Numerical modelling of emissions of nitrogen oxides in solid fuel combustion.

Science.gov (United States)

Bešenić, Tibor; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

2018-06-01

Among the combustion products, nitrogen oxides are one of the main contributors to a negative impact on the environment, participating in harmful processes such as tropospheric ozone and acid rains production. The main source of emissions of nitrogen oxides is the human combustion of fossil fuels. Their formation models are investigated and implemented with the goal of obtaining a tool for studying the nitrogen-containing pollutant production. In this work, numerical simulation of solid fuel combustion was carried out on a three-dimensional model of a drop tube furnace by using the commercial software FIRE. It was used for simulating turbulent fluid flow and temperature field, concentrations of the reactants and products, as well as the fluid-particles interaction by numerically solving the integro-differential equations describing these processes. Chemical reactions mechanisms for the formation of nitrogen oxides were implemented by the user functions. To achieve reasonable calculation times for running the simulations, as well as efficient coupling with the turbulent mixing process, the nitrogen scheme is limited to sufficiently few homogeneous reactions and species. Turbulent fluctuations that affect the reaction rates of nitrogen oxides' concentration are modelled by probability density function approach. Results of the implemented model for nitrogen oxides' formation from coal and biomass are compared to the experimental data. Temperature, burnout and nitrogen oxides' concentration profiles are compared, showing satisfactory agreement. The new model allows the simulation of pollutant formation in the real-world applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Production of nanocrystalline metal powders via combustion reaction synthesis

Science.gov (United States)

Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.; Kim, Jin Yong

2017-10-31

Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace

Science.gov (United States)

Karim, Md. Rezwanul; Naser, Jamal

2017-06-01

Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.

New paradigm for simplified combustion modeling of energetic solids: Branched chain gas reaction

Energy Technology Data Exchange (ETDEWEB)

Brewster, M.Q.; Ward, M.J. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States)

1997-09-01

Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT {much_gt} 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT {much_lt} 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity {sigma}{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and {sigma}{sub p}(T{sub o},P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for {sigma}{sub p}(T{sub o},P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.

Managing ash from the combustion of solid waste

International Nuclear Information System (INIS)

Hauser, R.

1992-01-01

This paper reports that with millions of tons of refuse being combusted each year, increasing concern over the environment impact of the residue produced has caused both regulators and the resource recovery industry to address the technical and regulatory issues relating to the safe handling and disposal of ash. The basic issue concerning solid waste combustion ash management in this country is how, based on past, recent, and ongoing scientific research, solid waste combustion ash should be handled. Typically, refuse contains approximately 20 to 25 percent residue, which is collected either on grates at the bottom of the combustion chamber or filtered from the exhaust gases by the air pollution control equipment. The fly ash component of the total residue stream is between 10 and 30 percent of the total residue while the bottom ash content ranges from 70 to 90 percent of the total weight, depending upon the air pollution control equipment utilized, especially acid gas scrubbing equipment

Improved Economic Performance of Municipal Solid Waste Combustion Plants by Model Based Combustion Control

NARCIS (Netherlands)

Leskens, M.

2013-01-01

The combustion of municipal solid waste (MSW) is used for its inertisation, reduction of its volume and the conversion of its energy content into heat and/or electricity. Operation and control of modern large scale MSW combustion (MSWC) plants is determined by economic and environmental objectives

The Evaluation of Solid Wastes Reduction with Combustion System in the Combustion Chamber

International Nuclear Information System (INIS)

Prayitno; Sukosrono

2007-01-01

The evaluation of solid wastes reduction with combustion system is used for weight reduction factor. The evaluation was done design system of combustion chamber furnace and the experiment was done by burning a certain weight of paper, cloth, plastic and rubber in the combustion chamber. The evaluation of paper wastes, the ratio of wastes (paper, cloth, plastic and rubber) against the factor of weight reduction (%) were investigated. The condition was dimension of combustion chamber furnace = 0.6 X 0.9 X 1.20 X 1 m with combustion chamber and gas chamber and reached at the wastes = 2.500 gram, oxygen pressure 0.5 Bar, wastes ratio : paper : cloth : plastic : rubber = 55 : 10 : 30 : 5, the reduction factor = 6.36 %. (author)

Twenty-fifth symposium (international) on combustion

International Nuclear Information System (INIS)

Anon.

