tool in studying the interaction of early human societies with

  14. Anti-oxidative and inflammatory responses induced by fly ash particles and carbon black in lung epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Diabate, Silvia; Plaumann, Diana; Uebel, Caroline; Weiss, Carsten [Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Eggenstein-Leopoldshafen (Germany); Bergfeldt, Britta [Karlsruhe Institute of Technology, Institute of Technical Chemistry, Eggenstein-Leopoldshafen (Germany)

    2011-12-15

    Combustion-derived nanoparticles as constituents of ambient particulate matter have been shown to induce adverse health effects due to inhalation. However, the components inducing these effects as well as the biological mechanisms are still not fully understood. The fine fraction of fly ash particles collected from the electrostatic precipitator of a municipal solid waste incinerator was taken as an example for real particles with complex composition released into the atmosphere to study the mechanism of early biological responses of BEAS-2B human lung epithelial cells. The studies include the effects of the water-soluble and -insoluble fractions of the fly ash and the well-studied carbon black nanoparticles were used as a reference. Fly ash induced reactive oxygen species (ROS) and increased the total cellular glutathione (tGSH) content. Carbon black also induced ROS generation; however, in contrast to the fly ash, it decreased the intracellular tGSH. The fly ash-induced oxidative stress was correlated with induction of the anti-oxidant enzyme heme oxygenase-1 and increase of the redox-sensitive transcription factor Nrf2. Carbon black was not able to induce HO-1. ROS generation, tGSH increase and HO-1 induction were only induced by the insoluble fraction of the fly ash, not by the water-soluble fraction. ROS generation and HO-1 induction were markedly inhibited by pre-incubation of the cells with the anti-oxidant N-acetyl cysteine which confirmed the involvement of oxidative stress. Both effects were also reduced by the metal chelator deferoxamine indicating a contribution of bioavailable transition metals. In summary, both fly ash and carbon black induce ROS but only fly ash induced an increase of intracellular tGSH and HO-1 production. Bioavailable transition metals in the solid water-insoluble matrix of the fly ash mostly contribute to the effects. (orig.)

  15. Investigation of flow behaviour of coat/ash particles in an advanced pressurised fluidized bed gasifier (APFBG) using radiotracer technique

    International Nuclear Information System (INIS)

    Pant, H.J.; Sharma, V.K.; Gursharan Singh; Vidhya Kamadu, M.; Prakash, S.G.; Krishanamoorthy, S.; Ramani, N.V.S.; Sonde, R.R.

    2004-01-01

    Knowledge of Residence Time Distribution (RTD), Mean Residence Time (MRT) and degree of backmixing of solid phase is important for efficient operation of the coal gasifier. Radiotracer technique was used for measure RTD of coal/ash particles in a pilot-scale gasifier and obtain the values of MRT and backmixing. Lanthanum 140 labeled coal (100 g) was used as a tracer. The tracer was instantaneously injected into the coal feed line and monitored at ash and gas outlets of the gasifier using collimated scintillation detectors. The measured RTD data were treated and MRTs of coal/ash particles were determined. The treated data were simulated using tank-in-series model. The simulation RTD data indicated good degree of mixing with minor bypassing/short-circulating of coal particles. The results of the investigation were found useful for scale-up of the gasification process. (author)

  16. Mathematical modelling of water and gas transport in layered soil covers for coal ash deposit

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, M [Kemakta Consultants Co, Stockholm (SE); Rasmuson, A [Chalmers University of Technology, Goeteborg (SE). Dept. of Chemical Engineering Design

    1991-06-19

    In phase 1 of this study the design of soil covers for deposits of coal ash from energy production was studied with regard to various parameters like: climate, cover slope, hydraulic conductivity of tight layer and length of cover. One of the main results was the relatively large risk for total saturation up to the surface and overflow which may cause surface erosion problems. In the present study two theoretical cases are studied to further elucidate the problem. A case from the phase 1 study is used to illustrate the effect of increased infiltration. Calculations show that total saturation and thereby overflow is achieved when the infiltration is increased by 20% in March, but not when increased by 10% only. This shows that the margin in an acceptable case may be small. A cover treated in phase 1, where totally saturated conditions were obtained, was modified so that two decimeters of the one meter till in its bottom part were exchanged for a drainage layer. It is shown that the effect of this layer is large. A negative side-effect, however, is that gas flow may increase due to the lower saturation of the cover. Calculations were made for a real soil covered mine tailings deposit at Bersbo. This deposit was chosen mainly because it is the only well documented case in Sweden where soil covers are used for securing a deposit, but also because some contradictory results as compared to theory were obtained. Another topic studied in the present work was the influence of a heterogeneous clay layer. For example, a weak zone with a hydraulic conductivity of 10{sup -7} m/s (10{sup -9} m/s for the rest of the clay), covering 0.5 m x 0.5 m of 10 m in length and 5 m in width, will increase the flow through the bottom of the cover with almost 30%. The gas transport through the heterogeneous soil cover was also studied, showing about 5 times increased gas transport rate around the weak zone, but almost no difference about 1 m from the weak zone. (29 figs., 5 tabs., 27 refs.).

  17. Alpha-particle confinement and helium ash accumulation in stellarator reactors

    International Nuclear Information System (INIS)

    Ho, D.D.-M.; Kulsrud, R.M.

    1986-01-01

    The effect of local magnetic wells produced by the external helical windings of a stellarator reactor on α-particle confinement is investigated by using the Fokker-Planck equation. It is found that α-particles can deposit most of their energy into the background plasma before they scatter into the trapped region in velocity space and are lost. An estimate is made on the steady-state, low energy (thermal) α-particle concentration. The result shows that this concentration will be less than a few per cent of the background plasma density. (author)

  18. Deposition of Aerosol Particles in Electrically Charged Membrane Filters

    Energy Technology Data Exchange (ETDEWEB)

    Stroem, L

    1972-05-15

    A theory for the influence of electric charge on particle deposition on the surface of charged filters has been developed. It has been tested experimentally on ordinary membrane filters and Nuclepore filters of 8 mum pore size, with a bipolar monodisperse test aerosol of 1 mum particle diameter, and at a filter charge up to 20 muC/m2. Agreement with theory was obtained for the Coulomb force between filter and particle for both kinds of filters. The image force between charged filter and neutral particles did not result in the predicted deposition in the ordinary membrane filter, probably due to lacking correspondence between the filter model employed for the theory, and the real filter. For the Nuclepore filter a satisfactory agreement with theory was obtained, also at image interaction

  19. High resolution 3D confocal microscope imaging of volcanic ash particles.

    Science.gov (United States)

    Wertheim, David; Gillmore, Gavin; Gill, Ian; Petford, Nick

    2017-07-15

    We present initial results from a novel high resolution confocal microscopy study of the 3D surface structure of volcanic ash particles from two recent explosive basaltic eruptions, Eyjafjallajökull (2010) and Grimsvötn (2011), in Iceland. The majority of particles imaged are less than 100μm in size and include PM 10 s, known to be harmful to humans if inhaled. Previous studies have mainly used 2D microscopy to examine volcanic particles. The aim of this study was to test the potential of 3D laser scanning confocal microscopy as a reliable analysis tool for these materials and if so to what degree high resolution surface and volume data could be obtained that would further aid in their classification. First results obtained using an Olympus LEXT scanning confocal microscope with a ×50 and ×100 objective lens are highly encouraging. They reveal a range of discrete particle types characterised by sharp or concave edges consistent with explosive formation and sudden rupture of magma. Initial surface area/volume ratios are given that may prove useful in subsequent modelling of damage to aircraft engines and human tissue where inhalation has occurred. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Quantitative trace element analysis of individual fly ash particles by means of X-ray microfluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Vincze, L.; Somogyi, A.; Osan, J.; Vekemans, B.; Torok, S.; Janssens, K.; Adams, F. [Universitaire of Instelling Antwerp, Wilrijk (Belgium). Dept. of Chemistry

    2002-07-01

    A new quantification procedure was developed for the evaluation of X-ray microfluorescence (XRF) data sets obtained from individual particles, based on iterative Monte Carlo (MC) simulation. Combined with the high sensitivity of synchrotron radiation-induced XRF spectroscopy, the method was used to obtain quantitative information down to trace-level concentrations from micrometer-sized particulate matter. The detailed XRF simulation model was validated by comparison of calculated and experimental XRF spectra obtained for glass microsphere standards, resulting in uncertainties in the range of 3-10% for the calculated elemental sensitivities. The simulation model was applied for the quantitative analysis of X-ray tube and synchrotron radiation-induced scanning micro-XRF spectra of individual coal and wood fly ash particles originating from different Hungarian power plants. By measuring the same particles by both methods the major, minor, and trace element compositions of the particles were determined. The uncertainty of the MC based quantitative analysis scheme is estimated to be in the range of 5-30%.

  1. Time-fractional particle deposition in porous media

    Science.gov (United States)

    Xu, Jianping

    2017-05-01

    In the percolation process where fluids carry small solid particles, particle deposition causes a real-time permeability change of the medium as the swarm of particles propagates along the medium. Then the permeability change influences percolation and deposition behaviors as a feedback. This fact triggers memory effect in the deposition dynamics, which means the particulate transport and deposition behaviors become history-dependent. In this paper, we conduct the time-fractional generalization of the classical phenomenological model of particle deposition in porous media to incorporate the memory effect. We tested and compared the effects of employing different types of fractional operators, i.e. the Riemann-Liouville type, the Hadamard type and the Prabhakar type. Numerical simulation results show that the system behaviors vary according to the change of distinct memory kernels in an expected way. We then discuss the physical meaning of the time-fractional generalization. It is shown that different types of fractional operators unanimously ground themselves on the local-Newtonian time transformation in a complex system, which is equivalent to a class of history integrals. By the introduction of various memory kernels, it enables the model to more powerfully fit and approximate observed data. Further, the fundamental meaning of this work is not to show which fractional operator is ‘better’, but to argue collectively the legitimacy and practicality of a non-Markovian particle deposition dynamics in porous media, and in fact it is admissible to a bunch of memory kernels which differ greatly from each other in functional forms. Hopefully the presented generalized mass conservation formalism offers a broader framework to investigate transport problems in porous media.

  2. Time-fractional particle deposition in porous media

    International Nuclear Information System (INIS)

    Xu, Jianping

    2017-01-01

    In the percolation process where fluids carry small solid particles, particle deposition causes a real-time permeability change of the medium as the swarm of particles propagates along the medium. Then the permeability change influences percolation and deposition behaviors as a feedback. This fact triggers memory effect in the deposition dynamics, which means the particulate transport and deposition behaviors become history-dependent. In this paper, we conduct the time-fractional generalization of the classical phenomenological model of particle deposition in porous media to incorporate the memory effect. We tested and compared the effects of employing different types of fractional operators, i.e. the Riemann–Liouville type, the Hadamard type and the Prabhakar type. Numerical simulation results show that the system behaviors vary according to the change of distinct memory kernels in an expected way. We then discuss the physical meaning of the time-fractional generalization. It is shown that different types of fractional operators unanimously ground themselves on the local-Newtonian time transformation in a complex system, which is equivalent to a class of history integrals. By the introduction of various memory kernels, it enables the model to more powerfully fit and approximate observed data. Further, the fundamental meaning of this work is not to show which fractional operator is ‘better’, but to argue collectively the legitimacy and practicality of a non-Markovian particle deposition dynamics in porous media, and in fact it is admissible to a bunch of memory kernels which differ greatly from each other in functional forms. Hopefully the presented generalized mass conservation formalism offers a broader framework to investigate transport problems in porous media. (paper)

  3. Fate and effect of tire rubber ash nano-particles (RANPs) in cucumber.

    Science.gov (United States)

    Moghaddasi, Sahar; Hossein Khoshgoftarmanesh, Amir; Karimzadeh, Fatholah; Chaney, Rufus

    2015-05-01

    There are growing interests on effects of nano-materials on living organisms including higher plants. No report is available on positive and negative effects of rubber ash nano-particles (RANPs) on edible plants. Recently, we reported the possibility of using waste tire rubber and rubber ash as zinc (Zn) fertilizer for plants. In this nutrient solution culture study, for the first time, root uptake and the effects of RANPs on growth and Zn, cadmium (Cd), and lead (Pb) concentration in cucumber was investigated. Various Zn levels (0, 1, 5, 25, 125mgL(-1)) were applied in the form of RANPs or ZnSO4. The root RANPs uptake was visualized by light (LA), scanning electron (SEM), and transmission electron microcopies (TEM). At all Zn levels, cucumber plants supplied with RANPs produced higher shoot and root biomass compared with those supplied with ZnSO4. In addition, the RANPs resulted in higher accumulation of Zn in cucumber tissues in comparison with ZnSO4; although phytotoxicity of Zn from ZnSO4 was greater than that from RANPs. Clear evidence of the RANPs penetration into the root cells was obtained by using SEM and TEM. Filaments of RANPs were also observed at the end of roots by LM and TEM. Further research is needed to clarify the fate of the RANPs in plant cells and their possible risks for food chain. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Prevention of the ash deposits by means of process conditions in biomass gasification; Biomassapolttoaineiden tuhkan kuonaantumiskaeyttaeytymisen estaeminen prosessiolosuhteiden avulla

    Energy Technology Data Exchange (ETDEWEB)

    Moilanen, A; Laatikainen-Luntama, J; Nieminen, M; Kurkela, E; Korhonen, J [VTT Energy, Espoo (Finland)

    1997-10-01

    In fluidised-bed gasification, various types of deposits and agglomerates may be formed by biomass ash in the bed, in upper zones of the reactor, for instance in cyclones. These may decisively hamper the operation of the process. The aim of the project was to obtain data on the detrimental fouling behaviour of the ash of different types of biomass in fluidised-bed gasification, and on the basis of these data to determine the process conditions and ways of preventing this kind of behaviour. Different types of biomass fuel relevant to energy production such as straw, wood residue were be used as samples. The project consisted of laboratory studies and fluidised-bed reactor tests including ash behaviour studied both in the bed and freeboard. In laboratory tests, the sample material was characterised as a function of different process parameters. In fluid-bed reactors, the most harmful biomasses were tested using process variables such as temperature, bed material and the gasification agents. Bubbling fluidised-bed gasification tests with wheat straw showed that agglomerates with different sizes and structures formed in the bed depending on the temperature, the feed gas composition and bed material. Agglomerates consisted of molten ash which sintered with bed material and other solids. In all BFB tests, freeboard walls were slicked by ash agglomerates (different amounts) which, however, were easily removable. The results of this project and the earlier pilot-scale gasification experience obtained with the same feedstocks showed that useful characteristic data about ash behaviour can be obtained using laboratory tests and small scale reactors. (orig.)

  5. A simple semi-empirical approach to model thickness of ash-deposits for different eruption scenarios

    Directory of Open Access Journals (Sweden)

    A. O. González-Mellado

    2010-11-01

    Full Text Available The impact of ash-fall on people, buildings, crops, water resources, and infrastructure depends on several factors such as the thickness of the deposits, grain size distribution and others. Preparedness against tephra falls over large regions around an active volcano requires an understanding of all processes controlling those factors, and a working model capable of predicting at least some of them. However, the complexity of tephra dispersion and sedimentation makes the search of an integral solution an almost unapproachable problem in the absence of highly efficient computing facilities due to the large number of equations and unknown parameters that control the process. An alternative attempt is made here to address the problem of modeling the thickness of ash deposits as a primary impact factor that can be easily communicated to the public and decision-makers. We develop a semi-empirical inversion model to estimate the thickness of non-compacted deposits produced by an explosive eruption around a volcano in the distance range 4–150 km from the eruptive source.

    The model was elaborated from the analysis of the geometric distribution of deposit thickness of 14 world-wide well-documented eruptions. The model was initially developed to depict deposits of potential eruptions of Popocatépetl and Colima volcanoes in México, but it can be applied to any volcano. It has been designed to provide planners and Civil Protection authorities of an accurate perception of the ash-fall deposit thickness that may be expected for different eruption scenarios. The model needs to be fed with a few easy-to-obtain parameters, namely, height of the eruptive column, duration of the explosive phase, and wind speed and direction, and its simplicity allows it to run in any platform, including a personal computers and even a notebook. The results may be represented as tables, two dimensional thickness-distance plots, or isopach maps using any available

  6. Appendices 1-3 - the effects of combustion on ash and deposits from low rank coals

    Energy Technology Data Exchange (ETDEWEB)

    Ledger, R.C.; Ottrey, A.L.; Mackay, G.H.

    1985-12-01

    Thermomechanical analyses (TMA) of ashes derived from combustion of fourteen coal samples from Victorian and South Australian coalfields are presented in the results volumes of this report (Volume 2-4). This appendix describes the analytical equipment used, the modifications that were incorporated and the technique developed for analysis and interpretation of the data. To aid identification, limited numbers of analyses were performed on reference materials, the results of which are presented in this appendix. Analyses were performed on a modified Stanton Redcroft 790 series thermomechanical analyser. The aim was to identify components in the ashes and to gain an understanding of the sintering and fusion behaviour of the ashes up to temperatures encountered in large scale boilers. As part of the main project, ashes were also submitted to simultaneous Differential Thermal Analysis and Thermogravimetry (DTA-TG). For each coal burnt in this investigation the Test Bank 1 and precipitator ashes produced at a flame temperature of 1200/sup o/C and 3% excess oxygen were examined by TMA, as were ashes from tests at other flame temperatures and at 3% excess oxygen for four of the coals. This was to investigate the effects of variation in combustion conditions on ash properties. The results are presented in Volume 2-4 of this report as tables, giving details of events and assignments and as a formalised TMA pattern for each ash tested.

  7. Modeling Dry Deposition of Aerosol Particles on Rough Surfaces

    Czech Academy of Sciences Publication Activity Database

    Hussein, T.; Smolík, Jiří; Kerminen, V.-M.; Kulmala, M.

    2012-01-01

    Roč. 46, č. 1 (2012), s. 44-59 ISSN 0278-6826 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosol particles * dry deposition * transport Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.780, year: 2012

  8. Spatial distribution of volcanic ash deposits of 2011 Puyehue-Cordón Caulle eruption in Patagonia as measured by a perturbation in NDVI temporal dynamics

    Science.gov (United States)

    Easdale, M. H.; Bruzzone, O.

    2018-03-01

    Volcanic ash fallout is a recurrent environmental disturbance in forests, arid and semi-arid rangelands of Patagonia, South America. The ash deposits over large areas are responsible for several impacts on ecological processes, agricultural production and health of local communities. Public policy decision making needs monitoring information of the affected areas by ash fallout, in order to better orient social, economic and productive aids. The aim of this study was to analyze the spatial distribution of volcanic ash deposits from the eruption of Puyehue-Cordón Caulle in 2011, by identifying a sudden change in the Normalized Difference Vegetation Index (NDVI) temporal dynamics, defined as a perturbation located in the time series. We applied a sparse-wavelet transform using the Basis Pursuit algorithm to NDVI time series obtained from the Moderate Resolution Image Spectroradiometer (MODIS) sensor, to identify perturbations at a pixel level. The spatial distribution of the perturbation promoted by ash deposits in Patagonia was successfully identified and characterized by means of a perturbation in NDVI temporal dynamics. Results are encouraging for the future development of a new platform, in combination with data from forecasting models and tracking of ash cloud trajectories and dispersion, to inform stakeholders to mitigate impact of volcanic ash on agricultural production and to orient public intervention strategies after a volcanic eruption followed by ash fallout over a wide region.

  9. Deposition of magnetite particles onto alloy-800 steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Basset, M.; Arbeau, N.; McInerney, J.; Lister, D.H. [Univ. of New Brunswick, Dept. of Chemical Engineering, Fredericton, NB (Canada)

    1998-07-01

    Fouling is a particularly serious problem in the power generating industry. Deposits modify the thermalhydraulic characteristics of heat transfer surfaces by changing the resistance to heat transfer and the resistance to fluid flow, and, if thick enough, can harbour aggressive chemicals. Deposits are also implicated in the increase of radiation fields around working areas in the primary heat transfer systems of nuclear power plants. In order to understand the preliminary steps of the formation of corrosion product deposits on the outsides of steam generator tubes, a laboratory program has investigated the deposition of magnetite particles from suspension in water onto Alloy-800 surfaces under various conditions of flow, chemistry and boiling heat transfer. A recirculating loop made of stainless steel operating at less than 400kPa pressure, with a nominal coolant temperature of 90 degrees C, was equipped with a vertical glass column which housed a 2.5E-01m-long Alloy-800 boiler tube capable of generating a heat flux of 240kW/m{sup 2} . A concentration of suspended magnetite of 5.0E-03kg/m{sup 3} was maintained in the recirculating coolant, which was maintained at a pH of 7.5. The magnetite was synthesized with a sol-gel process, which was developed to produce reproducibly monodispersed, colloidal (<1{mu}m) and nearly spherical particles. A radiotracing method was used to characterize the deposit evolution with time and to quantify the removal of magnetite particles. The results from a series of deposition experiments are presented here. The deposition process is described in terms of a two-step mechanism: the transport step, involving the transport from the bulk of the liquid to the vicinity of the surface, followed by the attachment step, involving the attachment of the particle onto the surface. Under non-boiling heat transfer conditions, diffusion seems to be the dominant factor ruling deposition with a small contribution from thermophoresis; removal was

  10. Deposition of magnetite particles onto alloy-800 steam generator tubes

    International Nuclear Information System (INIS)

    Basset, M.; Arbeau, N.; McInerney, J.; Lister, D.H.

    1998-01-01

    Fouling is a particularly serious problem in the power generating industry. Deposits modify the thermalhydraulic characteristics of heat transfer surfaces by changing the resistance to heat transfer and the resistance to fluid flow, and, if thick enough, can harbour aggressive chemicals. Deposits are also implicated in the increase of radiation fields around working areas in the primary heat transfer systems of nuclear power plants. In order to understand the preliminary steps of the formation of corrosion product deposits on the outsides of steam generator tubes, a laboratory program has investigated the deposition of magnetite particles from suspension in water onto Alloy-800 surfaces under various conditions of flow, chemistry and boiling heat transfer. A recirculating loop made of stainless steel operating at less than 400kPa pressure, with a nominal coolant temperature of 90 degrees C, was equipped with a vertical glass column which housed a 2.5E-01m-long Alloy-800 boiler tube capable of generating a heat flux of 240kW/m 2 . A concentration of suspended magnetite of 5.0E-03kg/m 3 was maintained in the recirculating coolant, which was maintained at a pH of 7.5. The magnetite was synthesized with a sol-gel process, which was developed to produce reproducibly monodispersed, colloidal (<1μm) and nearly spherical particles. A radiotracing method was used to characterize the deposit evolution with time and to quantify the removal of magnetite particles. The results from a series of deposition experiments are presented here. The deposition process is described in terms of a two-step mechanism: the transport step, involving the transport from the bulk of the liquid to the vicinity of the surface, followed by the attachment step, involving the attachment of the particle onto the surface. Under non-boiling heat transfer conditions, diffusion seems to be the dominant factor ruling deposition with a small contribution from thermophoresis; removal was considered

  11. The potential of four woody species for the revegetation of fly ash deposits from the ‘Nikola Tesla-a’ thermoelectric plant (Obrenovac, Serbia

    Directory of Open Access Journals (Sweden)

    Kostić Olga

    2012-01-01

    Full Text Available Four woody species, Tamarix tentandra Pallas, Populus alba L. and Robinia pseudoacacia L. (planted and Amorpha fruticosa L. (naturally colonized were studied at two fly ash deposit lagoons, weathered 3 (L1 and 11 years (L2. All species were assessed in terms of their invasive ability, photosynthetic efficiency, photosynthetic pigments and damage symptoms, while the characteristics of the habitat were assessed in terms of trace element content and the pH and EC of the ash. A reduced vitality of all populations growing on the ash was observed, except for the naturally colonized A. fruticosa. High vitality on all sites, except at L2, increased chlorophyll content and absence of damage symptoms indicates a tolerance in relation to the uptake of toxic elements from the ash. Therefore, the characteristics of naturally colonized species can be used for modeling future actions of biological restoration of fly ash deposits.

  12. Experimental study on the particles deposition in the sampling duct

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Charuau, J. [Institut de Protection et de Surete Nucleaire, Yvette (France)

    1995-02-01

    A high standard of protection against the harmful effects of radioactive aerosol dissemination requires a measurement, as representative as possible, of their concentration. This measurement depends on the techniques used for aerosol sampling and transfer to the detector, as well as on the location of the latter with respect to the potential sources. The aeraulic design of the apparatus is also an important factor. Once collected the aerosol particles often have to travel through a variably shaped duct to the measurement apparatus. This transport is responsible for losses due to the particles deposition on the walls, leading to a distortion on the concentration measurements and a change in the particle size distribution. To estimate and minimize measurement errors it is important to determine the optimal transport conditions when designing a duct; its diameter and material, the radius of curvature of the bends and the flow conditions must be defined in particular. This paper presents an experimental study in order to determine, for each deposition mechanism, the retained fraction, or the deposition velocity for different flow regimes. This study has pointed out that it exists a favourable flow regime for the particle transport through the sampling ducts (2 500 < Re < 5 000). It has been established, for any particle diameters, equations to predict the aerosol penetration in smooth-walled cylindrical metal ducts.

  13. Theory and practice of corrosion related to ashes and deposits in a WtE boiler.

    Science.gov (United States)

    Verbinnen, Bram; De Greef, Johan; Van Caneghem, Jo

    2018-03-01

    Corrosion of heat-exchanging components is one of the main operational problems in Waste-to-Energy plants, limiting the electrical efficiency that can be reached. Corrosion is mainly related to the devolatilization and/or formation of chlorides, sulphates and mixtures thereof on the heat-exchanging surfaces. Theoretical considerations on this corrosion were already put forward in literature, but this paper now for the first time combines theory with a large scale sampling campaign of several Waste-to-Energy plants. Based on the outcome of elemental and mineralogical analysis, the distribution of Cl and S in ashes sampled throughout the plant during normal operation is explained. Cl concentrations are high (15-20%) in the first empty pass, decrease in the second and third empty pass, but increase again in the convective part, whereas the S concentrations show an inverse behavior, with the highest concentrations (30%) observed in the second and third empty pass. Sampling of deposits on specific places where corrosion possibly occurred, gives a better insight in the mechanisms related to corrosion phenomena in real-scale WtE plants and provides practical evidence for some phenomena that were only assumed on the basis of theory or lab scale experiments before. More specific, it confirms the role of oxygen content, temperatures in the different stages of the boiler, the presence of polysulphates, Pb and Zb, and the concentrations of HCl and SO 2 in the flue gas for different types of boiler corrosion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Particle dispersion at road building using fly ash - model review, investigation of influence of humidity content for dust emission and fly ash particle characterisation; Partikelspriding vid byggnation av vaeg med aska - modelloeversikt, undersoekning av fuktighetsgradens betydelse foer damning och karaktaerisering av partiklar fraan flygaska

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Mats; Wik, Ola; Frogner-Kockum, Paul

    2009-03-15

    Ashes from incineration may have very good properties, such as building materials in roads. This use assumes that the ashes do not have serious environmental and health effects. Since ash might generate large amounts of dust in handling the issue on the extent of dusting and dust properties has proved to be important to assess the risks of environmental impacts during use. Inhalable particles in the ambient air are a problem that has attracted much attention and is regarded as one of the most serious health related air pollutants. The present project has aimed to: describe appropriate models for calculating the emission and dispersion of dust in the air during the construction of ash containing roads, evaluate a new method to examine the importance of moisture for dusting from fly ash and investigate the properties of fly ash, making it possible to identify ash in samples of airborne particles. The target audience is ash manufacturers, contractors and consultants with a need for knowledge of ash dusting. Project modules have included: a literature review to identify appropriate modelling tools to describe the emission and dispersion of dust from road building with ash a method study in which a piece of equipment called Duster, have been evaluated for assessing the significance of the ash humidity to dusting, and an electron microscope study where morphology and composition of some ashes, cement and Merit have been studied to find ways to identify ash particles in dust samples. The results show that there is a lack of overall model tools that can describe the emissions from all the management operations of ashes at road building and that existing models sometimes lack key variables. Also, because of high silt content of ashes, some models are deemed inferior compared to when used for ordinary mineral material. Furthermore, attempts with the Duster shows that the method works, but with limited precision, and that dusting from the ash samples was reduced significantly

  15. Volcanic ash deposition, eelgrass beds, and inshore habitat loss from the 1920s to the 1990s at Chignik, Alaska

    Science.gov (United States)

    Zimmermann, Mark; Ruggerone, Gregory T.; Freymueller, Jeffrey T.; Kinsman, Nicole; Ward, David H.; Hogrefe, Kyle R.

    2018-03-01

    We quantified the shallowing of the seafloor in five of six bays examined in the Chignik region of the Alaska Peninsula, confirming National Ocean Service observations that 1990s hydrographic surveys were shallower than previous surveys from the 1920s. Castle Bay, Chignik Lagoon, Hook Bay, Kujulik Bay and Mud Bay lost volume as calculated from Mean Lower Low Water (Chart Datum) to the deepest depths and four of these sites lost volume from Mean High Water to the deepest depths. Calculations relative to each datum were made because tidal datum records exhibited an increase in tidal range in this region from the 1920s to the 1990s. Our analysis showed that Mud Bay is quickly disappearing while Chignik Lagoon is being reduced to narrow channels. Anchorage Bay was the only site that increased in depth over time, perhaps due to erosion. Volcanoes dominate the landscape of the Chignik area. They have blanketed the region in deep ash deposits before the time frame of this study, and some have had smaller ash-producing eruptions during the time frame of this study. Remobilization of land-deposited ash and redeposition in marine areas - in some locations facilitated by extensive eelgrass (Zostera marina) beds (covering 54% of Chignik Lagoon and 68% of Mud Bay in 2010) - is the most likely cause of shallowing in the marine environment. Loss of shallow water marine habitat may alter future abundance and distribution of several fish, invertebrate and avian species.

  16. Engineering Particle Surface Chemistry and Electrochemistry with Atomic Layer Deposition

    Science.gov (United States)

    Jackson, David Hyman Kentaro

    Atomic layer deposition (ALD) is a vapor phase thin film coating technique that relies on sequential pulsing of precursors that undergo self-limited surface reactions. The self- limiting reactions and gas phase diffusion of the precursors together enable the conformal coating of microstructured particles with a high degree of thickness and compositional control. ALD may be used to deposit thin films that introduce new functionalities to a particle surface. Examples of new functionalities include: chemical reactivity, a mechanically strong protective coating, and an electrically resistive layer. The coatings properties are often dependent on the bulk properties and microstructure of the particle substrate, though they usually do not affect its bulk properties or microstructure. Particle ALD finds utility in the ability to synthesize well controlled, model systems, though it is expensive due to the need for costly metal precursors that are dangerous and require special handling. Enhanced properties due to ALD coating of particles in various applications are frequently described empirically, while the details of their enhancement mechanisms often remain the focus of ongoing research in the field. This study covers the various types of particle ALD and attempts to describe them from the unifying perspective of surface science.

  17. Theoretical calculation of solid particles deposition from the air

    Directory of Open Access Journals (Sweden)

    Bobro Milan

    2002-03-01

    Full Text Available This paper presents the calculation of harmful substance deposition (air pollution from the point source (Slanèo, et al., 2001 using equation (1. The point source shall be understood as e.g. chimneys of factory, heat plant, incinerator, boiler plant, local heating plant, etc.The theoretical calculation of concentration (1, or deposition (8 is based on the study of transfer and dispersion of pollution in air (Slanèo, et al., 2000a. The movement of pollution in air consists of a movement of the air itself and a relative movement of pollution particles and air, while the movement of harmful substance in the smoke trail is under the influence of turbulent diffusion, convection and gravitation. Molecular diffusion is not important in this process. When calculating concentrations (1 and deposition (8 of air pollution on a particular place near the source, it is assumed that the air speed is constant, the direction of wind does not change with the height and the source of air pollution is time-constant. The change in the wind speed with the height depends on the stability class of atmosphere (temperature gradient (Slanèo, et al., 2000a and it is calculated using equation (10.The theoretical calculation of concentration and or deposition of harmful substance from the point source (1 and (8 shall be applied if the harmful substance particles, which leave the source, have the same density (composition, shape (spherical and size.The experimental observations of dust deposition showed the significance of 0.1-20 µm particles. The application of equation (1 to calculate the concentration is conditioned, in addition to the recognition of source parameters and meteorological conditions, by the recognition of the particle sedimentation speed, which changes with the size of particle radius (2.For a practical calculation of deposition it is therefore necessary to know the differential distribution function f(r of particle radii, which can be made on the basis

  18. Individual particles of cryoconite deposited on the mountain glaciers of the Tibetan Plateau: Insights into chemical composition and sources

    Science.gov (United States)

    Dong, Zhiwen; Qin, Dahe; Kang, Shichang; Liu, Yajun; Li, Yang; Huang, Jie; Qin, Xiang

    2016-08-01

    Cryoconite deposited on mountain glacier surfaces is significant for understanding regional atmospheric environments, which could influence the albedo and energy balance of the glacier basins, and maintain the glacial microbiology system. Field observations were conducted on the glaciers of western China, including Laohugou Glacier No.12 (LHG), Tanggula Dongkemadi Glacier (TGL), Zhadang Glacier (ZD), and Baishui Glacier No.1 in the Yulong Mountains (YL), as well as Urumqi Glacier No.1 in the Tianshan Mountains (TS) for comparison with locations in the Tibetan Plateau, in addition to laboratory TEM-EDX analysis of the individual cryoconite particles filtered on lacey carbon (LC) and calcium-coated carbon (Ca-C) TEM grids. This work provided information on the morphology and chemical composition, as well as a unique record of the particle's physical state, of cryoconite deposition on the Tibetan Plateau. The result showed that there is a large difference in the cryoconite particle composition between various locations on the Tibetan Plateau. In total, mineral dust particles were dominant (>50%) in the cryoconite at all locations. However, more anthropogenic particles (e.g., black carbon (BC) and fly ash) were found in YL (38%) and ZD (22%) in the Ca-C grids in the southern locations. In TGL, many NaCl and MCS particles (>10%), as well as few BC and biological particles (<5%), were found in cryoconite in addition to mineral dust. In TS, the cryoconite is composed primarily of mineral dust, as well as BC (<5%). Compared with other sites, the LHG cryoconite shows a more complex composition of atmospheric deposition with sufficient NaCl, BC, fly ash and biological particles (6% in LC grid). The higher ratio of anthropogenic particles in the southern Tibetan Plateau is likely caused by atmospheric pollutant transport from the south Asia to the Tibetan Plateau. Cryoconite in the northern locations (e.g., TGL, LHG, and TS) with higher dust and salt particle ratio are

  19. Chemical signature of two Permian volcanic ash deposits within a bentonite bed from Melo, Uruguay

    Directory of Open Access Journals (Sweden)

    Liane M. Calarge

    2006-09-01

    Full Text Available A Permian bentonite deposit at Melo, Uruguay is composed of a calcite-cemented sandstone containing clay pseudomorphs of glass shards (0-0.50 m overlying a pink massive clay deposit (0.50-2.10m. The massive bed is composed of two layers containing quartz and smectite or pure smectite respectively. The smectite is remarkably homogeneous throughout the profile: it is a complex mixed layer composed of three layer types whose expandability with ethylene glycol (2EG 1EG or 0EG sheets in the interlayer zone which correspond to low-, medium- and high-charge layers respectively varies with the cation saturating the interlayer zone. The smectite homogeneity through the profile is the signature of an early alteration process in a lagoonal water which was over saturated with respect to calcite. Compaction during burial has made the bentonite bed a K-depleted closed system in which diagenetic illitization was inhibited. Variations in major, REE and minor element abundances throughout the massive clay deposit suggest that it originated from two successive ash falls. The incompatible element abundances are consistent with that of a volcanic glass fractionated from a rhyolite magma formed in a subduction/collision geological context.Um depósito Permiano de bentonita em Melo, Uruguai,é composto por um arenito com cimento calcítico contendo pseudomorfos de argila sobre detritos vítreos(0-0.50 m superpostos a um deposito maciço de argila rosado (0.50-2.10 m. A camada maciça é composta por dois níveis contendo quartzo e esmectita ou esmectita pura, respectivamente. A homogeneidade de esmectita ao longo do perfil é notável: trata-se de um interestratificado composto de três tipos de camadas, cuja expansibilidade com etileno-glicol (folhas 2EG, 1EG ou 0EG na zona interfoliar correspondentes a camadas com baixa, média e alta carga, respectivamente variam com o tipo de cátion que satura a zona interfoliar. A homogeneidade da esmectita ao longo do perfil

  20. Depositing nanometer-sized particles of metals onto carbon allotropes

    Science.gov (United States)

    Watson, Kent A. (Inventor); Fallbach, Michael J. (Inventor); Ghose, Sayata (Inventor); Smith, Joseph G. (Inventor); Delozier, Donavon M. (Inventor); Connell, John W. (Inventor)

    2010-01-01

    A process for depositing nanometer-sized metal particles onto a substrate in the absence of aqueous solvents, organic solvents, and reducing agents, and without any required pre-treatment of the substrate, includes preparing an admixture of a metal compound and a substrate by dry mixing a chosen amount of the metal compound with a chosen amount of the substrate; and supplying energy to the admixture in an amount sufficient to deposit zero valance metal particles onto the substrate. This process gives rise to a number of deposited metallic particle sizes which may be controlled. The compositions prepared by this process are used to produce polymer composites by combining them with readily available commodity and engineering plastics. The polymer composites are used as coatings, or they are used to fabricate articles, such as free-standing films, fibers, fabrics, foams, molded and laminated articles, tubes, adhesives, and fiber reinforced articles. These articles are well-suited for many applications requiring thermal conductivity, electrical conductivity, antibacterial activity, catalytic activity, and combinations thereof.

  1. Characteristics of airflow and particle deposition in COPD current smokers

    Science.gov (United States)

    Zou, Chunrui; Choi, Jiwoong; Haghighi, Babak; Choi, Sanghun; Hoffman, Eric A.; Lin, Ching-Long

    2017-11-01

    A recent imaging-based cluster analysis of computed tomography (CT) lung images in a chronic obstructive pulmonary disease (COPD) cohort identified four clusters, viz. disease sub-populations. Cluster 1 had relatively normal airway structures; Cluster 2 had wall thickening; Cluster 3 exhibited decreased wall thickness and luminal narrowing; Cluster 4 had a significant decrease of luminal diameter and a significant reduction of lung deformation, thus having relatively low pulmonary functions. To better understand the characteristics of airflow and particle deposition in these clusters, we performed computational fluid and particle dynamics analyses on representative cluster patients and healthy controls using CT-based airway models and subject-specific 3D-1D coupled boundary conditions. The results show that particle deposition in central airways of cluster 4 patients was noticeably increased especially with increasing particle size despite reduced vital capacity as compared to other clusters and healthy controls. This may be attributable in part to significant airway constriction in cluster 4. This study demonstrates the potential application of cluster-guided CFD analysis in disease populations. NIH Grants U01HL114494 and S10-RR022421, and FDA Grant U01FD005837.

  2. Correlation and stratigraphic eruption age of the pyroclastic flow deposits and wide spread volcanic ashes intercalated in the Pliocene-Pleistocene strata, central Japan

    International Nuclear Information System (INIS)

    Nagahashi, Yoshitaka; Satoguchi, Yasufumi; Yoshikawa, Shusaku

    2000-01-01

    Three pyroclastic flow deposits in the Takayama and Omine area, central Honshu, are correlated to the distal widespread volcanic ashes intercalated in the Plio-Pleistocene boundary strata in central Japan. The correlation is based on these stratigraphic relationships, facies, magnetostratigraphy, petrographic properties such as mineral assemblage, refractive index and chemical composition of the volcanic glasses and orthopyroxene. As the result of these correlation, the eruption age of the proximal pyroclastic flow deposits have become clear. And precise correlation between proximal eruption units and distal depositional units is now possible. Ho-Kd 39 Tephra erupted at about 1.76 Ma, forming a co-ignimbrite ash, which deposited in the Kanto sedimentary basin. Eb-Fukuda Tephra erupted at about 1.75 Ma, and distal volcaniclastic deposit sedimented in the Kinki, Niigata and Kanto sedimentary basins. The eruptional and depositional phase are divided into the stage 1, stage 2 (early), stage 2 (late) and stage 3. Stage 1 is phreato-plinian type eruption phase, forming distal ash fall deposit. Stage 2 (early) is plinian pumice fall, intra-plinian pyroclastic flow and plinian pumice fall eruption phase, forming distal ash fall. Stage 2 (late) is final eruptional phase of the biggest pyroclastic flow of the Eb-Fukuda Tephra, forming a co-ignimbrite ash fall. Stage 3 is resedimented stage after the end of the explosive eruption. It is notable that resedimented volcaniclastic deposit reached Osaka sedimentary basin 300 km away from the eruption center. Om-SK110 Tephra erupted at about 1.65 Ma, divided into the stage 1, stage 2 and stage 3. Stage 1 is eruption phase of the plinian pumice fall and first pyroclastic flow. Stage 2 is pauses in eruption activity. Stage 3 is second pyroclastic flow phase, it is inferred that the pyroclastic flow of the stage 3 directly entered the Niigata sedimentary basin and simultaneously formed a co-ignimbrite ash. (author)

  3. Nitration of benzo[a]pyrene adsorbed on coal fly ash particles by nitrogen dioxide: role of thermal activation.

    Science.gov (United States)

    Kristovich, Robert L; Dutta, Prabir K

    2005-09-15

    Nitration of benzo[a]pyrene (BaP) by nitrogen dioxide (NO2) adsorbed on the surface of thermally activated coal fly ash and model aluminosilicate particles led to the formation of nitrobenzo[a]pyrenes as verified by extraction and gas chromatography/mass spectrometry (GC/MS). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was utilized to follow the nitration reaction on the surface of zeolite Y. Nitrobenzo[a]pyrene formation was observed along with the formation of nitrous acid and nitrate species. The formation of the BaP radical cation was also observed on thermally activated aluminosilicate particles by electron spin resonance (ESR) spectroscopy. On the basis of GC/MS, DRIFTS, and ESR spectroscopy results, a mechanism of nitration involving intermediate BaP radical cations generated on thermally activated aluminosilicate particles is proposed. These observations have led to the hypothesis that nitration of adsorbed polyaromatic hydrocarbons on coal fly ash by reaction with nitrogen oxides can occur in the smokestack, but with the aging of the fly ash particles, the extent of the nitration reaction will be diminished.

  4. Continuous production of nanostructured particles using spatial atomic layer deposition

    International Nuclear Information System (INIS)

    Ommen, J. Ruud van; Kooijman, Dirkjan; Niet, Mark de; Talebi, Mojgan; Goulas, Aristeidis

    2015-01-01

    In this paper, the authors demonstrate a novel spatial atomic layer deposition (ALD) process based on pneumatic transport of nanoparticle agglomerates. Nanoclusters of platinum (Pt) of ∼1 nm diameter are deposited onto titania (TiO 2 ) P25 nanoparticles resulting to a continuous production of an active photocatalyst (0.12–0.31 wt. % of Pt) at a rate of about 1 g min −1 . Tuning the precursor injection velocity (10–40 m s −1 ) enhances the contact between the precursor and the pneumatically transported support flows. Decreasing the chemisorption temperature (from 250 to 100 °C) results in more uniform distribution of the Pt nanoclusters as it decreases the reaction rate as compared to the rate of diffusion into the nanoparticle agglomerates. Utilizing this photocatalyst in the oxidation reaction of Acid Blue 9 showed a factor of five increase of the photocatalytic activity compared to the native P25 nanoparticles. The use of spatial particle ALD can be further expanded to deposition of nanoclusters on porous, micron-sized particles and to the production of core–shell nanoparticles enabling the robust and scalable manufacturing of nanostructured powders for catalysis and other applications

  5. Numerical Simulations of Particle Deposition in Metal Foam Heat Exchangers

    Science.gov (United States)

    Sauret, Emilie; Saha, Suvash C.; Gu, Yuantong

    2013-01-01

    Australia is a high-potential country for geothermal power with reserves currently estimated in the tens of millions of petajoules, enough to power the nation for at least 1000 years at current usage. However, these resources are mainly located in isolated arid regions where water is scarce. Therefore, wet cooling systems for geothermal plants in Australia are the least attractive solution and thus air-cooled heat exchangers are preferred. In order to increase the efficiency of such heat exchangers, metal foams have been used. One issue raised by this solution is the fouling caused by dust deposition. In this case, the heat transfer characteristics of the metal foam heat exchanger can dramatically deteriorate. Exploring the particle deposition property in the metal foam exchanger becomes crucial. This paper is a numerical investigation aimed to address this issue. Two-dimensional (2D) numerical simulations of a standard one-row tube bundle wrapped with metal foam in cross-flow are performed and highlight preferential particle deposition areas.

  6. The grain size dependency of vesicular particle shapes strongly affects the drag of particles. First results from microtomography investigations of Campi Flegrei fallout deposits

    Science.gov (United States)

    Mele, Daniela; Dioguardi, Fabio

    2018-03-01

    Acknowledging the grain size dependency of shape is important in volcanology, in particular when dealing with tephra produced and emplaced during and after explosive volcanic eruptions. A systematic measurement of the tridimensional shape of vesicular pyroclasts of Campi Flegrei fallout deposits (Agnano-Monte Spina, Astroni 6 and Averno 2 eruptions) varying in size from 8.00 to 0.016 mm has been carried out by means of X-Ray Microtomography. Data show that particle shape changes with size, especially for juvenile vesicular clasts, since it is dependent on the distribution and size of vesicles that contour the external clast outline. Two drag laws that include sphericity in the formula were used for estimating the dependency of settling velocity on shape. Results demonstrate that it is not appropriate to assume a size-independent shape for vesicular particles, in contrast with the approach commonly employed when simulating the ash dispersion in the atmosphere.

  7. Contributions of microbial activity and ash deposition to post-fire nitrogen availability in a pine savanna

    Science.gov (United States)

    Ficken, Cari D.; Wright, Justin P.

