Influence of coal slurry particle composition on pipeline hydraulic transportation behavior

Science.gov (United States)

Li-an, Zhao; Ronghuan, Cai; Tieli, Wang

2018-02-01

Acting as a new type of energy transportation mode, the coal pipeline hydraulic transmission can reduce the energy transportation cost and the fly ash pollution of the conventional coal transportation. In this study, the effect of average velocity, particle size and pumping time on particle composition of coal particles during hydraulic conveying was investigated by ring tube test. Meanwhile, the effects of particle composition change on slurry viscosity, transmission resistance and critical sedimentation velocity were studied based on the experimental data. The experimental and theoretical analysis indicate that the alter of slurry particle composition can lead to the change of viscosity, resistance and critical velocity of slurry. Moreover, based on the previous studies, the critical velocity calculation model of coal slurry is proposed.

Size Effect on Acoustic Emission Characteristics of Coal-Rock Damage Evolution

Directory of Open Access Journals (Sweden)

Zhijie Wen

2017-01-01

Full Text Available Coal-gas outburst, rock burst, and other mine dynamic disasters are closely related to the instability and failure of coal-rock. Coal-rock is the assemblies of mineral particles of varying sizes and shapes bonded together by cementing materials. The damage and rupture process of coal-rock is accompanied by acoustic emission (AE, which can be used as an effective means to monitor and predict the instability of coal-rock body. In this manuscript, considering the size effect of coal-rock, the influence of different height to diameter ratio on the acoustic emission characteristics of coal-rock damage evolution was discussed by microparticle flow PFC2D software platform. The results show that coal-rock size influences the uniaxial compressive strength, peak strain, and elastic modulus of itself; the size effect has little effect on the acoustic emission law of coal-rock damage and the effects of the size of coal-rock samples on acoustic emission characteristics are mainly reflected in three aspects: the triggering time of acoustic emission, the strain range of strong acoustic emission, and the intensity of acoustic emission; the damage evolution of coal-rock specimen can be divided into 4 stages: initial damage, stable development, accelerated development, and damage.

Volatile release and particle formation characteristics of injected pulverized coal in blast furnaces

International Nuclear Information System (INIS)

Chen, Wei-Hsin; Du, Shan-Wen; Yang, Tsung-Han

2007-01-01

Volatiles release and particle formation for two kinds of pulverized coals (a high volatile bituminous coal and a low volatile bituminous coal) in a drop tube furnace are investigated to account for the reactions of pulverized coal injected in blast furnaces. Two different sizes of feed particles are considered; one is 100-200 mesh and the other is 200-325 mesh. By evaluating the R-factor, the devolatilization extent of the larger feed particles is found to be relatively poor. However, the swelling behavior of individual or two agglomerated particles is pronounced, which is conducive to gasification of the chars in blast furnaces. In contrast, for the smaller feed particles, volatiles liberated from the coal particles can be improved in a significant way as a result of the amplified R-factor. This enhancement can facilitate the performance of gas phase combustion. Nevertheless, the residual char particles are characterized by agglomeration, implying that the reaction time of the char particles will be lengthened, thereby increasing the possibility of furnace instability. Double peak distributions in char particle size are observed in some cases. This possibly results from the interaction of the plastic state and the blowing effect at the particle surface. Considering the generation of tiny aerosols composed of soot particles and tar droplets, the results indicate that their production is highly sensitive to the volatile matter and elemental oxygen contained in the coal. Comparing the reactivity of the soot to that of the unburned char, the former is always lower than the latter. Consequently, the lower is the soot formation, the better is the blast furnace stability

Particle size distribution instrument. Topical report 13

Energy Technology Data Exchange (ETDEWEB)

Okhuysen, W.; Gassaway, J.D.

1995-04-01

The development of an instrument to measure the concentration of particles in gas is described in this report. An in situ instrument was designed and constructed which sizes individual particles and counts the number of occurrences for several size classes. Although this instrument was designed to detect the size distribution of slag and seed particles generated at an experimental coal-fired magnetohydrodynamic power facility, it can be used as a nonintrusive diagnostic tool for other hostile industrial processes involving the formation and growth of particulates. Two of the techniques developed are extensions of the widely used crossed beam velocimeter, providing simultaneous measurement of the size distribution and velocity of articles.

Coal emissions adverse human health effects associated with ultrafine/nano-particles role and resultant engineering controls.

Science.gov (United States)

Oliveira, Marcos L S; Navarro, Orlando G; Crissien, Tito J; Tutikian, Bernardo F; da Boit, Kátia; Teixeira, Elba C; Cabello, Juan J; Agudelo-Castañeda, Dayana M; Silva, Luis F O

2017-10-01

There are multiple elements which enable coal geochemistry: (1) boiler and pollution control system design parameters, (2) temperature of flue gas at collection point, (3) feed coal and also other fuels like petroleum coke, tires and biomass geochemistry and (4) fuel feed particle size distribution homogeneity distribution, maintenance of pulverisers, etc. Even though there is a large number of hazardous element pollutants in the coal-processing industry, investigations on micrometer and nanometer-sized particles including their aqueous colloids formation reactions and their behaviour entering the environment are relatively few in numbers. X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/ (Energy Dispersive Spectroscopy) EDS/ (selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis were used as an integrated characterization techniques tool box to determine both geochemistry and nanomineralogy for coal fly ashes (CFAs) from Brazil´s largest coal power plant. Ultrafine/nano-particles size distribution from coal combustion emissions was estimated during the tests. In addition the iron and silicon content was determined as 54.6% of the total 390 different particles observed by electron bean, results aimed that these two particles represent major minerals in the environment particles normally. These data may help in future investigations to asses human health actions related with nano-particles. Copyright © 2017 Elsevier Inc. All rights reserved.

Novel fragmentation model for pulverized coal particles gasification in low temperature air thermal plasma

Directory of Open Access Journals (Sweden)

Jovanović Rastko D.

2016-01-01

Full Text Available New system for start-up and flame support based on coal gasification by low temperature air thermal plasma is planned to supplement current heavy oil system in Serbian thermal power plants in order to decrease air pollutions emission and operational costs. Locally introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. Important stages during particle combustion, such as particle devolatilisation and char combustion, are described with satisfying accuracy in existing commercial CFD codes that are extensively used as powerful tool for pulverized coal combustion and gasification modeling. However, during plasma coal gasification, high plasma temperature induces strong thermal stresses inside interacting coal particles. These stresses lead to “thermal shock” and extensive particle fragmentation during which coal particles with initial size of 50-100 m disintegrate into fragments of at most 5-10 m. This intensifies volatile release by a factor 3-4 and substantially accelerates the oxidation of combustible matter. Particle fragmentation, due to its small size and thus limited influence on combustion process is commonly neglected in modelling. The main focus of this work is to suggest novel approach to pulverized coal gasification under high temperature conditions and to implement it into commercial comprehensive code ANSYS FLUENT 14.0. Proposed model was validated against experimental data obtained in newly built pilot scale D.C plasma burner test facility. Newly developed model showed very good agreement with experimental results with relative error less than 10%, while the standard built-in gasification model had error up to 25%.

Mass spectra features of biomass burning boiler and coal burning boiler emitted particles by single particle aerosol mass spectrometer.

Science.gov (United States)

Xu, Jiao; Li, Mei; Shi, Guoliang; Wang, Haiting; Ma, Xian; Wu, Jianhui; Shi, Xurong; Feng, Yinchang

2017-11-15

In this study, single particle mass spectra signatures of both coal burning boiler and biomass burning boiler emitted particles were studied. Particle samples were suspended in clean Resuspension Chamber, and analyzed by ELPI and SPAMS simultaneously. The size distribution of BBB (biomass burning boiler sample) and CBB (coal burning boiler sample) are different, as BBB peaks at smaller size, and CBB peaks at larger size. Mass spectra signatures of two samples were studied by analyzing the average mass spectrum of each particle cluster extracted by ART-2a in different size ranges. In conclusion, BBB sample mostly consists of OC and EC containing particles, and a small fraction of K-rich particles in the size range of 0.2-0.5μm. In 0.5-1.0μm, BBB sample consists of EC, OC, K-rich and Al_Silicate containing particles; CBB sample consists of EC, ECOC containing particles, while Al_Silicate (including Al_Ca_Ti_Silicate, Al_Ti_Silicate, Al_Silicate) containing particles got higher fractions as size increase. The similarity of single particle mass spectrum signatures between two samples were studied by analyzing the dot product, results indicated that part of the single particle mass spectra of two samples in the same size range are similar, which bring challenge to the future source apportionment activity by using single particle aerosol mass spectrometer. Results of this study will provide physicochemical information of important sources which contribute to particle pollution, and will support source apportionment activities. Copyright © 2017. Published by Elsevier B.V.

Single particle aerosol mass spectrometry of coal combustion particles associated with high lung cancer rates in Xuanwei and Fuyuan, China.

Science.gov (United States)

Lu, Senlin; Tan, Zhengying; Liu, Pinwei; Zhao, Hui; Liu, Dingyu; Yu, Shang; Cheng, Ping; Win, Myat Sandar; Hu, Jiwen; Tian, Linwei; Wu, Minghong; Yonemochi, Shinich; Wang, Qingyue

2017-11-01

Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM). The total of 38,372 particles mass-analyzed by SPAMS can be divided into 9 groups based on their chemical composition and their number percentages: carbonaceous, Na-rich, K-rich, Al-rich, Fe-rich, Si-rich, Ca-rich, heavy metal-bearing, and PAH-bearing particles. The carbonaceous and PAH-bearing particles are enriched in the size range below 0.56 μm, Fe-bearing particles range from 0.56 to 1.0 μm in size, and heavy metals such as Ti, V, Cr, Cu, Zn, and Pb have diameters below 1 μm. The TEM results show that the particles from Xuanwei and Fuyuan coal combustion can be classified into soot aggregates, Fe-rich particles, heavy metal containing particles, and mineral particles. Non-volatile particles detected by SPAMS could also be observed with TEM. The number percentages by SPAMS also correlate with the mass concentrations measured by ICP-MS. Our results could provide valuable insight for understanding high lung cancer incidence in the area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nanometre-sized pores in coal: Variations between coal basins and coal origin

Science.gov (United States)

Sakurovs, Richard; Koval, Lukas; Grigore, Mihaela; Sokolava, Anna; Ruppert, Leslie F.; Melnichenko, Yuri B.

2018-01-01

We have used small angle neutron scattering (SANS) to investigate the differences in methane and hexane penetration in pores in bituminous coal samples from the U.S., Canada, South Africa, and China, and maceral concentrates from Australian coals. This work is an extension of previous work that showed consistent differences between the extent of penetration by methane into 10–20 nm size pores in inertinite in bituminous coals from Australia, North America and Poland.In this study we have confirmed that there are differences in the response of inertinite to methane and hexane penetration in coals sourced from different coal basins. Inertinite in Permian Australian coals generally has relatively high numbers of pores in the 2.5–250 nm size range and the pores are highly penetrable by methane and hexane; coals sourced from Western Canada had similar penetrability to these Australian coals. However, the penetrability of methane and hexane into inertinite from the Australian Illawarra Coal Measures (also Permian) is substantially less than that of the other Australian coals; there are about 80% fewer 12 nm pores in Illawarra inertinite compared to the other Australian coals examined. The inertinite in coals sourced from South Africa and China had accessibility intermediate between the Illawarra coals and the other Australian coals.The extent of hexane penetration was 10–20% less than CD4 penetration into the same coal and this difference was most pronounced in the 5–50 nm pore size range. Hexane and methane penetrability into the coals showed similar trends with inertinite content.The observed variations in inertinite porosity between coals from different coal regions and coal basins may explain why previous studies differ in their observations of the relationships between gas sorption behavior, permeability, porosity, and maceral composition. These variations are not simply a demarcation between Northern and Southern Hemisphere coals.

Atmospheric particulate matter size distribution and concentration in West Virginia coal mining and non-mining areas.

Science.gov (United States)

Kurth, Laura M; McCawley, Michael; Hendryx, Michael; Lusk, Stephanie

2014-07-01

People who live in Appalachian areas where coal mining is prominent have increased health problems compared with people in non-mining areas of Appalachia. Coal mines and related mining activities result in the production of atmospheric particulate matter (PM) that is associated with human health effects. There is a gap in research regarding particle size concentration and distribution to determine respiratory dose around coal mining and non-mining areas. Mass- and number-based size distributions were determined with an Aerodynamic Particle Size and Scanning Mobility Particle Sizer to calculate lung deposition around mining and non-mining areas of West Virginia. Particle number concentrations and deposited lung dose were significantly greater around mining areas compared with non-mining areas, demonstrating elevated risks to humans. The greater dose was correlated with elevated disease rates in the West Virginia mining areas. Number concentrations in the mining areas were comparable to a previously documented urban area where number concentration was associated with respiratory and cardiovascular disease.

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

Experimental Investigation into the Combustion Characteristics on the Co-firing of Biomass with Coal as a Function of Particle Size and Blending Ratio

Energy Technology Data Exchange (ETDEWEB)

Lkhagvadorj, Sh; Kim, Sang In; Lim, Ho; Kim, Seung Mo; Jeon, Chung Hwan [Pusan National Univ., Busan (Korea, Republic of); Lee, Byoung Hwa [Doosan Heavy Industries and Construction, Ltd., Changwon (Korea, Republic of)

2016-01-15

Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.

The application of the coal grain analysis method to coal liberation studies

Energy Technology Data Exchange (ETDEWEB)

O' Brien, G.; Firth, B.; Adair, B. [CSIRO Earth Science & Resource Engineering Brisbane, Qld. (Australia)

2011-07-01

Emerging coal markets such as the use of coal for conversion to liquid fuels and its use in fuels cells and as coal water slurries in diesel engines require coal products with different coal quality specifications than those applicable to traditional coal markets of coke making and conventional power generation. As well as quantifying coals in terms of their chemical and physical properties, detailed knowledge of the mineral inclusions within the coal particles is required to identify coals that are suited to economically produce the low-ash value coals required for these markets. After mining and processing, some particles can consist of essentially pure components of a single maceral or mineral phase whilst others are composite particles that are comprised of varying amounts of macerals and minerals. The proportion of particles that are present as pure components or as composites will be a function of the characteristics of the coal and the particle size. In general, it is considered that size reduction will result in liberation and hence increased yield. The amount of liberation that occurs during crushing or grinding a coal is however coal specific. Particle characterization information provided by an optical microscopic-imaging method, Coal Grain Analysis, was used to identify coals that might benefit from additional crushing to improve recovery of clean coal by new density separation techniques and by flotation. As expected, the results of these studies suggest that the degree of liberation that is obtained is coal specific, and, hence, yield improvements are also coal specific. Hence a quantitative method of investigating this issue is required.

Source apportionment of aerosol particles at a European air pollution hot spot using particle number size distributions and chemical composition.

Science.gov (United States)

Leoni, Cecilia; Pokorná, Petra; Hovorka, Jan; Masiol, Mauro; Topinka, Jan; Zhao, Yongjing; Křůmal, Kamil; Cliff, Steven; Mikuška, Pavel; Hopke, Philip K

2018-03-01

Ostrava in the Moravian-Silesian region (Czech Republic) is a European air pollution hot spot for airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and ultrafine particles (UFPs). Air pollution source apportionment is essential for implementation of successful abatement strategies. UFPs or nanoparticles of diameter hot-spot including nanoparticles, Positive Matrix Factorization (PMF) was applied to highly time resolved particle number size distributions (NSD, 14 nm-10 μm) and PM 0.09-1.15 chemical composition. Diurnal patterns, meteorological variables, gaseous pollutants, organic markers, and associations between the NSD factors and chemical composition factors were used to identify the pollution sources. The PMF on the NSD reveals two factors in the ultrafine size range: industrial UFPs (28%, number mode diameter - NMD 45 nm), industrial/fresh road traffic nanoparticles (26%, NMD 26 nm); three factors in the accumulation size range: urban background (24%, NMD 93 nm), coal burning (14%, volume mode diameter - VMD 0.5 μm), regional pollution (3%, VMD 0.8 μm) and one factor in the coarse size range: industrial coarse particles/road dust (2%, VMD 5 μm). The PMF analysis of PM 0.09-1.15 revealed four factors: SIA/CC/BB (52%), road dust (18%), sinter/steel (16%), iron production (16%). The factors in the ultrafine size range resolved with NSD have a positive correlation with sinter/steel production and iron production factors resolved with chemical composition. Coal combustion factor resolved with NSD has moderate correlation with SIA/CC/BB factor. The organic markers homohopanes correlate with coal combustion and the levoglucosan correlates with urban background. The PMF applications to NSD and chemical composition datasets are complementary. PAHs in PM 1 were found to be associated with coal combustion factor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fine particles flotation of the Moatize coal/Mozambique

Science.gov (United States)

Castro, Amilton; de Brum, Irineu A. S.

2017-11-01

This study was done from a sample of coal mined at the Vale-Mozambique mine, located in Moatize district, Tete Province. The aim of this work is to analyze the reagent system in the flotation of coal fines belonging to the UCB layer. Among coal processing methods, flotation stands out as one of the most important for the concentration of this material, in particular in the treatment of fine particles. The total feed of the Vale-Mozambique processing plant is 8000 tph of coal, where 10% of this feed corresponds to the fine fraction that feeds the flotation circuit. The material used in this study had a particle size of 96% smaller than 0.25 mm. The reagents used in the flotation tests were Betacol and diesel oil as hydrophobizing agents and MIBC as frother. The range of Betacol concentrations in the first test phase was 200 g / t at 500 g / t, and in the second phase 200 g / t at 500 g / t of diesel oil and MIBC were kept constant at 300 g / t. The immediate analysis followed the Brazilian standards: NBR 8289, NBR 8293, NBR 8290, NBR 8299. The results showed that it is possible, from a feed with the ash content around 22.84%, to obtain products with levels below of 10% ash, with a mass recovery around 50%. The recovery of carbonaceous matter was also evaluated and presented positive results. Complementing this study, the effect of H2O recovery was evaluated and it was observed that for the concentrations of Betacol the recoveries ranged from 6 to 9%, and for diesel oil plus MIBC were 4 to 7%.

Dewatering behaviour of ultrafine hard coal particles

Energy Technology Data Exchange (ETDEWEB)

Fischer, D.; Alizadeh, A.; Simonis, W.

1986-03-01

With decreasing particle diameter distribution the dewatering behaviour of coal gets increasingly complicated. A correlation between final moisture and content of particles below 25..mu..m in the course of centrifuging can be verified. This behaviour of the particles below 25..mu..m can be explained by the great specific surface, on the one hand, and by the distribution of the surface charge density, on the other hand. The charge density depends on the type of coal, on the minerals content and their make-up, as well as on the characteristics of the surrounding medium. The surface charge can be measured indirectly. Varying electrophoretic mobilities of the particles are observed in dependence on the type of raw material. In the neutral pH-range, minerals have a negative surface charge, while coal has a positive one. By way of adding reagents it is possible to invert the negative charges with complicated dewatering characteristics into positive charges. A similar influence will be exerted by changing the pH-value. 6 references.

The effect of particle size of comminuted bituminous coal on low-temperature sorption of nitrogen and room-temperature sorption of carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Cygankiewicz, J.; Dudzinska, A.; Zyla, M.

2006-11-15

Sorption isotherms of N2 and CO{sub 2} were determined at 77.5 and 293 K, respectively, on 65-85% C bituminous coals (type 32) in relation to particle size (0.063-0.075, 0.075-0.125, 0.1250.25, and 0.25-0.355 mm), volatiles, and origin. N2 sorbed only on the external surface, at best on the 0.063-0.075 mm grade (1.18-3.53 m{sup 2}/g in specific surface). CO{sub 2} penetrated very easily into the micro and submicro porous structure (so that it could displace other gases, e.g. CH4 and thus enabled the micropore volume and the specific surface of the coals to be determined. The porous structure was as accessible to CO{sub 2} as it was to H{sub 2}O and MeOH.

Picobubble enhanced fine coal flotation

Energy Technology Data Exchange (ETDEWEB)

Tao, Y.J.; Liu, J.T.; Yu, S.; Tao, D. [University of Kentucky, Lexington, KY (United States). Dept. of Mining Engineering

2006-07-01

Froth flotation is widely used in the coal industry to clean -28 mesh fine coal. A successful recovery of particles by flotation depends on efficient particle-bubble collision and attachment with minimal subsequent particle detachment from bubble. Flotation is effective in a narrow size range beyond which the flotation efficiency drops drastically. It is now known that the low flotation recovery of particles in the finest size fractions is mainly due to a low probability of bubble-particle collision while the main reason for poor coarse particle flotation recovery is the high probability of detachment. A fundamental analysis has shown that use of picobubbles can significantly improve the flotation recovery of particles in a wide range of size by increasing the probability of collision and attachment and reducing the probability of detachment. A specially designed column with a picobubble generator has been developed for enhanced recovery of fine coal particles. Picobubbles were produced based on the hydrodynamic cavitation principle. They are characterized by a size distribution that is mostly below 1 {mu}m and adhere preferentially to the hydrophobic surfaces. The presence of picobubbles increases the probability of collision and attachment and decreases the probability of detachment, thus enhancing flotation recovery. Experimental results with the Coalberg seam coal in West Virginia, U.S.A. have shown that the use of picobubbles in a 2 in. column flotation increased fine coal recovery by 10-30%, depending on the feed rate, collector dosage, and other flotation conditions. Picobubbles also acted as a secondary collector and reduced the collector dosage by one third to one half.

Energy characteristics of finest coal particles surfaces versus their upgrading using flotation

Energy Technology Data Exchange (ETDEWEB)

Jerzy Sablik

2007-07-01

The paper presents selected results of investigations on energy properties of the fine coal particles, and methodological grounds for conducting such investigations. Using the discussed relationships, values of contact angle of coal particles with various degree of coalification in the range defined by the energy nonhomogeneity of the surfaces were computed. There have been determined the values of the contact angles of coal particles with hydrophobic and hydrophilic surfaces after coating with nonpolar and polar reagents. The energy state of the surfaces of coal particles in the feeds and products of industrial flotation were determined, which enabled to evaluate this process. 22 refs., 6 figs., 4 tabs.

Effect of coal stress on grain size of the gotten

Energy Technology Data Exchange (ETDEWEB)

Sikora, W; Tront, A

1988-09-01

Presents investigation results on the effect of seam stress and strain state on winning as measured by the grain size of the gotten. The investigations were carried out at the Institute of Mining Mechanization of the Silesian Politechnical where the relations between parameters of seams and cutters and their effect on coal grain size and energy consumption have been studied for several years. The effect was examined on coal samples taken from 4 mines in the Upper Silesian coal basin using a model of the system: seam - cutter. Cubic samples (400x400x400 mm) were tested on the CMG KOMAG test stand equipped with the POS-1 cutting apparatus. Two types of coal were distinguished: that particularly sensitive to increased pressure on seam and that only negligibly susceptible. Corresponding graphs of coal grain size versus vertical pressure are shown. A function has been developed that characterizes this sensitivity depending on a material parameter that can be determined by workability tests. The relationship between coal strength and grain size yield greater than 10 mm in the gotten depending on dynamic crushability of coal is shown in graphs. 6 refs.

Formation of fine particles in co-combustion of coal and solid recovered fuel in a pulverized coal-fired power station

DEFF Research Database (Denmark)

Wu, Hao; Pedersen, Anne Juul; Glarborg, Peter

2011-01-01

showed an ultrafine mode centered at approximately 0.1 μm. Compared with coal combustion, co-combustion of coal and SRF increased the formation of submicron particles, especially ultrafine particles below 0.2 μm. The morphology of the particles indicated that supermicron particles were primarily formed...... by the melting of minerals. The ultrafine particles were generated through nucleation and coagulation of vaporized inorganic species, while for the particles in between supermicron and ultrafine particles, condensation of vaporized species or aggregation of nucleates on the existing spherical submicron particles...... appear to be an important formation mechanism. The elemental composition of the particles from coal combustion showed that S and Ca were significantly enriched in ultrafine particles and P was also enriched considerably. However, compared with supermicron particles, the contents of Al, Si and K were...

Optimization of laser-induced breakdown spectroscopy for coal powder analysis with different particle flow diameters

Energy Technology Data Exchange (ETDEWEB)

Yao, Shunchun, E-mail: epscyao@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); State Key Laboratory of Pulsed Power Laser Technology, Electronic Engineering Institute, Hefei 230037 (China); Xu, Jialong; Dong, Xuan; Zhang, Bo; Zheng, Jianping [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Lu, Jidong, E-mail: jdlu@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China)

2015-08-01

The on-line measurement of coal is extremely useful for emission control and combustion process optimization in coal-fired plant. Laser-induced breakdown spectroscopy was employed to directly analyze coal particle flow. A set of tapered tubes were proposed for beam-focusing the coal particle flow to different diameters. For optimizing the measurement of coal particle flow, the characteristics of laser-induced plasma, including optical breakdown, the relative standard deviation of repeated measurement, partial breakdown spectra ratio and line intensity, were carefully analyzed. The comparison of the plasma characteristics among coal particle flow with different diameters showed that air breakdown and the random change in plasma position relative to the collection optics could significantly influence on the line intensity and the reproducibility of measurement. It is demonstrated that the tapered tube with a diameter of 5.5 mm was particularly useful to enrich the coal particles in laser focus spot as well as to reduce the influence of air breakdown and random changes of plasma in the experiment. - Highlights: • Tapered tube was designed for beam-focusing the coal particle flow as well as enriching the particles in laser focus spot. • The characteristics of laser-induced plasma of coal particle flow were investigated carefully. • An appropriate diameter of coal particle flow was proven to benefit for improving the performance of LIBS measurement.

Use of coal-oil agglomerates for particulate gold recovery

Energy Technology Data Exchange (ETDEWEB)

Calvez, J.P.S.; Kim, M.J.; Wong, P.L.M.; Tran, T. [University of New South Wales, Sydney, NSW (Australia). School of Chemical Engineering and Industrial Chemistry

1998-09-01

The underlying principles by which gold is recovered by coal-oil agglomerates was investigated. The effects of various parameters such as oil:coal ratios, agglomerate:ore ratios, pH and coal particle size on gold recovery were evaluated using synthetic gold bearing samples, bituminous coal, and diesel oil and kerosene. The effects of sulfides on gold recovery and the depth of gold particle penetration within the agglomerates were also investigated. Results showed that gold recovery was increased by increasing agglomerate:ore ratio, decreasing oil:coal ratio and decreasing coal particle size. There was no significant difference in gold recoveries at pH range of 4-12 and at up to 5% sulfides in the feed.

Forecasting grain size distribution of coal cut by a shearer loader

Energy Technology Data Exchange (ETDEWEB)

Sikora, W; Chodura, J; Siwiec, J

1983-02-01

Analyzed are effects of shearer loader design on grain size distribution of coal, particularly on proportion of the finest size group and proportion of largest coal grains. The method developed by the IGD im. A.A. Skochinski Institute in Moscow is used. Effects of cutting tool design and mechanical coal properties are analyzed. Of the evaluated factors, two are of decisive importance: thickness of the coal chip cut by a cutting tool and coefficient of coal disintegration which characterizes coal behavior during cutting. Grain size distribution is also influenced by cutting tool geometry. Two elements of cutting tool design are of major importance: dimensions of the cutting edge and angle of attack. Effects of cutting tool design and coal mechanical properties on grain size distribution are shown in 12 diagrams. Using the forecasting method developed by the IGD im. A.A. Skochinski Institute in Moscow grain size distribution of coal cut by three shearer loaders is calculated: the KWB-3RDU with a drum 1600 mm in diameter, the KWB-6W with a drum 2500 mm in diameter, and a shearer loader being developed with a 1550 mm drum. The results of comparative evaluations are shown in two tables. 5 references.

Transformations of inorganic coal constituents in combustion systems

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. (ed.); Srinivasachar, S.; Wilemski, G.; Boni, A.A. (PSI Technology Co., Andover, MA (United States)); Kang, Shin-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Peterson, T.W.; Wendt, J.O.L.; Gallagher, N.B.; Bool, L. (Arizona Univ., Tucson, AZ (United States)); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. (Kentucky Univ., Lexingt

1992-11-01

The inorganic constituents or ash contained in pulverized coal significantly increase the environmental and economic costs of coal utilization. For example, ash particles produced during combustion may deposit on heat transfer surfaces, decreasing heat transfer rates and increasing maintenance costs. The minimization of particulate emissions often requires the installation of cleanup devices such as electrostatic precipitators, also adding to the expense of coal utilization. Despite these costly problems, a comprehensive assessment of the ash formation and had never been attempted. At the start of this program, it was hypothesized that ash deposition and ash particle emissions both depended upon the size and chemical composition of individual ash particles. Questions such as: What determines the size of individual ash particles What determines their composition Whether or not particles deposit How combustion conditions, including reactor size, affect these processes remained to be answered. In this 6-year multidisciplinary study, these issues were addressed in detail. The ambitious overall goal was the development of a comprehensive model to predict the size and chemical composition distributions of ash produced during pulverized coal combustion. Results are described.

Research on pyrolysis characteristics and kinetics of super fine and conventional pulverized coal

International Nuclear Information System (INIS)

Zhang Chaoqun; Jiang Xiumin; Wei Lihong; Wang Hui

2007-01-01

Based on isothermal thermogravimetric analysis (TGA) and kinetic equations, the optimization toolbox of MATLAB was applied to study the effects of particle size and heating rate on the pyrolysis characteristics and kinetics and to obtain the mechanism function and kinetic parameters of Yuanbaoshan coal at four different particle sizes and heating rates. The pyrolysis characteristics of the samples were analyzed using thermogravimetric (TG) curves and differential thermogravimetric (DTG) curves. The results show that the coal pyrolysis process is strongly affected by heating rate and particle size. As the heating rate increases, the temperature of volatile matter initiation increases, the total volatile matter evolved decreases and the DTG peak shifts toward higher temperature. As the particle size decreases, the temperature of volatile matter initiation of the coal sample decreases and the maximum rate of mass loss increases. In the pyrolysis of coal, the activation energies of the samples were found to increase with growing particle size and decreasing heating rate for both of the devolatilization temperature stages. In the lower temperature stage, the coal samples show a great difference in mechanism function at different particle sizes and heating rates

Interrelating the breakage and composition of mined and drill core coal

Science.gov (United States)

Wilson, Terril Edward

Particle size distribution of coal is important if the coal is to be beneficiated, or if a coal sales contract includes particle size specifications. An exploration bore core sample of coal ought to be reduced from its original cylindrical form to a particle size distribution and particle composition that reflects, insofar as possible, a process stream of raw coal it represents. Often, coal cores are reduced with a laboratory crushing machine, the product of which does not match the raw coal size distribution. This study proceeds from work in coal bore core reduction by Australian investigators. In this study, as differentiated from the Australian work, drop-shatter impact breakage followed by dry batch tumbling in steel cylinder rotated about its transverse axis are employed to characterize the core material in terms of first-order and zeroth-order breakage rate constants, which are indices of the propensity of the coal to degrade during excavation and handling. Initial drop-shatter and dry tumbling calibrations were done with synthetic cores composed of controlled low-strength concrete incorporating fly ash (as a partial substitute for Portland cement) in order to reduce material variables and conserve difficult-to-obtain coal cores. Cores of three different coalbeds--Illinois No. 6, Upper Freeport, and Pocahontas No. 5 were subjected to drop-shatter and dry batch tumbling tests to determine breakage response. First-order breakage, characterized by a first-order breakage index for each coal, occurred in the drop-shatter tests. First- and zeroth-order breakage occurred in dry batch tumbling; disappearance of coarse particles and creation of fine particles occurred in a systematic way that could be represented mathematically. Certain of the coal cores available for testing were dry and friable. Comparison of coal preparation plant feed with a crushed bore core and a bore core prepared by drop-shatter and tumbling (all from the same Illinois No.6 coal mining

Fine coal cleaning via the micro-mag process

Science.gov (United States)

Klima, Mark S.; Maronde, Carl P.; Killmeyer, Richard P.

1991-01-01

A method of cleaning particulate coal which is fed with a dense medium slurry as an inlet feed to a cyclone separator. The coal particle size distribution is in the range of from about 37 microns to about 600 microns. The dense medium comprises water and ferromagnetic particles that have a relative density in the range of from about 4.0 to about 7.0. The ferromagnetic particles of the dense medium have particle sizes of less than about 15 microns and at least a majority of the particle sizes are less than about 5 microns. In the cyclone, the particulate coal and dense-medium slurry is separated into a low gravity product stream and a high gravity produce stream wherein the differential in relative density between the two streams is not greater than about 0.2. The low gravity and high gravity streams are treated to recover the ferromagnetic particles therefrom.

Analysis of hard coal quality for narrow size fraction under 20 mm

Science.gov (United States)

Niedoba, Tomasz; Pięta, Paulina

2018-01-01

The paper presents the results of an analysis of hard coal quality diversion in narrow size fraction by using taxonomic methods. Raw material samples were collected in selected mines of Upper Silesian Industrial Region and they were classified according to the Polish classification as types 31, 34.2 and 35. Then, each size fraction was characterized in terms of the following properties: density, ash content, calorific content, volatile content, total sulfur content and analytical moisture. As a result of the analysis it can be stated that the best quality in the entire range of the tested size fractions was the 34.2 coking coal type. At the same time, in terms of price parameters, high quality of raw material characterised the following size fractions: 0-6.3 mm of 31 energetic coal type and 0-3.15 mm of 35 coking coal type. The methods of grouping (Ward's method) and agglomeration (k-means method) have shown that the size fraction below 10 mm was characterized by higher quality in all the analyzed hard coal types. However, the selected taxonomic methods do not make it possible to identify individual size fraction or hard coal types based on chosen parameters.

Experimental investigations on drying behaviour of Bulgarian brown coal in steam fluidized bed

International Nuclear Information System (INIS)

Buschsieweke, F.; Koenig, J.

1999-01-01

The main targets were: to investigate the parameters for optimizing the drying process as steam pressure, fluidization velocity and particle size; to identify the cost of drying and combustion processes considering the necessity of milling the coal (raw or dried). Test series with Bulgarian brown coal from Maritsa-East has been made. Two fractions with different particle size was got: A from 0 to 1.6 mm (0.5 mm average) and B, resp. 1.6 to 6.3 (1.7 mm). The particle size is depending on the coal moisture. The fluidized bed process with the both fractions was performed at variations of the following parameters: steam velocity (0.07 to 1.7 m/s); raw coal feed rate (4 to 16 kg/h); raw moisture (18 to 43 wt %) and pressure (1.3 and 5 bar). Also the shrinking behaviour of the coal in different pore sizes was tested. Comparing pore size of the oven dried coal to the fluidized bed dried coal, significantly higher inner surface for the oven dried coal was established. To indicate the pore size of raw coal samples were made by freeze drying. Ice expanding should cause higher inner surface compared to oven drying method but no significant difference was established. A significant increase of heat transfer of the particles from A fraction (300 to 350 W/m 2 K0 compared to B (200 to 230 W/m 2 K) was determined. The heat transfer coefficient increased at increasing of the raw coal feed rate, mostly significant for A, due to higher particle contact. In conclusion: the particle convective mechanism is predominant for the heat transfer; development of pressurized fluidized bed drying is not of interest and the question about the total expenditure for crushing and milling remains open

Grindability and combustion behavior of coal and torrefied biomass blends.

Science.gov (United States)

Gil, M V; García, R; Pevida, C; Rubiera, F

2015-09-01

Biomass samples (pine, black poplar and chestnut woodchips) were torrefied to improve their grindability before being combusted in blends with coal. Torrefaction temperatures between 240 and 300 °C and residence times between 11 and 43 min were studied. The grindability of the torrefied biomass, evaluated from the particle size distribution of the ground sample, significantly improved compared to raw biomass. Higher temperatures increased the proportion of smaller-sized particles after grinding. Torrefied chestnut woodchips (280 °C, 22 min) showed the best grinding properties. This sample was blended with coal (5-55 wt.% biomass). The addition of torrefied biomass to coal up to 15 wt.% did not significantly increase the proportion of large-sized particles after grinding. No relevant differences in the burnout value were detected between the coal and coal/torrefied biomass blends due to the high reactivity of the coal. NO and SO2 emissions decreased as the percentage of torrefied biomass in the blend with coal increased. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fundamental studies of coal liquefaction

Energy Technology Data Exchange (ETDEWEB)

1995-01-01

The authors have examined the pyrolysis of Argonne samples of Wyodak and Illinois No. 6 coal in argon, undecane, Tetralin, and water. The effects of the pyrolysis on individual particles of coal were monitored visually in a cell with diamond windows capable of operation to temperature and pressures in excess of 500{degrees}C and 3000 psi. The changes in the particles from ambient to 460{degrees}C were recorded in real time on video tape, and images were then taken from the tape record and analyzed. The study showed that in argon both coals developed tars at 350{degrees}-370{degrees}C. The tars then quickly evaporated, leaving core particles remarkably similar in size and shape to the initial particles. These observations suggest that coal does not melt nor become fully liquid when heated. Nor does the softened coal undergo crosslinking to generate coke. Rather the simple loss of volatiles leaves behind the core residue as coke. Contrary to the common view, there appears to be no link between the bond-breaking processes yielding tar and the interaction of the coal with H-donors leading to liquefaction. Water as a medium was surprising in its effect. Both coals began to shrink at 300{degrees}-350{degrees}C, with the effect appearing to be more of an erosion rather than a uniform loss of substance as seen in Tetralin. The Wyodak continued to shrink to 460{degrees}C to about half its initial size. With the Illinois No. 6 coal, however, the process reversed at around 420{degrees}C, and the particles appeared to grow with the evolution of a tar, continuing to 460{degrees}C. The authors submit that this final observation is evidence for hydrothermal synthesis of hydrocarbons at these conditions.

Coal-oil assisted flotation for the gold recovery

Energy Technology Data Exchange (ETDEWEB)

Sen, S.; Seyrankaya, A.; Cilingir, Y. [Dokuz Eylul University, Izmir (Turkey). Mining Engineering Department

2005-09-01

Using coal-oil agglomeration method for free or native gold recovery has been a research subject for many researchers over the years. In this study, a new approach 'coal-oil assisted gold flotation' was used to recover gold particles. The coal-oil-gold agglomeration process considers the preferential wetting of coal and gold particles. The method takes advantage of the greater hydrophobicity and oleophilicity of coal and gold compared to that the most gangue materials. Unlike the previous studies about coal-oil-gold agglomeration, this method uses a very small amount of coal and agglomerating agents. Some experiments were conducted on synthetic gold ore samples to reveal the reaction of the coal-oil assisted gold flotation process against the size and the number of gold particles in the feed. It was observed that there is no significant difference in process gold recoveries for feeds assaying different Au. Although there was a slight decrease for coarse gold particles, the process seems to be effective for the recovery of gold grains as coarse as 300 {mu} m. The decrease in the finest size ({lt} 53 {mu} m) is considered to be the decrease in the collision efficiency between the agglomerates and the finest gold particles. The effect of changing coal quantity for constant ore and oil amounts was also investigated. The experiments showed that the process gives very similar results for both artificial and natural ore samples; the best results have been obtained by using 30/1 coal-oil ratio.