1994-01-01

Approximately two-thirds of the papers presented at this conference are contained in this volume. The other one-third appear in special issues of ''Combustion and Flame'', Vol. 99, 1994 and Vol. 100, 1995. Papers are divided into the following sections: Supersonic combustion; Detonations and explosions; Internal combustion engines; Practical aspects of combustion; Incineration and wastes; Sprays and droplet combustion; Coal and organic solids combustion; Soot and polycyclic aromatic hydrocarbons; Reaction kinetics; NO x ; Turbulent flames; Turbulent combustion; Laminar flames; Flame spread, fire and halogenated fire suppressants; Global environmental effects; Ignition; Two-phase combustion; Solid propellant combustion; Materials synthesis; Microgravity; and Experimental diagnostics. Papers have been processed separately for inclusion on the data base

Chemical analysis of solid residue from liquid and solid fuel combustion: Method development and validation

Energy Technology Data Exchange (ETDEWEB)

Trkmic, M. [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecturek Zagreb (Croatia); Curkovic, L. [University of Zagreb, Faculty of Chemical Engineering and Technology, Zagreb (Croatia); Asperger, D. [HEP-Proizvodnja, Thermal Power Plant Department, Zagreb (Croatia)

2012-06-15

This paper deals with the development and validation of methods for identifying the composition of solid residue after liquid and solid fuel combustion in thermal power plant furnaces. The methods were developed for energy dispersive X-ray fluorescence (EDXRF) spectrometer analysis. Due to the fuels used, the different composition and the location of creation of solid residue, it was necessary to develop two methods. The first method is used for identifying solid residue composition after fuel oil combustion (Method 1), while the second method is used for identifying solid residue composition after the combustion of solid fuels, i. e. coal (Method 2). Method calibration was performed on sets of 12 (Method 1) and 6 (Method 2) certified reference materials (CRM). CRMs and analysis test samples were prepared in pellet form using hydraulic press. For the purpose of method validation the linearity, accuracy, precision and specificity were determined, and the measurement uncertainty of methods for each analyte separately was assessed. The methods were applied in the analysis of real furnace residue samples. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Combustion chamber for solid and liquid waste

Energy Technology Data Exchange (ETDEWEB)

Vcelak, L.; Kocica, J.; Trnobransky, K.; Hrubes, J. (VSCHT, Prague (Czechoslovakia))

1989-04-01

Describes combustion chamber incorporated in a new boiler manufactured by Elitex of Kdyne to burn waste products and occasionally liquid and solid waste from neighboring industries. It can handle all kinds of solids (paper, plastics, textiles, rubber, household waste) and liquids (volatile and non-volatile, zinc, chromium, etc.) and uses coal as a fuel additive. Its heat output is 3 MW, it can burn 1220 kg/h of coal (without waste, calorific value 11.76 MJ/kg) or 500 kg/h of coal (as fuel additive, calorific value 11.76 MJ/kg) or 285 kg/h of solid waste (calorific value 20.8 MJ/kg). Efficiency is 75%, capacity is 103 m{sup 3} and flame temperature is 1,310 C. Individual components are designed for manufacture in small engineering workshops with basic equipment. A disk absorber with alkaline filling is fitted for removal of harmful substances arising when PVC or tires are combusted.

Apparatus and method for solid fuel chemical looping combustion

Science.gov (United States)

Siriwardane, Ranjani V; Weber, Justin M

2015-04-14

The disclosure provides an apparatus and method utilizing fuel reactor comprised of a fuel section, an oxygen carrier section, and a porous divider separating the fuel section and the oxygen carrier section. The porous divider allows fluid communication between the fuel section and the oxygen carrier section while preventing the migration of solids of a particular size. Maintaining particle segregation between the oxygen carrier section and the fuel section during solid fuel gasification and combustion processes allows gases generated in either section to participate in necessary reactions while greatly mitigating issues associated with mixture of the oxygen carrier with char or ash products. The apparatus and method may be utilized with an oxygen uncoupling oxygen carrier such as CuO, Mn.sub.3O.sub.4, or Co.sub.3O.sub.4, or utilized with a CO/H.sub.2 reducing oxygen carrier such as Fe.sub.2O.sub.3.