    2017-01-01

    Many ecosystems experience drastic changes to soil nutrient availability associated with fire, but the magnitude and duration of these changes are highly variable among vegetation and fire types. In pyrogenic pine savannas across the southeastern United States, pulses of soil inorganic nitrogen (N) occur in tandem with ecosystem-scale nutrient losses from prescribed burns. Despite the importance of this management tool for restoring and maintaining fire-dependent plant communities, the contributions of different mechanisms underlying fire-associated changes to soil N availability remain unclear. Pulses of N availability following fire have been hypothesized to occur through (1) changes to microbial cycling rates and (2) direct ash deposition. Here, we document fire-associated changes to N availability across the growing season in a longleaf pine savanna in North Carolina. To differentiate between possible mechanisms driving soil N pulses, we measured net microbial cycling rates and changes to soil δ15N before and after a burn. Our findings refute both proposed mechanisms: we found no evidence for changes in microbial activity, and limited evidence that ash deposition could account for the increase in ammonium availability to more than 5-25 times background levels. Consequently, we propose a third mechanism to explain post-fire patterns of soil N availability, namely that (3) changes to plant sink strength may contribute to ephemeral increases in soil N availability, and encourage future studies to explicitly test this mechanism.

  8. Development of a fluidized bed agglomeration modeling methodology to include particle-level heterogeneities in ash chemistry and granular physics

    Science.gov (United States)

    Khadilkar, Aditi B.

    The utility of fluidized bed reactors for combustion and gasification can be enhanced if operational issues such as agglomeration are mitigated. The monetary and efficiency losses could be avoided through a mechanistic understanding of the agglomeration process and prediction of operational conditions that promote agglomeration. Pilot-scale experimentation prior to operation for each specific condition can be cumbersome and expensive. So the development of a mathematical model would aid predictions. With this motivation, the study comprised of the following model development stages- 1) development of an agglomeration modeling methodology based on binary particle collisions, 2) study of heterogeneities in ash chemical composition and gaseous atmosphere, 3) computation of a distribution of particle collision frequencies based on granular physics for a poly-disperse particle size distribution, 4) combining the ash chemistry and granular physics inputs to obtain agglomerate growth probabilities and 5) validation of the modeling methodology. The modeling methodology comprised of testing every binary particle collision in the system for sticking, based on the extent of dissipation of the particles' kinetic energy through viscous dissipation by slag-liquid (molten ash) covering the particles. In the modeling methodology developed in this study, thermodynamic equilibrium calculations are used to estimate the amount of slag-liquid in the system, and the changes in particle collision frequencies are accounted for by continuously tracking the number density of the various particle sizes. In this study, the heterogeneities in chemical composition of fuel ash were studied by separating the bulk fuel into particle classes that are rich in specific minerals. FactSage simulations were performed on two bituminous coals and an anthracite to understand the effect of particle-level heterogeneities on agglomeration. The mineral matter behavior of these constituent classes was studied

  9. The energy deposition of slowing down particles in heterogeneous media

    International Nuclear Information System (INIS)

    Prinja, A.K.; Williams, M.M.R.

    1980-01-01

    Energy deposition by atomic particles in adjacent semi-infinite, amorphous media is described using the forward form of the Boltzmann transport equation. A transport approximation to the scattering kernel, developed elsewhere, incorporating realistic energy transfer is employed to assess the validity of the commonly used isotropic-scattering and straight-ahead approximations. Results are presented for integral energy deposition rates due to a plane, isotropic and monoenergetic source in one half-space for a range of mass ratios between 0.1 and 5.0. Integral profiles for infinite and semi-infinite media are considered and the influence of reflection for different mass ratios is evaluated. The dissimilar scattering properties of the two media induce a discontinuity at the interface in the energy deposition rate the magnitude of which is sensitive to the source position relative to the interface. A comprehensive evaluation of the total energy deposited in the source free medium is presented for a range of mass ratios and source positions. An interesting minimum occurs for off-interface source locations as a function of the source-medium mass ratio, the position of which varies with the source position but is insensitive to the other mass ratio. As a special case, energy reflection and escape coefficients for semi-infinite media are obtained which demonstrates that the effect of a vacuum interface is insignificant for deep source locations except for large mass ratios when reflection becomes dominant. (author)

  10. Residual Ash Formation during Suspension-Firing of Biomass

    DEFF Research Database (Denmark)

    Damø, Anne Juul; Jappe Frandsen, Flemming; Jensen, Peter Arendt

    2014-01-01

    Through 50+ years, high quality research has been conducted in order to characterize ash and deposit formation in utility boilers fired with coal, biomass and waste fractions. The basic mechanism of fly ash formation in suspension fired coal boilers is well described, documented and may even...... be modeled relatively precisely. Concerning fly ash formation from biomass or waste fractions, the situation is not nearly as good. Lots of data are available from campaigns where different ash fractions, including sometimes also in-situ ash, have been collected and analyzed chemically and for particle size...... distribution. Thus, there is a good flair of the chemistry of fly ash formed in plants fired with biomass or waste fractions, either alone, or in conjunction with coal. But data on dedicated studies of the physical size development of fly ash, are almost non-existing for biomasses and waste fractions...

  11. Characteristics of ash and particle emissions during bubbling fluidised bed combustion of three types of residual forest biomass.

    Science.gov (United States)

    Ribeiro, João Peres; Vicente, Estela Domingos; Alves, Célia; Querol, Xavier; Amato, Fulvio; Tarelho, Luís A C

    2017-04-01

    Combustion of residual forest biomass (RFB) derived from eucalypt (Eucalyptus globulus), pine (Pinus pinaster) and golden wattle (Acacia longifolia) was evaluated in a pilot-scale bubbling fluidised bed reactor (BFBR). During the combustion experiments, monitoring of temperature, pressure and exhaust gas composition has been made. Ash samples were collected at several locations along the furnace and flue gas treatment devices (cyclone and bag filter) after each combustion experiment and were analysed for their unburnt carbon content and chemical composition. Total suspended particles (TSP) in the combustion flue gas were evaluated at the inlet and outlet of cyclone and baghouse filter and further analysed for organic and elemental carbon, carbonates and 57 chemical elements. High particulate matter collection efficiencies in the range of 94-99% were observed for the baghouse, while removal rates of only 1.4-17% were registered for the cyclone. Due to the sand bed, Si was the major element in bottom ashes. Fly ashes, in particular those from eucalypt combustion, were especially rich in CaO, followed by relevant amounts of SiO 2 , MgO and K 2 O. Ash characteristics varied among experiments, showing that their inorganic composition strongly depends on both the biomass composition and combustion conditions. Inorganic constituents accounted for TSP mass fractions up to 40 wt%. Elemental carbon, organic matter and carbonates contributed to TSP mass fractions in the ranges 0.58-44%, 0.79-78% and 0.01-1.7%, respectively.

  12. The aggregation efficiency of very fine volcanic ash

    Science.gov (United States)

    Del Bello, E.; Taddeucci, J.; Scarlato, P.

    2013-12-01

    Explosive volcanic eruptions can discharge large amounts of very small sized pyroclasts (under 0.090 mm) into the atmosphere that may cause problems to people, infrastructures and environment. The transport and deposition of fine ash are ruled by aggregation that causes premature settling of fine ash and, as consequence, significantly reduces the concentration of airborne material over long distances. Parameterizing the aggregation potential of fine ash is then needed to provide accurate modelling of ash transport and deposition from volcanic plumes. Here we present the first results of laboratory experiments investigating the aggregation efficiency of very fine volcanic particles. Previous laboratory experiments have shown that collision kinetic and relative humidity provide the strongest effect on aggregation behaviour but were only limited to particles with size > 0.125 mm. In our work, we focus on natural volcanic ash at ambient humidity with particles size aggregation potential. Two types of ash were used in our experiments: fresh ash, collected during fall-out from a recent plume-forming eruption at Sakurajima (Japan -July 2013) and old ash, collected from fall-out tephra deposits at Campi Flegrei (Italy, ca. 10 ka), to account for the different chemical composition and morphoscopic effects of altered ash on aggregation efficiency. Total samples were hand sieved to obtain three classes with unimodal grain size distributions (sieved from the top of a transparent tank where a fan, placed at the bottom, allows turbulent dispersion of particles. Collision and sticking of particles on a vertical glass slide were filmed with a high speed cameras at 6000 fps. Our lenses arrangement provide high image resolution allowing to capture particles down to 0.005 mm in diameter. Video sequences of particles motion and collision were then processed with image analysis and particle tracking tools to determine i) the particle number density and ii) the grain size distribution

  13. Particle dry deposition to water surfaces: Processes and consequences

    DEFF Research Database (Denmark)

    Pryor, S.C.; Barthelmie, R.J.

    2000-01-01

    flux to coastal waters, atmosphere-surface exchange represents a significant component of the total flux and may be particularly critical during the summertime when both the riverine input and ambient nutrient concentrations are often at a minimum. In this chapter, we present an overview...... of the physical and chemical processes which dictate the quantity (and direction) of atmosphere-surface fluxes of trace chemicals to (and above) water surfaces with particular emphasis on the role of particles. Dry deposition (transfer to the surface in the absence of precipitation) of particles is determined...... efforts to simulate and measure fluxes close to the coastline. These arise in part from the complexity of atmospheric flow in this region where energy and chemical fluxes are highly inhomogeneous in space and time and thermally generated atmospheric circulations are commonplace. (C) 2000 Elsevier Science...

  14. Particle deposition and clearance of atmospheric particles in the human respiratory tract during LACE 98

    Science.gov (United States)

    Bundke, U.; Hänel, G.

    2003-04-01

    During the LACE 98footnote{Lindenberg Aerosol Characterization Experiment, (Germany) 1998} experiment microphysical, chemical and optical properties of atmospheric particles were measured by several groups. (Bundke et al.). The particle deposition and clearance of the particles in the human respiratory tract was calculated using the ICRP (International Commission on Radiological Protection) deposition and clearance model (ICRP 1994). Particle growth as function of relative humidity outside the body was calculated from measurement data using the model introduced by Bundke et al.. Particle growth inside the body was added using a non-equilibrium particle growth model. As a result of the calculations, time series of the total dry particle mass and -size distribution were obtained for all compartments of the human respiratory tract defined by ICRP 1994. The combined ICRP deposition and clearance model was initialized for different probationers like man, woman, children of different ages and several circumstances like light work, sitting, sleeping etc. Keeping the conditions observed during LACE 98 constant a approximation of the aerosol burdens of the different compartments was calculated up to 4 years of exposure and compared to the results from Snipes et al. for the "Phoenix" and "Philadelphia" aerosol. References: footnotesize{ Bundke, U. et al.,it{Aerosol Optical Properties during the Lindenberg Aerosol Characterization Experiment (LACE 98)} ,10.1029/2000JD000188, JGR, 2002 ICRP,it{Human Respiratory Tract Model for Radiological Protection, Bd. ICRP Publication 66}, Annals of the ICRP, 24,1-3, Elsevier Science, Ocford, 1994 Snipes et al. ,it{The 1994 ICRP66 Human Respiratory Tract Model as a Tool for predicting Lung Burdens from Exposure to Environmental Aerosols}, Appl. Occup. Environ. Hyg., 12, 547-553,1997}

  15. Volcanic Ash Data Assimilation System for Atmospheric Transport Model

    Science.gov (United States)

    Ishii, K.; Shimbori, T.; Sato, E.; Tokumoto, T.; Hayashi, Y.; Hashimoto, A.

    2017-12-01

    The Japan Meteorological Agency (JMA) has two operations for volcanic ash forecasts, which are Volcanic Ash Fall Forecast (VAFF) and Volcanic Ash Advisory (VAA). In these operations, the forecasts are calculated by atmospheric transport models including the advection process, the turbulent diffusion process, the gravitational fall process and the deposition process (wet/dry). The initial distribution of volcanic ash in the models is the most important but uncertain factor. In operations, the model of Suzuki (1983) with many empirical assumptions is adopted to the initial distribution. This adversely affects the reconstruction of actual eruption plumes.We are developing a volcanic ash data assimilation system using weather radars and meteorological satellite observation, in order to improve the initial distribution of the atmospheric transport models. Our data assimilation system is based on the three-dimensional variational data assimilation method (3D-Var). Analysis variables are ash concentration and size distribution parameters which are mutually independent. The radar observation is expected to provide three-dimensional parameters such as ash concentration and parameters of ash particle size distribution. On the other hand, the satellite observation is anticipated to provide two-dimensional parameters of ash clouds such as mass loading, top height and particle effective radius. In this study, we estimate the thickness of ash clouds using vertical wind shear of JMA numerical weather prediction, and apply for the volcanic ash data assimilation system.

  16. Kinematics of flow and sediment particles at entrainment and deposition

    Science.gov (United States)

    Antico, Federica; Sanches, Pedro; Aleixo, Rui; Ferreira, Rui M. L.

    2015-04-01

    A cohesionless granular bed subjected to a turbulent open-channel flow is analysed. The key objective is to clarify the kinematics of entrainment and deposition of individual sediment particles. In particular, we quantify a) the turbulent flow field in the vicinity of particles at the instants of their entrainment and of their deposition; b) the initial particle velocity and the particle velocity immediately before returning to rest. The experimental work was performed at the Hydraulics Laboratory of IST-UL in a 12.5 m long, 0.405 m wide glass-walled flume recirculating water and sediment through independent circuits. The granular bed was a 4.0 m long and 2.5 cm deep reach filled with 5 mm diameter glass beads packed (with some vibration) to a void fraction of 0.356, typical of random packing. Upstream the mobile bed reach the bed was composed of glued particles to ensure the development of a boundary layer with the same roughness. Laboratory tests were run under conditions of weak beadload transport with Shields parameters in the range 0.007 to 0.03. Froude numbers ranged from 0.63 to 0.95 while boundary Reynolds numbers were in the range 130 to 300. It was observed that the bed featured patches of regular arrangements: face centered cubic (fcc) or hexagonal close packing (hcp) blocks alternate with and body centered cubic (bcc) blocks. The resulting bed surface exhibits cleavage lines between blocks and there are spatial variations of bed elevation. The option for artificial sediment allowed for a simplified description of particle positioning at the instant of entrainment. In particular support and pivoting angles are found analytically. Skin friction angles were determind experimentally. The only relevant variables are exposure (defined as the ratio of the actual frontal projection of the exposed area to the area of a circle with 5 mm diameter) and protrusion (defined as the vertical distance between the apex of the particle and the mean local bed elevation

  17. Analytical model for erosion behaviour of impacted fly-ash particles ...

    Indian Academy of Sciences (India)

    Mathematical model; erosion rate; boiler components; fly ash ... sion, together with the processes of blocking, fouling and corrosion, shortens the service-life of boiler ..... Jun Y D, Tabakoff W 1994 Numerical simulation of a dilute particulate flow ...

  18. Estimating rates of decompression from textures of erupted ash particles produced by 1999-2006 eruptions of Tungurahua volcano, Ecuador

    Science.gov (United States)

    Wright, Heather M.N.; Cashman, Katharine V.; Mothes, Patricia A.; Hall, Minard L.; Ruiz, Andrés Gorki; Le Pennec, Jean-Luc

    2012-01-01

    Persistent low- to moderate-level eruptive activity of andesitic volcanoes is difficult to monitor because small changes in magma supply rates may cause abrupt transitions in eruptive style. As direct measurement of magma supply is not possible, robust techniques for indirect measurements must be developed. Here we demonstrate that crystal textures of ash particles from 1999 to 2006 Vulcanian and Strombolian eruptions of Tungurahua volcano, Ecuador, provide quantitative information about the dynamics of magma ascent and eruption that is difficult to obtain from other monitoring approaches. We show that the crystallinity of erupted ash particles is controlled by the magma supply rate (MSR); ash erupted during periods of high magma supply is substantially less crystalline than during periods of low magma supply. This correlation is most easily explained by efficient degassing at very low pressures (<<50 MPa) and degassing-driven crystallization controlled by the time available prior to eruption. Our data also suggest that the observed transition from intermittent Vulcanian explosions at low MSR to more continuous periods of Strombolian eruptions and lava fountains at high MSR can be explained by the rise of bubbles through (Strombolian) or trapping of bubbles beneath (Vulcanian) vent-capping, variably viscous (and crystalline) magma.

  19. Evaluation of physicochemical properties of radioactive cesium in municipal solid waste incineration fly ash by particle size classification and leaching tests.

    Science.gov (United States)

    Fujii, Kengo; Ochi, Kotaro; Ohbuchi, Atsushi; Koike, Yuya

    2018-07-01

    After the Fukushima Daiichi-Nuclear Power Plant accident, environmental recovery was a major issue because a considerable amount of municipal solid waste incineration (MSWI) fly ash was highly contaminated with radioactive cesium. To the best of our knowledge, only a few studies have evaluated the detailed physicochemical properties of radioactive cesium in MSWI fly ash to propose an effective method for the solidification and reuse of MSWI fly ash. In this study, MSWI fly ash was sampled in Fukushima Prefecture. The physicochemical properties of radioactive cesium in MSWI fly ash were evaluated by particle size classification (less than 25, 25-45, 45-100, 100-300, 300-500, and greater than 500 μm) and the Japanese leaching test No. 13 called "JLT-13". These results obtained from the classification of fly ash indicated that the activity concentration of radioactive cesium and the content of the coexisting matter (i.e., chloride and potassium) temporarily change in response to the particle size of fly ash. X-ray diffraction results indicated that water-soluble radioactive cesium exists as CsCl because of the cooling process and that insoluble cesium is bound to the inner sphere of amorphous matter. These results indicated that the distribution of radioactive cesium depends on the characteristics of MSWI fly ash. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Labeling suspended aerosol particles with short-lived radionuclides for determination of particle deposition

    International Nuclear Information System (INIS)

    Smith, M.F.; Bryant, S.; Welch, S.; Digenis, G.A.

    1984-01-01

    Radiotracer techniques were developed to examine parameters that characterize pressurized aerosols designed to deliver insoluble particles suspended in the aerosol formulation. Microaggregated bovine serum albumin microspheres that were to be suspended were labeled with iodine-131 (t1/2 . 8 d). This iodination procedure (greater than 80% effective) is also applicable to iodine-123, which possesses superior characteristics for external imaging and further in vivo studies. This report shows that for pressurized aerosols containing suspended particles, each metered dose is approximately equal (not including the priming doses and the emptying doses). Increase in the delivery of the albumin particles out of the canister was best achieved by pretreating the valve assembly with a solution of 2% (w/v) bovine serum albumin in phosphate buffer. Use of a cascade impactor delineated the particle size distribution of the micropheres, with the majority of particles ranging in size from 2 to 8 microns. The data disclosed here indicate that the techniques developed with short-lived radionuclides can be used to quantitate each metered dose, characterize the particle size distribution profile of the aerosol contents, and determine the extent of deposition of the particles in the aerosol canister and all of its components

  1. Physiological effect of accidental fly ash deposition on plants and chemical study of the dusted plant leaves by XRP and EPMA

    Energy Technology Data Exchange (ETDEWEB)

    Osan, J.; Torok, S.; Torok, K.; Nemeth, L.; Labar, J.L. [KFTI Atomic Energy Research Institute, Budapest (Hungary)

    1996-07-01

    Studies on the influence of fly ash on the photosynthetic activity of Solidago canadensis L. were carried out in order to determine the importance of this material as an environmental impact agent. Leaf samples were dusted with fly ash and sprayed with water of different pH values simulating acid rain. Fly ash was applied in quantities to model an accidental occasion of an extremely high emission level of fly ash as a result of malfunctioning of the electrostatic filters of fossil fuel-burning power plants. Leaf samples were analysed to trace the distribution of fly ash compounds on the leaf epidermis by means of x-ray fluorescence (XRF) analysis and single-particle electron probe microanalysis (EPMA). Significant reduction of the photosynthetic activity compared with the control group was observed only when the dusted plants were sprayed with acid rain. The trace element study showed that the uptake of toxic elements by plants was not significant. A quartz microcrystal layer in the case of acid treatment was detected by EPMA, and covered the entire leaf surface. It is considered that this layer, in addition to the fly ash particles themselves, absorbed light significantly, which played an important role in the decrease in photosynthetic activity.

  2. The Effect of Applied Organic Fertilizers on the Bioavailability of Heavy Metals in Lolium Perenne, Cultivated on Fly Ash Deposits

    Directory of Open Access Journals (Sweden)

    Smaranda Mâşu

    2011-10-01

    Full Text Available The study aims to monitor the capacity of certain organic fertilizers (volcanic tuff and municipal sludge, applied as such and mixed with volcanic rocks with a high content in clinoptilolite, to determine the covering with vegetation of fly ash deposits resulted from the combustion of lignite in thermal plants. Both biosolids (20 t/ha and volcanic rock with high clinoptilolite content (5 t/ha determined the installation of a vegetative layer and diminished the soil metal bioavailability to the Lolium prerenne plant biomass. When using the organic-zeolite mixture, a synergistic effect is recorded of the two components of the treatment agent and an increase of the biomass with 448%. Moreover, the resulted biomass shows the highest reductions of metal bioaccumulations, of 38-46% for Zn and Fe, of 62% for Cu and between 82-89% for Cr, Ni and Pb.

  3. Exposure to toxicants in soil and bottom ash deposits in Agbogbloshie, Ghana: human health risk assessment.

    Science.gov (United States)

    Obiri, S; Ansa-Asare, O D; Mohammed, S; Darko, H F; Dartey, A G

    2016-10-01

    Recycling of e-waste using informal or crude techniques poses serious health risk not only to the workers but also to the environment as whole. It is against this background that this paper sought to measure health risk faced by informal e-waste workers from exposure to toxicants such as lead, cadmium, chromium, copper, arsenic, tin, zinc and cobalt via oral and dermal contact with bottom ash and soil. Using random sampling techniques, 3 separate sites each (where burning and manual dismantling of e-wastes are usually carried) were identified, and a total of 402 samples were collected. The samples were analysed using standard methods for chemical analysis prescribed by the American Water Works Association (AWWA). Concentrations of Pb, Cd, Cr, Cu, As, Sn, Zn and Co in bottom ash samples from location ASH1 are 5388 ± 0.02 mg/kg (Pb), 2.39 ± 0.01 mg/kg (Cd), 42 ± 0.05 mg/kg (Cr), 7940 ± 0.01 mg/kg (Cu), 20 ± 0.07 mg/kg (As), 225 ± 0.04 mg/kg (Sn), 276 ± 0.04 mg/kg (Zn) and 123 ± 0.04 mg/kg (Co), while concentrations of the aforementioned toxicants in soil samples at location ASG1 are as follows: 1685 ± 0.14 mg/kg (Pb), 26.89 ± 0.30 mg/kg (Cd), 36.86 ± 0.02 mg/kg (Cr), 1427 ± 0.08 mg/kg (Cu), 1622 ± 0.12 mg/kg (As), 234 ± 0.25 mg/kg (Sn), 783 ± 0.31 mg/kg (Zn) and 135 ± 0.01 mg/kg (Co); used as input parameters in assessing health risk faced by workers. The results of cancer health risk faced by e-waste workers due to accidental ingestion of As in bottom ash at ASH1 is 4.3 × 10 -3 (CTE) and 6.5 × 10 -2 (RME), i.e. approximately 4 out of 1000 e-waste workers are likely to suffer from cancer-related diseases via central tendency exposure (CTE parameters), and 7 out of every 100 e-waste worker is also likely to suffer from cancer cases by reasonable maximum exposure (RME) parameters, respectively. The cancer health risk results for the other sampling sites were found to have exceeded the acceptable

  4. CFD modeling of ash deposition for co-combustion of MBM with coal in a tangentially fired utility boiler

    NARCIS (Netherlands)

    Taha, T.J.; Stam, A.F.; Stam, K.; Brem, Gerrit

    2013-01-01

    Ash deposition is one of the main challenges that needs to be tackled in response to increased percentage of biomass co-firing in pulverized fuel boilers. In this study, a model has been developed to investigate the slagging behavior of meat and bone meal (MBM) at higher co-firing rates in the

  5. NRPB volunteer study: deposition and clearance of inhaled particles

    International Nuclear Information System (INIS)

    Etherington, G.; Smith, J.

    1996-01-01

    At the Board Meeting of the National Radiological Protection Board held on 15 February 1996, approval was given for an experimental study of the deposition and clearance of inhaled particles in the human nasal passage. This is the latest in a series of volunteer biokinetic studies that have been conducted at NRPB since its formation. This article explains the purpose of the study, how ethical approval was obtained, how the study will be performed, what volunteers will be asked to do, and what doses they will receive. Doses will of course be carefully controlled, and will be well below the annual limits set for such experiments. The success of the study is of course crucially dependent on recruitment of a sufficient number of volunteers. The aim of this article is to provide information to anyone who might be interested in volunteering. (UK)

  6. Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

    International Nuclear Information System (INIS)

    Talebizadeh, P.; Rahimzadeh, H.; Ahmadi, G.; Brown, R.; Inthavong, K.

    2016-01-01

    Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

  7. Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

    Energy Technology Data Exchange (ETDEWEB)

    Talebizadeh, P.; Rahimzadeh, H., E-mail: rahimzad@aut.ac.ir [Amirkabir University of Technology, Department of Mechanical Engineering (Iran, Islamic Republic of); Ahmadi, G. [Clarkson University, Department of Mechanical and Aeronautical Engineering (United States); Brown, R. [Queensland University of Technology, Biofuel Engine Research Facility (Australia); Inthavong, K. [RMIT University, School of Aerospace, Mechanical and Manufacturing Engineering (Australia)

    2016-12-15

    Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

  8. Differential pulmonary inflammation and in vitro cytotoxicity of size-fractionated fly ash particles from pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    M. Ian Gilmour; Silvia O' Connor; Colin A.J. Dick; C. Andrew Miller; William P. Linak [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). National Health and Environmental Effects Research Laboratory

    2004-03-01

    Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 {mu}g of ultrafine ({lt}0.2 {mu}m), fine ({lt}2.5 {mu}m), and coarse ({gt}2.5 {mu}m) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content. 42 refs., 5 figs., 3 tabs.

  9. The Influence of Particle Size, Fluidization Velocity, and Fuel Type on Ash-Induced Agglomeration in Biomass Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Gatternig, Bernhard, E-mail: bernhard.gatternig@cbi.uni-erlangen.de; Karl, Jürgen [Chair of Energy Process Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Nuremberg (Germany)

    2014-11-19

    Agglomeration of the bed material is one of the main obstacles for biomass utilization in fluidized bed combustors. Especially, high-potential fuels such as fast growing energy crops or biogeneous residues are affected because of their high content of alkaline metals. Despite ongoing research efforts, the knowledge base on what fuels are affected is still limited. This paper describes the design and installation of two lab-scale reactors for the experimental determination of agglomeration temperatures. The reactor concept and measurement method were developed under consideration of experiences from existing test rigs published in literature. Preliminary tests confirmed a reproducibility of ±5°C for both new reactors. The results of an extended measurement campaign (156 test runs of 25 fuel species at a wide range of the operational parameters “bed particle size,” “gas velocity,” and “bed ash accumulation”), based on “design of experiment” (DoE) criteria, showed high-agglomeration tendencies for residues (e.g., dried distillery grains, corn cobs) while woody energy crops (e.g., willow, alder) exhibited very stable combustion behavior. The operating parameters influenced the agglomeration behavior to a lesser degree than different ash compositions of fuel species tested. An interpolation within the DoE factor space allowed for a subsequent comparison of our results with experiments reported in literature. Good agreement was reached for fuels of comparable ash composition considering the interpolation errors of ±32°C on average.

  10. REGIONAL DEPOSITION OF COARSE PARTICLES AND VENTILATION DISTRIBUTION IN PATIENTS WITH CYSTIC FIBROSIS

    Science.gov (United States)

    The efficacy of inhaled pharmaceuticals depends, in part, on their site of respiratory deposition. Markedly nonuniform ventilation distribution may occur in persons with obstructive airways diseases and may affect particle deposition. We studied the relationship between regional ...

  11. Deposition of magnetite particles from high velocity water onto isothermal tubes

    International Nuclear Information System (INIS)

    Burrill, K.A.

    1977-02-01

    The deposition rate of magnetite particles from a high velocity water slurry onto isothermal metal tubes was measured. The effects of velocity (5 to 100 m/s), slurry concentration (200 to 1000 mg Fe/kg H 2 O), temperature (25 0 to 90 0 C), pH (4 to 10 at 25 0 C), and tube material (nickel, Zircaloy-4) on deposition rate were studied. The data are interpreted in terms of two steps in series for deposition: a mass transfer step followed by a deposition or inertial coasting step. Mass transfer of particles through the bulk water phase apparently limits the deposition of particles at high Reynolds number

  12. Particle deposition due to turbulent diffusion in the upper respiratory system

    Science.gov (United States)

    Hamill, P.

    1979-01-01

    Aerosol deposition in the upper respiratory system (trachea to segmental bronchi) is considered and the importance of turbulent diffusion as a deposition mechanism is evaluated. It is demonstrated that for large particles (diameter greater than about 5 microns), turbulent diffusion is the dominant deposition mechanism in the trachea. Conditions under which turbulent diffusion may be important in successive generations of the pulmonary system are determined. The probability of particle deposition is compared with probabilities of deposition, as determined by the equations generally used in regional deposition models. The analysis is theoretical; no new experimental data is presented.

  13. Lung dynamics of aerosol particles with special reference to deposition model

    International Nuclear Information System (INIS)

    Takahashi, Kanji

    1977-01-01

    A movement of aerosol particles in the lungs, which was inhaled into the respiratory organ was given an outline by means of technological deposition model. The respiratory organ was considered to be one airway system, and was divided into nasopharyngeal part, trachea-bronchial part, and pulmonary part. The transport of particles in the respiratory tract was explained by mentioning structual model of the airway system, standard respiratory flow, and distribution of flow speed in the respiratory tract. It was explained that particle deposition in the respiratory tract seemed to be caused by inertia impact at bifurcation, gravity deposition and scattering deposition at tubular wall, interruption effect in nasopharyngeal part, and scattering phoresis effect in the upper respiratory tract or gas exchange part. Furthermore, an outline of calculation of the deposition amount of particles was described from a standpoint of the above-mentioned structure, breathing air flow, and deposition structure of particles. (Kanao, N.)

  14. Impact of super-distal ash fallout on tropical hydrology and landscape: a case study from the YTT deposits of the Perak river, Malaysia

    Science.gov (United States)

    Gatti, E.; Saidin, M.; Gibbard, P.; Oppenheimer, C.

    2011-12-01

    The Younger Toba Tuff eruption, approximately 73 ka ago, is the largest known for the Quaternary and its climate, environmental and human consequences are keenly debated (Oppenheimer, 2011).While the distribution (Rose and Chesner, 1987; Rose and Chesner, 1990; Chesner et al., 1991; Schulz et al., 2002; Von Rad et al., 2002) , geochemical properties (Shane et al., 1995; Westgate et al., 1998) and volcanic significance (Rampino and Self, 1982; Rampino and Self, 1993; Rampino and Ambrose, 2000; Oppenheimer, 2002; Mason et al., 2004)of the YTT have been widely studied, few attention has been given to the significance of the distal volcanic ash deposits within their receiving basin context. Although several studies exist on the impact of pyroclastic flows on proximal rivers and lakes (Collins and Dunne, 1986; Thompson et al., 1986; Hayes et al., 2002; Németh and Cronin, 2007), only few address the issues of the dynamic of preservation of super-distal fine ash deposits in rivers (also due to the lack of direct data on super-eruptions). It has also been demonstrated that models of the styles and timing of distal volcanoclastic re-sedimentation are more complicated than those developed for proximal settings of stratovolcanoes (Kataoka et al., 2009). We present an analysis of the taphonomy (intended as accumulation and preservation) of distal volcanic ash in fluvial and lacustrian contexts in newly discovered Toungest Toba Tuff sites in the Lenggong valley, western Peninsular Malaysia. The paper aims to characterise the nature of distal tephras in fluvial environments towards a stratigraphic distinction between primary ash and secondary ash, characterisation of the pre-ash fall receiving environment in term of fluvial dynamic and landscape morphology, and assessment of the time of recovery.

  15. Melting and Sintering of Ashes

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug

    1997-01-01

    -1300°C, and a trend of higher fusion temperatures with increasing contents of Al-silicates and quartz was found.c) Fly ashes, bottom ashes and deposits from coal/straw co-firing were all found to consist mainly of metal-alumina and alumina-silicates. These ashes all melt in the temperature range 1000......The thesis contains an experimental study of the fusion and sintering of ashes collected during straw and coal/straw co-firing.A laboratory technique for quantitative determination of ash fusion has been developed based on Simultaneous Thermal Analysis (STA). By means of this method the fraction......, the biggest deviations being found for salt rich (i.e. straw derived) ashes.A simple model assuming proportionality between fly ash fusion and deposit formation was found to be capable of ranking deposition rates for the different straw derived fly ashes, whereas for the fly ashes from coal/straw co-firing...

  16. Particle deposition from aqueous suspensions in turbulent pipe flow - a comparison of observed deposition rates and predicted arrival rates

    International Nuclear Information System (INIS)

    Rodliffe, R.S.

    1979-11-01

    At the present time, there appear to be only four adequately controlled and characterised experimental studies of particle deposition from single phase water in turbulent pipe flow. These are used to illustrate the ranges of applicability of methods for predicting particle arrival rates at tube walls. Arrival rates are predicted from mass transfer correlations and the theory of Reeks and Skyrme (1976) when transport is limited by Brownian diffusion and inertial behaviour, respectively. The regimes in which finite particle size limits the application of these methods are defined and preliminary consideration is given to the conditions under which gravitational settling may make a contribution to deposition in vertically mounted tubes. (author)

  17. Concurrent Modeling of Hydrodynamics and Interaction Forces Improves Particle Deposition Predictions.

    Science.gov (United States)

    Jin, Chao; Ren, Carolyn L; Emelko, Monica B

    2016-04-19

    It is widely believed that media surface roughness enhances particle deposition-numerous, but inconsistent, examples of this effect have been reported. Here, a new mathematical framework describing the effects of hydrodynamics and interaction forces on particle deposition on rough spherical collectors in absence of an energy barrier was developed and validated. In addition to quantifying DLVO force, the model includes improved descriptions of flow field profiles and hydrodynamic retardation functions. This work demonstrates that hydrodynamic effects can significantly alter particle deposition relative to expectations when only the DLVO force is considered. Moreover, the combined effects of hydrodynamics and interaction forces on particle deposition on rough, spherical media are not additive, but synergistic. Notably, the developed model's particle deposition predictions are in closer agreement with experimental observations than those from current models, demonstrating the importance of inclusion of roughness impacts in particle deposition description/simulation. Consideration of hydrodynamic contributions to particle deposition may help to explain discrepancies between model-based expectations and experimental outcomes and improve descriptions of particle deposition during physicochemical filtration in systems with nonsmooth collector surfaces.

  18. Electrical Field Guided Electrospray Deposition for Production of Gradient Particle Patterns.

    Science.gov (United States)

    Yan, Wei-Cheng; Xie, Jingwei; Wang, Chi-Hwa

    2018-06-06

    Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

  19. Role of hydrotreating products in deposition of fine particles in reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Chung, K.; Gray, M.R. [University of Alberta, Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2001-06-11

    Hydrotreating reactions may affect the deposition of fine particles, which can eventually lead to reactor plugging. The deposition of fine particles from gas oil was measured in an internally recirculating reactor at 375{degree}C under hydrogen. H{sub 2}S from hydrodesulfurization would convert corrosion products to metal sulfides. Iron sulfide deposited rapidly in the packed bed because the mineral surface did not retain a stabilizing layer of asphaltenic material. Addition of water, to test the role of hydrodeoxygenation, doubled the deposition of clay particles by reducing the surface coating of organic material. Neither ammonia or quinoline had any effect on particle deposition, therefore, hydrodenitrogenation did not affect particle behavior. 16 refs., 4 figs., 3 tabs.

  20. Experimental studies on pulp and paper mill sludge ash behavior in fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Latva-Somppi, J. [VTT Chemical Technology, Espoo (Finland). Process Technology

    1998-11-01

    Ash formation during the fluidized bed combustion (FBC) of pulp and paper mill sludges has been experimentally studied on an industrial and bench scale. The methods included aerosol measurements, chemical and crystalline composition analyses, thermogravimetry and electron microscopy. Fly ash mass and number size distributions and elemental enrichment in submicron particles and bottom ash were measured. Fly ash, bottom ash and ash deposits were characterized and their formation mechanisms are discussed. During combustion the fine paper-making additives in sludge, clay minerals and calcite, sintered fanning porous agglomerates. The fly ash mass mean size was 7.5 - 15 lam and the supermicron particles included 93.6 - 97.3 % of the fly ash. Condensation of the volatilized inorganic species formed spherical submicron particles in the fly ash. Their mass concentration was almost negligible when co-firing paper mill sludges and wood. This suggests that the fraction of the volatilized inorganic species in the paper mill sludges was low. Results from pulp mill sludge and bark co-firing were different. A clear mass mode below 0.3 pm, presenting 2.2 - 5.0 weight-% of the fly ash was detected. The condensed species included K, Na, S and Cl. Their mass fraction was higher in the pulp mill sludge than in the paper mill sludge. Evidently this resulted in increased volatilization and formation of condensed particles. The following trace elements were enriched in the submicron ash during pulp mill sludge and wood co-firing: As, Cd, Rb and Pb. The main part of the volatile species was, however, captured in the bulk ash. Presumably, this was due to the high surface area concentration in the bulk ash. Sludge moisture was observed to reduce the inorganic species volatilization. Probably steam vaporization from the wet sludge through the burning layer decreased combustion temperatures on char surface and less char was produced. Hence, the volatilization of ash forming species was

  1. Adjusting particle-size distributions to account for aggregation in tephra-deposit model forecasts

    Science.gov (United States)

    Mastin, Larry G.; Van Eaton, Alexa; Durant, A.J.

    2016-01-01

    Volcanic ash transport and dispersion (VATD) models are used to forecast tephra deposition during volcanic eruptions. Model accuracy is limited by the fact that fine-ash aggregates (clumps into clusters), thus altering patterns of deposition. In most models this is accounted for by ad hoc changes to model input, representing fine ash as aggregates with density ρagg, and a log-normal size distribution with median μagg and standard deviation σagg. Optimal values may vary between eruptions. To test the variance, we used the Ash3d tephra model to simulate four deposits: 18 May 1980 Mount St. Helens; 16–17 September 1992 Crater Peak (Mount Spurr); 17 June 1996 Ruapehu; and 23 March 2009 Mount Redoubt. In 192 simulations, we systematically varied μagg and σagg, holding ρagg constant at 600 kg m−3. We evaluated the fit using three indices that compare modeled versus measured (1) mass load at sample locations; (2) mass load versus distance along the dispersal axis; and (3) isomass area. For all deposits, under these inputs, the best-fit value of μagg ranged narrowly between  ∼  2.3 and 2.7φ (0.20–0.15 mm), despite large variations in erupted mass (0.25–50 Tg), plume height (8.5–25 km), mass fraction of fine ( discrete process that is insensitive to eruptive style or magnitude. This result offers the potential for a simple, computationally efficient parameterization scheme for use in operational model forecasts. Further research may indicate whether this narrow range also reflects physical constraints on processes in the evolving cloud.

  2. Reactivity of surface of metal oxide particles: from adsorption of ions to deposition of colloidal particles

    International Nuclear Information System (INIS)

    Lefevre, Gregory

    2010-01-01

    In this Accreditation to supervise research (HDR), the author proposes an overview of his research works in the field of chemistry. These works more particularly addressed the understanding of the surface reactivity of metal oxide particles and its implication on sorption and adherence processes. In a first part, he addresses the study of surface acidity-alkalinity: measurement of surface reactivity by acid-base titration, stability of metal oxides in suspension, effect of morphology on oxide-hydroxide reactivity. The second part addresses the study of sorption: reactivity of iron oxides with selenium species, sorption of sulphate ions on magnetite, attenuated total reflection infrared spectroscopy (ATR-IR). Adherence effects are addressed in the third part: development of an experimental device to study adherence in massive substrates, deposition of particles under turbulent flow. The last part presents a research project on the effect of temperature on ion sorption at solids/solutions interfaces, and on the adherence of metal oxide particles. The author gives his detailed curriculum, and indicates his various publications, teaching activities, research and administrative responsibilities

  3. Estimating chemical composition of atmospheric deposition fluxes from mineral insoluble particles deposition collected in the western Mediterranean region

    Directory of Open Access Journals (Sweden)

    Y. Fu

    2017-11-01

    Full Text Available In order to measure the mass flux of atmospheric insoluble deposition and to constrain regional models of dust simulation, a network of automatic deposition collectors (CARAGA has been installed throughout the western Mediterranean Basin. Weekly samples of the insoluble fraction of total atmospheric deposition were collected concurrently on filters at five sites including four on western Mediterranean islands (Frioul and Corsica, France; Mallorca, Spain; and Lampedusa, Italy and one in the southern French Alps (Le Casset, and a weighing and ignition protocol was applied in order to quantify their mineral fraction. Atmospheric deposition is both a strong source of nutrients and metals for marine ecosystems in this area. However, there are few data on trace-metal deposition in the literature, since their deposition measurement is difficult to perform. In order to obtain more information from CARAGA atmospheric deposition samples, this study aimed to test their relevance in estimating elemental fluxes in addition to total mass fluxes. The elemental chemical analysis of ashed CARAGA filter samples was based on an acid digestion and an elemental analysis by inductively coupled plasma atomic emission spectroscopy (ICP-AES and mass spectrometry (MS in a clean room. The sampling and analytical protocols were tested to determine the elemental composition for mineral dust tracers (Al, Ca, K, Mg and Ti, nutrients (P and Fe and trace metals (Cd, Co, Cr, Cu, Mn, Ni, V and Zn from simulated wet deposition of dust analogues and traffic soot. The relative mass loss by dissolution in wet deposition was lower than 1 % for Al and Fe, and reached 13 % for P due to its larger solubility in water. For trace metals, this loss represented less than 3 % of the total mass concentration, except for Zn, Cu and Mn for which it could reach 10 %, especially in traffic soot. The chemical contamination during analysis was negligible for all the elements except for Cd

  4. Ash Properties of Alternative Biomass

    DEFF Research Database (Denmark)

    Capablo, Joaquin; Jensen, Peter Arendt; Pedersen, Kim Hougaard

    2009-01-01

    analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence...... on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion....

  5. Deposition of particle-bound radionuclides in dry weather, fog, rain and snowfall

    International Nuclear Information System (INIS)

    Oberschachtsiek, D.; Sparmacher, H.; Kreh, R.; Adam, M.; Fuelber, K.; Stegger, J.; Bonka, H.

    1992-01-01

    Radionuclides emitted from nuclear plants and installations are transported in dry weather, because of turbulences and sedimentations, to plant parts above ground and near the ground and to other areas, and deposited there. The deposited activity is proportional to the activity concentration near the deposition area. In the case of particle-bound radionuclides it depends on the aerodynamic particle diameter, surface quality and other factors. In a large number of experiments deposition velocity was measured. In fog the particles to which radionuclides are bound grow by coagulation and condensation. The aerosol size spectrum changes with increasing distance from the place of emission. The type of the fog and the form of the emitted spectrum are important factors which influence this process. With normal activity distributions as a function of the aerodynamic particle diameter, the deposition velocity increases with the distance from the place of emission, up to a final value, due to the shift of the spectrum to larger diameters. (orig.) [de

  6. Spacer geometry and particle deposition in spiral wound membrane feed channels

    KAUST Repository

    Radu, A.I.

    2014-11-01

    Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nanofiltration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic observations in membrane fouling simulators revealed formation of specific particle deposition patterns for different diamond and ladder feed spacer orientations. A three-dimensional numerical model combining fluid flow with a Lagrangian approach for particle trajectory calculations could describe very well the in-situ observations on particle deposition in flow cells. Feed spacer geometry, positioning and cross-flow velocity sensitively influenced the particle transport and deposition patterns. The deposition patterns were not influenced by permeate production. This combined experimental-modeling approach could be used for feed spacer geometry optimization studies for reduced (bio)fouling. © 2014 Elsevier Ltd.

  7. The Effect of Using Sewage Sludge Ash with and without Nano Silica Particles on Properties of Self-compacting Cement Based Materials

    Directory of Open Access Journals (Sweden)

    Amin Khoshravesh

    2014-10-01

    Full Text Available Nowadays using pozzolanic materials is crucial as a replacement of needed cement, improving properties of cement based materials and saving costs. On the other hand sewage sludge is harmful to the environment and human health. So in this research the sewage sludge ash has been used as an artificial pozzolan to produce self compacting cement based materials which could be evaluated as a revolution in the concrete industry. The objective of this research was to accelerate the performance of sewage sludge ash by utilizing nano silica particles. This research includes 10 mix designs for self compacting mortar and concrete made up of binary and ternary cementitious blends of sewage sludge ash (0%,5%,10%,15%,20% and nano silica (0%,1%. The results showed that by adding the sewage sludge ash, rheological and mechanical properties of the samples were reduced and for small percentages of sewage sludge ash, the durability characteristics were improved. The results also showed that adding nano silica improved the mechanical and durability properties of self compacting mortar and concrete. Finally in presence of nano silica, the reactivity of the sewage sludge ash was increased and its performance was improved.

  8. Long-range volcanic ash transport and fallout during the 2008 eruption of Chaiten volcano, Chile

    Science.gov (United States)

    Durant, A. J.; Prata, A. J.; Villarosa, G.; Rose, W. I.; Delmelle, P.; Viramonte, J.