Three-dimensional simulation of flow and combustion for pulverised coal injection

Energy Technology Data Exchange (ETDEWEB)

Guo, B.Y.; Zulli, P.; Rogers, H.; Mathieson, J.G.; Yu, A.B. [BlueScope Steel Research, Port Kembla, NSW (Australia)

2005-07-01

A three-dimensional numerical model of pulverised coal injection has been developed for simulating coal flow and combustion in the tuyere and raceway of a blast furnace. The model has been used to simulate previously reported combustion tests, which feature an inclined co-axial lance with an annular cooling gas. The predicted coal burnout agrees well with that measured for three coals with volatile contents and particle size ranging between 20.2-36.4% and particle sizes 1-200 {mu}m. Many important phenomena including flow asymmetry, recirculating flow and particle dispersion in the combustion chamber have been predicted. The current model can reproduce the experimental observations including the effects on burnout of coal flowrate and the introduction of methane for lance cooling.

Burnout behaviour of bituminous coals in air-staged combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Kluger, F.; Spliethoff, H.; Hein, K.R.G. [University of Stuttgart, Stuttgart (Germany). Inst. of Process Engineering and Power Plant (IVD)

2001-07-01

In order to determine the influence on burnout by the combustion conditions and the coal preparation, three bituminous coals sold on the world market, from three different locations in Poland, South Africa, and Australia, were studied more closely. For this purpose, the coals were ground in two different particle size ranges, which, besides the influence of the combustion conditions, such a temperature, residence time, and stoichiometry, made it possible to also investigate the impact on burnout by the coal preparation. The experiments were carried out in an electrically heated entrained-flow reactor with a thermal input of 8.5 kW. The parameters for the experiments are wall temperature (1000-1350{degree}C), air ratio (0.6-1.15) and two particle sizes (70% {lt} 75 {mu}m, 90% {lt} 75 {mu}m). The results show that in general, for increasing temperatures, the burnout quality will improve. For the Australian Illawara coal, another outcome is increased NOx emissions. Lowering the air ratio in the reduction zone leads to less NOx emission but to increased unburnt matter in ash. For the smaller particle size fraction, the analysis of the different particle sizes shows an improvement of the burnout without a change in NOx emissions. 10 refs., 10 figs., 2 tabs.

Coal combustion aerothermochemistry research. Final report

Energy Technology Data Exchange (ETDEWEB)

Witte, A.B.; Gat, N.; Denison, M.R.; Cohen, L.M.

1980-12-15

On the basis of extensive aerothermochemistry analyses, laboratory investigations, and combustor tests, significant headway has been made toward improving the understanding of combustion phenomena and scaling of high swirl pulverized coal combustors. A special attempt has been made to address the gap between scientific data available on combustion and hardware design and scaling needs. Both experimental and theoretical investigations were conducted to improve the predictive capability of combustor scaling laws. The scaling laws derived apply to volume and wall burning of pulverized coal in a slagging high-swirl combustor. They incorporate the findings of this investigation as follows: laser pyrolysis of coal at 10/sup 6/ K/sec and 2500K; effect of coal particle shape on aerodynamic drag and combustion; effect of swirl on heat transfer; coal burnout and slag capture for 20 MW/sub T/ combustor tests for fine and coarse coals; burning particle trajectories and slag capture; particle size and aerodynamic size; volatilization extent and burnout fraction; and preheat level. As a result of this work, the following has been gained: an increased understanding of basic burning mechanisms in high-swirl combustors and an improved model for predicting combustor performance which is intended to impact hardware design and scaling in the near term.

Effect of multiphase radiation on coal combustion in a pulverized coal jet flame

International Nuclear Information System (INIS)

Wu, Bifen; Roy, Somesh P.; Zhao, Xinyu; Modest, Michael F.

2017-01-01

The accurate modeling of coal combustion requires detailed radiative heat transfer models for both gaseous combustion products and solid coal particles. A multiphase Monte Carlo ray tracing (MCRT) radiation solver is developed in this work to simulate a laboratory-scale pulverized coal flame. The MCRT solver considers radiative interactions between coal particles and three major combustion products (CO 2 , H 2 O, and CO). A line-by-line spectral database for the gas phase and a size-dependent nongray correlation for the solid phase are employed to account for the nongray effects. The flame structure is significantly altered by considering nongray radiation and the lift-off height of the flame increases by approximately 35%, compared to the simulation without radiation. Radiation is also found to affect the evolution of coal particles considerably as it takes over as the dominant mode of heat transfer for medium-to-large coal particles downstream of the flame. To investigate the respective effects of spectral models for the gas and solid phases, a Planck-mean-based gray gas model and a size-independent gray particle model are applied in a frozen-field analysis of a steady-state snapshot of the flame. The gray gas approximation considerably underestimates the radiative source terms for both the gas phase and the solid phase. The gray coal approximation also leads to under-prediction of the particle emission and absorption. However, the level of under-prediction is not as significant as that resulting from the employment of the gray gas model. Finally, the effect of the spectral property of ash on radiation is also investigated and found to be insignificant for the present target flame. - Highlights: • A Monte Carlo–based nongray radiation solver is developed to study effects of radiation. • Radiation alters the lift-off height, and the distribution of temperature andspecies for the target flame. • Radiation alters the heat transfer mechanism of medium

The secondary release of mercury in coal fly ash-based flue-gas mercury removal technology.

Science.gov (United States)

He, Jingfeng; Duan, Chenlong; Lei, Mingzhe; Zhu, Xuemei

2016-01-01

The secondary release of mercury from coal fly ash is a negative by-product from coal-fired power plants, and requires effective control to reduce environmental pollution. Analysing particle size distribution and composition of the coal fly ash produced by different mercury removing technologies indicates that the particles are generally less than 0.5 mm in size and are composed mainly of SiO2, Al2O3, and Fe2O3. The relationships between mercury concentration in the coal fly ash, its particle size, and loss of ignition were studied using different mercury removing approaches. The research indicates that the coal fly ash's mercury levels are significantly higher after injecting activated carbon or brominating activated carbon when compared to regular cooperating-pollution control technology. This is particularly true for particle size ranges of >0.125, 0.075-0.125, and 0.05-0.075 mm. Leaching experiments revealed the secondary release of mercury in discarded coal fly ash. The concentration of mercury in the coal fly ash increases as the quantity of injecting activated carbon or brominating activated carbon increases. The leached concentrations of mercury increase as the particle size of the coal fly ash increases. Therefore, the secondary release of mercury can be controlled by adding suitable activated carbon or brominating activated carbon when disposing of coal fly ash. Adding CaBr2 before coal combustion in the boiler also helps control the secondary release of mercury, by increasing the Hg(2+) concentration in the leachate. This work provides a theoretical foundation for controlling and removing mercury in coal fly ash disposal.

Picobubble column flotation of fine coal

Energy Technology Data Exchange (ETDEWEB)

Daniel Tao; Samuel Yu; Xiaohua Zhou; R.Q. Honaker; B.K. Parekh [University of Kentucky, Lexington, KY (United States). Department of Mining Engineering

2008-01-15

Froth flotation is widely used in the coal industry to clean -28 mesh (0.6 mm) or -100 mesh (0.15 mm) fine coal. A successful recovery of particles by flotation depends on efficient particle-bubble collision and attachment with minimal subsequent particle detachment from bubble. Flotation is effective in a narrow size range, nominally 10-100 {mu}m, beyond which the flotation efficiency drops sharply. A fundamental analysis has shown that use of picobubbles can significantly improve the flotation recovery of particles by increasing the probability of collision and attachment and reducing the probability of detachment. A specially designed column with a picobubble generator has been developed for enhanced recovery of fine coal particles. Picobubbles were produced based on the hydrodynamic cavitation principle. Experimental results have shown that the use of picobubbles in a 5-cm diameter column flotation increased the combustible recovery of a highly floatable coal by up to 10% and that of a poorly floatable coal by up to 40%, depending on the feed rate, collector dosage, and other flotation conditions. 14 refs.

NOx, FINE PARTICLE AND TOXIC METAL EMISSIONS FROM THE COMBUSTION OF SEWAGE SLUDGE/COAL MIXTURES: A SYSTEMATIC ASSESSMENT

Energy Technology Data Exchange (ETDEWEB)

Jost O.L. Wendt

2002-08-15

This research project focuses on pollutants from the combustion of mixtures of dried municipal sewage sludge (MSS) and coal. The objective is to determine the relationship between (1) fraction sludge in the sludge/coal mixture, and (2) combustion conditions on (a) NOx concentrations in the exhaust, (b) the size segregated fine and ultra-fine particle composition in the exhaust, and (c) the partitioning of toxic metals between vapor and condenses phases, within the process. The proposed study will be conducted in concert with an existing ongoing research on toxic metal partitioning mechanisms for very well characterized pulverized coals alone. Both high NOx and low NOx combustion conditions will be investigated (unstaged and staged combustion). Tradeoffs between CO2 control, NOx control, and inorganic fine particle and toxic metal emissions will be determined. Previous research has yielded data on trace metal partitioning for MSS by itself, with natural gas assist, for coal plus MSS combustion together, and for coal alone. We have re-evaluated the inhalation health effects of ash aerosol from combustion of MSS both by itself and also together with coal. We have concluded that ash from the co-combustion of MSS and coal is very much worse from an inhalation health point of view, than ash from either MSS by itself or coal by itself. The reason is that ZnO is not the ''bad actor'' as had been suspected before, but the culprit is, rather, sulfated Zn. The MSS supplies the Zn and the coal supplies the sulfur, and so it is the combination of coal and MSS that makes that process environmentally bad. If MSS is to be burned, it should be burned without coal, in the absence of sulfur.

Technological and economic aspects of coal biodesulfurisation.

Science.gov (United States)

Klein, J

1998-01-01

The sulfur found in coal is either part of the molecular coal structure (organically bound sulfur), is contained in minerals such as pyrite (FeS2), or occurs in minor quantities in the form of sulfate and elemental sulfur. When pyrite crystals are finely distributed within the coal matrix, mechanical cleaning can only remove part of the pyrite. It can, however, be removed by microbial action requiring only mild conditions. The process involves simple equipment, almost no chemicals, but relatively long reaction times, and treatment of iron sulfate containing process water. Different process configurations are possible, depending on the coal particle size. Coal with particle sizes of less than 0.5 mm is preferably desulfurised in slurry reactors, while lump coal (> 0.5 mm) should be treated in heaps. Investment and operating costs are estimated for different process configurations on an industrial scale. Concerning the organically bound sulfur in coal there is up to now no promising biochemical pathway for the degradation and/or desulfurisation of such compounds.

NO emission characteristics of superfine pulverized coal combustion in the O2/CO2 atmosphere

International Nuclear Information System (INIS)

Liu, Jiaxun; Gao, Shan; Jiang, Xiumin; Shen, Jun; Zhang, Hai

2014-01-01

Highlights: • Superfine pulverized coal combustion in O 2 /CO 2 atmosphere is a new promising technology. • NO emissions of superfine pulverized coal combustion in O 2 /CO 2 mixture were focused. • Coal particle sizes have significant effects on NO emissions in O 2 /CO 2 combustion. - Abstract: The combination of O 2 /CO 2 combustion and superfine pulverized coal combustion technology can make full use of their respective merits, and solve certain inherent disadvantages of each technology. The technology of superfine pulverized coal combustion in the O 2 /CO 2 atmosphere is easy and feasible to be retrofitted with few reconstructions on the existing devices. It will become a useful and promising method in the future. In this paper, a one-dimensional drop-tube furnace system was adopted to study the NO emission characteristics of superfine pulverized coal combustion in the O 2 /CO 2 atmosphere. The effects of coal particle size, coal quality, furnace temperature, stoichiometric ratio, etc. were analyzed. It is important to note that coal particle sizes have significant influence on NO emissions in the O 2 /CO 2 combustion. For the homogeneous NO reduction, smaller coal particles can inhibit the homogeneous NO formations under fuel-rich combustion conditions, while it becomes disadvantageous for fuel-lean combustion. However, under any conditions, heterogeneous reduction is always more significant for smaller coal particle sizes, which have smoother pore surfaces and simpler pore structures. The results from this fundamental research will provide technical support for better understanding and developing this new combustion process

The identification of unusual microscopic features in coal and their derived chars: Influence on coal fluidized bed combustion

Energy Technology Data Exchange (ETDEWEB)

Valentim, B. [Centro de Geologia da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Lemos de Sousa, M.J. [Centro de Geologia da Universidade do Porto, Praca de Gomes Teixeira, 4099-002 Porto (Portugal); Abelha, P.; Boavida, D.; Gulyurtlu, I. [Departamento de Engenharia Energetica e Controlo Ambiental (DEECA), Instituto Nacional de Engenharia, Tecnologia e Inovacao (INETI), Estrada do Paco do Lumiar, 22, Edif. J, 1649-038, Lisboa (Portugal)

2006-06-06

During the petrographic study of seven feed coals from different origins, it was found that these coals presented microfeatures such as: material size, shape, weathering, thermally affected particles and contamination. After devolatilization under fluidized bed conditions, some chars presented the consequences of the above mentioned microfeatures, i.e., unreacted coal, unswelled particles, coatings and microstratification. Since the amounts of the microfeatures observed were low (less than 1%), the present study is essentially observational/descriptional. However, it seems very likely, from the observations that were made, that the occurrence of one or more of these microfeatures in coal, depending on their kind and abundance, may have significant effect on the coal devolatilization. (author)

Developmental effects of aerosols and coal burning particles in zebrafish embryos

International Nuclear Information System (INIS)

Olivares, Alba; Drooge, Barend L. van; Casado, Marta; Prats, Eva; Serra, Montserrat; Ven, Leo T. van der; Kamstra, Jorke H.; Hamers, Timo; Hermsen, Sanne; Grimalt, Joan O.; Piña, Benjamin

2013-01-01

Embryo toxicity of particles generated by combustion processes is of special concern for human health. A significant part of these toxic effects is linked to the binding of some pollutants (like polycyclic aromatic hydrocarbons or PAHs) to the Aryl hydrocarbon Receptor (AhR) and the activation of target genes, like the cytochrome P4501A. This activity was analyzed for ambient air and coal-combustion particle extracts in zebrafish embryos (the cyp1aDarT assay) and in two single-cell bioassays: the yeast-based YCM-RYA and the DR-luc (rat cells) assay. Observed AhR ligand activity of samples generally correlated to the predicted toxic effect according to their PAH composition, except for one of the coal combustion samples with an anomalously high activity in the cyp1aDarT assay. This sample induced deformities in zebrafish embryos. We concluded that the combination of morphological and molecular assays may detect embryonic toxic effects that cannot be predicted from chemical analyses or single-cell bioassays. -- Highlights: ► Samples from air particulated matter and coal waste gob showed embryo toxicity in zebrafish. ► PAHs composition of samples does not adequately predict the toxic effects in zebrafish. ► Active coal waste gob samples show maximal AhR-ligand activity and induce deformations in zebrafish embryos. -- Aerosols and coal burning particles showed a strong developmental toxicity in zebrafish, in a degree that cannot be directly predicted from chemical analyses or single-cell bioassays

Soot, unburned carbon and ultrafine particle emissions from air- and oxy-coal flames

International Nuclear Information System (INIS)

Morris, W.J.; Yu, Dunxi; Wendt, J.O.L.

2010-01-01

Oxy-coal combustion is one possible solution for the mitigation of greenhouse gases. In this process coal is burned in oxygen, rather than air, and the temperatures in the boiler are mitigated by recycling flue gases, so that the inlet mixture may contain either 27 % O 2 to match adiabatic flame temperatures, or 32 % O 2 to match gaseous radiation heat fluxes in the combustion chamber. However, a major issue for heat transfer from coal combustion is the radiative heat transmission from soot. For this research, air and oxy coal firing were compared regarding the emission of soot. A 100 kW down-fired laboratory combustor was used to determine effects of switching from air to oxy-firing on soot, unburned carbon and ultrafine particle emissions from practical pulverized coal flames. Of interest here were potential chemical effects of substitution of the N 2 in air by CO 2 in practical pulverized coal flames. The oxy-coal configuration investigated used once-through CO 2 , simulating cleaned flue gas recycle with all contaminants and water removed. Three coals were each burned in: a) air, b) 27 % O 2 / 73 % CO 2 , c) 32 % O 2 / 68 % CO 2 . Tests were conducted at (nominally) 3 %, 2 %, 1 % and 0 % O 2 in the exhaust (dry basis). For each condition, particulate samples were iso kinetically withdrawn far from the radiant zone, and analyzed using a photoacoustic analyzer (PA) for black carbon, a scanning mobility particle sizer (SMPS) for ultrafine particles, and a total sample loss on ignition (LOI) method for unburned carbon in ash. Data suggest that at low stoichiometric ratios, ultrafine particles consist primarily of black carbon, which, for the bituminous coal, is produced in lesser amounts under oxy-fired conditions than under the air-fired condition, even when adiabatic flame temperatures are matched. However, significant changes in mineral matter vaporization were not observed unless the flames were hotter. These and other results are interpreted in the light of

Further Investigations on Simultaneous Ultrasonic Coal Flotation

Directory of Open Access Journals (Sweden)

Safak Gokhan Ozkan

2017-09-01

Full Text Available This study investigates the flotation performance of a representative hard coal slime sample (d80 particle size of minus 0.2 mm obtained from the Prosper-Haniel coal preparation plant located in Bottrop, Germany. Flotation was carried out with a newly designed flotation cell refurbished from an old ultrasonic cleaning bath (2.5 L volume equipped with a single frequency (35 kHz and two different power levels (80–160 W and a sub-aeration-type flotation machine operating at a stable impeller speed (1200 rpm and air rate (2.5 L/min. The reagent combination for conventional and simultaneous ultrasonic coal flotation tests was Ekofol-440 at variable dosages (40–300 g/t with controlling water temperature (20–25 °C at natural pH (6.5–7.0. The batch coal flotation results were analyzed by comparing the combustible recovery (% and separation efficiency (% values, taking mass yield and ash concentrations of the froths and tailings into account. It was found that simultaneous ultrasonic coal flotation increased yield and recovery values of the floated products with lower ash values than the conventional flotation despite using similar reagent dosages. Furthermore, particle size distribution of the ultrasonically treated and untreated coals was measured. Finely distributed coal particles seemed to be agglomerated during the ultrasonic treatment, while ash-forming slimes were removed by hydrodynamic cavitation.

Agglomeration of coal fines for premium fuel application

International Nuclear Information System (INIS)

Atalay, A.; Zaman, M.D.

1992-01-01

This paper reports on fine coal in liquid suspension, which can be agglomerated in a number of ways. One of the oldest procedures involves the addition of electrolyte to the suspension to cause a reduction in the zeta potential and allow colliding particles to agglomerate. A second method involves the use of polymeric flocculants to bridge between particles. Both of these technologies are being used in the wastewater treatment plants for removal of fine waste particles from contaminated water. A third method involves the addition of a second immiscible liquid preferentially to wet the particles and cause adhesion by capillary interfacial forces. While the bonding forces in the first two methods are small and result in rather weak and voluminous agglomerates, the third method is postulated to produce more dense and much stronger agglomerates. In the case of fine coals, the carbonaceous constituents can be agglomerated and recovered from the aqueous suspension with many different coagulants. Inorganic or ash-forming constituents are also agglomerated along with the fine coal particles. As the froth floatation, agglomeration using coal and colloidal dust to effect a separation. Froth floatation, however, becomes less effective where extremely fine particles of cal must be treated or if there is considerable clay-size particle present. In contrast, there appears to be virtually no lower limit on the particle size suitable for agglomeration uses

PM1 particles at coal- and gas-fired power plant work areas.

Science.gov (United States)

Hicks, Jeffrey B; McCarthy, Sheila A; Mezei, Gabor; Sayes, Christie M

2012-03-01

With the increased interest in the possible adverse health effects attributed to inhalation of fine particle matter, this study was conducted to gather preliminary information about workplace exposures at coal- and gas-fired power plants to fine particles (PM(1); i.e. <1 μm) and ultrafine particles (i.e. <0.1 μm). Combustion of fossil fuel is known to produce fine particles, and due to their proximity and durations of exposure, power plant workers could be a group of individuals who experience high chronic exposures to these types of particles. The results of a series of real-time instrument measurements showed that concentrations of PM(1) were elevated in some locations in power plants. The highest concentrations were in locations near combustion sources, indicating that combustion materials were leaking from conventional fossil fuel-fired boilers or it was associated with emission plume downwash. Concentrations were the lowest inside air-conditioned control rooms where PM(1) were present at levels similar to or lower than upwind concentrations. Microscopic examinations indicate that PM(1) at the coal-fired plants are dominated by vitrified spheres, although there were also unusual elongated particles. Most of the PM(1) were attached to larger coal fly ash particles that may affect where and how they could be deposited in the lung.

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.

Micro-scale grain-size analysis and magnetic properties of coal-fired power plant fly ash and its relevance for environmental magnetic pollution studies

Energy Technology Data Exchange (ETDEWEB)

Blaha, U.; Sapkota, B.; Appel, E.; Stanjek, H.; Rosler, W. [University of Tubingen, Tubingen (Germany). Inst. of Geoscience

2008-11-15

Two fly ash samples from a black coal-fired power plant (Bexbach, Germany) were investigated for their magnetic properties, particle structure, grain-size distribution and chemical composition. Grain-size distribution was determined on bulk samples and on magnetic extracts. Magnetic susceptibility of different grain-size fractions was analyzed with respect to the according amount of fractions, high- and low-temperature dependence of magnetic susceptibility and thermal demagnetization of IRM identified magnetite and hematite as magnetic phases. Magnetic spherules were quantitatively extracted from bulk fly ash samples and examined using SEM/EDX analysis. Particle morphology and grain-size analysis on the magnetically extracted material were studied. Individual spherule types were identified and internal structures of selected polished particles were investigated by SEM and EDX analyses. Main element contents of the internal structures which consist of 'magnetite' crystals and 'glassy' matrix were systematically determined and statistically assessed. The chemical data of the micro-scale structures in the magnetic spherules were compared with XRF data from bulk material, revealing the relative element distribution in composed magnetic spherules. Comparison of the bulk sample grain-size (0.5-300 {mu}m) and grain-size spectra from magnetic extracts (1-186.5 {mu}m) shows that strongly magnetic particles mainly occur in the fine fractions of < 63 {mu}m. This study comprises a comprehensive characterization of coal-fired power plant fly ash, using magnetic, chemical, and microscopic methods. The results can serve as reference data for a variety of environmental magnetic studies.

Burnout of pulverized biomass particles in large scale boiler - Single particle model approach

Energy Technology Data Exchange (ETDEWEB)

Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero [VTT Technical Research Centre of Finland, Box 1603, 40101 Jyvaeskylae (Finland); Soerensen, Lasse Holst [ReaTech/ReAddit, Frederiksborgsveij 399, Niels Bohr, DK-4000 Roskilde (Denmark); Clausen, Soennik [Risoe National Laboratory, DK-4000 Roskilde (Denmark); Berg, Mogens [ENERGI E2 A/S, A.C. Meyers Vaenge 9, DK-2450 Copenhagen SV (Denmark)

2010-05-15

Burning of coal and biomass particles are studied and compared by measurements in an entrained flow reactor and by modelling. The results are applied to study the burning of pulverized biomass in a large scale utility boiler originally planned for coal. A simplified single particle approach, where the particle combustion model is coupled with one-dimensional equation of motion of the particle, is applied for the calculation of the burnout in the boiler. The particle size of biomass can be much larger than that of coal to reach complete burnout due to lower density and greater reactivity. The burner location and the trajectories of the particles might be optimised to maximise the residence time and burnout. (author)

Characteristic Study of Shenmu Bituminous Coal Combustion with Online TG-MS-FTIR

Science.gov (United States)

Pan, Guanfu

2018-01-01

The combustion characteristics of Shenmu bituminous pulverized coal (SBC) were comprehensively investigated with a combined TG-MS-FTIR system by considering the effect of particle size, heating rate and total flowrate. The combustion products were accurately quantified by normalization and numerical analysis of MS results. The results indicate that the decrease of the particle size, heating rate and total flowrate result in lower ignition and burnout temperatures. The activation energy tends to be lower with smaller particle size, lower heating rate and total flowrate. The MS and FTIR results demonstrate that lower concentrations of different products, such as NO, NO2, HCN, CH4 and SO2 were produced with smaller particle size, slower heating rate and lower total flowrate. The decrease of particle size would lead to more contact area with oxygen and slower heating rate could provide more sufficient time for the diffusion. High total flowrate would reduce the oxygen adsorbability on the coal particle surface and shorten the residence time of oxygen, which makes the ignition difficult to occur. This work will guide to understand the combustion kinetics of pulverized coals and be beneficial to control the formation of pollutants.

Numerical research of heat and mass transfer during low-temperature ignition of a coal particle

Directory of Open Access Journals (Sweden)

Glushkov Dmitrii O.

2015-01-01

Full Text Available Numerical researches have been carried out to study the influence of air flow temperature and a fossil fuel particle rate on sufficient conditions of ignition in a “coal particle - air” system. Developed mathematical model takes into account interconnected processes of heat transfer in a coal particle and gas area, thermal decomposition of organic material, diffusion and gas-phase oxidation of volatiles, heating of a coke (carbon and its heterogeneous ignition. The effect of low-temperature (about 600 K ignition for a single coal particle is impossible even at variation of its rate (radius from 0.05 mm to 0.5 mm. Nevertheless this process is possible for group of particles (two, three, et al. situated at close-range from each other. The physical aspects of the problem are discussed.

Transformations of inorganic coal constituents in combustion systems. Volume 1, sections 1--5: Final report

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. [ed.; Srinivasachar, S.; Wilemski, G.; Boni, A.A. [PSI Technology Co., Andover, MA (United States); Kang, Shin-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Peterson, T.W.; Wendt, J.O.L.; Gallagher, N.B.; Bool, L. [Arizona Univ., Tucson, AZ (United States); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. [Kentucky Univ., Lexington, KY (United States)

1992-11-01

The inorganic constituents or ash contained in pulverized coal significantly increase the environmental and economic costs of coal utilization. For example, ash particles produced during combustion may deposit on heat transfer surfaces, decreasing heat transfer rates and increasing maintenance costs. The minimization of particulate emissions often requires the installation of cleanup devices such as electrostatic precipitators, also adding to the expense of coal utilization. Despite these costly problems, a comprehensive assessment of the ash formation and had never been attempted. At the start of this program, it was hypothesized that ash deposition and ash particle emissions both depended upon the size and chemical composition of individual ash particles. Questions such as: What determines the size of individual ash particles? What determines their composition? Whether or not particles deposit? How combustion conditions, including reactor size, affect these processes? remained to be answered. In this 6-year multidisciplinary study, these issues were addressed in detail. The ambitious overall goal was the development of a comprehensive model to predict the size and chemical composition distributions of ash produced during pulverized coal combustion. Results are described.

Modeling coal combustion behavior in an ironmaking blast furnace raceway: model development and applications

Energy Technology Data Exchange (ETDEWEB)

Maldonado, D.; Austin, P.R.; Zulli, P.; Guo B. [BlueScope Steel Research Laboratories, Port Kembla, NSW (Australia)

2009-03-15

A numerical model has been developed and validated for the investigation of coal combustion phenomena under blast furnace operating conditions. The model is fully three-dimensional, with a broad capacity to analyze significant operational and equipment design changes. The model was used in a number of studies, including: Effect of cooling gas type in coaxial lance arrangements. It was found that oxygen cooling improves coal burnout by 7% compared with natural gas cooling under conditions that have the same amount of oxygen enrichment in the hot blast. Effect of coal particle size distribution. It was found that during two similar periods of operation at Port Kembla's BF6, a difference in PCI capability could be attributed to the difference in coal size distribution. Effect of longer tuyeres. Longer tuyeres were installed at Port Kembla's BF5, leading to its reline scheduled for March 2009. The model predicted an increase in blast velocity at the tuyere nose due to the combustion of volatiles within the tuyere, with implications for tuyere pressure drop and PCI capability. Effect of lance tip geometry. A number of alternate designs were studied, with the best-performing designs promoting the dispersion of the coal particles. It was also found that the base case design promoted size segregation of the coal particles, forcing smaller coal particles to one side of the plume, leaving larger coal particles on the other side. 11 refs., 15 figs., 4 tabs.

Coal flotation - bench-scale study. Flotacao de carvao estudo em escala de bancada

Energy Technology Data Exchange (ETDEWEB)

Campos, A.R. de; Almeida, S L.M. de; Santos, A.T. dos

1979-01-01

Run-of-mine coal and pre-washed coal from Santa Catarina, Brazil, were characterized using washability curves and by particle size analysis after crushing. Bench-scale froth flotation tests were then conducted with the pre-washed coal. Kerosene and diesel oil were used as the collectors, and pine oil as the frother. The influence of starch (as depressor) on flotation was also studied. The effects of feed particle size, pH, collector addition, frother addition, depressor addition and flotation time were investigated. A 9.5% ash content coal could be obtained with a mass recovery of about 29%. (17 refs.)

Effect of the grinding behaviour of coal blends on coal utilisation for combustion

Energy Technology Data Exchange (ETDEWEB)

Rubiera, F.; Arenillas, A.; Fuente, E.; Pis, J.J. [Inst. Nacional del Carbon, CSIC, Oviedo (Spain); Miles, N. [School of Chemical, Environmental and Mining Engineering, Nottingham Univ. (United Kingdom)

1999-11-01

Grinding of a high volatile bituminous coal was performed in three comminution devices: Raymond Mill (RM), Rolls Crusher (RC) and Ball Mill (BM). The pulverised samples were sieved to obtain four particle size fractions, and temperature-programmed combustion (TPC) was used for the evaluation of their combustion behaviour. In addition, three coals of different hardness and rank were mixed in various proportions in order to compare the combustibility characteristics of the binary coal blends with those of the individual coals. The effect of coal blending on grindability was also studied. It was found that grindability was non-additive especially when coals of very different hardgrove grindability index (HGI) were blended. The combustion studies also suggested that there exists an interaction between individual coals when they are burnt as a blend. (orig.)

Particle-based characterisation of pulverised coals and chars for carbon burnout studies

Energy Technology Data Exchange (ETDEWEB)

Gibbins, J.R.; Seitz, M.H.; Kennedy, S.M.; Beeley, T.J.; Riley, G.S. [Imperial College of Science, Technology and Medicine, London (United Kingdom). Mechanical Engineering Department

1999-07-01

The study of individual particle properties, as opposed to averaged behaviour of differing particles, was carried out for the combustion of coals and chars using optical microscopy and digital image processing. Chars from entrained flow reactors and corresponding pulverized fuel samples were characterized to examine possible char particle origins for real heterogeneous particles. 7 refs., 5 figs., 1 tab.

Characterization and supply of coal-based fuels

Energy Technology Data Exchange (ETDEWEB)

1989-06-01

Contract objectives are as follows: Develop fuel specifications to serve combustor requirements. Select coals having appropriate compositional and quality characteristics as well as an economically attractive reserve base; Provide quality assurance for both the parent coals and the fuel forms; and deliver premium coal-based fuels to combustor developers as needed for their contract work. Progress is discussed, particulary in slurry fuel preparation and particle size distribution.

Coal preparation and coal cleaning in the dry process; Kanshiki sentaku to coal cleaning

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Z; Morikawa, M; Fujii, Y [Okayama University, Okayama (Japan). Faculty of Engineering

1996-09-01

Because the wet process has a problem such as waste water treatment, coal cleaning in the dry process was discussed. When a fluidized bed (using glass beads and calcium carbonate) is utilized instead of the heavy liquid, the fluidized bed will have apparent density as the liquid does, whereas the relative relationship therewith determines whether a substance having been put into the fluidized bed will float or sink. This is utilized for coals. In addition, two powder constituents of A and B may be wanted to be separated using the fluidized extraction process (similar to the liquid-liquid extraction process). In such a case, a fluidized bed in which both constituents are mixed is added with a third constituent C (which will not mix with A, but mix well with B), where the constituents are separated into A and (B + C), and the (B + C) constituent is separated further by using a sieve. If coal has the coal content mixed with ash content and pulverized, it turns into particle groups which have distributions in grain size and density. Groups having higher density may contain more ash, and those having lower density less ash. In addition, the ash content depends also on the grain size. The ash content may be classified by using simultaneously wind classification (for density and grain size) and a sieve (for grain size). This inference may be expanded to consideration of constructing a multi-stage fluidized bed classification tower. 12 figs., 5 tabs.

Partitioning behaviour of natural radionuclides during combustion of coal in thermal power plants

International Nuclear Information System (INIS)

Sahu, S.K.; Tiwari, M.; Bhangare, R.C.; Ajmal, P.Y.; Pandit, G.G.

2014-01-01

All fossil fuels contain low levels of naturally occurring radioactive substances. The environmental impact of radionuclide-containing waste products from coal combustion is an important issue. These radionuclides vaporize in the hot portions of the coal combustor and then return to the solid phase in cooler downstream zones. Indian coal used in power plants generally has high ash yield (35-45%) and is of low quality. In the burning process of coal, minerals undergo thermal decomposition, fusion, disintegration, and agglomeration. A major portion of elements in the boiler enter into slag or bottom ash, and the rest of the inorganic materials find their way into the flue gas, in fly ash or vapor. Fly and bottom ash are significant sources of exposure to these radionuclides. In the present study, coal and ash samples collected from six thermal power stations were analyzed to determine their natural radioactivity content and the partitioning behavior of these radionuclides was carried out by tracing their activities in fly and bottom ashes. The partitioning of radionuclides is strongly dependent on the size of associated ash particle. Polonium-210 was mostly associated with the finest fraction and showed large variation with particle size whereas 232 Th showed least dependence on the particle size. The high activities of all radionuclides in fly ashes than that of bottom ashes thus may be due to strong affinity of the nuclides towards the finer particle fractions. All the radionuclide distribution favored small particle sizes

Study on the Inference Factors of Huangling Coking Coal Pyrolysis

Science.gov (United States)

Du, Meili; Yang, Zongyi; Fan, Jinwen

2018-01-01

In order to reasonably and efficiently utilize Huangling coking coal resource, coal particle, heating rate, holding time, pyrolysis temperature and others factors were dicussed for the influence of those factor on Huangling coking coal pyrolysis products. Several kinds of coal blending for coking experiments were carried out with different kinds of coal such as Huangling coking coal, Xida coal with high ash low sufur, Xinghuo fat coal with hign sulfur, Zhongxingyi coking coal with high sulfur, Hucun lean coal, mixed meager and lean coal. The results shown that the optimal coal particle size distribution was 0.5~1.5mm, the optimal heating rate was 8°C/min, the optimal holding time was 15min, the optimal pyrolysis temperature was 800°C for Huangling coking coal pyrolysis, the tar yield increased from 4.7% to 11.2%. The maximum tar yield of coal blending for coking under the best single factor experiment condition was 10.65% when the proportio of Huangling coking coal was 52%.

Fluidised bed gasification of low grade South African coals

CSIR Research Space (South Africa)

North, BC

2006-09-01

Full Text Available gasifiers. Fluidised bed Entrained flow Coal particle size 0.5 mm – 5 mm 0 – 0.5 mm Coal moisture Dry Dry/slurry Coal type Non-caking coals Any coal Ash in coal < 60% < 30% Gasification agents Air/steam/oxygen Steam/oxygen Gasification... properties important for fluidised bed gasification are: square4 Coal reactivity in atmospheres of CO2 and H2O square4 Caking index and free swelling index (FSI) square4 Ash fusion temperature (AFT) 5.1 Coal reactivity The gasifcation reactions (1...

Optimization of hydrogen and syngas production from PKS gasification by using coal bottom ash.

Science.gov (United States)

Shahbaz, Muhammad; Yusup, Suzana; Inayat, Abrar; Patrick, David Onoja; Pratama, Angga; Ammar, Muhamamd

2017-10-01

Catalytic steam gasification of palm kernel shell is investigated to optimize operating parameters for hydrogen and syngas production using TGA-MS setup. RSM is used for experimental design and evaluating the effect of temperature, particle size, CaO/biomass ratio, and coal bottom ash wt% on hydrogen and syngas. Hydrogen production appears highly sensitive to all factors, especially temperature and coal bottom ash wt%. In case of syngas, the order of parametric influence is: CaO/biomass>coal bottom ash wt%>temperature>particle size. The significant catalytic effect of coal bottom ash is due to the presence of Fe 2 O 3 , MgO, Al 2 O 3 , and CaO. A temperature of 692°C, coal bottom ash wt% of 0.07, CaO/biomass of 1.42, and particle size of 0.75mm are the optimum conditions for augmented yield of hydrogen and syngas. The production of hydrogen and syngas is 1.5% higher in the pilot scale gasifier as compared to TGA-MS setup. Copyright © 2017 Elsevier Ltd. All rights reserved.

Emission characteristics for gaseous- and size-segregated particulate PAHs in coal combustion flue gas from circulating fluidized bed (CFB) boiler.