    2012-04-01

    The May 2008 eruption of Chaitén volcano, Chile, provided a rare opportunity to measure the long-range transport of volcanic emissions and characteristics of a widely-dispersed terrestrial ash deposit. Airborne ash mass, quantified using thermal infrared satellite remote sensing, ranged between 0.2-0.4 Tg during the period 3-7 May 2008. A high level of spatiotemporal correspondence was observed between cloud trajectories and changes in surface reflectivity, which was inferred to indicate ash deposition. The evolution of the deposit was mapped for the first time using satellite-based observations of surface reflectivity. The distal (>80 km) ash deposit was poorly sorted and fine grained, and mean particle size varied very little beyond a distance >300 km. There were 3 consistent particle size subpopulations in fallout at distances >300 km which suggests that aggregation influenced particle settling. Discrete temporal sampling and characterisation of fallout demonstrated contributions from specific eruptive phases. Some evidence for winnowing was identified through comparison of samples collected at the time of deposition to bulk samples collected months after deposition. X-Ray Photoelectron Spectroscopy (XPS) analyses revealed surface enrichments in Ca, Na and Fe and the presence of coatings of mixed Ca-, Na- and Fe-rich salts on ash particles prior to deposition. XPS analyses revealed strong surface Fe enrichments (in contrast to the results from bulk leachate analyses), which indicates that surface analysis techniques should be applied to investigate potential influences on ocean productivity in response to volcanic ash fallout over oceans. Low S:Cl ratios in leachates indicate that the eruption had a low S content, and high Cl:F ratios imply gas-ash interaction within a Cl-rich environment. We estimate that ash fallout had potential to scavenge ~42 % of total S released into the atmosphere prior to deposition.

  9. Application of dry separative methods for decreasing content the residues unburned coal and separation Fe from black coal flies ash

    Directory of Open Access Journals (Sweden)

    František Kaľavský

    2008-06-01

    Full Text Available Main obstacle using of fly ashes in building, that is its main consumer, is the residue of unburned coal; it is expressed of loss onignition - LOI. In present, the valid STN and EU standard limits the content of LOI to 3 – 5 %, in national conditions maximum 7 %.Application of processing technologies also has to assure utilization of fly ash that provides a possibility of complex utilizationof individual products obtained by modification.By means of corona separation, based on different conductivity of individual fly ash elements, it is possible to separate unburnedcoal particles. The fly ash sample from black coal burning in melting boiler that was deposited on fly ash deposit, content of LOIof dielectric particle 6,45 % at 61 % weight yield was achieved. In the samples taken from dry taking of fly ash the non-conductingproduct contained 7,72 % of LOI at 73 % of weight yield.

  10. Advanced characterisation of municipal solid waste ashes

    Energy Technology Data Exchange (ETDEWEB)

    Skytte Pedersen, Randi

    2002-12-15

    This report deals with characterisation of Municipal Solid Waste (MSW) ashes from the Danish power plant Maebjergvaerket, Holstebro. MSW has been used as a fuel since the mid 1960's and since then, the MSW incineration plants have experienced operational problems due to deposit formation and corrosion. Inorganic elements tightly or loosely bound in the waste are the main cause of these problems. The tightly bound elements will mainly stay on the grate during combustion, whereas the loosely bound elements are volatilised and recondensed elsewhere in the furnace. Many of the heavy metals form volatile chlorides during the incineration, and the fly ash fraction thus show enrichment in these elements. Presence of chlorides and heavy metals in deposits may cause severe corrosion due to formation of low-melting eutectics. Chlorine gas in the flue gas is also of major concern with respect to corrosion, due to formation of volatile chlorides when chlorine comes in contact with the tube material. Four different ash fractions (bottom ash, super heater ash, economiser ash and fly ash) taken from Maebjergvaerket have been analysed with respect to particle sizes, structures, shapes and composition. The applied methods were scanning electron microscopy (SEM), energy dispersive X-ray analyses (EDX) and mapping, which were used in order to determine sizes, chemical composition and structure of the particles. X-ray powder diffraction (XRD) was used to provide information about crystallography and mineral phases. Chemical analysis was also performed along with a particle size distribution for the fine-grained fractions (economiser and fly ash). The amount of silicates consisting of Ca, Al and Si, were found to decrease through the furnace, whereas the amount of alkali (Na, K) chlorides and heavy metals (Pb, Zn) increased. The bonding in the waste before incineration is the direct cause of this, since silicates are tightly bound and chlorides are loosely bound. There was a

  11. Mathematical modelling of water and gas transport in layered soil covers for coal ash deposits

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, A; Lindgren, M [Kemakta Consultants Co, Stockholm (SE)

    1990-12-17

    In the present work the dry deposition alternative is investigated. In particular the design of soil covers is treated theoretically using mathematical models. The soil cover should primarily act as a barrier against infiltrating water. This is done by having soil cover materials with low permeabilities and sloping covers thereby diverting the infiltrating water in the lateral direction. An important design aspect is that overflow should be avoided since this may cause erosional problems. Thus the design of the cover should allow for lateral water flow within the cover. In the present work we use the computer code TRUST for calculating the flow rates and the moisture contents in two layer covers (till on top of clay) for varying conditions. The calculations so far show that the hydraulic conductivity of the clay layer should be smaller than 10{sup -8} m/s. However, for the simulated longer covers (50 m) a lower hydraulic conductivity gives overflow indicating that better lateral drainage must be provided for. This can be done by increasing the thickness or hydraulic conductivity of the till layer. Simulations for different slopes give little impact, while the hydraulic conductivity of the clay layer is of major importance. Gas transport through the soil cover may be of importance if the waste contains pyrite. In the presence of oxygen and water, pyrite is oxidized producing sulphuric acid. The lowered pH will accelerate the leaching of several heavy metals. The transport rate of gas through a porous material is very sensitive to the water content, decreasing rapidly with increasing water content. In the present work a model, where the unsaturated conditions are accounted for, is outlined. A previously developed method for calculating oxygen transport and oxidation rate of pyrite in connection with mine wastes is generalized from 1D to 2D. A sample calculation illustrates the feasibility of the method. (au) (43 refs.).

  12. Study on particle deposition in vertical square ventilation duct flows by different models

    International Nuclear Information System (INIS)

    Zhang Jinping; Li Angui

    2008-01-01

    A proper representation of the air flow in a ventilation duct is crucial for adequate prediction of the deposition velocity of particles. In this paper, the mean turbulent air flow fields are predicted by two different numerical models (the Reynolds stress transport model (RSM) and the realizable k-εmodel). Contours of mean streamwise velocity deduced from the k-ε model are compared with those obtained from the Reynolds stress transport model. Dimensionless deposition velocities of particles in downward and upward ventilation duct flows are also compared based on the flow fields presented by the two different numerical models. Trajectories of the particles are tracked using a one way coupling Lagrangian eddy-particle interaction model. Thousands of individual particles are released in the represented flow, and dimensionless deposition velocities are evaluated for the vertical walls in fully developed smooth vertical downward and upward square duct flows generated by the RSM and realizable k-ε model. The effects of particle diameter, dimensionless relaxation time, flow direction and air speed in vertical upward and downward square duct flows on the particle deposition velocities are discussed. The effects of lift and gravity on the particle deposition velocities are evaluated in vertical flows presented by the RSM. It is shown that the particle deposition velocities based on the RSM and realizable k-εmodel have subtle differences. The flow direction and the lift force significantly affect the particle deposition velocities in vertical duct flows. The simulation results are compared with earlier experimental data and the numerical results for fully developed duct flows. It is shown that the deposition velocities predicted are in agreement with the experimental data and the numerical results

  13. Studies of Physicochemical Processes in Atmospheric Particles and Acid Deposition.

    Science.gov (United States)

    Pandis, Spyros N.

    A comprehensive chemical mechanism for aqueous -phase atmospheric chemistry was developed and its detailed sensitivity analysis was performed. The main aqueous-phase reaction pathways for the system are the oxidation of S(IV) to S(VI) by H_2O_2 , OH, O_2 (catalysed by Fe ^{3+} and Mn^ {2+}), O_3 and HSO_sp{5}{-}. The gas-phase concentrations of SO_2, H_2O_2, HO _2, OH, O_3 HCHO, NH_3, HNO_3 and HCl and the liquid water content of the cloud are of primary importance. The Lagrangian model predictions for temperature profile, fog development, liquid water content, gas-phase concentrations of SO_2 , HNO_3, and NH_3 , pH, aqueous-phase concentrations of SO _sp{4}{2-}, NH _sp{4}{+} and NO _sp{3}{-}, and finally deposition rates of the above ions match well the observed values. A third model was developed to study the distribution of acidity and solute concentration among the various droplet sizes in a fog or a cloud. Significant solute concentration differences can occur in aqueous droplets inside a fog or a cloud. Fogs in polluted environments have the potential to increase aerosol sulfate concentrations, but at the same time to cause reductions in the aerosol concentration of nitrate, chloride, ammonium and sodium as well as in the total aerosol mass concentration. The sulfate producd during fog episodes favors the aerosol particles that have access to most of the fog liquid water. Aerosol scavenging efficiencies of around 80% were calculated for urban fogs. Sampling and subsequent mixing of fog droplets of different sizes may result in measured concentrations that are not fully representative of the fogwater chemical composition. Isoprene and beta-pinene, at concentration levels ranging from a few ppb to a few ppm were reacted photochemically with NO_ {x} in the Caltech outdoor smog chamber facility. Aerosol formation from the isoprene photooxidation was found to be negligible even under extreme ambient conditions due to the relatively high vapor pressure of its

  14. Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Georgiou, E.P.; Tsopani, A.; Piperi, L. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece)

    2011-03-15

    Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

  15. Re-burning of ash in grate boilers; Omfoerbraenning av askor i rosterpannor

    Energy Technology Data Exchange (ETDEWEB)

    Bergqvist, Kristina; Myringer, Aase; Nordgren, Daniel; Rydberg, Stina [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2005-03-01

    High contents of unburnt carbon in ashes that are dumped or recycled, is questionable from both an economical and an environmental point of view. The content of unburnt carbon in bottom and fly ash from grate boilers varies greatly between different plants but can sometimes exceed 50 %. Re-burning of ash that is separated before a final dust separation, is a relatively cheep and simple method for reducing the content of unburnt carbon in ash, which both reduces the fuel cost and the deposit cost, i.e. the cost of landfilling or recycling. As from 2005 it is prohibited to deposit ash with a too high content of unburnt organic material; the content is limited to 18 weight % of unburnt carbon. The study was carried out in two phases. The aim of the first phase was to map the different techniques used for re-burning ash that are used in grate boilers today. The mapping was done through telephone interviews and comprises technical descriptions of the systems, gathering of operational know-how, installations costs and the effect of the systems on the amount of ash generated at the plants and the content of unburnt carbon in the ash. In order to accomplish a deeper technical and economical evaluation of ash re-burning systems, the second phase involved field studies at two plants. In addition screening tests were done to investigate the connection between the content of unburnt carbon and particle size. The potential of reducing the amount of circulated inorganic material by sieving the ash before bringing it back to the furnace could thereby be determined. 13 plants that utilize re-burning of ash were identified, of which two plants re-burn the bottom ash that floats up to the surface in the wet ash removal system. The remaining 11 plants re-burn fly ash. At three plants the fly ash is first separated in a mesh sieve or similar equipment and only the coarser fly ash is re-burnt. As the amount of bottom ash that surfaces in the wet ash-removal is relatively small

  16. Deposition of biomass combustion aerosol particles in the human respiratory tract.

    Science.gov (United States)

    Löndahl, Jakob; Pagels, Joakim; Boman, Christoffer; Swietlicki, Erik; Massling, Andreas; Rissler, Jenny; Blomberg, Anders; Bohgard, Mats; Sandström, Thomas

    2008-08-01

    Smoke from biomass combustion has been identified as a major environmental risk factor associated with adverse health effects globally. Deposition of the smoke particles in the lungs is a crucial factor for toxicological effects, but has not previously been studied experimentally. We investigated the size-dependent respiratory-tract deposition of aerosol particles from wood combustion in humans. Two combustion conditions were studied in a wood pellet burner: efficient ("complete") combustion and low-temperature (incomplete) combustion simulating "wood smoke." The size-dependent deposition fraction of 15-to 680-nm particles was measured for 10 healthy subjects with a novel setup. Both aerosols were extensively characterized with regard to chemical and physical particle properties. The deposition was additionally estimated with the ICRP model, modified for the determined aerosol properties, in order to validate the experiments and allow a generalization of the results. The measured total deposited fraction of particles from both efficient combustion and low-temperature combustion was 0.21-0.24 by number, surface, and mass. The deposition behavior can be explained by the size distributions of the particles and by their ability to grow by water uptake in the lungs, where the relative humidity is close to saturation. The experiments were in basic agreement with the model calculations. Our findings illustrate: (1) that particles from biomass combustion obtain a size in the respiratory tract at which the deposition probability is close to its minimum, (2) that particle water absorption has substantial impact on deposition, and (3) that deposition is markedly influenced by individual factors.

  17. Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

    DEFF Research Database (Denmark)

    Hansen, Stine Broholm; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2017-01-01

    used to describe the deposit formation rates and deposit chemistry observed in a series of entrained flow reactor (EFR) experiments using straw and wood as fuels. It was found that model #1 was not able to describe the observed influence of temperature on the deposit buildup rates, predicting a much...... differ in the description of the sticking probability of impacted particles: model #1 employs a reference viscosity in the description of the sticking probability, while model #2 combines impaction of viscoelastic particles on a solid surface with particle capture by a viscous surface. Both models were...

  18. Lattice-Boltzmann Method with Dynamic Grid Refinement for Simulating Particle Deposition on a Single Fibre

    Directory of Open Access Journals (Sweden)

    Helmut Schomburg

    2013-03-01

    Full Text Available In this work a numerical approach to predict the deposition behaviour of nano-scale particles on the surface of a single fibre by resolving the resulting dendrite-like particle structures in detail is presented. The gas flow simulation is carried out by a two-dimensional Lattice-Boltzmann method, which is coupled with a Lagrangian approach for the particle motion. To decrease calculation time and system requirements the Lattice-Boltzmann model is extended to allow for local grid refinement. Because of the a priori unknown location of deposition, the simulation procedure starts on a coarse mesh which is then locally refined in a fully adaptive way in regions of accumulated particles. After each deposition the fluid flow is recalculated in order to resolve the coupling of the flow with the growing particle structures correctly. For the purpose of avoiding unphysical blocking of flow by growing particle dendrites the Lattice-Boltzmann method is extended to permeable cells in these regions using the Brinkmann equation. This extended deposition model is compared to simpler approaches, where the deposit has no retroaction on the flow or is treated as a solid structure. It is clear that the permeable model is most realistic and allows considering the particle deposition on a fibre as two-dimensional problem. Comprehensive simulations were conducted for analysing the importance of different parameters, i.e. free-stream velocity and particle diameter on the deposit structure. The results of this sensitivity analysis agree qualitatively well with former published numerical and experimental results. Finally the structure of the particle deposit was quantitatively characterised by using a modified fractal dimension.

  19. Properties of the fly ash from the Power Plant Dětmarovice from the point of view of their deposition in underground mines

    Directory of Open Access Journals (Sweden)

    Dirner Vojtech

    2001-06-01

    Full Text Available Mining for the Purposes of Disposal – Facilities, Requirements and Conceptions. Mining for the purposes of disposal can be instrumental in environmental protection in the future. Therefore the utilization of residues in the mining process has to be put into the foreground, whether they are a product of the mining activity itself or coming from other sources. It is possible to use the residual products as filling or building materials. Within the constantly increasing demand for building materials in the mines it is possible to combine the advantages that improve mine safety, rock mechanics and support with the secure long-term sealing of mineralized industrial residues in the lithosphere. Also the disposal of polluted, water-soluble and toxic or radioactive waste in a suitable geological formation underground can be realized ensuring long-term safety. This long-term safety is guaranteed by a multiple system of geological and technical barriers. The storage can b conducted in appropriate void space like chambers, caverns, drifts or boreholes with or without the opinion of retarding the material.Contribution is discussing the possibility of the deposition on fly ash produced by thermal power plants which are using low-grade brown coal as a fuel. Properties of fly ash were studied id detail on samples from Power Plant Dìtmarovice, northern Moravia.Results proved that fly ash can be deposited safely in underground.

  20. The deposition of magnetite particles from high velocity water onto isothermal tubes

    International Nuclear Information System (INIS)

    Burrill, K.A.

    1977-02-01

    The deposition rate of magnetite particles from a high velocity water slurry onto isothermal metal tubes was measured. The effects of velocity (5 to 100 m/s), slurry concentration (200 to 1000 mg Fe/kg H 2 O), temperature (25 to 90 deg C), pH (4 to 10 at 25 deg C), and tube material (nickel, Zircaloy-4) on deposition rate were studied. The data are interpreteω in terms of two steps in series for deposition: a mass transfer step followed by a deposition or ''inertial coasting'' step. Mass transfer of particles through the bulk water phase apparently limits the deposition of particles at high Reynolds number (10 5 ). (author)

  1. Particle migration leads to deposition-free fractionation

    NARCIS (Netherlands)

    Dinther, van A.M.C.; Schroën, C.G.P.H.; Boom, R.M.

    2013-01-01

    In membrane filtration, theporesizeofthemembranedeterminesthesizeof ‘particles’ that shouldbe rejected,leading to accumulation of particles on the membrane surface and changed particle retention in time.A process without accumulation and thereby constant retention as function of time would be well

  2. DIGESTIVE BIOAVAILABILITY TO A DEPOSIT FEDDER (ARENICOLA MARINA) OF POLYCYCLIC AROMATIC HYDROCARBONS ASSOCIATED WITH ANTHRPOGENIC PARTICLES

    Science.gov (United States)

    Marine sediments around urban areas serve as catch basins for anthropogenic particles containing polycyclic aromatic hydrocarbons (PAHs). Using incubations with gut fluids extracted from a deposit-feeding polychaete (Arenicola marina), we determined the digestive bioavailability ...

  3. Effect of fuel type and deposition surface temperature on the growth and structure of ash deposit collected during co-firing of coal with sewage-sludge, saw-dust and refuse derived fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kupka, Tomasz; Zajac, Krzysztof; Weber, Roman [Clausthal Univ. of Technology, Clausthal-Zellerfeld (Germany). Inst. of Energy Process Engineering and Fuel Technology

    2008-07-01

    Blends of a South African bituminous ''Middleburg'' coal and three alternative fuels (a municipal sewage-sludge, a saw-dust and a refuse derived fuel) have been fired in the slagging reactor to examine the effect of the added fuel on slagging propensity of the mixtures. Two kinds of deposition probes have been used, un-cooled ceramic probes and air-cooled steal probes. Distinct differences in physical and chemical structures of the deposits collected using the un-cooled ceramic probes and air-cooled metal probes have been observed. Glassy, easily molten deposits collected on un-cooled ceramic deposition probes were characteristic for co-firing of municipal sewage-sludge with coal. Porous, sintered (not molten) but easily removable deposits of the same fuel blend have been collected on the air-cooled metal deposition probes. Loose, easy removable deposits have been sampled on air-cooled metal deposition probe during co-firing of coal/saw-dust blends. The mass of the deposit sampled at lower surface temperatures (550-700 C) was always larger than the mass sampled at higher temperatures (1100-1300 C) since the higher temperature ash agglomerated and sintered much faster than the low temperature deposit. (orig.)

  4. Effect of wear parameters on dry sliding behavior of Fly Ash/SiC particles reinforced AA 2024 hybrid composites

    Science.gov (United States)

    Bhaskar Kurapati, Vijaya; Kommineni, Ravindra

    2017-09-01

    In the present work AA 2024 alloy reinforced with mixtures of SiC and Fly Ash (FA) particles of 70 µm (5, 10 and 15 wt. %) are fabricated using the stir casting method. Both reinforcements are added in equal weight proportions. The wear test specimens are prepared from both the alloy and composite castings in the dimensions of Ф 4 mm and 30 mm lengths by the wire cut EDM process. The dry sliding wear properties of the prepared composites at room temperature are estimated by pin-on-disc wear testing equipment. The wear characteristics of the composites are studied by conducting the dry sliding wear test over loads of 0.5 Kgf, 1.0 Kgf, 1.5 Kgf, a track diameter of 60 mm and sliding times of 15 min, 30 min, 45min. The experimental results shows that the wear decreases with an increase in the weight percentage of FA and SiC particles in the matrix. Additionally wear increases with an increase in load and sliding time. Further, it is found that the wear resistance of the AA2024-Hybrid composites is higher than that of the AA2024 matrix.

  5. Research on sludge-fly ash ceramic particles (SFCP) for synthetic and municipal wastewater treatment in biological aerated filter (BAF).

    Science.gov (United States)

    Zhao, Yaqin; Yue, Qinyan; Li, Renbo; Yue, Min; Han, Shuxin; Gao, Baoyu; Li, Qian; Yu, Hui

    2009-11-01

    Sludge-fly ash ceramic particles (SFCP) and clay ceramic particles (CCP) were employed in two lab-scale up-flow biological aerated filters (BAF) for wastewater treatment to investigate the availability of SFCP used as biofilm support compared with CCP. For synthetic wastewater, under the selected hydraulic retention times (HRT) of 1.5, 0.75 and 0.37 h, respectively, the removal efficiencies of chemical oxygen demand (COD(Cr)) and ammonium nitrogen (NH(4)(+)-N) in SFCP reactor were all higher than those of CCP reactor all through the media height. Moreover, better capabilities responding to loading shock and faster recovery after short intermittence were observed in the SFCP reactor compared with the CCP reactor. For municipal wastewater treatment, which was carried out under HRT of 0.75 h, air-liquid ratio of 7.5 and backwashing period of 48 h, the SFCP reactor also performed better than the CCP reactor, especially for the removal of NH(4)(+)-N.

  6. Jurassic ash-flow sheets, calderas, and related intrusions of the Cordilleran volcanic arc in southeastern Arizona: implications for regional tectonics and ore deposits

    Science.gov (United States)

    Lipman, P.W.; Hagstrum, J.T.

    1992-01-01

    Volcanologic, petrologic, and paleomagnetic studies of widespread Jurassic ash-flow sheets in the Huachuca-southern Dragoon Mountains area have led to identification of four large source calderas and associated comagnetic intracaldera intrusions. Stratigraphic, facies, and contact features of the caldera-related tuffs also provide constraints on the locations, lateral displacements, and very existence for some major northwest-trending faults and inferred regional thrusts in southeastern Arizona. Silicic alkalic compositions of the Jurassic caldera-related, ash-flow tuffs; bimodal associated mafic magmatism; and interstratified coarse sedimentary deposits provide evidence for synvolcanic extension and rifting within the Cordilleran magmatic arc. Gold-copper mineralization is associated with subvolcanic intrusions at several of the Jurassic calderas. -from Authors

  7. Feasibility study of electrophoresis deposition of DyF3 on Nd-Fe-B particles for coercivity enhancement

    Directory of Open Access Journals (Sweden)

    K. M. Kim

    2018-05-01

    Full Text Available Feasibility of the electrophoresis deposition (EPD technique for homogeneous and adhesive deposition of DyF3 particles on the Nd-Fe-B-type particles was studied, and coercivity enhancement in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD was investigated. HDDR-treated Nd12.5Fe80.6B6.4Ga0.3Nb0.2 particles were deposited with DyF3 particles by EPD. More homogeneous and adhesive deposition of DyF3 particles on the surface of Nd-Fe-B particles was made by the EPD with respect to conventional dip-coating, and this led to more active and homogeneous diffusion of Dy. More profound coercivity enhancement was achieved in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD compared to dip-coated particles.

  8. Feasibility study of electrophoresis deposition of DyF3 on Nd-Fe-B particles for coercivity enhancement

    Science.gov (United States)

    Kim, K. M.; Kang, M. S.; Kwon, H. W.; Lee, J. G.; Yu, J. H.

    2018-05-01

    Feasibility of the electrophoresis deposition (EPD) technique for homogeneous and adhesive deposition of DyF3 particles on the Nd-Fe-B-type particles was studied, and coercivity enhancement in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD was investigated. HDDR-treated Nd12.5Fe80.6B6.4Ga0.3Nb0.2 particles were deposited with DyF3 particles by EPD. More homogeneous and adhesive deposition of DyF3 particles on the surface of Nd-Fe-B particles was made by the EPD with respect to conventional dip-coating, and this led to more active and homogeneous diffusion of Dy. More profound coercivity enhancement was achieved in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD compared to dip-coated particles.

  9. Deposition of cigarette smoke particles in the rat respiratory tract

    International Nuclear Information System (INIS)

    Chen, B.T.; Weber, R.E.; Yeh, H.C.; Lundgren, D.L.; Snipes, M.B.; Mauderly, J.L.

    1988-01-01

    Male and female rats were exposed to mainstream cigarette smoke to determine the fractional deposition. Deposition studies were conducted by placing the rats in plethysmography tubes for respiratory minute volume measurements and exposing them to 14 C-dotriacontane-labeled cigarette smoke at mass concentrations of 202 or 624 mg/m 3 for 25 min. Immediately after the exposure, the rats were sacrificed and the 14 C contents in various tissues and organs were analyzed. Results showed that the GI tract contained 16-31% of the total activity, indicating significant clearance from the large airways and nose to the GI tract during the exposure and during the 10-15 min between cessation of the exposure and the removal of the organs. Total deposition of the inhaled activity was 20.1 ± 1.6% for both exposure concentrations. The intrapulmonary deposition fractions (lung lobes plus airways below the lobar bronchi) were 12.4 ± 0.9% and 15.9 ± 1.4% for high and low concentrations, respectively, suggesting a slight enhancement in upper airway deposition for animals exposed to the higher smoke concentration. (author)

  10. Deposition of cigarette smoke particles in the rat respiratory tract

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B T; Weber, R E; Yeh, H C; Lundgren, D L; Snipes, M B; Mauderly, J L

    1988-12-01

    Male and female rats were exposed to mainstream cigarette smoke to determine the fractional deposition. Deposition studies were conducted by placing the rats in plethysmography tubes for respiratory minute volume measurements and exposing them to {sup 14}C-dotriacontane-labeled cigarette smoke at mass concentrations of 202 or 624 mg/m{sup 3} for 25 min. Immediately after the exposure, the rats were sacrificed and the 14{sub C} contents in various tissues and organs were analyzed. Results showed that the GI tract contained 16-31% of the total activity, indicating significant clearance from the large airways and nose to the GI tract during the exposure and during the 10-15 min between cessation of the exposure and the removal of the organs. Total deposition of the inhaled activity was 20.1 {+-} 1.6% for both exposure concentrations. The intrapulmonary deposition fractions (lung lobes plus airways below the lobar bronchi) were 12.4 {+-} 0.9% and 15.9 {+-} 1.4% for high and low concentrations, respectively, suggesting a slight enhancement in upper airway deposition for animals exposed to the higher smoke concentration. (author)

  11. Measurement of natural activity in peat ashes

    International Nuclear Information System (INIS)

    Suomela, J.

    1985-01-01

    High proportions of radioactive materials in peat ashes may involve radiation hazards during handling and deposition of these waste materials. Measurements have been performed to determine the content of radioactive materials in ashes from peat burning. The activities in fly ash and ''solid'' ash in seven peat-fired power plants in Sweden are presented. The methods of analysing and measuring peat ashes for activity from different radionuclides are described. The activity levels in ash samples are given

  12. Fly ash aggregates. Vliegaskunstgrind

    Energy Technology Data Exchange (ETDEWEB)

    1983-03-01

    A study has been carried out into artificial aggregates made from fly ash, 'fly ash aggregates'. Attention has been drawn to the production of fly ash aggregates in the Netherlands as a way to obviate the need of disposal of fly ash. Typical process steps for the manufacturing of fly ash aggregates are the agglomeration and the bonding of fly ash particles. Agglomeration techniques are subdivided into agitation and compaction, bonding methods into sintering, hydrothermal and 'cold' bonding. In sintering no bonding agent is used. The fly ash particles are more or less welded together. Sintering in general is performed at a temperature higher than 900 deg C. In hydrothermal processes lime reacts with fly ash to a crystalline hydrate at temperatures between 100 and 250 deg C at saturated steam pressure. As a lime source not only lime as such, but also portland cement can be used. Cold bonding processes rely on reaction of fly ash with lime or cement at temperatures between 0 and 100 deg C. The pozzolanic properties of fly ash are used. Where cement is applied, this bonding agent itself contributes also to the strength development of the artificial aggregate. Besides the use of lime and cement, several processes are known which make use of lime containing wastes such as spray dry absorption desulfurization residues or fluid bed coal combustion residues. (In Dutch)

  13. Analysis of the 2006 block-and-ash flow deposits of Merapi Volcano, Java, Indonesia, using high-spatial resolution IKONOS images and complementary ground based observations

    Science.gov (United States)

    Thouret, Jean-Claude; Gupta, Avijit; Liew, Soo Chin; Lube, Gert; Cronin, Shane J.; Surono, Dr

    2010-05-01

    On 16 June 2006 an overpass of IKONOS coincided with the emplacement of an active block-and-ash flow fed by a lava dome collapse event at Merapi Volcano (Java, Indonesia). This was the first satellite image recorded for a moving pyroclastic flow. The very high-spatial resolution data displayed the extent and impact of the pyroclastic deposits emplaced during and prior to, the day of image acquisition. This allowed a number of features associated with high-hazard block-and-ash flows emplaced in narrow, deep gorges to be mapped, interpreted and understood. The block-and-ash flow and surge deposits recognized in the Ikonos images include: (1) several channel-confined flow lobes and tongues in the box-shaped valley; (2) thin ash-cloud surge deposit and knocked-down trees in constricted areas on both slopes of the gorge; (3) fan-like over bank deposits on the Gendol-Tlogo interfluves from which flows were re-routed in the Tlogo secondary valley; (4) massive over bank lobes on the right bank from which flows devastated the village of Kaliadem 0.5 km from the main channel, a small part of this flow being re-channeled in the Opak secondary valley. The high-resolution IKONOS images also helped us to identify geomorphic obstacles that enabled flows to ramp and spill out from the sinuous channel, a process called flow avulsion. Importantly, the avulsion redirected flows to unexpected areas away from the main channel. In the case of Merapi we see that the presence of valley fill by previous deposits, bends and man-made dams influence the otherwise valley-guided course of the flows. Sadly, Sabo dams (built to ameliorate the effect of high sediment load streams) can actually cause block-and-ash flows to jump out of their containing channel and advance into sensitive areas. Very-high-spatial resolution satellite images are very useful for mapping and interpreting the distribution of freshly erupted volcanic deposits. IKONOS-type images with 1-m resolution provide opportunities to

  14. Superpermeable membrane for particle control in divertor: the effect of impurity deposition

    International Nuclear Information System (INIS)

    Nakahara, Y.; Nakamura, Y.; Ohyabu, N.; Suzuki, H.; Busnyuk, A.; Alimov, V.

    2000-01-01

    The effect of impurity (stainless steel (SS) components, carbon) deposition onto niobium membrane surface on the membrane permeability to hydrogen particles is investigated with a plasma device. The deposition of SS components onto the upstream surface of the membrane at the membrane temperature (T M ) M M ≥800 deg. C. It appears to be due to the dissolution of the impurities deposited onto the upstream surface into the membrane bulk within the measurements

  15. Deposition of particles and iodine to outdoor surfaces and in the respiratory tract

    International Nuclear Information System (INIS)

    Garland, J.A.

    1988-01-01

    Dry deposition of particles depends strongly on particle size, and is also influenced by the geometry of the surface and weather parameters. Precipitation scavenging is also influenced to some degree by particle size, but hygroscopic properties of soluble particles are also likely to enhance deposition in precipitation. Similar comments apply in the respiratory tract, where particle size and solubility may influence the extent and site of deposition: the site is important for insoluble particles at least since it determines retention time in the body. Thus measurement of particle size and investigation of solubility would be valuable in interpreting deposition inhalation and air concentration observations. Iodine has several chemical forms in the air. It is valuable to sample in such a way that different forms are partitioned, although there is some uncertainty in their identification. The rate of deposition to vegetation depends strongly on the chemical form of the iodine, but the vapour forms of iodine that occur in the atmosphere may all be retained efficiently on inhalation

  16. Particle and energy transport studies on TFTR and implications for helium ash in future fusion devices

    International Nuclear Information System (INIS)

    Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Bell, R.E.; Grek, B.; Hulse, R.A.; Johnson, D.W.; Hill, K.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.

    1992-01-01

    Particle and energy transport in tokamak plasmas have long been subjects of vigorous investigation. Present-day measurement techniques permit radially resolved studies of the transport of electron perturbations, low- and high-Z impurities, and energy. In addition, developments in transport theory provide tools that can be brought to bear on transport issues. Here, we examine local particle transport measurements of electrons, fully-stripped thermal helium, and helium-like iron in balanced-injection L-mode and enhanced confinement deuterium plasmas on TFTR of the same plasma current, toroidal field, and auxiliary heating power. He 2+ and Fe 24+ transport has been studied with charge exchange recombination spectroscopy, while electron transport has been studied by analyzing the perturbed electron flux following the same helium puff used for the He 2+ studies. By examining the electron and He 2+ responses following the same gas puff in the same plasmas, an unambiguous comparison of the transport of the two species has been made. The local energy transport has been examined with power balance analysis, allowing for comparisons to the local thermal fluxes. Some particle and energy transport results from the Supershot have been compared to a transport model based on a quasilinear picture of electrostatic toroidal drift-type microinstabilities. Finally, implications for future fusion reactors of the observed correlation between thermal transport and helium particle transport is discussed

  17. RANS modeling for particle transport and deposition in turbulent duct flows: Near wall model uncertainties

    International Nuclear Information System (INIS)

    Jayaraju, S.T.; Sathiah, P.; Roelofs, F.; Dehbi, A.

    2015-01-01

    Highlights: • Near-wall modeling uncertainties in the RANS particle transport and deposition are addressed in a turbulent duct flow. • Discrete Random Walk (DRW) model and Continuous Random Walk (CRW) model performances are tested. • Several near-wall anisotropic model accuracy is assessed. • Numerous sensitivity studies are performed to recommend a robust, well-validated near-wall model for accurate particle deposition predictions. - Abstract: Dust accumulation in the primary system of a (V)HTR is identified as one of the foremost concerns during a potential accident. Several numerical efforts have focused on the use of RANS methodology to better understand the complex phenomena of fluid–particle interaction at various flow conditions. In the present work, several uncertainties relating to the near-wall modeling of particle transport and deposition are addressed for the RANS approach. The validation analyses are performed in a fully developed turbulent duct flow setup. A standard k − ε turbulence model with enhanced wall treatment is used for modeling the turbulence. For the Lagrangian phase, the performance of a continuous random walk (CRW) model and a discrete random walk (DRW) model for the particle transport and deposition are assessed. For wall bounded flows, it is generally seen that accounting for near wall anisotropy is important to accurately predict particle deposition. The various near-wall correlations available in the literature are either derived from the DNS data or from the experimental data. A thorough investigation into various near-wall correlations and their applicability for accurate particle deposition predictions are assessed. The main outcome of the present work is a well validated turbulence model with optimal near-wall modeling which provides realistic particle deposition predictions

  18. Deposition of bi-dispersed particles in inkjet-printed evaporating colloidal drops

    Science.gov (United States)

    Sun, Ying; Joshi, Abhijit; Chhasatia, Viral

    2010-11-01

    In this study, the deposition behaviors of inkjet-printed evaporating colloidal drops consisting of bi-dispersed micro and nano-sized particles are investigated by fluorescence microscopy and SEM. The results on hydrophilic glass substrates show that, evaporatively-driven outward flow drives the nanoparticles to deposit close to the pinned contact line while an inner ring deposition is formed by microparticles. This size-induced particle separation is consistent with the existence of a wedge-shaped drop edge near the contact line region of an evaporating drop on a hydrophilic substrate. The replenishing evaporatively-driven flow assembles nanoparticles closer to the pinned contact line forming an outer ring of nanoparticles and this particle jamming further enhances the contact line pinning. Microparticles are observed to form an inner ring inside the nano-sized deposits. This size-induced particle separation presents a new challenge to the uniformity of functional materials in bioprinting applications where nanoparticles and micro-sized cells are mixed together. On the other hand, particle self-assembly based on their sizes provides enables easy and well-controlled pattern formation. The effects of particle size contrast, particle volume fraction, substrate surface energy, and relative humidity of the printing environment on particle separation are examined in detail.

  19. Experimental studies on particle deposition by thermophoresis and inertial impaction from particulate high temperature gas flow

    International Nuclear Information System (INIS)

    Kim, S.S.; Kim, Y.J.

    1987-01-01

    In view of fouling and erosion of gas turbine blade, heat exchanger and pipelines, increasing attention has been paid to particle deposition (transport) in high temperature flow systems. This is also necessary to develop a cleaning or filtration devices. Using 'real time' laser-light reflectivity and scanning electron microscope technique, we quantitatively treat particle size effect and the interaction between Brownian diffusion, thermoporesis (particle drift down a temperature gradient), and inertial impaction of particles (0.2 to 30 μm in diameter) in laminar hot combustion gas-particles flow (ca. 1565 K)

  20. Source contributions to airborne particle deposition at the Yungang Grottoes, China

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, Lynn G.; Christoforou, Christos S.; Gerk, Timothy J.; Cass, Glen R. [Environmental Engineering Science Department and Environmental Quality Laboratory, California Institute of Technology Pasadena, CA (United States); Casuccio, Gary S.; Cooke, Gary A.; Leger, Michael [R.J. Lee Group, Inc., Monroeville, PA (United States); Olmez, Ilhan [Nuclear Reactor Laboratory, Massachusetts Institute of Technology Cambridge, MA (United States)

    1995-04-28

    The Buddhist cave temple complex at Yungang in northern China is affected by a rapid accumulation of airborne particles that settle onto the thousands of statues contained within those caves. Experiments have been conducted to identify the most important air pollution sources that contribute to the dust deposition problem. The spatial distribution of the deposition rate of airborne particles within a 2 km x 2 km area surrounding the grottoes was measured during a 2-day period in April, 1991. Peak particle deposition rates of >60 {mu}g m{sup -2} s{sup -1} were found at locations within the village of Yungang itself and along the adjacent coal-haul highway. Moving away from the village and coal-haul highway, deposition rates decline to much lower values, indicating that the village and highway are significant sources of airborne particles. A comparison of the mineralogical composition of the dust deposits in the caves with the composition of local soil dust, paved road dust from the coal-haul highway and deteriorated cave ceiling rock material indicates that the dust deposits in the caves are a combination of the above sources, with the paved road dust from the coal-haul highway providing the closest match to the largest quantity of the material deposited in the caves

  1. In vitro and in vivo lung deposition of coated magnetic aerosol particles.

    Science.gov (United States)

    Xie, Yuanyuan; Longest, P Worth; Xu, Yun Hao; Wang, Jian Ping; Wiedmann, Timothy Scott

    2010-11-01

    The magnetic induced deposition of polydispersed aerosols composed of agglomerated superparamagnetic particles was measured with an in vitro model system and in the mouse trachea and deep lung for the purpose of investigating the potential of site specific respiratory drug delivery. Oleic acid coated superparamagnetic particles were prepared and characterized by TEM, induced magnetic moment, and iron content. The particles were dispersed in cyclohexane, aerosolized with an ultrasonic atomizer and dried by sequential reflux and charcoal columns. The fraction of iron deposited on glass tubes increased with particle size and decreasing flow rate. High deposition occurred with a small diameter tube, but the deposition fraction was largely independent of tube size at larger diameters. Results from computational fluid dynamics qualitatively agreed with the experimental results. Enhanced deposition was observed in the mouse lung but not in the trachea consistent with the analysis of the aerodynamic time allowed for deposition and required magnetic deposition time. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

  2. Lateral particle density reconstruction from the energy deposits of particles in the KASCADE-Grande detector stations

    International Nuclear Information System (INIS)

    Toma, G.; Brancus, I.M.; Mitrica, B.; Sima, O.; Rebel, H.

    2005-01-01

    The study of primary cosmic rays with energies greater than 10 14 eV is done mostly by indirect observation techniques such as the study of Extensive Air Showers (EAS). In the much larger framework effort of inferring data on the mass and energy of the primaries from EAS observables, the present study aims at delivering a versatile method and software tool that will be used to reconstruct lateral particle densities from the energy deposits of particles in the KASCADE-Grande detector stations. The study has been performed on simulated events, by taking into account the interaction of the EAS components with the detector array (energy deposits). The energy deposits have been parametrized for different incident energies and angles. Thus it is possible to reconstruct the particle densities in detectors from the energy deposits. A correlation between lateral particle density and primary mass and primary energy (at ∼ 600 m from shower core) has been established. The study puts great emphasis on the quality of reconstruction and also on the speed of the technique. The data obtained from the study on simulated events will be used soon on real events detected by the KASCADE-Grande array. (authors)

  3. Nano/micro particle beam for ceramic deposition and mechanical etching

    International Nuclear Information System (INIS)

    Chun, Doo-Man; Kim, Min-Saeng; Kim, Min-Hyeng; Ahn, Sung-Hoon; Yeo, Jun-Cheol; Lee, Caroline Sunyong

    2010-01-01

    Nano/micro particle beam (NPB) is a newly developed ceramic deposition and mechanical etching process. Additive (deposition) and subtractive (mechanical etching) processes can be realized in one manufacturing process using ceramic nano/micro particles. Nano- or micro-sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum conditions. According to the process conditions, the ceramic powder can be deposited on metal substrates without thermal damage, and mechanical etching can be conducted in the same process with a simple change of process conditions and powders. In the present work, ceramic aluminum oxide (Al 2 O 3 ) thin films were deposited on metal substrates. In addition, the glass substrate was etched using a mask to make small channels. Deposited and mechanically etched surface morphology, coating thickness and channel depth were investigated. The test results showed that the NPB provides a feasible additive and subtractive process using ceramic powders.

  4. The influence of magnetic field on the inertial deposition of a particle on a rotating disk

    International Nuclear Information System (INIS)

    Tsatsin, P O; Beskachko, V P

    2008-01-01

    The problem of inertial deposition attracts considerable attention in the connection with the separating of detrimental impurities and the refining of liquid metals. In the present investigation the deposition of particles suspended in a conducting melt on the rotating disk in the presence of axial uniform magnetic field is considered. The field of the fluid velocities is computed by means of the MHD-analogue of Karman reduction, which makes possible to reduce initial governing nonlinear partial differential equations to a two-point boundary value problem for the set of ordinary differential equations. The influence of magnetic field on dia-and paramagnetic particle deposition effect was estimated. The results reveal that magnetic field has significant effect on particle parameters, especially for magnetic particles

  5. Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

    Science.gov (United States)

    Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

    2012-09-01

    This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

  6. Airflow structures and nano-particle deposition in a human upper airway model

    Science.gov (United States)

    Zhang, Z.; Kleinstreuer, C.

    2004-07-01

    Considering a human upper airway model, or equivalently complex internal flow conduits, the transport and deposition of nano-particles in the 1-150 nm diameter range are simulated and analyzed for cyclic and steady flow conditions. Specifically, using a commercial finite-volume software with user-supplied programs as a solver, the Euler-Euler approach for the fluid-particle dynamics is employed with a low-Reynolds-number k- ω model for laminar-to-turbulent airflow and the mass transfer equation for dispersion of nano-particles or vapors. Presently, the upper respiratory system consists of two connected segments of a simplified human cast replica, i.e., the oral airways from the mouth to the trachea (Generation G0) and an upper tracheobronchial tree model of G0-G3. Experimentally validated computational fluid-particle dynamics results show the following: (i) transient effects in the oral airways appear most prominently during the decelerating phase of the inspiratory cycle; (ii) selecting matching flow rates, total deposition fractions of nano-size particles for cyclic inspiratory flow are not significantly different from those for steady flow; (iii) turbulent fluctuations which occur after the throat can persist downstream to at least Generation G3 at medium and high inspiratory flow rates (i.e., Qin⩾30 l/min) due to the enhancement of flow instabilities just upstream of the flow dividers; however, the effects of turbulent fluctuations on nano-particle deposition are quite minor in the human upper airways; (iv) deposition of nano-particles occurs to a relatively greater extent around the carinal ridges when compared to the straight tubular segments in the bronchial airways; (v) deposition distributions of nano-particles vary with airway segment, particle size, and inhalation flow rate, where the local deposition is more uniformly distributed for large-size particles (say, dp=100 nm) than for small-size particles (say, dp=1 nm); (vi) dilute 1 nm particle

  7. Effect of uncertainty in nasal airway deposition of radioactive particles on effective dose

    Energy Technology Data Exchange (ETDEWEB)

    Guilmette, R.A.; Birchall, A.; Jarvis, N.S

    1998-07-01

    In the current ICRP human respiratory tract (RT) model (ICRP Publication 66), the deposition of particles in various regions of the RT during natural breathing is modelled by considering the RT as a series of filters, resulting in deposition probabilities for distal portions of the RT being dependent on those of the proximal segments. Thus, uncertainties in regional deposition in proximal segments of the RT are reflected or propagated in uncertainties in deposition in the distal segments of the lung. Experimental data on aerosol particle deposition have demonstrated significant variability in nasal airway (NA) deposition for different individuals studied. This report summarises the impact of introducing variability in NA deposition efficiency on the calculation of effective doses using the ICRP 66 model for selected radionuclides. The computer software LUDEP, modified for this purpose, was used to customise deposition patterns, and effective doses were calculated for several radionuclides ({sup 111}In, {sup 106}Ru, {sup 60}Co, {sup 210}Po, {sup 238}U and {sup 239}Pu) chosen to represent isotopes with various decay schemes and half-lives. The results indicated significant but particle-size-specific effects of assumed NA deposition efficiencies on the calculated effective doses, which varied typically by factors of five to six. The majority of the variability was associated with direct effects on deposition patterns, but in some cases, alterations of radiation dose distribution within the various target organs also contributed to the variability. These results provide a basis for evaluating uncertainties due to inter-individual differences in deposition patterns for radiation protection and risk analysis. (author)

  8. Energy deposition and GDR emission in inelastic alpha particle scattering

    CERN Document Server

    Viesti, G; Fabris, D; Nebbia, G; Cinausero, M; Fioretto, E; Napoli, D R; Prete, G; Hagel, K; Natowitz, J B; Wada, R; Gonthier, P; Majka, Z; Alfarro, R; Zhao, Y; Mdeiwayeh, N; Ho, T

    1999-01-01

    Neutron fold distributions measured for the reaction sup 2 sup 0 sup 9 Bi(alpha,alpha') at 240 MeV have been analyzed with the help of Statistical Model calculations to determine the distribution of excitation energy in the primary target fragments as a function of the projectile energy loss, EL. Results show that the distributions in excitation energy feature a plateau which extends from the kinematical limit E sub x =EL to very small excitations, suggesting a variety of interactions of the beam particles with the target nucleus. Requiring an additional coincidence with a light charged particle leads to selection of a significant higher average excitation energy. This effect is extrapolated to explore results of previous GDR decay measurements in the case of a sup 2 sup 0 sup 8 Pb target. Corrections of derived GDR parameters due to the partial transfer of excitation energy are suggested.

  9. Clearance patterns for 111In-oxide particles deposited in specific airways of beagle dogs

    International Nuclear Information System (INIS)

    Snipes, M.B.; Muggenburg, B.A.; Griffith, W.C.; Guilmette, R.A.

    1994-01-01

    The International Commission on Radiological Protection (ICRP) has incorporated long-term retention of radioactive particles in conducting airways into its newly approved respiratory tract dosimetry model. This model is purported to provide a better basis for assessing risk associated with human inhalation exposures to radioactive particles. However, applying the new model requires an understanding of particle retention patterns in conducting airways of the lung. Studies are being conducted at ITRI to quantify long-term retention patterns for particles deposited at specific sites in conducting airways of Beagle dogs. The dog was selected as a model because long-term retention and clearance patterns for particles deposited in the lungs of dogs and humans are similar

  10. Factors controlling deposits in recovery boilers -particle formation and deposition; Soodakattilan likaantuminen ja siihen vaikuttavien tekijoeiden hallinta. Hiukkasten muodostuminen ja depositio

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E I; Mikkanen, P; Tapper, U; Ylaetalo, S; Jaervinen, R [VTT Chemical Technology, Espoo (Finland); Jokiniemi, J K; Pyykoenen, J; Eskola, A [VTT Energy, Espoo (Finland)

    1997-10-01

    In this project the aim is to find critical factors controlling the deposit formation in the recovery boilers. Focus is on particle formation, growth and deposition. During year 1995 the aerosol particle formation was studied by an experimental study within the recovery boiler furnace and by a sensitivity study with the ABC (Aerosol Behaviour in Combustion) computer code. During year 1996 the experimental studies on the aerosol particle formation continued within the furnace and the deposition mechanisms for carry over particles were included in the ABC code and sensitivity studies of the deposition were carried out. The experimental study confirmed the fact that the particles are already formed in the recovery boiler furnace. The particle formation is initiated in the boundary layer of the burning droplet or char bed, where metals are vaporised and oxidised to form tiny seed particles

  11. Rheology of fly ashes from coal and biomass co-combustion

    DEFF Research Database (Denmark)

    Arvelakis, Stelios; Frandsen, Flemming

    2010-01-01

    The presence of large amounts of alkali metals, chlorine and sulphur in most biomass fuels - compared to coal - can create serious ash-related problems such as deposition, agglomeration and/or corrosion. This paper discusses the viscosity characteristics of fly ash from the co-combustion of various...... coal/biomass blends in a pilot scale pf-boiler. The produced data provide information on the melting of the ash and its flow characteristics, as a function of temperature, which may be used to modify the temperature profile of the boiler in order to avoid slagging. Straw co-firing lowers the ash...... viscosity leading to higher stickiness of the ash particles. Wood co-firing has only minor effects, due to the composition of wood ash and the low percentage of wood in the coal/biomass blend....

  12. A two-stage treatment for Municipal Solid Waste Incineration (MSWI) bottom ash to remove agglomerated fine particles and leachable contaminants.

    Science.gov (United States)

    Alam, Qadeer; Florea, M V A; Schollbach, K; Brouwers, H J H

    2017-09-01

    In this lab study, a two-stage treatment was investigated to achieve the valorization of a municipal solid waste incineration (MSWI) bottom ash fraction below 4mm. This fraction of MSWI bottom ash (BA) is the most contaminated one, containing potentially toxic elements (Cu, Cr, Mo and Sb), chlorides and sulfates. The BA was treated for recycling by separating agglomerated fine particles (≤125µm) and soluble contaminants by using a sequence of sieving and washing. Initially, dry sieving was performed to obtain BA-S (≤125µm), BA-M (0.125-1mm) and BA-L (1-4mm) fractions from the original sample. The complete separation of fine particles cannot be achieved by conventional sieving, because they are bound in a cementitious matrix around larger BA grains. Subsequently, a washing treatment was performed to enhance the liberation of the agglomerated fine particles from the BA-M and BA-L fractions. These fine particles were found to be similar to the particles of BA-S fraction in term of chemical composition. Furthermore, the leaching behavior of Cr, Mo Sb, chlorides and sulfates was investigated using various washing parameters. The proposed treatment for the separation of agglomerated fine particles with dry sieving and washing (L/S 3, 60min) was successful in bringing the leaching of contaminants under the legal limit established by the Dutch environmental norms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Accumulation and selective maternal transfer of contaminants in the turtle Trachemys scripta associated with coal ash deposition

    Energy Technology Data Exchange (ETDEWEB)

    Nagle, R.D.; Rowe, C.L.; Congdon, J.D. [University of Georgia, Aiken, SC (USA). Savannah River Ecology Laboratory

    2001-07-01

    Coal combustion wastes are enriched in a number of potentially toxic compounds and may pose risks to biota exposed to the wastes. Slider turtles (Trachemys scripta) are common inhabitants of coal ash settling basins in South Carolina, USA, where they feed on contaminated prey items and accumulate high levels of potentially toxic compounds in their tissues. Furthermore, female sliders sometimes nest in contaminated spill piles and thus may expose embryos to contaminated soils. We examined two potential pathways by which female T. scripta may influence the survivorship and quality of their offspring in a contaminated habitat: (1) nesting in contaminated soil and (2) maternal transfer of pollutants. Eggs were collected from turtles captured in coal ash-polluted or unpolluted sites; individual clutches were incubated in both ash-contaminated and uncontaminated soil in outdoor, artificial nests. Incubation in contaminated soil was associated with reduced embryo survivorship. Adult females from the polluted site accumulated high levels of As, Cd, Cr, and Se in their tissues, yet Se was the only element transferred maternally to hatchlings at relatively high levels. Hatchlings from polluted-site females exhibited reduced O{sub 2} consumption rates compared to hatchlings from reference sites. Relatively high levels of Se transferred to hatchlings by females at the ash-polluted site might contribute to the observed differences in hatchling physiology.

  14. Pulsed laser deposition of metallic films on the surface of diamond particles for diamond saw blades

    International Nuclear Information System (INIS)

    Jiang Chao; Luo Fei; Long Hua; Hu Shaoliu; Li Bo; Wang Youqing

    2005-01-01

    Ti or Ni films have been deposited on the diamond particle surfaces by pulsed laser deposition. Compressive resistance of the uncoated and coated diamond particles was measured, respectively, in the experiments. The compressive resistance of the Ti-coated diamonds particles was found much higher than that of the uncoated ones. It increased by 39%. The surface morphology is observed by the metallography microscope. The surface of the uncoated diamonds particles had many hollows and flaws, while the surface of Ni-coated diamond particles was flat and smooth, and the surface of Ti-coated diamond particles had some metal masses that stood out of the surface of the Ti-coated film. The components of the metallic films of diamond particles were examined by X-ray diffractometry (XRD). TiC was found formed on the Ti-coated diamond surface, which resulted in increased surface bonding strength between the diamond particles and the Ti films. Meanwhile, TiC also favored improving the bonding strength between the coated diamond particles and the binding materials. Moreover, the bending resistance of the diamond saw blade made of Ti-coated diamond was drastically higher than that of other diamond saw blades, which also played an important role in improving the blade's cutting ability and lifetime. Therefore, it was most appropriate that the diamond saw blade was made of Ti-coated diamond particles rather than other materials

  15. Simulation of enhanced deposition due to magnetic field alignment of ellipsoidal particles in a lung bifurcation.

    Science.gov (United States)

    Martinez, R C; Roshchenko, A; Minev, P; Finlay, W H

    2013-02-01

    Aerosolized chemotherapy has been recognized as a potential treatment for lung cancer. The challenge of providing sufficient therapeutic effects without reaching dose-limiting toxicity levels hinders the development of aerosolized chemotherapy. This could be mitigated by increasing drug-delivery efficiency with a noninvasive drug-targeting delivery method. The purpose of this study is to use direct numerical simulations to study the resulting local enhancement of deposition due to magnetic field alignment of high aspect ratio particles. High aspect ratio particles were approximated by a rigid ellipsoid with a minor diameter of 0.5 μm and fluid particle density ratio of 1,000. Particle trajectories were calculated by solving the coupled fluid particle equations using an in-house micro-macro grid finite element algorithm based on a previously developed fictitious domain approach. Particle trajectories were simulated in a morphologically realistic geometry modeling a symmetrical terminal bronchiole bifurcation. Flow conditions were steady inspiratory air flow due to typical breathing at 18 L/min. Deposition efficiency was estimated for two different cases: [1] particles aligned with the streamlines and [2] particles with fixed angular orientation simulating the magnetic field alignment of our previous in vitro study. The local enhancement factor defined as the ratio between deposition efficiency of Case [1] and Case [2] was found to be 1.43 and 3.46 for particles with an aspect ratio of 6 and 20, respectively. Results indicate that externally forcing local alignment of high aspect ratio particles can increase local deposition considerably.

  16. Ash study for biogas purification

    International Nuclear Information System (INIS)

    Juarez V, R. I.

    2016-01-01

    This work evaluates the ashes generated from the wood and coal combustion process of the thermoelectric plant in Petacalco, Guerrero (Mexico) in order to determine its viability as a filter in the biogas purification process. The ash is constituted by particles of morphology and different chemical properties, so it required a characterization of the same by different analytical techniques: as was scanning electron microscopy and X-ray diffraction, in order to observe the microstructure and determine the elemental chemical composition of the particles. Prior to the analysis, a set of sieves was selected to classify as a function of particle size. Four different types of ashes were evaluated: one generated by the wood combustion (wood ash) and three more of the Petacalco thermoelectric generated by the coal combustion (wet fly ash, dry fly ash and dry bottom ash). (Author)

  17. An ecophysiological study of plants growing on the fly ash deposits from the "Nikola Tesla-A" thermal power station in Serbia.

    Science.gov (United States)

    Pavlović, Pavle; Mitrović, Miroslava; Djurdjević, Lola

    2004-05-01

    This ecophysiological research on the ash deposits from the "Nikola Tesla-A" thermal power station in Serbia covered 10 plant species (Tamarix gallica, Populus alba, Spiraea van-hauttei, Ambrosia artemisifolia, Amorpha fruticosa, Eupatorium cannabinum, Crepis setosa, Epilobium collinum, Verbascum phlomoides, and Cirsium arvense). This paper presents the results of a water regime analysis, photosynthetic efficiency and trace elements (B, Cu, Mn, Zn, Pb, and Cd) content in vegetative plant parts. Water regime parameters indicate an overall stability in plant-water relations. During the period of summer drought, photosynthetic efficiency (Fv/Fm) was low, ranging from 0.429 to 0.620 for all the species that were analyzed. An analysis of the tissue trace elements content showed a lower trace metal concentration in the plants than in the ash, indicating that heavy metals undergo major concentration during the combustion process and some are not readily taken up by plants. The Zn and Pb concentrations in all of the examined species were normal whereas Cu and Mn concentrations were in the deficiency range. Boron concentrations in plant tissues were high, with some species even showing levels of more than 100 microg/g (Populus sp., Ambrosia sp., Amorpha sp., and Cirsium sp.). The presence of Cd was not detected. In general, it can be concluded from the results of this research that biological recultivation should take into account the existing ecological, vegetation, and floristic potential of an immediate environment that is abundant in life forms and ecological types of plant species that can overgrow the ash deposit relatively quickly. Selected species should be adapted to toxic B concentrations with moderate demands in terms of mineral elements (Cu and Mn).

  18. pH-dependent leaching of dump coal ash - retrospective environmental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, A.; Djordjevic, D. [University of Belgrade, Belgrade (Serbia). Dept. of Chemistry

    2009-07-01

    Trace and major elements in coal ash particles from dump of 'Nikola Tesla A' power plant in Obrenovac near Belgrade (Serbia) can cause pollution, due to leaching by atmospheric and surface waters. In order to assess this leaching potential, dump ash samples were subjected to extraction with solutions of decreasing pH values (8.50, 7.00, 5.50, and 4.00), imitating the reactions of the alkaline ash particles with the possible alkaline, neutral, and acidic (e.g., acid rain) waters. The most recently deposited ash represents the greatest environmental threat, while 'aged' ash, because of permanent leaching on the dump, was shown to have already lost this pollution potential. On the basis of the determined leachability, it was possible to perform an estimation of the acidity of the regional rainfalls in the last decades.

  19. Effect of electron degeneracy on fast-particles energy deposition in dense plasma systems

    International Nuclear Information System (INIS)

    Johzaki, T.; Nakao, Y.; Nakashima, H.; Kudo, K.

    1997-01-01

    The effects of electron degeneracy on fast-particles energy deposition in dense plasmas are investigated by making transport calculations for the fast particles. It is found that the degeneracy substantially affects the profiles of energy deposition of 3.52-MeV α-particles. On the other hand, the effect on the energy deposition of 14.1-MeV neutrons is negligibly small because the recoil ions, which transfer the neutron energy to the plasma constituents, are produced in a whole plasma volume due to the long mean-free-path of neutrons. The coupled transport-hydrodynamic calculations show that these effects of degeneracy are negligible in the ignition and burn characteristics of central ignition D-T targets. (author)

  20. Deposition characteristics of copper particles on roughened substrates through kinetic spraying

    International Nuclear Information System (INIS)

    Kumar, S.; Bae, Gyuyeol; Lee, Changhee

    2009-01-01

    In this paper, a systematic study of copper particle deposition behavior on polished and roughened surfaces (aluminum and copper) in kinetic spray process has been performed. The particle deformation behavior was simulated through finite element analysis (FEA) software ABAQUS explicit 6.7-2. The particle-substrate contact time, contact temperature and contact area upon impact have been estimated for smooth and three different roughened substrate cases. Copper powders were deposited on smooth and grit-blasted copper and aluminium substrates and characterized through scanning electron microscopy and Romulus bond strength analyzer. The results indicate that the deformation and the resultant bonding were higher for the roughened substrates than that of smooth. The characteristic factors for bonding are reported and discussed. Thus the substrate roughness appears to be beneficial for the initial deposition efficiency of the kinetic spray process.

  1. Deposition of Fungal Particles in the Lung of Workers in a Spin Factory (Minia City/ Egypt)

    International Nuclear Information System (INIS)

    Moustafa, M.; Moustafa, M.; Hofmann, W.; Winkler-Heil, R.

    2010-01-01

    Elevated levels of particle air pollution have been associated with decreased lung function, increased respiratory symptoms such as cough, shortness of breath, wheezing and asthma attacks, as well as chronic obstructive pulmonary disease (COPD), cardiovascular diseases and lung cancer (World Health Organisation, 2002). Recently, characterization of biological particles has become an important issue because of the related health effects of exposure to bio aerosols in the indoor environment influencing the intensity of sick building syndrome symptoms, such as nasal and pharyngeal mucous membrane irritations, skin dryness, itchy eyes, breathlessness, wheezing, headache, concentration problems or fatigue. Dust particles often act as a carrier for biological particles either naturally occurring or artificially generated. In cotton-spinning mills cotton dust is the major carrier for biological particles that contribute to such respiratory problems and its effect on pulmonary function among workers employed in the factory. Therefore, the aim of our study was to determine the deposition of bio aerosol particles in the human respiratory tract applying a stochastic lung model using the standard breathing parameters (ICRP, 1994) for light exercise activity. We use the size distribution parameters of bio aerosols from our previous experimental study in a cotton spin factory in Minya city (Egypt). It was found that the number of deposited particles in the lung is higher in the carding and blowing department (high cotton dust exposure) than the predicted value for the spinning department (low cotton dust exposure). The results also reveal significant dependence of fungal deposition in the lung on their composition (genera and species), concentration and size where the number of deposited Aspergillus niger particles is higher than that of the Penicillium particles in both departments

  2. Protonation of the polyethyleneimine and titanium particles and their effect on the electrophoretic mobility and deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Kok-Tee, E-mail: ktlau@utem.edu.my [Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100, Durian Tunggal, Melaka (Malaysia); Anand, T. Joseph Sahaya [Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100, Durian Tunggal, Melaka (Malaysia); Sorrell, Charles C. [School of Materials Science and Engineering, UNSW Australia, Sydney, NSW 2052 (Australia)

    2016-10-01

    Proton activities of suspensions of Ti particles with added cationic polyelectrolyte as a function of acid additions have been investigated and compared in terms of the electrophoretic mobility and deposition yield. The proton activity in ethanol medium decreased with the addition of PEI polyelectrolyte and reduced further in the presence of Ti particles. The decrease in proton activity in the suspension indicates that protonation occurred on both the PEI molecules and Ti particles. It is proposed that the protonation of the amine groups of PEI and hydroxyl sites of Ti particle led to the formation of hydrogen bonding between the Ti particle and PEI molecules. Increase in the PEI and Ti with increasing acid addition translated to higher electrophoretic mobilities and deposition yield at low ranges of acetic acid addition (<0.75 vol%). - Highlights: • Protonation characteristics of polyelectrolytes and suspension particles are reported. • The protonation characteristics explained the electrophoretic mobility and yield results. • Adsorption mechanisms of protonated polyelectrolytes on the titanium particle is proposed. • Hydroxyl sites on the particles link the oxide particle and the polyelectrolyte molecules.

  3. Protonation of the polyethyleneimine and titanium particles and their effect on the electrophoretic mobility and deposition

    International Nuclear Information System (INIS)

    Lau, Kok-Tee; Anand, T. Joseph Sahaya; Sorrell, Charles C.

    2016-01-01

    Proton activities of suspensions of Ti particles with added cationic polyelectrolyte as a function of acid additions have been investigated and compared in terms of the electrophoretic mobility and deposition yield. The proton activity in ethanol medium decreased with the addition of PEI polyelectrolyte and reduced further in the presence of Ti particles. The decrease in proton activity in the suspension indicates that protonation occurred on both the PEI molecules and Ti particles. It is proposed that the protonation of the amine groups of PEI and hydroxyl sites of Ti particle led to the formation of hydrogen bonding between the Ti particle and PEI molecules. Increase in the PEI and Ti with increasing acid addition translated to higher electrophoretic mobilities and deposition yield at low ranges of acetic acid addition (<0.75 vol%). - Highlights: • Protonation characteristics of polyelectrolytes and suspension particles are reported. • The protonation characteristics explained the electrophoretic mobility and yield results. • Adsorption mechanisms of protonated polyelectrolytes on the titanium particle is proposed. • Hydroxyl sites on the particles link the oxide particle and the polyelectrolyte molecules.

  4. Experimental investigations on the deposition and remobilization of aerosol particles in turbulent flows

    International Nuclear Information System (INIS)

    Barth, Thomas

    2014-01-01

    Aerosol particle deposition and resuspension experiments in turbulent flows were performed to investigate the complex particle transport phenomena and to provide a database for the development and validation of computational fluid dynamics (CFD) codes. The background motivation is related to the source term analysis of an accidental depressurization scenario of a High Temperature Reactor (HTR). During the operation of former HTR pilot plants, larger amounts of radio-contaminated graphite dust were found in the primary circuit. This dust most likely arose due to abrasion between the graphitic core components and was deposited on the inner wall surfaces of the primary circuit. In case of an accident scenario, such as a depressurization of the primary circuit, the dust may be remobilized and may escape the system boundaries. The estimation of the source term being discharged during such a scenario requires fundamental knowledge of the particle deposition, the amount of contaminants per unit mass as well as the resuspension phenomena. Nowadays, the graphite dust distribution in the primary circuit of an HTR can be calculated for stationary conditions using one-dimensional reactor system codes. However, it is rather unknown which fraction of the graphite dust inventory may be remobilized during a depressurization of the HTR primary circuit. Two small-scale experimental facilities were designed and a set of experiments was performed to investigate particle transport, deposition and resuspension in turbulent flows. The facility design concept is based on the fluid dynamic downscaling of the helium pressure boundary in the HTR primary circuit to an airflow at ambient conditions in the laboratory. The turbulent flow and the particles were recorded by high-resolution, non-invasive imaging techniques to provide a spatio-temporal insight into the particle transport processes. The different investigations of this thesis can be grouped into three categories. Firstly, the

  5. Stratigraphy, sedimentology and inferred flow dynamics from the July 2015 block-and-ash flow deposits at Volcán de Colima, Mexico

    Science.gov (United States)

    Macorps, Elodie; Charbonnier, Sylvain J.; Varley, Nick R.; Capra, Lucia; Atlas, Zachary; Cabré, Josep

    2018-01-01

    The July 2015 block-and-ash flow (BAF) events represent the first documented series of large-volume and long-runout BAFs generated from sustained dome collapses at Volcán de Colima. This eruption is particularly exceptional at this volcano due to (1) the large volume of BAF material emplaced (0.0077 ± 0.001 km3), (2) the long runout reached by the associated BAFs (max. 10 km), and (3) the short period ( 18 h) over which two main long-sustained dome collapse events occurred (on 10 and 11 July, respectively). Stratigraphy and sedimentology of the 2015 BAF deposits exposed in the southern flank of the volcano based on lithofacies description, grain size measurements and clast componentry allowed the recognition of three main deposit facies (i.e., valley-confined, overbank and ash-cloud surge deposits). Correlations and lithofacies variations inside three main flow units from both the valley-confined and overbank deposits left from the emplacement of the second series of BAFs on 11 July provide detailed information about: (1) the distribution, volumes and sedimentological characteristics of the different units; (2) flow parameters (i.e., velocity and dynamic pressure) and mobility metrics as inferred from associated deposits; and (3) changes in the dynamics of the different flows and their material during emplacement. These data were coupled with geomorphic analyses to assess the role of the topography in controlling the behaviour and impacts of the successive BAF pulses on the volcano flanks. Finally, these findings are used to propose a conceptual model for transport and deposition mechanisms of the July 2015 BAFs at Volcán de Colima. In this model, deposition occurs by rapid stepwise aggradation of successive BAF pulses. Flow confinement in a narrow and sinuous channel enhance the mobility and runout of individual channelized BAF pulses. When these conditions occur, the progressive valley infilling from successive sustained dome-collapse events promote the

  6. Formation of obsidian pyroclasts by sintering of ash particles in the volcanic conduit

    Science.gov (United States)

    Gardner, James E.; Llewellin, Edward W.; Watkins, James M.; Befus, Kenneth S.

    2017-02-01

    mechanism. Similar textures, and the occurrence of xenolithic material, in obsidian pyroclasts in other eruptions suggest that sintering may be generally responsible for the origin of obsidian pyroclasts. Our conceptual model indicates that volatile contents in obsidian pyroclasts reflect both degassing of bubbly magma and the composition of gas trapped between sintering particles.

  7. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China

    International Nuclear Information System (INIS)

    Cao Zongze; Yang Yuhua; Lu, Julia; Zhang Chengxiao

    2011-01-01

    Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m -2 yr -1 . The average deposition rate (76.7 g m -2 yr -1 ) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), ∼10% of the settled dusts having size 70% having size <30 μm; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: → High atmospheric dust deposition rate in Xi'an, Shaanxi, China. → Coal-burning power plan being a major source of particulate matter in Xi'an area. → High levels of toxic elements in the settled dusts. → Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China.

  8. Effect of exercise on deposition and subsequent retention of inhaled particles

    International Nuclear Information System (INIS)

    Bennett, W.D.; Messina, M.S.; Smaldone, G.C.

    1985-01-01

    To investigate the effect of exercise and its associated increase in ventilation on the deposition and subsequent retention of inhaled particles, we measured the fractional and regional lung deposition of a radioactively tagged (/sup 99m/Tc) monodisperse aerosol (2.6 microns mass median aerodynamic diam) in normal human subjects at rest and while exercising on a bicycle ergometer. Breath-by-breath deposition fraction (DF) was measured throughout the aerosol exposures by Tyndallometry. Following each exposure gamma camera analysis was used to 1) determine the regional distribution of deposited particles and 2) monitor lung retention for 2.5 h and again at 24 h. We found that DF was unchanged between ventilation at rest (6-10 l/min) and exercise (32-46 l/min). Even though mouth deposition was enhanced with exercise, it was not large enough to produce a significant difference in the deposition fraction of the lung (DFL) between resting and exercise exposures. The central-to-peripheral distribution of deposited aerosol was larger for the exercise vs. resting exposure, reflecting a shift of particle deposition to more central bronchial airways. Apical-to-basal distribution was not different for the two exposures. Retention at 2.5 h and 24 h (R24) was reduced following the exercise vs. the resting exposure, consistent with greater bronchial deposition during exercise. The product of DFL and R24 gave a measure of fractional burden at 24 h (B24), i.e., the fraction of inhaled aerosol residing in the lungs 24 h after exposure. B24 was not significantly different between rest and exercise exposures

  9. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Wallenhorst, L.M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-01-01

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  10. Dynamics of particle loading in deep-bed filter. Transport, deposition and reentrainment

    Directory of Open Access Journals (Sweden)

    Przekop Rafał

    2016-09-01

    Full Text Available Deep bed filtration is an effective method of submicron and micron particle removal from the fluid stream. There is an extensive body of literature regarding particle deposition in filters, often using the classical continuum approach. However, the approach is not convenient for studying the influence of particle deposition on filter performance (filtration efficiency, pressure drop when non-steady state boundary conditions have to be introduced. For the purposes of this work the lattice-Boltzmann model describes fluid dynamics, while the solid particle motion is modeled by the Brownian dynamics. For aggregates the effect of their structure on displacement is taken into account. The possibility of particles rebound from the surface of collector or reentrainment of deposits to fluid stream is calculated by energy balanced oscillatory model derived from adhesion theory. The results show the evolution of filtration efficiency and pressure drop of filters with different internal structure described by the size of pores. The size of resuspended aggregates and volume distribution of deposits in filter were also analyzed. The model enables prediction of dynamic filter behavior. It can be a very useful tool for designing filter structures which optimize maximum lifetime with the acceptable values of filtration efficiency and pressure drop.

  11. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wallenhorst, L.M., E-mail: lena.wallenhorst@hawk-hhg.de [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Loewenthal, L.; Avramidis, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Gerhard, C. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany); Militz, H. [Wood Biology and Wood Products, Burckhardt Institute, Georg-August-University Göttingen, Büsgenweg 4, 37077 Göttingen (Germany); Ohms, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Viöl, W. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany)

    2017-07-15

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  12. Characterization of flue gas, fly ash, aerosol and deposit compositions as a function of waste composition and grate operation

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Zeuthen, Frederik Jacob; Frandsen, Flemming

    2007-01-01

    The Danish strategy for waste management is still to increase recycling and on the same time to reduce the volume of land-filled waste, in order to avoid loss of resources, and waste incineration is an important part of this strategy. In 2004, 26 % of the total reported Danish waste production...... metals, was then mixed with the reference fuel in the individual test runs. The dedicated waste fractions comprised NaCl (road salt), batteries, automotive shredder waste, CCA (Copper-Chromate-Arsenate)-impregnated wood, PVC plastics, and (leather) shoes. Test runs with varying operational parameters, e...... times increase in concentration in fly ash compared to the reference experiments), and for Hg when firing batteries (10 times increase in concentration in fly ash). These observations were in consistence with an increased concentration of the respective elements in the specific waste fractions...

  13. Deposition of particle/bound substances during radiation fog events; Deposition von partikelgebundenen Substanzen waehrend Strahlungsnebelereignissen

    Energy Technology Data Exchange (ETDEWEB)

    Trautner, F. [Inst. fuer Strahlenschutz, GSF-Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany); Tschiersch, J. [Inst. fuer Strahlenschutz, GSF-Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany)

    1993-11-01

    During autumnal and winterly radiation fog events size fractioned sampling of aerosol rime and fogwater was carried out. Samples were collected on polyethylene plates with a surface of 0.25 m{sup 2}. The deposited fog water quantity was as high as 15g/h.m{sup 2}. Deposition rate values were between 10{sup -4} and 10{sup -2} m/s. (orig./EW) [Deutsch] Waehrend herbstlichen und winterlichen Strahlungsnebelereignissen wurde direkt nach der groessenfraktionierenden Probennahme von Aerosol Reif und Nebelwasser auf Polyethylenplatten von 0,25 m{sup 2} Oberflaeche gesammelt. Die deponierte Nebelwassermasse betrug dabei bis zu 15 g/h . m{sup 2}. Fuer Elemente, die sowohl im Wasser als auch im Aerosol analysiert wurden erreichten die Depositionsgeschwindigkeiten Werte zwischen 10{sup -4} und 10{sup -2} m/s. (orig.)

  14. Particles in wall-bounded turbulent flows deposition, re-suspension and agglomeration

    CERN Document Server

    Pozorski, Jacek

    2017-01-01

    The book presents an up-to-date review of turbulent two-phase flows with the dispersed phase, with an emphasis on the dynamics in the near-wall region. New insights to the flow physics are provided by direct numerical simuation and by fine experimental techniques. Also included are models of particle dynamics in wall-bounded turbulent flows, and a description of particle surface interactions including muti-layer deposition and re-suspension.

  15. Predicting the Effects of Powder Feeding Rates on Particle Impact Conditions and Cold Spray Deposited Coatings

    Science.gov (United States)

    Ozdemir, Ozan C.; Widener, Christian A.; Carter, Michael J.; Johnson, Kyle W.

    2017-10-01

    As the industrial application of the cold spray technology grows, the need to optimize both the cost and the quality of the process grows with it. Parameter selection techniques available today require the use of a coupled system of equations to be solved to involve the losses due to particle loading in the gas stream. Such analyses cause a significant increase in the computational time in comparison with calculations with isentropic flow assumptions. In cold spray operations, engineers and operators may, therefore, neglect the effects of particle loading to simplify the multiparameter optimization process. In this study, two-way coupled (particle-fluid) quasi-one-dimensional fluid dynamics simulations are used to test the particle loading effects under many potential cold spray scenarios. Output of the simulations is statistically analyzed to build regression models that estimate the changes in particle impact velocity and temperature due to particle loading. This approach eases particle loading optimization for more complete analysis on deposition cost and time. The model was validated both numerically and experimentally. Further numerical analyses were completed to test the particle loading capacity and limitations of a nozzle with a commonly used throat size. Additional experimentation helped document the physical limitations to high-rate deposition.

  16. Fly ash quality and utilization

    Energy Technology Data Exchange (ETDEWEB)

    Barta, L.E.; Lachner, L.; Wenzel, G.B. [Inst. for Energy, Budapest (Hungary); Beer, M.J. [Massachusetts Inst. of Technology, Cambridge, MA (United States)

    1995-12-01

    The quality of fly ash is of considerable importance to fly ash utilizers. The fly ash puzzolanic activity is one of the most important properties that determines the role of fly ash as a binding agent in the cementing process. The puzzolanic activity, however is a function of fly ash particle size and chemical composition. These parameters are closely related to the process of fly ash formation in pulverized coal fired furnaces. In turn, it is essential to understand the transformation of mineral matter during coal combustion. Due to the particle-to-particle variation of coal properties and the random coalescence of mineral particles, the properties of fly ash particles e.g. size, SiO{sub 2} content, viscosity can change considerably from particle to particle. These variations can be described by the use of the probability theory. Since the mean values of these randomly changing parameters are not sufficient to describe the behavior of individual fly ash particles during the formation of concrete, therefore it is necessary to investigate the distribution of these variables. Examples of these variations were examined by the Computer Controlled Scanning Electron Microscopy (CCSEM) for particle size and chemical composition for Texas lignite and Eagel Butte mineral matter and fly ash. The effect of combustion on the variations of these properties for both the fly ash and mineral matter were studied by using a laminar flow reactor. It is shown in our paper, that there are significant variations (about 40-50% around the mean values) of the above-listed properties for both coal samples. By comparing the particle size and chemical composition distributions of the mineral matter and fly ash, it was possible to conclude that for the Texas lignite mineral matter, the combustion did not effect significantly the distribution of these properties, however, for the Eagel Butte coal the combustion had a major impact on these mineral matter parameters.

  17. Efficiency of the deposition mode ice nucleation on mineral dust particles

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2006-01-01

    Full Text Available The deposition mode ice nucleation efficiency of various dust aerosols was investigated at cirrus cloud temperatures between 196 and 223 K using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and Dynamics in the Atmosphere. Arizona test dust (ATD as a reference material and two dust samples from the Takla Makan desert in Asia (AD1 and the Sahara (SD2 were used for the experiments at simulated cloud conditions. The dust particle sizes were almost lognormally distributed with mode diameters between 0.3 and 0.5 μm and geometric standard deviations between 1.6 and 1.9. Deposition ice nucleation was most efficient on ATD particles with ice-active particle fractions of about 0.6 and 0.8 at an ice saturation ratio SiSiSi. This indicates that deposition ice nucleation on mineral particles may not be treated in the same stochastic sense as homogeneous freezing. The suggested formulation of ice activation spectra may be used to calculate the formation rate of ice crystals in models, if the number concentration of dust particles is known. More experimental work is needed to quantify the variability of the ice activation spectra as function of the temperature and dust particle properties.

  18. Indoor particle dynamics in a school office: determination of particle concentrations, deposition rates and penetration factors under naturally ventilated conditions.

    Science.gov (United States)

    Cong, X C; Zhao, J J; Jing, Z; Wang, Q G; Ni, P F

    2018-05-09

    Recently, the problem of indoor particulate matter pollution has received much attention. An increasing number of epidemiological studies show that the concentration of atmospheric particulate matter has a significant effect on human health, even at very low concentrations. Most of these investigations have relied upon outdoor particle concentrations as surrogates of human exposures. However, considering that the concentration distribution of the indoor particulate matter is largely dependent on the extent to which these particles penetrate the building and on the degree of suspension in the indoor air, human exposures to particles of outdoor origin may not be equal to outdoor particle concentration levels. Therefore, it is critical to understand the relationship between the particle concentrations found outdoors and those found in indoor micro-environments. In this study, experiments were conducted using a naturally ventilated office located in Qingdao, China. The indoor and outdoor particle concentrations were measured at the same time using an optical counter with four size ranges. The particle size distribution ranged from 0.3 to 2.5 μm, and the experimental period was from April to September, 2016. Based on the experimental data, the dynamic and mass balance model based on time was used to estimate the penetration rate and deposition rate at air exchange rates of 0.03-0.25 h -1 . The values of the penetration rate and deposition velocity of indoor particles were determined to range from 0.45 to 0.82 h -1 and 1.71 to 2.82 m/h, respectively. In addition, the particulate pollution exposure in the indoor environment was analyzed to estimate the exposure hazard from indoor particulate matter pollution, which is important for human exposure to particles and associated health effects. The conclusions from this study can serve to provide a better understanding the dynamics and behaviors of airborne particle entering into buildings. And they will also highlight

  19. Development of estimation method for tephra transport and dispersal characteristics with numerical simulation technique. Part 2. A method of selecting meteorological conditions and the effects on ash deposition and concentration in air for Kanto-area

    International Nuclear Information System (INIS)

    Hattori, Yasuo; Suto, Hitoshi; Toshida, Kiyoshi; Hirakuchi, Hiromaru

    2016-01-01

    In the present study, we examine the estimation of ground deposition for a real test case, a volcanic ash hazard in Kanto-area with various meteorological conditions by using an ash transport- and deposition-model, fall3d; we consider three eruptions, which correspond to the stage 1 and 3 of Hoei eruption at Mt. Fuji and Tenmei Eruption at Mt. Asama. The meteorological conditions are generated with the 53 years reanalysis meteorological dataset, CRIEPI-RCM-Era2, which has a temporal- and spatial-resolutions of 1 hr and 5 km. The typical and extreme conditions were sampled by using Gumbel plot and an artificial neural network technique. The ash deposition is invariably limited to the west area of the vent, even with the typical wind conditions on summer, while the isopach of ground deposition depicted various distributions, which strongly depends on meteorological conditions. This implies that the concentric circular distribution must not be realistic. Also, a long-term eruption, such as the Hoei eruption during stage 3, yields large deposition area due to the daily variations of wind direction, suggesting that the attention to the differences between daily variation and fluctuations of wind direction on evaluating of volcanic ash risk is vital. (author)

  20. A modeling study of the effect of gravity on airflow distribution and particle deposition in the lung.

    Science.gov (United States)

    Asgharian, Bahman; Price, Owen; Oberdörster, Gunter

    2006-06-01

    Inhalation of particles generated as a result of thermal degradation from fire or smoke, as may occur on spacecraft, is of major health concern to space-faring countries. Knowledge of lung airflow and particle transport under different gravity environments is required to addresses this concern by providing information on particle deposition. Gravity affects deposition of particles in the lung in two ways. First, the airflow distribution among airways is changed in different gravity environments. Second, particle losses by sedimentation are enhanced with increasing gravity. In this study, a model of airflow distribution in the lung that accounts for the influence of gravity was used for a mathematical description of particle deposition in the human lung to calculate lobar, regional, and local deposition of particles in different gravity environments. The lung geometry used in the mathematical model contained five lobes that allowed the assessment of lobar ventilation distribution and variation of particle deposition. At zero gravity, it was predicted that all lobes of the lung expanded and contracted uniformly, independent of body position. Increased gravity in the upright position increased the expansion of the upper lobes and decreased expansion of the lower lobes. Despite a slight increase in predicted deposition of ultrafine particles in the upper lobes with decreasing gravity, deposition of ultrafine particles was generally predicted to be unaffected by gravity. Increased gravity increased predicted deposition of fine and coarse particles in the tracheobronchial region, but that led to a reduction or even elimination of deposition in the alveolar region for coarse particles. The results from this study show that existing mathematical models of particle deposition at 1 G can be extended to different gravity environments by simply correcting for a gravity constant. Controlled studies in astronauts on future space missions are needed to validate these predictions.

  1. High ash fuels for diesel engines II; Korkean tuhkapitoisuuden omaavan polttoaineen kaeyttoe dieselvoimaloissa II

    Energy Technology Data Exchange (ETDEWEB)

    Norrmen, E.; Vestergren, R.; Svahn, P. [Wartsila Diesel International Ltd, Vaasa (Finland)

    1996-12-01

    Heavy fuel oils containing a large amount of ash, that is used in some geographically restricted areas, can cause problems with deposit formation and hot corrosion, leading to burned exhaust gas valves in some diesel engines. The Liekki 2 programs Use of high ash fuel in diesel power plants I and II have been initiated to clarify the mechanisms of deposit formation, and start and propagation of hot corrosion. The aim is to get enough knowledge to enable the development of the Waertsilae diesel engines to be able to handle heavy fuel with a very high ash content. The chemistry, sintering, melting, and corrosiveness of deposits from different part of the diesel engine and on different exhaust valve materials, as well as the chemistry in different depths of the deposit have been investigated. Theories for the mechanisms mentioned above have been developed. Additives changing the sintering/melting point and physical properties of the formed deposits have been screened. Exhaust gas particle measurements have been performed when running on high ash fuel, both without deposit modifying fuel additive and with. The results have been used to verify the ABC (Aerosol Behaviour in Combustion) model, and the particle chemistry and morphology has been examined. Several tests, also high load endurance tests have been run in diesel engines with high ash fuels. (author)

  2. Deposition and retention of 67Ga-labelled diesel particles in Fischer-344 rats

    International Nuclear Information System (INIS)

    Wolff, R.K.; Sun, J.D.; Lopez, J.A.; Wolf, I.; Cheng, Y.S.; McClellan, R.O.

    1981-01-01

    Fischer-344 rats were exposed nose-only to 67 Ga radiolabeled diesel exhaust particles produced from a 1 cylinder engine and diluted 10:1 with filtered air. Volume median diameters of the particles were 0.14 to 0.16 μm measured using an electrical aerosol analyzer, a diffusion battery and a cascade impactor. Initial lung deposition was 7 +- 2% and 12 +- 2% in two separate experiments. Gallium-67 left the lung rapidly with a clearance half-time of about 10 days, indicating that the 67 Ga label dissociated from diesel particles

  3. Lung Deposition Calculations for Radioactive Aerosol Particles Originating from Caves and Uranium Mines

    International Nuclear Information System (INIS)

    Alfoldy, B.; Torok, Sz.; Winkler, R.

    2001-01-01

    Full text: The present study simulates lung deposition of radioactive aerosol particles originating from the atmosphere of a therapeutic cave (Szemlohegyi cave, Budapest) and several uranium mines. Particle deposition patterns and surface densities have been calculated by the stochastic lung model of Koblinger and Hofmann. In the model, deposition can be caused by the simultaneous effects of Brownian motion, inertial impaction and gravitational settling. The calculations were carried out by considering the aerosol particle size distribution and radon concentration of the atmosphere of the cave and mines. The deposition was computed in the whole lung, in characteristic parts of the respiratory system such as extrathoracic, tracheobronchial, acinar and alveolar regions and in the singe airway generations at different flow rates for adults. The adverse health effects of inhaled radionuclides strongly depend from the local deposition density values in cellular dimensions. Thus we will built in the results to a cellular effects model of Balashazy and Hofmann for the simulation of the pathological effects of inhaled radionuclides for risk assessment. (author)

  4. Modelling Measured Deposition and Resuspension Rates of Particles in Animal Buildings

    DEFF Research Database (Denmark)

    Lengweiler, P.; Moser, A.; Nielsen, Peter V.

    on the surfaces is shown as a function of time. High contents of organic dust in animal buildings can affect the health of both people and animals. Deposition on indoor surfaces is an important removal mechanism to reduce the airborne particle concentration. As a basis to develop methods to eliminate dust related...

  5. Speciated particle dry deposition to the sea surface: Results from ASEPS '97

    DEFF Research Database (Denmark)

    Pryor, S.C.; Barthelmie, R.J.; Geernaert, L.L.S.

    1999-01-01

    on Precipitation Scavenging and Atmosphere-Surface Exchange Processes. AMS, Richland, Washington, USA, 12pp.) model to calculate size-segregated dry deposition of particle inorganic nitrogen compounds to the western Baltic during the late Spring of 1997 based on data collected as part of the Air-Sea Exchange...

  6. TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS

    Science.gov (United States)

    TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS. Zhe Zhang*, Huawei Shi, Clement Kleinstreuer, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910; Chong S. Kim, National Health and En...

  7. Electrostatic deposition of a micro solder particle using a single probe by applying a single rectangular pulse

    International Nuclear Information System (INIS)

    Nakabayashi, Daizo; Sawai, Kenji; Saito, Shigeki; Takahashi, Kunio

    2012-01-01

    Recently, micromanipulation techniques have been in high demand. A technique to deposit a metal microparticle onto a metal substrate by using a single metal probe has been proposed as one of the techniques. A solder particle with a diameter of 20–30 µm, initially adhering to the probe tip, is detached and deposited onto a substrate. The success rate of the particle deposition was 44% in the previous research, and is insufficient for industrial applications. In this paper, a technique of particle deposition by applying a single rectangular pulse is proposed, and the mechanism of the deposition is described. In the mechanism, an electric discharge between the probe and the particle when the particle reaches the substrate plays an important role in the particle deposition. Moreover, the mechanism of the proposed technique is verified by experiments of particle deposition, which are observed using a high-speed camera, a scanning electron microscope (SEM) and an oscilloscope. The success rate of the particle deposition has increased to 93% by the proposed technique. Furthermore, the damage to the particle by the electric discharge is evaluated using an RC circuit model, and the applicability of the proposed technique is discussed. (paper)

  8. Theoretical modeling of fine-particle deposition in 3-dimensional bronchial bifurcations

    International Nuclear Information System (INIS)

    Shaw, D.T.; Rajendran, N.; Liao, N.S.

    1978-01-01

    A theoretical model is developed for the prediction of the peak to average particle deposition flux in the human bronchial airways. The model involves the determination of the peak flux by a round-nose 2-dimensional bifurcation channel and the average deposition flux by a curved-tube model. The ''hot-spot'' effect for all generations in the human respiratory system is estimated. Hot spots are usually associated with the sites of bronchoconstriction or even chronic bronchitis and lung cancer. Recent studies indicate that lung cancer in smokers may be caused by the deposition of radioactive particles produced by the burning of tobacco leaves. High local concentrations of Po-210 have been measured in epithelium from bronchial bifurcations of smokes. This Po-210 is the radioactive daughter of Pb-210 which is produced from a long chain of radioactive decay starting from uranium in the fertilizer-enriched soil. It is found that the peak deposition flux is higher than the average deposition flux by a factor ranging between 5 and 30, depending on the generation number. The importance of this peak to average deposition flux ratio on consideration of environmental safety studies is discussed

  9. Researches Regarding the Adaptation Process of the Species Miscanthus Giganteus under the Conditions of Fly Ash Deposit from Utvin, Timis County

    Directory of Open Access Journals (Sweden)

    Benoni Lixandru

    2013-05-01

    Full Text Available Miscanthus giganteus is a large, perennial (up to 20 years grass hybrid of M. sinensis and M. sacchariflorus native to Japan. Is a C4 carbon fixation plant, and thus exhibits greater photosynthetic efficiency and lower water use requirements than other kinds of plants. It has very low nutritional requirements – it has high nitrogen use efficiency and therefore is capable of growing well on barren land without the aid of heavy fertilization. M. giganteus is a sterile hybrid, therefore propagates vegetative through its rhizomes and that it is a completely non-invasive species. In this paper are presented the results of this grass species growing on fly ash deposit Utvin after the first year from the planting. Order to stimulate the process of vegetative from the first year, have used three different fertilizing: with sewage sludge, with cattle manure and mineral supplement such as N.P.K. We have also provided an adequate irrigation during dry periods of the summer. The best germination percentage was obtained in variants fertilized with sewage sludge and manure of cattle. Further the same variations recorded a good growth rate and higher biomass production. However, good production of biomass produced in the first year of all variants show a good adaptability of the species M. giganteus to arid biotope conditions of the fly ash dump.