Science.gov (United States)

Wang, Ruwei; Liu, Guijian; Sun, Ruoyu; Yousaf, Balal; Wang, Jizhong; Liu, Rongqiong; Zhang, Hong

2018-07-01

The partitioning behavior of polycyclic aromatic hydrocarbons (PAHs) between gaseous and particulate phases from coal-fired power plants (CFPPs) is critically important to predict PAH removal by dust control devices. In this study, 16 US-EPA priority PAHs in gaseous and size-segregated particulate phases at the inlet and outlet of the fabric filter unit (FFs) of a circulating fluidized bed (CFB) boiler were analyzed. The partitioning mechanisms of PAHs between gaseous and particulate phases and in particles of different size classes were investigated. We found that the removal efficiencies of PAHs are 45.59% and 70.67-89.06% for gaseous and particulate phases, respectively. The gaseous phase mainly contains low molecular weight (LMW) PAHs (2- and 3-ring PAHs), which is quite different from the particulate phase that mainly contains medium and high molecular weight (MMW and HMW) PAHs (4- to 6-ring PAHs). The fractions of LMW PAHs show a declining trend with the decrease of particle size. The gas-particle partitioning of PAHs is primarily controlled by organic carbon absorption, in addition, it has a clear dependence on the particle sizes. Plot of log (TPAH/PM) against logD p shows that all slope values were below -1, suggesting that PAHs were mainly adsorbed to particulates. The adsorption effect of PAHs in size-segregated PMs for HMW PAHs is more evident than LMW PAHs. The particle size distributions (PSDs) of individual PAHs show that most of PAHs exhibit bi-model structures, with one mode peaking in the accumulation size range (2.1-1.1 μm) and another mode peaking in coarse size range (5.8-4.7 μm). The intensities of these two peaks vary in function of ring number of PAHs, which is likely attributed to Kelvin effect that the less volatile HMW PAH species preferentially condense onto the finer particulates. The emission factor of PAHs was calculated as 3.53 mg/kg of coal burned, with overall mean EF PAH of 0.55 and 2.98 mg/kg for gaseous and particulate

Formation and filtration of flakes from coal slurries

Energy Technology Data Exchange (ETDEWEB)

Sing, B K; Clement, M; Juentgen, H

1977-06-01

Size and size distribution of flakes are much influenced by the type and concentration of the flocculation agent. The coal particles show different behaviour to that of the dirt particles. The ph-value and the concentration of electrolytes also influence flocculation. They change the surface properties of the solid material as well as the flocculability of the flocculant.

Particle size distribution control of Pt particles used for particle gun

Science.gov (United States)

Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

2017-07-01

The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

Heat and Mass Transfer at Hot Surface Ignition of Coal Particle

OpenAIRE

Glushkov Dmitrii O.; Kosintsev Andrey. G.; Shlegel Nikita E.; Vershinina Ksenia Yu.

2015-01-01

This paper describes the experimental investigations of the characteristics of heat and mass transfer during the conductive heating of a coal particle. We have established the boundary conditions of combustion initiation, and the conditions of thermal decomposition and solid fuel particles decay, characterized by the temperature of a heat source, and the duration of the respective stages.

An alternative method for determining particle-size distribution of forest road aggregate and soil with large-sized particles

Science.gov (United States)

Hakjun Rhee; Randy B. Foltz; James L. Fridley; Finn Krogstad; Deborah S. Page-Dumroese

2014-01-01

Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by...

PASSIVE CONTROL OF PARTICLE DISPERSION IN A PARTICLE-LADEN CIRCULAR JET USING ELLIPTIC CO-ANNULAR FLOW: A MEANS FOR IMPROVING UTILIZATION AND EMISSION REDUCTIONS IN PULVERIZED COAL BURNER

Energy Technology Data Exchange (ETDEWEB)

Ahsan R. Choudhuri

2003-06-01

A passive control technology utilizing elliptic co-flow to control the particle flinging and particle dispersion in a particle (coal)-laden flow was investigated using experimental and numerical techniques. Preferential concentration of particles occurs in particle-laden jets used in pulverized coal burner and causes uncontrollable NO{sub x} formation due to inhomogeneous local stoichiometry. This particular project was aimed at characterizing the near-field flow behavior of elliptic coaxial jets. The knowledge gained from the project will serve as the basis of further investigation on fluid-particle interactions in an asymmetric coaxial jet flow-field and thus is important to improve the design of pulverized coal burners where non-homogeneity of particle concentration causes increased NO{sub x} formation.

Investigation of factors influencing the attrition breakage of coal

Energy Technology Data Exchange (ETDEWEB)

Oberholzer, V.; van der Walt, J. [North West University, Mmabatho (South Africa). School of Chemical & Minerals Engineering

2009-04-15

The presence of fines (particles smaller than 6 mm in diameter) causes hydrodynamic problems in gasifiers and therefore it is of great importance to minimize the amount of fine coal in the feed. This serves as motivation for understanding coal's breakage mechanisms, which could lead to the ability to predict the generation of fines. The aim of this project was to simulate the pulsating effect of the conveyor belt in order to investigate factors influencing the breakage. Results indicated that an increased initial particle size had an increasing effect in the amount of fines generated. Weathering had an insignificant effect on the breakage of coal. To conclude, a breakage model was developed to describe the rate of breakage out of the top size when a combination of two breakage modes is present.

Characterization of a coal tailing deposit for zero waste mine in the Brazilian coal field of Santa Catarina

International Nuclear Information System (INIS)

Amaral Filho, J.R.; Schneider, I.A.H.; Tubino, R.M.C.; Brum de, I.A.S.; Miltzarek, G.; Sampaio, C.H.

2010-01-01

Coal tailings deposits in Brazil are occupying large areas of land while also generating acid mine drainage (AMD) that includes heavy metals. This paper described an analytical study of a typical coal tailings deposit. The study objective was to separate low density, intermediate density, and high density fractions for future reuse. Particle size analysis, disymmetric studies, X-ray diffraction, and tests conducted to determine ash, total sulphur, and acid bases were conducted in order to characterize the coal tailings samples. Results of the study demonstrated a size distribution of 67 percent coarse, 14 percent fine, and 19 percent ultra-fine particles. The gravimetric concentration method was used to recover 34.2 percent of the total deposit for future energy use. Approximately 9.2 percent of the remaining deposit was a pyrite concentrate. The acid generating potential of the remaining materials was reduced by approximately 60 percent. 9 refs., 1 tab., 2 figs.

Fluidized bed combustion of single coal char particles at high CO{sub 2} concentration

Energy Technology Data Exchange (ETDEWEB)

Scala, F.; Chirone, R. [CNR, Naples (Italy)

2010-12-15

Combustion of single coal char particles was studied at 850{sup o}C in a lab-scale fluidized bed at high CO{sub 2} concentration, typical of oxyfiring conditions. The burning rate of the particles was followed as a function of time by continuously measuring the outlet CO and O{sub 2} concentrations. Some preliminary evaluations on the significance of homogeneous CO oxidation in the reactor and of carbon gasification by CO{sub 2} in the char were also carried out. Results showed that the carbon burning rate increases with oxygen concentration and char particle size. The particle temperature is approximately equal to that of the bed up to an oxygen concentration of 2%, but it is considerably higher for larger oxygen concentrations. Both CO{sub 2} gasification of char and homogeneous CO oxidation are not negligible. The gasification reaction rate is slow and it is likely to be controlled by intrinsic kinetics. During purely gasification conditions the extent of carbon loss due to particle attrition by abrasion (estimated from the carbon mass balance) appears to be much more important than under combustion conditions.

Pulverized coal burnout in blast furnace simulated by a drop tube furnace

Energy Technology Data Exchange (ETDEWEB)

Du, Shan-Wen [Steel and Aluminum Research and Development Department, China Steel Corporation, Kaohsiung 812 (China); Chen, Wei-Hsin [Department of Greenergy, National University of Tainan, Tainan 700 (China); Lucas, John A. [School of Engineering of the University of Newcastle, Callaghan, NSW 2308 (Australia)

2010-02-15

Reactions of pulverized coal injection (PCI) in a blast furnace were simulated using a drop tube furnace (DTF) to investigate the burnout behavior of a number of coals and coal blends. For the coals with the fuel ratio ranging from 1.36 to 6.22, the experimental results indicated that the burnout increased with decreasing the fuel ratio, except for certain coals departing from the general trend. One of the coals with the fuel ratio of 6.22 has shown its merit in combustion, implying that the blending ratio of the coal in PCI operation can be raised for a higher coke replacement ratio. The experiments also suggested that increasing blast temperature was an efficient countermeasure for promoting the combustibility of the injected coals. Higher fuel burnout could be achieved when the particle size of coal was reduced from 60-100 to 100-200 mesh. However, once the size of the tested coals was in the range of 200 and 325 mesh, the burnout could not be improved further, resulting from the agglomeration of fine particles. Considering coal blend reactions, the blending ratio of coals in PCI may be adjusted by the individual coal burnout rather than by the fuel ratio. (author)

Froth flotation as a promising method of coal preparation in Brazil

Energy Technology Data Exchange (ETDEWEB)

Campos, A.R. de; Almeida, S L.M. de; Santos, A.T. dos

1979-01-01

Run-of-mine coal and pre-washed coal from Santa Catarina, Brazil, were characterized using washability curves, and by particle analysis after crushing. Bench-scale froth flotation tests were then conducted with the pre-washed coal, using kerosene and diesel oil as the collectors and pine oil as the frother. The influence of starch (as depressor) on flotation was also studied. The effects of feed particle size; pH; collector, frother and depressor additions; and flotation time were investigated. A 9.5% ash content coal was obtained with a mass recovery of about 29%. (17 refs.)

Particle size determination

International Nuclear Information System (INIS)

Burr, K.J.

1979-01-01

A specification is given for an apparatus to provide a completely automatic testing cycle to determine the proportion of particles of less than a predetermined size in one of a number of fluid suspensions. Monitoring of the particle concentration during part of the process can be carried out by an x-ray source and detector. (U.K.)

Burnout prediction using advance image analysis coal characterization techniques

Energy Technology Data Exchange (ETDEWEB)

Edward Lester; Dave Watts; Michael Cloke [University of Nottingham, Nottingham (United Kingdom). School of Chemical Environmental and Mining Engineering

2003-07-01

The link between petrographic composition and burnout has been investigated previously by the authors. However, these predictions were based on 'bulk' properties of the coal, including the proportion of each maceral or the reflectance of the macerals in the whole sample. Combustion studies relating burnout with microlithotype analysis, or similar, remain less common partly because the technique is more complex than maceral analysis. Despite this, it is likely that any burnout prediction based on petrographic characteristics will become more accurate if it includes information about the maceral associations and the size of each particle. Chars from 13 coals, 106-125 micron size fractions, were prepared using a Drop Tube Furnace (DTF) at 1300{degree}C and 200 millisecond and 1% Oxygen. These chars were then refired in the DTF at 1300{degree}C 5% oxygen and residence times of 200, 400 and 600 milliseconds. The progressive burnout of each char was compared with the characteristics of the initial coals. This paper presents an extension of previous studies in that it relates combustion behaviour to coals that have been characterized on a particle by particle basis using advanced image analysis techniques. 13 refs., 7 figs.

A dynamic mathematical model for microbial removal of pyritic sulfur from coal.

Science.gov (United States)

Kargi, F; Weissman, J G

1984-06-01

A dynamic mathematical model has been developed to describe microbial desulfurization of coal by Thiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption-description constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm(3) mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leaching.

Crack identification and evolution law in the vibration failure process of loaded coal

Science.gov (United States)

Li, Chengwu; Ai, Dihao; Sun, Xiaoyuan; Xie, Beijing

2017-08-01

To study the characteristics of coal cracks produced in the vibration failure process, we set up a static load and static and dynamic combination load failure test simulation system, prepared with different particle size, formation pressure, and firmness coefficient coal samples. Through static load damage testing of coal samples and then dynamic load (vibration exciter) and static (jack) combination destructive testing, the crack images of coal samples under the load condition were obtained. Combined with digital image processing technology, an algorithm of crack identification with high precision and in real-time is proposed. With the crack features of the coal samples under different load conditions as the research object, we analyzed the distribution of cracks on the surface of the coal samples and the factors influencing crack evolution using the proposed algorithm and a high-resolution industrial camera. Experimental results showed that the major portion of the crack after excitation is located in the rear of the coal sample where the vibration exciter cannot act. Under the same disturbance conditions, crack size and particle size exhibit a positive correlation, while crack size and formation pressure exhibit a negative correlation. Soft coal is more likely to lead to crack evolution than hard coal, and more easily causes instability failure. The experimental results and crack identification algorithm provide a solid basis for the prevention and control of instability and failure of coal and rock mass, and they are helpful in improving the monitoring method of coal and rock dynamic disasters.

Mineralogy and characterization of deposited particles of the aero sediments collected in the vicinity of power plants and the open pit coal mine: Kolubara (Serbia).

Science.gov (United States)

Cvetković, Željko; Logar, Mihovil; Rosić, Aleksandra

2013-05-01

In this paper, particular attention was paid to the presence of aerosol solid particles, which occurred mainly as a result of exploitation and coal combustion in the thermal power plants of the Kolubara basin. Not all of the particles created by this type of anthropogenic pollution have an equal impact on human health, but it largely depends on their size and shape. The mineralogical composition and particle size distribution in the samples of aero sediments were defined. The samples were collected close to the power plant and open pit coal mine, in the winter and summer period during the year 2007. The sampling was performed by using precipitators placed in eight locations within the territory of the Lazarevac municipality. In order to characterize the sedimentary particles, several methods were applied: microscopy, SEM-EDX and X-ray powder diffraction. The concentration of aero sediments was also determined during the test period. Variety in the mineralogical composition and particle size depends on the position of the measuring sites, geology of the locations, the annual period of collecting as well as possible interactions. By applying the mentioned methods, the presence of inhalational and respiratory particles variously distributed in the winter and in the summer period was established. The most common minerals are quartz and feldspar. The presence of gypsum, clay minerals, calcite and dolomite as secondary minerals was determined, as well as the participation of organic and inorganic amorphic matter. The presence of quartz as a toxic mineral has a particular impact on human health.

Pyrolysis of superfine pulverized coal. Part 4. Evolution of functionalities in chars

International Nuclear Information System (INIS)

Liu, Jiaxun; Ma, Yang; Luo, Lei; Ma, Junfang; Zhang, Hai; Jiang, Xiumin

2017-01-01

Highlights: • A combination of XPS and NMR is adopted for analyzing char chemical structures during superfine pulverized coal pyrolysis. • The chemisorbed NO can be transformed into pyridine N with the favor of adjacent oxygenated groups in chars. • Particle size has significant influence on oxygen-containing configurations in chars. - Abstract: The properties of the coal-derived char play crucial roles in coal conversion reactions and the formation of air pollutants. The nascent char is highly reactive due to the existence of numerous free radicals, active sites, and organic functional groups on its surface. Here, we showed that a combination of nuclear magnetic resonance spectroscopy (NMR) and X-ray photoelectron spectroscopy (XPS) techniques is an effective and precise way to characterize the occurrence, distribution, and evolution of organic functionalities in coal chars. Using these methods, we explored detailed information about chemical features of superfine pulverized coal chars in different atmospheres, and we also discussed the influence of particle size on the evolutionary behavior of functionalities. Results indicate that, in both N_2 and CO_2 atmospheres, the content of C−O species increases with the reduction in char particle sizes. This increment facilitates the heterogeneous reduction of NOx on char surfaces. The chemisorbed NO is susceptible to being incorporated into chars, and being transformed into pyridine-type nitrogen with the favor of adjacent oxygen-containing groups. Moreover, the significant increment in oxygen-containing groups with the reduction of particle size is further confirmed through "1"3C NMR analysis. It was shown that there is an excellent correlation between estimates derived from XPS and NMR for oxygen configuration. The findings from this work provide some new insights into NOx reduction mechanisms and shed light on the practical application of superfine pulverized coal in the future.

Drying kinetics characteristic of Indonesia lignite coal (IBC) using lab scale fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Kang, TaeJin; Jeon, DoMan; Namkung, Hueon; Jang, DongHa; Jeon, Youngshin; Kim, Hyungtaek [Ajou Univ., Suwon (Korea, Republic of). Div. of Energy Systems Research

2013-07-01

Recent instability of energy market arouse a lot of interest about coal which has a tremendous amount of proven coal reserves worldwide. South Korea hold the second rank by importing 80 million tons of coal in 2007 following by Japan. Among various coals, there is disused coal. It's called Low Rank Coal (LRC). Drying process has to be preceded before being utilized as power plant. In this study, drying kinetics of LRC is induced by using a fixed bed reactor. The drying kinetics was deduced from particle size, the inlet gas temperature, the drying time, the gas velocity, and the L/D ratio. The consideration on Reynold's number was taken for correction of gas velocity, particle size, and the L/D ratio was taken for correction packing height of coal. It can be found that active drying of free water and phase boundary reaction is suitable mechanism through the fixed bed reactor experiments.

Theoretical basis for transfer of laboratory test results of grain size distribution of coal to real object

Energy Technology Data Exchange (ETDEWEB)

Sikora, W; Chodura, J [Politechnika Sladska, Gliwice (Poland). Instytut Mechanizacji Gornictwa

1989-01-01

Evaluates a method for forecasting size distribution of black coal mined by shearer loaders in one coal seam. Laboratory tests for determining coal comminution during cutting and haulage along the face are analyzed. Methods for forecasting grain size distribution of coal under operational conditions using formulae developed on the basis of laboratory tests are discussed. Recommendations for design of a test stand and test conditions are discussed. A laboratory stand should accurately model operational conditions of coal cutting, especially dimensions of the individual elements of the shearer loader, geometry of the cutting drum and cutting tools, and strength characteristics of the coal seam. 9 refs.

Seasonal and particle size-dependent variations in gas/particle partitioning of PCDD/Fs

International Nuclear Information System (INIS)

Lee, Se-Jin; Ale, Debaki; Chang, Yoon-Seok; Oh, Jeong-Eun; Shin, Sun Kyoung

2008-01-01

This study monitored particle size-dependent variations in atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Two gas/particle partitioning models, the subcooled liquid vapor pressure (P L 0 ) and the octanol-air partition coefficient (K OA ) model, were applied to each particle sizes. The regression coefficients of each fraction against the gas/particle partition coefficient (K P ) were similar for separated particles within the same sample set but differed for particles collected during different periods. Gas/particle partitioning calculated from the integral of fractions was similar to that of size-segregated particles and previously measured bulk values. Despite the different behaviors and production mechanisms of atmospheric particles of different sizes, PCDD/F partitioning of each size range was controlled by meteorological conditions such as atmospheric temperature, O 3 and UV, which reflects no source related with certain particle size ranges but mixed urban sources within this city. Our observations emphasize that when assessing environmental and health effects, the movement of PCDD/Fs in air should be considered in conjunction with particle size in addition to the bulk aerosol. - Gas/particle partitioning of atmospheric PCDD/Fs for different particle sizes reflects the impacts of emitters of different size ranges

Coal-char combustion in a fluidised bed reactor

Energy Technology Data Exchange (ETDEWEB)

Mehrotra, S.P.; Pande, M. [Indian Institute of Technolgy, Kanpur (India)

2001-12-01

Combustion of bituminous coal chars ranging from 0.8 mm to 1.8 mm has been studied in a fluidised bed reactor at temperatures ranging from 500 to 850{sup o}C. The fluidised bed consists of inert sand particles of average size of 0.5 mm and reactive coal char particles. A heat balance has been worked out to calculate the rate of combustion of char from measured incremental changes in the bed temperature during combustion. Investigations on partially burnt particles suggest that the ash layer which builds up around the burning core of char particles is non-flaking and the particles burn in a shrinking core manner. Analysis of rate data indicates that the rate of combustion is controlled by chemical reaction kinetics, though diffusion of oxygen through the bundary layer begins to influence the overall reaction kinetics at higher temperatures. The burnt out time varies linearly with particle size. Activation energy for the chemical reaction control regime is found to be around 68 kJ/mole.

Pyrolysis of superfine pulverized coal. Part 3. Mechanisms of nitrogen-containing species formation

International Nuclear Information System (INIS)

Liu, Jiaxun; Jiang, Xiumin; Shen, Jun; Zhang, Hai

2015-01-01

Highlights: • NH 3 and NO formation mechanisms during superfine pulverized coal pyrolysis are investigated. • Influences of temperature, heating rate, particle size, atmosphere, and acid wash on the NH 3 and NO formation are analyzed. • Transformations of nitrogen-containing structures in coal/char during pyrolysis are recognized through XPS observation. • Relationships among nitrogen-containing gaseous species during pyrolysis are discussed. - Abstract: With more stringent regulations being implemented, elucidating the formation mechanisms of nitrogen-containing species during the initial pyrolysis step becomes important for developing new NO x control strategies. However, there is a lack of agreement on the origins of NO x precursors during coal pyrolysis, in spite of extensive investigations. Hence, it is important to achieve a more precise knowledge of the formation mechanisms of nitrogen-contain species during coal pyrolysis. In this paper, pyrolysis experiments of superfine pulverized coal were performed in a fixed bed at low heating rates. The influences of temperature, coal type, particle size and atmosphere on the NH 3 and NO evolution were discussed. There is a central theme to develop knowledge of the relationship between particle sizes and evolving behaviors of nitrogen-containing species. Furthermore, the catalytic role of inherent minerals in coal was proved to be effective on the partitioning of nitrogen during coal pyrolysis. In addition, the conversion pathways of heteroaromatic nitrogen structures in coal/char during pyrolysis were recognized through the X-ray photoelectron spectroscopy (XPS) analysis. Large quantities of pyridinic and quanternary nitrogen functionalities were formed during the thermal degradation. Finally, the relationships among the nitrogen-containing gaseous species during coal pyrolysis were discussed. In brief, a comprehensive picture of the volatile-nitrogen partitioning during coal pyrolysis is obtained in this

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

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.

Application of a three-dimensional network model to coal dewatering

Energy Technology Data Exchange (ETDEWEB)

Qamar, I.

1986-01-01

A bond-flow correlated network model has been successfully used to calculate equilibrium desaturation curves, single phase permeabilities and two phase flow properties (dewatering curves) for coal filter cakes. A new method of pore volume assignment is presented in which the pore volume occupied by the large pores (which give a capillary pressure less than 0.5 psia) is assigned to the nodes and the rest is distributed to the bonds according to the pore size distribution. The micrographic pore size distribution, used as an input, is determined experimentally. Equilibrium desaturation curves for -32 mesh, -200 mesh and -100 + 200 mesh coal cakes (Pittsburgh Seam Coal), formed with distilled water, have been calculated. The results for six -32 mesh coal cakes formed with surfactants show that the effect of surfactants can be accounted for by modifying one of the model parameters - the entry diameter constant. A correlation is presented to estimate the modified entry diameter constant using experimentally determined surface tension and contact angle values. The size distribution of particles in dispersed state has been correlated with that in the cake which in turn has been correlated with the pore size distribution. An equilibrium desaturation curve has been successfully calculated for -32 mesh Pittsburgh Seam coal using the pore size distribution estimated from the dispersed particle size distribution. Calculated single phase permeabilities, using a bond-flow correlated network and a simple cubic lattice, agree with the experimental values better than a bond-correlated network using a face-centered cubic lattice.

EXPERIMENTS AND COMPUTATIONAL MODELING OF PULVERIZED-COAL IGNITION; FINAL

International Nuclear Information System (INIS)

Samuel Owusu-Ofori; John C. Chen

1999-01-01

Under typical conditions of pulverized-coal combustion, which is characterized by fine particles heated at very high rates, there is currently a lack of certainty regarding the ignition mechanism of bituminous and lower rank coals as well as the ignition rate of reaction. furthermore, there have been no previous studies aimed at examining these factors under various experimental conditions, such as particle size, oxygen concentration, and heating rate. Finally, there is a need to improve current mathematical models of ignition to realistically and accurately depict the particle-to-particle variations that exist within a coal sample. Such a model is needed to extract useful reaction parameters from ignition studies, and to interpret ignition data in a more meaningful way. The authors propose to examine fundamental aspects of coal ignition through (1) experiments to determine the ignition temperature of various coals by direct measurement, and (2) modeling of the ignition process to derive rate constants and to provide a more insightful interpretation of data from ignition experiments. The authors propose to use a novel laser-based ignition experiment to achieve their first objective. Laser-ignition experiments offer the distinct advantage of easy optical access to the particles because of the absence of a furnace or radiating walls, and thus permit direct observation and particle temperature measurement. The ignition temperature of different coals under various experimental conditions can therefore be easily determined by direct measurement using two-color pyrometry. The ignition rate-constants, when the ignition occurs heterogeneously, and the particle heating rates will both be determined from analyses based on these measurements

Effective Diffusion Coefficients in Coal Chars

DEFF Research Database (Denmark)

Johnsson, Jan Erik; Jensen, Anker

2001-01-01

Knowledge of effective diffusion coefficients in char particles is important when interpreting experimental reactivity measurements and modeling char combustion or NO and N2O reduction. In this work, NO and N2O reaction with a bituminous coal char was studied in a fixed-bed quartz glass reactor....... In the case of strong pore diffusion limitations, the error in the interpretation of experimental results using the mean pore radius could be a factor of 5 on the intrinsic rate constant. For an average coal char reacting with oxygen at 1300 K, this would be the case for particle sizes larger than about 50...

Modes of occurrence of potentially hazardous elements in coal: levels of confidence

Science.gov (United States)

Finkelman, R.B.

1994-01-01

The modes of occurrence of the potentially hazardous elements in coal will be of significance in any attempt to reduce their mobilization due to coal combustion. Antimony and selenium may be present in solid solution in pyrite, as minute accessory sulfides dispersed throughout the organic matrix, or in organic association. Because of these modes of occurrence it is anticipated that less than 50% of these elements will be routinely removed by conventional coal cleaning procedures. Arsenic and mercury occur primarily in late-stage coarse-grained pyrite therefore physical coal cleaning procedures should be successful in removing substantial proportions of these elements. Cadmium occurs in sphalerite and lead in galena. Both of these minerals exhibit a wide range of particle sizes and textural relations. Depending on the particle size and textural relations, physical coal cleaning may remove as little as 25% of these elements or as much as 75%. Manganese in bituminous coal occurs in carbonates, especially siderite. Physical coal cleaning should remove a substantial proportion of this element. More information is needed to elucidate the modes of occurrence of beryllium, chromium, cobalt, and nickel. ?? 1994.

Biological removal of sulfur from coal flotation concentrate by culture isolated from coal washery plant tailing dump

Energy Technology Data Exchange (ETDEWEB)

Jorjani, E. [Azad University, Tehran (Iran). Mining Engineering Dept.

2005-10-15

A combination of flotation and microbial leaching processes was used to achieve acceptable level of sulfur and ash in Tabas coal sample of Iran. Representative sample of the minus 500 micron size fraction was subjected to flotation separation for the removal of ash and sulfur. The final concentrate with recovery, combustion value and sulfur content of 86.03, 86.45 and 1.35% respectively was achieved at pH 8 and following reagent dosage and operating conditions: collector: diesel oil (1200 g/ton), frother: MIBC (5%) + pine oil (95%) with concentration of 120 (g/ton), depressant: sodium silicate (1000 g/ton), particle size: {lt} 500 {mu} m and pulp density: 7%. Because of fine distribution of sulfur on Tabas coal macerals and lithotypes, high percentage of total sulfur (79.9%) is distributed in flotation concentrate and only 20.1% is yielded in the tails. So microbial leaching using a species isolated from coal washery plant tailing dump was used in batch system to remove sulfur from flotation concentrate. The conditions were optimized for the maximum removal of sulfur. These conditions were found to be pH of 2, particle size less than 0.18 mm; pulp density: 8%, temperature: 30 {sup o}C, shaking rate: 150 rpm conditions. Total sulfur and ash content was reduced by bioleaching from 13.55 and 1.35 in flotation concentrate to 9.47 and 0.55 in the final leached concentrate, a reduction of 35 and 61.9% respectively. Sterilization of coal adversely affects the sulfur reduction. The results suggest that the isolated culture is sufficiently effective for depyritization of Tabas coal flotation concentrate in stirred system.

New particle formation in the fresh flue-gas plume from a coal-fired power plant: effect of flue-gas cleaning

Science.gov (United States)

Mylläri, Fanni; Asmi, Eija; Anttila, Tatu; Saukko, Erkka; Vakkari, Ville; Pirjola, Liisa; Hillamo, Risto; Laurila, Tuomas; Häyrinen, Anna; Rautiainen, Jani; Lihavainen, Heikki; O'Connor, Ewan; Niemelä, Ville; Keskinen, Jorma; Dal Maso, Miikka; Rönkkö, Topi

2016-06-01

Atmospheric emissions, including particle number and size distribution, from a 726 MWth coal-fired power plant were studied experimentally from a power plant stack and flue-gas plume dispersing in the atmosphere. Experiments were conducted under two different flue-gas cleaning conditions. The results were utilized in a plume dispersion and dilution model taking into account particle formation precursor (H2SO4 resulted from the oxidation of emitted SO2) and assessment related to nucleation rates. The experiments showed that the primary emissions of particles and SO2 were effectively reduced by flue-gas desulfurization and fabric filters, especially the emissions of particles smaller than 200 nm in diameter. Primary pollutant concentrations reached background levels in 200-300 s. However, the atmospheric measurements indicated that new particles larger than 2.5 nm are formed in the flue-gas plume, even in the very early phases of atmospheric ageing. The effective number emission of nucleated particles were several orders of magnitude higher than the primary particle emission. Modelling studies indicate that regardless of continuing dilution of the flue gas, nucleation precursor (H2SO4 from SO2 oxidation) concentrations remain relatively constant. In addition, results indicate that flue-gas nucleation is more efficient than predicted by atmospheric aerosol modelling. In particular, the observation of the new particle formation with rather low flue-gas SO2 concentrations changes the current understanding of the air quality effects of coal combustion. The results can be used to evaluate optimal ways to achieve better air quality, particularly in polluted areas like India and China.

Investigation of flow behaviour of coal particles in a pilot-scale fluidized bed gasifier (FBG) using radiotracer technique.

Science.gov (United States)

Pant, H J; Sharma, V K; Kamudu, M Vidya; Prakash, S G; Krishanamoorthy, S; Anandam, G; Rao, P Seshubabu; Ramani, N V S; Singh, Gursharan; Sonde, R R

2009-09-01

Knowledge of residence time distribution (RTD), mean residence time (MRT) and degree of axial mixing of solid phase is required for efficient operation of coal gasification process. Radiotracer technique was used to measure the RTD of coal particles in a pilot-scale fluidized bed gasifier (FBG). Two different radiotracers i.e. lanthanum-140 and gold-198 labeled coal particles (100 gm) were independently used as radiotracers. The radiotracer was instantaneously injected into the coal feed line and monitored at the ash extraction line at the bottom and gas outlet at the top 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 tanks-in-series model. The simulation of RTD data indicated good degree of mixing with small fraction of the feed material bypassing/short-circuiting from the bottom of the gasifier. The results of the investigation were found useful for optimizing the design and operation of the FBG, and scale-up of the gasification process.

Gasifier feed: Tailor-made from Illinois coals

Energy Technology Data Exchange (ETDEWEB)

Ehrlinger, H.P. III.

1991-01-01

The purpose of this research is to develop a coal slurry from waste streams using Illinois coal that is ideally suited for a gasification feed. The principle items to be studied are (1) methods of concentrating pyrite and decreasing other ash forming minerals into a high grade gasification feed using froth flotation and gravity separation techniques; (2) chemical and particle size analyses of coal slurries; (3) determination of how that slurry can be densified and to what degree of densification is optimum from the pumpability and combustibility analyses; and (4) reactivity studies.

Fuel briquettes from brown coals of Yakutia

Energy Technology Data Exchange (ETDEWEB)

L.A. Nikolaeva; V.G. Latyshev; O.N. Burenina [Russian Academy of Sciences, Yakutsk (Russian Federation). Institute of Oil and Gas Problems

2009-04-15

Experimental data on the development of technology for the manufacture of briquetted fuel from brown coals with the use of various petroleum binders are presented. The influence of the moisture content, the coal particle-size composition, the binder type and concentration, the compacting pressure, and heat treatment regimes on the mechanical properties of the materials was studied. The optimal compositions and optimal values of the engineering parameters for the production of graded briquetted fuel from brown coals of the Kangalassy deposit in the Republic of Sakha (Yakutia) were established.

Particle Size and Crystal Phase Effects in Fischer-Tropsch Catalysts

Directory of Open Access Journals (Sweden)

Jin-Xun Liu

2017-08-01

Full Text Available Fischer-Tropsch synthesis (FTS is an increasingly important approach for producing liquid fuels and chemicals via syngas—that is, synthesis gas, a mixture of carbon monoxide and hydrogen—generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.

Relationship between polycyclic aromatic hydrocarbons (PAHs) and particle size in dated core sediments in Lake Lianhuan, Northeast China

International Nuclear Information System (INIS)

Sun, Li; Zang, Shuying

2013-01-01

Atmospheric particle associated with pyrogenic polycyclic aromatic hydrocarbons (PAHs) poses serious threats to human health by inhalation exposure, especially in semiarid areas. Hence, the distributions of PAHs and particle size in two core sediments collected from Lake Lianhuan, Northeast China were studied. The sediments were dated radiometrically, and particle size distribution and PAH concentration were evaluated and potential human health risk was assessed. From 1980 to 2007, the dominant PAHs in the two cores were 2- and 3-ring PAHs, and the concentrations of 3–6 ring PAHs gradually increased from the early 1990s. Diagnostic ratios indicated that pyrogenic PAHs were the main sources of PAHs which changed over time from combustions of wood and coal to liquid fossil fuel sources. Fine particles ( 125 μm were found. Future research should focus on the seven carcinogenic pyrogenic PAHs due to a rapidly increasing trend since 1995 based on the assessment of toxic equivalency factors. - Highlights: • PAHs and particle size in core sediments were used to evaluate the role of eolian particles in delivering pyrogenic PAHs. • Changes of PAH sources closely followed local historical socioeconomic development since 1980s. • Changes of particulate sources from eolian to lacustrine reflected the evolving history of the lake. • Significant correlations between pyrogenic PAHs and eolian particles indicated potential risk from inhalation exposure. • Petroleum source PAHs are likely to stick to coarse particles and accumulate in lake sediments by surface runoff

POC-scale testing of a dry triboelectrostatic separator for fine coal cleaning

Energy Technology Data Exchange (ETDEWEB)

Yoon, R.H.; Luttrell, G.H.; Adel, G.T. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

1995-11-01

Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both the ash and sulfur contents of run-of-mine coals. The extent of cleaning depends on the liberation characteristics of the coal, which generally improve with reducing particle size. however, since most of the advanced technologies are wet processes, the clean coal product must be dewatered before it can be transported and burned in conventional boilers. This additional treatment step significantly increases the processing cost and makes the industrial applicability of these advanced technologies much less attractive. In order to avoid problems associated with fine coal dewatering, researchers at the Pittsburgh Energy Technology Center (PETC) developed a novel triboelectrostatic separation (TES) process that can remove mineral matter from dry coal. In this technique, finely pulverized coal is brought into contact with a material (such as copper) having a work function intermediate to that of the carbonaceous material and associated mineral matter. Carbonaceous particles having a relatively low work function become positively charged, while particles of mineral matter having significantly higher work functions become negatively charged. once the particles become selectively charged, a separation can be achieved by passing the particle stream through an electrically charged field. Details related to the triboelectrostatic charging phenomenon have been discussed elsewhere (Inculet, 1984).

Automatic particle-size analysis of HTGR recycle fuel

International Nuclear Information System (INIS)

Mack, J.E.; Pechin, W.H.

1977-09-01

An automatic particle-size analyzer was designed, fabricated, tested, and put into operation measuring and counting HTGR recycle fuel particles. The particle-size analyzer can be used for particles in all stages of fabrication, from the loaded, uncarbonized weak acid resin up to fully-coated Biso or Triso particles. The device handles microspheres in the range of 300 to 1000 μm at rates up to 2000 per minute, measuring the diameter of each particle to determine the size distribution of the sample, and simultaneously determining the total number of particles. 10 figures

The effect of the particulate phase on coal biosolubilisation mediated by Trichoderma atroviride in a slurry bioreactor

Energy Technology Data Exchange (ETDEWEB)

Oboirien, B.O.; Burton, S.G. [Bioprocess Engineering Research Unit, Department of Chemical Engineering, University of Cape Town, Rondebosch, 7701 (South Africa); Cowan, D. [Bioprocess Engineering Research Unit, Department of Chemical Engineering, University of Cape Town, Rondebosch, 7701 (South Africa); Department of Biotechnology, University of the Western Cape, Belville (South Africa); Harrison, S.T.L.

2008-02-15

Low rank coal is currently under-utilised because of its low calorific value and high moisture and sulphur content. Its solubilisation by both bacterial and fungal cultures has been reported, the latter more commonly. Coal biosolubilisation processes have potential to convert low rank coal to either a clean, cost-effective energy source or complex aromatic compounds for biocatalytic conversion to value-added products. This can lead to an increased utilisation of low rank coal. In this study, the key variables of the slurry that affect biosolubilisation of low rank coal by Trichoderma atroviride in submerged culture were investigated. Results showed that the key operating variables that influence coal biosolubilisation in the slurry bioreactor are coal loading and particle size affecting available surface area. These factors affect the surface area available for coal biosolubilisation. The optimum coal loading occurred between 5 and 10% (w/v); an increase above this optimum led to inhibition of the fungal culture of T. atroviride (ES11) by fragmentation of the fungal mycelium. A decrease in particle size fraction led to an increase in the degree of coal solubilisation. Coal biosolubilisation was shown to increase 4-fold when particle size was decreased from 600-850 {mu}m to 150-300 {mu}m. A 28% biosolubilisation of coal of 150-300 {mu}m, characterised by a surface specific area of 2.17 cm{sup 2} g{sup -} {sup 1}, was measured as coal weight loss over 14 days at solids loading at 5%. This can be compared with a 7.8% coal weight loss at 600-850 {mu}m diameters (0.54 cm{sup 2} g{sup -} {sup 1}). Soluble phenolic compounds are not a significant product of the coal biosolubilisation process. The change in pH observed in the presence of both coal and fungi was independent of coal loading and was not directly related to the extent of coal solubilisation. While soluble intermediates were observed as total organic, further metabolism resulted in complete oxidation of a

Production of fines during co-combustion of coal with biomass fuels by fragmentation and attrition

Energy Technology Data Exchange (ETDEWEB)

I. Gulyurtlu; D. Boavida; H. Lopes (and others) [DEECA-INETI, Lisbon (Portugal)

2005-07-01

Results are reported from a project funded by the RFCS Programme of the European Union. The aim is to investigate, experimentally and by modeling, the production of fine char and ash particles during co-combustion of coal with wastes and biofuels in circulating fluidized bed. Work was undertaken at installations of different scales. Polish and Colombian coals were base fuels. The additional fuels were two sewage sludges. Bed temperature, feeding system, sand particle size, devolatilisation behaviour and char burn-out were studied to verify their influence on the fine particle production. Modeling was also carried out to understand the mechanisms of fragmentation and attrition. Samples from bed and cyclone were collected to determine particle size distributions. 11 refs.

Investigations into detonations of coal dust suspensions in oxygen-nitrogen

Energy Technology Data Exchange (ETDEWEB)

Edwards, D.; Fearnley, P.; Nettleton, M.

1987-03-01

The effect of particle size (practically monodispersed), volatile content and composition of gaseous oxygen-nitrogen mixtures on initiating flame acceleration rates in coal dust suspensions is investigated experimentally. Description is given of apparatus, material used and experiments carried out. The authors discusses: microwave interferograms, pressure oscillograms for various oxygen-nitrogen mixtures; development of ionization front speed in relation to distance from diaphragm; effect of composition on shock wave advance rates. It is concluded that: microwave interferometry can successfully be used in recording initiation of coal dust suspension detonations; ignition of confined coal dust suspensions by shock waves originated by detonation front in stoichiometric oxyacetylene mixtures can be explained by heating of coal particles in shock compression stream to ignition temperature (1000 K) by combined convection and radiation heat transfer. 16 refs.

Kinetics of coal pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Seery, D.J.; Freihaut, J.D.; Proscia, W.M. (United Technologies Research Center, East Hartford, CT (USA)); Howard, J.B.; Peters, W.; Hsu, J.; Hajaligol, M.; Sarofim, A. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Jenkins, R.; Mallin, J.; Espindola-Merin, B. (Pennsylvania State Univ., University Park, PA (USA)); Essenhigh, R.; Misra, M.K. (Ohio State Univ., Columbus, OH (USA))

1989-07-01

This report contains results of a coordinated, multi-laboratory investigation of coal devolatilization. Data is reported pertaining to the devolatilization for bituminous coals over three orders of magnitude in apparent heating rate (100 to 100,000 + {degree}C/sec), over two orders of magnitude in particle size (20 to 700 microns), final particle temperatures from 400 to 1600{degree}C, heat transfer modes ranging from convection to radiative, ambient pressure ranging from near vacuum to one atmosphere pressure. The heat transfer characteristics of the reactors are reported in detail. It is assumed the experimental results are to form the basis of a devolatilization data base. Empirical rate expressions are developed for each phase of devolatilization which, when coupled to an awareness of the heat transfer rate potential of a particular devolatilization reactor, indicate the kinetics emphasized by a particular system reactor plus coal sample. The analysis indicates the particular phase of devolatilization that will be emphasized by a particular reactor type and, thereby, the kinetic expressions appropriate to that devolatilization system. Engineering rate expressions are developed from the empirical rate expressions in the context of a fundamental understanding of coal devolatilization developed in the course of the investigation. 164 refs., 223 figs., 44 tabs.

Intrinsic reaction kinetics of coal char combustion by direct measurement of ignition temperature

International Nuclear Information System (INIS)

Kim, Ryang-Gyoon; Jeon, Chung-Hwan

2014-01-01

A wire heating reactor that can use a synchronized experimental method was developed to obtain the intrinsic kinetics of large coal char particles ranging in size from 0.4 to 1 mm. This synchronization system consists of three parts: a thermocouple wire for both heating and direct measurement of the particle temperature, a photodetector sensor for determining ignition/burnout points by measuring the intensity of luminous emission from burning particles, and a high-speed camera–long-distance microscope for observing and recording the movement of luminous zone directly. Coal char ignition was found to begin at a spot on the particle's external surface and then moved across the entire particle. Moreover, the ignition point determined according to the minimum of dT/dt is a spot point and not a full growth point. The ignition temperature of the spot point rises as the particle diameter increases. A spot ignition model, which describes the ignition in terms of the internal conduction and external/internal oxygen diffusion, was then developed to evaluate the intrinsic kinetics and predict the ignition temperature of the coal char. Internal conduction was found to be important in large coal char particles because its effect becomes greater than that of oxygen diffusion as the particle diameter increases. In addition, the intrinsic kinetics of coal char obtained from the spot ignition model for two types of coal does not differ significantly from the results of previous investigators. -- Highlights: • A novel technique was used to measure the coal char particle temperature. • The ignition point determined from a dT/dt minimum is a spot ignition point. • A spot ignition model was suggested to analyze the intrinsic reaction kinetics of coal char. • Internal conduction has to be considered in order to evaluate the intrinsic kinetics for larger particle (above 1 mm)

Effect of Mineral Filler Type and Particle Size on the Engineering Properties of Stone Mastic Asphalt Pavements

Directory of Open Access Journals (Sweden)

R Muniandy

2013-12-01

Full Text Available This study examines four types of industrial and by-product waste fillers, namely limestone dust (LSD, which was the reference filler; ceramic waste dust (CWD; coal fly ash (CFA, and steel slag mixture (SSD. The filler consisted of an aggregate (10% of total weight with three proportions: 100% passing 75μm, 50% passing 75μm/20μm, and 100% passing 20μm. Comprehensive laboratory tests were performed to determine the impact of different types and particle sizes of fillers on the engineering and mechanical properties of fine mastics and stone mastic asphalt mixture. The results indicate that the application of industrial by-products used as fillers improves the engineering properties of stone mastic asphalt mixtures. The increased stiffness due to the addition of the filler is represented by an increase in the softening point, viscosity, stability, and resilient modulus, as well as a decrease in penetration. The optimum asphalt content increased with the decrease in filler particle size for LSD and SSD, and decreased for CWD and CFA. It was also determined that the filler type and particle size has a significant effect on the mixture properties. Among these three proportions, the samples prepared with the filler size proportion of 50/50 gave the best value in terms of stability, Marshall quotient, and resilient modulus than the other filler size proportions.

Cleaning and dewatering fine coal

Science.gov (United States)

Yoon, Roe-Hoan; Eraydin, Mert K.; Freeland, Chad

2017-10-17

Fine coal is cleaned of its mineral matter impurities and dewatered by mixing the aqueous slurry containing both with a hydrophobic liquid, subjecting the mixture to a phase separation. The resulting hydrophobic liquid phase contains coal particles free of surface moisture and droplets of water stabilized by coal particles, while the aqueous phase contains the mineral matter. By separating the entrained water droplets from the coal particles mechanically, a clean coal product of substantially reduced mineral matter and moisture contents is obtained. The spent hydrophobic liquid is separated from the clean coal product and recycled. The process can also be used to separate one type of hydrophilic particles from another by selectively hydrophobizing one.

Correcting for particle size effects on plasma actuator particle image velocimetry measurements

Science.gov (United States)

Masati, A.; Sedwick, R. J.

2018-01-01

Particle image velocimetry (PIV) is often used to characterize plasma actuator flow, but particle charging effects are rarely taken into account. A parametric study was conducted to determine the effects of particle size on the velocity results of plasma actuator PIV experiments. Results showed that smaller particles more closely match air flow velocities than larger particles. The measurement uncertainty was quantified by deconvolving the particle image diameter from the correlation diameter. The true air velocity was calculated by linearly extrapolating to the zero-size particle diameter.

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.

Rheology of Victorian brown coal slurries

Energy Technology Data Exchange (ETDEWEB)

Woskoboenko, F.; Siemon, S.R.; Creasy, D.E.

1987-09-01

Aqueous suspensions of finely ground raw brown coal from Victoria, Australia, have been tested in a Couette viscometer to evaluate their rheological properties. Shear rates covered the range 1-800s/sup -1/ and median particles were 6-41 ..mu..m. Concentrations up to 0.6 volume fraction were examined. The results were well represented by the two parameter Bingham model. It was found that the degree of non-Newtonian behaviour, as measured by yield stress, increased as the concentration was increased or the particle size decreased. The yield stress can be directly related to the volumetric solids concentration, particle size distribution and external specific area via a single, physically meaningful parameter - the mean distance separating the particles. The power law relationship between yield stress and inter-particle distance can be used to gauge the degree of flocculation of the system. As with non-interacting particle systems, the plastic viscosity of these suspensions increases in a logarithmic fashion as the concentration increases but is independent of the absolute particle size. 35 refs., 5 figs., 2 tabs.

In Vitro Toxicity of Naturally Occurring Silica Nanoparticles in C1 Coal 
in Bronchial Epithelial Cells

Directory of Open Access Journals (Sweden)

Guangjian LI

2012-10-01

Full Text Available Background and objective China’s Xuan Wei County in Yunnan Province have the world’s highest incidence of lung cancer in nonsmoking women-20 times higher than the rest of China. Previous studies showed, this high lung cancer incidence may be associated with the silica particles embedded in the production combustion from the C1 coal. The aim of this study is to separate the silica particles from production combustion from the C1 bituminous coal in Xuan Wei County of Yunnan Province, and study in vitro toxicity of naturally occurring silica particles on BEAS-2B. Methods ①Separating the silica particles from combustion products of C1 bituminous coal by physical method, observing the morphology by Scanning Electron Microscope, analysis elements by SEM-EDX, observed the single particle morphology by Transmission Electron Microscope, analyed its particle size distribution by Laser particle size analyzer, the surface area of silica particles were determined by BET nitrogen adsorption analysis; ②Cell viability of the experimental group (silica; naturally occurring, control group (silica; industrial produced and crystalline silica was detected by assay used the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT method, and the reactive oxygen species (ROS, lactate dehydrogenase (LDH were determined after 24 h-72 h exposed to these particles. Results ①The physical method can separate silica particles from production combustion from the C1 bituminous coal, which have different size, and from 30 nm to 120 nm particles accounted for 86.8%, different morphology, irregular surface area and containing trace of aluminum, calcium and iron and other elements; ②Under the same concentration, the experiment group have higher toxicity on BEAS-2B than control groups. Conclusion ①Physical method can separate silica particles from production combustion from the C1 bituminous coal and not change the original morphology and containing trace; �

Vibro-spring particle size distribution analyser

International Nuclear Information System (INIS)

Patel, Ketan Shantilal

2002-01-01

This thesis describes the design and development of an automated pre-production particle size distribution analyser for particles in the 20 - 2000 μm size range. This work is follow up to the vibro-spring particle sizer reported by Shaeri. In its most basic form, the instrument comprises a horizontally held closed coil helical spring that is partly filled with the test powder and sinusoidally vibrated in the transverse direction. Particle size distribution data are obtained by stretching the spring to known lengths and measuring the mass of the powder discharged from the spring's coils. The size of the particles on the other hand is determined from the spring 'intercoil' distance. The instrument developed by Shaeri had limited use due to its inability to measure sample mass directly. For the device reported here, modifications are made to the original configurations to establish means of direct sample mass measurement. The feasibility of techniques for measuring the mass of powder retained within the spring are investigated in detail. Initially, the measurement of mass is executed in-situ from the vibration characteristics based on the spring's first harmonic resonant frequency. This method is often erratic and unreliable due to the particle-particle-spring wall interactions and the spring bending. An much more successful alternative is found from a more complicated arrangement in which the spring forms part of a stiff cantilever system pivoted along its main axis. Here, the sample mass is determined in the 'static mode' by monitoring the cantilever beam's deflection following the wanton termination of vibration. The system performance has been optimised through the variations of the mechanical design of the key components and the operating procedure as well as taking into account the effect of changes in the ambient temperature on the system's response. The thesis also describes the design and development of the ancillary mechanisms. These include the pneumatic

Particle sizes from sectional data

DEFF Research Database (Denmark)

Pawlas, Zbynek; Nyengaard, Jens Randel; Jensen, Eva Bjørn Vedel

2009-01-01

We propose a new statistical method for obtaining information about particle size distributions from sectional data without specific assumptions about particle shape. The method utilizes recent advances in local stereology. We show how to estimate separately from sectional data the variance due t...

Method for processing coal-enrichment waste with solid and volatile fuel inclusions

Science.gov (United States)

Khasanova, A. V.; Zhirgalova, T. B.; Osintsev, K. V.

2017-10-01

The method relates to the field of industrial heat and power engineering. It can be used in coal preparation plants for processing coal waste. This new way is realized to produce a loose ash residue directed to the production of silicate products and fuel gas in rotary kilns. The proposed method is associated with industrial processing of brown coal beneficiation waste. Waste is obtained by flotation separation of rock particles up to 13 mm in size from coal particles. They have in their composition both solid and volatile fuel inclusions (components). Due to the high humidity and significant rock content, low heat of combustion, these wastes are not used on energy boilers, they are stored in dumps polluting the environment.

SAMPLING, ANALYSIS, AND PROPERTIES OF PRIMARY PM-2.5: APPLICATION TO COAL-FIRED UTILITY BOILERS

Energy Technology Data Exchange (ETDEWEB)

Allen L. Robinson; Spyros N. Pandis; Eric Lipsky; Charles Stainer; Natalie Anderson; Satoshi Takahama; Sarah Rees

2003-02-01

A dilution sampler was used to examine the effects of dilution ratio and residence time on the particulate emissions from a pilot-scale pulverized coal combustor. Measurements include the particle size distribution from 0.003 to 2.5 {micro}m, PM{sub 2.5} mass emission rate and PM2.5 composition (OC/EC, major ions, and elemental). Hot filter samples were also collected simultaneously in order to compare the dilution sampler measurement with standard stack sampling methodologies such as EPA Method 5. Measurements were made both before and after the bag-house, the particle control device used on the coal combustor. Measurements were made with three different coal types and a coal-biomass blend. The residence time and dilution ratio do not influence the PM{sub 2.5} mass emission rate, but have a significant effect on the size distribution and total number emissions. Measurements made before the bag-house showed increasing the residence time dramatically decreases the total particle number concentration, and shifts the particle mass to larger sizes. The effects of residence time can be explained quantitatively by the coagulation of the emitted particles. Measurements made after the bag-house were not affected by coagulation due to the lower concentration of particles. Nucleation of sulfuric acid vapor within the dilution was an important source of ultrafine particles. This nucleation is strongly a function of dilution ratio because of the competition between condensation and nucleation. At low dilution ratios condensation dominates and little nucleation is observed; increasing the dilution ratio promotes nucleation because of the corresponding decrease in available surface area per unit volume for condensation. No nucleation was observed after the bag house where conditions greatly favor nucleation over condensation; we suspect that the bag house removed the SO{sub 3} in the flue gas. Exhaust SO{sub 3} levels were not measured during these experiments. Dilution caused

Burnout of pulverized biomass particles in large scale boiler – Single particle model approach

DEFF Research Database (Denmark)

Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero

2010-01-01

the particle combustion model is coupled with one-dimensional equation of motion of the particle, is applied for the calculation of the burnout in the boiler. The particle size of biomass can be much larger than that of coal to reach complete burnout due to lower density and greater reactivity. The burner...... location and the trajectories of the particles might be optimised to maximise the residence time and burnout....

Ignition of a floating droplet of organic coal-water fuel

Science.gov (United States)

Nakoryakov, V. E.; Kuznetsov, G. V.; Strizhak, P. A.

2016-06-01

The results of experimental investigations are presented for the ignition of droplets (particles) of organic coal-water fuels (OCWFs) floating in a flow of an oxidizer using a special combustion chamber from high-temperature quartz glass. The temperature and the velocity of motion of the oxidizer vary in the ranges of 500-900 K and 0.5-3 m/s. The initial sizes (radii) of fuel droplets amounted to 0.3-1.5 mm. As the basic OCWF components, particles (of 80-100 µm in size) of brown coal "B2," water, mazut, and waste castor and compressor oils are used. With use of the system of high-velocity video registration, the conditions providing for floating of OCWF particles without initiation of burning and with the subsequent steady ignition are established. Four modes of OCWF-droplet ignition with different trajectories of their motion in the combustion chamber are singled out. The times of the OCWF-ignition delay in dependence on the size of fuel particles and oxidizer temperatures are determined. The deviations of the OCWF-ignition-delay times obtained under conditions of suspension of a droplet on the thermocouple junction and while floating in the oxidizer flow are established.

Pyrometric fuel particle measurements in pressurised reactors

Energy Technology Data Exchange (ETDEWEB)

Hernberg, R; Joutsenoja, T [Tampere Univ. of Technology (Finland)

1997-10-01

A fibre-optic two-colour pyrometric technique for fuel particle temperature and size measurement is modified and applied to three pressurised reactors of different type in Finland, Germany and France. A modification of the pyrometric method for simultaneous in situ measurement of the temperature and size of individual pulverised coal particles at the pressurised entrained flow reactor of VTT Energy in Jyvaeskylae was developed and several series of measurements were made in order to study the effects of oxygen concentration (3-30 vol%) and pressure (0.2-1.0 MPa) on the particle temperature. The fuels used in the experiments were Westerholt, Polish and Goettelborn hvb coals, Gardanne lignite and Niederberg anthracite. The initial nominal fuel particle size varied in the experiments from 70 to 250 ,{mu}m and the gas temperature was typically 1173 K. For the anthracite also the effects of gas temperature (1073-1423K) and CO{sub 2} concentration (6-80 vol%) were studied. In Orleans a fibreoptic pyrometric device was installed to a pressurised thermogravimetric reactor of CNRS and the two-colour temperatures of fuel samples were measured. The fuel in the experiments was pulverised Goettelborn char. The reliability of optical temperature measurement in this particular application was analysed. In Essen a fibre-optic pyrometric technique that is capable to measure bed and fuel particle temperatures was applied to an atmospheric fluidised bed reactor of DMT. The effects of oxygen concentration (3-8 vol%) and bed temperature (1123-1193 K) on the fuel particle temperature were studied. The fuels in these were Westerholt coal and char and EBV-coal. Some results of these measurements are presented. The project belonged to EU`s Joule 2 extension research programme (contract JOU2-CT93-0331). (orig.)

Experimental studies on the group ignition of a cloud of coal particles: Volume 2, Pyrolysis and ignition modeling

Energy Technology Data Exchange (ETDEWEB)

Annamalai, K.; Ryan, W.

1992-01-01

The primary objectives of this work are to formulate a model to simulate transient coal pyrolysis, ignition, and combustion of a cloud of coal particles and to compare results of the program with those reported in the literature elsewhere.

Ultraviolet (UV) disinfection of grey water: particle size effects.

Science.gov (United States)

Winward, G P; Avery, L M; Stephenson, T; Jefferson, B

2008-02-01

The impact of water quality on the ultraviolet (UV) disinfection of grey water was investigated with reference to urban water reuse. Direct UV disinfection of grey water did not meet the stringent California State Title 22 criteria for unrestricted urban water reuse due to the presence of particulate material ranging from or = 2000 microm in size. Grey water was manipulated by settling to produce fractions of varying particle size distributions and blending was employed post-disinfection to extract particle-associated coliforms (PACs). The efficacy of UV disinfection was found to be linked to the particle size of the grey water fractions. The larger particle size fractions with a mean particle size of 262 microm and above were observed to shield more coliforms from UV light than did the smaller particles with a mean particle size below 119 microm. Up to 70% of total coliforms in the larger particle size fractions were particle-associated following a UV dose (fluence) of 260 mJ.cm(-2) and would remain undetected by standard coliform enumeration techniques. Implications for urban water reuse are discussed and recommendations made for grey water treatment to ensure removal of particle-associated indicator bacteria and pathogens prior to UV disinfection.

REMOVAL OF TRICHLOROACETIC ACID FROM THE AQUEOUS SOLUTIONS USING NATURAL AND ACTIVATED LIGNITE COALS

Directory of Open Access Journals (Sweden)

Hüseyin GÜLENSOY

1998-02-01

Full Text Available In these studies, a typical lignite coal found near Istanbul (Yeniköy and its activated products were used to adsorb TCA from aqueous solutions. Particle sizes of coal samples and the concentrations of TCA solutions were chosen as parameters against the fixed amount of adsorbent. The maximum efficiency has been obtained for the coal having (-120 + 150 mesh size fraction activated by heating. As a result, it was shown that these kinds of lignite coals could be used as a good adsorbent. In addition, it was also proved that both the removal and recovery of TCA from some waste waters would easily be possible.

Concentration and size distribution of particles in abstracted groundwater.

Science.gov (United States)

van Beek, C G E M; de Zwart, A H; Balemans, M; Kooiman, J W; van Rosmalen, C; Timmer, H; Vandersluys, J; Stuyfzand, P J

2010-02-01

Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of larger particles. However, the particle concentration in groundwater derived from abstraction wells, with high groundwater flow velocities, is much lower than in groundwater from monitor wells, with minimal flow velocities. This inconsistency points to exhaustion of the particle supply in the aquifer around wells due to groundwater abstraction for many years. The particle size distribution can be described with the help of a power law or Pareto distribution. Comparing the measured particle size distribution with the Pareto distribution shows that particles with a diameter >7 microm are under-represented. As the particle size distribution is dependent on the flow velocity, so is the value of the "Pareto" slope beta. (c) 2009 Elsevier Ltd. All rights reserved.

Application of a validated gasification model to determine the impact of coal particle grinding size on carbon conversion

KAUST Repository

Kumar, Mayank; Ghoniem, Ahmed F.

2013-01-01

In this paper, we describe the implementation of a comprehensive, previously validated multiscale model of entrained flow gasification to examine the impact of particle size on the gasification process in two different gasifier designs; the MHI and the GE gasifier. We show that the impact of the particle size depends on whether the char conversion process is kinetically limited or boundary layer diffusion-limited. Fine grinding helps accelerate char conversion under diffusion-control conditions, whereas the impact is not as noticeable under kinetic-control operation. The availability of particular gasification agents, namely O2 in the earlier sections of the gasifier or CO2 and H2O in the latter sections, as well as the temperature, are shown to have an impact on the relative importance of kinetics versus diffusion limitation. © 2013 Elsevier Ltd. All rights reserved.

Application of a validated gasification model to determine the impact of coal particle grinding size on carbon conversion

KAUST Repository

Kumar, Mayank

2013-06-01

In this paper, we describe the implementation of a comprehensive, previously validated multiscale model of entrained flow gasification to examine the impact of particle size on the gasification process in two different gasifier designs; the MHI and the GE gasifier. We show that the impact of the particle size depends on whether the char conversion process is kinetically limited or boundary layer diffusion-limited. Fine grinding helps accelerate char conversion under diffusion-control conditions, whereas the impact is not as noticeable under kinetic-control operation. The availability of particular gasification agents, namely O2 in the earlier sections of the gasifier or CO2 and H2O in the latter sections, as well as the temperature, are shown to have an impact on the relative importance of kinetics versus diffusion limitation. © 2013 Elsevier Ltd. All rights reserved.

EFFECTS OF EFFECTS OF PARTICLE SIZE DISTRIBUTION ...

African Journals Online (AJOL)

eobe

The parameters examined were: moisture content, particle size distribution, total isture content, particle size distribution, total hydrocarbon content, soil pH, available nitrogen, available phosphorus, total heterotrophic bacteria and fungi count. The analysis of the soil characteristics throughout the remediation period showed ...

Particulate behavior in a controlled-profile pulverized coal-fired reactor: A study of coupled turbulent particle dispersion and thermal radiation transport. Final technical progress report

Energy Technology Data Exchange (ETDEWEB)

Queiroz, M.; Webb, B.W.

1996-06-01

To aid in the evaluation and development of advanced coal-combustion models, comprehensive experimental data sets are needed containing information on both the condensed and gas phases. To address this need a series of test were initiated on a 300 kW laboratory-scale, coal-fired reactor at a single test condition using several types of instrumentation. Data collected on the reactor during the course of the test includes: gas, particle, and wall temperature profiles; radiant, total, and convective heat fluxes to the walls; particle size and velocity profiles; transmission measurements; and gas species concentrations. Solid sampling was also performed to determine carbon and total burnout. Along with the extensive experimental measurements, the particle dispersion and radiation submodels in the ACERC comprehensive 2D code were studied in detail and compared to past experimental measurements taken in the CPR. In addition to the presentation and discussion of the experimental data set, a detailed description of the measurement techniques used in collecting the data, including a discussion of the error associated with each type of measurement, is given.

Dependence of strength on particle size in graphite

International Nuclear Information System (INIS)

Kennedy, E.P.; Kennedy, C.R.

The strength to particle size relationship for specially fabricated graphites has been demonstrated and rationalized using fracture mechanics. In the past, similar studies have yielded empirical data using only commercially available material. Thus, experimental verification of these relationships has been difficult. However, the graphites of this study were fabricated by controlling the particle size ranges for a series of isotropic graphites. All graphites that were evaluated had a constant 1.85 g/cm 3 density. Thus, particle size was the only variable. This study also considered the particle size effect on other physical properties; coefficient of thermal expansion (CTE), electrical resistivity, fracture strain, and Young's modulus

Formation and filtration of flocs from coal slurries

Energy Technology Data Exchange (ETDEWEB)

Singh, B K

1977-06-01

The size and size distribution of flocs are greatly influenced by the type and concentration of the flocculant coal and dirt particles behave differently in this respect. The pH and the concentration of electrolytes also influence flocculation, by changing both the surface properties of the solid material and the effectiveness of the flocculant. The relationship between the sedimentation time and the filtration rate depends on the concentration and type of flocculant. Optimum pH values for various conditions are tabulated. When an anion-active flocculant is added to a coal-dirt mixture in an alkaline medium, selective flocculation occurs; this can be used to improve the separation of slurries.

Modeling of the flame propagation in coal-dust- methane air mixture in an enclosed sphere volume

International Nuclear Information System (INIS)

Krainov, A Yu; Moiseeva, K M

2016-01-01

The results of the numerical simulation of the flame front propagation in coal-dust- methane-air mixture in an enclosed volume with the ignition source in the center of the volume are presented. The mathematical model is based on a dual-velocity two-phase model of the reacting gas-dispersion medium. The system of equations includes the mass-conversation equation, the impulse-conversation equation, the total energy-conversation equation of the gas and particles taking into account the thermal conductivity and chemical reactions in the gas and on the particle surface, mass-conversation equation of the mixture gas components considering the diffusion and the burn-out and the particle burn-out equation. The influence of the coal particle mass on the pressure in the volume after the mixture burn out and on the burn-out time has been investigated. It has been shown that the burning rate of the coal-dust methane air mixtures depends on the coal particle size. (paper)

Examination of flame length for burning pulverized coal in laminar flow reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae Dong; Kim, Gyu Bo; Chang, Young June; Song, Ju Hun; Jeon, Chung Hwan [Pusan National University, Busan (Korea, Republic of)

2010-12-15

Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model

Examination of flame length for burning pulverized coal in laminar flow reactor

International Nuclear Information System (INIS)

Kim, Jae Dong; Kim, Gyu Bo; Chang, Young June; Song, Ju Hun; Jeon, Chung Hwan

2010-01-01

Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model

Combustion of pulverized coal in counter-current flow

Energy Technology Data Exchange (ETDEWEB)

Timnat, Y M; Goldman, Y [Technion-Israel Inst. of Tech., Haifa (Israel). Faculty of Aerospace Engineering

1991-01-01

In this report we describe the results obtained with two prototypes of pulverized coal combustors operating in counter-current flow, one at atmospheric pressure, the other at higher pressure and compare them to the predictions of a theoretical-numerical model, we have developed. The first prototype treats a vertical configuration, eight times larger than the one treated before (Hazanov et al. 1985), while in the second a horizontal arrangement with a smaller volume is studied. Attention was focused on particle trajectories, burnout, angle of injection, ash separation by rotational motion, effects of initial particle size and temperature, impingement velocity and the effect of gravity. Main development activity was directed to achieving stable and reliable coal burning in the combustors.

Trace element emissions from coal

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-09-15

Trace elements are emitted during coal combustion. The quantity, in general, depends on the physical and chemical properties of the element itself, the concentration of the element in the coal, the combustion conditions and the type of particulate control device used, and its collection efficiency as a function of particle size. Some trace elements become concentrated in certain particle streams following combustion such as bottom ash, fly ash, and flue gas particulate matter, while others do not. Various classification schemes have been developed to describe this partitioning behaviour. These classification schemes generally distinguish between: Class 1: elements that are approximately equally concentrated in the fly ash and bottom ash, or show little or no fine particle enrichment, examples include Mn, Be, Co and Cr; Class 2: elements that are enriched in the fly ash relative to bottom ash, or show increasing enrichment with decreasing particle size, examples include As, Cd, Pb and Sb; Class 3: elements which are emitted in the gas phase (primarily Hg (not discussed in this review), and in some cases, Se). Control of class 1 trace elements is directly related to control of total particulate matter emissions, while control of the class 2 elements depends on collection of fine particulates. Due to the variability in particulate control device efficiencies, emission rates of these elements can vary substantially. The volatility of class 3 elements means that particulate controls have only a limited impact on the emissions of these elements.

Investigations concerning the mechanism of action of brown-coal coke particles in aerobic biological waste water treatment

International Nuclear Information System (INIS)

Rieger, W.

1990-01-01

At the start of this work experience with the use of brown coal coke in the activated sludge process was lacking entirely. It therefore was necessary to carry through preliminary experiments in order to practically test the effect of Grown-coal coke. In two technical-scale experiments and a pilot test, very good results were obtained with the application of brown-coal coke to activated sludge. These, and previously published results, permitted to evolve moodel concepts of the mechanism of action of coal, especially brown coal coke, in activated sludge. According to these concepts the coal particles act as buffers and a temporary adsorbent of oxygen and waste water constituents. This in turn stimulates the colonization of the surface with microorganisms. In order to corroborate these model concepts, the - adsorption and desorption of solved oxygen to coal in a watery medium and - the effect of coal over a longer period of time were investigated. The results in essence confirm the model concepts. (UWa) [de

Sonochemical synthesis of silica particles and their size control

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

2016-09-01

Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

Occurrence of trace elements in respirable coal dust

International Nuclear Information System (INIS)

Sahoo, B.N.

1991-01-01

Inhalation of fine particles of coal dust contributes significantly to the occurrence of the disease, pneumoconiosis, prevailing in coal mining community. It is not presently known whether only the coal dust or specific chemical compounds or synergistic effects of several compounds associated with respirable coal dust is responsible for the disease, pneumoconiosis. The present paper describes the quantitative determination of ten minor and trace elements in respirable coal dust particles by atomic absorption spectrophotometric methods. The respirable coal dust samples are collected at the mine atmosphere during drilling in coal scams by using Messrs. Casella's Hexlet apparatus specially designed and fitted with horizontal elutriator to collect the respirable coal dust fraction simulating as near as possible to the lung's retention of the coal miners. After destruction of organic matter by wet oxidation and filtering off clay and silica, Fe, Ca, Mg, Na, K, Mn, Cu, Zn, Cd, and Ni were determined directly in the resulting solution by atomic absorption spectrophotometric procedures. The results show that the trace metals are more acute in lower range of size spectrum. Correlation coefficient, enrichment factor and linear regression values and their inverse relationship between the slope and EF values suggest that, in general, the trace metals in respirable particulates are likely to be from coal derived source if their concentrations are likewise high in the coal. The trace metal analytical data of respirable particulates fitted well to the linear regressive equation. The results of the studies are of importance as it may throw some light on the respirable lung disease 'pneumoconiosis' which are predominant in coal mining community. (author). 13 refs., 6 tabs

Reduced emissions from inexpensive high-sulphur coal briquettes

International Nuclear Information System (INIS)

Gammage, R.B.; Wachter, E.A.; Wade, J.; Wilson, D.L.; Haas, J.W.; Ahmad, N.; Siltain, F.; Raza, M.Z.

1992-01-01

Airborne emissions were measured during the combustion of Pakistani high-sulphur coal, cold briquetted with lime and clay; comparison was made to emissions from raw coal and traditional fuels burnt in a native, mud-lined Angethi stove. Compared to raw coal, the amended coal gave fourfold reduced emission of respirable-size particles (RSP) and threefold reduced total releases of SO 2 . In domestic cooking, substitution of the amended coal briquettes for traditional fuels will not worsen indoor air quality with respect to CO, SO 2 , NO x , and RSP. The high peak amounts of CO (100--250 ppm), SO 2 (2--5 ppm), and NO x (1--5 ppm) were limited to the early phase of burning. The high thermal value of the coal briquettes together with a simple briquetting technology, make this fuel an attractive energy alternative in countries that are underdeveloped, developing, or experiencing major restructuring

Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

Science.gov (United States)

Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

2013-12-01

We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

Incipient motion of gravel and coal beds

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

2. 1Department of Civil Engineering, Indian Institute of Technology, ... the particle size distribution curve following the relationship by Christensen .... where f = friction factor, ρ = mass density of fluid, and V = mean velocity of flow. .... for the incipient motion of gravel and coal beds have been represented by simple empirical.

Relationship between polycyclic aromatic hydrocarbons (PAHs) and particle size in dated core sediments in Lake Lianhuan, Northeast China

Energy Technology Data Exchange (ETDEWEB)

Sun, Li; Zang, Shuying, E-mail: zsy6311@163.com

2013-09-01

Atmospheric particle associated with pyrogenic polycyclic aromatic hydrocarbons (PAHs) poses serious threats to human health by inhalation exposure, especially in semiarid areas. Hence, the distributions of PAHs and particle size in two core sediments collected from Lake Lianhuan, Northeast China were studied. The sediments were dated radiometrically, and particle size distribution and PAH concentration were evaluated and potential human health risk was assessed. From 1980 to 2007, the dominant PAHs in the two cores were 2- and 3-ring PAHs, and the concentrations of 3–6 ring PAHs gradually increased from the early 1990s. Diagnostic ratios indicated that pyrogenic PAHs were the main sources of PAHs which changed over time from combustions of wood and coal to liquid fossil fuel sources. Fine particles (< 65 μm) were the predominant particle size (56–97%). Lacustrine source (with the peak towards 200–400 μm) and eolian sources derived from short (2.0–10 and 30–65 μm) and long (0.4–1.0 μm) distance suspension were indentified from frequency distribution pattern of particle size. Significant correlations between 3–6 ring PAHs (especially carcinogenic 5–6 ring PAHs) and 10–35 μm particulate fractions indicated that eolian particles played an important role in adsorbing pyrogenic PAHs. Petroleum source of PAHs was only identified during the 1980s in one core sediments, in which positive correlations between 2-ring PAHs and particulate fractions of > 125 μm were found. Future research should focus on the seven carcinogenic pyrogenic PAHs due to a rapidly increasing trend since 1995 based on the assessment of toxic equivalency factors. - Highlights: • PAHs and particle size in core sediments were used to evaluate the role of eolian particles in delivering pyrogenic PAHs. • Changes of PAH sources closely followed local historical socioeconomic development since 1980s. • Changes of particulate sources from eolian to lacustrine reflected the

Suppression of coffee ring: (Particle) size matters

Science.gov (United States)

Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

2018-05-01

Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

Directory of Open Access Journals (Sweden)

Gang Zhou

2016-01-01

Full Text Available Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Electrochemistry of carbonaceous materials. 3. Reactivity of redox couples with coal slurries in 85% phosphoric acid media

Energy Technology Data Exchange (ETDEWEB)

Tomat, R.; Salmaso, R.; Zecchin, S. [CNR - Istituto di Polarografia ed Elettrochimica Preparativa, Padova (Italy)

1994-02-01

Sardinian subbituminous coal slurries were oxidized in 85% H{sub 3}PO{sub 4} by metal ions (Ce{sup 4+}, V{sup 5+}, V{sup 4+}, Mn{sup 3+} and Fe{sup 3+}) and the effects of metal ion concentration, coal content of slurry, coal particle size and temperature were examined. 19 refs., 3 figs., 2 tabs.

Characterization and supply of coal-based fuels. Quarterly report, February 1, 1989--April 30, 1989

Energy Technology Data Exchange (ETDEWEB)

1989-06-01

Contract objectives are as follows: Develop fuel specifications to serve combustor requirements. Select coals having appropriate compositional and quality characteristics as well as an economically attractive reserve base; Provide quality assurance for both the parent coals and the fuel forms; and deliver premium coal-based fuels to combustor developers as needed for their contract work. Progress is discussed, particulary in slurry fuel preparation and particle size distribution.

EFFECTS OF ULTRASOUND ON THE MORPHOLOGY, PARTICLE SIZE, CRYSTALLINITY, AND CRYSTALLITE SIZE OF CELLULOSE

Directory of Open Access Journals (Sweden)

SUMARI SUMARI

2014-05-01

Full Text Available The aim of this study is to optimize ultrasound treatment to produce fragment of cellulose that is low in particles size, crystallite size, and crystallinity. Slurry of 1 % (w/v the cellulose was sonicated at different time periods and temperatures. An ultrasonic reactor was operated at 300 Watts and 28 kHz to cut down the polymer into smaller particles. We proved that ultrasound damages and fragments the cellulose particles into shorter fibers. The fiber lengths were reduced from in the range of 80-120 µm to 30-50 µm due to an hour ultrasonication and became 20-30 µm after 5 hours. It was also found some signs of erosion on the surface and stringy. The acoustic cavitation also generated a decrease in particle size, crystallinity, and crystallite size of the cellulose along with increasing sonication time but it did not change d-spacing. However, the highest reduction of particle size, crystallite size, and crystallinity of the cellulose occurred within the first hour of ultrasonication, after which the efficiency was decreased. The particle diameter, crystallite size, and crystallinity were decreased from 19.88 µm to 15.96 µm, 5.81 Å to 2.98 Å, and 77.7% to 73.9% respectively due to an hour ultrasound treatment at 40 °C. The treatment that was conducted at 40 °C or 60 °C did not give a different effect significantly. Cellulose with a smaller particle and crystallite size as well as a more amorphous shape is preferred for further study.

Gasification Characteristics of Coal/Biomass Mixed Fuels

Energy Technology Data Exchange (ETDEWEB)

Mitchell, Reginald [Stanford Univ., CA (United States). Mechanical Engineering Dept.

2014-09-01

pores and energy exchange between the particle and its environment. This char-particle gasification model is capable of predicting the average mass loss rates, sizes, apparent densities, specific surface areas, and temperatures of the char particles produced when co-firing coal and biomass to the type environments established in entrained flow gasifiers operating at high temperatures and elevated pressures.

Permeability of different size waste particles

Directory of Open Access Journals (Sweden)

Sabina Gavelytė

2015-10-01

Full Text Available The world and life style is changing, but the most popular disposal route for waste is landfill globally until now. We have to think about waste prevention and preparing for re-use or recycling firstly, according to the waste disposal hierarchy. Disposed waste to the landfill must be the last opportunity. In a landfill, during waste degradation processes leachate is formed that can potentially cause clogging of bottom drainage layers. To ensure stability of a landfill construction, the physical properties of its components have to be controlled. The hydrology of precipitation, evaporation, runoff and the hydraulic performance of the capping and liner materials are important controls of the moisture content. The water balance depends also on the waste characteristics and waste particle size distribution. The aim of this paper is to determine the hydraulic permeability in a landfill depending on the particle size distribution of municipal solid waste disposed. The lab experiment results were compared with the results calculated with DEGAS model. Samples were taken from a landfill operated for five years. The samples particle sizes are: >100 mm, 80 mm, 60 mm, 40 mm, 20 mm, 0.01 mm and <0.01 mm. The permeability test was conducted using the column test. The paper presents the results of experiment and DEGAS model water permeability with waste particle size.

Effect of silica particle size on macrophage inflammatory responses.