  10. In search for a compromise between biodiversity conservation and human health protection in restoration of fly ash deposits: effect of anti-dust treatments on five groups of arthropods.

    Science.gov (United States)

    Tropek, Robert; Cerna, Ilona; Straka, Jakub; Kocarek, Petr; Malenovsky, Igor; Tichanek, Filip; Sebek, Pavel

    2016-07-01

    Recently, fly ash deposits have been revealed as a secondary refuge of critically endangered arthropods specialised on aeolian sands in Central Europe. Simultaneously, these anthropogenic habitats are well known for their negative impact on human health and the surrounding environment. The overwhelming majority of these risks are caused by wind erosion, the substantial decreasing of which is thus necessary. But, any effects of anti-dust treatments on endangered arthropods have never been studied. We surveyed communities of five arthropod groups (wild bees and wasps, leafhoppers, spiders, hoverflies and orthopteroid insects) colonising three fly ash deposits in the western Czech Republic. We focused on two different anti-dust treatments (~70 and 100 % cover of fly ash by barren soil) and their comparison with a control of bare fly ash. Altogether, we recorded 495 species, including 132 nationally threatened species (eight of them were considered to be extinct in the country) and/or 30 species strictly specialised to drift sands. Bees and wasps and leafhoppers contained the overwhelming majority of species of the highest conservation interest; a few other important records were also in spiders and orthopteroids. Total soil cover depleted the unique environment of fly ash and thus destroyed the high conservation potential of the deposits. On the other hand, partial coverage (with ~30 % of bare fly ash) still offered habitats for many of the most threatened species, as we showed by both regression and multivariate analyses, with a decrease of wind erosion. This topic still needs much more research interest, but we consider mosaic-like preservation of smaller spots of fly ash as one of the possible compromises between biodiversity and human health.

  11. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Science.gov (United States)

    Wallenhorst, L. M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-07-01

    In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  12. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    International Nuclear Information System (INIS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm 2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  13. Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia

    Energy Technology Data Exchange (ETDEWEB)

    Gunawardena, Janaka, E-mail: j.gunawardena@qut.edu.au; Ziyath, Abdul M., E-mail: mohamed.ziyath@qut.edu.au; Bostrom, Thor E., E-mail: t.bostrom@qut.edu.au; Bekessy, Lambert K., E-mail: l.bekessy@qut.edu.au; Ayoko, Godwin A., E-mail: g.ayoko@qut.edu.au; Egodawatta, Prasanna, E-mail: p.egodawatta@qut.edu.au; Goonetilleke, Ashantha, E-mail: a.goonetilleke@qut.edu.au

    2013-09-01

    The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. - Highlights: • The dust storm contributed a large fraction of fine particles to pollutant build-up. • The dust storm increased TSS, Al, Fe and Mn loads in build-up on ground surfaces. • Dust storm did not significantly increase TOC, Ni, Cu, Pb and Cd loads in build-up. • Cr and Zn in dust storm deposition were contributed by local anthropogenic sources.

  14. Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia

    International Nuclear Information System (INIS)

    Gunawardena, Janaka; Ziyath, Abdul M.; Bostrom, Thor E.; Bekessy, Lambert K.; Ayoko, Godwin A.; Egodawatta, Prasanna; Goonetilleke, Ashantha

    2013-01-01

    The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. - Highlights: • The dust storm contributed a large fraction of fine particles to pollutant build-up. • The dust storm increased TSS, Al, Fe and Mn loads in build-up on ground surfaces. • Dust storm did not significantly increase TOC, Ni, Cu, Pb and Cd loads in build-up. • Cr and Zn in dust storm deposition were contributed by local anthropogenic sources

  15. Physical, chemical, and mineralogical data from surficial deposits, groundwater levels, and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada

    Science.gov (United States)

    Goldstein, Harland L.; Breit, George N.; Yount, James C.; Reynolds, Richard L.; Reheis, Marith C.; Skipp, Gary L.; Fisher, Eric M.; Lamothe, Paul J.

    2011-01-01

    This report presents data and describes the methods used to determine the physical attributes, as well as the chemical and mineralogical composition of surficial deposits; groundwater levels; and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada. The results support studies that examine (1) the interaction between groundwater and the ground surface, and the transport of solutes through the unsaturated zone; (2) the potential for the accumulation of metals and metalloids in surface crusts; (3) emission of dust from metal-rich salt crust; and (4) the effects of metal-rich dusts on human and ecosystem health. The evaporation of shallow (travel as atmospheric dust and affect human and ecosystem health at local to regional scales.

  16. Hail formation triggers rapid ash aggregation in volcanic plumes.

    Science.gov (United States)

    Van Eaton, Alexa R; Mastin, Larry G; Herzog, Michael; Schwaiger, Hans F; Schneider, David J; Wallace, Kristi L; Clarke, Amanda B

    2015-08-03

    During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized 'wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits.

  17. Biological and chemical interactions excelerating the removal of impurities from fly ashes

    Directory of Open Access Journals (Sweden)

    Štyriaková Iveta

    2002-03-01

    Full Text Available The mesophilic bacteria were isolated from the deposit of fly ash in Chalmová (Slovakia and identified using the BBL identification system. Bacillus cereus was the dominant species in this deposit of aluminosilicate minerals. Under laboratory conditions , Bacillus cereus accelerated the extraction of major and trace impurities in fly ash during bioleaching processes. This process was dependent on bacterial adhesion and production of organic acids. The effect of organic acids produced by bacteria was detected especially in sites where impregnated metals were found in the aluminosilicate structure. Amorphous spherical aluminosilicate particles in allotriomorphic aluminosilicate grains represent a main mineral component of fly-ash in which also elements such as Fe, Ti, Mn, As are bound. The rate of mobilization of Al, Si and Ti from coal fly ash under biochemically relevant conditions in vitro was previously shown to depend on the quantity of the ash microspheres. The qualitative EDS analyse of leachates confirmed the extraction of toxic elements (As and Mn from the initial sample of fly ash.Heterotrophic bacteria of Bacillus genus are capable to remove impurities from deposited fly-ash. A long-term deposition of energy fly-ash causes chemical and mineralogical changes as a result of weathering processes. Depending on the composition of coal concentrate containing SiO2, Al2O3, Fe2O3, CaO, MgO and other oxides, fly ash can provide a useful preliminary batch for the preparation of glass-ceramics or zeolite after extracting of bacterially dissolved elements from it. The mobility of major impurities (Ca and Fe and heavy metals, caused by biochemical leaching of fly ash, suggests the possibility of the development of an alternative way of this raw material treatment. The advantage of bioleaching is relatively low cost and the subsequent low demand for energy compared with conventional technologies.

  18. Development of a dual-tracer real-time particle dry-deposition measurement technique for simple and complex terrain

    International Nuclear Information System (INIS)

    Sehmel, G.A.; Hodgson, W.H.; Campbell, J.A.

    1979-01-01

    Detectors are being developed and tested for measuring the airborne concentrations of lithium particles and SF 6 gas in real time. The airborne lithium detector will be used for real-time measurements of both particle dry-deposition velocities and resuspension rates. Both the lithium and SF 6 detectors will be used for measuring dry deposition in field experiments

  19. Particle re-entrainment from a powder deposit in an horizontal air flow

    International Nuclear Information System (INIS)

    Alloul, L.; Witschger, O.; Alloul, L.; Renoux, A.; Le Dur, D.; Monnatte, J.

    2000-01-01

    Particle re-entrainment from surfaces to turbulent air flow is an important subject in many different fields like nuclear safety, environmental air pollution, sediment transport by wind, surface contamination in semiconductor operations. Theoretical and experimental studies have been numerous and cover different aspects of the phenomena. Although a number of theoretical works have been devoted for describing the mechanisms of detachment of primary spherical particles form flat smooth surfaces in a turbulent flow, experimental data are still needed in order to comparison. Moreover, the knowledge of the effect of parameters related to the deposit (monolayer, multilayer, cone-like pile), the powder particles (particle-size distribution, adhesive properties), the surface (roughness,...),the airflow (velocity, acceleration, turbulence) or the environment (humidity,...) is still in an elementary stage. The main objective of our work is to contribute to the understanding and quantification of the parameters that govern the particle re-entrainment from a powder deposit in an turbulent horizontal airflow. Therefore, a new experimental facility called BISE (french acronym for wind tunnel for studying particle re-entrainment by airflow) has been designed and built in our laboratory. (authors)

  20. Deposition uniformity, particle nucleation and the optimum conditions for CVD in multi-wafer furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, S.K.; Nilson, R.H.

    1996-06-01

    A second-order perturbation solution describing the radial transport of a reactive species and concurrent deposition on wafer surfaces is derived for use in optimizing CVD process conditions. The result is applicable to a variety of deposition reactions and accounts for both diffusive and advective transport, as well as both ordinary and Knudsen diffusion. Based on the first-order approximation, the deposition rate is maximized subject to a constraint on the radial uniformity of the deposition rate. For a fixed reactant mole fraction, the optimum pressure and optimum temperature are obtained using the method of Lagrange multipliers. This yields a weak one-sided maximum; deposition rates fall as pressures are reduced but remain nearly constant at all pressures above the optimum value. The deposition rate is also maximized subject to dual constraints on the uniformity and particle nucleation rate. In this case, the optimum pressure, optimum temperature and optimum reactant fraction are similarly obtained, and the resulting maximum deposition rate is well defined. These results are also applicable to CVI processes used in composites manufacturing.

  1. Fusion-product ash buildup in tokamak with radial electric field

    International Nuclear Information System (INIS)

    Downum, W.B.; Choi, C.K.; Miley, G.H.

    1979-01-01

    The buildup of thermalized fusion products (ash) in a tokamak can seriously limit burn times. Prior studies have concentrated on deposition profile effects on alpha particle transport in tokamaks but have not considered the effect on ash of radial electric fields (either created internally, e.g. due to high-energy alpha leakage, or generated externally). The present study focuses on this issue since it appears that electric fields might offer one approach to control of the ash. Approximate field and source profiles are used, based on prior calculations

  2. Factors controlling alkali salt deposition in recovery boilers - particle formation and deposition; Soodakattilan likaantuminen ja siihen vaikuttavien tekijoeiden hallinta - hiukkasten muodostuminen ja depositio

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E.I.; Mikkanen, P.; Ylaetalo, S. [VTT Chemistry, Espoo (Finland); Jokiniemi, J.K.; Lyyraenen, J.; Pyykoenen, J.; Saastamoinen, J. [VTT Energy, Espoo (Finland)

    1996-12-01

    In this project, the aim was to find out those critical factors that control the deposit formation in the recovery boilers. We focus on the particle formation, growth and deposition as well as the single black liquor particle combustion behaviour. The final goal is the development of the predictive model to be used to describe deposit growth and subsequent behaviour as well as the dependence of deposition on black liquor characteristics and boiler operation conditions. During year 1995 an experimental study on the aerosol particle formation within the recovery boiler furnace and a sensitivity study with the Aerosol Behaviour in Combustion (ABC) code were carried out. The experimental study confirmed the fact that the particles are already formed in the recovery boiler furnace. The particle formation is initiated in the boundary layer of the burning droplet or smelt bed, where metals are vaporised and oxidised to form tiny seed particles. Trace amounts of metals were measured in all particle sizes and the sensitivity study with the ABC model gave further evidence of the seed formation was necessary primary step in the particle formation. At the furnace outlet the sintration ratio and the sulfation ratio of the particles were dependent on the furnace temperature and the residence time in the furnace. At ESP inlet three types of particles were observed (1) fine particles with the major mass mode at about 1-2 {mu}m, (2) large agglomerates in sizes larger than 8 {mu}m, and (3) spherical particles about 2-4 {mu}m in size. The fine particles were formed from vapours and the large agglomerates were formed from fine particles agglomerated on heat exchanger surfaces and re-entrained back to flue gas flow. The large agglomerates also contain vapours that have directly condensed to surfaces. The large spherical particles contain silicon and pass the process almost unchanged. (Abstract Truncated)

  3. Characterization of Spatial Impact of Particles Emitted from a Cement Material Production Facility on Outdoor Particle Deposition in the Surrounding Community.

    Science.gov (United States)

    Yu, Chang Ho; Fan, Zhihua Tina; McCandlish, Elizabeth; Stern, Alan H; Lioy, Paul J

    2011-10-01

    The objective of this study was to estimate the contribution of a facility that processes steel production slag into raw material for cement production to local outdoor particle deposition in Camden, NJ. A dry deposition sampler that can house four 37-mm quartz fiber filters was developed and used for the collection of atmospheric particle deposits. Two rounds of particle collection (3-4 weeks each) were conducted in 8-11 locations 200-800 m downwind of the facility. Background samples were concurrently collected in a remote area located ∼2 km upwind from the facility. In addition, duplicate surface wipe samples were collected side-by-side from each of the 13 locations within the same sampling area during the first deposition sampling period. One composite source material sample was also collected from a pile stored in the facility. Both the bulk of the source material and the particle deposition flux in the study area was higher (24-83 mg/m 2 ·day) than at the background sites (13-17 mg/m 2 ·day). The concentration of Ca, a major element in the cement source production material, was found to exponentially decrease with increasing downwind distance from the facility (P particle deposition. The contribution of the facility to outdoor deposited particle mass was further estimated by three independent models using the measurements obtained from this study. The estimated contributions to particle deposition in the study area were 1.8-7.4% from the regression analysis of the Ca concentration in particle deposition samples against the distance from the facility, 0-11% from the U.S. Environmental Protection Agency (EPA) Chemical Mass Balance (CMB) source-receptor model, and 7.6-13% from the EPA Industrial Source Complex Short Term (ISCST3) dispersion model using the particle-size-adjusted permit-based emissions estimates. [Box: see text].

  4. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China

    Energy Technology Data Exchange (ETDEWEB)

    Cao Zongze; Yang Yuhua [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Lu, Julia, E-mail: julialu@ryerson.c [Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Zhang Chengxiao, E-mail: cxzhang@snnu.edu.c [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China)

    2011-02-15

    Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m{sup -2} yr{sup -1}. The average deposition rate (76.7 g m{sup -2} yr{sup -1}) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), {approx}10% of the settled dusts having size <2.6, {approx}30% having size <10.5, and >70% having size <30 {mu}m; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: High atmospheric dust deposition rate in Xi'an, Shaanxi, China. Coal-burning power plan being a major source of particulate matter in Xi'an area. High levels of toxic elements in the settled dusts. Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China.

  5. Gas phase deposition of oxide and metal-oxide coatings on fuel particles

    International Nuclear Information System (INIS)

    Patokin, A.P.; Khrebtov, V.L.; Shirokov, B.M.

    2008-01-01

    Production processes and properties of oxide (Al 2 O 3 , ZrO 2 ) and metal-oxide (Mo-Al 2 O 3 , Mo-ZrO 2 , W-Al 2 O 3 , W-ZrO 2 ) coatings on molybdenum substrates and uranium dioxide fuel particles were investigated. It is shown that the main factors that have an effect on the deposition rate, density, microstructure and other properties of coatings are the deposition temperature, the ratio of H 2 and CO 2 flow rates, the total reactor pressure and the ratio of partial pressures of corresponding metal chlorides during formation of metal-oxide coatings

  6. Deposition of inhaled particles in the respiratory tract as a function of age at exposure

    International Nuclear Information System (INIS)

    Thomas, R.G.; Healy, J.W.

    1985-01-01

    A respiratory tract deposition model was developed that would accommodate age 1 month to adulthood as an initial step in calculating radiation dose following inhalation during environmental exposures. The approach to changing respiratory tract and physiological parameters to be applicable to children was to derive an analytical function describing the ratio of the child value to the value for a reference adult with the desired characteristics. A computer program was written to carry out the tracing of airflow through the respiratory tract and deposition in each of the sections for monodispersed particles of known density and diameter. 7 references

  7. Mineralogical composition of boiler fouling and slagging deposits and their relation to fly ashes: the case of Kardia power plant.

    Science.gov (United States)

    Kostakis, George

    2011-01-30

    Slagging and fouling deposits from a pulverized lignite fired steam generating unit of the Kardia power plant (West Macedonia, Greece) were mineralogically investigated. The structure and cohesion of these deposits varied, usually depending on the level height of the boiler unit where they were formed. Some of the deposits had complex phase composition. The dominant components of the deposits of the burner zone and of the lower and intermediate boiler zones were the amorphous, anhydrite and hematite, while those of the highest levels contained amorphous, and anhydrite. Furthermore, in deposits formed in various other boiler areas gehlenite, anorthite, diopside, quartz, Ca(2)SiO(4), brownmillerite and other crystalline phases were also identified, usually in low amounts or in traces. The major part of the phases constituting the deposits were formed in the boiler, since only a minor part derived from the unreacted minerals present in lignite. Anhydrite was generated from the reaction of SO(2) with CaO formed mainly by the calcination of calcite as well as from dehydration of gypsum contained in lignite, while hematite was produced mainly from the oxidation of pyrite. The calcium-containing silicates formed in the boiler were mainly the products of reactions between CaO and minerals contained in the lignite. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Flow regime and deposition pattern of evaporating binary mixture droplet suspended with particles.

    Science.gov (United States)

    Zhong, Xin; Duan, Fei

    2016-02-01

    The flow regimes and the deposition pattern have been investigated by changing the ethanol concentration in a water-based binary mixture droplet suspended with alumina nanoparticles. To visualize the flow patterns, Particle Image Velocimetry (PIV) has been applied in the binary liquid droplet containing the fluorescent microspheres. Three distinct flow regimes have been revealed in the evaporation. In Regime I, the vortices and chaotic flows are found to carry the particles to the liquid-vapor interface and to promote the formation of particle aggregation. The aggregates move inwards in Regime II as induced by the Marangoni flow along the droplet free surface. Regime III is dominated by the drying of the left water and the capillary flow driving particles radially outward is observed. The relative weightings of Regimes I and II, which are enhanced with an increasing load of ethanol, determine the motion of the nanoparticles and the formation of the final drying pattern.

  9. Influence of the Chernobyl accident on radioactivity of fuel peat and peat ash in Finland

    International Nuclear Information System (INIS)

    Mustonen, R.; Salonen, S.; Itkonen, A.

    1988-04-01

    The accident at the Chernobyl nuclear power plant in April 1986 caused very uneven deposition of radionuclides in Finland. The deposited radionuclides were measured in relative high concentrations in fuel peat and especially in peat ash. The radionuclide concentrations were measured at six peat-fired power plants in different parts of Finland throughout the heating season 1986-87. Also evaporation of different radionuclides in peat combustion and their condensation on fly ash particles were studied at four power plants. The 137 Cs-concentrations in compiled peat samples varied between 30 and 3600 Bq kg -1 dry weight and in ash samples between 600 and 68000 Bq kg -1 . Differences in radionuclide concentrations between the power plants were great and also the radionuclide composition in fuel peat varied regionally. The 137 Cs-concentrations of the fly ash after the ash precipitators varied between 12000 and 120000 Bq kg -1 and fly ash emissions varied from 17 to 1100 mg m -3 , depending on the power plant and the load of the boiler. High radioactivity concentrations in precipitator ash caused some restrictions to the utilization of peat ash for various purposes

  10. Use of high ash fuel in diesel power plants II; Korkean tuhkapitoisuuden omaavan polttoaineen kaeyttoe dieselvoimaloissa II

    Energy Technology Data Exchange (ETDEWEB)

    Vestergren, R; Normen, E; Hellen, G [Wartsila Diesel International Ltd Oy, Vaasa (Finland); and others

    1997-10-01

    Heavy fuel oils containing a large amount of ash are used in some geographically restricted areas. The ash components can cause problems with deposit formation and hot corrosion, leading to burned exhaust gas valves in some diesel engines. The LIEKKI 2 programs Use of high ash fuel in diesel power plants, Part I and II, have been initiated to clarify the mechanisms of deposit formation, and start and propagation of hot corrosion. The aim is to get enough knowledge to enable the development of the Waertsilae diesel engines to be able to handle heavy fuels with a very high ash content. The chemistry during combustion has been studied. The chemical and physical properties of the particles in the exhaust gas, of the deposits, and of exhaust valves have been investigated. Exhaust gas particle measurements have been performed when running on high ash fuel, both with and without deposit modifying fuel additive. Theories for the mechanisms mentioned above have been developed. On the practical side two long time field tests are going on, one with an ash/deposit modifying fuel additive (vanadium chemistry alteration), one with fuel water washing (sodium removal). Seven different reports have been written. (orig.)

  11. Quantifying particulate matter deposition in Niwot Ridge, Colorado: Collection of dry deposition using marble inserts and particle imaging using the FlowCAM

    Science.gov (United States)

    Goss, Natasha R.; Mladenov, Natalie; Seibold, Christine M.; Chowanski, Kurt; Seitz, Leslie; Wellemeyer, T. Barret; Williams, Mark W.

    2013-12-01

    Atmospheric wet and dry deposition are important sources of carbon for remote alpine lakes and soils. The carbon inputs from dry deposition in alpine National Atmospheric Deposition Program (NADP) collectors, including aeolian dust and biological material, are not well constrained due to difficulties in retaining particulate matter in the collectors. Here, we developed and tested a marble insert for dry deposition collection at the Niwot Ridge Long Term Ecological Research Station (NWT LTER) Soddie site (3345 m) between 24 May and 8 November 2011. We conducted laboratory tests of the insert's effect on particulate matter (PM) mass and non-purgeable organic carbon (DOC) and found that the insert did not significantly change either measurement. Thus, the insert may enable dry deposition collection of PM and DOC at NADP sites. We then developed a method for enumerating the collected wet and dry deposition with the Flow Cytometer and Microscope (FlowCAM), a dynamic-image particle analysis tool. The FlowCAM has the potential to establish morphology, which affects particle settling and retention, through particle diameter and aspect ratio. Particle images were used to track the abundance of pollen grains over time. Qualitative image examination revealed that most particles were biological in nature, such as intact algal cells and pollen. Dry deposition loading to the Soddie site as determined by FlowCAM measurements was highly variable, ranging from 100 to >230 g ha-1 d-1 in June-August 2011 and peaking in late June. No significant difference in diameter or aspect ratio was found between wet and dry deposition, suggesting fundamental similarities between those deposition types. Although FlowCAM statistics and identification of particle types proved insightful, our total-particle enumeration method had a high variance and underestimated the total number of particles when compared to imaging of relatively large volumes (60-125 mL) from a single sample. We recommend use of

  12. Monte Carlo charged-particle tracking and energy deposition on a Lagrangian mesh.

    Science.gov (United States)

    Yuan, J; Moses, G A; McKenty, P W

    2005-10-01

    A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted mesh cells, particle relocation on the moving mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.

  13. Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

    Science.gov (United States)

    Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

    2013-06-01

    Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. Copyright © 2012 Wiley Periodicals, Inc.

  14. Detection of Soot Using a Resistivity Sensor Device Employing Thermophoretic Particle Deposition

    Directory of Open Access Journals (Sweden)

    Doina Lutic

    2010-01-01

    Full Text Available Results are reported for thermophoretic deposition of soot particles on resistivity sensors as a monitoring technique for diesel exhaust particles with the potential of improved detection limit and sensitivity. Soot with similar characteristics as from diesel exhausts was generated by a propane flame and diluted in stages. The soot in a gas flow at 240–270C∘ was collected on an interdigitated electrode structure held at a considerably lower temperature, 105–125C∘. The time delay for reaching measurable resistance values, the subsequent rate, and magnitude of resistance decrease were a function of the distance between the fingers in the electrodes and the degree of dilution of the soot containing flow. Soot deposition and subsequent removal by heating the sensor support was also performed in a real diesel exhaust. Good similarities between the behavior in our laboratory system and the real diesel exhaust were noticed.

  15. Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

    Energy Technology Data Exchange (ETDEWEB)

    Uudeküll, Peep, E-mail: peep.uudekull@ut.ee [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kozlova, Jekaterina; Mändar, Hugo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Link, Joosep [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Sihtmäe, Mariliis [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Käosaar, Sandra [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Blinova, Irina; Kasemets, Kaja; Kahru, Anne [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Stern, Raivo [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Tätte, Tanel [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kukli, Kaupo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Tamm, Aile [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia)

    2017-05-01

    Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

  16. Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

    International Nuclear Information System (INIS)

    Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

    2017-01-01

    Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

  17. Wildland fire ash: future research directions

    Science.gov (United States)

    Bodí, Merche B.; Martins, Deborah A.; Cerdà, Artemi; Balfour, Victoria N.; Santin, Cristina; Doerr, Stefan H.; Pereira, Paulo; Mataix-Solera, Jorge

    2014-05-01

    Ash is a key component of the forest fires affected land (Cerdà, 1998; Bodí et al., 2011; Pereira et al., 2013a). Ash controls the hydrological processes and determines the water repellency (Dlapa et al., 2012) and the infiltration rates (Cerdà and Doerr, 2008;). Moreover, ash is the key factor on runoff initiation and then on the soil erosion. Little is known about the impact of ash in different ecosystems, but during the last decade a substantial increase in the papers that show the role of ash in the Earth and Soil System were published (Bodí et al., 2012; Pereira et al., 2013b).. Ash is being found as the key component of the post-fire pedological, geomorphological and hydrological response after forest fires (Fernández et al., 2012; Martín et al., 2012; Bodí et al., 2013; Guénon et al., 2013; Pereira et al., 2013c). A recent State-of-the-Art review about wildland fire ash (Bodí et al., 2014) compiles the knowledge regarding the production, composition and eco-hydro-geomorphic effects of wildland fire ash. In the present paper we indicate the knowledge gaps detected and suggest topics that need more research effort concerning: i) data collection and analysis techniques: a) To develop standardized sampling techniques that allow cross comparison among sites and avoid inclusion of the underlying soil unless the burned surface soil forms part of the ash layer, b) To develop standardized methods to define and characterize ash, including its color, physical properties such as particle size distribution or density, proportion of pyrogenic C, chemical and biological reactivity and persistence in the environment, c) To validate, calibrate and test measurements collected through remote sensing with on-the-ground measurements. ii) ash production, deposition redistribution and fate: d) To untangle the significance of the effects of maximum temperature reached during combustion versus the duration of heating, e) To understand the production of ash by measuring its

  18. ‘Sticky business’: The influence of streambed periphyton on particle deposition and infiltration

    Science.gov (United States)

    Salant, Nira L.

    2011-03-01

    Strong feedbacks exist between physical and ecological components of aquatic systems. Aquatic plants can alter flow and sedimentation patterns, in turn influencing habitat condition and organism responses. In this study, I investigate the interactions between streambed periphyton, particle deposition and infiltration, and flow hydraulics to determine the influence of these organisms on the local environment. In a series of flume experiments, I measured the effects of two contrasting forms of periphyton at several densities and growth stages on near-bed hydraulics, particle loss from the water column, surface deposition, and subsurface infiltration. Data show that periphyton assemblages altered the rate and quantity of particle deposition via several mechanisms, including shear stress modification, surface adhesion, and bed clogging. Although trends varied for different size classes within a suspension of fine sediment, diatoms and algae had distinctly different effects on hydraulics, deposition, and infiltration. In general, diatoms increased the rate of decline in suspended particle concentrations relative to non-periphyton surfaces by reducing shear stresses and enhancing surface deposition via adhesion. Increases in diatom biomass, however, reduced the quantity and depth of particle infiltration, presumably by clogging interstitial pore spaces, in turn lowering rates of concentration decline. In contrast, all algal growth stages had slower or similar rates of concentration decline compared to non-periphyton conditions, due to partial clogging by high biomass and a lack of adhesion at the bed surface. Clogging effects were counteracted at later growth stages, however, as late-stage algal structures increased shear stresses and downward advection, in turn increasing amounts of infiltration. Compiled data from several field studies and experiments demonstrate a positive relation between periphyton biomass and inorganic mass, but also show a wide range in the

  19. Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic

    Directory of Open Access Journals (Sweden)

    M. van der Does

    2016-11-01

    Full Text Available Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations in particle size of Saharan dust deposition across the Atlantic Ocean, using an array of submarine sediment traps moored along a transect at 12° N. We show that the particle size decreases downwind with increased distance from the Saharan source, due to higher gravitational settling velocities of coarse particles in the atmosphere. Modal grain sizes vary between 4 and 32 µm throughout the different seasons and at five locations along the transect. This is much coarser than previously suggested and incorporated into climate models. In addition, seasonal changes are prominent, with coarser dust in summer and finer dust in winter and spring. Such seasonal changes are caused by transport at higher altitudes and at greater wind velocities during summer than in winter. Also, the latitudinal migration of the dust cloud, associated with the Intertropical Convergence Zone, causes seasonal differences in deposition as the summer dust cloud is located more to the north and more directly above the sampled transect. Furthermore, increased precipitation and more frequent dust storms in summer coincide with coarser dust deposition. Our findings contribute to understanding Saharan dust transport and deposition relevant for the interpretation of sedimentary records for climate reconstructions, as well as for global and regional models for improved prediction of future climate.

  20. Particle resuspension from a multi-layer deposit by turbulent flow

    International Nuclear Information System (INIS)

    Fromentin, A.

    1989-09-01

    The aim of this work was to contribute to the understanding and quantification of particle resuspension from a bed exposed to a turbulent flow. The PARESS experiment has been set up and conducted. Multi-layer deposits of particles were created by allowing aerosols to settle on steel plates under conditions typical of a nuclear reactor containment following a severe accident. These were then exposed to a controlled turbulent airflow (U ∞ =5-25 m/s) in a wind tunnel and the evolution of the resuspension flux as a function of time was measured. The resuspension flux F r decreased with exposure time to the airflow t, according to a power law F r = a.t -b [kg/m 2 .s]. The parameters a and b depend on the flow velocity and the nature of the deposit. A new semi-empirical model, based on the comparison between the distributions of adhesive forces holding the particles on the deposit and aerodynamic forces tending to remove them, has been developed to simulate the stochastic nature of particle resuspension. This model is able to predict the experimentally observed decrease of the resuspension flux as a function of time and its dependence on flow velocity. Based on the results of the PARESS experiment, an empirical global relationship, which ignores the fine effects due to the nature of the different deposits, has been proposed. It appears that the resuspension flux is approximately proportinal to the cube of the flow velocity, and that a pseudo threshold velocity exists below which virtually no resuspension occurs. (author) 57 figs., 1 tab., 79 refs

  1. Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyeong-Ho; Jang, Jin-Nyoung; Hong, MunPyo; Kwon, Kwang-Ho; Park, Hyung-Ho

    2010-01-01

    Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 o C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.

  2. Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor.

    Science.gov (United States)

    Malinowski, Robert; Volpe, Giovanni; Parkin, Ivan P; Volpe, Giorgio

    2018-02-01

    The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner.

  3. A Theoretically Consistent Framework for Modelling Lagrangian Particle Deposition in Plant Canopies

    Science.gov (United States)

    Bailey, Brian N.; Stoll, Rob; Pardyjak, Eric R.

    2018-06-01

    We present a theoretically consistent framework for modelling Lagrangian particle deposition in plant canopies. The primary focus is on describing the probability of particles encountering canopy elements (i.e., potential deposition), and provides a consistent means for including the effects of imperfect deposition through any appropriate sub-model for deposition efficiency. Some aspects of the framework draw upon an analogy to radiation propagation through a turbid medium with which to develop model theory. The present method is compared against one of the most commonly used heuristic Lagrangian frameworks, namely that originally developed by Legg and Powell (Agricultural Meteorology, 1979, Vol. 20, 47-67), which is shown to be theoretically inconsistent. A recommendation is made to discontinue the use of this heuristic approach in favour of the theoretically consistent framework developed herein, which is no more difficult to apply under equivalent assumptions. The proposed framework has the additional advantage that it can be applied to arbitrary canopy geometries given readily measurable parameters describing vegetation structure.

  4. Particle connectedness and cluster formation in sequential depositions of particles: integral-equation theory.

    Science.gov (United States)

    Danwanichakul, Panu; Glandt, Eduardo D

    2004-11-15

    We applied the integral-equation theory to the connectedness problem. The method originally applied to the study of continuum percolation in various equilibrium systems was modified for our sequential quenching model, a particular limit of an irreversible adsorption. The development of the theory based on the (quenched-annealed) binary-mixture approximation includes the Ornstein-Zernike equation, the Percus-Yevick closure, and an additional term involving the three-body connectedness function. This function is simplified by introducing a Kirkwood-like superposition approximation. We studied the three-dimensional (3D) system of randomly placed spheres and 2D systems of square-well particles, both with a narrow and with a wide well. The results from our integral-equation theory are in good accordance with simulation results within a certain range of densities.

  5. Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Joana [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); DaBoit, Kátia [Institute of Environmental Research and Human Development, IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Flores, Deolinda [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Kronbauer, Marcio A. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Silva, Luis F.O., E-mail: felipeqma@hotmail.com [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Environmental Science and Nanotechnology Department, Catarinense Institute of Environmental Research and Human Development, IPADHC, Capivari de Baixo, Santa Catarina (Brazil)

    2013-05-01

    The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis. - Highlights: ► We examine changes in the level of ultrafine and nanoparticles of coal mining. ► Increasing geochemical information will increase human health information in this area. ► Electron bean and Tof-SIMS increase area information.

  6. Measurement of the deposition of aerosol particles to skin, hair and clothing

    International Nuclear Information System (INIS)

    Bell, K.F.

    1999-01-01

    In the event of a nuclear accident, there are several routes whereby human populations may receive a radioactive dose from material released to the environment. The dose from radioactive aerosol deposited onto the surfaces of the human body has previously been estimated by assuming that aerosol deposition velocities (defined as the flux of aerosol onto a surface divided by the aerosol concentration above the surface) onto human body surfaces are similar to the values for inanimate surfaces. However, Jones (1990) modelled the effects on health of fallout material deposited on skin and clothing and found that the number of early deaths from skin dose was sensitively dependent on aerosol deposition velocity. He also pointed out that there was a lack of experimentally derived data on aerosol deposition velocities to human body surfaces and that the above mentioned assumption may not be valid. The purpose of the present work is to measure aerosol deposition velocities onto human body surfaces, the resultant data to allow more accurate nuclear accident consequence modelling. Aerosol deposition velocities onto human body surfaces in simulated indoor conditions have been measured by releasing tracer aerosols of three mean particle diameters (2.6, 6.2 and 9.2μm) into a test chamber containing volunteers. The skin, hair and clothing of the volunteers were sampled and analysed for deposited aerosol by Neutron Activation Analysis. Aerosol deposition velocities onto skin in the range 1.3 - 15 x 10 -3 ms -1 were recorded, values which are approximately an order of magnitude higher than the equivalent values onto the floor of the test room. These values suggest that the exposure route of radioactive aerosol particles deposited on the skin may be more significant than hitherto had been assumed. The possible mechanisms leading to this relatively high deposition were investigated experimentally and the results suggested that a combination of factors such as the body's electrostatic

  7. Impact of Volcanic Ash on Road and Airfield Surface Skid Resistance

    Directory of Open Access Journals (Sweden)

    Daniel M. Blake

    2017-08-01

    Full Text Available Volcanic ash deposited on paved surfaces during volcanic eruptions often compromises skid resistance, which is a major component of safety. We adopt the British pendulum test method in laboratory conditions to investigate the skid resistance of road asphalt and airfield concrete surfaces covered by volcanic ash sourced from various locations in New Zealand. Controlled variations in ash characteristics include type, depth, wetness, particle size and soluble components. We use Stone Mastic Asphalt (SMA for most road surface experiments but also test porous asphalt, line-painted road surfaces, and a roller screed concrete mix used for airfields. Due to their importance for skid resistance, SMA surface macrotexture and microtexture are analysed with semi-quantitative image analysis, microscopy and a standardised sand patch volumetric test, which enables determination of the relative effectiveness of different cleaning techniques. We find that SMA surfaces covered by thin deposits (~1 mm of ash result in skid resistance values slightly lower than those observed on wet uncontaminated surfaces. At these depths, a higher relative soluble content for low-crystalline ash and a coarser particle size results in lower skid resistance. Skid resistance results for relatively thicker deposits (3–5 mm of non-vesiculated basaltic ash are similar to those for thin deposits. There are similarities between road asphalt and airfield concrete, although there is little difference in skid resistance between bare airfield surfaces and airfield surfaces covered by 1 mm of ash. Based on our findings, we provide recommendations for maintaining road safety and effective cleaning techniques in volcanic ash environments.

  8. Slagging and fouling evaluation of PC-fired boilers using AshPro{sup SM}

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhanhua; Iman, Felicia; Lu, Pisi [SmartBurn, LLC, Madison, WI (United States)

    2013-07-01

    SmartBurn {sup registered} applied AshPro{sup SM} model to two 512 MW Tangential-fired (T-fired) boilers firing US western sub- bituminous coals to evaluate the boiler slagging behaviors with different operating conditions and OFA. The boiler convective pass fouling behaviors with three different coals were also evaluated. The slagging evaluation results indicate that the OFA configuration and air flow distribution have dramatically impacts on the ash impaction rates and slagging patterns on the furnace walls. Deposit growth and strength vary at the different regions of the furnace walls. The fouling evaluation reveals that the tube bank configuration, the amount of incoming ash, the profiles of flue gas temperature, velocity, and species all have significant impacts on fouling deposit formation, growth, and strength development. In addition, the varying ash particle sizes and chemical compositions from different coals also play important roles on the fouling deposit strength development and removal. The investigation demonstrated that AshPro{sup SM} model can be used to evaluate localized slagging and fouling problems that are related to specific boiler configuration and operating conditions. It can be used to identify the major causes of ash deposition and can guide changes in boiler operation.

  9. Numerical simulation of fly-ash transport in three sands of different particle-size distributions using HYDRUS-1D

    Czech Academy of Sciences Publication Activity Database

    Kodešová, R.; Kapička, Aleš; Lebeda, J.; Grison, Hana; Kočárek, M.; Petrovský, Eduard

    2011-01-01

    Roč. 59, č. 3 (2011), s. 206-216 ISSN 0042-790X R&D Projects: GA AV ČR IAA300120701 Institutional research plan: CEZ:AV0Z30120515 Keywords : sand * fly-ash migration * magnetic susceptibility * numerical simulation * attachment /detachment concept * filtration theory Subject RIV: DK - Soil Contamination ; De-contamination incl. Pesticides Impact factor: 0.340, year: 2011

  10. Absorption by airborne and deposited particles in the 8-13 micrometer range

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, K; Grassl, H

    1975-01-01

    The absorption of radiation by natural aerosol particles was measured in the 8 to 13 micrometer wavelength interval. A comparison was made between an in situ method and measurements of particles of deposited form. The results are in agreement to about 30 percent. The main feature of aerosol absorption within the infrared window is a strong absorption peak near 9 micrometers caused by sulfate or quartz particles present in all continental aerosol types. Consequences for the atmospheric heat balance are clear sky cooling rates growing from about 2 per cent in the tropics to about 20 per cent of the total cooling in arctic regions under normal conditions, additionally increasing with increasing relative humidity.

  11. Anisotropic Metal Deposition on TiO2 Particles by Electric-Field-Induced Charge Separation.

    Science.gov (United States)

    Tiewcharoen, Supakit; Warakulwit, Chompunuch; Lapeyre, Veronique; Garrigue, Patrick; Fourier, Lucas; Elissalde, Catherine; Buffière, Sonia; Legros, Philippe; Gayot, Marion; Limtrakul, Jumras; Kuhn, Alexander

    2017-09-11

    Deposition of metals on TiO 2 semiconductor particles (M-TiO 2 ) results in hybrid Janus objects combining the properties of both materials. One of the techniques proposed to generate Janus particles is bipolar electrochemistry (BPE). The concept can be applied in a straightforward way for the site-selective modification of conducting particles, but is much less obvious to use for semiconductors. Herein we report the bulk synthesis of anisotropic M-TiO 2 particles based on the synergy of BPE and photochemistry, allowing the intrinsic limitations, when they are used separately, to be overcome. When applying electric fields during irradiation, electrons and holes can be efficiently separated, thus breaking the symmetry of particles by modifying them selectively and in a wireless way on one side with either gold or platinum. Such hybrid materials are an important first step towards high-performance designer catalyst particles, for example for photosplitting of water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating.

    Science.gov (United States)

    Koivisto, Antti J; Jensen, Alexander C Ø; Kling, Kirsten I; Kling, Jens; Budtz, Hans Christian; Koponen, Ismo K; Tuinman, Ilse; Hussein, Tareq; Jensen, Keld A; Nørgaard, Asger; Levin, Marcus

    2018-01-05

    Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO 2 )-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m 3 test chamber while measuring concentrations of 5.6nm to 31μm-size particles and volatile organic compounds (VOC), as well as particle deposition onto room surfaces and on the spray gun user hand. The particle emission and deposition rates were quantified using aerosol mass balance modelling. The geometric mean particle number emission rate was 1.9×10 10 s -1 and the mean mass emission rate was 381μgs -1 . The respirable mass emission-rate was 65% lower than observed for the entire measured size-range. The mass emission rates were linearly scalable (±ca. 20%) to the process duration. The particle deposition rates were up to 15h -1 for deposited particles consisted of mainly TiO 2 , TiO 2 mixed with Cl and/or Ag, TiO 2 particles coated with carbon, and Ag particles with size ranging from 60nm to ca. 5μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  13. Deposition and reentrainment of Brownian particles in porous media under unfavorable chemical conditions: some concepts and applications.

    Science.gov (United States)

    Hahn, Melinda W; O'Meliae, Charles R

    2004-01-01

    The deposition and reentrainment of particles in porous media have been examined theoretically and experimentally. A Brownian Dynamics/Monte Carlo (MC/BD) model has been developed that simulates the movement of Brownian particles near a collector under "unfavorable" chemical conditions and allows deposition in primary and secondary minima. A simple Maxwell approach has been used to estimate particle attachment efficiency by assuming deposition in the secondary minimum and calculating the probability of reentrainment. The MC/BD simulations and the Maxwell calculations support an alternative view of the deposition and reentrainment of Brownian particles under unfavorable chemical conditions. These calculations indicate that deposition into and subsequent release from secondary minima can explain reported discrepancies between classic model predictions that assume irreversible deposition in a primary well and experimentally determined deposition efficiencies that are orders of magnitude larger than Interaction Force Boundary Layer (IFBL) predictions. The commonly used IFBL model, for example, is based on the notion of transport over an energy barrier into the primary well and does not address contributions of secondary minimum deposition. A simple Maxwell model based on deposition into and reentrainment from secondary minima is much more accurate in predicting deposition rates for column experiments at low ionic strengths. It also greatly reduces the substantial particle size effects inherent in IFBL models, wherein particle attachment rates are predicted to decrease significantly with increasing particle size. This view is consistent with recent work by others addressing the composition and structure of the first few nanometers at solid-water interfaces including research on modeling water at solid-liquid interfaces, surface speciation, interfacial force measurements, and the rheological properties of concentrated suspensions. It follows that deposition under these

  14. Laboratory studies of immersion and deposition mode ice nucleation of ozone aged mineral dust particles

    Directory of Open Access Journals (Sweden)

    Z. A. Kanji

    2013-09-01

    Full Text Available Ice nucleation in the atmosphere is central to the understanding the microphysical properties of mixed-phase and cirrus clouds. Ambient conditions such as temperature (T and relative humidity (RH, as well as aerosol properties such as chemical composition and mixing state play an important role in predicting ice formation in the troposphere. Previous field studies have reported the absence of sulfate and organic compounds on mineral dust ice crystal residuals sampled at mountain top stations or aircraft based measurements despite the long-range transport mineral dust is subjected to. We present laboratory studies of ice nucleation for immersion and deposition mode on ozone aged mineral dust particles for 233 T ns are reported and observed to increase as a function of decreasing temperature. We present first results that demonstrate enhancement of the ice nucleation ability of aged mineral dust particles in both the deposition and immersion mode due to ageing. We also present the first results to show a suppression of heterogeneous ice nucleation activity without the condensation of a coating of (inorganic material. In immersion mode, low ozone exposed Ka particles showed enhanced ice activity requiring a median freezing temperature of 1.5 K warmer than that of untreated Ka, whereas high ozone exposed ATD particles showed suppressed ice nucleation requiring a median freezing temperature of 3 K colder than that of untreated ATD. In deposition mode, low exposure Ka had ice active fractions of an order of magnitude higher than untreated Ka, whereas high ozone exposed ATD had ice active fractions up to a factor of 4 lower than untreated ATD. From our results, we derive and present parameterizations in terms of ns(T that can be used in models to predict ice nuclei concentrations based on available aerosol surface area.

  15. Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler

    Directory of Open Access Journals (Sweden)

    Darrah K. Sleeth

    2016-03-01

    Full Text Available Extrathoracic deposition of inhaled particles (i.e., in the head and throat is an important exposure route for many hazardous materials. Current best practices for exposure assessment of aerosols in the workplace involve particle size selective sampling methods based on particle penetration into the human respiratory tract (i.e., inhalable or respirable sampling. However, the International Organization for Standardization (ISO has recently adopted particle deposition sampling conventions (ISO 13138, including conventions for extrathoracic (ET deposition into the anterior nasal passage (ET1 and the posterior nasal and oral passages (ET2. For this study, polyurethane foam was used as a collection substrate inside an inhalable aerosol sampler to provide an estimate of extrathoracic particle deposition. Aerosols of fused aluminum oxide (five sizes, 4.9 µm–44.3 µm were used as a test dust in a low speed (0.2 m/s wind tunnel. Samplers were placed on a rotating mannequin inside the wind tunnel to simulate orientation-averaged personal sampling. Collection efficiency data for the foam insert matched well to the extrathoracic deposition convention for the particle sizes tested. The concept of using a foam insert to match a particle deposition sampling convention was explored in this study and shows promise for future use as a sampling device.

  16. Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler.