Directory of Open Access Journals (Sweden)

Toshimasa Kusaka

Full Text Available Amorphous silica particles, such as nanoparticles (<100 nm diameter particles, are used in a wide variety of products, including pharmaceuticals, paints, cosmetics, and food. Nevertheless, the immunotoxicity of these particles and the relationship between silica particle size and pro-inflammatory activity are not fully understood. In this study, we addressed the relationship between the size of amorphous silica (particle dose, diameter, number, and surface area and the inflammatory activity (macrophage phagocytosis, inflammasome activation, IL-1β secretion, cell death and lung inflammation. Irrespective of diameter size, silica particles were efficiently internalized by mouse bone marrow-derived macrophages via an actin cytoskeleton-dependent pathway, and induced caspase-1, but not caspase-11, activation. Of note, 30 nm-1000 nm diameter silica particles induced lysosomal destabilization, cell death, and IL-1β secretion at markedly higher levels than did 3000 nm-10000 nm silica particles. Consistent with in vitro results, intra-tracheal administration of 30 nm silica particles into mice caused more severe lung inflammation than that of 3000 nm silica particles, as assessed by measurement of pro-inflammatory cytokines and neutrophil infiltration in bronchoalveolar lavage fluid of mice, and by the micro-computed tomography analysis. Taken together, these results suggest that silica particle size impacts immune responses, with submicron amorphous silica particles inducing higher inflammatory responses than silica particles over 1000 nm in size, which is ascribed not only to their ability to induce caspase-1 activation but also to their cytotoxicity.

Test installation for studying erosion-corrosion of metals for coal washing plants

Energy Technology Data Exchange (ETDEWEB)

Hoey, G. R.; Dingley, W.; Wiles, C. T.

1979-02-15

A test installation was constructed for investigating erosion-corrosion of metals by coal-water slurries. Erosion-corrosion tests of mild steel panels were conducted using slurries of alundum, quartz, washed coal and coal refuse. Wear rates were found to depend on type of abrasive, particle size and water conductivity and were reduced by cathodic protection and inhibitors. Cathodic protection of mild steel in coal slurries containing sulphate ion reduced wear by 90% and 86% for stationary and rotating panels, respectively. This study has demonstrated that the successful application of corrosion control techniques would reduce metal wastage in coal washing plants. The test installation is considered suitable for developing the techniques.

Thermal Behavior of Coal Used in Rotary Kiln and Its Combustion Intensification

Directory of Open Access Journals (Sweden)

Qiang Zhong

2018-04-01

Full Text Available Pyrolysis and combustion behaviors of three coals (A, B, and C coals were investigated and their combustion kinetics were calculated by the Freeman–Carroll method to obtain quantitative insight into their combustion behaviors. Moreover, the effects of coal size, air flow, oxygen content, and heating rate on coal combustion behaviors were analyzed. Results showed that the three coals have a similar trend of pyrolysis that occurs at about 670 K and this process continuously proceeds along with their combustion. Combustion characteristics and kinetic parameters can be applied to analyze coal combustion behaviors. Three coals having combustion characteristics of suitable ignition temperature (745–761 K, DTGmax (14.20–15.72%/min, and burnout time (7.45–8.10 min were analyzed in a rotary kiln. Combustion kinetic parameters provide quantitative insights into coal combustion behavior. The suitable particle size for coal combustion in a kiln is that the content of less than 74 μm is 60% to 80%. Low activation energy and reaction order make coal, especially C coal, have a simple combustion mechanism, great reactivity, be easily ignited, and a low peak temperature in the combustion state. Oxygen-enrichment and high heating rates enhance coal combustion, increasing combustion intensity and peak value, thus shortening burnout time.

Artificial neural network based particle size prediction of polymeric nanoparticles.

Science.gov (United States)

Youshia, John; Ali, Mohamed Ehab; Lamprecht, Alf

2017-10-01

Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificial neural network including these properties as input with particle size and polydispersity index as output. The established model successfully predicted particle size of nanoparticles covering a range of 70-400nm prepared from other polymers. The percentage bias for particle prediction was 2%, 4% and 6%, for the training, validation and testing data, respectively. Polymer surface activity was found to have the highest impact on the particle size followed by viscosity and finally hydrophobicity. Results of this study successfully highlighted polymer properties affecting particle size and confirmed the usefulness of artificial neural networks in predicting the particle size and polydispersity of polymeric nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

The Rheology of a Three Component System: COAL/WATER/#4 Oil Emulsions.

Science.gov (United States)

Gilmartin, Barbara Jean

The purpose of this investigation was to study the rheology of a three component system, coal/water/#4 oil emulsions (COW), in which the third component, water, was present in a significant concentration, and to determine the applicability of existing theories from suspension rheology to the three component system studied. In a coal/water/oil emulsion, free coal particles adhere to the surface of the water droplets, preventing their coagulation, while the larger coal particles reside in the matrix of stabilized water droplets. The use of liquid fuels containing coal is a means of utilizing our nation's coal reserves while conserving oil. These fuels can be burned in conventional oil-fired furnaces. In this investigation, a high sulfur, high ash, bituminous coal was used, along with a heavy #4 oil to prepare the emulsions. The coal was ground to a log-normal distribution with an average particle size of 62 microns. A Haake RV3 concentric cylinder viscometer, with a ribbed measuring system, was used to determine the viscosity of the emulsions. A physical pendulum settling device measured the shift in center of mass of the COW as a function of time. The flow behavior of the fuel in pipes was also tested. In interpreting the data from the viscometer and the pipe flow experiments, a power law analysis was used in the region from 30 s('-1) to 200 s('-1). Extrapolation methods were used to obtain the low and high shear behavior of the emulsions. In the shear rate region found in boiler feed systems, COW are shear thinning with a flow behavior index of 0.7. The temperature dependent characteristic of the emulsions studied were similar and followed an Arrhenius type relationship. The viscosity of the COW decreases with increasing coal average particle size and is also a function of the width of the size distribution used. The type of coal used strongly influences the rheology of the fuel. The volatile content and the atomic oxygen to nitrogen ratio of the coal are the most

Distribution Of Natural Radioactivity On Soil Size Particles

International Nuclear Information System (INIS)

Tran Van Luyen; Trinh Hoai Vinh; Thai Khac Dinh

2008-01-01

This report presents a distribution of natural radioactivity on different soil size particles, taken from one soil profile. On the results shows a range from 52% to 66% of natural radioisotopes such as 238 U, 232 Th, 226 Ra and 40 K concentrated on the soil particles below 40 micrometers in diameter size. The remained of natural radioisotopes were distributed on a soil particles with higher diameter size. The study is available for soil sample collected to natural radioactive analyze by gamma and alpha spectrometer methods. (author)

Flat-flame burner studies of pulverized-coal combustion. Experimental results on char reactivity

Energy Technology Data Exchange (ETDEWEB)

Peck, R.E.; Shi, L.

1996-12-01

Structure of laminar, premixed pulverized-coal flames in a 1-D reactor has been studied with emphasis on char reactivity. A 1.1-meter-long tube furnace accommodated high-temperature environments and long residence times for the laminar flames produced by a flat-flame, coal-dust burner. Experiments were conducted at different operating conditions (fuel type/size, fuel-air ratio). Measurements included solid sample composition, major gas species and hydrocarbon species concentrations, and gas- and particle-phase line-of-sight temperatures at different axial locations in flames. Degree of char burnout increased with coal volatiles content and decreased with coal particle size. Combustion in furnace was in oxidizer-deficient environment and higher burnout was achieved as the fuel-air ratio neared stoichiometric. For 0-45 {mu}m particles most of the fixed carbon mass loss occurred within 5 cm of the furnace inlet, and char reaction was slow downstream due to low oxidizer concentrations. Fixed carbon consumption of the 45-90 {mu}m particles generally was slower than for the small particles. About 40%-80% of the fixed carbon was oxidized in the furnace. Primary volatiles mass loss occurred within the first 4.5 cm, and more than 90% of the volatiles were consumed in the flames. The flames stabilized in the furnace produced less CH{sub 4} and H{sub 2} in the burnt gas than similar unconfined flames. NO concentrations were found to decrease along the furnace and to increase with decreasing fuel/air ratio. Temperature measurement results showed that gas-phase temperatures were higher than solid-phase temperatures. Temperatures generally decreased with decreasing volatiles content and increased as the equivalence ratio approached one. The results can be used to interpret thermochemical processes occurring in pulverized-coal combustion. (au) 15 refs.

Detection of Coal Fires: A Case Study Conducted on Indian Coal Seams Using Neural Network and Particle Swarm Optimization

Science.gov (United States)

Singh, B. B.

2016-12-01

India produces majority of its electricity from coal but a huge quantity of coal burns every day due to coal fires and also poses a threat to the environment as severe pollutants. In the present study we had demonstrated the usage of Neural Network based approach with an integrated Particle Swarm Optimization (PSO) inversion technique. The Self Potential (SP) data set is used for the early detection of coal fires. The study was conducted over the East Basuria colliery, Jharia Coal Field, Jharkhand, India. The causative source was modelled as an inclined sheet like anomaly and the synthetic data was generated. Neural Network scheme consists of an input layer, hidden layers and an output layer. The input layer corresponds to the SP data and the output layer is the estimated depth of the coal fire. A synthetic dataset was modelled with some of the known parameters such as depth, conductivity, inclination angle, half width etc. associated with causative body and gives a very low misfit error of 0.0032%. Therefore, the method was found accurate in predicting the depth of the source body. The technique was applied to the real data set and the model was trained until a very good correlation of determination `R2' value of 0.98 is obtained. The depth of the source body was found to be 12.34m with a misfit error percentage of 0.242%. The inversion results were compared with the lithologs obtained from a nearby well which corresponds to the L3 coal seam. The depth of the coal fire had exactly matched with the half width of the anomaly which suggests that the fire is widely spread. The inclination angle of the anomaly was 135.510 which resembles the development of the geometrically complex fracture planes. These fractures may be developed due to anisotropic weakness of the ground which acts as passage for the air. As a result coal fires spreads along these fracture planes. The results obtained from the Neural Network was compared with PSO inversion results and were found in

Determination of reactivity rates of silicate particle-size fractions

Directory of Open Access Journals (Sweden)

Angélica Cristina Fernandes Deus

2014-04-01

Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

Modeling and experiments for the time-dependent diffusion coefficient during methane desorption from coal

Science.gov (United States)

Cheng-Wu, Li; Hong-Lai, Xue; Cheng, Guan; Wen-biao, Liu

2018-04-01

Statistical analysis shows that in the coal matrix, the diffusion coefficient for methane is time-varying, and its integral satisfies the formula μt κ /(1 + β κ ). Therefore, a so-called dynamic diffusion coefficient model (DDC model) is developed. To verify the suitability and accuracy of the DDC model, a series of gas diffusion experiments were conducted using coal particles of different sizes. The results show that the experimental data can be accurately described by the DDC and bidisperse models, but the fit to the DDC model is slightly better. For all coal samples, as time increases, the effective diffusion coefficient first shows a sudden drop, followed by a gradual decrease before stabilizing at longer times. The effective diffusion coefficient has a negative relationship with the size of the coal particle. Finally, the relationship between the constants of the DDC model and the effective diffusion coefficient is discussed. The constant α (μ/R 2 ) denotes the effective coefficient at the initial time, and the constants κ and β control the attenuation characteristic of the effective diffusion coefficient.

Experimental research on combustion fluorine retention using calcium-based sorbents during coal combustion (II)

Energy Technology Data Exchange (ETDEWEB)

Qi, Q.; Ma, X.; Liu, J.; Wu, X.; Zhou, J.; Cen, K. [Liaoning Technical University, Fuxin (China). College of Resource and Environment Engineering

2008-12-15

Fluoride pollution produced by coal burning can be controlled with the calcium-based sorbent combustion fluorine technique in which calcium-based sorbents are mixed with the coal or sprayed into the combustion chamber. In a fixed bed tube furnace combustion experiment using one calcium-based natural mineral, limestone and one calcium-based building material, it was shown that the calcium-based sorbent particle grain size and pore structure have a big influence on the combustion fluorine retention effect. Reducing the calcium-based sorbent particle grain size and improving the calcium sorbent structure characteristics at very high temperature to enhance the fluorine retention effect is the important approach to the fluorine retention agent development. 8 refs., 1 fig., 5 tabs.

Size-resolved fluxes of sub-100-nm particles over forests

DEFF Research Database (Denmark)

Pryor, Sara; Barthelmie, Rebecca Jane; Spaulding, A.M.

2009-01-01

Dry deposition of atmospheric particles is critically dependent on particle size and plays a key role in dictating the mass and number distributions of atmospheric particles. However, modeling dry deposition is constrained by a lack of understanding of controlling dependencies and accurate size......-resolved observations. We present size-resolved particle number fluxes for sub-100-nm particle diameters (Dp) over a deciduous forest derived using eddy covariance applied to data from a fast mobility particle sizer. The size-resolved particle number fluxes in 18 diameters between 8 and 100 nm were collected during...... leaf-on and are statistically robust. Particle deposition velocities normalized by friction velocity (v d +) are approximately four times smaller than comparable values for coniferous forests reported elsewhere. Comparison of the data with output from a new one-dimensional mechanistic particle...

Effect of particle size on iron nanoparticle oxidation state

International Nuclear Information System (INIS)

Lombardo, Jeffrey J.; Lysaght, Andrew C.; Goberman, Daniel G.; Chiu, Wilson K.S.

2012-01-01

Selecting catalyst particles is a very important part of carbon nanotube growth, although the properties of these nanoscale particles are unclear. In this article iron nanoparticles are analyzed through the use of atomic force microscopy and x-ray photoelectron spectroscopy in order to understand how the size affects the chemical composition of nanoparticles and thus their physical structure. Initially, atomic force microscopy was used to confirm the presence of iron particles, and to determine the average size of the particles. Next an analytical model was developed to estimate particle size as a function of deposition time using inputs from atomic force microscopy measurement. X-ray photoelectron spectroscopy analysis was then performed with a focus on the spectra relating to the 2p Fe electrons to study the chemical state of the particles as a function of time. It was shown that as the size of nanoparticles decreased, the oxidation state of the particles changed due to a high proportion of atoms on the surface.

Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles

Energy Technology Data Exchange (ETDEWEB)

Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States). Dept. of Mechanical Engineering

2013-06-30

One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed

Particle size control of detergents in mixed flow spray dryers

Directory of Open Access Journals (Sweden)

Mark Jonathan Crosby

2015-03-01

Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

EFFECT OF MICROWAVE DRYING ON THE GRINDABILITY OF LIGNITE COAL

OpenAIRE

Güngören, Can; Özkan, Şafak Gökhan; Hacıfazlıoğlu, Hasan

2016-01-01

In this study, the representative lignite coal samples supplied from Kastamonu-Tosya region were dried in a conventional drying oven and a microwave oven, and then they were ground by a laboratory rod mill. The particle size analyses of the ground samples at various grinding times (10, 20, 30, and 60 minutes) were carried out, and the results were compared. As a result, the d80 particle sizes of the samples, dried in the conventional drying oven, were determined as 350, 183, 180, and 100 µm a...

A study on the char burnout characteristics of coal and biomass blends

Energy Technology Data Exchange (ETDEWEB)

Behdad Moghtaderi [University of Newcastle, Callaghan, NSW (Australia). Discipline of Chemical Engineering, School of Engineering, Faculty of Engineering and Built Environment

2007-10-15

The char burnout characteristics of coal/biomass blends under conditions pertinent to pulverised fuel combustors were investigated by a combined modelling and experimental approach. Results indicate that blending of coal with biomass increases the likelihood of char extinction (i.e. extinction potential of the char particle in the blend), in turn, decreasing the char burnout level. Our modelling results attribute this to a reduction in the char particle size to levels below a critical dimension which appears to be a strong function of the fuel blending ratio (the weight percentage of biomass in the blend), fuel reactivity, char cloud shape and particle density number. It is demonstrated here that the drop in the char burnout level during co-firing can be effectively resolved when a more reactive secondary coal is added to the blend to minimise its extinction potential. 22 refs., 8 figs., 2 tabs.

Intercomparison of 15 Aerodynamic Particle Size Spectrometers (APS 3321): Uncertainties in Particle Sizing and Number Size Distribution.

Czech Academy of Sciences Publication Activity Database

Pfeifer, S.; Müller, T.; Weinhold, K.; Zíková, Naděžda; dos Santos, S.M.; Marinoni, A.; Bischof, O.F.; Kykal, C.; Ries, L.; Meinhardt, F.; Aalto, P.; Mihalopoulos, N.; Wiedensohler, A.

2016-01-01

Roč. 9, č. 4 (2016), s. 1545-1551 ISSN 1867-1381 EU Projects: European Commission(XE) 262254 - ACTRIS Institutional support: RVO:67985858 Keywords : counting efficiency * aerodynamic particle size spectrometers * laboratory study Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.089, year: 2016

Using BIB-SEM to determine pore morphology and pore size distributions in coal macerals

Energy Technology Data Exchange (ETDEWEB)

Giffin, S.; Littke, R. [RWTH Aachen Univ. (Germany). Inst. of Geology and Geochemistry of Petroleum and Coal; Klaver, J.; Urai, J.L. [RWTH Aachen Univ. (Germany). Structural Geology, Tectonics and Geomechanics

2013-08-01

The composition of coalbeds is considerably heterogeneous, affecting the transport pathways for fluids within the coal. Transport pathways include cleats and larger pores. However, only a few clues exist as the nature of these pores. This study examines the morphology and distribution of macro- and mesopores in coal samples, using broad ion beam (BIB) milling to prepare relief- and damage-free polished surfaces of coal samples for high-resolution SEM imaging. Broad ion beam milling is advantageous to focused ion beam milling in that a larger surface area can be milled. Combining that with SEM imaging results in a useful tool to study pore morphology and distributions in the size range between 10 nm and 10 {mu}m. Since BIB-sections of a few square millimeters are not large enough to be statistically representative, results cannot be easily interpreted from a coal seam standpoint. Therefore, porosity was investigated as a function of maceral type to characterize pore morphologies. Macerals from the vitrinite and inertinite groups were selected with a known relationship to bedding. BIB-sections were milled parallel to bedding and perpendicular to bedding, and the pores were evaluated in each section. The goal of this study is to (1) qualitatively describe pore morphology with respect to maceral type and (2) quantitatively characterize pore size distributions with respect to maceral and in relationship to bedding. Our results lead to a better understanding of bulk coal porosity due to the visual, spatial representation and quantification of pores in individual macerals. (orig.)

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.

Remote Laser Diffraction Particle Size Distribution Analyzer

Energy Technology Data Exchange (ETDEWEB)

Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael

2001-03-01

In support of a radioactive slurry sampling and physical characterization task, an “off-the-shelf” laser diffraction (classical light scattering) particle size analyzer was utilized for remote particle size distribution (PSD) analysis. Spent nuclear fuel was previously reprocessed at the Idaho Nuclear Technology and Engineering Center (INTEC—formerly recognized as the Idaho Chemical Processing Plant) which is on DOE’s INEEL site. The acidic, radioactive aqueous raffinate streams from these processes were transferred to 300,000 gallon stainless steel storage vessels located in the INTEC Tank Farm area. Due to the transfer piping configuration in these vessels, complete removal of the liquid can not be achieved. Consequently, a “heel” slurry remains at the bottom of an “emptied” vessel. Particle size distribution characterization of the settled solids in this remaining heel slurry, as well as suspended solids in the tank liquid, is the goal of this remote PSD analyzer task. A Horiba Instruments Inc. Model LA-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a “hot cell” (gamma radiation) environment. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not previously achievable—making this technology far superior than the traditional methods used. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.

Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks

Directory of Open Access Journals (Sweden)

C. R. Santos

Full Text Available Commercial coal production in the southern region of Brazil has been occurring since the beginning of the twentieth century. Due to the geological characteristics of the region, large amounts of solid wastes are generated. The aim of this work was to evaluate the use of coal waste to produce concrete paving blocks. A procedure to process the coal waste with the purpose of reducing the sulfur content and changing the particle size distribution of the material to meet the specification of fine aggregates was developed. The methodology considered the following steps: (a sampling of a coal mining waste; (b gravity separation of the fraction with specific gravity between 2.4 and 2.8; (c comminution of the material and particle size analysis; (d technological characterization of the material and production of concrete paving blocks; and (e acidity generation prediction (environmental feasibility. The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks in a proportion of up to 50%. This practice can result in cleaner coal production and reduce the demand for exploitation of sand deposits.

Initiator Systems Effect on Particle Coagulation and Particle Size Distribution in One-Step Emulsion Polymerization of Styrene

Directory of Open Access Journals (Sweden)

Baijun Liu

2016-02-01

Full Text Available Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.

Particle interaction of lubricated or unlubricated binary mixtures according to their particle size and densification mechanism.

Science.gov (United States)

Di Martino, Piera; Joiris, Etienne; Martelli, Sante

2004-09-01

The aim of this study is to assess an experimental approach for technological development of a direct compression formulation. A simple formula was considered composed by an active ingredient, a diluent and a lubricant. The active ingredient and diluent were selected as an example according to their typical densification mechanism: the nitrofurantoine, a fragmenting material, and the cellulose microcrystalline (Vivapur), which is a typical visco-elastic material, equally displaying good bind and disintegrant properties. For each ingredient, samples of different particle size distribution were selected. Initially, tabletability of pure materials was studied by a rotary press without magnesium stearate. Vivapur tabletability decreases with increase in particle size. The addition of magnesium stearate as lubricant decreases tabletability of Vivapur of greater particle size, while it kept unmodified that of Vivapur of lower particle size. Differences in tabletability can be related to differences in particle-particle interactions; for Vivapur of higher particle size (Vivapur 200, 102 and 101), the lower surface area develops lower surface available for bonds, while for Vivapur of lower particle size (99 and 105) the greater surface area allows high particle proximity favouring particle cohesivity. Nitrofurantoine shows great differences in compression behaviour according to its particle size distribution. Large crystals show poorer tabletability than fine crystals, further decreased by lubricant addition. The large crystals poor tabletability is due to their poor compactibility, in spite of high compressibility and plastic intrinsic deformability; in fact, in spite of the high densification tendency, the nature of the involved bonds is very weak. Nitrofurantoine samples were then mixed with Vivapurs in different proportions. Compression behaviour of binary mixes (tabletability and compressibility) was then evaluated according to diluents proportion in the mixes. The

Determining size-specific emission factors for environmental tobacco smoke particles

Energy Technology Data Exchange (ETDEWEB)

Klepeis, Neil E.; Apte, Michael G.; Gundel, Lara A.; Sextro, Richard G.; Nazaroff, William W.

2002-07-07

Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured every minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1-2+ micrometer diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01-1+ micrometer diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m{sup 3} chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 hours after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle emission factors were fit with log-normal distributions, yielding an average mass median diameter of 0.2 micrometers and an average geometric standard deviation of 2.3 with no systematic differences between cigars and cigarettes. The equivalent total particle emission rate, obtained integrating each size distribution, was 0.2-0.7 mg/min for cigars and 0.7-0.9 mg/min for cigarettes.

Particle sizes in slash fire smoke.

Science.gov (United States)

David V. Sandberg; Robert E. Martin

1975-01-01

Particulate emissions are the most objectionable atmospheric contaminant from forest burning. Little is known of the particulate sizes, and this research was done under laboratory conditions to obtain particle size information. Comments are made concerning techniques for future work in this field.

MICRON-SIZED POLYMER PARTICLES FROM TANZANIAN ...

African Journals Online (AJOL)

Micron sized polymeric particles were prepared from cashew nut shell liquid and subsequently functionalized to produce micron-sized carboxylated cation exchange resin (MCCER). By titrimetry and analytical procedures employing atomic absorption spectrometry, an assessment of the cation exchange capability of the ...

Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

Directory of Open Access Journals (Sweden)

A. Wiedensohler

2012-03-01

Full Text Available Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers or SMPS (Scanning Mobility Particle Sizers have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the

Particle size- and concentration-dependent separation of magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Witte, Kerstin, E-mail: witte@micromod.de [University of Rostock, Institute of Physics, Albert-Einstein-Str. 23, 18059 Rostock (Germany); Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Müller, Knut; Grüttner, Cordula; Westphal, Fritz [Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Johansson, Christer [Acreo Swedish ICT AB, 40014 Göteborg (Sweden)

2017-04-01

Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations. - Highlights: • Size dependent separation processes of multicore nanoparticles. • Concentration dependent separation processes of multicore nanoparticles. • Increasing separation time with rising concentrations for small particles. • Large particles show typical cooperative magnetophoresis behavior.

Effect of reaction temperature on the PM10 features during coal combustion

International Nuclear Information System (INIS)

Sui, J.C.; Du, Y.G.; Liu, Q.C.

2008-01-01

Coal-fired power plants produce fine fly ash consisting of particulate matter (PM). Particulate matter less than 10 micrometers in aerodynamic diameter (PM 1 0) is of significant concern because of its adverse environmental and health impacts. This paper studied the effect of reaction temperature on particulate matter (PM 1 0) emission and its chemical composition. The emission characteristics and elemental partition of PM 1 0 from coal combustion were investigated in a drop tube furnace. The paper discussed the experimental apparatus and conditions as well as the coal properties and sample analysis. Liupanshui (LPS) bituminous coal from China was used for the study. The fuel composition of LPS coal and the composition of low temperature ash of Chinese LPS coal were described. The paper also presented the results of the study with reference to particle size distribution and emission characteristic of PM 1 0; elemental partition within PM 1 0; and effect of the reaction temperature on elemental partition within PM 1 0. The PM mass size distribution was found to be bimodal. 14 refs., 2 tabs., 6 figs

A system for aerodynamically sizing ultrafine environmental radioactive particles

International Nuclear Information System (INIS)

Olawoyin, L.

1995-09-01

The unattached environmental radioactive particles/clusters, produced mainly by 222 Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It's major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented

A system for aerodynamically sizing ultrafine environmental radioactive particles

Energy Technology Data Exchange (ETDEWEB)

Olawoyin, L.

1995-09-01

The unattached environmental radioactive particles/clusters, produced mainly by {sup 222}Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It`s major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented.

Effects of intraparticle heat and mass transfer during devolatilization of a single coal particle

NARCIS (Netherlands)

Bliek, A.; Poelje, W.M.; van Swaaij, Willibrordus Petrus Maria; van Beckum, F.P.H.

1985-01-01

The objective of the present work is to elucidate the influence of intraparticle mass and heat transfer phenomena on the overall rate and product yields during devolatilization of a single coal particle in an inert atmosphere. To this end a mathematical model has been formulated which covers

Tailoring particle size and morphology of colloidal Ag particles via chemical precipitation for Ag-BSCCO composites

International Nuclear Information System (INIS)

Medendorp, N.W. Jr.; Bowman, K.J.; Trumble, K.P.

1996-01-01

The chemical precipitation of silver particles is an effective method for tailoring the particle size and morphology. This article investigates a chemical precipitation method for producing silver colloids, and how processing parameters affected particle size, morphology and adherence. Decreasing the silver nitrate concentration during precipitation with sodium borohydride decreased the colloidal silver particle size. Decreasing the addition rate of the reducing agent produced faceted particles. Reversing the reactant addition order also changed the particle size and the morphology. Precipitated colloids demonstrated a difference between the growth-dominated and the equilibrium structures. Co-dispersing Bi-based superconducting platelets during precipitation allowed Ag colloids to preferentially nucleate on the platelets and to remain adhered even after the additional processing. (orig.)

Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium

Science.gov (United States)

Zakhari, Monica E. A.; Anderson, Patrick D.; Hütter, Markus

2017-07-01

Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012), 10.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1 % . The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

A study of particle size distribution in zirconia-alumina powders

International Nuclear Information System (INIS)

Ramakrishnan, K.N.; Venkadesan, S.; Nagarajan, R.

1996-01-01

Powder particles, in general are characterized in terms of particle size, size distributions and composition for reasons associated with manufacturing problem based upon product quality, manufacturing convenience, cost and product handling convenience. Particle size analysis or the measurement of particle size distribution is a common effort in any physical, chemical or mechanical processes. This information and processing methods are intricate factors that relate to material behavior and/or physical properties of the fabricated product. The requirements for the formation of a product of particulate solids and its strength varies as the particle size and the size distribution changes. Also the transport properties and the chemical activity are related to the particle size and the size distribution. The choice of a distribution to represent a physical system is generally motivated by an understanding of the nature of underlying phenomenon and is verified by the available data. After a model has been chosen, its parameter must be determined. The reasonableness of a selected model on the basis of given data is especially important when the model is to be used for prediction. Two different approaches in this problem are probability plotting and statistical tests

Coal pyrolysis and char burnout under conventional and oxy-fuel conditions

Energy Technology Data Exchange (ETDEWEB)

Al-Makhadmeh, L.; Maier, J.; Scheffknecht, G. [Stuttgart Univ. (Germany). Institut fuer Verfahrenstechnik und Dampfkesselwesen

2009-07-01

Coal utilization processes such as combustion or gasification generally involve several steps i.e., the devolatilization of organic materials, homogeneous reactions of volatile matter with the reactant gases, and heterogeneous reactions of the solid (char) with the reactant gases. Most of the reported work about coal pyrolysis and char burnout were performed at low temperatures under environmental conditions related to the air firing process with single particle tests. In this work, coal combustion under oxy-fuel conditions is investigated by studying coal pyrolysis and char combustion separately in practical scales, with the emphasis on improving the understanding of the effect of a CO{sub 2}-rich gas environment on coal pyrolysis and char burnout. Two coals, Klein Kopje a medium volatile bituminous coal and a low-rank coal, Lausitz coal were used. Coal pyrolysis in CO{sub 2} and N{sub 2} environments were performed for both coals at different temperatures in an entrained flow reactor. Overall mass release, pyrolysis gas concentrations, and char characterization were performed. For char characterization ultimate analysis, particle size, and BET surface area were measured. Chars for both coals were collected at 1150 C in both CO{sub 2} and N{sub 2} environments. Char combustion was performed in a once-through 20 kW test facility in O{sub 2}/CO{sub 2} and O{sub 2}/N{sub 2} atmospheres. Besides coal quality, oxygen partial pressure was chosen as a variable to study the effect of the gas environment on char burnout. In general, it is found that the CO{sub 2} environment and coal rank have a significant effect on coal pyrolysis and char burnout. (orig.)

Ultrafine coal classification using 150 mm gMax cyclone circuits

Energy Technology Data Exchange (ETDEWEB)

Honaker, R.Q.; Boaten, F.; Luttrell, G.H. [University of Kentucky, Lexington, KY (United States). Dept. of Mineral Engineering

2007-11-15

A two-stage classification circuit using 150 mm diameter gMax cyclones was installed and evaluated in a coal preparation plant in an effort to achieve a clean coal product without the use of froth flotation. Particle size separations of around 37 {mu}m were achieved while limiting ultrafine bypass to less than 10% in the circuit underflow stream. As a result, approximately 81% of the ash-bearing material in the circuit feed was rejected to the circuit overflow stream. The feed ash content was reduced from around 50% to values in the range of 22-30% in the circuit underflow stream with a mass recovery of about 30%. Further reductions in the coarse product ash content were limited due to the particle density effect and the remaining presence of a significant quantity of high-ash slime material in the coarse product. The typical D{sub 50} for the coal particles was 40 {mu} m while the estimated value for mineral matter was 17 {mu} m. Based on the findings of the study, the use of classification to recover a low-ash, coarse fraction in the feed of a fine coal circuit is limited by the density effect regardless of the ability to eliminate ultrafine bypass.

HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

Energy Technology Data Exchange (ETDEWEB)

Stefano Orsino

2005-03-30

As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two series of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical

Flotation process diagnostics and modelling by coal grain analysis

Energy Technology Data Exchange (ETDEWEB)

Ofori, P; O' Brien, G.; Firth, B.; Jenkins, B. [CSIRO Energy Technology, Brisbane, Qld. (Australia)

2006-05-15

In coal flotation, particles of different components of the coal such as maceral groups and mineral matter and their associations have different hydrophobicities and therefore different flotation responses. By using a new coal grain analysis method for characterising individual grains, more detailed flotation performance analysis and modelling approaches have been developed. The method involves the use of microscopic imaging techniques to obtain estimates of size, compositional and density information on individual grains of fine coal. The density and composition partitioning of coal processed through different flotation systems provides an avenue to pinpoint the actual cause of poor process performance so that corrective action may be initiated. The information on grain size, density and composition is being used as input data to develop more detailed flotation process models to provide better predictions of process performance for both mechanical and column flotation devices. A number of approaches may be taken to flotation modelling such as the probability approach and the kinetic model approach or a combination of the two. In the work reported here, a simple probability approach has been taken, which will be further refined in due course. The use of grain data to map the responses of different types of coal grains through various fine coal cleaning processes provided a more advanced diagnostic capability for fine coal cleaning circuits. This enabled flotation performance curves analogous to partition curves for density separators to be produced for flotation devices.

Characterization of the impregnated iron based catalyst for direct coal liquefaction by EXAFS

International Nuclear Information System (INIS)

Yang Jianli; Zhun Jisheng; Liu Zhenyu; Zhong Bing

2002-01-01

Catalyst plays an important role in direct coal liquefaction (DCL). Iron catalysts are regarded as the most attractive catalysts for DCL. To maximize catalytic effect and minimize catalysts usage, ultra-fine size catalysts are preferred. The most effective catalysts are found to be those impregnated onto coal because of their high dispersion on coal surface and intimate contact with coal particles. Besides the physical size, chemical form of a catalyst or a catalyst precursor is also important in determination of DCL activity. The expended X-ray absorption fine structure spectroscopy technique were used in this study. It was shown that the catalysts tested are in nanomater range and have structure mainly in the form of γ-FeOOH and FeS, or possibly of Fe/O/S. The presence of γ-FeOOH can be attributed to the interaction between Fe and the oxygen containing groups of coal or oxygen from moisture

Particle size dependence of biogenic secondary organic aerosol molecular composition

Science.gov (United States)

Tu, Peijun; Johnston, Murray V.

2017-06-01

Formation of secondary organic aerosol (SOA) is initiated by the oxidation of volatile organic compounds (VOCs) in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process) to be distinguished from those produced by particle phase reaction (a volume-limited process). In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O / C) ratio and carbon oxidation state (OSc) were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases). Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased), the average O / C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes important.

Particle size dependence of biogenic secondary organic aerosol molecular composition

Directory of Open Access Journals (Sweden)

P. Tu

2017-06-01

Full Text Available Formation of secondary organic aerosol (SOA is initiated by the oxidation of volatile organic compounds (VOCs in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process to be distinguished from those produced by particle phase reaction (a volume-limited process. In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O ∕ C ratio and carbon oxidation state (OSc were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases. Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased, the average O ∕ C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes

Production of sized particles of uranium oxides and uranium oxyfluorides

International Nuclear Information System (INIS)

Knudsen, I.E.; Randall, C.C.

1976-01-01

A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

Fundamental study for improvement of dewatering of fine coal/refuse. Final report, August 1981-December 1984

Energy Technology Data Exchange (ETDEWEB)

Chiang, S.H.; Klinzing, G.E.; Morsi, B.I.; Tierney, J.W.; Binkley, T.; Chi, S.M.; Huang, S.; Qamar, I.; Venkatadri, R.

1984-12-01

Fine coal in slurry form must be dewatered to minimize handling and transportation problems and be reduced to a desirable level for subsequent preparation of coal/water mixtures as a substitute utility fuel. The current practice is inadequate for the dewatering of fine coal, particularly for coal particles with sizes smaller than 400 mesh. Therefore, it is most desirable to develop improved mechanical methods for reducing the moisture content of fine coal. In the light of this, a fundamental study of the dewatering of fine coal/refuse was initiated in June 1979 and continued through 1984. The overall objective of the study is to seek improved methods of dewatering through a better understanding of the filtration and post-filtration processes. As a first step, efforts have been focused on the mechanism of dewatering in terms of the basic properties of coal (and refuse) particles and the microstructures of filter cakes, and their relations to filtration rate and final moisture content. Pittsburgh seam-Bruceton Mine coal was used as a base coal. During the past year, filter cakes from coals with widely varying size ranges were micrographically characterized. The effects of a number of surface active agents and of entrapped air bubbles on the filter cake properties were also studied. Modules of the network model for calculating single phase and two phase permeabilities were formulated and tested. The report is divided into four parts: summary and deliverables; work forecast for 1984-1985; detailed description of technical progress; and appendices. 21 refs., 55 figs., 17 tabs.

Thermogravimetric analytical procedures for characterizing New Zealand and eastern Australian coals

Energy Technology Data Exchange (ETDEWEB)

Benfell, K.E.; Beamish, B.B.; Rodgers, K.A. [University of Auckland, Auckland (New Zealand). Dept. of Geology

1996-09-01

Under tightly constrained experimental conditions (particle size {lt}75 {mu}m, sample mass 5.0 {+-} 0.5 mg), heating rate 15{degree}C min{sup -1}, dry air purge 50 mL min{sup -1}, maximum temperature 900{degree}C a repeatability of {lt} {+-} 2{degree}C, may be achieved for significant temperatures that characterize the differential thermogravimetric burning profiles of typical medium-volatile, bituminous Australian Gondwanan coals and high-volatile, bituminous New Zealand Cretaceous-Tertiary coals.

Selection Of Suitable Particle Size And Particle Ratio For Japanese Cucumber Cucumis Sativus L. Plants

Directory of Open Access Journals (Sweden)

Galahitigama GAH

2015-08-01

Full Text Available This study was conducted to select the best particle size of coco peat for cucumber nurseries as well as best particle ratio for optimum plant growth and development of cucumber. The experiment was carried out in International Foodstuff Company and Faculty of Agriculture University of Ruhuna Sri Lanka during 2015 to 2016. Under experiment one three types of different particle sizes were used namely fine amp88040.5mm T2 medium 3mm-0.5mm T3 and coarse 4mm T4 with normal coco peat T1 as treatments. Complete Randomized Design CRD used as experimental design with five replicates. Germination percentage number of leaves per seedling seedling height in frequent day intervals was taken as growth parameters. Analysis of variance procedure was applied to analyze the data at 5 probability level. The results revealed that medium size particle media sieve size 0.5mm -3mm of coco peat was the best particle size for cucumber nursery practice when considered the physical and chemical properties of medium particles of coco peat. In the experiment of selecting of suitable particle ratio for cucumber plants the compressed mixture of coco peat particles that contain 70 ww unsieved coco peat 20 ww coarse particles and 10 ww coconut husk chips 5 12mm has given best results for growth performances compared to other treatments and cucumber grown in this mixture has shown maximum growth and yield performances.

Reactivity of mechanical activated coals for special utilization

Energy Technology Data Exchange (ETDEWEB)

Turcaniova, L.; Kadarova, J.; Imrich, P.; Liptaj, T.; Vidlar, J.; Vasek, J.; Foldyna, F.; Sitek, J.; Balaz, P. [Slovak Academy of Science, Kosice (Slovakia). Inst. of Geotechnology

2004-09-01

The paper presents the coal activation effect as disintegration in the nano-submicron range and destruction carbon structure. The Slovak brown coal activated in planetary mill is characterised by destruction of organic structure of coal. The biggest activation effect connected with the destruction of C-C bonds of sp{sup 3} carbons has been confirmed by {sup 13}C NMR spectroscopy in the chemical structure of humic acids extracted from the coal sample activated for a period of 60 min. The specific surface of humic acids is much smaller then that of mechanically activated sample from which they were extracted. The black Czech coal was activated by two stage disintegration. In the first stage of mechanochemical activation using Grinding Aqueous Caustic Leaching, GACL method, a fine dispersed semiproduct is formed with the size of particles from 2.5 to 9000 nm. The additional disintegration using water jet increases the effect of disintegration in the submicron area of the coal product. The volume distribution maximum achieves in this stage about 60 wt% of 750 nm grains.

Effect of Prussian blue on organic sulfur of coal in aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Demirbas, A. [Selcuk University, Konya (Turkey). Dept. of Chemical Engineering

2007-01-15

This study is an attempt to desulfurize organic sulfur from coal samples with ferric hexacyanoferrate (II), Fe{sub 4} (Fe(CN){sub 6}), as the desulfurization agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the level of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K. The organic sulfur removal rate sharply increases from 10 min to 30 min stirring time. After 30 min, it reaches a value of plateau. Particle size between -100 mesh and -200 mesh slightly affects the amount of organic sulfur removal. Gradual increase in the concentration of ferric hexacyanoferrate (II) raised the magnitude of desulfurization, but at higher concentration, the variation is not significant.

Estimating particle number size distributions from multi-instrument observations with Kalman Filtering

Energy Technology Data Exchange (ETDEWEB)

Viskari, T.

2012-07-01

Atmospheric aerosol particles have several important effects on the environment and human society. The exact impact of aerosol particles is largely determined by their particle size distributions. However, no single instrument is able to measure the whole range of the particle size distribution. Estimating a particle size distribution from multiple simultaneous measurements remains a challenge in aerosol physical research. Current methods to combine different measurements require assumptions concerning the overlapping measurement ranges and have difficulties in accounting for measurement uncertainties. In this thesis, Extended Kalman Filter (EKF) is presented as a promising method to estimate particle number size distributions from multiple simultaneous measurements. The particle number size distribution estimated by EKF includes information from prior particle number size distributions as propagated by a dynamical model and is based on the reliabilities of the applied information sources. Known physical processes and dynamically evolving error covariances constrain the estimate both over time and particle size. The method was tested with measurements from Differential Mobility Particle Sizer (DMPS), Aerodynamic Particle Sizer (APS) and nephelometer. The particle number concentration was chosen as the state of interest. The initial EKF implementation presented here includes simplifications, yet the results are positive and the estimate successfully incorporated information from the chosen instruments. For particle sizes smaller than 4 micrometers, the estimate fits the available measurements and smooths the particle number size distribution over both time and particle diameter. The estimate has difficulties with particles larger than 4 micrometers due to issues with both measurements and the dynamical model in that particle size range. The EKF implementation appears to reduce the impact of measurement noise on the estimate, but has a delayed reaction to sudden

Effect of particle size on mixing degree in dispensation.

Science.gov (United States)

Nakamura, Hitoshi; Yanagihara, Yoshitsugu; Sekiguchi, Hiroko; Ohtani, Michiteru; Kariya, Satoru; Uchino, Katsuyoshi; Suzuki, Hiroshi; Iga, Tatsuji

2004-03-01

By using lactose colored with erythrocin, we examined the effect of particle size on mixing degree during the preparation of triturations with a mortar and pestle. We used powders with different distributions of particle sizes, i.e., powder that passed through 32-mesh but was trapped on a 42-mesh sieve (32/42-mesh powder), powder that passed through a 42-mesh sieve but was trapped on a 60-mesh sieve (42/60-mesh powder), powder that passed through a 60-mesh sieve but was trapped on a 100-mesh sieve (60/100-mesh powder), and powder that passes through a 100-mesh sieve (> 100-mesh powder). The mixing degree of colored powder and non-colored powder whose distribution of particle sizes was the same as that of the colored powder was excellent. The coefficient of variation (CV) value of the mixing degree was 6.08% after 40 rotations when colored powder was mixed with non-colored powder that both passed through a 100-mesh sieve. The CV value of the mixing degree was low in the case of mixing of colored and non-colored powders with different particle size distributions. After mixing, about 50% of 42/60-mesh powder had become smaller particles, whereas the distribution of particle sizes was not influenced by the mixing of 60/100-mesh powder. It was suggested that the mixing degree is affected by distribution of particle sizes. It may be important to determine the mixing degrees for drugs with narrow therapeutic ranges.

Influence of the shape of soaring particle based on coal-water slurry containing petrochemicals on ignition characteristics

Directory of Open Access Journals (Sweden)

Valiullin Timur R.

2017-01-01

Full Text Available This paper examines the laws of stable ignition of organic coal-water slurry containing petrochemicals (CWSP. The CWSP is based on the filter cake of coal and scavenge oil. The experiments are performed for individual CWSP particles soaring in a special set-up. The temperature and velocity of an oxidizer flow are varied between 500-1200 K, and 0.5-3 m/s. The dimensions (longitudinal and transverse of particles range are from 0.5 mm to 5 mm. The study indicates how the shape of a fuel particle (sphere, ellipsoid, and polyhedron influences its ignition characteristics (delay time, minimum temperature, modes, stages. Based on the experimental results, the paper explains why the surface configuration of particles influences the conditions of heat transfer with an oxidizer. The results obtained for soaring particles are compared with the results for fixed CWSP particles having different surface configurations (sphere, ellipsoid, and polyhedron. In general, the study may contribute to the expansion of the fuel resource base. The experimental data may be used for the development of the technologies of burning CWSP prepared by recycling traditional fuels. As a result of this study, several recommendations for the practical application of research results are made.

Inverse problem for particle size distributions of atmospheric aerosols using stochastic particle swarm optimization

International Nuclear Information System (INIS)

Yuan Yuan; Yi Hongliang; Shuai Yong; Wang Fuqiang; Tan Heping

2010-01-01

As a part of resolving optical properties in atmosphere radiative transfer calculations, this paper focuses on obtaining aerosol optical thicknesses (AOTs) in the visible and near infrared wave band through indirect method by gleaning the values of aerosol particle size distribution parameters. Although various inverse techniques have been applied to obtain values for these parameters, we choose a stochastic particle swarm optimization (SPSO) algorithm to perform an inverse calculation. Computational performances of different inverse methods are investigated and the influence of swarm size on the inverse problem of computation particles is examined. Next, computational efficiencies of various particle size distributions and the influences of the measured errors on computational accuracy are compared. Finally, we recover particle size distributions for atmospheric aerosols over Beijing using the measured AOT data (at wavelengths λ=0.400, 0.690, 0.870, and 1.020 μm) obtained from AERONET at different times and then calculate other AOT values for this band based on the inverse results. With calculations agreeing with measured data, the SPSO algorithm shows good practicability.

Influence of particle size distributions on magnetorheological fluid performances

International Nuclear Information System (INIS)

Chiriac, H; Stoian, G

2010-01-01

In this paper we investigate the influence that size distributions of the magnetic particles might have on the magnetorheological fluid performances. In our study, several size distributions have been tailored first by sieving a micrometric Fe powder in order to obtain narrow distribution powders and then by recomposing the new size distributions (different from Gaussian). We used spherical Fe particles (mesh -325) commercially available. The powder was sieved by means of a sieve shaker using a series of sieves with the following mesh size: 20, 32, 40, 50, 63, 80 micrometers. All magnetic powders were characterized through Vibrating Sample Magnetometer (VSM) measurements, particle size analysis and also Scanning Electron Microscope (SEM) images were taken. Magnetorheological (MR) fluids based on the resulted magnetic powders were prepared and studied by means of a rheometer with a magnetorheological module. The MR fluids were measured in magnetic field and in zero magnetic field as well. As we noticed in our previous experiments particles size distribution can also influence the MR fluids performances.

Mesoporous activated carbons with metal-oxide particles prepared from Morwell coal; Morwell tan wo genryo to shita kinzoku sankabutsu tanji kasseitan no saiko kozo

Energy Technology Data Exchange (ETDEWEB)

Yoshizawa, N.; Yamada, Y.; Shiraishi, M. [National Institute for Resources and Environment, Tsukuba (Japan); Kojima, S.; Tamai, H.; Yasuda, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

1996-10-28

The metal dependence of mesoporous activated carbons with various metal acetylacetonate (acac) particles prepared from Morwell coal was studied. In experiment, the mixture of Morwell coal and acac metal complexes were dissipated into tetrahydrofuran, and after agitation in Ar atmosphere, the solvent was removed by vacuum distillation. Coal specimens with Fe(acac)3, Ni(acac)2 and Co(acac)2 as acac complexes were activated by exchanging flow gas with water vapor after heat treatment in N2 gas flow at 900{degree}C. The pore sizes of the specimens were obtained from N2 adsorption isotherms by BET method and BJH method. Conditions of pores and metals in the specimens were examined by XRD measurement and TEM observation. The relation between the above conditions and pore characteristics obtained from adsorption experiment was also examined. As a result, the difference in mesopore ratio between the specimens and blank specimens was larger in the order of Fe, Co and Ni, and the effect of added metal complexes was also larger in this order. 3 refs., 3 figs., 3 tabs.

Size and Velocity Distributions of Particles and Droplets in Spray Combustion Systems.

Science.gov (United States)

1984-11-01

34Particle Sizing by Optical , Nonimaging Techniques," Liquid Particle Size _Mjur-mentTechnjgjwi, ASTM publications STP848, ed. by J. MI. Tishkoff, R. D... Optical Nonimaging predictions do not account for nonideal lens effects. Techniques," in Liquid Particle Size Measurement Techniques, J.M.Tishkoff, ed...4S E. Dan Hirleman’ Particle Sizing by Optical , Nonimaging Techniques REFERENCE: Hieleman, E. D., "Particle Sizing by Optical , Nonimaging Tech- niques

Effect of particle size distribution on sintering of tungsten

International Nuclear Information System (INIS)

Patterson, B.R.; Griffin, J.A.

1984-01-01

To date, very little is known about the effect of the nature of the particle size distribution on sintering. It is reasonable that there should be an effect of size distribution, and theory and prior experimental work examining the effects of variations in bimodal and continuous distributions have shown marked effects on sintering. Most importantly, even with constant mean particle size, variations in distribution width, or standard deviation, have been shown to produce marked variations in microstructure and sintering rate. In the latter work, in which spherical copper powders were blended to produce lognormal distributions of constant geometric mean particle size by weight frequency, blends with larger values of geometric standard deviation, 1nσ, sintered more rapidly. The goals of the present study were to examine in more detail the effects of variations in the width of lognormal particle size distributions of tungsten powder and determine the effects of 1nσ on the microstructural evolution during sintering

Element content and particle size characterization of a mussel candidate reference material

International Nuclear Information System (INIS)

Moreira, Edson G.; Vasconcellos, Marina B.A.; Santos, Rafaela G. dos; Martinelli, Jose R.

2011-01-01

The use of certified reference materials is an important tool in the quality assurance of analytical measurements. To assure reliability on recently prepared powder reference materials, not only the characterization of the property values of interest and their corresponding uncertainties, but also physical properties such as the particle size distribution must be well evaluated. Narrow particle size distributions are preferable than larger ones; as different size particles may have different analyte content. Due to this fact, the segregation of the coarse and the fine particles in a bottle may lead to inhomogeneity of the reference material, which should be avoided. In this study the element content as well as the particle size distribution of a mussel candidate reference material produced at IPEN-CNEN/SP was investigated. Instrumental Neutron Activation Analysis was applied to the determination of 15 elements in seven fractions of the material with different particle size distributions. Subsamples of the materials were irradiated simultaneously with elemental standards at the IEA-R1 research nuclear reactor and the induced gamma ray energies were measured in a hyperpure germanium detector. Three vials of the candidate reference material and three coarser fractions, collected during the preparation, were analyzed by Laser Diffraction Particle Analysis to determine the particle size distribution. Differences on element content were detected for fractions with different particle size distribution, indicating the importance of particle size control for biological reference materials. From the particle size analysis, Gaussian particle size distribution was observed for the candidate reference material with mean particle size μ = 94.6 ± 0.8 μm. (author)

Pressure Prediction of Coal Slurry Transportation Pipeline Based on Particle Swarm Optimization Kernel Function Extreme Learning Machine

Directory of Open Access Journals (Sweden)

Xue-cun Yang

2015-01-01

Full Text Available For coal slurry pipeline blockage prediction problem, through the analysis of actual scene, it is determined that the pressure prediction from each measuring point is the premise of pipeline blockage prediction. Kernel function of support vector machine is introduced into extreme learning machine, the parameters are optimized by particle swarm algorithm, and blockage prediction method based on particle swarm optimization kernel function extreme learning machine (PSOKELM is put forward. The actual test data from HuangLing coal gangue power plant are used for simulation experiments and compared with support vector machine prediction model optimized by particle swarm algorithm (PSOSVM and kernel function extreme learning machine prediction model (KELM. The results prove that mean square error (MSE for the prediction model based on PSOKELM is 0.0038 and the correlation coefficient is 0.9955, which is superior to prediction model based on PSOSVM in speed and accuracy and superior to KELM prediction model in accuracy.

Determination of moisture in black coal using pulsed nuclear magnetic resonance spectrometry

International Nuclear Information System (INIS)

Cutmore, N.G.; Sowerby, B.D.; Lynch, L.J.; Webster, D.S.

1987-01-01

Pulsed nuclear magnetic resonance (n.m.r.) spectrometry was investigated as a technique for moisture determination in fine product coal from eight Australian coal washeries. Measurements were made on samples of diameter 8 and 12 mm and length 10 and 120 mm at frequencies from 6.5 to 60 MHz. The ratio of intensities of the water and coal components in the free-induction decay signal can be used to determine moisture to within approx. 0.4-0.7 wt% over the range 0-26 wt% moisture, independent of sample density. This accuracy is independent of particle size (up to 1 mm) and little affected by coal rank, sample length or n.m.r. frequency. (author)

[Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

Science.gov (United States)

Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

2014-09-01

Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

Sizes of particles formed during municipal wastewater treatment.

Science.gov (United States)

Lech, Smoczynski; Marta, Kosobucka; Michal, Smoczynski; Harsha, Ratnaweera; Krystyna, Pieczulis-Smoczynska

2017-02-01

Volumetric diameters Dv and specific surface area SpS of sludge particles formed during chemical coagulation and electrocoagulation of sewage were determined. The obtained aggregate-flocs differed substantially in both Dv and SpS values. The differences in Dv and SpS values of the analyzed particles were interpreted based on theoretical models for expanding aggregates. The most uniform particles were formed under exposure to: (a) optimal and maximal doses of PIX, (b) optimal doses of PAX, (c) maximal doses of the Al electro-coagulant. The lowest PIX dose produced the least uniform particles. Sludge aggregates-particles produced under exposure to minimal doses of PIX and the Al electro-coagulant were characterized by the lowest SpS values. Sludge particles coagulated by PAX and the particles formed at higher doses of PIX and the Al electro-coagulant had higher SpS values. The particles formed at all doses of the applied coagulants and electro-coagulants were generally classified into two size ranges: the main range and the secondary range. Most particles belonged to the main size range. An increase in the percentage of colloidal hydroxide particles in sewage sludge increased SpS.

Pillar size optimization design of isolated island panel gob-side entry driving in deep inclined coal seam—case study of Pingmei No. 6 coal seam

Science.gov (United States)

Zhang, Shuai; Wang, Xufeng; Fan, Gangwei; Zhang, Dongsheng; Jianbin, Cui

2018-06-01

There is a perception that deep roadways are difficult to maintain. To reverse this and to improve the recovery rate of coal resources, gob-side entry driving is widely used in coal mines, especially deep-mining coal mines, in China. Determination of the reasonable pillar size through in situ observation and experimentation plays a vital role for roadway maintenance. Based on the geological conditions of Pingmei No.6 coal seam, a theoretical analysis, numerical simulation, and industrial experiments are carried out to calculate the reasonable width of chain pillars, analyze the lateral support stress distribution law near the gob side, investigate the relationship between the coal pillar stress distribution, roadway surrounding rock stress distribution, roadway surrounding rock deformation and the coal pillar width. The results indicate that 5 m wide coal pillars can ensure that the chain pillars are at a lower stress level and the deformation of roadway surrounding rock is in a more reasonable range. Industrial experiments show that when the chain pillar width is 5 m, the deformation of roadway surrounding rock can meet the requirements of working face safe production. The numerical results agreed well with field measurement and observations, and the industrial experiments results further validated the results of the numerical simulation.

Detonation limits of clouds of coal dust in mixtures of oxygen and nitrogen

Energy Technology Data Exchange (ETDEWEB)

Edwards, D.H.; Fearnley, P.J.; Nettleton, M.A.

1987-09-01

Ignition and the subsequent acceleration of flame in clouds of coal dust dispersed in mixtures of oxygen and nitrogen have been studied. Two coal sizes, 24 and 54 ..mu..m, in concentrations ranging from 0.05 to 0.22 kg/m/sup 3/ were employed. Flame acceleration and the approach to transition to a stable detonation were monitored by a combination of microwave interferometry and pressure measurements. Flame and shock velocities up to 1.85 km/sec were observed. Ignition distances were found to be independent of the concentrations of dust and oxygen and particle size.

Concentration and size distribution of particles in abstracted groundwater

NARCIS (Netherlands)

Van Beek, C.G.E.M.; de Zwart, A.H.; Balemans, M.; Kooiman, J.W.; van Rosmalen, C.; Timmer, H.; Vandersluys, J.; Stuijfzand, P.J.

2010-01-01

Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of

Particle sizing experiments with the laser Doppler velocimeter: Final report

Energy Technology Data Exchange (ETDEWEB)

Giel, T.V. Jr.; Son, J.Y.

1988-06-01

Measurement techniques for in-situ simultaneous measurements of particle size distributions and particle velocities using the dual beam laser Doppler velocimeter (LV) were analytically and experimentally investigated. This investigation examined the different signal characteristics of the LV for determination of particle size and particle velocity, simultaneously. The different size related signal components were evaluated not only singularly but also as simultaneous measurements to determine which characteristic, or combination of characteristics, provided the best measure of particle size. The evaluation concentrated on the 0.5 to 5 ..mu..m particle size range, in which the LV light scattering characteristics are complex often non-monotonic functions of the particle size as well as functions of index of refraction, the laser light wavelength, laser intensity and polarization, and the location and response characteristics of the detector. Different components of the LV signal were considered, but analysis concentrated on Doppler phase, visibility and scatter-intensity because they show the greatest promise. These signals characteristics were initially defined analytically for numerous optical configurations over the 0.5 to 5 ..mu..m diameter range with 0.1 ..mu..m segmentation, for refractive index values from 1.0 to 3.0 with absorptive (imaginary) components varied form 0 to 1.0. Collector orientation and effective f/No., as well as fringe spacing, beam polarization and wavelength, were varied in this analytical evaluation. 18 refs., 42 figs., 5 tabs.

Physico-chemical and optical properties of combustion-generated particles from coal-fired power plant, automobile and ship engine and charcoal kiln.

Science.gov (United States)

Kim, Hwajin

2015-04-01

Similarities and differences in physico-chemical and optical properties of combustion generated particles from various sources were investigated. Coal-fired power plant, charcoal kiln, automobile and ship engine were major sources, representing combustions of coal, biomass and two different types of diesel, respectively. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX) equipped with both SEM and HRTEM were used for physico-chemical analysis. Light absorbing properties were assessed using a spectrometer equipped with an integrating sphere. Particles generated from different combustion sources and conditions demonstrate great variability in their morphology, structure and composition. From coal-fired power plant, both fly ash and flue gas were mostly composed of heterogeneously mixed mineral ash spheres, suggesting that the complete combustion was occurred releasing carbonaceous species out at high temperature (1200-1300 °C). Both automobile and ship exhausts from diesel combustions show typical features of soot: concentric circles comprised of closely-packed graphene layers. However, heavy fuel oil (HFO) combusted particles from ship exhaust demonstrate more complex compositions containing different morphology of particles other than soot, e.g., spherical shape of char particles composed of minerals and carbon. Even for the soot aggregates, particles from HFO burning have different chemical compositions; carbon is dominated but Ca (29.8%), S (28.7%), Na(1%), and Mg(1%) are contained, respectively which were not found from particles of automobile emission. This indicates that chemical compositions and burning conditions are significant to determine the fate of particles. Finally, from biomass burning, amorphous and droplet-like carbonaceous particles with no crystallite structure are observed and they are generally formed by the condensation of low volatile species at low

The pentane- and toluene-soluble fractions of a petroleum residue and three coal tars by size exclusion chromatography and UV-fluorescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Karaca, F.; Millan-Agorio, M.; Morgan, T.J.; Bull, I.D.; Herod, A.A.; Kandiyoti, R. [University of London Imperial College Science Technology & Medicine, London (United Kingdom). Dept. of Chemical Engineering

2008-01-15

A petroleum atmospheric pressure distillate residue and three tars derived from different coals using different severities of thermal treatment were separated into seven fractions using column chromatography on silica and sequential elution by the solvent sequence pentane, toluene, acetonitrile, pyridine, 1-methyl-2-pyrrolidinone (NMP) and water. The fractions from the four extractions have been compared using size exclusion chromatography (SEC) in NMP as eluent and by synchronous ultra-violet-fluorescence (UV-F). This paper concerns the pentane and toluene soluble fractions only since these are the least polar fractions. By SEC, the size of the aromatic molecules increased from the first pentane soluble fractions to the toluene-soluble fractions, with the petroleum residue fractions of larger size than the equivalent fractions from coal liquids. The three coal tars showed significant differences, indicating that temperature of pyrolysis had a significant effect on the molecular size. Synchronous UV-F spectra of the four sets of fractions, in solution in NMP, again showed significant differences between the petroleum residue and the coal tars, as well as amongst the three coal tars. In general, the petroleum residue fractions contained smaller aromatic clusters than the coal liquid fractions. These low-polarity fractions contained material excluded from the column porosity in SEC that was unlikely to consist of aggregates of polar molecules.

Effects of fuel particle size distributions on neutron transport in stochastic media

International Nuclear Information System (INIS)

Liang, Chao; Pavlou, Andrew T.; Ji, Wei

2014-01-01

Highlights: • Effects of fuel particle size distributions on neutron transport are evaluated. • Neutron channeling is identified as the fundamental reason for the effects. • The effects are noticeable at low packing and low optical thickness systems. • Unit cells of realistic reactor designs are studied for different size particles. • Fuel particle size distribution effects are not negligible in realistic designs. - Abstract: This paper presents a study of the fuel particle size distribution effects on neutron transport in three-dimensional stochastic media. Particle fuel is used in gas-cooled nuclear reactor designs and innovative light water reactor designs loaded with accident tolerant fuel. Due to the design requirements and fuel fabrication limits, the size of fuel particles may not be perfectly constant but instead follows a certain distribution. This brings a fundamental question to the radiation transport computation community: how does the fuel particle size distribution affect the neutron transport in particle fuel systems? To answer this question, size distribution effects and their physical interpretations are investigated by performing a series of neutron transport simulations at different fuel particle size distributions. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. A total of 15 parametric cases are constructed by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (k eff ) and the spatial distribution of fission power density along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution shows a noticeable effect on neutron

Effect of Particle Size Distribution on Slurry Rheology: Nuclear Waste Simulant Slurries

International Nuclear Information System (INIS)

Chun, Jaehun; Oh, Takkeun; Luna, Maria L.; Schweiger, Michael J.

2011-01-01

Controlling the rheological properties of slurries has been of great interest in various industries such as cosmetics, ceramic processing, and nuclear waste treatment. Many physicochemical parameters, such as particle size, pH, ionic strength, and mass/volume fraction of particles, can influence the rheological properties of slurry. Among such parameters, the particle size distribution of slurry would be especially important for nuclear waste treatment because most nuclear waste slurries show a broad particle size distribution. We studied the rheological properties of several different low activity waste nuclear simulant slurries having different particle size distributions under high salt and high pH conditions. Using rheological and particle size analysis, it was found that the percentage of colloid-sized particles in slurry appears to be a key factor for rheological characteristics and the efficiency of rheological modifiers. This behavior was shown to be coupled with an existing electrostatic interaction between particles under a low salt concentration. Our study suggests that one may need to implement the particle size distribution as a critical factor to understand and control rheological properties in nuclear waste treatment plants, such as the U.S. Department of Energy's Hanford and Savannah River sites, because the particle size distributions significantly vary over different types of nuclear waste slurries.

Investigation of combustion of coal briquettes in a fluidized bed reactor

Energy Technology Data Exchange (ETDEWEB)

Boavida, Dulce; Abelha, Pedro; Gulyurtlu, Ibrahim; Cabrita, Isabel

1999-07-01

This paper discusses the results obtained from an experimental combustion work undertaken to investigate the behaviour of multicomponent briquettes, prepared by mixing two different particle sizes of coal and two different types of binder species. single briquettes were burned over a wide range of temperatures in a laboratory scale fluidised bed combustor facility. Nitrogen (NO{sub x}, and N{sub 2}O) and Sulphur (SO{sub 2}) oxides emissions resulting from the combustion of these briquettes were constantly monitored during the time of burning. The levels of O{sub 2}, CO{sub 2} and CO were also recorded during the same period. Experimental results showed that coal particle size influenced burn-out times and emissions levels of some of gaseous species. The hinder type was also found to have a major influence on the emissions of different pollutants.The temperature was observed to significantly influence the extent of the effects of the other operating parameters studied.

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.

Study on the technology of decreasing ash and sulfur in coking coal concentrate by deep-cleaning

Energy Technology Data Exchange (ETDEWEB)

Li, A.; Li, P.; Chen, S. [Hefei Design and Research Institute of Coal Industry, Hefei (China)

2007-06-15

Middling fractions of coking coal, a rare resource in China, were analysed for their embedded minerals both in kind and distribution. Observation with a microscope shows that most are clay minerals of very small particle size. The embedded minerals can be liberated from middling by grinding. Clean coal can be obtained from ground middling by the flocculation-flotation process. The yield of clean coal could thus be increased and its ash and sulfur content decreased. 3 refs., 2 figs., 4 tabs.

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.

Experimental investigation of particle size distribution influence on diffusion controlled coarsening

International Nuclear Information System (INIS)

Fang, Zhigang; Patterson, B.R.

1993-01-01

The influence of initial particle size distribution on coarsening during liquid phase sintering has been experimentally investigated using W-14Ni-6Fe alloy as a model system. It was found that initially wider size distribution particles coarsened more rapidly than those of an initially narrow distribution. The well known linear relationship between the cube of the average particle radius bar r -3 , and time was observed for most of the coarsening process, although the early stage coarsening rate constant changed with time, as expected with concomitant early changes in the tungsten particle size distribution. The instantaneous transient rate constant was shown to be related to the geometric standard deviation, 1nσ, of the instantaneous size distributions, with higher rate constants corresponding to larger 1nσ values. The form of the particle size distributions changed rapidly during early coarsening and reached a quasi-stable state, different from the theoretical asymptotic distribution, after some time. A linear relationship was found between the experimentally observed instantaneous rate constant and that computed from an earlier model incorporating the effect of particle size distribution. The above results compare favorably with those from prior theoretical modeling and computer simulation studies of the effect of particle size distribution on coarsening, based on the DeHoff communicating neighbor model

Research on bimodal particle extinction coefficient during Brownian coagulation and condensation for the entire particle size regime

International Nuclear Information System (INIS)

Tang Hong; Lin Jianzhong

2011-01-01

The extinction coefficient of atmospheric aerosol particles influences the earth’s radiation balance directly or indirectly, and it can be determined by the scattering and absorption characteristics of aerosol particles. The problem of estimating the change of extinction coefficient due to time evolution of bimodal particle size distribution is studied, and two improved methods for calculating the Brownian coagulation coefficient and the condensation growth rate are proposed, respectively. Through the improved method based on Otto kernel, the Brownian coagulation coefficient can be expressed simply in powers of particle volume for the entire particle size regime based on the fitted polynomials of the mean enhancement function. Meanwhile, the improved method based on Fuchs–Sutugin kernel is developed to obtain the condensation growth rate for the entire particle size regime. And then, the change of the overall extinction coefficient of bimodal distributions undergoing Brownian coagulation and condensation can be estimated comprehensively for the entire particle size regime. Simulation experiments indicate that the extinction coefficients obtained with the improved methods coincide fairly well with the true values, which provide a simple, reliable, and general method to estimate the change of extinction coefficient for the entire particle size regime during the bimodal particle dynamic processes.

Size-based sorting of micro-particles using microbubble streaming

Science.gov (United States)

Wang, Cheng; Jalikop, Shreyas; Hilgenfeldt, Sascha

2009-11-01

Oscillating microbubbles driven by ultrasound have shown great potential in microfluidic applications, such as transporting particles and promoting mixing [1-3]. The oscillations generate secondary steady streaming that can also trap particles. We use the streaming to develop a method of sorting particles of different sizes in an initially well-mixed solution. The solution is fed into a channel consisting of bubbles placed periodically along a side wall. When the bubbles are excited by an ultrasound piezo-electric transducer to produce steady streaming, the flow field is altered by the presence of the particles. This effect is dependent on particle size and results in size-based sorting of the particles. The effectiveness of the separation depends on the dimensions of the bubbles and particles as well as on the ultrasound frequency. Our experimental studies are aimed at a better understanding of the design and control of effective microfluidic separating devices. Ref: [1] P. Marmottant and S. Hilgenfeldt, Nature 423, 153 (2003). [2] P. Marmottant and S. Hilgenfeldt, Proc. Natl. Acad. Science USA, 101, 9523 (2004). [3] P. Marmottant, J.-P. Raven, H. Gardeniers, J. G. Bomer, and S. Hilgenfeldt, J. Fluid Mech., vol.568, 109 (2006).

The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

Science.gov (United States)

Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

2013-12-01

Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

Identification of nanominerals and nanoparticles in burning coal waste piles from Portugal

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Joana [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Flores, Deolinda [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Departamento de Geociencias, Ambiente e Ordenamento do Territorio, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Ward, Colin R. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 (Australia); Silva, Luis F.O., E-mail: felipeqma@yahoo.com.br [Catarinense Institute of Environmental Research and Human Development, IPADHC, Capivari de Baixo, Santa Catarina (Brazil)

2010-11-01

A range of carbon nanoparticles, agglomerates and mineral phases have been identified in burning coal waste pile materials from the Douro Coalfield of Portugal, as a basis for identifying their potential environmental and human health impacts. The fragile nature and fine particle size of these materials required novel characterization methods, including energy-dispersive X-ray spectrometry (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) techniques. The chemical composition and possible correlations with morphology of the nanominerals and associated ultra-fine particles have been evaluated in the context of human health exposure, as well as in relation to management of such components in coal-fire environments.

The effects of particle size distribution and induced unpinning during grain growth

International Nuclear Information System (INIS)

Thompson, G.S.; Rickman, J.M.; Harmer, M.P.; Holm, E.A.

1996-01-01

The effect of a second-phase particle size distribution on grain boundary pinning was studied using a Monte Carlo simulation technique. Simulations were run using a constant number density of both whisker and rhombohedral particles, and the effect of size distribution was studied by varying the standard deviation of the distribution around a constant mean particle size. The results of present simulations indicate that, in accordance with the stereological assumption of the topological pinning model, changes in distribution width had no effect on the pinned grain size. The effect of induced unpinning of particles on microstructure was also studied. In contrast to predictions of the topological pinning model, a power law dependence of pinned grain size on particle size was observed at T=0.0. Based on this, a systematic deviation to the stereological predictions of the topological pinning model is observed. The results of simulations at higher temperatures indicate an increasing power law dependence of pinned grain size on particle size, with the slopes of the power law dependencies fitting an Arrhenius relation. The effect of induced unpinning of particles was also studied in order to obtain a correlation between particle/boundary concentration and equilibrium grain size. The results of simulations containing a constant number density of monosized rhombohedral particles suggest a strong power law correlation between the two parameters. copyright 1996 Materials Research Society

Method for rapid particle size analysis by hydrosizing and nuclear sensing

International Nuclear Information System (INIS)

Daellenbach, C.B.; Mahan, W.M.

1977-01-01

A method and apparatus to practice the method for rapidly determining the size and mass distribution of a sample of randomly sized particles of a known total mass are described. A series of substantially identical hydrocyclones are connected by conduits to each other and to a temperature controlled water feed. By restricting the cross-sectional areas of these conduits to progressively smaller values, the slurry containing the sample particles is caused to increase its velocity as it moves from hydrocyclone to hydrocyclone. As described by the Stokesian theory which relates particle diameter and settling velocity, the largest sized particles are suspended in the closed apex of the first hydrocyclone with smaller sized particles, in given size ranges, being suspended in the next succeeding hydrocyclone's apexes. In this manner, the particles are separated into discrete fractional sizes with a residual slurry of the very smallest particles being discharged. Before the discrete fractions of particles are suspended in their hydrocyclone apexes, a combined photon source, like a gamma ray source, and detector are calibrated with the water temperature kept constant. When the suspension of particles takes place, an attenuation of the radiation from the source is observed at the detector. This attenuation can be related to the mass or weight of the discrete fractions of suspended particles. Electronic circuitry is used to indicate what this fractional mass or weight is as it relates to the total weight of the sample. 6 claims, 4 figs

Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion

Energy Technology Data Exchange (ETDEWEB)

Stephanie Lucero Konopa; James A. Mulholland; Matthew J. Realff; Paul M. Lemieux [Georgia Institute of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering

2008-08-15

The use of post-consumer carpet as a potential fuel substitute in cement kilns and other high-temperature processes is being considered to address the problem of huge volumes of carpet waste and the opportunity of waste-to-energy recovery. Carpet represents a high volume waste stream, provides high energy value, and contains other recoverable materials for the production of cement. This research studied the emission characteristics of burning 0.46-kg charges of chopped nylon carpet squares, pulverized coal, and particle-board pellets in a pilot-scale natural gas-fired rotary kiln. Carpet was tested with different amounts of water added. Emissions of oxygen, carbon dioxide, nitric oxide (NO), sulfur dioxide (SO{sub 2}), carbon monoxide (CO), and total hydrocarbons and temperatures were continuously monitored. It was found that carpet burned faster and more completely than coal and particle board, with a rapid volatile release that resulted in large and variable transient emission peaks. NO emissions from carpet combustion ranged from 0.06 to 0.15 g/MJ and were inversely related to CO emissions. Carpet combustion yielded higher NO emissions than coal and particleboard combustion, consistent with its higher nitrogen content. S{sub 2} emissions were highest for coal combustion, consistent with its higher sulfur content than carpet or particle board. Adding water to carpet slowed its burn time and reduced variability in the emission transients, reducing the CO peak but increasing NO emissions. Results of this study indicate that carpet waste can be used as an effective alternative fuel, with the caveats that it might be necessary to wet carpet or chop it finely to avoid excessive transient puff emissions due to its high volatility compared with other solid fuels, and that controlled mixing of combustion air might be used to control NO emissions from nylon carpet. 13 refs., 5 figs., 1 tab.

Particle size distribution of plutonium contaminated soil

International Nuclear Information System (INIS)

Zeng Ke; Wu Wangsuo; Jin Yuren; Shen Maoquan; Han Zhaoyang; Hu Zhiqian; Ma Teqi

2012-01-01

Wet classification and γ ray spectroscopy had been applied to study the particle size distribution of Pu in the desert soil of somewhere in Northern China. It was found that nearly 90% of Pu exits in 0.1-10 mm particles. only 10% less in particles under 0.05 mm that still poses notable hazards to biosphere if any resuspension. Providing a decontamination target of 239 Pu <4000 Bq/kg, accident condition. (authors)

The level of air pollution in the impact zone of coal-fired power plant (Karaganda City) using the data of geochemical snow survey (Republic of Kazakhstan)

Science.gov (United States)

Adil'bayeva, T. E.; Talovskaya, A. V.; Yazikov, Ye G.; Matveenko, I. A.

2016-09-01

Coal-fired power plants emissions impact the air quality and human health. Of great significance is assessment of solid airborne particles emissions from those plants and distance of their transportation. The article presents the results of air pollution assessment in the zone of coal-fired power plant (Karaganda City) using snow survey. Based on the mass of solid airborne particles deposited in snow, time of their deposition on snow at the distance from 0.5 to 4.5 km a value of dust load has been determined. It is stated that very high level of pollution is observed at the distance from 0.5 to 1 km. there is a trend in decrease of dust burden value with the distance from the stacks of coal-fired power plant that may be conditioned by the particle size and washing out smaller ash particles by ice pellets forming at freezing water vapour in stacks of the coal-fired power plant. Study in composition of solid airborne particles deposited in snow has shown that they mainly contain particulates of underburnt coal, Al-Si- rich spheres, Fe-rich spheres, and coal dust. The content of the particles in samples decreases with the distance from the stacks of the coal-fired power plant.

Relationship between dioxin concentration and particle size for suspended sediment

Energy Technology Data Exchange (ETDEWEB)

Kitamura, K.; Sakurai, T.; Choi, J.W.; Suzuki, N.; Morita, M. [National Inst. for Environmental Studies, Tsukuba (Japan)

2004-09-15

The purpose of the present study was to find out how the amounts of adsorbed dioxins, i.e., polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/Fs), mono-ortho-polychlorinated biphenyls (PCBs) and non-ortho-PCBs, vary with the particle size of suspended sediment. As dioxins are hydrophobic, they tend to adsorb onto particles suspended in water, and the determination of which dioxin congeners readily dissolve in water or adsorb onto particles is central to the characterization of dioxin behavior in water/sediment systems. Presumably suspension of sediments and the size of the particles govern the transfer of dioxins to aquatic organisms. Therefore, in the present study, we investigated the relationship between the amount of dioxins and the particle-size distribution of resuspended, rather than settled, sediment.