    Science.gov (United States)

    Sleeth, Darrah K; Balthaser, Susan A; Collingwood, Scott; Larson, Rodney R

    2016-03-07

    Extrathoracic deposition of inhaled particles (i.e., in the head and throat) is an important exposure route for many hazardous materials. Current best practices for exposure assessment of aerosols in the workplace involve particle size selective sampling methods based on particle penetration into the human respiratory tract (i.e., inhalable or respirable sampling). However, the International Organization for Standardization (ISO) has recently adopted particle deposition sampling conventions (ISO 13138), including conventions for extrathoracic (ET) deposition into the anterior nasal passage (ET₁) and the posterior nasal and oral passages (ET₂). For this study, polyurethane foam was used as a collection substrate inside an inhalable aerosol sampler to provide an estimate of extrathoracic particle deposition. Aerosols of fused aluminum oxide (five sizes, 4.9 µm-44.3 µm) were used as a test dust in a low speed (0.2 m/s) wind tunnel. Samplers were placed on a rotating mannequin inside the wind tunnel to simulate orientation-averaged personal sampling. Collection efficiency data for the foam insert matched well to the extrathoracic deposition convention for the particle sizes tested. The concept of using a foam insert to match a particle deposition sampling convention was explored in this study and shows promise for future use as a sampling device.

  17. Investigation of the particle size distribution and particle density characteristics of Douglas fir hogged fuel fly ash collected under known combustion conditions. Technical Progress Report No. 2

    Energy Technology Data Exchange (ETDEWEB)

    Lang, A.J.; Junge, D.C.

    1978-12-01

    The increased interest in wood as a fuel source, coupled with the increasing demand to control the emission generated by wood combustion, has created a need for information characterizing the emissions that occur for given combustion conditions. This investigation characterizes the carbon char and inorganic fly ash size and density distribution for each of thirty-eight Douglas fir bark samples collected under known conditions of combustion.

  18. Particle size distribution of ashes and the behaviour of metals when firing Salix in a circulating fluidized bed boiler (CFB); Askans partikelfraktionsfoerdelning och metallernas beteende vid eldning av Salix i en CFB-panna

    Energy Technology Data Exchange (ETDEWEB)

    Sfiris, G; Johansson, A [Vattenfall Utveckling AB, Stockholm (Sweden); Valmari, T; Kauppinen, E; Pyykoenen, J; Lyyraenen, J [VTT Technical Research Centre of Finland, Espoo (Finland)

    1999-07-01

    This project is part of the Ash Recovery Programme aimed at establishing the environmental, technical and financial preconditions for returning wood ash to the forest. The programme is funded jointly by NUTEK, Sydkraft and Vattenfall. This report summarises the results of the experimental and modelling work to study the behaviour of the metals (especially Cd and K), after burning Salix in a 3-12 MW Circulating Fluidized Bed (CFB) boiler. The purpose of the study was to determine, using the experimental data, where cadmium and potassium condense, on what size particles they condense, and the decisive parameters governing these processes. Measurements of the fly ash particle size distribution carried out with a Berner Low Pressure Impactor (BLPI), coupled to a pre-cyclone. Samples were collected from three points: in the convection path at 650 deg C, after the convection path but before the secondary cyclone (160 deg C), and after the bag house (150 deg C). Wet chemical sampling was made for Cd, K, Zn and Pb, with three types of sampling equipment: collection of both particles and gas, collection of particles only, and analysis of the gas phase only. Analysis was made of samples from two places in the convection path (650 deg C and 250 deg C). Samples of bed material, bottom ash and fly ash have been subjected to scanning electron microscopy (SEM), and in addition a few fly ash particles, sampled after the convection path, were subjected to energy dispersive X-ray analysis (EDX). Based on experimental results, modelling work was carried out with an equilibrium model and with a general aerosol computer model ABC (Aerosol Behaviour in Combustion)

  19. Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

    Science.gov (United States)

    Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

    2018-06-01

    Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

  20. Advection diffusion model for particles deposition in Rayleigh-Benard turbulent flows

    International Nuclear Information System (INIS)

    Oresta, P.; Lippolis, A.; Verzicco, R.; Soldati, A.

    2005-01-01

    In this paper, Direct Numerical Simulation (DNS) and Lagrangian Particle Tracking are used to precisely investigate the turbulent thermally driven flow and particles dispersion in a closed, slender cylindrical domain. The numerical simulations are carried out for Rayleigh (Ra) and Prandtl numbers (Pr) equal to Ra = 2X10 8 and Pr = 0.7, considering three sets of particles with Stokes numbers, based on Kolmogorov scale, equal to St k 1.3, St k 0.65 and St k = 0.13. This data are used to calculate a priori the drift velocity and the turbulent diffusion coefficient for the Advection Diffusion model. These quantities are function of the Stokes, Froude, Rayleigh and Prandtl numbers only. One dimensional, time dependent, Advection- Diffusion Equation (ADE) is presented to predict particles deposition in Rayleigh-Benard flow in the cylindrical domain. This archetype configuration models flow and aerosol dynamics, produced in case of accident in the passive containment cooling system (PCCS) of a nuclear reactor. ADE results show a good agreement with DNS data for all the sets of particles investigated. (author)

  1. Radial transport processes as a precursor to particle deposition in drinking water distribution systems.

    Science.gov (United States)

    van Thienen, P; Vreeburg, J H G; Blokker, E J M

    2011-02-01

    Various particle transport mechanisms play a role in the build-up of discoloration potential in drinking water distribution networks. In order to enhance our understanding of and ability to predict this build-up, it is essential to recognize and understand their role. Gravitational settling with drag has primarily been considered in this context. However, since flow in water distribution pipes is nearly always in the turbulent regime, turbulent processes should be considered also. In addition to these, single particle effects and forces may affect radial particle transport. In this work, we present an application of a previously published turbulent particle deposition theory to conditions relevant for drinking water distribution systems. We predict quantitatively under which conditions turbophoresis, including the virtual mass effect, the Saffman lift force, and the Magnus force may contribute significantly to sediment transport in radial direction and compare these results to experimental observations. The contribution of turbophoresis is mostly limited to large particles (>50 μm) in transport mains, and not expected to play a major role in distribution mains. The Saffman lift force may enhance this process to some degree. The Magnus force is not expected to play any significant role in drinking water distribution systems. © 2010 Elsevier Ltd. All rights reserved.

  2. Total deposition of inhaled particles related to age: comparison with age-dependent model calculations

    International Nuclear Information System (INIS)

    Becquemin, M.H.; Bouchikhi, A.; Yu, C.P.; Roy, M.

    1991-01-01

    To compare experimental data with age-dependent model calculations, total airway deposition of polystyrene aerosols (1, 2.05 and 2.8 μm aerodynamic diameter) was measured in ten adults, twenty children aged 12 to 15 years, ten children aged 8 to 12, and eleven under 8 years old. Ventilation was controlled, and breathing patterns were appropriate for each age, either at rest or at light exercise. Individually, deposition percentages increased with particle size and also from rest to exercise, except in children under 12 years, in whom they decreased from 20-21.5 to 14-14.5 for 1 μm particles and from 36.8-36.9 to 32.2-33.1 for 2.05 μm particles. Comparisons with the age-dependent model showed that, at rest, the observed data concerning children agreed with those predicted and were close to the adults' values, when the latter were higher than predicted. At exercise, child data were lower than predicted and lower than adult experimental data, when the latter agreed fairly well with the model. (author)

  3. Advances in Thermal Spray Deposition of Billets for Particle Reinforced Light Metals

    International Nuclear Information System (INIS)

    Wenzelburger, Martin; Zimmermann, Christian; Gadow, Rainer

    2007-01-01

    Forming of light-metals in semi-solid state offers some advantages like low process temperatures, improved mould durability, good flow behavior and fine, globular microstructure of the final material. By the introduction of ceramic particles, increased elastic modulus and yield strength as well as wear resistance and creep behavior can be obtained. By semi-solid forging or semi-solid casting, particle reinforced metals (PRM) can be produced with improved matrix microstructure and beneficial forming process parameters compared to conventional MMC manufacturing techniques. The production of this kind of light metal matrix composites requires the supply of dense semi-finished parts with well defined volume fractions of homogeneously distributed particulate reinforcement. A manufacturing method for cylindrical light metal billets is described that applies thermal spraying as a build-up process for simultaneous deposition of matrix and reinforcement phase with cored wires as spraying material. Thermal spraying leads to small grain sizes and prevents dendrite formation. However, long process cycle times lead to billet heating and recrystallization of the matrix microstructure. In order to preserve small grain sizes that enable semi-solid forming, the thermal spraying process was analyzed by in-flight particle analysis and thermography. As a consequence, the deposition process was optimized by adaptation of the thermal spraying parameters and by application of additional cooling, leading to lower billet temperatures and finer PRM billet microstructure

  4. Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

    Science.gov (United States)

    Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

    2015-06-03

    The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation.

  5. In-flight monitoring of particle deposition in the environmental control systems of commercial airliners in China

    Science.gov (United States)

    Cao, Qing; Xu, Qiuyu; Liu, Wei; Lin, Chao-Hsin; Wei, Daniel; Baughcum, Steven; Norris, Sharon; Chen, Qingyan

    2017-04-01

    Severe air pollution and low on-time performance of commercial flights in China could increase particle deposition in the environmental control systems (ECSs) of commercial airliners. The particles deposited in the ECSs could negatively affect the performance of the airplanes. In addition, particles that penetrate into the aircraft cabin could adversely impact the health of passengers and crew members. This investigation conducted simultaneous measurements of particle mass concentration and size distribution inside and outside the cabin during 64 commercial flights of Boeing 737 and Airbus 320 aircraft departing from or arriving at Tianjin Airport in China. The results showed that the PM2.5 mass concentration deposition in the ECSs of these airplanes ranged from 50% to 90%, which was much higher than that measured in an airplane with a ground air-conditioning unit. The average deposition rates of particles with diameters of 0.5-1 μm, 1-2 μm, 2-5 μm, 5-10 μm, and >10 μm were 89 ± 8%, 85 ± 13%, 80 ± 13%, 73 ± 15%, and 80 ± 14%, respectively. The in-flight measurement results indicated that the particle concentration in the breathing zone was higher than that in the air-supply zone, which implies a significant contribution by particles in the interior of the cabin. Such particles come from human emissions or particle resuspension from interior surfaces.

  6. Facile Deposition of Ultrafine Silver Particles on Silicon Surface Not Submerged in Precursor Solutions for Applications in Antireflective Layer

    Directory of Open Access Journals (Sweden)

    Bing Jiang

    2014-01-01

    Full Text Available Using a facile deposition method, the ultrafine silver particles are successfully deposited on the Si surface that is not submerged in precursor solutions. The ultrafine silver particles have many advantages, such as quasiround shape, uniformity in size, monodisperse distribution, and reduction of agglomeration. The internal physical procedure in the deposition is also investigated. The results show that there are more particles on the rough Si surface due to the wetting effect of solid-liquid interface. The higher concentration of ethanol solvent can induce the increase of quantity and size of particles on Si surface not in solutions. The ultrafine particles can be used to prepare porous Si antireflective layer in solar cell applications.

  7. Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma

    Science.gov (United States)

    McCarthy, K. J.; Tamura, N.; Combs, S. K.; Panadero, N.; Ascabíbar, E.; Estrada, T.; García, R.; Hernández Sánchez, J.; López Fraguas, A.; Navarro, M.; Pastor, I.; Soleto, A.; TJ-II Team

    2017-10-01

    A cryogenic pellet injector (PI) and tracer encapsulated solid pellet (TESPEL) injector system has been operated in combination on the stellarator TJ-II. This unique arrangement has been created by piggy-backing a TESPEL injector onto the backend of a pipe-gun-type PI. The combined injector provides a powerful new tool for comparing ablation and penetration of polystyrene TESPEL pellets and solid hydrogen pellets, as well as for contrasting subsequent pellet particle deposition and plasma perturbation under analogous plasma conditions. For instance, a significantly larger increase in plasma line-averaged electron density, and electron content, is observed after a TESPEL pellet injection compared with an equivalent cryogenic pellet injection. Moreover, for these injections from the low-magnetic-field side of the plasma cross-section, TESPEL pellets deposit electrons deeper into the plasma core than cryogenic pellets. Finally, the physics behind these observations and possible implications for pellet injection studies are discussed.

  8. Particle deposition from turbulent flow: Review of published research and its applicability to ventilation ducts in commercial buildings

    Energy Technology Data Exchange (ETDEWEB)

    Sippola, Mark R.; Nazaroff, William W.

    2002-06-01

    This report reviews published experimental and theoretical investigations of particle deposition from turbulent flows and considers the applicability of this body of work to the specific case of particle deposition from flows in the ducts of heating, ventilating and air conditioning (HVAC) systems. Particle deposition can detrimentally affect the performance of HVAC systems and it influences the exposure of building occupants to a variety of air pollutants. The first section of this report describes the types of HVAC systems under consideration and discusses the components, materials and operating parameters commonly found in these systems. The second section reviews published experimental investigations of particle deposition rates from turbulent flows and considers the ramifications of the experimental evidence with respect to HVAC ducts. The third section considers the structure of turbulent airflows in ventilation ducts with a particular emphasis on turbulence investigations that have been used as a basis for particle deposition models. The final section reviews published literature on predicting particle deposition rates from turbulent flows.

  9. Particle deposition modeling in the secondary side of a steam generator bundle model

    Energy Technology Data Exchange (ETDEWEB)

    Mukin, Roman, E-mail: roman.mukin@psi.ch; Dehbi, Abdel, E-mail: abdel.dehbi@psi.ch

    2016-04-01

    A steam generator (SG) tube rupture (SGTR) model is studied in this paper. This model based on a experimental facility called Aerosol Trapping In a Steam Generator (ARTIST), which is a model of a scaled steam generator tube bundle consisting of 270 tubes and a guillotine tube to address aerosol deposition phenomena on two different scales: near the tube break, where the gas velocities and turbulence are very intensive, and far away from the break, where the flow velocities are three orders of magnitude lower. Owing to complexity of the flow, 3D simulations with highly resolved computational mesh near the break were done. First, the flow inside an isolated tube with a guillotine tube break has been studied in the framework of Reynolds Averaged Navier Stokes (RANS) approach. The next part is devoted to the simulation of an inclined gas jet entering the SG tube bundle via the guillotine tube breach with more advanced CFD tools. In particular, Detached Eddy Simulation (DES) and RANS are applied to tackle the wide range of flow scales. Flow field velocity comparison showed that DES results are reproducing wavy structure of the flow field in far field from the break observed in experiment. Particle transport and deposition is modelled by Lagrangian continuous random walk (CRW) model, which has been developed and validated previously. It is found that the DES combined with the CRW to supply fluctuating velocity components predicts deposition rates that are generally within the scatter of the measured data. Monodisperse, spherical SiO{sub 2} particles with AMMD = 1.4 μm were used as aerosol particles in simulations. To be economically feasible, the computations were made with the open source CFD code OpenFOAM. Comparison of the calculated flow with the experimental axial velocity distribution data at different vertical levels has been performed.

  10. Effect of energy deposited by cosmic-ray particles on interferometric gravitational wave detectors

    International Nuclear Information System (INIS)

    Yamamoto, Kazuhiro; Hayakawa, Hideaki; Okada, Atsushi; Uchiyama, Takashi; Miyoki, Shinji; Ohashi, Masatake; Kuroda, Kazuaki; Kanda, Nobuyuki; Tatsumi, Daisuke; Tsunesada, Yoshiki

    2008-01-01

    We investigated the noise of interferometric gravitational wave detectors due to heat energy deposited by cosmic-ray particles. We derived a general formula that describes the response of a mirror against a cosmic-ray passage. We found that there are differences in the comic-ray responses (the dependence of temperature and cosmic-ray track position) in cases of interferometric and resonant gravitational wave detectors. The power spectral density of vibrations caused by low-energy secondary muons is 100 times smaller than the goal sensitivity of future second-generation interferometer projects, such as LCGT and Advanced LIGO. The arrival frequency of high-energy cosmic-ray muons that generate enough large showers inside mirrors of LCGT and Advanced LIGO is one per a millennium. We also discuss the probability of exotic-particle detection with interferometers.

  11. The performance of biological anaerobic filters packed with sludge-fly ash ceramic particles (SFCP) and commercial ceramic particles (CCP) during the restart period: effect of the C/N ratios and filter media.

    Science.gov (United States)

    Yue, Qinyan; Han, Shuxin; Yue, Min; Gao, Baoyu; Li, Qian; Yu, Hui; Zhao, Yaqin; Qi, Yuanfeng

    2009-11-01

    Two lab-scale upflow biological anaerobic filters (BAF) packed with sludge-fly ash ceramic particles (SFCP) and commercial ceramic particles (CCP) were employed to investigate effects of the C/N ratios and filter media on the BAF performance during the restart period. The results indicated that BAF could be restarted normally after one-month cease. The C/N ratio of 4.0 was the thresholds of nitrate removal and nitrite accumulation. TN removal and phosphate uptake reached the maximum value at the same C/N ratio of 5.5. Ammonia formation was also found and excreted a negative influence on TN removal, especially when higher C/N ratios were applied. Nutrients were mainly degraded within the height of 25 cm from the bottom. In addition, SFCP, as novel filter media manufactured by wastes-dewatered sludge and fly ash, represented a better potential in inhibiting nitrite accumulation, TN removal and phosphate uptake due to their special characteristics in comparison with CCP.

  12. Ash cloud aviation advisories

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, T.J.; Ellis, J.S. [Lawrence Livermore National Lab., CA (United States); Schalk, W.W.; Nasstrom, J.S. [EG and G, Inc., Pleasanton, CA (United States)

    1992-06-25

    During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet and every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast Asia, India and beyond. The low-level eruptions (< 7 km) and quasi-steady-state venting produced a plume which generally dispersed to the north and east throughout the support period. Modeling the sequence of eruptions presented a unique challenge. Although the initial approach proved viable, further refinement is necessary and possible. A distinct need exists to quantify eruptions consistently such that ``relative`` ash concentrations relate to specific aviation hazard categories.

  13. Evaluation of five dry particle deposition parameterizations for incorporation into atmospheric transport models

    Science.gov (United States)

    Khan, Tanvir R.; Perlinger, Judith A.

    2017-10-01

    Despite considerable effort to develop mechanistic dry particle deposition parameterizations for atmospheric transport models, current knowledge has been inadequate to propose quantitative measures of the relative performance of available parameterizations. In this study, we evaluated the performance of five dry particle deposition parameterizations developed by Zhang et al. (2001) (Z01), Petroff and Zhang (2010) (PZ10), Kouznetsov and Sofiev (2012) (KS12), Zhang and He (2014) (ZH14), and Zhang and Shao (2014) (ZS14), respectively. The evaluation was performed in three dimensions: model ability to reproduce observed deposition velocities, Vd (accuracy); the influence of imprecision in input parameter values on the modeled Vd (uncertainty); and identification of the most influential parameter(s) (sensitivity). The accuracy of the modeled Vd was evaluated using observations obtained from five land use categories (LUCs): grass, coniferous and deciduous forests, natural water, and ice/snow. To ascertain the uncertainty in modeled Vd, and quantify the influence of imprecision in key model input parameters, a Monte Carlo uncertainty analysis was performed. The Sobol' sensitivity analysis was conducted with the objective to determine the parameter ranking from the most to the least influential. Comparing the normalized mean bias factors (indicators of accuracy), we find that the ZH14 parameterization is the most accurate for all LUCs except for coniferous forest, for which it is second most accurate. From Monte Carlo simulations, the estimated mean normalized uncertainties in the modeled Vd obtained for seven particle sizes (ranging from 0.005 to 2.5 µm) for the five LUCs are 17, 12, 13, 16, and 27 % for the Z01, PZ10, KS12, ZH14, and ZS14 parameterizations, respectively. From the Sobol' sensitivity results, we suggest that the parameter rankings vary by particle size and LUC for a given parameterization. Overall, for dp = 0.001 to 1.0 µm, friction velocity was one of

  14. Evaluation of five dry particle deposition parameterizations for incorporation into atmospheric transport models

    Directory of Open Access Journals (Sweden)

    T. R. Khan

    2017-10-01

    Full Text Available Despite considerable effort to develop mechanistic dry particle deposition parameterizations for atmospheric transport models, current knowledge has been inadequate to propose quantitative measures of the relative performance of available parameterizations. In this study, we evaluated the performance of five dry particle deposition parameterizations developed by Zhang et al. (2001 (Z01, Petroff and Zhang (2010 (PZ10, Kouznetsov and Sofiev (2012 (KS12, Zhang and He (2014 (ZH14, and Zhang and Shao (2014 (ZS14, respectively. The evaluation was performed in three dimensions: model ability to reproduce observed deposition velocities, Vd (accuracy; the influence of imprecision in input parameter values on the modeled Vd (uncertainty; and identification of the most influential parameter(s (sensitivity. The accuracy of the modeled Vd was evaluated using observations obtained from five land use categories (LUCs: grass, coniferous and deciduous forests, natural water, and ice/snow. To ascertain the uncertainty in modeled Vd, and quantify the influence of imprecision in key model input parameters, a Monte Carlo uncertainty analysis was performed. The Sobol' sensitivity analysis was conducted with the objective to determine the parameter ranking from the most to the least influential. Comparing the normalized mean bias factors (indicators of accuracy, we find that the ZH14 parameterization is the most accurate for all LUCs except for coniferous forest, for which it is second most accurate. From Monte Carlo simulations, the estimated mean normalized uncertainties in the modeled Vd obtained for seven particle sizes (ranging from 0.005 to 2.5 µm for the five LUCs are 17, 12, 13, 16, and 27 % for the Z01, PZ10, KS12, ZH14, and ZS14 parameterizations, respectively. From the Sobol' sensitivity results, we suggest that the parameter rankings vary by particle size and LUC for a given parameterization. Overall, for dp  =  0.001 to 1.0

  15. Ash behaviour in fluidized bed gasification and combustion: release of harmful trace elements and the behavior of alkalis; Tuhkan muuntuminen leijukerroskaasutuksessa ja -poltossa: Haitallisten hivenmetallien vapautuminen ja alkalien kaeyttaeytyminen

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E; Valmari, T [VTT Chemical Technology, Espoo (Finland)

    1997-10-01

    During 1996 the behaviour of alkaline metals (K and Na) during circulating fluidized bed combustion of forest residue was studied in a real-scale plant using aerosol measurement instruments (filters, impactor, DMA). Prior to heat exchangers (850 deg C) the ash mass-concentration was 1.0 - 1.3 g/Nm{sup 3} with 1 % of ash forming constituents as vapours. At least 98 % of sulphur, over 90 % of sodium and over 80 % of potassium were found in particulate phase prior to heat exchangers. On the other hand, at least 80 % of the chlorine was in vapour phase. 98 % of the ash was in coarse (> 0.3 {mu}m) particles. Coarse ash particles had an irregular surface structure often consisting of fine primary particles. The remaining 2 % was observed in fine particles of about 0.1 {mu}m. Both rounded and cornered (suggesting crystal structure) fine particles were found. The fine particles were composed of alkali chlorides and sulphates, mainly of KCl. About 80 % of the ash on mass basis was deposited onto heat exchanger surfaces when soot-blowing was not carried out. Practically all of the particles larger than 10 {mu}m were deposited. The deposition was less significant for smaller particles. The fine particle concentration before and after the heat exchangers was the same within the experimental inaccuracy. The deposited fraction of potassium, sodium and sulphur was about the same than that of the total ash: However, the deposition of chlorine was much lower since the chlorine content was low in the coarse particles that were deposited most effectively. (orig.)

  16. Surface chemical characteristics of coal fly ash particles after interaction with seawater under natural deep sea conditions

    International Nuclear Information System (INIS)

    Brami, Y.; Shemesh, A.; Cohen, H.; Herut, B.

    1999-01-01

    The surface chemical characteristics of coal fly ash (CFA) before and after interaction with Mediterranean deep seawater was studied by X-ray photoelectron spectroscopy (XPS). Significantly lower values of Si, Ca, and S and higher values of Mg and Cl were found in the retrieved CFA as compared to fresh CFA. It is suggested that hydrolysis of the oxide matrixes results in an alkaline environment which rapidly leads to several chemical reactions. The two most important are (a) dissolution of the amorphous silicate and the calcium phases and (b) precipitation of Mg(OH) 2 -brucite. A depth profile of the retrieved CFA was measured by both line-shape analysis of the XPS spectra and by consecutive cycle of sputtering. The thickness of the brucite layer is estimated to be 1.3 nm

  17. Deposition of colloidal particles in porous media; Depot de particules minerales de taille colloidale en milieu poreux

    Energy Technology Data Exchange (ETDEWEB)

    Coste, J.P.

    1998-12-09

    The aim of this study was to determine the deposition rates of colloidal particles in porous media in relation with particle stability. It combines experimental results and theoretical analysis and gives an original approach which allows to improve the predictions of particle deposition. The colloidal particles studied are several times smaller than the pore restrictions. Experimental results shows that the porous media surface is heterogeneous, whatever the preparation mean and the history of the porous media. The degree of surface heterogeneity depends both on salinity and porous media cleaning process. Heterogeneity is responsible for initial collection efficiency values higher that the theoretical predictions. When deposition occurs mainly on the less repulsive zones, the velocity dependence of the effective grain collection efficiency is close to the -2/3 value expected for the diffusion limited deposition regime. On the other hand, when these zones have been covered and thus behave as strongly repulsive, we obtain a collection efficiency on the more repulsive zones, with a slope close to -1, which is the value expected for the reaction limited deposition regime. The fraction of surface favorable for deposition can be assessed from attachment efficiency values. The attachment efficiency can be estimated from the measurement of particles stability. (author)

  18. Ash and heavy metals in fluidized bed-combustion; Tuhka ja raskasmetallit puuperaeisen jaetteen kerrosleijupoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Kaessi, T.; Aittoniemi, P. [IVO International, Vantaa (Finland)

    1996-12-01

    Combustion ashes and submicron fly ash particles were characterized in two industrial boilers (bubbling vs. circulating fluidized bed) burning paper mill deinking sludge and bark or wood as support fuel. Bulk samples from fly ash, circulating ash and bottom ash were analyzed. Fine particles in fly ash were monitored and sampled for microscopic studies. The mass size distribution of fly ash was measured and the chemical composition according to particle size was analyzed. The results showed that ash consists of large and friable clusters formed by sintering of small mineral particles originating from paper fillers. Very few ash particles were fused and they were found only among the smallest particles. No agglomerates of fused particles were found. If the residence time in furnace is long enough sintering may proceed further and ash structure grows more dense. No indication of ash vaporization was detected. These results were similar for bubbling and circulating fluidized bed boilers. (author)

  19. Occurrence and dry deposition of organophosphate esters in atmospheric particles over the northern South China Sea.

    Science.gov (United States)

    Lai, Senchao; Xie, Zhiyong; Song, Tianli; Tang, Jianhui; Zhang, Yingyi; Mi, Wenying; Peng, Jinhu; Zhao, Yan; Zou, Shichun; Ebinghaus, Ralf

    2015-05-01

    Nine organophosphate esters (OPEs) in airborne particles were measured during a cruise campaign over the northern South China Sea (SCS) from September to October 2013. The concentration of the total OPEs (∑OPEs) was 47.1-160.9 pg m(-3), which are lower than previous measurements in marine atmosphere environments. Higher OPE concentrations were observed in terrestrially influenced samples, suggesting that OPE concentrations were significantly influenced by air mass transport. Chlorinated OPEs were the dominant OPEs, accounting for 65.8-83.7% of the ∑OPEs. Tris-(2-chloroethyl) phosphate (TCEP) was the predominant OPE compound in the samples (45.0±12.1%), followed by tris-(1-chloro-2-propyl) phosphates (TCPPs) (28.8±8.9%). Dry particle-bound deposition fluxes ranged from 8.2 to 27.8 ng m(-2) d(-1) for the ∑OPEs. Moreover, the dry deposition input of the ∑OPEs was estimated to be 4.98 ton y(-1) in 2013 in a vast area of northern SCS. About half of the input was found to relate to air masses originating from China. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Small Airway Absorption and Microdosimetry of Inhaled Corticosteroid Particles after Deposition.

    Science.gov (United States)

    Longest, P Worth; Hindle, Michael

    2017-10-01

    To predict the cellular-level epithelial absorbed dose from deposited inhaled corticosteroid (ICS) particles in a model of an expanding and contracting small airway segment for different particle forms. A computational fluid dynamics (CFD)-based model of drug dissolution, absorption and clearance occurring in the surface liquid of a representative small airway generation (G13) was developed and used to evaluate epithelial dose for the same deposited drug mass of conventional microparticles, nanoaggregates and a true nanoaerosol. The ICS medications considered were budesonide (BD) and fluticasone propionate (FP). Within G13, total epithelial absorption efficiency (AE) and dose uniformity (microdosimetry) were evaluated. Conventional microparticles resulted in very poor AE of FP (0.37%) and highly nonuniform epithelial absorption, such that <5% of cells received drug. Nanoaggregates improved AE of FP by a factor of 57-fold and improved dose delivery to reach approximately 40% of epithelial cells. True nanoaerosol resulted in near 100% AE for both drugs and more uniform drug delivery to all cells. Current ICS therapies are absorbed by respiratory epithelial cells in a highly nonuniform manner that may partially explain poor clinical performance in the small airways. Both nanoaggregates and nanoaerosols can significantly improve ICS absorption efficiency and uniformity.

  1. Turbulence in the trachea and its effect on micro-particle deposition

    Science.gov (United States)

    Geisler, Taylor; Shaqfeh, Eric; Iaccarino, Gianluca

    2017-11-01

    The health effects of inhaled aerosols are often predicted by extrapolating experimental data taken using nonhuman primate animal studies to humans. While the existence of a laminar-to-turbulent flow transition in the human larynx is widely reported in the literature, it was previously unknown, to our knowledge, whether a similar flow behavior exists in the airways of rhesus monkeys. By using Large Eddy Simulation (LES) in the CT-based airway models of rhesus monkeys we demonstrate the existence of such a flow transition at elevated inspiratory flow rates. The geometries comprise the nasal cavity, larynx, and trachea. We observe turbulence intensity values that peak after the larynx and decay throughout the trachea similar to that of humans. Deposition of inhaled micro-particles is also computed and validated using experiments in 3D-printed model airways with excellent agreement. Deposition in the turbulent regions of the airway (larynx and trachea) is shown to be substantial at elevated flow rates and to depend on the flow unsteadiness. These results provide insight into the fate of inhaled particles in rhesus monkey animal experiments and their connection to human inhalation.

  2. Cu and Cu2O films with semi-spherical particles grown by electrochemical deposition

    International Nuclear Information System (INIS)

    Zheng, Jin You; Jadhav, Abhijit P.; Song, Guang; Kim, Chang Woo; Kang, Young Soo

    2012-01-01

    Cu and Cu 2 O films can be prepared on indium-doped tin oxide glass substrates by simple electrodeposition in a solution containing 0.1 M Cu(NO 3 ) 2 and 3 M lactic acid at different pH values. At low pH (pH = 1.2), the uniform Cu films were obtained; when pH ≥ 7, the pure Cu 2 O films can be deposited. Especially, at pH = 11, the deposited Cu 2 O films exhibited cubic surface morphology exposing mainly {100} plane; in contrast, the films consisting of semi-spherical particles were obtained when the solution was being stirred for 2 weeks prior to use. The possible growth process and mechanism were comparatively discussed. - Highlights: ► Cu and Cu 2 O films were prepared by facile electrodeposition. ► Electrodeposition was preformed in electrolyte at different pH values. ► Dendritic Cu films were obtained at 1.2 pH with relatively high deposition potential. ► Semi-spherical Cu 2 O films were obtained with solution at 11 pH and stirred for 2 weeks. ► The possible growth mechanism of semi-spherical Cu 2 O films was discussed.

  3. Review on urban vegetation and particle air pollution - Deposition and dispersion

    Science.gov (United States)

    Janhäll, Sara

    2015-03-01

    Urban vegetation affects air quality through influencing pollutant deposition and dispersion. Both processes are described by many existing models and experiments, on-site and in wind tunnels, focussing e.g. on urban street canyons and crossings or vegetation barriers adjacent to traffic sources. There is an urgent need for well-structured experimental data, including detailed empirical descriptions of parameters that are not the explicit focus of the study. This review revealed that design and choice of urban vegetation is crucial when using vegetation as an ecosystem service for air quality improvements. The reduced mixing in trafficked street canyons on adding large trees increases local air pollution levels, while low vegetation close to sources can improve air quality by increasing deposition. Filtration vegetation barriers have to be dense enough to offer large deposition surface area and porous enough to allow penetration, instead of deflection of the air stream above the barrier. The choice between tall or short and dense or sparse vegetation determines the effect on air pollution from different sources and different particle sizes.

  4. The influence of inhalation technique on Technegas particle deposition and image appearance in normal volunteers

    International Nuclear Information System (INIS)

    Lloyd, J.J.; James, J.M.; Shields, R.A.; Testa, H.J.

    1994-01-01

    The aim of this work was to investigate the influence of inhalation technique on Technegas image quality and on fractional particle deposition. This was investigated in six normal volunteers using three different types of breathing pattern. Fractional deposition was determined by analysis of dynamic gamma camera images acquired during Technegas administration. Static lung images were subsequently acquired and assessed independently by three experienced observers. High-quality images were obtained in all cases although slight differences were noted. The images produced using a slow deep inspiration with a breath hold (i.e. the standard method) were of more uniform texture and also had the least gradient in activity from apex to base. The converse was true for a rapid inhalation technique. The average fractional deposition per breath was 55%, but this varied between individuals and with breathing pattern, being most influenced by the total duration of a breath. We conclude that for patient studies the standard inhalation technique is best, although variation to suit individual patients would be acceptable. (orig./MG)

  5. Particle and power deposition on divertor targets in EAST H-mode plasmas

    International Nuclear Information System (INIS)

    Wang, L.; Xu, G.S.; Guo, H.Y.; Chen, R.; Ding, S.; Gan, K.F.; Gao, X.; Gong, X.Z.; Jiang, M.; Liu, P.; Liu, S.C.; Luo, G.N.; Ming, T.F.; Wan, B.N.; Wang, D.S.; Wang, F.M.; Wang, H.Q.; Wu, Z.W.; Yan, N.; Zhang, L.

    2012-01-01

    The effects of edge-localized modes (ELMs) on divertor particle and heat fluxes were investigated for the first time in the Experimental Advanced Superconducting Tokamak (EAST). The experiments were carried out with both double null and lower single null divertor configurations, and comparisons were made between the H-mode plasmas with lower hybrid current drive (LHCD) and those with combined ion cyclotron resonance heating (ICRH). The particle and heat flux profiles between and during ELMs were obtained from Langmuir triple-probe arrays embedded in the divertor target plates. And isolated ELMs were chosen for analysis in order to reduce the uncertainty resulting from the influence of fast electrons on Langmuir triple-probe evaluation during ELMs. The power deposition obtained from Langmuir triple probes was consistent with that from the divertor infra-red camera during an ELM-free period. It was demonstrated that ELM-induced radial transport predominantly originated from the low-field side region, in good agreement with the ballooning-like transport model and experimental results of other tokamaks. ELMs significantly enhanced the divertor particle and heat fluxes, without significantly broadening the SOL width and plasma-wetted area on the divertor target in both LHCD and LHCD + ICRH H-modes, thus posing a great challenge for the next-step high-power, long-pulse operation in EAST. Increasing the divertor-wetted area was also observed to reduce the peak heat flux and particle recycling at the divertor target, hence facilitating long-pulse H-mode operation. The particle and heat flux profiles during ELMs appeared to exhibit multiple peak structures, and were analysed in terms of the behaviour of ELM filaments and the flux tubes induced by modified magnetic topology during ELMs. (paper)

  6. Treated bottom ash medium and method of arsenic removal from drinking water

    Science.gov (United States)

    Gadgil, Ashok

    2009-06-09

    A method for low-cost arsenic removal from drinking water using chemically prepared bottom ash pre-treated with ferrous sulfate and then sodium hydroxide. Deposits on the surface of particles of bottom ash form of activated iron adsorbent with a high affinity for arsenic. In laboratory tests, a miniscule 5 grams of pre-treated bottom ash was sufficient to remove the arsenic from 2 liters of 2400 ppb (parts per billion) arsenic-laden water to a level below 50 ppb (the present United States Environmental Protection Agency limit). By increasing the amount of pre-treated bottom ash, even lower levels of post-treatment arsenic are expected. It is further expected that this invention supplies a very low-cost solution to arsenic poisoning for large population segments.

  7. High-pressure turbine deposition in land-based gas turbines from various synfuels

    Energy Technology Data Exchange (ETDEWEB)

    Bons, J.P.; Crosby, J.; Wammack, J.E.; Bentley, B.I.; Fletcher, T.H. [Brigham Young University, Provo, UT (United States). Dept. of Mechanical Engineering

    2007-01-15

    Ash deposits from four candidate power turbine synfuels were studied in an accelerated deposition test facility. The facility matches the gas temperature and velocity of modern first-stage high-pressure turbine vanes. A natural gas combustor was seeded with finely ground fuel ash particulate from four different fuels: straw, sawdust, coal, and petroleum coke. The entrained ash particles were accelerated to a combustor exit flow Mach number of 0.31 before impinging on a thermal barrier coating (TBC) target coupon at 1150{sup o}C. Postexposure analyses included surface topography, scanning electron microscopy and x-ray spectroscopy. Due to significant differences in the chemical composition of the various fuel ash samples, deposit thickness and structure vary considerably for fuel. Biomass products (e.g., sawdust and straw) are significantly less prone to deposition than coal and petcoke for the same particle loading conditions. In a test simulating one turbine operating year at a moderate particulate loading of 0.02 parts per million by weight, deposit thickness from coal and petcoke ash exceeded 1 and 2 mm, respectively. These large deposits from coal and petcoke were found to detach readily from the turbine material with thermal cycling and handling. The smaller biomass deposit samples showed greater tenacity, in adhering to the TBC surface. In all cases, corrosive elements (e.g., Na, K, V, Cl, S) were found to penetrate the TBC layer during the accelerated deposition test. Implications for the power generation goal of fuel flexibility are discussed.

  8. Concentration, size distribution and dry deposition of amines in atmospheric particles of urban Guangzhou, China

    Science.gov (United States)

    Liu, Fengxian; Bi, Xinhui; Zhang, Guohua; Peng, Long; Lian, Xiufeng; Lu, Huiying; Fu, Yuzhen; Wang, Xinming; Peng, Ping'an; Sheng, Guoying

    2017-12-01

    Size-segregated PM10 samples were collected in Guangzhou, China during autumn of 2014. Nine amines, including seven aliphatic amines and two heterocyclic amines, were detected using a gas chromatography-mass spectrometer after derivatization by benzenesulfonyl chloride. The total concentration of the nine amines (Ʃamines) was 79.6-140.9 ng m-3 in PM10. The most abundant species was methylamine (MA), which had a concentration of 29.2-70.1 ng m-3. MA, dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA) were the predominant amines in the samples and accounted for approximately 80% of Ʃamines in each size segment. Two heterocyclic amines, pyrrolidine (PYR) and morpholine (MOR), were detected in all samples and had average concentrations of 1.14 ± 0.37 and 1.89 ± 0.64 ng m-3, respectively, in particles with aerodynamic diameters ammonium ranged from 0.0068 to 0.0107 in particles with diameters <1.5 μm, and the maximum ratio occurred in the smallest particles (diameter< 0.49 μm). The average dry deposition flux and velocity of Ʃamines in PM10 were 7.9 ± 1.6 μg m-2 d-1 and 0.084 ± 0.0021 cm s-1, respectively. The results of this study provide essential information on the contribution of amines to secondary organic aerosols and dry removal mechanisms in urban areas.

  9. A robust upscaling of the effective particle deposition rate in porous media

    Science.gov (United States)

    Boccardo, Gianluca; Crevacore, Eleonora; Sethi, Rajandrea; Icardi, Matteo

    2018-05-01

    In the upscaling from pore to continuum (Darcy) scale, reaction and deposition phenomena at the solid-liquid interface of a porous medium have to be represented by macroscopic reaction source terms. The effective rates can be computed, in the case of periodic media, from three-dimensional microscopic simulations of the periodic cell. Several computational and semi-analytical models have been studied in the field of colloid filtration to describe this problem. They typically rely on effective deposition rates defined by complex fitting procedures, neglecting the advection-diffusion interplay, the pore-scale flow complexity, and assuming slow reactions (or large Péclet numbers). Therefore, when these rates are inserted into general macroscopic transport equations, they can lead to several conceptual inconsistencies and significant errors. To study more accurately the dependence of deposition on the flow parameters, in this work we advocate a clear distinction between the surface processes (that altogether defines the so-called attachment efficiency), and the pore-scale processes. With this approach, valid when colloidal particles are small enough, we study Brownian and gravity-driven deposition on a face-centred cubic (FCC) arrangement of spherical grains, and define a robust upscaling based on a linear effective reaction rate. The case of partial deposition, defined by an attachment probability, is studied and the limit of perfect sink is retrieved as a particular case. We introduce a novel upscaling approach and a particularly convenient computational setup that allows the direct computation of the asymptotic stationary value of effective rates. This allows to drastically reduce the computational domain down to the scale of the single repeating periodic unit. The savings are ever more noticeable in the case of higher Péclet numbers, when larger physical times are needed to reach the asymptotic regime and thus, equivalently, much larger computational domain and

  10. Engineering Behavior and Characteristics of Wood Ash and Sugarcane Bagasse Ash

    Directory of Open Access Journals (Sweden)

    Francisco Grau

    2015-10-01

    Full Text Available Biomasses are organic materials that are derived from any living or recently-living structure. Plenty of biomasses are produced nationwide. Biomasses are mostly combusted and usually discarded or disposed of without treatment as biomass ashes, which include wood and sugarcane bagasse ashes. Thus, recycling or treatment of biomass ashes leads to utilizing the natural materials as an economical and environmental alternative. This study is intended to provide an environmental solution for uncontrolled disposal of biomass ashes by way of recycling the biomass ash and replacing the soils in geotechnical engineering projects. Therefore, in this study, characteristic tests of wood and sugarcane bagasse ashes that are considered the most common biomass ashes are conducted. The test of chemical compositions of biomass ashes is conducted using energy dispersive X-ray spectroscopy (EDS, and Scanning Electron Microscope (SEM, and heavy metal analysis is also conducted. Engineering behaviors including hydraulic conductivity, constrained modulus and shear modulus are examined. Also, coal fly ash Class C is used in this study for comparison with biomass ashes, and Ottawa 20/30 sands containing biomass ashes are examined to identify the soil replacement effect of biomass ashes. The results show that the particle sizes of biomass ashes are halfway between coal fly ash Class C and Ottawa 20/30 sand, and biomass ashes consist of a heterogeneous mixture of different particle sizes and shapes. Also, all heavy metal concentrations were found to be below the US Environmental Protection Agency (EPA maximum limit. Hydraulic conductivity values of Ottawa 20/30 sand decrease significantly when replacing them with only 1%–2% of biomass ashes. While both the constrained modulus and shear modulus of biomass ashes are lower than Ottawa 20/30 sand, those of mixtures containing up to 10% biomass ashes are little affected by replacing the soils with biomass ashes.

  11. Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation

    Directory of Open Access Journals (Sweden)

    J. D. Whitehead

    2010-01-01

    Full Text Available Here we present the first observations of simultaneous ozone deposition fluxes and ultrafine particle emission fluxes over an extensive infra-littoral zone. Fluxes were measured by the eddy covariance technique at the Station Biologique de Roscoff, on the coast of Brittany, north-west France. This site overlooks a very wide (3 km littoral zone controlled by very deep tides (9.6 m exposing extensive macroalgae beds available for significant iodine mediated photochemical production of ultrafine particles. The aspect at the Station Biologique de Roscoff provides an extensive and relatively flat, uniform fetch within which micrometeorological techniques may be utilized to study links between ozone deposition to macroalgae (and sea water and ultrafine particle production.

    Ozone deposition to seawater at high tide was significantly slower (vd[O3]=0.302±0.095 mm s−1 than low tidal deposition. A statistically significant difference in the deposition velocities to macroalgae at low tide was observed between night time (vd[O3]=1.00±0.10 mm s−1 and daytime (vd[O3]=2.05±0.16 mm s−1 when ultrafine particle formation results in apparent particle emission. Very high emission fluxes of ultrafine particles were observed during daytime periods at low tides ranging from 50 000 particles cm−2 s−1 to greater than 200 000 particles cm−2 s−1 during some of the lowest tides. These emission fluxes exhibited a significant relationship with particle number concentrations comparable with previous observations at another location. Apparent particle growth rates were estimated to be in the range 17–150 nm h−1 for particles in the size range 3–10 nm. Under certain conditions, particle growth may be inferred to continue to greater than 120 nm over tens

  12. Direct deposition of gas phase generated aerosol gold nanoparticles into biological fluids--corona formation and particle size shifts.

    Directory of Open Access Journals (Sweden)

    Christian R Svensson

    Full Text Available An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity to a large extent may determine the nanoparticle effects and possible translocation to other organs.

  13. Direct Deposition of Gas Phase Generated Aerosol Gold Nanoparticles into Biological Fluids - Corona Formation and Particle Size Shifts

    Science.gov (United States)

    Svensson, Christian R.; Messing, Maria E.; Lundqvist, Martin; Schollin, Alexander; Deppert, Knut; Pagels, Joakim H.; Rissler, Jenny; Cedervall, Tommy

    2013-01-01

    An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP) are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity) to a large extent may determine the nanoparticle effects and possible translocation to other organs. PMID:24086363

  14. Identifying glass compositions in fly ash

    Directory of Open Access Journals (Sweden)

    Katherine eAughenbaugh

    2016-01-01

    Full Text Available In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS, calcium aluminosilicate glasses (CAS, a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  15. Transport and deposition of particles and radionuclides at the Puy de Dome, France

    International Nuclear Information System (INIS)

    Bourcier, L.