Size-resolved particle emission factors for individual ships

Science.gov (United States)

Jonsson, Åsa M.; Westerlund, Jonathan; Hallquist, Mattias

2011-07-01

In these experiments size-resolved emission factors for particle number (EFPN) and mass (EFPM) have been determined for 734 individual ship passages for real-world dilution. The method used is an extractive sampling method of the passing ship plumes where particle number/mass and CO2 were measured with high time resolution (1 Hz). The measurements were conducted on a small island located in the entrance to the port of Gothenburg (N57.6849, E11.838), the largest harbor in Scandinavia. This is an emission control area (ECA) and in close vicinity to populated areas. The average EFPN and EFPM were 2.55 ± 0.11 × 1016 (kg fuel)-1 and 2050 ± 110 mg (kg fuel)-1, respectively. The determined EF for ships with multiple passages showed a great reproducibility. Size-resolved EFPN were peaking at small particle sizes ˜35 nm. Smaller particle sizes and hence less mass were observed by a gas turbine equipped ship compared to diesel engine equipped ships. On average 36 to 46% of the emitted particles by number were non-volatile and 24% by mass (EFPN 1.16 ± 0.19 × 1016 [kg fuel]-1 and EFPM 488 ± 73 mg [kg fuel]-1, respectively). This study shows a great potential to gain large data-sets regarding ship emission determining parameters that can improve current dispersion modeling for health assessments on local and regional scales. The global contributions of total and non-volatile particle mass from shipping using this extensive data-set from an ECA were estimated to be at least 0.80 Tgy-1 and 0.19 Tgy-1.

Size-selective separation of submicron particles in suspensions with ultrasonic atomization.

Science.gov (United States)

Nii, Susumu; Oka, Naoyoshi

2014-11-01

Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. Copyright © 2014 Elsevier B.V. All rights reserved.

Soot particle size measurements in ethylene diffusion flames at elevated pressures

KAUST Repository

Steinmetz, Scott

2016-05-07

Soot particle size is investigated in laminar nitrogen-diluted ethylene coflow diffusion flames at 4, 8, 12 and 16 atm. Line of sight attenuation and scattering are used to measure two-dimensional soot volume fraction and particle size fields for the first time at elevated pressures. Soot volume fraction dependence on pressure is consistent with the observations of similar studies, scaling approximately with the square of pressure. Scattering intensity is analyzed through Rayleigh and Rayleigh-Debye-Gans polydisperse fractal aggregate theories to provide two estimates of particle size. An increase in overall particle sizes with pressure is found, consistent with similar one-dimensional studies. Particle diameters in the annulus of the flame increase faster with pressure than those on centerline. Contrary to previous studies, the dependence of particle size on pressure was found to taper off between 8 and 12 atm, with little observed growth beyond 12 atm. The measurements provide additional data for one of the International Sooting Flame (ISF) workshop\\'s target pressurized flames.

The effects of pf grind quality on coal burnout in a 1 MW combustion test facility

Energy Technology Data Exchange (ETDEWEB)

Richelieu Barranco; Michael Colechin; Michael Cloke; Will Gibb; Edward Lester [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering, Nottingham Fuel and Energy Centre

2006-05-15

A study was carried out to determine the effect of pf particle size distribution on coal burnout propensity in a 1 MW pulverised fuel burner. The specific aim of the work was to assess the improvement in combustion performance achievable by retrofitting commercially available high performance static or dynamic classifiers to existing plants. Two coals were used and were selected as representative of extremes in fuel characteristics experienced by coal importing utilities in Europe. Each coal was fired in the unit at a range of grind sizes to determine the overall impact of a variable performance from a mill. The levels of unburnt carbon in the resultant flyashes for the two coals showed significantly different behaviour. For the higher volatile coal, the unburnt carbon was found to be insensitive to grind quality. However, the coarser grinds of the other coal produced significantly lower unburnt carbon than expected when compared with the finest grinds. Generally the results indicate that the installation of improved classification technology, leading to a finer product, will help to lower unburnt carbon levels. Nevertheless, further work will be necessary to establish the levels of diminishing returns for grind size, burnout performance and grind costs. 21 refs., 4 figs., 4 tabs.

The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

International Nuclear Information System (INIS)

Zhang, Bo; Edwards, Brian J.

2015-01-01

A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes

The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes.

Science.gov (United States)

Zhang, Bo; Edwards, Brian J

2015-06-07

A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

Gasifier feed: Tailor-made from Illinois coals. Technical report, September 1, 1991--November 30, 1991

Energy Technology Data Exchange (ETDEWEB)

Ehrlinger, H.P. III

1991-12-31

The purpose of this research is to develop a coal slurry from waste streams using Illinois coal that is ideally suited for a gasification feed. The principle items to be studied are (1) methods of concentrating pyrite and decreasing other ash forming minerals into a high grade gasification feed using froth flotation and gravity separation techniques; (2) chemical and particle size analyses of coal slurries; (3) determination of how that slurry can be densified and to what degree of densification is optimum from the pumpability and combustibility analyses; and (4) reactivity studies.

Improved soil particle-size analysis by gamma-ray attenuation

International Nuclear Information System (INIS)

Oliveira, J.C.M.; Vaz, C.M.P.; Reichardt, K.; Swartzendruber, D.

1997-01-01

The size distribution of particles is useful for physical characterization of soil. This study was conducted to determine whether a new method of soil particle-size analysis by gamma-ray attenuation could be further improved by changing the depth and time of measurement of the suspended particle concentration during sedimentation. In addition to the advantage of nondestructive, undisturbed measurement by gamma-ray attenuation, as compared with conventional pipette or hydrometer methods, the modifications here suggested and employed do substantially decrease the total time for analysis, and will also facilitate total automation and generalize the method for other sedimentation studies. Experimental results are presented for three different Brazilian soil materials, and illustrate the nature of the fine detail provided in the cumulative particle-size distribution as given by measurements obtained during the relatively short time period of 28 min

Influence of Particle Size in Talc Suppression by a Galactomannan Depressant

Directory of Open Access Journals (Sweden)

Zhixiang Chen

2018-03-01

Full Text Available Flotation behavior of different sizes of particles may follow different trends. The influence of particle size in talc suppression by a depressant galactomannan was studied in this research. The flotation response and mechanism were examined by flotation tests, modified flotation rate constant and entrainment recovery calculation, laser particle size experiments, adsorption tests, and advancing contact angle measurement as well as scanning electron microscopy (SEM and energy dispersive X-ray spectrometry (EDS. The maximum recovery increased with particle size increases in the absence of galactomannan FPY (Fenugreek polysaccharide. The obviously suppressed effect was observed for the size fraction of −74 + 38 μm after reacting with FPY, but low efficiency was received for −38 μm and −10 μm, respectively. Laser particle size analysis indicated that the FPY has a certain function for the flocculation of fine particles. It is beneficial for reducing recovery by entrainment. EDS and advancing contact angle test results showed that the difference in contact angles probably is a result of genuine differences in the quantity of O and Mg bearing surface species, while the contact angle varied with particle size fraction in the absence of FPY. Adsorption and SEM test results demonstrated that in the case of −74 + 38 μm, the depressant adsorption density on the mineral surface is higher than the other two size fractions. On the whole, FPY probably is not enough of a depressant for talc suppression.

Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

Energy Technology Data Exchange (ETDEWEB)

Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

2017-09-12

Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

The Bulgarian coal and the fluid bed technology

International Nuclear Information System (INIS)

Konstantinov, M.; Georgiev, J.; Lebedov, K.; Petrov, N.

2000-01-01

Because of low-quality of the most of Bulgarian coal and more rigorous ecological restrictions for decreasing of greenhouse gases the fluidized bed technology is the most appropriate combustion technology. A study with a pilot plant aiming to establish the values of technological parameters in view to maintain stable process of fluidized bed combustion at the specific burning characteristics of the Bulgarian coal was carried out. Coal of different quality and particle size production of 'Marbas' LTD mines were used. Series of experiments with batches of strictly determined content were carried out at minimal, average and maximal load. The technological factors as: layer's aerodynamics, layer's height, fuel's quantity and quantity of inert material were changed at each batch. The ecological factors were optimized considering coal's quality, plant's parameters, limestone's dosing and layer's aerodynamics. A regressive model for optimization of technological and ecological factors was created. An average coefficient of performance was achieved, resp. 82.27 % at combustion of coal from mines 'Maritsa-West' and 90 % from mine 'Lev'. A coefficient of sulfur oxides' capture 70 % was obtained at coal with sulfur content 3.1-3.9 %. In conclusion the fluidized bed technology is very suitable for combustion's characteristics of the Bulgarian coal

Characterization of Oxy-combustion Impacts in Existing Coal-fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Bradley Adams; Andrew Fry; Constance Senior; Hong Shim; Huafeng Wang; Jost Wendt; Christopher Shaddix

2009-06-30

This report summarizes Year 1 results of a research program designed to use multi-scale experimental studies and fundamental theoretical models to characterize and predict the impacts of retrofit of existing coal-fired utility boilers for oxy-combustion. Through the course of Year 1 activities, great progress was made toward understanding the issues associated with oxy-combustion retrofit of coal-fired boilers. All four Year 1 milestones and objectives have been, or will be, completed on schedule and within budget. Progress in the four milestone areas may be summarized as follows: • University of Utah has performed size segregated ash composition measurements in the Oxy-Fuel Combustor (OFC). These experiments indicate that oxy-combustion retrofit may impact ash aerosol mineral matter composition. Both flame temperature and flue gas composition have been observed to influence the concentration of calcium, magnesium and iron in the fine particulate. This could in turn impact boiler fouling and slagging. • Sandia National Labs has shown that char oxidation rate is dependent on particle size (for sizes between 60 and 100 microns) by performing fundamental simulations of reacting char particles. These predictions will be verified by making time-resolved optical measurements of char particle temperature, velocity and size in bench-scale experiments before the end of Year 1. • REI and Siemens have completed the design of an oxy-research burner that will be mounted on University of Utah’s pilot-scale furnace, the L1500. This burner will accommodate a wide range of O2, FGR and mixing strategies under conditions relevant for utility boiler operation. Through CFD modeling of the different burner designs, it was determined that the key factor influencing flame stabilization location is particle heat-up rate. The new oxy-research burner and associated equipment is scheduled for delivery before the end of Year 1. • REI has completed a literature survey of slagging and

Preparation of gold nanoparticles and determination of their particles size via different methods

International Nuclear Information System (INIS)

Iqbal, Muhammad; Usanase, Gisele; Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar; Fessi, Hatem; Zine, Nadia; Agusti, Géraldine; Errachid, El-Salhi; Elaissari, Abdelhamid

2016-01-01

Graphical abstract: Preparation of gold nanoparticles via NaBH_4 reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH_4 reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH_4) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

Neutron activation analysis of Turkish coals Pt. 2

International Nuclear Information System (INIS)

Ayanoglu, S.F.; Guenduez, G.

1978-01-01

The analyses of the ashes of coals given in Part I were carried out and the percentage transferences of the elements into ash were determined (experimental parameters are given in Part I). Tabulated data are given. The dependence of the transferences of arsenic and selenium, known as very strong toxicants, on the particle size burnt and on the burning temperature was investigated. (T.G.)

Removal of unburned carbon in fly ash produced in coal combustion process

International Nuclear Information System (INIS)

Velasquez V, Leonardo F; De La Cruz M, Javier F; Sanchez M, Jhon F

2007-01-01

The coal unburned in flying ashes obtained in the processes of coal combustion is the main disadvantage for its use in the industry of the construction. This material normally has a size of particle greater than the mineral material, therefore it is possible to be separated in a considerable percentage, obtaining double benefit: the reusability of unburned like fuel or precursor for the activated charcoal production and the use of the mineral material in the industry of the construction since the organic matter has retired him that disables its use. In this work it is experienced with a sifted technique of separation by for three obtained flying ash samples with different technology (travelling Grill, pneumatic injection and overturning grill), were made grain sized analyses with meshes of a diameter of particle greater to 0,589 mm, the short analyses were made to them next to the retained material in each mesh and the unburned percentage of removal was determined of. The technique was compared with other developing.

Particle size-dependent radical generation from wildland fire smoke

International Nuclear Information System (INIS)

Leonard, Stephen S.; Castranova, Vince; Chen, Bean T.; Schwegler-Berry, Diane; Hoover, Mark; Piacitelli, Chris; Gaughan, Denise M.

2007-01-01

Firefighting, along with construction, mining and agriculture, ranks among the most dangerous occupations. In addition, the work environment of firefighters is unlike that of any other occupation, not only because of the obvious physical hazards but also due to the respiratory and systemic health hazards of smoke inhalation resulting from combustion. A significant amount of research has been devoted to studying municipal firefighters; however, these studies may not be useful in wildland firefighter exposures, because the two work environments are so different. Not only are wildland firefighters exposed to different combustion products, but their exposure profiles are different. The combustion products wildland firefighters are exposed to can vary greatly in characteristics due to the type and amount of material being burned, soil conditions, temperature and exposure time. Smoke inhalation is one of the greatest concerns for firefighter health and it has been shown that the smoke consists of a large number of particles. These smoke particles contain intermediates of hydrogen, carbon and oxygen free radicals, which may pose a potential health risk. Our investigation looked into the involvement of free radicals in smoke toxicity and the relationship between particle size and radical generation. Samples were collected in discrete aerodynamic particle sizes from a wildfire in Alaska, preserved and then shipped to our laboratory for analysis. Electron spin resonance was used to measure carbon-centered as well as hydroxyl radicals produced by a Fenton-like reaction with wildfire smoke. Further study of reactive oxygen species was conducted using analysis of cellular H 2 O 2 generation, lipid peroxidation of cellular membranes and DNA damage. Results demonstrate that coarse size-range particles contained more carbon radicals per unit mass than the ultrafine particles; however, the ultrafine particles generated more ·OH radicals in the acellular Fenton-like reaction. The

Cytotoxicity evaluation of ceramic particles of different sizes and shapes.

Science.gov (United States)

Yamamoto, Akiko; Honma, Rieko; Sumita, Masae; Hanawa, Takao

2004-02-01

When artificial hip or knee joints are implanted in the human body, they release metallic, ceramic, and polymeric debris into the surrounding tissues. The toxicity of the released particles is of two types: chemical, caused by the released soluble ions and monomers, and mechanical, a result of mechanical stimulation produced by the insoluble particles. In this study, the cytotoxicity of particles of TiO2, Al2O3, ZrO2, Si3N4, and SiC for murine fibroblasts and macrophages were examined to evaluate just their mechanical toxicity because these particles are not expected to release soluble metal ions. Different sizes and shapes of TiO2 particles were used to evaluate the effect of size and shape on particle cytotoxicity. The results suggest that the cytotoxicity of ceramic particles does not depend on their chemical species. Cytotoxicity levels were lower than those of corresponding metal ions, indicating that the mechanical toxicity of particles is lower than the chemical toxicity of released soluble ions and monomers. The differences in size did not affect the mechanical toxicity of these particles. The dendritic particles had a higher cytotoxicity level for macrophages than did spindle and spheric particles. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 244-256, 2004

The influences of ambient particle composition and size on particle infiltration in Los Angeles, CA, residences.

Science.gov (United States)

Sarnat, Stefanie Ebelt; Coull, Brent A; Ruiz, Pablo A; Koutrakis, Petros; Suh, Helen H

2006-02-01

Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH4NO3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (FINF), for fine particles (PM2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO3-]) components, and particle sizes ranging between 0.02 and 10 microm. FINF was highest for BC (median = 0.84) and lowest for NO3- (median = 0.18). The low FINF for NO3- was likely because of volatilization of NO3- particles once indoors, in addition to depositional losses upon building entry. The FINF for PM2.5 (median = 0.48) fell between those for BC and NO3-, reflecting the contributions of both particle components to PM25. FINF varied with particle size, air-exchange rate, and outdoor NO3- concentrations. The FINF for particles between 0.7 and 2 microm in size was considerably lower during periods of high as compared with low outdoor NO3- concentrations, suggesting that outdoor NO3- particles were of this size. This study demonstrates that infiltration of PM2.5 varies by particle component and is lowest for volatile species, such as NH4NO3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas

Influence of high-energy impact on the physical and technical characteristics of coal fuels

Science.gov (United States)

Mal'tsev, L. I.; Belogurova, T. P.; Kravchenko, I. V.

2017-08-01

Currently, in the world's large-scale coal-fired power industry, the combustion of pulverized coal is the most widely spread technology of combusting the coals. In recent years, the micropulverization technology for preparation and combustion of the coal has been developed in this field. As applied to the small-scale power industry, the method of combusting the coal in the form of a coal-water slurry has been explored for years. Fine coal powders are produced and used in the pulverized-coal gasification. Therefore, the coal preparation methods that involve high-dispersion disintegration of coals attract the greatest interest. The article deals with the problems of high-energy impact on the coal during the preparation of pulverized-coal fuels and coal-water slurries, in particular, during the milling of the coal in ball drum mills and the subsequent regrinding in disintegrators or the cavitation treatment of the coal-water slurries. The investigations were conducted using samples of anthracite and lignite from Belovskii open-pit mine (Kuznetsk Basin). It is shown that both the disintegration and the cavitation treatment are efficient methods for controlling the fuel characteristics. Both methods allow increasing the degree of dispersion of the coal. The content of the small-sized particles reground by cavitation considerably exceeds the similar figure obtained using the disintegrator. The specific surface area of the coal is increased by both cavitation and disintegration with the cavitation treatment producing a considerably greater effect. Being subjected to the cavitation treatment, most coal particles assume the form of a split characterized by the thermodynamically nonequilibrium state. Under external action, in particular, of temperature, the morphological structure of such pulverized materials changes faster and, consequently, the combustion of the treated coal should occur more efficiently. The obtained results are explained from the physical point of view.

Toxicogenomic analysis of the particle dose- and size-response relationship of silica particles-induced toxicity in mice

International Nuclear Information System (INIS)

Lu Xiaoyan; Jin Tingting; Jin Yachao; Wu Leihong; Hu Bin; Tian Yu; Fan Xiaohui

2013-01-01

This study investigated the relationship between particle size and toxicity of silica particles (SP) with diameters of 30, 70, and 300 nm, which is essential to the safe design and application of SP. Data obtained from histopathological examinations suggested that SP of these sizes can all induce acute inflammation in the liver. In vivo imaging showed that intravenously administrated SP are mainly present in the liver, spleen and intestinal tract. Interestingly, in gene expression analysis, the cellular response pathways activated in the liver are predominantly conserved independently of particle dose when the same size SP are administered or are conserved independently of particle size, surface area and particle number when nano- or submicro-sized SP are administered at their toxic doses. Meanwhile, integrated analysis of transcriptomics, previous metabonomics and conventional toxicological results support the view that SP can result in inflammatory and oxidative stress, generate mitochondrial dysfunction, and eventually cause hepatocyte necrosis by neutrophil-mediated liver injury. (paper)

Process for heating coal-oil slurries

Science.gov (United States)

Braunlin, W.A.; Gorski, A.; Jaehnig, L.J.; Moskal, C.J.; Naylor, J.D.; Parimi, K.; Ward, J.V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec[sup [minus]1]. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72. 29 figs.

Influence of particle size on physical and sensory attributes of mango pulp powder

Science.gov (United States)

Sharma, M.; Kadam, D. M.; Chadha, S.; Wilson, R. A.; Gupta, R. K.

2013-09-01

The present investigation was aimed to observe the effect of particle size on physical, sensory and thermal properties of foam-mat dried mango pulp powder. Mango pulp of Dussehri variety was foam-mat dried using 3% egg white at 65ºC. Dried foam-mats were pulverized and passed through a sieve shaker for obtaining three grades of powder with 50, 60, and 85 mesh size sieves. The particle size of these samples measured using laser diffraction particle size analyzer ranged from 191.26 to 296.19 μm. The data was analysed statistically using ANOVA of SAS. There was a linear increase in lightness (`L' value) with a decrease in particle size, however, `a' value decreased with a decrease in particle size, indicating the decrease in redness. An increase in bulk density and decrease in water solubility index and water absorption index % were observed with a decrease in particle size. Particle size had a significant effect on sensory parameters. Particle size in the range of 258.01 to 264.60μmwas found most acceptable with respect to sensory characteristics. This finding can be exploited for various commercial applicationswhere powder quality is dependent on the particle size and has foremost priority for end users.

Strategy for determination of an efficient Cochleate particle size.

Science.gov (United States)

Gil, Danay; Bracho, Gustavo; Zayas, Caridad; del Campo, Judith; Acevedo, Reinaldo; Toledo, Arturo; Lastre, Miriam; Pérez, Oliver

2006-04-12

Cochleate structures obtained from the outer membrane of Neisseria meningitidis serotype B have demonstrated to be high immunogenicity when administrated by intramuscular, oral or intranasal routes, and could be used as adjuvant and meningococcal nasal vaccine candidate. Due to the microparticulate nature of Cochleate it is necessary to control the particle size since it capture by cells of the immune system could be affected by this aspect. We combined optic microscopy and immunisation experiments to select the optimum particle size. Six different processes of producing Cochleate obtaining were evaluated and different mechanical stress conditions were carried out to homogenize and modulate the particles size. The more immunogenic particles were selected on the basis of the levels of specific IgA and IgG antibodies induced after intranasal immunisation in mice. The best treatment parameter for mechanical stress of the Cochleate was prolonged treatment with untrasonic low frequency waves.

Highly Dispersed Pseudo-Homogeneous and Heterogeneous Catalysts Synthesized via Inverse Micelle Solutions for the Liquefaction of Coal

Energy Technology Data Exchange (ETDEWEB)

Hampden-Smith, M.; Kawola, J.S.; Martino, A.; Sault, A.G.; Yamanaka, S.A.

1999-01-05

The mission of this project was to use inverse micelle solutions to synthesize nanometer sized metal particles and test the particles as catalysts in the liquefaction of coal and other related reactions. The initial focus of the project was the synthesis of iron based materials in pseudo-homogeneous form. The frost three chapters discuss the synthesis, characterization, and catalyst testing in coal liquefaction and model coal liquefaction reactions of iron based pseudo-homogeneous materials. Later, we became interested in highly dispersed catalysts for coprocessing of coal and plastic waste. Bifunctional catalysts . to hydrogenate the coal and depolymerize the plastic waste are ideal. We began studying, based on our previously devised synthesis strategies, the synthesis of heterogeneous catalysts with a bifunctional nature. In chapter 4, we discuss the fundamental principles in heterogeneous catalysis synthesis with inverse micelle solutions. In chapter 5, we extend the synthesis of chapter 4 to practical systems and use the materials in catalyst testing. Finally in chapter 6, we return to iron and coal liquefaction now studied with the heterogeneous catalysts.

Preparation of gold nanoparticles and determination of their particles size via different methods

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad; Usanase, Gisele [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar [Laboratory of Chemistry and Environmental Chemistry(LCCE), Faculty of Science, Material Science Department, University of Batna, 05000 (Algeria); Fessi, Hatem [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Zine, Nadia [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Agusti, Géraldine [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Errachid, El-Salhi [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Elaissari, Abdelhamid, E-mail: elaissari@lagep.univ-lyon1.fr [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France)

2016-07-15

Graphical abstract: Preparation of gold nanoparticles via NaBH{sub 4} reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH{sub 4} reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH{sub 4}) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

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.

Synthesis of micro-sized polystyrene magnetic particles

International Nuclear Information System (INIS)

Neves, Juliete S.; Suarez, Paulo A.Z.; Umpierre, Alexandre P.; Machado, Fabricio; Souza Junior, Fernando G. de

2011-01-01

The present work illustrates the synthesis of spherical and micro-sized polystyrene magnetic particles by using a water-based suspension polymerization process to incorporate in situ surface modified superparamagnetic Fe 3 O 4 nanoparticles. The crystallite size of Fe 3 O 4 was determined to be equal to 7.7 nm, based on Scherrer's equation and XRD measurement. According to EDX analyses, Fe 3 O 4 / polystyrene nanocomposites particles show strong characteristic peaks Kα and Kβ of iron at the interval from 6.38 KeV to 7.04 KeV with an amount of iron in the samples equal to 98 %, indicating that the inorganic material dispersed in the polystyrene matrix is essentially Fe in the form of iron oxide (Fe 3 O 4 ). The obtained polymeric materials presented good magnetic behavior, indicating that the modified Fe 3 O 4 nanoparticles were successfully dispersed in the polystyrene particles. (author)

Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

Science.gov (United States)

Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

2017-03-01

We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

Characterization of Coal Porosity for Naturally Tectonically Stressed Coals in Huaibei Coal Field, China

Science.gov (United States)

Li, Xiaoshi; Hou, Quanlin; Li, Zhuo; Wei, Mingming

2014-01-01

The enrichment of coalbed methane (CBM) and the outburst of gas in a coal mine are closely related to the nanopore structure of coal. The evolutionary characteristics of 12 coal nanopore structures under different natural deformational mechanisms (brittle and ductile deformation) are studied using a scanning electron microscope (SEM) and low-temperature nitrogen adsorption. The results indicate that there are mainly submicropores (2~5 nm) and supermicropores (coal and mesopores (10~100 nm) and micropores (5~10 nm) in brittle deformed coal. The cumulative pore volume (V) and surface area (S) in brittle deformed coal are smaller than those in ductile deformed coal which indicates more adsorption space for gas. The coal with the smaller pores exhibits a large surface area, and coal with the larger pores exhibits a large volume for a given pore volume. We also found that the relationship between S and V turns from a positive correlation to a negative correlation when S > 4 m2/g, with pore sizes coal. The nanopore structure (coal. PMID:25126601

Effect of dispersed phase particle size on microstructure of cup fracture

International Nuclear Information System (INIS)

Goritskij, V.M.; Guseva, I.A.

1978-01-01

A correlation-regressive analysis has been carried out to reveal the influence of the size and the mean distance between the disperse particles of deposits V(C,N) on the microstructure (size of micropores and cups, density of the cups) of a viscous cup-like fracture of specimens made of 30Kh2NMFA grade steel that has been hardened and annealed. It is shown that micropores develop at relatively large particles of deposits V(C,N) (>=0.04/m). A strong correlation linear connection exists between the size of a disperse particle of deposits V(C,N), the size of micropore and cup. This connection is attributable to the close, pairwise correlative connection between the size of the particle and the micropore, the micropore and the cup

[Emission characteristics of PM10 from coal-fired industrial boiler].

Science.gov (United States)

Li, Chao; Li, Xing-Hua; Duan, Lei; Zhao, Meng; Duan, Jing-Chun; Hao, Ji-Ming

2009-03-15

Through ELPI (electrical low-pressure impactor) based dilution sampling system, the emission characteristics of PM10 and PM2.5 was studied experimentally at the inlet and outlet of dust catchers at eight different coal-fired industrial boilers. Results showed that a peak existed at around 0.12-0.20 microm of particle size for both number size distribution and mass size distribution of PM10 emitted from most of the boilers. Chemical composition analysis indicated that PM2.5 was largely composed of organic carbon, elementary carbon, and sulfate, with mass fraction of 3.7%-21.4%, 4.2%-24.6%, and 1.5%-55.2% respectively. Emission factors of PM10 and PM2.5 measured were 0.13-0.65 kg x t(-1) and 0.08-0.49 kg x t(-1) respectively for grate boiler using raw coal, and 0.24 kg x t(-1) and 0.22 kg x t(-1) for chain-grate boiler using briquette. In comparison, the PM2.5 emission factor of fluidized bed boiler is 1.14 kg x t(-1), much her than that of grate boiler. Due to high coal consumption and low efficiency of dust separator, coal-fired industrial boiler may become the most important source of PM10, and should be preferentially controlled in China.

Acute respiratory effects of the inhalation of coal-dust particles

Energy Technology Data Exchange (ETDEWEB)

McDermott, M

1962-01-01

Volunteers were exposed to 8 to 50 mg/m/sup 3/ (< 7 ..mu..m) coal dust clouds from 10 a.m. to 2 p.m. Controls showed a 10% decrease in airway resistance (R/sub a/) during this time. Those exposed to 8 or 9 mg/m/sup 3/ showed no change in R/sub a/, whereas those exposed to 19, 33, or 50 mg/m/sup 3/ showed increases in R/sub a/ that were correlated with the weight of particles between 3.6 and 7 ..mu..m. There was large individual variation. Increased respiratory rate and dyspnea were measured at heaviest loading. R/sub a/ decreased, but not to normal values, 1 hr after the exposure.

Combinative Particle Size Reduction Technologies for the Production of Drug Nanocrystals

Directory of Open Access Journals (Sweden)

Jaime Salazar

2014-01-01

Full Text Available Nanosizing is a suitable method to enhance the dissolution rate and therefore the bioavailability of poorly soluble drugs. The success of the particle size reduction processes depends on critical factors such as the employed technology, equipment, and drug physicochemical properties. High pressure homogenization and wet bead milling are standard comminution techniques that have been already employed to successfully formulate poorly soluble drugs and bring them to market. However, these techniques have limitations in their particle size reduction performance, such as long production times and the necessity of employing a micronized drug as the starting material. This review article discusses the development of combinative methods, such as the NANOEDGE, H 96, H 69, H 42, and CT technologies. These processes were developed to improve the particle size reduction effectiveness of the standard techniques. These novel technologies can combine bottom-up and/or top-down techniques in a two-step process. The combinative processes lead in general to improved particle size reduction effectiveness. Faster production of drug nanocrystals and smaller final mean particle sizes are among the main advantages. The combinative particle size reduction technologies are very useful formulation tools, and they will continue acquiring importance for the production of drug nanocrystals.

Rock sampling. [method for controlling particle size distribution

Science.gov (United States)

Blum, P. (Inventor)

1971-01-01

A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

Improving the stability of coal slurries: Quarterly progress report for the period Sep. 15, 1986-Dec. 15, 1986. [Adsorption of gum tragacanth on coal particles

Energy Technology Data Exchange (ETDEWEB)

Fogler, H.S.

1986-01-01

The last quarterly progress report focused on the adsorption study of the polystyrene latex spheres with gum tragacanth (GT), and the adsorption mechanism was found to be hydrophobic rather than electrostatic. Also, the effect of the amount of GT adsorbed, the bulk concentration of GT, incubation time and pH on the stability factor was examined, and the results indicated that the conformation of GT on the surface of latex spheres plays an important role in the stabilization. This report presents the results of the coal-water slurries, mainly focusing on the adsorption study of GT by changing pH and ionic strength. It was found from the experiment in which the ionic strength was changed that the adsorption of GT on the coal particles is hindered by the coulombic repulsion between GT and coal. In addition, the experiment in which pH was changed also indicated that the adsorption mechanism is electrostatic in nature. 7 refs., 2 figs.

Studies of particle drying using non-invasive Raman spectrometry and particle size analysis.

Science.gov (United States)

Hamilton, Peter; Littlejohn, David; Nordon, Alison; Sefcik, Jan; Slavin, Paul; Dallin, Paul; Andrews, John

2011-05-21

The evaporation of methanol from needle-shaped particles of cellobiose octaacetate (COA) has been studied directly in a jacketed vacuum drier using in situ measurements by Raman spectrometry. A design of experiments (DoE) approach was used to investigate the effects of three parameters (method of agitation, % solvent loss on drying and jacket temperature), with the intention of minimising the drying time and extent of particle attrition. Drying curves based on Raman signals for methanol and COA in the spectra of the wet particles indicated the end of drying and revealed three stages in the drying process that could be used to monitor the progress of solvent removal in real time. Off-line particle size measurements based on laser diffraction were made to obtain information on the extent of attrition, to compare with the trends revealed by the Raman drying curves. The study demonstrated that non-invasive Raman spectrometry can be used to study the progress of drying during agitation of particles in a vacuum drier, allowing optimisation of operating conditions to minimise attrition and reduce drying times. Although a correlation between particle size and off-line Raman measurements of COA was demonstrated, it was not possible to derive equivalent information from the in situ Raman spectra owing to the greater effects of particle motion or bulk density variations of the particles in the drier.

Report on Seminar on Clean Coal Technology '93; Clean coal technology kokusai seminar hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-11-01

The program of the above clean coal technology (CCT) event is composed of 1) Coal energy be friendly toward the earth, 2) Research on CCT in America (study of coal structure under electron microscope), and 3) Research on CCT in Australia (high intensity combustion of ultrafine coal particles in a clean way). Remarks under item 1) are mentioned below. As for SO{sub 2} emissions base unit, Japan's is 1 at its coal-fired thermal power station while that of America is 7.8. As for the level of SO{sub 2}/NOx reduction attributable to coal utilization technologies, it rises in the order of flue gas desulfurizer-aided pulverized coal combustion, normal pressure fluidized bed combustion, pressurized fluidized bed combustion, integrated coal gasification combined cycle power generation, and integrated coal gasification combined cycle power generation/fuel cell. As for the level of CO2 reduction attributable to power generation efficiency improvement, provided that Japan's average power generation efficiency is 39% and if China's efficiency which is now 28% is improved to be similar to that of Japan, there will be a 40% reduction in CO2 emissions. Under item 2) which involves America's CCT program, reference is made to efforts at eliminating unnecessary part from the catalytic process and at reducing surplus air, to the export of CCT technology, and so forth. Under item 3), it is stated that coal cleaning may govern reaction efficiency in a process of burning coal particles for gasification. (NEDO)

Characterization of spherical core–shell particles by static light scattering. Estimation of the core- and particle-size distributions

International Nuclear Information System (INIS)

Clementi, Luis A.; Vega, Jorge R.; Gugliotta, Luis M.; Quirantes, Arturo

2012-01-01

A numerical method is proposed for the characterization of core–shell spherical particles from static light scattering (SLS) measurements. The method is able to estimate the core size distribution (CSD) and the particle size distribution (PSD), through the following two-step procedure: (i) the estimation of the bivariate core–particle size distribution (C–PSD), by solving a linear ill-conditioned inverse problem through a generalized Tikhonov regularization strategy, and (ii) the calculation of the CSD and the PSD from the estimated C–PSD. First, the method was evaluated on the basis of several simulated examples, with polystyrene–poly(methyl methacrylate) core–shell particles of different CSDs and PSDs. Then, two samples of hematite–Yttrium basic carbonate core–shell particles were successfully characterized. In all analyzed examples, acceptable estimates of the PSD and the average diameter of the CSD were obtained. Based on the single-scattering Mie theory, the proposed method is an effective tool for characterizing core–shell colloidal particles larger than their Rayleigh limits without requiring any a-priori assumption on the shapes of the size distributions. Under such conditions, the PSDs can always be adequately estimated, while acceptable CSD estimates are obtained when the core/shell particles exhibit either a high optical contrast, or a moderate optical contrast but with a high ‘average core diameter’/‘average particle diameter’ ratio. -- Highlights: ► Particles with core–shell morphology are characterized by static light scattering. ► Core size distribution and particle size distribution are successfully estimated. ► Simulated and experimental examples are used to validate the numerical method. ► The positive effect of a large core/shell optical contrast is investigated. ► No a-priori assumption on the shapes of the size distributions is required.

An investigation on characterizing dense coal-water slurry with ultrasound: theoretical and experimental method

Energy Technology Data Exchange (ETDEWEB)

Xue, M.H.; Su, M.X.; Dong, L.L.; Shang, Z.T.; Cai, X.S. [Shanghai University of Science & Technology, Shanghai (China)

2010-07-01

Particle size distribution and concentration in particulate two-phase flow are important parameters in a wide variety of industrial areas. For the purpose of online characterization in dense coal-water slurries, ultrasonic methods have many advantages such as avoiding dilution, the capability for being used in real time, and noninvasive testing, while light-based techniques are not capable of providing information because optical methods often require the slurry to be diluted. In this article, the modified Urick equation including temperature modification, which can be used to determine the concentration by means of the measurement of ultrasonic velocity in a coal-water slurry, is evaluated on the basis of theoretical analysis and experimental study. A combination of the coupled-phase model and the Bouguer-Lambert-Beer law is employed in this work, and the attenuation spectrum is measured within the frequency region from 3 to 12 MHz. Particle size distributions of the coal-water slurry at different volume fractions are obtained with the optimum regularization technique. Therefore, the ultrasonic technique presented in this work brings the possibility of using ultrasound for online measurements of dense slurries.

Theory of flotation of small and medium-size particles

Science.gov (United States)

Derjaguin, B. V.; Dukhin, S. S.

1993-08-01

The paper describes a theory of flotation of small and medium-size particles less than 50μ in radius) when their precipitation on a bubble surface depends more on surface forces than on inertia forces, and deformation of the bubble due to collisions with the particles may be neglected. The approach of the mineral particle to the bubble surface is regarded as taking place in three stages corresponding to movement of the particles through zones 1, 2 and 3. Zone 3 is a liquid wetting layer of such thickness that a positive or negative disjoining pressure arises in this intervening layer between the particle and the bubble. By zone 2 is meant the diffusional boundary layer of the bubble. In zone 1, which comprises the entire liquid outside zone 2, there are no surface forces. Precipitation of the particles is calculated by considering the forces acting in zones 1, 2 and 3. The particles move through zone 1 under the action of gravity and inertia. Analysis of the movement of the particles under the action of these forces gives the critical particle size, below which contact with the bubble surface is impossible, if the surface forces acting in zones 2 and 3 be neglected. The forces acting in zone 2 are ‘diffusio-phoretic’ forces due to the concentration gradient in the diffusional boundary layer. The concentration and electric field intensity distribution in zone 2 is calculated, taking into account ion diffusion to the deformed bubble surface. An examination is made of the ‘equilibrium’ surface forces acting in zone 3 independent of whether the bubble is at rest or in motion. These forces, which determine the behaviour of the thin wetting intervening layer between the bubble and the mineral particle and the height of the force barrier against its rupture, may be represented as results of the disjoining pressure forces acting on various parts of the film. The main components of the disjoining pressure are van der Waals forces, forces of an iono

Thermogravimetric analytical procedures for determining reactivities of chars from New Zealand coals

Energy Technology Data Exchange (ETDEWEB)

Shaw, K.J.; Beamish, B.B.; Rodgers, K.A. [University of Auckland, Auckland (New Zealand). Dept. of Geology

1997-10-22

This paper describes how tightly constrained thermogravimetric experimental procedures (particle size {lt} 212 {mu}m, sample mass 15.5 mg, CO{sub 2} reactant gas, near isothermal conditions) allow the reactivity of chars from high volatile New Zealand coals to be determined to a repeatability of {+-}0.07 h{sup -1} at 900{degree}C and {+-}0.5 h{sup -1} at 1100{degree}C. The procedure also provides proximate analyses information and affords a quick ({lt} 90 min) comparison between different coal types as well as indicating likely operating conditions and problems associated with a particular coal or blend. A clear difference is evident between reactivities of differing New Zealand coal ranks. Between 900 and 1100{degree}C, bituminous coals increase thirtyfold in reactivity compared with fourfold for subbituminous, with the latter being three to five times greater in reactivity at higher temperature.

Fundamental study for improvement of dewatering of fine coal/refuse. Annual report, August 1982-August 1983

Energy Technology Data Exchange (ETDEWEB)

Chiang, S.H.; Klinzing, G.E.; Morsi, B.J.; Tierney, J.W.; Adams, J.; Bhat, N.; Binkley, T.; Chi, S.M.; Kakwani, R.; Qamar, I.

1983-09-01

The overall objective of the study is to seek improved methods of dewatering through a better understanding of the filtration and post-filtration processes. As a first step, efforts have been focused on the mechanism of dewatering in terms of basic properties of coal (and refuse) particles and microstructures of filter cakes, and their relations to filtration rate and final moisture content. Pittsburgh seam-Bruceton Mine coal was used as a base coal with experiments also being conducted with Upper Freeport and Illinois No. 6 coals. During the past year, filter cakes from the above coals with widely varied size ranges were micrographically characterized. The effects of a number of surface active agents and of entrapped air bubbles on the filter cake properties were also studied. A module of the network model for calculating single phase permeabilities was completed and tested. The report is divided into four parts: summary and deliverables; work forecast for the 1983-84; detailed descriptions of technical progress for particle/filter cake characterization; theoretical modeling, and enhanced dewatering methods; and appendices. 11 references, 35 figures, 11 tables.

Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

Energy Technology Data Exchange (ETDEWEB)

Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

2013-08-15

One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

International Nuclear Information System (INIS)

Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S.

2013-08-01

One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

Combustion aerosols from co-firing of coal and solid recovered fuel in a 400 mw pf-fired power plant

DEFF Research Database (Denmark)

Pedersen, Anne Juul; Wu, Hao; Jappe Frandsen, Flemming

2010-01-01

In this work, combustion aerosols (i.e. fine particles fired power plant was sampled with a low-pressure impactor, and analysed by transmission and scanning electron microscopy. The power plant was operated at both dedicated coal combustion conditions...... and under conditions with cofiring of up to 10% (thermal basis) of solid recovered fuel (SRF). The SRFs were characterized by high contents of Cl, Ca, Na and trace metals, while the coal had relatively higher S, Al, Fe and K content. The mass-based particle size distribution of the aerosols was found...... to be bi-modal, with an ultrafine (vaporization) mode centered around 0.1 μm, and a coarser (finefragmentation) mode above 2 μm. Co-firing of SRF tended to increase the formation of ultrafine particles as compared with dedicated coal combustion, while the coarse mode tended to decrease. The increased...

Investigation of Composition of Particle Size in Sediments of Stormwater Sedimentation Tank

Directory of Open Access Journals (Sweden)

Daiva Laučytė

2011-04-01

Full Text Available The main object for the storm water runoff treatment is to remove suspended solids before the storm water runoff is discharged into surface waters. Therefore the sedimentation tank is the most often used treatment facility. In order to optimise the sedimentation, the tendency of particle size distribution in bottom sediments must be known. Two similar size storm water runoff sedimentation tanks in Vilnius city were selected for the analysis of the particle size distribution in sediments. The composite samples of drained storm water runoff sediments were collected at the sedimentation tanks located in the districts of Verkiai and Karoliniskes on the 2nd of June, 2008. The analyses of grain size distribution were performed according the standard ISO/TS 17892-4:2004. The results showed that the particles with the particle size of 1–2 mm were obtained up to 10 m from the inlet and the particles with the size of 0,01–0,05 mm mainly were obtained close to the outlet of sedimentation tank. It is recommended to divide the sedimentation tank in two parts in order to get proper management of sediments: the particles that size is 1–10 mm could be managed as waste from grit chambers and particles of smaller size could be managed as primary sludge.Article in Lithuanian

Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

Science.gov (United States)

Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

2017-11-01

Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Influence of particle size in silo discharge

Directory of Open Access Journals (Sweden)

Gella Diego

2017-01-01

Full Text Available Recently Janda et al. [Phys. Rev. Lett. 108, 248001 (2012] reported an experimental study where it was measured the velocity and volume fraction fields of 1 mm diameter stainless steel beads in the exit of a two-dimensional silo. In that work, they proposed a new expression to predict the flow of granular media in silos which does not explicitly include the particle size as a parameter. Here, we study if effectively, there is not such influence of the particle size in the flux equations as well as investigate any possible effect in the velocity and volume fraction fields. To this end, we have performed high speed motion measurements of these magnitudes in a two-dimensional silo filled with 4 mm diameter beads of stainless steel, the same material than the previous works. A developed tracking program has been implemented to obtain at the same time both, the velocity and volume fraction. The final objective of this work has been to extend and generalize the theoretical framework of Janda et al. for all sizes of particles. We have found that the obtained functionalities are the same than in the 1 mm case, but the exponents and other fitting parameters are different.

Dust generation in powders: Effect of particle size distribution

Directory of Open Access Journals (Sweden)

Chakravarty Somik

2017-01-01

Full Text Available This study explores the relationship between the bulk and grain-scale properties of powders and dust generation. A vortex shaker dustiness tester was used to evaluate 8 calcium carbonate test powders with median particle sizes ranging from 2μm to 136μm. Respirable aerosols released from the powder samples were characterised by their particle number and mass concentrations. All the powder samples were found to release respirable fractions of dust particles which end up decreasing with time. The variation of powder dustiness as a function of the particle size distribution was analysed for the powders, which were classified into three groups based on the fraction of particles within the respirable range. The trends we observe might be due to the interplay of several mechanisms like de-agglomeration and attrition and their relative importance.

Synthesis and characterization of magnetic and non-magnetic core-shell polyepoxide micrometer-sized particles of narrow size distribution.

Science.gov (United States)

Omer-Mizrahi, Melany; Margel, Shlomo

2009-01-15

Core polystyrene microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2-methoxy ethanol. Uniform polyglycidyl methacrylate/polystyrene core-shell micrometer-sized particles were prepared by emulsion polymerization at 73 degrees C of glycidyl methacrylate in the presence of the core polystyrene microspheres. Core-shell particles with different properties (size, surface morphology and composition) have been prepared by changing various parameters belonging to the above seeded emulsion polymerization process, e.g., volumes of the monomer glycidyl methacrylate and the crosslinker monomer ethylene glycol dimethacrylate. Magnetic Fe(3)O(4)/polyglycidyl methacrylate/polystyrene micrometer-sized particles were prepared by coating the former core-shell particles with magnetite nanoparticles via a nucleation and growth mechanism. Characterization of the various particles has been accomplished by routine methods such as light microscopy, SEM, FTIR, BET and magnetic measurements.

Automatic particle-size analysis of HTGR nuclear fuel microspheres

International Nuclear Information System (INIS)

Mack, J.E.

1977-01-01

An automatic particle-size analyzer (PSA) has been developed at ORNL for measuring and counting samples of nuclear fuel microspheres in the diameter range of 300 to 1000 μm at rates in excess of 2000 particles per minute, requiring no sample preparation. A light blockage technique is used in conjunction with a particle singularizer. Each particle in the sample is sized, and the information is accumulated by a multi-channel pulse height analyzer. The data are then transferred automatically to a computer for calculation of mean diameter, standard deviation, kurtosis, and skewness of the distribution. Entering the sample weight and pre-coating data permits calculation of particle density and the mean coating thickness and density. Following this nondestructive analysis, the sample is collected and returned to the process line or used for further analysis. The device has potential as an on-line quality control device in processes dealing with spherical or near-spherical particles where rapid analysis is required for process control

Determination of Cd, Hg, Pb and Tl in coal and coal fly ash slurries using electrothermal vaporization inductively coupled plasma mass spectrometry and isotopic dilution

Energy Technology Data Exchange (ETDEWEB)

Maia, S.M.; Pozebon, D.; Curtius, A.J. [Univ. Federal de Santa Catarina, Florianopolis, SC (Brazil)

2003-07-01

A method has been investigated for the determination of Cd, Hg, Pb and Tl in coal and in coal fly ash, using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry and isotope dilution. The slurry, 25 mg ml{sup -1}, was prepared by mixing the powdered sample (less than or equal to 36 - 45 mm) with acid solutions (nitric acid for coal and nitric and hydrofluoric acids for coal fly ash) and submitting the mixture to an ultrasonic agitation, letting it stand afterwards in a water bath at 60{sup o}C for 2 h. An ultrasonic probe was used to homogenize the slurry in the autosampler cup just before its introduction into the graphite tube. The best conditions were determined regarding analyte sensitivity, furnace temperature program, amount of modifier, acid concentration, gas flow rate and particle size. For Hg, the pyrolysis stage was omitted and a low vaporization temperature was used (450 - 1000{sup o}C); the residual matrix was eliminated in the first step of the following cycle. The modifiers used were: Pd for Cd and Tl; Au, Ir or Pd for Hg; Ir or Pd for Pb. The accuracy of the method was checked by analyzing six certified coal reference materials (SARM 20, SARM 19, BCR No. 40, BCR No. 180, BCR No. 181 and NIST 1630a) and one certified coal fly ash (NIST 1633b). With one exception (Hg in BCR No. 180), the found concentrations were typically within 95% confidence interval of the certified values, or close enough to the recommended values, as long as the samples were ground to a small enough particle size. The limits of detection were typically around 0.08 {mu}g g{sup -1}, 0.03 {mu}g g{sup -1}, 1 {mu}g g{sup -1} and 0.02 {mu}g g{sup -1} for Cd, Hg, Pb and Tl, respectively. The precision was also adequate with relative standard deviations of usually < 5%.

Dependence of Pyrolysis Rate of Coal on Temperature

Directory of Open Access Journals (Sweden)

Slyusarskiy Konstantin V.

2015-01-01

Full Text Available Pyrolysis process of coal has been researched to define kinetic constants which can be used for design and optimization of different processes of fuel transformation. The article considers anthracite powders and bituminous coal of Krasnogorsky mine with the use of non-isothermal thermogravimetric analysis with mass spectrometry. Spectroscanning microscopy and laser diffraction for definition of sizes and forms of particles distribution has been done. Other parameters – carbon content, ash and volatiles, density and moisture have been defined by standard methods. Energy of activation and pre-exponent with the use of models of Freedman, Starink and distributed activation energy model (DAEM, and also relative deviation of design data from experimental ones have been designed. The results of the analysis have shown the important influence of volatiles content and coal transformation degree on maximum reaction rate. Energy activation values received with the help of DAEM model are higher than with Freedman and Starink models. Process of pyrolysis of bituminous coal has a big rate in comparison with anthracite, and is better described by the above-mentioned models.

Light absorption by coated nano-sized carbonaceous particles

Science.gov (United States)

Gangl, Martin; Kocifaj, Miroslav; Videen, Gorden; Horvath, Helmuth

The optical properties of strongly absorbing soot particles coated by transparent material are investigated experimentally and described by several modeling approaches. Soot is produced by spark discharge and passed through a Sinclair-La Mer generator where non-absorbing carnauba wax is condensed onto it to obtain internal soot-wax mixtures in a controlled way. Measurements of the extinction and volume scattering coefficient show an amplification of absorption by a factor of approximately 1.8. This behavior was described by different approaches of internally mixed materials for the modal diameters of the measured size distributions: concentric-sphere model, effective medium approximations and heterogeneous ellipsoids. The concentric-sphere model describes the absorption increase quantitatively; and hence, it is chosen to be applied to the entire particle population in the size distribution. The growth of the soot particles by condensing wax is described by a simplified growth model to estimate the different contributions of several soot particle diameters to the overall absorption cross-section.

Photometric imaging in particle size measurement and surface visualization.

Science.gov (United States)

Sandler, Niklas

2011-09-30

The aim of this paper is to give an insight into photometric particle sizing approaches, which differ from the typical particle size measurement of dispersed particles. These approaches can often be advantageous especially for samples that are moist or cohesive, when dispersion of particles is difficult or sometimes impossible. The main focus of this paper is in the use of photometric stereo imaging. The technique allows the reconstruction of three-dimensional images of objects using multiple light sources in illumination. The use of photometric techniques is demonstrated in at-line measurement of granules and on-line measurement during granulation and dry milling. Also, surface visualization and roughness measurements are briefly discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

Particle Size Distributions in Chondritic Meteorites: Evidence for Pre-Planetesimal Histories

Science.gov (United States)

Simon, J. I.; Cuzzi, J. N.; McCain, K. A.; Cato, M. J.; Christoffersen, P. A.; Fisher, K. R.; Srinivasan, P.; Tait, A. W.; Olson, D. M.; Scargle, J. D.

2018-01-01

Magnesium-rich silicate chondrules and calcium-, aluminum-rich refractory inclusions (CAIs) are fundamental components of primitive chondritic meteorites. It has been suggested that concentration of these early-formed particles by nebular sorting processes may lead to accretion of planetesimals, the planetary bodies that represent the building blocks of the terrestrial planets. In this case, the size distributions of the particles may constrain the accretion process. Here we present new particle size distribution data for Northwest Africa 5717, a primitive ordinary chondrite (ungrouped 3.05) and the well-known carbonaceous chondrite Allende (CV3). Instead of the relatively narrow size distributions obtained in previous studies (Ebel et al., 2016; Friedrich et al., 2015; Paque and Cuzzi, 1997, and references therein), we observed broad size distributions for all particle types in both meteorites. Detailed microscopic image analysis of Allende shows differences in the size distributions of chondrule subtypes, but collectively these subpopulations comprise a composite "chondrule" size distribution that is similar to the broad size distribution found for CAIs. Also, we find accretionary 'dust' rims on only a subset (approximately 15-20 percent) of the chondrules contained in Allende, which indicates that subpopulations of chondrules experienced distinct histories prior to planetary accretion. For the rimmed subset, we find positive correlation between rim thickness and chondrule size. The remarkable similarity between the size distributions of various subgroups of particles, both with and without fine grained rims, implies a common size sorting process. Chondrite classification schemes, astrophysical disk models that predict a narrow chondrule size population and/or a common localized formation event, and conventional particle analysis methods must all be critically reevaluated. We support the idea that distinct "lithologies" in NWA 5717 are nebular aggregates of

U-Mo Alloy Powder Obtained Through Selective Hydriding. Particle Size Control

International Nuclear Information System (INIS)

Balart, S.N.; Bruzzoni, P.; Granovsky, M.S.

2002-01-01

Hydride-dehydride methods to obtain U-Mo alloy powder for high-density fuel elements have been successfully tested by different authors. One of these methods is the selective hydriding of the α phase (HSα). In the HSα method, a key step is the partial decomposition of the γ phase (retained by quenching) to α phase and an enriched γ phase or U 2 Mo. This transformation starts mainly at grain boundaries. Subsequent hydrogenation of this material leads to selective hydriding of the α phase, embrittlement and intergranular fracture. According to this picture, the particle size of the final product should be related to the γ grain size of the starting alloy. The feasibility of controlling the particle size of the product by changing the γ grain size of the starting alloy is currently investigated. In this work an U-7 wt% Mo alloy was subjected to various heat treatments in order to obtain different grain sizes. The results on the powder particle size distribution after applying the HSα method to these samples show that there is a strong correlation between the original γ grain size and the particle size distribution of the powder. (author)

Control over particle size distribution by autoclaving poloxamer-stabilized trimyristin nanodispersions

DEFF Research Database (Denmark)

Göke, Katrin; Roese, Elin; Arnold, Andreas

2016-01-01

Lipid nanoparticles are under investigation as delivery systems for poorly water-soluble drugs. The particle size in these dispersions strongly influences important pharmaceutical properties like biodistribution and drug loading capacity; it should be below 500 nm for direct injection into the bl......Lipid nanoparticles are under investigation as delivery systems for poorly water-soluble drugs. The particle size in these dispersions strongly influences important pharmaceutical properties like biodistribution and drug loading capacity; it should be below 500 nm for direct injection...... treatment thus seems to be a promising approach to achieve the desired narrow particle size distribution of such dispersions. Related to the lipid content, suspension particles needed more emulsifier for stabilization than emulsion droplets, and smaller particles more than larger ones....

Particle number size distributions in urban air before and after volatilisation

Directory of Open Access Journals (Sweden)

W. Birmili

2010-05-01

Full Text Available Aerosol particle number size distributions (size range 0.003–10 μm in the urban atmosphere of Augsburg (Germany were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm⁻³, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass.

Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C, allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R²=0.9 suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could

ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS

Energy Technology Data Exchange (ETDEWEB)

E. James Davis

1999-12-18

The objective of this research was to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. The specific objectives were: Design and develop a scaleable electrophoresis apparatus to clarify suspensions of colloidal coal and clay particles; Demonstrate the separation process using polluted waste water from the coal-washing facilities at the coal-fired power plants in Centralia, WA; Develop a mathematical model of the process to predict the rate of clarification and the suspension electrical properties needed for scale up.

Particle size, magnetic field, and blood velocity effects on particle retention in magnetic drug targeting.

Science.gov (United States)

Cherry, Erica M; Maxim, Peter G; Eaton, John K

2010-01-01

A physics-based model of a general magnetic drug targeting (MDT) system was developed with the goal of realizing the practical limitations of MDT when electromagnets are the source of the magnetic field. The simulation tracks magnetic particles subject to gravity, drag force, magnetic force, and hydrodynamic lift in specified flow fields and external magnetic field distributions. A model problem was analyzed to determine the effect of drug particle size, blood flow velocity, and magnetic field gradient strength on efficiency in holding particles stationary in a laminar Poiseuille flow modeling blood flow in a medium-sized artery. It was found that particle retention rate increased with increasing particle diameter and magnetic field gradient strength and decreased with increasing bulk flow velocity. The results suggest that MDT systems with electromagnets are unsuitable for use in small arteries because it is difficult to control particles smaller than about 20 microm in diameter.

Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

DEFF Research Database (Denmark)

Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt

1997-01-01

Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

Metal uptake by corn grown on media treated with particle-size fractionated biosolids

Energy Technology Data Exchange (ETDEWEB)

Chen, Weiping [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States)], E-mail: chenweip@yahoo.com.cn; Chang, Andrew C.; Wu, Laosheng [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States); Zhang, Yongsong [School of Environmental and Natural Resources Sciences, Zhejiang University, Hangzhou, Zhejiang, 31009 (China)

2008-03-15

Particle-size of biosolids may affect plant uptake of heavy metals when the biosolids are land applied. In this study, corn (Zea mays L.) was grown on sand media treated with biosolids to study how particle-size of biosolids affected the plant uptake of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Two biosolids, the Nu-Earth biosolids and the Los Angeles biosolids, of dissimilar surface morphology were utilized. The former exhibited a porous and spongy structure and had considerably greater specific surface area than that of the latter, which was granular and blocky. The specific surface area of the Los Angeles biosolids was inversely proportional to its particle-size, while that of Nu-Earth biosolids did not change significantly with particle-size. For each biosolid, the metal concentrations were not affected by particle sizes. The biomass yields of plants grown on the treated media increased as the biosolid particle-size decreased, indicating that plant uptake of nutrients from biosolids was dependent on interactions at the root-biosolids interface. The effect of particle-size on a metal's availability to plants was element-specific. The uptake rate of Cd, Zn, Cu, and Ni was correlated with the surface area of the particles, i.e., smaller particles having higher specific area provided greater root-biosolids contact and resulted in enhanced uptake of Cd and Zn and slightly less increased uptake of Cu and Ni. The particle morphology of biosolids had limited influence on the plant tissue concentrations of Cr and Pb. For both types of biosolids, total metal uptake increased as biosolid particle-size decreased. Our research indicates that biosolid particle-size distribution plays a deciding role in plant uptake of heavy metals when they are land applied.

Stability of MC Carbide Particles Size in Creep Resisting Steels

Directory of Open Access Journals (Sweden)

Vodopivec, F.

2006-01-01

Full Text Available Theoretical analysis of the dependence microstructure creep rate. Discussion on the effects of carbide particles size and their distribution on the base of accelerated creep tests on a steel X20CrMoV121 tempered at 800 °C. Analysis of the stability of carbide particles size in terms of free energy of formation of the compound. Explanation of the different effect of VC and NbC particles on accelerated creep rate.

A low-cost, high-magnification imaging system for particle sizing applications

International Nuclear Information System (INIS)

Tipnis, Tanmay J; Lawson, Nicholas J; Tatam, Ralph P

2014-01-01

A low-cost imaging system for high magnification and high resolution was developed as an alternative to long-working-distance microscope-based systems, primarily for particle sizing applications. The imaging optics, comprising an inverted fixed focus lens coupled to a microscope objective, were able to provide a working distance of approximately 50 mm. The system magnification could be changed by using an appropriate microscope objective. Particle sizing was achieved using shadow-based techniques with the backlight illumination provided by a pulsed light-emitting diode light source. The images were analysed using commercial sizing software which gave the particle sizes and their distribution. A range of particles, from 6 to 8 µm to over 100 µm, was successfully measured with a minimum spatial resolution of approximately 2.5 µm. This system allowed measurement of a wide range of particles at a lower cost and improved operator safety without disturbing the flow. (technical design note)

Determination of particle size distribution of salt crystals in aqueous slurries

International Nuclear Information System (INIS)

Miller, A.G.

1977-10-01

A method for determining particle size distribution of water-soluble crystals in aqueous slurries is described. The salt slurries, containing sodium salts of predominantly nitrate, but also nitrite, sulfate, phosphate, aluminates, carbonate, and hydroxide, occur in radioactive, concentrated chemical waste from the reprocessing of nuclear fuel elements. The method involves separating the crystals from the aqueous phase, drying them, and then dispersing the crystals in a nonaqueous medium based on nitroethane. Ultrasonic treatment is important in dispersing the sample into its fundamental crystals. The dispersed crystals are sieved into appropriate size ranges for counting with a HIAC brand particle counter. A preponderance of very fine particles in a slurry was found to increase the difficulty of effecting complete dispersion of the crystals because of the tendency to retain traces of aqueous mother liquor. Traces of moisture produce agglomerates of crystals, the extent of agglomeration being dependent on the amount of moisture present. The procedure is applicable to particles within the 2 to 600 μm size range of the HIAC particle counter. The procedure provides an effective means for measuring particle size distribution of crystals in aqueous salt slurries even when most crystals are less than 10 μm in size. 19 figures

Thermal and particle size distribution effects on the ferromagnetic resonance in magnetic fluids

International Nuclear Information System (INIS)

Marin, C.N.

2006-01-01

Thermal and particle size distribution effects on the ferromagnetic resonance of magnetic fluids were theoretically investigated, assuming negligible interparticle interactions and neglecting the viscosity of the carrier liquid. The model is based on the usual approach for the ferromagnetic resonance description of single-domain magnetic particle systems, which was amended in order to take into account the finite particle size effect, the particle size distribution and the orientation mobility of the particles within the magnetic fluid. Under these circumstances the shape of the resonance line, the resonance field and the line width are found to be strongly affected by the temperature and by the particle size distribution of magnetic fluids

Picobubble enhanced column flotation of fine coal

Energy Technology Data Exchange (ETDEWEB)

Tao, D.; Yu, S.; Parekh, B.K. [University of Kentucky, Lexington, KY (United States). Mining Engineering

2006-07-01

The purpose is to study the effectiveness of picobubbles in the column flotation of -28 mesh fine coal particles. A flotation column with a picobubble generator was developed and tested for enhancing the recovery of ultrafine coal particles. The picobubble generator was designed using the hydrodynamic cavitation principle. A metallurgical and a steam coal were tested in the apparatus. The results show that the use of picobubbles in a 2in. flotation column increased the recovery of fine coal by 10 to 30%. The recovery rate varied with feed rate, collector dosage, and other column conditions. 40 refs., 8 figs., 2 tabs.

Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

Energy Technology Data Exchange (ETDEWEB)

Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul Gabriel; McKenzie, Bonnie Beth; Bufford, Daniel Charles; Hall, Aaron Christopher.

2014-09-01

The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and

A new mathematical model for coal flotation kinetics

OpenAIRE

Guerrero-Pérez, Juan Sebastián; Barraza-Burgos, Juan Manuel

2017-01-01

Abstract This study describes the development and formulation of a novel mathematical model for coal flotation kinetic. The flotation rate was considered as a function of chemical, operating and petrographic parameters for a global flotation order n. The equation for flotation rate was obtained by dimensional analysis using the Rayleigh method. It shows the dependency of flotation kinetic on operating parameters, such as air velocity and particle size; chemical parameters, such as reagents do...

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

Simultaneous velocity and particle size measurement in two phase flows by Laser Anemometry

Science.gov (United States)

Ungut, A.; Yule, A. J.; Taylor, D. S.; Chigier, N. A.

1978-01-01

A technique for particle size measurement by using Laser Doppler Anemometry is discussed. An additional gate photomultiplier has been introduced at right angles to the optical axis in order to select only those particles passing through the central region of the measurement control volume. Particle sizing measurements have been made in sprays of glass particles using the modified Laser Anemometry system. Measurements in fuel sprays are also reported and compared with the results obtained by a photographic technique. The application of the particle sizing technique to opaque particles is investigated and suitable optical arrangements are suggested. Light scattering characteristics of Laser Anemometry systems for different optical geometries are calculated to select the optimum optical arrangement for the particle sizing measurements.

Feed particle size evaluation: conventional approach versus digital holography based image analysis

Directory of Open Access Journals (Sweden)

Vittorio Dell’Orto

2010-01-01

Full Text Available The aim of this study was to evaluate the application of image analysis approach based on digital holography in defining particle size in comparison with the sieve shaker method (sieving method as reference method. For this purpose ground corn meal was analyzed by a sieve shaker Retsch VS 1000 and by image analysis approach based on digital holography. Particle size from digital holography were compared with results obtained by screen (sieving analysis for each of size classes by a cumulative distribution plot. Comparison between particle size values obtained by sieving method and image analysis indicated that values were comparable in term of particle size information, introducing a potential application for digital holography and image analysis in feed industry.

Discrete element method modeling of the triboelectric charging of polyethylene particles: Can particle size distribution and segregation reduce the charging?

International Nuclear Information System (INIS)

Konopka, Ladislav; Kosek, Juraj

2015-01-01

Polyethylene particles of various sizes are present in industrial gas-dispersion reactors and downstream processing units. The contact of the particles with a device wall as well as the mutual particle collisions cause electrons on the particle surface to redistribute in the system. The undesirable triboelectric charging results in several operational problems and safety risks in industrial systems, for example in the fluidized-bed polymerization reactor. We studied the charging of polyethylene particles caused by the particle-particle interactions in gas. Our model employs the Discrete Element Method (DEM) describing the particle dynamics and incorporates the ‘Trapped Electron Approach’ as the physical basis for the considered charging mechanism. The model predicts the particle charge distribution for systems with various particle size distributions and various level of segregation. Simulation results are in a qualitative agreement with experimental observations of similar particulate systems specifically in two aspects: 1) Big particles tend to gain positive charge and small particles the negative one. 2) The wider the particle size distribution is, the more pronounced is the charging process. Our results suggest that not only the size distribution, but also the effect of the spatial segregation of the polyethylene particles significantly influence the resulting charge distribution ‘generated’ in the system. The level of particle segregation as well as the particle size distribution of polyethylene particles can be in practice adjusted by the choice of supported catalysts, by the conditions in the fluidized-bed polymerization reactor and by the fluid dynamics. We also attempt to predict how the reactor temperature affects the triboelectric charging of particles. (paper)

Size exclusion chromatography with superficially porous particles.

Science.gov (United States)

Schure, Mark R; Moran, Robert E

2017-01-13

A comparison is made using size-exclusion chromatography (SEC) of synthetic polymers between fully porous particles (FPPs) and superficially porous particles (SPPs) with similar particle diameters, pore sizes and equal flow rates. Polystyrene molecular weight standards with a mobile phase of tetrahydrofuran are utilized for all measurements conducted with standard HPLC equipment. Although it is traditionally thought that larger pore volume is thermodynamically advantageous in SEC for better separations, SPPs have kinetic advantages and these will be shown to compensate for the loss in pore volume compared to FPPs. The comparison metrics include the elution range (smaller with SPPs), the plate count (larger for SPPs), the rate production of theoretical plates (larger for SPPs) and the specific resolution (larger with FPPs). Advantages to using SPPs for SEC are discussed such that similar separations can be conducted faster using SPPs. SEC using SPPs offers similar peak capacities to that using FPPs but with faster operation. This also suggests that SEC conducted in the second dimension of a two-dimensional liquid chromatograph may benefit with reduced run time and with equivalently reduced peak width making SPPs advantageous for sampling the first dimension by the second dimension separator. Additional advantages are discussed for biomolecules along with a discussion of optimization criteria for size-based separations. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of maize flour particle size on gluten-free breadmaking.

Science.gov (United States)

de la Hera, Esther; Talegón, María; Caballero, Pedro; Gómez, Manuel

2013-03-15

Maize, one of the suitable grains for coeliac consumption, is, together with rice, the most cultivated cereal in the world. However, the inclusion of maize flour in gluten-free bread is a minority and studies are scarce. This paper analyses the influence of different maize flour types and their particle sizes on the quality of two types of bread without gluten (80% and 110% water in the formulation) obtained from them. We also analysed the microstructure of the dough and its behaviour during the fermentation. Finer flours had a lower dough development during fermentation in all cases. Among the different types of flour, those whose microstructure revealed compact particles were those which had higher specific bread volume, especially when the particle size was greater. Among the formulations, the dough with more water gave breads with higher specific volume, an effect that was more important in more compact flours. The higher volume breads had lower values of hardness and resilience. The type of corn flour and mainly its particle size influence significantly the dough development of gluten-free bread during fermentation and therefore the final volume and texture of the breads obtained. The flours having coarser particle size are the most suitable for making gluten-free maize bread. © 2012 Society of Chemical Industry.

Viscous properties of ferrofluids containing both micrometer-size magnetic particles and fine needle-like particles

Energy Technology Data Exchange (ETDEWEB)

Ido, Yasushi, E-mail: ido.yasushi@nitech.ac.jp [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Nishida, Hitoshi [Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, 13 Hongo-cho, Toyama (Japan); Iwamoto, Yuhiro [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Yokoyama, Hiroki [KYB Corporation, 2-4-1 Hamamatsu-cho, Minato-ku, Tokyo (Japan)

2017-06-01

Ferrofluids containing both micrometer-size spherical magnetic particles and nanometer-size needle-like nonmagnetic hematite particles were newly produced. Average length of long axis of the needle-like nonmagnetic particles was 194 nm and the aspect ratio was 8.3. Shear stress and viscosity were measured using the rheometer with the additional equipment for viscosity measurements in the presence of magnetic field. When the total volume fraction of particles in the fluid is constant (0.30), there is the specific mixing ratio of the particles to increase viscosity of the fluid drastically in the absence of magnetic field due to the percolation phenomenon. The fluid of the specific mixing ratio shows solid-like behavior even in the absence of magnetic field. Mixing the needle-like nonmagnetic particles causes strong yield stress and strong viscous force in the presence of magnetic field. - Highlights: • Viscous properties of new magnetic functional fluids were studied experimentally. • The new fluids contain spherical magnetic particles and needle-like particles. • Percolation occurs in the fluid of specific mixing ratio of particles without field. • The fluid of the specific mixing ratio behaves like solid without field. • Mixing needle-like particles causes strong yield stress of the fluid in the field.

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.

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.

Kinetics of coal combustion: Part 3, Mechanisms and kinetics of char combustion

Energy Technology Data Exchange (ETDEWEB)

Gavalas, G. R.; Flagan, R. C. [California Inst. of Tech., Pasadena, CA (USA)

1988-09-01

This report summarizes a three-year research program aimed at developing this level of understanding of char combustion through a combination of detailed analysis of chars as produced during devolatilization and as they evolve during oxidation, and theoretical studies of the porous microstructures and of pore diffusion and reaction within the coal particles. A small number of coals have been studied in detail, namely a HVA bituminous (PSOC 1451), a sub-bituminous (PSOC 1488), and a lignite (PSOC 1443). Chars have been generated from size-classified samples of these coals by pyrolysis in an inert atmosphere in a drop tube furnace. The chars were then characterized both chemically and physically. Subsequent oxidation studies were performed on these chars. 42 refs., 54 figs., 4 tabs.

Micrometer-scale 3-D shape characterization of eight cements: Particle shape and cement chemistry, and the effect of particle shape on laser diffraction particle size measurement

International Nuclear Information System (INIS)

Erdogan, S.T.; Nie, X.; Stutzman, P.E.; Garboczi, E.J.

2010-01-01

Eight different portland cements were imaged on a synchrotron beam line at Brookhaven National Laboratory using X-ray microcomputed tomography at a voxel size of about 1 μm per cubic voxel edge. The particles ranged in size roughly between 10 μm and 100 μm. The shape and size of individual particles were computationally analyzed using spherical harmonic analysis. The particle shape difference between cements was small but significant, as judged by several different quantitative shape measures, including the particle length, width, and thickness distributions. It was found that the average shape of cement particles was closely correlated with the volume fraction of C 3 S (alite) and C 2 S (belite) making up the cement powder. It is shown that the non-spherical particle shape of the cements strongly influence laser diffraction results, at least in the sieve size range of 20 μm to 38 μm. Since laser diffraction particle size measurement is being increasingly used by the cement industry, while cement chemistry is always a main factor in cement production, these results could have important implications for how this kind of particle size measurement should be understood and used in the cement industry.

Mineral identification in Colombian coals using Moessbauer spectroscopy and X-ray diffraction

International Nuclear Information System (INIS)

Fajardo, M.; Mojica, J.; Barraza, J.; Perez Alcazar, G.A.; Tabares, J.A.

1999-01-01

Minerals were identified in three Colombian coal samples from the Southwest of the country using Moessbauer spectroscopy and X-ray diffraction. Original and sink separated coal fractions of specific gravity 1.40 and 1.60 with particle size less than 600 μm were used in the study. Using Moessbauer spectroscopy, the minerals identified in the original coal samples were pyrite jarosite, ankerite, illite and ferrous sulfate, whereas by means of X-ray diffraction, minerals identified were kaolinite, quartz, pyrite, and jarosite. Differences in mineral composition were found in the original and sink separated fractions using both techniques. Moessbauer spectra show that the mineral phases in low concentrations such as illite, ankerite and ferrous sulfate do not always appear in the spectra of sink coals, despite of those minerals occurring in the original coal, due to the fact that they are associated with the organic matter and not liberated in the grinding process. X-ray results show that the peak intensity grows as the specific gravity is increased indicating that the density separation method could be an effective process to clean coal

Ultrasound Assisted Particle Size Control by Continuous Seed Generation and Batch Growth

OpenAIRE

Jordens, Jeroen; Canini, Enio; Gielen, Bjorn; Van Gerven, Tom; Braeken, Leen

2017-01-01

Controlling particle size is essential for crystal quality in the chemical and pharmaceutical industry. Several articles illustrate the potential of ultrasound to tune this particle size during the crystallization process. This paper investigates how ultrasound can control the particle size distribution (PSD) of acetaminophen crystals by continuous seed generation in a tubular crystallizer followed by batch growth. It is demonstrated that the supersaturation ratio at which ultrasound starts s...

Neutron activation analysis of size-separated airborne dust particles, (2)

International Nuclear Information System (INIS)

Aoki, Atsushi; Ishii, Taka; Tomiyama, Tsuyoshi; Yamamoto, Isao.

1976-01-01

The size distribution of the component element concentration in particle floating matters contained in the atmosphere is related closely to atmospheric pollution. In this paper, the results of the neutron activation analysis and the measurement of size distribution of component element concentration are reported, which were carried out in Minami-ku, Kyoto, in May and November, 1975, by collecting airbone dust with Andersen air samples. The activation of samples was carried out with the research reactor in Kyoto University. The gamma-ray spectra of the samples were measured with a Ge(Li) semiconductor detector. The size distributions of Al, Sc, Th and Ti showed the similar pattern. The concentration of Zn was abnormally high as compared with that in other districts, and it is related to the local industry in this district. The size distribution of airborne dust usually follows the logarithmic normal distribution when it is not affected by atmospheric pollution. Accordingly, the size distribution of the concentration also follows the same distribution. The accumulated percentages of the concentrations of Al, Sc and Th fall on the same straight line, and it means that these elements were contained in the same particles as the components. Also it was decided that the particles of Al, Sc, Th, Fe and Ti were soil particles. (Kako, I.)

The immersion freezing behavior of size-segregated soot and kaolinite particles

Science.gov (United States)

Hartmann, S.; Augustin, S.; Clauss, T.; Niedermeier, D.; Raddatz, M.; Wex, H.; Shaw, R. A.; Stratmann, F.

2011-12-01

Heterogeneous ice nucleation plays a crucial role for ice formation in mixed-phase and cirrus clouds and has an important impact on precipitation formation, global radiation balances, and therefore Earth's climate (Cantrell and Heymsfield, 2005). Mineral dust and soot particles are found to be a major component of ice crystal residues (e.g., Pratt et al., 2009) so these substances are potential sources of atmospheric ice nuclei (IN). Experimental studies investigating the immersion freezing behavior of size-segregated soot and kaolinite particles conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS) are presented. In our measurements only one aerosol particle is immersed in an air suspended water droplet which can trigger ice nucleation. The method facilitates very precise examinations with respect to temperature, ice nucleation time and ice nucleus size. Considering laboratory studies, the picture of the IN ability of soot particles is quite heterogeneous. Our studies show that submicron flame, spark soot particles and optionally coated with sulfuric acid to simulate chemically aging do not act as IN at temperatures higher than homogeneous freezing taking place. Therefore soot particles might not be an important source of IN for immersion freezing in the atmosphere. In contrast, kaolinite being representative for natural mineral dust with a well known composition and structure is found to be very active in forming ice for all freezing modes (e.g., Mason and Maybank, 1958). Analyzing the immersion freezing behavior of different sized kaolinite particles (300, 500 and 700 nm in diameter) the size effect was clearly observed, i.e. the ice fraction (number of frozen droplets per total number) scales with particle surface, i.e. the larger the ice nucleus surface the higher the ice fraction. The slope of the logarithm of the ice fraction as function of temperature is similar for all particle sizes investigated and fits very well with the results of L�

Experimental studies on the group ignition of a cloud of coal particles: Volume 2, Pyrolysis and ignition modeling. Final report, August 15, 1988--October 15, 1991

Energy Technology Data Exchange (ETDEWEB)

Annamalai, K.; Ryan, W.

1992-01-01

The primary objectives of this work are to formulate a model to simulate transient coal pyrolysis, ignition, and combustion of a cloud of coal particles and to compare results of the program with those reported in the literature elsewhere.