    2009-01-01

    Aerosol particles play a key role both on air quality and on the radiative balance of the Earth. Their sources, as well as their deposition are key stages in their life cycle. This work is a contribution in a better knowledge of the chemical composition of particles, cloud droplets and rain droplets. The specificity of our study is to couple, on three sampling sites (Puy de Dome (1465 m a.s.l.), Opme (660 m a.s.l.) and Cezeaux (400 m a.s.l.)), observations on the chemical composition and the radionuclides activity in cloud/rain/aerosol phases. We observed, in aerosol phase, ionic and carbonaceous concentrations and radionuclides activity higher in summer than in winter at the Puy de Dome, inverse of the seasonal variation observed at the Cezeaux for chemical compounds. From these observations, we offer a representative composition de each mass air type. This work is supplemented by a study of cloud and rain liquid, which allow us to study the scavenging of the pollutants by the rain. The chemical composition of the rain reveals a similar behaviour to that of the particles at the Puy de Dome, indicating that the role of activation and scavenging of particles is preponderant in the composition of the rain. This is confirmed by a study of the environmental and structural factors of the rain which do not seem to influence the washout ratio in a significant manner. Our work highlights the role of long range transport of pollutants in the composition of atmospheric liquid phase. (author)

  16. Combined exposure of diesel exhaust particles and respirable Soufrière Hills volcanic ash causes a (pro-)inflammatory response in an in vitro multicellular epithelial tissue barrier model

    Science.gov (United States)

    Tomašek, Ines; Horwell, Claire J.; Damby, David; Barošová, Hana; Geers, Christoph; Petri-Fink, Alke; Rothen-Rutishauser, Barbara; Clift, Martin J. D.

    2016-01-01

    BackgroundThere are justifiable health concerns regarding the potential adverse effects associated with human exposure to volcanic ash (VA) particles, especially when considering communities living in urban areas already exposed to heightened air pollution. The aim of this study was, therefore, to gain an imperative, first understanding of the biological impacts of respirable VA when exposed concomitantly with diesel particles.MethodsA sophisticated in vitro 3D triple cell co-culture model of the human alveolar epithelial tissue barrier was exposed to either a single or repeated dose of dry respirable VA (deposited dose of 0.26 ± 0.09 or 0.89 ± 0.29 μg/cm2, respectively) from Soufrière Hills volcano, Montserrat for a period of 24 h at the air-liquid interface (ALI). Subsequently, co-cultures were exposed to co-exposures of single or repeated VA and diesel exhaust particles (DEP; NIST SRM 2975; 0.02 mg/mL), a model urban pollutant, at the pseudo-ALI. The biological impact of each individual particle type was also analysed under these precise scenarios. The cytotoxic (LDH release), oxidative stress (depletion of intracellular GSH) and (pro-)inflammatory (TNF-α, IL-8 and IL-1β) responses were assessed after the particulate exposures. The impact of VA exposure upon cell morphology, as well as its interaction with the multicellular model, was visualised via confocal laser scanning microscopy (LSM) and scanning electron microscopy (SEM), respectively.ResultsThe combination of respirable VA and DEP, in all scenarios, incited an heightened release of TNF-α and IL-8 as well as significant increases in IL-1β, when applied at sub-lethal doses to the co-culture compared to VA exposure alone. Notably, the augmented (pro-)inflammatory responses observed were not mediated by oxidative stress. LSM supported the quantitative assessment of cytotoxicity, with no changes in cell morphology within the barrier model evident. A direct interaction of the VA with all

  17. Electrokinetic deposition of waterborne, particlate FeO(OH) and MnO2 on stainless steel surfaces

    International Nuclear Information System (INIS)

    Hermansson, H.-P.

    1977-01-01

    The study forms part of a programme of research into corrosion product behaviour in progress at Studsvik Energiteknik AB. Attention is in this instance focused on the incluence of electrokinetic factors upon the deposition of particulate corrosion products. The work has involved the development of experimental apparatus and techniques and investigation of the deposition characteristics of FeO(OH) and MnO 2 at temperatures below 100 deg C. The experimental results indicate that the deposition rate of the compounds under review depends mainly upon the zeta potential (zeta) of particles and of the test section wall. The deposition rate attains a maximum when the zeta potential is at a minimum or zero. Deposition occurs when |zeta|< approximately 40 m. Outside this interval deposition is not observed. Furthermore, the deposition rate maximum depends upon the rate of change of pH both as regards its magnitude and its position on the pH scale. This dependence can be accounted for in terms of a general drain of material from the loop as deposition proceeds and a difference in zeta potential between particles and the wall surface of the test section. (author)

  18. Hot-Gas Filter Ash Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, M.L.; Hurley, J.P.; Dockter, B.A.; O`Keefe, C.A.

    1997-07-01

    Large-scale hot-gas filter testing over the past 10 years has revealed numerous cases of cake buildup on filter elements that has been difficult, if not impossible, to remove. At times, the cake can blind or bridge between candle filters, leading to filter failure. Physical factors, including particle-size distribution, particle shape, the aerodynamics of deposition, and system temperature, contribute to the difficulty in removing the cake, but chemical factors such as surface composition and gas-solid reactions also play roles in helping to bond the ash to the filters or to itself. This project is designed to perform the research necessary to determine the fuel-, sorbent-, and operations-related conditions that lead to blinding or bridging of hot-gas particle filters. The objectives of the project are threefold: (1) Determine the mechanisms by which a difficult-to-clean ash is formed and how it bridges hot-gas filters (2) Develop a method to determine the rate of bridging based on analyses of the feed coal and sorbent, filter properties, and system operating conditions and (3) Suggest and test ways to prevent filter bridging.

  19. Model for deposition and long-term disposition of 134Cs-labeled fused aluminosilicate particles inhaled by guinea pigs

    International Nuclear Information System (INIS)

    Snipes, M.B.; McClellan, R.O.

    1986-01-01

    When considering which laboratory animal species to use in inhalation studies, it is important to evaluate the similarities and differences in deposition and fate of the inhaled materials in various laboratory animals compared with humans. Beagle dogs have deposition and clearance patterns of inhaled particles similar to humans. However, some studies require smaller laboratory animals to be cost effective or to allow an adequate number of animals to address the scientific questions. This study evaluated the deposition and clearance of a relatively insoluble aerosol inhaled by guinea pigs. The test aerosol was monodisperse 134 Cs-labeled fused aluminosilicate particles inhaled during 75 minute inhalation exposure. The guinea pigs had deposition similar to rats but respiratory tract retention and clearance patterns were similar to dogs and humans. 5 references, 2 figures, 1 table

  20. Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

    OpenAIRE

    Antoni; Sulistio Aldi Vincent; Wahjudi Samuel; Hardjito Djwantoro; Hardjito Djwantoro

    2017-01-01

    Bottom ash is a coal plant by-product that is abundant and underutilized. There is the potential use of bottom ash as a fine aggregate replacement in concrete mixtures; however, the problems of water absorption and uniformity of quality of the material need to be overcome first. In this study, bottom ash was treated by sieve separation and pounding to smaller particle size for use as a sand substitute. The physical and chemical characteristics of bottom ash were tested after treatment includi...

  1. The erosion performance of particle reinforced metal matrix composite coatings produced by co-deposition cold gas dynamic spraying

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This work reports on the erosion performance of three particle reinforced metal matrix composite coatings, co-deposited with an aluminium binder via cold-gas dynamic spraying. The deposition of ceramic particles is difficult to achieve with typical cold spray techniques due to the absence of particle deformation. This issue has been overcome in the present study by simultaneously spraying the reinforcing particles with a ductile metallic binder which has led to an increased level of ceramic/cermet particles deposited on the substrate with thick (>400 μm) coatings produced. The aim of this investigation was to evaluate the erosion performance of the co-deposited coatings within a slurry environment. The study also incorporated standard metallographic characterisation techniques to evaluate the distribution of reinforcing particles within the aluminium matrix. All coatings exhibited poorer erosion performance than the uncoated material, both in terms of volume loss and mass loss. The Al2O3 reinforced coating sustained the greatest amount of damage following exposure to the slurry and recorded the greatest volume loss (approx. 2.8 mm3) out of all of the examined coatings. Despite the poor erosion performance, the WC-CoCr reinforced coating demonstrated a considerable hardness increase over the as-received AA5083 (approx. 400%) and also exhibited the smallest free space length between adjacent particles. The findings of this study reveal that the removal of the AA5083 matrix by the impinging silicon carbide particles acts as the primary wear mechanism leading to the degradation of the coating. Analysis of the wear scar has demonstrated that the damage to the soft matrix alloy takes the form of ploughing and scoring which subsequently exposes carbide/oxide particles to the impinging slurry.

  2. Local energy deposited for alpha particles emitted from inhaled radon daughters

    International Nuclear Information System (INIS)

    Al-affan, I.A.M.; Haque, A.K.M.M.

    1989-01-01

    An analytical method has been developed to calculate the local energy deposited by alpha particles emitted from radon daughters deposited on the mucus surface in the lung airways. For the particular case of 218 Po (Ra A) and 214 Bi (Ra C'), microdose spectra have been evaluated in test spheres of 1 μm diameter which were taken to lie within airways of diameters 18 000, 3500 and 600 μm. In each case, the contributions of the near and far wall were computed separately. The average microdosimetric parameters y-bar F and y-bar D have also been calculated. For the two smaller airways, y-bar F and y-bar D values were found to be about 110 and 135 keV μm -1 for 218 Po and about 87 and 107 keV μm -1 for 214 Bi respectively. The corresponding values were about 10% higher for the largest airway. (author)

  3. Ash and heavy metals in fluidized-bed combustion of wood wastes; Tuhka ja raskasmetallit puuperaeisen jaetteen kerrosleijupoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Kaessi, T; Aittoniemi, P [IVO Power Engineering, Vantaa (Finland); Kauppinen, E; Latva-Somppi, J; Kurkela, J [VTT Chemical Technology, Espoo (Finland); Partanen, J [IVO Technology Centre, Vantaa (Finland)

    1997-10-01

    Ash formation and deposition mechanisms during co-combustion of pulp mill sludge and bark in industrial bubbling fluidized bed (BFB) combustor have been studied. Similar fuels were used in a bench-scale BFB for co-combustion of sludge and bark pellets and comparative studies with separate combustion of these fuels. Results indicated that in industrial scale unit significant fraction of ash had vaporization. About 14 mass-% of the total fly ash was found in the particle size below 0.2 {mu}m. The vaporized species consisted of potassium (K), sulfur (S), chlorine (Cl) and also of minor quantities of sodium (Na). In the benchscale similar vaporization fractions during co-combustion were measured, about 11 mass-%. During the combustion of bark this ratio, about 20 mass-%, was higher than during sludge combustion. The vaporized ash fraction was in the case of dried sludge combustion about 7 mass-%, but with wet sludge the vaporization rate was remarkably lower, about 1-2 mass-%. An increase in the bed temperature increased also ash vaporization. Test run period without combustion at elevated temperatures produced very low quantities of vaporized ash. The vaporized species in bench-scale test during bark pellet combustion were K, S and Cl, for sludge combustion also Na was clearly detected. No condensation of the vaporized species in bed area or furnace walls was observed. Bed defluidization was studied in the bench-scale unit. During bark pellet combustion the bed-agglomeration proceeded via small ash particle, below 2 {mu}m, coating on sand particle surface and consequent bonding between the ash layers. In the case of sludge combustion the accumulation of large ash particles and sintering of these porous agglomerates was observed to cause bed coarsening and defluidization. (orig.)

  4. The importance of ash for the favourable properties of sewage sludge in co-firing; Askans betydelse foer roetslams goda samfoerbraenningsegenskaper

    Energy Technology Data Exchange (ETDEWEB)

    Davidsson, K.; Jones, F.; Niklasson, F.; Ryde, D. [SP Sveriges Tekniska Forskningsinstitut, Boraas, (Sweden); Gustafsson, G. [Boraas Energi och Miljoe, Boraas (Sweden); Herstad Svaerd, S. [WSP Kraft and Vaerme, Goeteborg (Sweden)

    2012-11-01

    Sewage sludge has been shown to have positive properties during cofiring with difficult fuels. The sludge mitigates deposition and corrosion which occur because of the fuels content of chlorine and alkali. The reason for the positive properties of sludge are its content of sulphur, phosphorus and aluminium silicates. Its high content of ash has also been discussed because the fly ash would constitute a large surface for alkali chlorides to condensate on and thereby avoid condensation on e.g. superheater surfaces. The ash could also blast the surface and thereby keeping them clean. The present project aims at testing the hypothesis that the ash in the sludge mitigates the deposition. Tests have been performed with synthetically produced waste pellets of which some were doped with inert particles in form of aluminium oxide. The tests were done in a lab-scale bubbling fluidised bed. Deposit probes collected deposits during the combustion of doped and un-doped waste pellets, and the deposits were chemically analysed. The result shows that the inert particles do not have any effect on the amount of hard attached deposits. The particles ended up on the lee side of the probe where they deposited because of gravitation, but they could be easily removed. The remaining deposit was analysed and the effect of inert particles was a small decrease of the content of chlorine. Tests were also performed with pellets doped with sludge. In this case the amount of deposit and its content of chlorine decreased significantly. Different sewage sludges have different properties. The present results show that sludge for cofiring should not be chosen for its amount of ash but rather for its content of sulphur, phosphorous and aluminium.

  5. The importance of ash for the favourable properties of sewage sludge in co-firing; Askans betydelse foer roetslams goda samfoerbraenningsegenskaper

    Energy Technology Data Exchange (ETDEWEB)

    Davidsson, K.; Jones, F.; Niklasson, F.; Ryde, D. [SP Sveriges Tekniska Forskningsinstitut, Boraas (Sweden); Gustafsson, G. [Boraas Energi och Miljoe, Boraas (Sweden); Herstad Svaerd, S. [WSP Kraft and Vaerme, Stockholm (Sweden)

    2012-07-01

    Sewage sludge has been shown to have positive properties during cofiring with difficult fuels. The sludge mitigates deposition and corrosion which occur because of the fuels content of chlorine and alkali. The reason for the positive properties of sludge are its content of sulphur, phosphorus and aluminium silicates. Its high content of ash has also been discussed because the fly ash would constitute a large surface for alkali chlorides to condensate on and thereby avoid condensation on e.g. superheater surfaces. The ash could also blast the surface and thereby keeping them clean. The present project aims at testing the hypothesis that the ash in the sludge mitigates the deposition. Tests have been performed with synthetically produced waste pellets of which some were doped with inert particles in form of aluminium oxide. The tests were done in a lab-scale bubbling fluidised bed. Deposit probes collected deposits during the combustion of doped and un-doped waste pellets, and the deposits were chemically analysed. The result shows that the inert particles do not have any effect on the amount of hard attached deposits. The particles ended up on the lee side of the probe where they deposited because of gravitation, but they could be easily removed. The remaining deposit was analysed and the effect of inert particles was a small decrease of the content of chlorine. Tests were also performed with pellets doped with sludge. In this case the amount of deposit and its content of chlorine decreased significantly. Different sewage sludges have different properties. The present results show that sludge for cofiring should not be chosen for its amount of ash but rather for its content of sulphur, phosphorous and aluminium.

  6. Particle deposition in human and canine tracheobronchial casts: Annual progress report

    International Nuclear Information System (INIS)

    Cohen, B.S.

    1987-01-01

    This work measures deposition patterns and efficiencies of aerosols within realistic, physical models of the tracheobronchial airways of humans and experimental animals over a range of particle sizes from 0.01 to 1.0 μm, for a variety of respiratory modes and rates. Full morphometric and flow distribution measurements were completed on casts of human and canine tracheobronchial airways, which extend from just below the larynx to airways 1 mm in diameter. They show basic similarities in the distribution of airflow, but also species differences which must be considered. The distribution of airflow was measured for minute volumes equivalent to 6, 11, 17 and 22 L min -1 for the human and 3, 6, 8 and 11 L min -1 for the canine for both constant and pulsatile inspiratory flow. Inertance was found to carry more of the flow to airways of the lower lobes at higher flow rates. Basic differences in airway branching pattern result in a more distinct change in airflow distribution as flow rate changes for the canine cast as compared with the human cast. These differences will contribute to differing patterns of mass transfer of inhaled particles in central airways of the two species. 8 refs., 2 figs., 5 tabs

  7. TiB2/Al2O3 ceramic particle reinforced aluminum fabricated by spray deposition

    International Nuclear Information System (INIS)

    Chen Xing; Yang Chengxiao; Guan Leding; Yan Biao

    2008-01-01

    Aluminum matrix ceramic particle reinforced composites (AMCs) is a kind of composite with great importance. Aluminum matrix composite reinforced with TiB 2 /Al 2 O 3 ceramic particles was successfully in situ synthesized in Al-TiO 2 -B 2 O 3 system in this paper, using spray deposition with hot-press treatment technique. Five groups of composites with different reinforcement volume contents were prepared and the comparisons of porosity, ultimate tensile strength (UTS), elongation and Brinell hardness (BH) between the composites with and without hot-press treating were carried out. The composite with 21.0% reinforcement volume content was analyzed by X-ray diffraction (XRD), Environmental Scanning Electron Microscope (ESEM), Transmission Electron Microscope (TEM) and Energy Disperse Spectroscopy (EDS). The results revealed the formation and uniform distribution of fine reinforcements in the matrix after hot-press treating, while a new intermetallic phase Al 3 Ti was found besides TiB 2 /Al 2 O 3 ceramic phase

  8. The Effect of Volcanic Ash Composition on Ice Nucleation Affinity

    Science.gov (United States)

    Genareau, K. D.; Cloer, S.; Primm, K.; Woods, T.; Tolbert, M. A.

    2017-12-01

    Understanding the role that volcanic ash plays in ice nucleation is important for knowledge of lightning generation in both volcanic plumes and in clouds developing downwind from active volcanoes. Volcanic ash has long been suggested to influence heterogeneous ice nucleation following explosive eruptions, but determining precisely how composition and mineralogy affects ice nucleation affinity (INA) is poorly constrained. For the study presented here, volcanic ash samples with different compositions and mineral/glass contents were tested in both the deposition and immersion modes, following the methods presented in Schill et al. (2015). Bulk composition was determined with X-ray fluorescence (XRF), grain size distribution was determined with laser diffraction particle size analysis (LDPSA), and mineralogy was determined with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results of the deposition-mode experiments reveal that there is no relationship between ice saturation ratios (Sice) and either mineralogy or bulk ash composition, as all samples have similar Sice ratios. In the immersion-mode experiments, frozen fractions were determined from -20 °C to -50 °C using three different amounts of ash (0.5, 1.0, and 2.0 wt% of slurry). Results from the immersion freezing reveal that the rhyolitic samples (73 wt% SiO2) nucleate ice at higher temperatures compared to the basaltic samples (49 wt% SiO2). There is no observed correlation between frozen fractions and mineral content of ash samples, but the two most efficient ice nuclei are rhyolites that contain the greatest proportion of amorphous glass (> 90 %), and are enriched in K2O relative to transition metals (MnO and TiO2), the latter of which show a negative correlation with frozen fraction. Higher ash abundance in water droplets increases the frozen fraction at all temperatures, indicating that ash amount plays the biggest role in ice nucleation. If volcanic ash can reach sufficient abundance (

  9. Monte Carlo study of radial energy deposition from primary and secondary particles for narrow and large proton beamlet source models

    International Nuclear Information System (INIS)

    Peeler, Christopher R; Titt, Uwe

    2012-01-01

    In spot-scanning intensity-modulated proton therapy, numerous unmodulated proton beam spots are delivered over a target volume to produce a prescribed dose distribution. To accurately model field size-dependent output factors for beam spots, the energy deposition at positions radial to the central axis of the beam must be characterized. In this study, we determined the difference in the central axis dose for spot-scanned fields that results from secondary particle doses by investigating energy deposition radial to the proton beam central axis resulting from primary protons and secondary particles for mathematical point source and distributed source models. The largest difference in the central axis dose from secondary particles resulting from the use of a mathematical point source and a distributed source model was approximately 0.43%. Thus, we conclude that the central axis dose for a spot-scanned field is effectively independent of the source model used to calculate the secondary particle dose. (paper)

  10. Task 3.0 - Advanced power systems. Subtask 3.18 - Ash behavior in power systems

    International Nuclear Information System (INIS)

    Zygarlicke, Christopher J.; Mccollor, Donald P.; Kay, John P.; Swanson, Michael L.

    1998-01-01

    The overall goal of this initiative is to develop fundamental knowledge of ash behavior in power systems for the purpose of increasing power production efficiency, reducing operation and maintenance costs, and reducing greenhouse gas emissions into the atmosphere. The specific objectives of this initiative focus primarily on ash behavior related to advanced power systems and include the following: Determine the current status of the fundamental ash interactions and deposition formation mechanisms as already reported through previous or ongoing projects at the EERC or in the literature. Determine sintering mechanisms for temperatures and particle compositions that are less well known and remain for the most part undetermined. Identify the relationship between the temperature of critical viscosity (T cv ) as measured in a viscometer and the crystallization occurring in the melt. Perform a literature search on the use of heated-stage microscopy (HSM) for examining in situ ash-sintering phenomena and then validate the use of HSM in the determination of viscosity in spherical ash particles. Ascertain the formation and stability of specific mineral or amorphous phases in deposits typical of advanced power systems. Evaluate corrosion for alloys being used in supercritical combustion systems

  11. The use of large surface area for particle and power deposition

    International Nuclear Information System (INIS)

    Seigneur, A.; Guilhem, D.; Hogan, J.

    1993-01-01

    Since the parallel heat flux passing through the LCFS has increased dramatically with the size of machines one has to cope with very large particle and power fluxes on the limiters. Thus the size of the limiters has been increased by the use of inner bumper limiters (for example in JET, TFTR, TORE-SUPRA and JT60). The 'exponential-sine' model is widely used to estimate the heat flux (Q) to a wall for a plasma flux surface with incident angle θ. The model predict Q = q || (0) sinθ e -ρ/λ q + q(0) cosθ e -ρ/λ q , (where θ=0 o when the flux surface is exactly tangential to the limiting surface), ρ is the minor radius measured from the last closed flux surface (LCFS), λ q is the SOL decay length of the heat flux density and q(0) is the heat flux density at the last closed surface. If we approximate the heat flux as Q = q || (0) e -ρ/λ q sin(θ+α), with α ≡ tan -1 [q(0)/q || (0)], then α can be interpreted as an effective 'minimum angle of incidence'. Under conditions where the geometric angle θ has been made almost grazing (below 5 o ) the predictions of the simplest model (with α=0 o ) is not adequate to represent the observation made in TORE-SUPRA; a similar result is found in TFTR. Experimental observations of heat and particle deposition on the large area limiter on the inner wall of TORE-SUPRA are presented. These results have been analyzed with a Monte Carlo code (THOR) describing the diffusion of hydrogenic particles across the LCFS to the limiting objects in the Scrape Off Layer (SOL), and by impurity generation calculations using the full 'exponential-sine' model (α ≠ 0) used as input to an impurity (carbon) Monte Carlo code (BBQ). (author) 6 refs., 3 figs., 1 tab

  12. Particle deposition and resuspension in gas-cooled reactors—Activity overview of the two European research projects THINS and ARCHER

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T., E-mail: t.barth@hzdr.de [Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Lecrivain, G. [Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Jayaraju, S.T. [Nuclear Research and Consultancy Group (NRG), 1755ZG Petten (Netherlands); Hampel, U. [Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering, Technische Universität Dresden, 01062 Dresden (Germany)

    2015-08-15

    Highlights: • A summary on particle deposition and resuspension experiments is provided. • Similarities between single and multilayer particle deposits are found. • Numerical models for simulation of particle deposits are successfully developed. - Abstract: The deposition and resuspension behaviour of radio-contaminated aerosol particles is a key issue for the safety assessment of depressurization accidents of gas-cooled high temperature reactors. Within the framework of two European research projects, namely Thermal Hydraulics of Innovative Nuclear Systems (THINS) and Advanced High-Temperature Reactors for Cogeneration of Heat and Electricity R&D (ARCHER), a series of investigations was performed to investigate the transport, the deposition and the resuspension of aerosol particles in turbulent flows. The experimental and numerical tests can be subdivided into four different parts: (1) Monolayer particle deposition, (2) Monolayer particle resuspension, (3) Multilayer particle deposition and (4) Multilayer particle resuspension. The experimental results provide a new insight into the formation and removal of aerosol particle deposits in turbulent flows and are used for the development and validation of numerical procedures in gas-cooled reactors. Good agreement was found between the numerical and the experimental results.

  13. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

  14. Characterization of Transient Receptor Potential Vanilloid-1 (TRPV1) Variant Activation by Coal Fly Ash Particles and Associations with Altered Transient Receptor Potential Ankyrin-1 (TRPA1) Expression and Asthma.

    Science.gov (United States)

    Deering-Rice, Cassandra E; Stockmann, Chris; Romero, Erin G; Lu, Zhenyu; Shapiro, Darien; Stone, Bryan L; Fassl, Bernhard; Nkoy, Flory; Uchida, Derek A; Ward, Robert M; Veranth, John M; Reilly, Christopher A

    2016-11-25

    Transient receptor potential (TRP) channels are activated by environmental particulate materials. We hypothesized that polymorphic variants of transient receptor potential vanilloid-1 (TRPV1) would be uniquely responsive to insoluble coal fly ash compared with the prototypical soluble agonist capsaicin. Furthermore, these changes would manifest as differences in lung cell responses to these agonists and perhaps correlate with changes in asthma symptom control. The TRPV1-I315M and -T469I variants were more responsive to capsaicin and coal fly ash. The I585V variant was less responsive to coal fly ash particles due to reduced translation of protein and an apparent role for Ile-585 in activation by particles. In HEK-293 cells, I585V had an inhibitory effect on wild-type TRPV1 expression, activation, and internalization/agonist-induced desensitization. In normal human bronchial epithelial cells, IL-8 secretion in response to coal fly ash treatment was reduced for cells heterozygous for TRPV1-I585V. Finally, both the I315M and I585V variants were associated with worse asthma symptom control with the effects of I315M manifesting in mild asthma and those of the I585V variant manifesting in severe, steroid-insensitive individuals. This effect may be due in part to increased transient receptor potential ankyrin-1 (TRPA1) expression by lung epithelial cells expressing the TRPV1-I585V variant. These findings suggest that specific molecular interactions control TRPV1 activation by particles, differential activation, and desensitization of TRPV1 by particles and/or other agonists, and cellular changes in the expression of TRPA1 as a result of I585V expression could contribute to variations in asthma symptom control. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Contribution to the study of tracheobronchial and pulmonary deposits in 52 subjects after inhalation of radioactive particles

    International Nuclear Information System (INIS)

    Lange, Pierre.

    1980-03-01

    Particle deposits in the bronchopulmonary system can lead to three main types of disorder: pneumoconioses, bronchial cancers and most chronic bronchopulmonary diseases. The study of deposition is useful for the prevention, diagnosis and treatment of these illnesses. The air-borne contaminants laid down are cleared by different mechanisms corresponding roughly to distinct anatomical regions. Short-term clearance, known as tracheobronchial (TB) takes place in a few hours, while long-term clearance from the deep lung is much slower: according to the International Radiological Protection Commission, 60% of particles deposited in the bronchiolo-alveolar region take more than 500 days to eliminate. It is useful therefore to known in what proportions the particles are fixed in the tracheobronchial region and on the deep lung. This was the purpose of the present work. The distribution of the deposit between these two regions was measured in 52 subjects having breathed in radioactive particles (indium 111). A functional respiratory study was conducted at the same time to find out whether the two sets of experimental data are related in any way [fr

  16. Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating

    DEFF Research Database (Denmark)

    Koivisto, Antti J.; Jensen, Alexander C. Ø.; Kling, Kirsten I.

    2017-01-01

    Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO2)-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m3 test chamber while measuring concentrations of 5.6nm ...

  17. Environmental factors controlling the seasonal variability in particle sizedistribution of modern Saharan dust deposited off Cape Blanc

    NARCIS (Netherlands)

    Friese, C.A.; van der Does, M.; Merkel, U.; Iversen, M.H.; Fischer, G.; Stuut, J-B W.

    2016-01-01

    The particle sizes of Saharan dust in marine sediment core records have been used frequently as a proxyfor trade-wind speed. However, there are still large uncertainties with respect to the seasonality of theparticle sizes of deposited Saharan dust off northwestern Africa and the factors influencing

  18. Theoretical calculations of the deposition of non-spherical particles in the upper airways of the human lung

    International Nuclear Information System (INIS)

    Sturm, Robert; Hofmann, Werner

    2009-01-01

    In the contribution presented here a computer model for the description of non-spherical particle deposition in the upper human respiratory tract is introduced. The theoretical approach is mainly based on the principle of the aerodynamic diameter, whose calculation was carried out according to most current scientific findings. With the help of this parameter deposition patterns for various particle categories (fibers and oblate disks) and breathing conditions (sitting, light-work and hard-work breathing) were simulated. Concerning cylindrical fibers with a diameter ≥ 1 μm, an increase of the aspect ratio β (i.e. particle length/particle diameter) causes a significant enhancement of deposition in the uppermost regions of the respiratory tract (oropharynx, larynx, trachea). This effect is additionally intensified by an increase of the inhalative flow. Regarding the oblate disks with a diameter ≥ 1 μm, any decrease of the aspect ratio leads to an enhancement of deposition in the deeper lung regions, representing an effect contrary to that observed for fibers. An increase of the inhalative flow only induces a limited decrease of the effect. (orig.)

  19. Deposition, translocation and effects of transuranic particles inhaled by experimental animals

    International Nuclear Information System (INIS)

    Craig, D.K.; Ballou, J.E.; Dagle, G.E.; Mahlum, D.D.; Park, J.F.; Sanders, C.L.; Sikov, M.R.; Stuart, B.O.

    1977-01-01

    Inhalation exposure constitutes the most likely route of entrance for transuranics into the body. Cancer is the most likely consequence of exposure, but several thousand workers have been exposed during the last 30 yrs without, so far, evidence of exposure-related effects. Several soluble and insoluble transuranic compounds have been studied in rodents and dogs, either alone or combined with exposure to other materials (e.g., PuO/sub 2/--UO/sub 2/ fuel and Na). These studies have provided a wide variety of spatial and temporal dose distribution patterns in the lung. The distribution and total initial deposition in the respiratory tract is a function of the physical characteristics of the inhaled aerosols (size distribution, shape, hygroscopicity) and of the morphology and physiology of the animal. Translocation rates, organ and tissue distribution and excretion in urine and feces, are a function of the physicochemical characteristics of the deposited material (solubility, specific activity, chemical compound, etc.). Differences in rate of translocation of the solubilized material, primarily to the liver and bone, determines the radiation dose to the various tissues involved. Insoluble particles of plutonium dioxide are transferred to the thoracic lymph nodes, which may be functionally destroyed as a consequence. Radiation pneumonitis and pulmonary fibrosis are the main causes of death in animals with cumulative radiation doses to the lung of a few thousand rads. The most significant long-term effect of inhaled transuranic compounds in animals is the development of lung and bone tumors. The main type of lung tumor in both dog and rat is the bronchioloalveolar carcinoma (adenocarcinoma). However, tumor type is a function of radiation dose and dose-distribution at high doses. Bone ranks next to lung as the tissue developing the most tumors following inhalation of transuranics

  20. Deposition, translocation, and effects of transuranic particles inhaled by experimental animals

    International Nuclear Information System (INIS)

    Craig, D.K.; Ballou, J.E.; Dagle, G.E.; Mahlum, D.D.; Park, J.F.; Sanders, C.L.; Sikov, M.R.; Stuart, B.O.

    1977-01-01

    Inhalation exposure constitutes the most likely route of entrance for transuranics into the body. Cancer is the most likely consequence of exposure, but several thousand workers have been exposed during the last 30 yrs without, so far, evidence of exposure-related effects. Several soluble and insoluble transuranic compounds have been studied in rodents and dogs, either alone or combined with exposure to other materials (e.g., PuO 2 --UO 2 fuel and Na). These studies have provided a wide variety of spatial and temporal dose distribution patterns in the lung. The distribution and total initial deposition in the respiratory tract is a function of the physical characteristics of the inhaled aerosols (size distribution, shape, hygroscopicity) and of the morphology and physiology of the animal. Translocation rates, organ and tissue distribution and excretion in urine and feces, are a function of the physicochemical characteristics of the deposited material (solubility, specific activity, chemical compound, etc.). Differences in rate of translocation of the solubilized material, primarily to the liver and bone, determines the radiation dose to the various tissues involved. Insoluble particles of plutonium dioxide are transferred to the thoracic lymph nodes, which may be functionally destroyed as a consequence. Radiation pneumonitis and pulmonary fibrosis are the main causes of death in animals with cumulative radiation doses to the lung of a few thousand rads. The most significant long-term effect of inhaled transuranic compounds in animals is the development of lung and bone tumors. The main type of lung tumor in both dog and rat is the bronchioloalveolar carcinoma (adenocarcinoma). However, tumor type is a function of radiation dose and dose-distribution at high doses. Bone ranks next to lung as the tissue developing the most tumors following inhalation of transuranics

  1. Release of microspherolites and metals extraction from energetical fly ashes by Bacillus isolates

    Directory of Open Access Journals (Sweden)

    Štyriaková Iveta

    2000-09-01

    Full Text Available The amorphous secondary silicate mineral components formed in the process of coal combustion dominate in the composition of energy fly-ash. Depending on the composition of coal concentrate, this secondary raw material source also contains the industrially interesting components, e.g. titanium (eventually iron and aluminium and can be considered as a non-metallic material suitable for the construction industry.The main secondary mineral components of the energy fly-ash formed during the coal combustion were studied using SEM (scanning electronic microscope. They can be divided into four groups:1. Amorphous spherical alumocilicate particles in allotriomorphic aluminosilicate grains – they represent a main mineral component of fly-ash, which is formed from the accompanying rocks of coal containing silicate minerals,2. Quartz – which formed a substantial component of accompanying rocks of coal or accompanying accessory mineral of coal together with kaolinite and mica, was transformed into tridymite at the temperature exceeding 870°C and into cristobalite at the temperature exceeding 1470°C. The spherical particles are products of reaction between cristobalite and aluminosilicate, which is a frequent phenomenon occurring during the formation of volcanic rocks. These particles form together a main amorphous phase of fly-ash.3. Mullite – represents a secondary component of fly-ash, which is formed from accompanying clay minerals of coal (kaolinite, mica together with cristobalite under the effect of temperature exceeding 1150°C,4. Non-combusted residue – consists of organic substance, represents a non-combusted ratio of coal as a secondary component of fly-ash.Heterotrophic bacteria of Bacillus genus are capable to remove 66 % of titanium and 33 % of iron from non-deposited fly-ash from Opatovice after 35 days of leaching of samples. The content of solid phase in fly-ash influences the extraction of elements, mainly iron and titatnium, because

  2. Influence of the particle morphology on the Cold Gas Spray deposition behaviour of titanium on aluminum light alloys

    International Nuclear Information System (INIS)

    Cinca, N.; Rebled, J.M.; Estradé, S.; Peiró, F.; Fernández, J.; Guilemany, J.M.

    2013-01-01

    Highlights: ► Study of the particle–substrate and particle–particle interfaces in the cold spray process. ► Use of irregular feedstock particles whereas normally FIB studies have been undergone for spherical particles. ► Deep Transmission Electron Microscopy characterization of the interfaces and within the particle. -- Abstract: The present work evaluates the deposition behaviour of irregular titanium powder particles impinged by Cold Gas Spraying onto an aluminium 7075-T6 alloy substrate. The influence of their irregular shape on the bonding phenomena, in particle–substrate and particle–particle interfaces are discussed in view of Transmission Electron Microscopy examinations of a Focused Ion Beam lift-out prepared sample. Key aspects will be the jetting-out, the occurrence of oxide layers and grain size refinement. Different structural morphologies could be featured; at the particle–substrate interface, both the aluminium alloy and the titanium side exhibit recrystallization. Titanium particles in intimate contact in small agglomerates during deposition, on the other hand, show grain refinement at their interfaces whereas the original structure is maintained outside those boundaries

  3. Hierarchically structured superhydrophobic coatings fabricated by successive Langmuir-Blodgett deposition of micro-/nano-sized particles and surface silanization.

    Science.gov (United States)

    Tsai, Ping-Szu; Yang, Yu-Min; Lee, Yuh-Lang

    2007-11-21

    The present study demonstrates the creation of a stable, superhydrophobic surface by coupling of successive Langmuir-Blodgett (LB) depositions of micro- and nano-sized (1.5 µm/50 nm, 1.0 µm/50 nm, and 0.5 µm/50 nm) silica particles on a glass substrate with the formation of a self-assembled monolayer of dodecyltrichlorosilane on the surface of the particulate film. Particulate films, in which one layer of 50 nm particles was deposited over one to five sublayers of larger micro-sized particles, with hierarchical surface roughness and superhydrophobicity, were successfully fabricated. Furthermore, the present 'two-scale' (micro- and nano-sized particles) approach is superior to the previous 'one-scale' (micro-sized particles) approach in that both higher advancing contact angle and lower contact angle hysteresis can be realized. Experimental results revealed that the superhydrophobicity exhibited by as-fabricated particulate films with different sublayer particle diameters increases in the order of 0.5 µm>1.0 µm>1.5 µm. However, no clear trend between sublayer number and surface superhydrophobicity could be discerned. An explanation of superhydrophobicity based on the surface roughness introduced by two-scale particles is also proposed.

  4. Real-time mass measurement of dust particles deposited on vessel wall in a divertor simulator using quartz crystal microbalances

    International Nuclear Information System (INIS)

    Tateishi, Mizuki; Koga, Kazunori; Katayama, Ryu; Yamashita, Daisuke; Kamataki, Kunihiro; Seo, Hyunwoong; Itagaki, Naho; Shiratani, Masaharu; Ashikawa, Naoko; Masuzaki, Suguru; Nishimura, Kiyohiko; Sagara, Akio

    2015-01-01

    We are developing a dust monitoring method using quartz crystal microbalances (QCMs) equipped with a dust eliminating filter. Here we report a dust eliminating ratio of the filter and first measurement results of the QCMs in a divertor simulator. The volume of spherical dust in unit area on the filter and QCM under the filter were 2.09 × 10 −9 and 1.22 × 10 −10 m 3 m −2 , respectively. Thus, the dust eliminating ratio of the filter is 94.2%. The QCM without the filter gives deposition rate due to radicals and dust particles, whereas the QCM with the filter gives deposition rate predominantly due to radicals. From the results, we deduce information of mass fraction of dust particles in deposits

  5. Radiative effects of light-absorbing particles deposited in snow over Himalayas using WRF-Chem simulations

    Science.gov (United States)

    Sarangi, C.; Qian, Y.; Painter, T. H.; Liu, Y.; Lin, G.; Wang, H.

    2017-12-01

    Radiative forcing induced by light-absorbing particles (LAP) deposited on snow is an important surface forcing. It has been debated that an aerosol-induced increase in atmospheric and surface warming over Tibetan Plateau (TP) prior to the South Asian summer monsoon can have a significant effect on the regional thermodynamics and South Asian monsoon circulation. However, knowledge about the radiative effects due to deposition of LAP in snow over TP is limited. In this study we have used a high-resolution WRF-Chem (coupled with online chemistry and snow-LAP-radiation model) simulations during 2013-2014 to estimate the spatio-temporal variation in LAP deposition on snow, specifically black carbon (BC) and dust particles, in Himalayas. Simulated distributions in meteorology, aerosol concentrations, snow albedo, snow grain size and snow depth are evaluated against satellite and in-situ measurements. The spatio-temporal change in snow albedo and snow grain size with variation in LAP deposition is investigated and the resulting shortwave LAP radiative forcing at surface is calculated. The LAP-radiative forcing due to aerosol deposition, both BC and dust, is higher in magnitude over Himalayan slopes (terrain height below 4 km) compared to that over TP (terrain height above 4 km). We found that the shortwave aerosol radiative forcing efficiency at surface due to increase in deposited mass of BC particles in snow layer ( 25 (W/m2)/ (mg/m2)) is manifold higher than the efficiency of dust particles ( 0.1 (W/m2)/ (mg/m2)) over TP. However, the radiative forcing of dust deposited in snow is similar in magnitude (maximum 20-30 W/m2) to that of BC deposited in snow over TP. This is mainly because the amount of dust deposited in snow over TP can be about 100 times greater than the amount of BC deposited in snow during polluted conditions. The impact of LAP on surface energy balance, snow melting and atmospheric thermodynamics is also examined.

  6. Study and characterization of an integrated circuit-deposited hydrogenated amorphous silicon sensor for the detection of particles and radiations

    International Nuclear Information System (INIS)

    Despeisse, M.

    2006-03-01

    Next generation experiments at the European laboratory of particle physics (CERN) require particle detector alternatives to actual silicon detectors. This thesis presents a novel detector technology, which is based on the deposition of a hydrogenated amorphous silicon sensor on top of an integrated circuit. Performance and limitations of this technology have been assessed for the first time in this thesis in the context of particle detectors. Specific integrated circuits have been designed and the detector segmentation, the interface sensor-chip and the sensor leakage current have been studied in details. The signal induced by the track of an ionizing particle in the sensor has been characterized and results on the signal speed, amplitude and on the sensor resistance to radiation are presented. The results are promising regarding the use of this novel technology for radiation detection, though limitations have been shown for particle physics application. (author)

  7. Influence of anionic stabilization of alumina particles in 2-propanol medium on the electrophoretic deposition and mechanical properties of deposits

    Czech Academy of Sciences Publication Activity Database

    Drdlík, D.; Bartoníčková, E.; Hadraba, Hynek; Cihlář, J.

    2014-01-01

    Roč. 34, č. 14 (2014), s. 3365-3371 ISSN 0955-2219 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Anionic stabilization * Electric conductivity * Alumina * Electrophoretic deposition Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.947, year: 2014

  8. Characterization of ashes from biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, F.J.; Hansen, L.A. [Technical Univ. of Denmark. Dept. of Chemical Engineering (Denmark); Soerensen, H.S. [Geological Survey of Denmark and Greenland (Denmark); Hjuler, K. [dk-TEKNIK. Energy and Environment (Denmark)

    1998-02-01

    One motivation for initiating the present project was that the international standard method of estimating the deposit propensity of solid fuels, of which a number of variants exist (e.g. ISO, ASTM, SD, DIN), has shown to be unsuitable for biomass ashes. This goal was addressed by the development of two new methods for the detection of ash fusibility behaviour based on Simultaneous Thermal Analysis (STA) and High Temperature Light Microscopy (HTLM), respectively. The methods were developed specifically for ashes from biofuels, but are suitable for coal ashes as well. They have been tested using simple salt mixtures, geological standards and samples from straw CHP and coal-straw PF combustion plants. All samples were run in a nitrogen atmosphere at a heating rate of 10 deg. C/min. In comparison with the standard method, the new methods are objective and have superior repeatability and sensitivity. Furthermore, the two methods enable the melting behavior to be characterized by a continuous measurement of melt fraction versus temperature. Due to this two-dimensional resolution of the results, the STA and HTLM methods provide more information than the standard method. The study of bottom ash and fly ash as well as deposit samples from straw test firings at the Haslev and Slagelse Combined Heat and Power plants resulted in a better understanding of mineral behaviour during straw grate firing. In these tests a number of straws were fired which had been carefully selected for having different qualities with respect to sort and potassium and chlorine contents. By studying bottom ashes from Slagelse it was found that the melting behaviour correlated with the deposition rate on a probe situated at the outlet part of the combustion zone. (EG)

  9. Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

    Science.gov (United States)

    Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

    2015-12-01

    Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition.

  10. EFFECT OF CENTRAL FANS AND IN-DUCT FILTERS ON DEPOSITION RATES OF ULTRAFINE AND FINE PARTICLES IN AN OCCUPIED TOWNHOUSE

    Science.gov (United States)

    Airborne particles are implicated in morbidity and mortality of certain high-risk subpopulations. Exposure to particles occurs mostly indoors, where a main removal mechanism is deposition to surfaces. Deposition can be affected by the use of forced- air circulation through duct...

  11. An analysis of impact on the environmental pollution under accident conditions due to the disposal of ashes from the Nikola Tesla B thermal power plant

    International Nuclear Information System (INIS)

    Milovanovic, D.; Zlvkovic, Z.

    1996-01-01

    The ash disposal area of Nikola Tesla B TPP is presenting considerable potential source of environmental pollution. Due to its vast area, that is for an effective plot of about 400 ha, under unfavorable meteorological conditions the emerging of ash cloud spreading over the surrounding area at distances of over 15 km could be produced. This paper deals with accident conditions at ash disposal area which, after stopping of sprinkling operation or in case of an inadequate sequence of ash tapping, when larger portions of disposal area are dried, turn into area of air polluting sources. Computations of particle dispersions under such conditions have been performed for different meteorological conditions and the results are represented as space distribution of particle deposition on the soil and their concentration in the air. (author). 5 figs., 4 refs

  12. The comparative analysis of heat transfer efficiency in the conditions of formation of ash deposits in the boiler furnaces, with taking into account the crystallization of slag during combustion of coal and water-coal fuel

    Science.gov (United States)

    Salomatov, V. V.; Kuznetsov, G. V.; Syrodoy, S. V.

    2017-11-01

    The results of the numerical simulation of heat transfer from the combustion products of coal and coal-water fuels (CWF) to the internal environment. The mathematical simulation has been carried out on the sample of the pipe surfaces of the combustion chamber of the boiler unit. The change in the characteristics of heat transfer (change of thermochemical characteristics) in the conditions of formation of the ash deposits have been taken into account. According to the results of the numerical simulation, the comparative analysis of the efficiency of heat transfer has been carried out from the furnace environment to the inside pipe coolant (water, air, or water vapor) from the combustion of coal and coal-water fuels. It has been established that, in the initial period of the boiler unit operation during coal fuel combustion the efficiency of heat transfer from the combustion products of the internal environment is higher than when using CWF. The efficiency of heat transfer in CWF combustion conditions is more at large times (τ≥1.5 hours) of the boiler unit. A significant decrease in heat flux from the combustion products to the inside pipe coolant in the case of coal combustion compared to CWF has been found. It has been proved that this is due primarily to the fact that massive and strong ash deposits are formed during coal combustion.

  13. Characterization of Montserrat volcanic ash for the assessment of respiratory health hazards

    International Nuclear Information System (INIS)

    Horwell, Claire Judith

    2002-01-01

    Volcanic ash, generated in the long-lived eruption of the Soufriere Hills volcano, Montserrat, is shown to contain respirable (sub-4 μm) particles and the crystalline silica polymorph, cristobalite. Respirable particles of cristobalite can cause silicosis, raising the possibility that volcanic ash is a respiratory health hazard. This study considers some of the main factors that affect human exposure to volcanic particles: the composition, proportions and surface reactivity of respirable ash and the composition and concentrations of re-worked and airborne suspended particulates. Dome-collapse ash-fall deposits are significantly richer in respirable particles (12 weight %) than the other tephra samples, in particular the matrices of dome-collapse pyroclastic-flow deposits (3 weight %). Within the respirable fraction, dome-collapse ash contains the highest proportion of crystalline silica particles (20-27 number %, of which 97 % is cristobalite), compared with other primary tephra types (0.4-5.6 number %). The results are explained by significant fractionation during fragmentation of pyroclastic flows due to the size and strength of particles and the selective elutriation of fines into the lofting ash plume. This result in a fines-depleted dome-collapse matrix and a fines-rich dome-collapse ash deposit. For all sample types, the sub-4 μm fraction comprises 45-55 weight % of the sub-10 μm fraction. Re-worked and airborne samples show enrichment of crystalline silica in the respirable fraction (10-18 number %) but have low proportions of respirable ash (∼ 3 weight %) compared to primary ash samples. The concentration of ash particles re-suspended by road vehicles on Montserrat is found to decrease exponentially with height above the ground, indicating higher exposure for children compared with adults: PM 4 concentration at 0.9 m (height of two year old child) is three times that at 1.8m (adult height). Surface- and free-radical production has been closely linked

  14. Characterization of Montserrat volcanic ash for the assessment of respiratory health hazards

    Energy Technology Data Exchange (ETDEWEB)

    Horwell, Claire Judith

    2002-07-01

    Volcanic ash, generated in the long-lived eruption of the Soufriere Hills volcano, Montserrat, is shown to contain respirable (sub-4 {mu}m) particles and the crystalline silica polymorph, cristobalite. Respirable particles of cristobalite can cause silicosis, raising the possibility that volcanic ash is a respiratory health hazard. This study considers some of the main factors that affect human exposure to volcanic particles: the composition, proportions and surface reactivity of respirable ash and the composition and concentrations of re-worked and airborne suspended particulates. Dome-collapse ash-fall deposits are significantly richer in respirable particles (12 weight %) than the other tephra samples, in particular the matrices of dome-collapse pyroclastic-flow deposits (3 weight %). Within the respirable fraction, dome-collapse ash contains the highest proportion of crystalline silica particles (20-27 number %, of which 97 % is cristobalite), compared with other primary tephra types (0.4-5.6 number %). The results are explained by significant fractionation during fragmentation of pyroclastic flows due to the size and strength of particles and the selective elutriation of fines into the lofting ash plume. This result in a fines-depleted dome-collapse matrix and a fines-rich dome-collapse ash deposit. For all sample types, the sub-4 {mu}m fraction comprises 45-55 weight % of the sub-10 {mu}m fraction. Re-worked and airborne samples show enrichment of crystalline silica in the respirable fraction (10-18 number %) but have low proportions of respirable ash ({approx} 3 weight %) compared to primary ash samples. The concentration of ash particles re-suspended by road vehicles on Montserrat is found to decrease exponentially with height above the ground, indicating higher exposure for children compared with adults: PM{sub 4} concentration at 0.9 m (height of two year old child) is three times that at 1.8m (adult height). Surface- and free-radical production has been

  15. Passivation of pigment-grade TiO2 particles by nanothick atomic layer deposited SiO2 films

    International Nuclear Information System (INIS)

    King, David M; Liang Xinhua; Weimer, Alan W; Burton, Beau B; Akhtar, M Kamal

    2008-01-01

    Pigment-grade TiO 2 particles were passivated using nanothick insulating films fabricated by atomic layer deposition (ALD). Conformal SiO 2 and Al 2 O 3 layers were coated onto anatase and rutile powders in a fluidized bed reactor. SiO 2 films were deposited using tris-dimethylaminosilane (TDMAS) and H 2 O 2 at 500 deg. C. Trimethylaluminum and water were used as precursors for Al 2 O 3 ALD at 177 deg. C. The photocatalytic activity of anatase pigment-grade TiO 2 was decreased by 98% after the deposition of 2 nm SiO 2 films. H 2 SO 4 digest tests were performed to exhibit the pinhole-free nature of the coatings and the TiO 2 digest rate was 40 times faster for uncoated TiO 2 than SiO 2 coated over a 24 h period. Mass spectrometry was used to monitor reaction progress and allowed for dosing time optimization. These results demonstrate that the TDMAS-H 2 O 2 chemistry can deposit high quality, fully dense SiO 2 films on high radius of curvature substrates. Particle ALD is a viable passivation method for pigment-grade TiO 2 particles

  16. Synthesis of nano-composite surfaces via the co-deposition of metallic salts and nano particles

    Energy Technology Data Exchange (ETDEWEB)

    MacFarlane, J.W.; Tesh, S.J.; Crane, R.A.; Hallam, K.R.; Scott, T.B.

    2014-03-15

    Highlights: • Nanofaceted surfaces are prepared by a low current density (<0.1 A cm{sup 2}) electrodeposition method. • Surfaces are formed of nanoparticles anchored to a conductive (carbon) substrate. • Formed surfaces show a high nano-reactivity and surface area. • Demonstration of INP/FeCl{sub 3} nanocomposite for water filtration effectively removing BTEX contamination. -- Abstract: A novel, low energy method for coating different nano-particles via electro-deposition to a recyclable carbon glass supporting structure is demonstrated. In the resulting composite, the nano-material is bound to the substrate surface, thereby removing the potential for causing harmful interactions with the environment. Nano-particles were suspended in a salt solution and deposited at low current densities (<0.1 A cm{sup −2}) producing thin (<100 nm), uniform nano-faceted surfaces. A co-deposition mechanism of nano-particles and cations from the salt solution is proposed and explored. This has been successfully demonstrated for iron, sliver, titanium in the current work. Furthermore, the removal of the surface coatings can be achieved via a reversed current applied over the system, allowing for the recovery of surface bound metal contaminants. The demonstrated applicability of this coating method to different nano-particle types, is useful in many areas within the catalysis and water treatment industries. One such example, is demonstrated, for the treatment of BTEX contamination and show a greatly improved efficiency to current leading remediation agents.

  17. Particle deposition on face-up flat plates in parallel airflow under the combined influences of thermophoresis and electrophoresis

    International Nuclear Information System (INIS)

    Lee, Handol; Yook, Sejin; Han, Seogyoung

    2012-01-01

    The deposition velocity is used to assess the degree of particulate contamination of wafers or photomasks. A numerical model was developed to predict the deposition velocity under the combined influences of thermophoresis and electrophoresis. The deposition velocity onto a face-up flat plate in parallel airflow was simulated by varying the temperature difference between the plate's surface and ambient air or by changing the strength of the electric field established above the plate. Both attraction and repulsion by thermophoresis or electrophoresis were considered. When the plate's surface was colder than ambient air, the surface of the face-up plate could be at risk of contamination by charged particles even with a repulsive applied electric force. When the temperature of the plate's surface was higher than the ambient temperature, the degree of particulate contamination on the surface of the face-up plate could be remarkably reduced in the presence of an electric field. The effect of repulsive thermophoresis, however, is expected to be reduced for very fine particles of high electric mobility or for micrometer-sized particles with large gravitational settling speed when the charged particles are influenced by an attractive electric force.

  18. Cluster-guided imaging-based CFD analysis of airflow and particle deposition in asthmatic human lungs

    Science.gov (United States)

    Choi, Jiwoong; Leblanc, Lawrence; Choi, Sanghun; Haghighi, Babak; Hoffman, Eric; Lin, Ching-Long

    2017-11-01

    The goal of this study is to assess inter-subject variability in delivery of orally inhaled drug products to small airways in asthmatic lungs. A recent multiscale imaging-based cluster analysis (MICA) of computed tomography (CT) lung images in an asthmatic cohort identified four clusters with statistically distinct structural and functional phenotypes associating with unique clinical biomarkers. Thus, we aimed to address inter-subject variability via inter-cluster variability. We selected a representative subject from each of the 4 asthma clusters as well as 1 male and 1 female healthy controls, and performed computational fluid and particle simulations on CT-based airway models of these subjects. The results from one severe and one non-severe asthmatic cluster subjects characterized by segmental airway constriction had increased particle deposition efficiency, as compared with the other two cluster subjects (one non-severe and one severe asthmatics) without airway constriction. Constriction-induced jets impinging on distal bifurcations led to excessive particle deposition. The results emphasize the impact of airway constriction on regional particle deposition rather than disease severity, demonstrating the potential of using cluster membership to tailor drug delivery. NIH Grants U01HL114494 and S10-RR022421, and FDA Grant U01FD005837. XSEDE.

  19. Assessment of the exposure of islanders to ash from the Soufriere Hills volcano, Montserrat, British West Indies.

    Science.gov (United States)

    Searl, A; Nicholl, A; Baxter, P J

    2002-08-01

    The Soufriere Hills volcano, Montserrat, has been erupting since July 1995 and volcanic ash has fallen on the island throughout most of the eruption. The ash contains substantial quantities of respirable particles and unusually large amounts (15-20%) of the crystalline silica mineral, cristobalite. The purpose of the surveys described here, undertaken between December 1996 and April 2000, was to determine levels of personal exposure of islanders to volcanic ash and cristobalite in order to inform advice on the associated risks to health and the measures required to reduce exposure. Surveys of personal exposure to respirable dust and cristobalite were undertaken using cyclone samplers. In addition, direct reading instruments (DUSTTRAK) were used to monitor ambient air concentrations of PM(10) at fixed sites and also to provide information about exposures to airborne particles associated with selected activities. Environmental concentrations of airborne ash have been greatest in the areas where the most ash has been deposited and during dry weather. Individual exposure to airborne ash was related to occupation, with the highest exposures among gardeners, cleaners, roadworkers, and police at roadside checkpoints. During 1997 many of these individuals were exposed to concentrations of cristobalite that exceeded the ACGIH recommended occupational exposure limit. Since the population became confined to the north of the island in October 1997, even those in relatively dusty occupations have received exposures to cristobalite well below this limit. Most of the 4500 people who have remained on island since the eruption began have not been exposed to sufficiently high concentrations of airborne dust for long enough to be at risk of developing silicosis. However, more than a dozen individuals continued to experience frequent high occupational exposures to volcanic ash, some of whom may have had sufficient exposure to crystalline silica to be at risk of developing mild

  20. Effect of mechanical activation of fly ash added to Moroccan Portland cement

    Directory of Open Access Journals (Sweden)

    Ez-zaki H.

    2018-01-01

    This study aims to investigate the influence of grinding fly ash on the physico-chemical and mechanical properties of fly ash blended CPJ45 cement. The addition of the fly ash particles to the grinder leads respectively to the breakage of the particles and to reduce the agglomeration effect in the balls of cement grinder. Fly ash milling was found to improve particles fineness, and increase the silica and alumina content in the cement. Furthermore, milled fly ash blended cements show higher compressive strength compared to unmilled fly ash blended cements, due to improved fly ash reactivity through their mechanical activation.

  1. Mathematical Model of Transfer and Deposition of Finely Dispersed Particles in a Turbulent Flow of Emulsions and Suspensions

    Science.gov (United States)

    Laptev, A. G.; Basharov, M. M.

    2018-05-01

    The problem of modeling turbulent transfer of finely dispersed particles in liquids has been considered. An approach is used where the transport of particles is represented in the form of a variety of the diffusion process with the coefficient of turbulent transfer to the wall. Differential equations of transfer are written for different cases, and a solution of the cell model is obtained for calculating the efficiency of separation in a channel. Based on the theory of turbulent transfer of particles and of the boundary layer model, an expression has been obtained for calculating the rate of turbulent deposition of finely dispersed particles. The application of this expression in determining the efficiency of physical coagulation of emulsions in different channels and on the surface of chaotic packings is shown.

  2. Nanotune: A Novel Approach to Control the Deposition and Fate of Particles in Porous Media

    Science.gov (United States)

    Sethi, R.; Bianco, C.; Tosco, T.; Tiraferri, A.; Patiño Higuita, J. E.

    2017-12-01

    Nanoremediation is an innovative environmental nanotechnology aimed at reclaiming contaminated aquifers. It consists in the subsurface injection of a reactive colloidal suspension for the in-situ treatment of pollutants. The greatest challenges faced by engineers to advance nanoremediation are the effective delivery and the appropriate dosing of the nanoparticles into the subsoil. These are necessary for the correct emplacement of the in situ reactive zone and to minimize the overall cost of the reclamation and the potential secondary risks associated to the uncontrolled migration of the injected particles. In this study, a model assisted strategy, NanoTune, is developed to control the distribution of colloids in porous media. The proposed approach consists in the sequential injection of a stable suspension of reactive nanoparticles and of a destabilizing agent with the aim of creating a reactive zone within a targeted portion of the contaminated aquifer. The controlled and irreversible deposition of the particles is achieved by inducing the mixing of the two fluids in the desired portion of the aquifer. This approach is here exemplified by the delivery of humic acid-stabilized iron oxide nanoparticles (FeOx), a typical reagent for in situ immobilization of heavy metals. Divalent cations, which are known to cause rapid aggregation of the suspension because of their strong interaction with the humic acid coating, are used as destabilizing agents. The injection strategy is here applied in 1D columns to create a reactive zone for heavy metal removal in the central region of the sandy bed. The software MNMs was used to assess the correct sequence and duration of the injection of the different solutions in the 1D medium. Moreover, the numerical code MNM3D (MNM3D - Micro and Nanoparticle transport Model in 3D geometries) was developed by the authors of this work to support the case-specific design of the injection strategy during field scale applications. The Nano

  3. MICROSTRUCTURE, MINERALOGY AND PHYSICAL PROPERTIES OF GROUND FLY ASH BASED GEOPOLYMERS

    Directory of Open Access Journals (Sweden)

    Ferenc Madai

    2015-03-01

    Full Text Available This paper is focused on the utilization of deposited fly ash as a main component of geopolymer. After determination of particle size distribution, moisture content, real and bulk density and specific surface area of the raw fly ash, mechanical activation was performed by laboratory scale ball mill. This step is introduced for improving the reactivity of raw material. Then test specimens were produced by geopoliomerisation using a caustic spent liquor (NaOH. Compressive strength was determined on cilindrical specimens. Finally, samples of the ground fly ash based geopolymer specimens were analyzed by X-ray diffraction, optical and scanning electron microscopy. Results prove that geopolymer production with proper strength from the investigated F-type deposited fly ash is possible. The uniaxial compressive strength of obtained composites strongly depends on the fineness of the ground fly ash. XRD results show that comparing the crystalline components for different geopolymer samples, zeolite-A appears and its amount increases gradually from 0T sample till 30T and then decreases for 60T sample. The same trend holds for sodalite type structure phases, however its amount is much lower than for zeolite-A. SEM+EDS investigation revealed that Na-content is elevated in the interstitial fine-grained matrix, especially for the 30T sample when highest strength was observed. Si and Al are abundant mainly in anhedral and spherical grains and in rarely occurring grains resembling some crystal shape.

  4. Experimentally Investigating the Effect of Temperature Differences in the Particle Deposition Process on Solar Photovoltaic (PV Modules

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2016-10-01

    Full Text Available This paper reports an experimental investigation of the dust particle deposition process on solar photovoltaic (PV modules with different surface temperatures by a heating plate to illustrate the effect of the temperature difference (thermophoresis between the module surface and the surrounding air on the dust accumulation process under different operating temperatures. In general, if the temperature of PV modules is increased, the energy conversion efficiency of the modules is decreased. However, in this study, it is firstly found that higher PV module surface temperature differences result in a higher energy output compared with those modules with lower temperature differences because of a reduced accumulation of dust particles. The measured deposition densities of dust particles were found to range from 0.54 g/m2 to 0.85 g/m2 under the range of experimental conditions and the output power ratios were found to increase from 0.861 to 0.965 with the increase in the temperature difference from 0 to 50 °C. The PV module with a higher temperature difference experiences a lower dust density because of the effect of the thermophoresis force arising from the temperature gradient between the module surface and its surrounding air. In addition, dust particles have a significant impact on the short circuit current, as well as the output power. However, the influence of particles on open circuit voltage can be negligible.

  5. Deposition behavior of polystyrene latex particles on solid surfaces during migration through an artificial fracture in a granite rock sample

    International Nuclear Information System (INIS)

    Chinju, Hirofumi; Tanaka, Satoru; Kuno, Yoshio

    2001-01-01

    The deposition behavior of colloids during transport through heterogeneous media was observed by conducting column experiments to study migration of polystyrene latex particles (diameter=309 nm) through columns packed with artificially fractured granite rock (length=300 and 150 mm). The experiments were conducted under conditions of different ionic strengths and flow rates. The results were similar to those for colloid deposition in columns packed with glass beads reported previously; the colloid breakthrough curves showed three stages, characterized by different rates of change in the concentration of effluent. Colloid deposition on the fracture surfaces was described by considering strong and weak deposition sites. Scanning Electron Microscopy (SEM) observations indicated the existence of strong and weak sites on the fracture surfaces regardless of mineral composition. The observations also showed that the strong deposition sites tended to exist on surface irregularities such as cracks or protrusions. The degree of colloid deposition increased with increasing ionic strength and decreasing flow rate. The dependencies on ionic strength and flow rate agreed qualitatively with the DLVO theory and the previous experimental results, respectively. (author)

  6. Greenlandic Waste Incineration Fly And Bottom Ash As Secondary Resource In Mortar

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.; Jensen, Pernille Erland

    2016-01-01

    Today, 900 tons incineration fly ash is shipped abroad annually from Greenland for deposits, whereas the 6,000 tons incineration bottom ash is deposited locally. These incineration ashes could be valuable in concrete production, where the cement has to be shipped to Greenland. For this purpose...... and cement with fly ash. Based on the compressive strength tests, it is found that using Greenlandic incineration ashes in mortar as 5% cement replacement could consume all ash instead of disposals, and could thus turn the ashes into a local resource and simultaneously reduce the import of cement....

  7. Regional monitoring of metals in the Munich metropolitan area: Comparison of biomonitoring (standardized grass culture) with deposition and airborne particles

    International Nuclear Information System (INIS)

    Dietl, C.; Reifenhaeuser, W.; Vierle, O.; Peichl, L.; Faus-Kessler, Th.

    2000-01-01

    In the Munich metropolitan area a close association of lead (Pb) and antimony (Sb) impacts with traffic was observed in 1992 and 1993. The intercorrelation of both metals was found by samples of standardised grass cultures and was reflected by deposition sampling, too. With respect to location-specific variations, however, both methods revealed differing gradients of Pb and Sb concentrations with increasing distance from traffic. It appeared that Sb variations according to traffic implications were particularly well indicated by means of biomonitoring, while Pb variations were not indicated adequately. As a result, a special qualification of grass to selectively collect metals on airborne dust according to particle sizes was suggested. Further investigations on the correlations between metal biomonitoring, metal deposition and airborne metals in 1994 - 1996 corroborated method-specific sampling features. They in turn showed that one interference is the individual prevalence of the metals on different particle sizes. (author)

  8. The effect of bed particle size and deposit morphology on the filtration of magnetite through granular graphite beds

    International Nuclear Information System (INIS)

    Barbieri, R.R.; Bercovich, E.J.; Liberman, S.J.

    1980-01-01

    Graphite filters are of great interest for water purification in nuclear power reactors' primary systems due to their possible operation at high temperature. The influence of the bed particle size on the retention of magnetite from aqueous suspensions at room temperature was studied. The filtration coefficient changes from 0.0 to 0.18 as the mean graphite particle diameter decreases from 1.2 to 0. mm. As the retention increases, there is also an increase in the differential pressure across the bed, so both effects must be considered in order to optimize filter's operation. The specific effective volume of the deposit was calculated with the Blake-Kozeny equation and the experimental specific volumes. These are much larger than the specific volume of solid magnetite. From the results, information regarding the morphology of the deposit in the filter is obtained. (M.E.L) [es

  9. Interactions of animal age and particle size with deposition and retention of inhaled 51Cr-labeled microspheres

    International Nuclear Information System (INIS)

    Hackett, P.L.; Sikov, M.R.; Skiens, W.E.; Cannon, W.C.; Hess, J.O.; Hall, D.

    1980-01-01

    Newborn, juvenile, weanling, and adult rats were exposed to aerosols of 51 Cr-labeled microspheres with AMADs of 0.91, 1.4, 2.3, 3.4, and 4.4 μm. Alveolar deposition was negligible in newborn rats for all particle sizes, and decreased to less than 6% at an AMAD of 2.3 μm in juveniles and weanlings, and an AMAD of 3.4 μm in adults

  10. Deposition of hematite particles on alumina seal faceplates of nuclear reactor coolant pumps: Laboratory experiments and industrial feedback

    OpenAIRE

    Lefèvre, Grégory; Živković, Ljiljana S.; Jaubertie, Anne

    2012-01-01

    In the primary circuit of pressurized water reactors (PWR), the dynamic sealing system in reactor coolant pumps is ensured by mechanical seals whose ceramic parts are in contact with the cooling solution. During the stretch-out phase in reactor operation, characterized by low boric acid concentration, the leak-off flow has been observed to abnormally evolve in industrial plants. The deposition of hematite particles, originating from corrosion, on alumina seals of coolant pumps is suspec...

  11. Deposition kinetics of quantum dots and polystyrene latex nanoparticles onto alumina: role of water chemistry and particle coating.

    Science.gov (United States)

    Quevedo, Ivan R; Olsson, Adam L J; Tufenkji, Nathalie

    2013-03-05

    A clear understanding of the factors controlling the deposition behavior of engineered nanoparticles (ENPs), such as quantum dots (QDs), is necessary for predicting their transport and fate in natural subsurface environments and in water filtration processes. A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the effect of particle surface coatings and water chemistry on the deposition of commercial QDs onto Al2O3. Two carboxylated QDs (CdSe and CdTe) with different surface coatings were compared with two model nanoparticles: sulfate-functionalized (sPL) and carboxyl-modified (cPL) polystyrene latex. Deposition rates were assessed over a range of ionic strengths (IS) in simple electrolyte (KCl) and in electrolyte supplemented with two organic molecules found in natural waters; namely, humic acid and rhamnolipid. The Al2O3 collector used here is selected to be representative of oxide patches found on the surface of aquifer or filter grains. Deposition studies showed that ENP deposition rates on bare Al2O3 generally decreased with increasing salt concentration, with the exception of the polyacrylic-acid (PAA) coated CdTe QD which exhibited unique deposition behavior due to changes in the conformation of the PAA coating. QD deposition rates on bare Al2O3 were approximately 1 order of magnitude lower than those of the polystyrene latex nanoparticles, likely as a result of steric stabilization imparted by the QD surface coatings. Adsorption of humic acid or rhamnolipid on the Al2O3 surface resulted in charge reversal of the collector and subsequent reduction in the deposition rates of all ENPs. Moreover, the ratio of the two QCM-D output parameters, frequency and dissipation, revealed key structural information of the ENP-collector interface; namely, on bare Al2O3, the latex particles were rigidly attached as compared to the more loosely attached QDs. This study emphasizes the importance of considering the nature of ENP coatings as well

  12. Ash transformation in suspension fired boilers co-firing coal and straw

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

    In this literature report is provided a status for the present knowledge level on ash properties when co-firing coal and biomass. The fly ash formed in boilers using co-firing of coal and straw do have a large influence on ash deposit formation, boiler corrosion, fly ash utilization and operation...

  13. Size-dependent photodegradation of CdS particles deposited onto TiO2 mesoporous films by SILAR method

    International Nuclear Information System (INIS)

    Ahmed, Rasin; Will, Geoffrey; Bell, John; Wang Hongxia

    2012-01-01

    The particle size, size distribution and photostability of CdS nanoparticles incorporated onto mesoporous TiO 2 films by a successive ionic layer adsorption and reaction (SILAR) method were investigated by Raman spectroscopy, UV–Visible spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). High-resolution TEM indicated that the synthesized CdS particles were hexagonal phase and the particle sizes were less than 5 nm for up to nine SILAR deposition cycles. Quantum size effect was found with the CdS-sensitized TiO 2 films prepared with up to nine SILAR cycles. The band gap of CdS nanoparticles decreased from 2.65 to 2.37 eV with the increase of the SILAR cycles from 1 to 11. The investigation of the stability of the CdS/TiO 2 films in air under illumination (440.6 μW/cm 2 ) showed that the photodegradation rate was up to 85 % per day for the sample prepared with three SILAR cycles. XPS analysis indicated that the photodegradation was due to the oxidation of CdS, leading to the transformation from sulphide to sulphate (CdSO 4 ). Furthermore, the degradation rate was strongly dependent upon the particle size of CdS. Smaller particles showed faster degradation rate. The size-dependent photo-induced oxidization was rationalized with the variation of size-dependent distribution of surface atoms of CdS particles. Molecular dynamics-based theoretical calculation has indicated that the surface sulphide anion of a large CdS particle such as CdS made with 11 cycles (CdS × 11, average particle size = 5.6 nm) accounts for 9.6 % of the material whereas this value is increased to 19.2 % for (CdS × 3)-based smaller particles (average particle size = 2.7 nm). The photostability of CdS nanoparticles was significantly enhanced when coated with ZnS particles deposited with four SILAR cycles. The growth mechanism of ZnS upon CdS nanoparticles was discussed.

  14. Impinging jet study of the deposition of colloidal particles on synthetic polymer (Zeonor)

    DEFF Research Database (Denmark)

    Vlček, Jakub; Lapčík, Lubomír; Cech, Jiri

    2014-01-01

    In this study, an impinging jet deposition experiments were performed on synthetic polymer (Zeonor) original and by micro-embossing modified substrates with exactly defined topology as confirmed by AFM and SEM. Deposition experiments were performed at ambient temperature and at selected flow regi...

  15. Investigations on chemical-physical conditioning of ashes from the incineration of sewage sludge to deposit on surface landfill site; Untersuchungen zur Chemisch-Physikalischen Behandlung von Klaerschlammverbrennungsasche zur Ablagerung auf oberirdischen Deponien

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, O.; Becker, A. [Technische Univ. Kaiserslautern (Germany). Fachgebiet Bodenmechanik und Grundbau; Scherer, G. [TERRAG Service und Vertrieb GmbH, Homburg (Germany)

    2007-06-15

    Depositing of ashes from the incineration of sewage sludge on landfill is possible after conditioning or within appropriate boxes. The partial high content of chromate- and dichromate- (chrome VI) concentration in the eluate of these slags can cause some difficulties. Presently, disposal of such slags is accomplished in underground spaces. Taking into account the provisions of national laws, possibility is limited. Therefore investigations on deposing of conditioned slags on surface landfills are of growing importance. The binders added to condition the incineration slags were chosen to assess the chemical change of hexavalent chrome (chrome VI) to indissoluble chrome (chrome III). Cement, SAV-residues as well as fly ash were taken as binders. The investigations presented refer to results on mechanical behaviour of conditioned slags. Emphasis is placed on the time-dependent behaviour of strength as well as on water permeability. Several cylindrical samples made by different compounds were tested within a period of about 112 days. Requirements with respect to strength were met within a few days. Demands on the eluate-criteria need additional investigations. (orig.)

  16. Possibilities of utilizing power plant fly ashes

    Directory of Open Access Journals (Sweden)

    Mezencevová Andrea

    2003-09-01

    Full Text Available The burning of fossil fuels in industrial power stations plays a significant role in the production of thermal and electrical energy. Modern thermal power plants are producing large amounts of solid waste, mainly fly ashes. The disposal of power plant waste is a large environmental problem at the present time. In this paper, possibilities of utilization of power plant fly ashes in industry, especially in civil engineering, are presented. The fly ash is a heterogeneous material with various physical, chemical and mineralogical properties, depending on the mineralogical composition of burned coal and on the used combustion technology. The utilization of fly ashes is determined of their properties. The fineness, specific surface area, particle shape, density, hardness, freeze-thaw resistance, etc. are decisive. The building trade is a branch of industry, which employs fly ash in large quantities for several decades.The best utilization of fluid fly ashes is mainly in the production of cement and concrete, due to the excellent pozzolanic and cementitious properties of this waste. In the concrete processing, the fly ash is utilized as a replacement of the fine aggregate (fine filler or a partial replacement for cement (active admixture. In addition to economic and ecological benefits, the use of fly ash in concrete improves its workability and durability, increases compressive and flexural strength, reduces segregation, bleeding, shrinkage, heat evolution and permeability and enhances sulfate resistance of concrete.The aim of current research is to search for new technologies for the fly ash utilization. The very interesting are biotechnological methods to recovery useful components of fly ashes and unconventional methods of modification of fly ash properties such as hydrothermal zeolitization and mechanochemical modification of its properties. Mechanochemistry deals with physico - chemical transformations and chemical reactions of solids induced by

  17. Effects of the addition of oil shale ash and coal ash on physic-chemical properties of CPJ45 cement

    Directory of Open Access Journals (Sweden)

    Nabih K.

    2014-04-01

    Full Text Available We focused our research on recycling industrial wastes, fly ash (F.A, bottom ash (B.A and oil shale ash (S.A in cement production. The study concerns physico-chemical characterization of these products and the influence of their addition on the mechanical proprieties of the CPJ45 cement. XRF allowed us to rank the three additives used according to their contents on major oxides. Coal ashes belong to the class F, and thus possess poozzolanic properties and oil shale ash belongs to the class C and possesses hydraulic and poozolanic properties. The crystalline phases constituting each ash were analysed by XRD. We observe in bottom ash the presence of quartz and mullite. The same crystals are found in fly ash with hematite and magnetite. Oil shale ash is composed of quartz, anhydrite, gehlenite, wollastonite and periclase. The microstructures of fly ash and bottom ash were studied using SEM. The bottom ash was composed respectively of fine particles that are generally irregularly shaped, their dimensions are between 5 and 28μm and of big particles(300 μm. The EDX analysis coupled with an electronic microscope provided some information about the major elements that constitute our samples. The dehydrations of anhydrous and three days hydrated cement were examined by DSC. For hydrated cements we noticed endothermic peaks related to the dehydration of CSH, CH and decomposition of carbonates. The study of the mechanical properties of CPJ45 cement by adding different proportions of fly ash, bottom ash and oil shale ash helped clarifying the percentage of ash that leaded to improve the 28 days mechanical strength. The results show that the cements studied have their maximum mechanical resistance with the addition at 7% of fly ash or 10% of oil shale ash.

  18. Volcanic ash impacts on critical infrastructure

    Science.gov (United States)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.

    2012-01-01

    supply managers include: monitoring turbidity levels in raw water intakes, and if necessary increasing chlorination to compensate for higher turbidity; managing water demand; and communicating monitoring results with the public to allay fears of contamination. Ash can cause major damage to wastewater disposal systems. Ash deposited onto impervious surfaces such as roads and car parks is very easily washed into storm drains, where it can form intractable masses and lead to long-term flooding problems. It can also enter wastewater treatment plants (WWTPs), both through sewer lines and by direct fallout. Damage to modern WWTPs can run into millions of dollars. Ash falls reduce visibility creating hazards for ground transportation. Dry ash is also readily remobilised by vehicle traffic and wind, and dry and wet ash deposits will reduce traction on paved surfaces, including airport runways. Ash cleanup from road and airports is commonly necessary, but the large volumes make it logistically challenging. Vehicles are vulnerable to ash; it will clog filters and brake systems and abrade moving parts within engines. Lastly, modern telecommunications networks appear to be relatively resilient to volcanic ash fall. Signal attenuation and interference during ash falls has not been reported in eruptions over the past 20 years, with the exception of interference from ash plume-generated lightning. However, some telecommunications equipment is vulnerable to airborne ash, in particular heating, ventilation and air-conditioning (HVAC) systems which may become blocked from ash ingestion leading to overheating. This summary of volcanic ash impacts on critical infrastructure provides insight into the relative vulnerability of infrastructure under a range of different ashfall scenarios. Identifying and quantifying these impacts is an essential step in building resilience within these critical systems. We have attempted to consider interdependencies between sectors in a holistic way using

  19. Ash transformation during co-firing coal and straw

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

    2007-01-01

    Co-firing straw with coal in pulverized fuel boilers can cause problems related to fly ash utilization, deposit formation, corrosion and SCR catalyst deactivation due to the high contents of Cl and K in the ash. To investigate the interaction between coal and straw ash and the effect of coal...... quality on fly ash and deposit properties, straw was co-fired with three kinds of coal in an entrained flow reactor. The compositions of the produced ashes were compared to the available literature data to find suitable scaling parameters that can be used to predict the composition of ash from straw...... and coal co-firing. Reasonable agreement in fly ash compositions regarding total K and fraction of water soluble K was obtained between co-firing in an entrained flow reactor and full-scale plants. Capture of potassium and subsequent release of HCl can be achieved by sulphation with SO2 and more...

  20. Role of particle size and composition in metal adsorption by solids deposited on urban road surfaces

    International Nuclear Information System (INIS)

    Gunawardana, Chandima; Egodawatta, Prasanna; Goonetilleke, Ashantha

    2014-01-01

    Despite common knowledge that the metal content adsorbed by fine particles is relatively higher compared to coarser particles, the reasons for this phenomenon have gained little research attention. The research study discussed in the paper investigated the variations in metal content for different particle sizes of solids associated with pollutant build-up on urban road surfaces. Data analysis confirmed that parameters favourable for metal adsorption to solids such as specific surface area, organic carbon content, effective cation exchange capacity and clay forming minerals content decrease with the increase in particle size. Furthermore, the mineralogical composition of solids was found to be the governing factor influencing the specific surface area and effective cation exchange capacity. There is high quartz content in particles >150 μm compared to particles <150 μm. As particle size reduces below 150 μm, the clay forming minerals content increases, providing favourable physical and chemical properties that influence adsorption. -- Highlights: • Physico-chemical parameters investigated in build-up samples from 32 road surfaces. • Mineralogical composition primarily governs the physico-chemical characteristics. • High clay forming mineral content in fine solids increases SSA and ECEC. • Characteristics influenced by quartz and amorphous content with particle size. • High quartz content in coarse particles contributes reduced metal adsorption. -- The mineralogical composition of solids is the governing factor influencing metal adsorption to solids in pollutant build-up on urban surfaces

  1. An improved design of TRISO particle with porous SiC inner layer by fluidized bed-chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rongzheng; Liu, Malin, E-mail: liumalin@tsinghua.edu.cn; Chang, Jiaxing; Shao, Youlin; Liu, Bing

    2015-12-15

    Tristructural-isotropic (TRISO) particle has been successful in high temperature gas cooled reactor (HTGR), but an improved design is required for future development. In this paper, the coating layers are reconsidered, and an improved design of TRISO particle with porous SiC inner layer is proposed. Three methods of preparing the porous SiC layer, called high methyltrichlorosilane (MTS) concentration method, high Ar concentration method and hexamethyldisilane (HMDS) method, are experimentally studied. It is indicated that porous SiC layer can be successfully prepared and the density of SiC layer can be adjusted by tuning the preparation parameters. Microstructure and characterization of the improved TRISO coated particle are given based on scanning electron microscope (SEM), X-ray diffraction (XRD), Raman scattering and energy dispersive X-ray (EDX) analysis. It can be found that the improved TRISO coated particle with porous SiC layer can be mass produced successfully. The formation mechanisms of porous SiC layer are also discussed based on the fluidized bed-chemical vapor deposition principle. - Graphical abstract: An improved design of TRISO particle with porous SiC inner layer to replace the inner porous pyrolytic carbon layer was proposed and prepared by FB-CVD method. This new design is aimed to reduce the total internal pressure of the particles by reducing the formation of CO and to reduce the risks of amoeba effect. - Highlights: • An improved design of TRISO particle with porous SiC inner layer was proposed. • Three methods of preparing porous SiC layer are proposed and experimentally studied. • The density of porous SiC layer can be controlled by adjusting experimental parameters. • Formation mechanisms of porous SiC layer were given based on the FB-CVD principle. • TRISO particles with porous SiC inner layer were mass produced successfully.

  2. Spacer geometry and particle deposition in spiral wound membrane feed channels

    KAUST Repository

    Radu, A.I.; van Steen, M.S.H.; Vrouwenvelder, Johannes S.; van Loosdrecht, Mark C.M.; Picioreanu, C.

    2014-01-01

    Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nanofiltration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic

  3. Biological Effects of Particles with Very High Energy Deposition on Mammalian Cells Utilizing the Brookhaven Tandem Van de Graaff Accelerator

    Science.gov (United States)

    Saha, Janapriya; Cucinotta, Francis A.; Wang, Minli

    2013-01-01

    High LET radiation from GCR (Galactic Cosmic Rays) consisting mainly of high charge and energy (HZE) nuclei and secondary protons and neutrons, and secondaries from protons in SPE (Solar Particle Event) pose a major health risk to astronauts due to induction of DNA damage and oxidative stress. Experiments with high energy particles mimicking the space environment for estimation of radiation risk are being performed at NASA Space Radiation Laboratory at BNL. Experiments with low energy particles comparing to high energy particles of similar LET are of interest for investigation of the role of track structure on biological effects. For this purpose, we report results utilizing the Tandem Van de Graaff accelerator at BNL. The primary objective of our studies is to elucidate the influence of high vs low energy deposition on track structure, delta ray contribution and resulting biological responses. These low energy ions are of special relevance as these energies may occur following absorption through the spacecraft and shielding materials in human tissues and nuclear fragments produced in tissues by high energy protons and neutrons. This study will help to verify the efficiency of these low energy particles and better understand how various cell types respond to them.

  4. Effect of enzyme-induced pulmonary emphysema in Syrian hamsters on the deposition and retention of inhaled particles

    International Nuclear Information System (INIS)

    Hahn, F.F.; Hobbs, C.H.

    1974-01-01

    Experimental emphysema was induced in Syrian hamsters by intratracheal injection of elastase or by inhaled papain aerosols. Control hamsters were injected with saline or exposed to enzyme diluent aerosols. After 3 weeks, all groups were simultaneously exposed to an aerosol of relatively insoluble 137 Cs in fused clay particles with an activity median aerodynamic diameter of 1.4 to 1.6 and a geometric standard deviation of 1.6. The initial pulmonary deposition of particles (measured 3 hours after inhalation) was significantly lower in treated hamsters, 45 percent of controls with elastase and 65 percent with papain aerosols. The effect of both enzyme treatments on the retention of particles was similar in spite of the fact that the pulmonary lesions were not the same. Elastase I.T. caused a diffuse destruction and enlargement of alveoli with a loss of pulmonary elastic recoil. Papain aerosols caused a focal destruction and enlargement of alveoli with no loss of elastic recoil. The common feature of both lesions was an increased number of alveolar macrophages which may account for the early increased clearance of particles. The prolonged retention of particles may be due to focal accumulations of macrophages in distal alveoli. (U.S.)

  5. Effects of nasal drug delivery device and its orientation on sprayed particle deposition in a realistic human nasal cavity.

    Science.gov (United States)

    Tong, Xuwen; Dong, Jingliang; Shang, Yidan; Inthavong, Kiao; Tu, Jiyuan

    2016-10-01

    In this study, the effects of nasal drug delivery device and the spray nozzle orientation on sprayed droplets deposition in a realistic human nasal cavity were numerically studied. Prior to performing the numerical investigation, an in-house designed automated actuation system representing mean adults actuation force was developed to produce realistic spray plume. Then, the spray plume development was filmed by high speed photography system, and spray characteristics such as spray cone angle, break-up length, and average droplet velocity were obtained through off-line image analysis. Continuing studies utilizing those experimental data as boundary conditions were applied in the following numerical spray simulations using a commercially available nasal spray device, which was inserted into a realistic adult nasal passage with external facial features. Through varying the particle releasing direction, the deposition fractions of selected particle sizes on the main nasal passage for targeted drug delivery were compared. The results demonstrated that the middle spray direction showed superior spray efficiency compared with upper or lower directions, and the 10µm agents were the most suitable particle size as the majority of sprayed agents can be delivered to the targeted area, the main passage. This study elaborates a comprehensive approach to better understand nasal spray mechanism and evaluate its performance for existing nasal delivery practices. Results of this study can assist the pharmaceutical industry to improve the current design of nasal drug delivery device and ultimately benefit more patients through optimized medications delivery. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Utilization of Hospital Waste Ash in Concrete

    Directory of Open Access Journals (Sweden)

    Shazim Ali Memon

    2013-01-01

    Full Text Available Hospital waste management is a huge problem in Pakistan. The annual production of medical waste produced from health care facilities, in Pakistan, is around 250,000 tons. This research paper is intended to evaluate the feasibility of using of hospital waste ash obtained from Pakistan Institute of Medical Sciences, Rawalpindi, Pakistan, as partial replacement of cement. The main variable in this research is the amount of hospital waste ash (2, 4, 6 and 8% by weight of cement while the amount of cementitious material, water to cementitious material ratio, fine and coarse aggregate content were kept constant. Test results substantiate that hospital waste ash can be used in concrete. XRD (X-Ray Diffraction of hospital waste ash showed that it is rich in calcite while scanning electron micrographs indicated that the particles of hospital waste ash have highly irregular shape. The slump value, density of fresh concrete and water absorption decreased with the increase in the quantity of hospital waste ash in the mix. At 3 days of testing, the compressive strength of mixes with hospital waste ash was higher than the control mix while at 7 and 28 days the CM (Control Mix showed higher strength than the hospital waste ash mixes except the mix containing 2% hospital waste ash by weight of cement.

  7. Utilization of hospital waste ash in concrete

    International Nuclear Information System (INIS)

    Memon, S.; Sheikh, M.

    2013-01-01

    Hospital waste management is a huge problem in Pakistan. The annual production of medical waste produced from health care facilities, in Pakistan, is around 250,000 tons. This research paper is intended to evaluate the feasibility of using of hospital waste ash obtained from Pakistan Institute of Medical Sciences, Rawalpindi, Pakistan, as partial replacement of cement. The main variable in this research is the amount of hospital waste ash (2, 4, 6 and 8% by weight of cement) while the amount of cementitious material, water to cementitious material ratio, fine and coarse aggregate content were kept constant. Test results substantiate that hospital waste ash can be used in concrete. XRD (X-Ray Diffraction) of hospital waste ash showed that it is rich in calcite while scanning electron micrographs indicated that the particles of hospital waste ash have highly irregular shape. The slump value, density of fresh concrete and water absorption decreased with the increase in the quantity of hospital waste ash in the mix. At 3 days of testing, the compressive strength of mixes with hospital waste ash was higher than the control mix while at 7 and 28 days the CM (Control Mix) showed higher strength than the hospital waste ash mixes except the mix containing 2% hospital waste ash by weight of cement. (author)

  8. Surface modification of 2014 aluminium alloy-Al2O3 particles composites by nickel electrochemical deposition

    International Nuclear Information System (INIS)

    Molina, J.M.; Saravanan, R.A.; Narciso, J.; Louis, E.

    2004-01-01

    A method to modify the surface of aluminium matrix composites (AMC) by electrochemical nickel deposition has been developed. Deposition was carried out in a stirred standard Watt's bath, whereas potential and time were varied to optimize coating characteristics. The method, that allowed to overcome the serious difficulties associated to electrochemical deposition of an inherently inhomogeneous material, was used to nickel coat composites of 2014 aluminium alloy-15 vol.% Al 2 O 3 particles. Coats with a good adherence and up to 60 μm thick were easily obtained. In order to improve surface properties, the coated composite was subjected to rather long (from 10 to 47.5 h) heat treatments at a temperature of 520 deg,C. The heat treatments improved the uniformity of the deposited layer and promoted the formation of Al-Ni intermetallics (mainly Al 3 Ni 2 , as revealed by X-ray diffraction and energy-dispersive X-ray analysis (EDX)). Experimental results indicate that growth of the intermetallic layer is diffusion limited

  9. Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project.

    Science.gov (United States)

    Bednar, A J; Averett, D E; Seiter, J M; Lafferty, B; Jones, W T; Hayes, C A; Chappell, M A; Clarke, J U; Steevens, J A

    2013-09-01

    A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river. Published by Elsevier Ltd.

  10. Comparisons of calculated respiratory tract deposition of particles based on the NCRP/ITRI model and the new ICRP66 model

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Hsu-Chi; Phalen, R.F. [Univ. of California, Irvine, CA (United States); Chang, I. [Lovelace Inst., Albuquerque, NM (United States)] [and others

    1995-12-01

    The National Council on Radiation Protection and Measurements (NCRP) in the United States and the International Commission on Radiological Protection (ICRP) have been independently reviewing and revising respiratory tract dosimetry models for inhaled radioactive aerosols. The newly proposed NCRP respiratory tract dosimetry model represents a significant change in philosophy from the old ICRP Task Group model. The proposed NCRP model describes respiratory tract deposition, clearance, and dosimetry for radioactive substances inhaled by workers and the general public and is expected to be published soon. In support of the NCRP proposed model, ITRI staff members have been developing computer software. Although this software is still incomplete, the deposition portion has been completed and can be used to calculate inhaled particle deposition within the respiratory tract for particle sizes as small as radon and radon progeny ({approximately} 1 nm) to particles larger than 100 {mu}m. Recently, ICRP published their new dosimetric model for the respiratory tract, ICRP66. Based on ICRP66, the National Radiological Protection Board of the UK developed PC-based software, LUDEP, for calculating particle deposition and internal doses. The purpose of this report is to compare the calculated respiratory tract deposition of particles using the NCRP/ITRI model and the ICRP66 model, under the same particle size distribution and breathing conditions. In summary, the general trends of the deposition curves for the two models were similar.