Synthesising and comparing electrical properties of NTC thermistors prepared from nano powder and solid state reaction

International Nuclear Information System (INIS)

Azad, N.; Ghanbari Shohany, B.; Hosseini, S. M.; Kompany, A.

2011-01-01

In this research, NTC thermistors with composition of NiMn 2-x Co x O 4 (x = 0.4, 0.8, 1.2, 1.6) prepared by two methods: solid state reaction and sol-gel (gel-combustion). The average particle size was monitored and structure of the calcinated powders have been investigated using x-ray diffraction and tunneling electron microscopy techniques. The average particle size was estimated to be about 65 nm with the cubic and cubic + tetragonal phases for low and high cobalt concentrations, respectively. The grain size of samples verifies with scanning electron microscopy images. Upon increasing the cobalt fraction, the grain size of samples increases from about 2μm to a few μm in size. The electrical properties of these thermistors depend on the grain size. The grain size of samples made from sol-gel is smaller than from solid state reaction under the same condition. For longer sintering time of the samples prepared by gel-combustion method, the grain size was increased then the electrical parameters of nano powder improved and we obtain better results than the samples prepared from solid state reaction.

Adiabatic flame temperature of sodium combustion and sodium-water reaction

International Nuclear Information System (INIS)

Okano, Y.; Yamaguchi, A.

2001-01-01

In this paper, background information of sodium fire and sodium-water reaction accidents of LMFBR (liquid metal fast breeder reactor) is mentioned at first. Next, numerical analysis method of GENESYS is described in detail. Next, adiabatic flame temperature and composition of sodium combustion are analyzed, and affect of reactant composition, such oxygen and moisture, is discussed. Finally, adiabatic reaction zone temperature and composition of sodium-water reaction are calculated, and affects of reactant composition, sodium vaporization, and pressure are stated. Chemical equilibrium calculation program for generic chemical system (GENESYS) is developed in this study for the research on adiabatic flame temperature of sodium combustion and adiabatic reaction zone temperature of sodium-water reaction. The maximum flame temperature of the sodium combustion is 1,950 K at the standard atmospheric condition, and is not affected by the existence of moisture. The main reaction product is Na 2 O (l) , and in combustion in moist air, with NaOH (g) . The maximum reaction zone temperature of the sodium-water reaction is 1,600 K, and increases with the system pressure. The main products are NaOH (g) , NaOH (l) and H2 (g) . Sodium evaporation should be considered in the cases of sodium-rich and high pressure above 10 bar

Scale Effects on Solid Rocket Combustion Instability Behaviour

OpenAIRE

David R. Greatrix

2011-01-01

The ability to understand and predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. A numerical model incorporating pertinent elements, such as a representative transient, frequency-dependent combusti...

Pollutants generated by the combustion of solid biomass fuels

CERN Document Server

Jones, Jenny M; Ma, Lin; Williams, Alan; Pourkashanian, Mohamed

2014-01-01

This book considers the pollutants formed by the combustion of solid biomass fuels. The availability and potential use of solid biofuels is first discussed because this is the key to the development of biomass as a source of energy.This is followed by details of the methods used for characterisation of biomass and their classification.The various steps in the combustion mechanisms are given together with a compilation of the kinetic data. The chemical mechanisms for the formation of the pollutants: NOx, smoke and unburned hydrocarbons, SOx, Cl compounds, and particulate metal aerosols

Reaction and diffusion in turbulent combustion

Energy Technology Data Exchange (ETDEWEB)

Pope, S.B. [Mechanical and Aerospace Engineering, Ithaca, NY (United States)

1993-12-01

The motivation for this project is the need to obtain a better quantitative understanding of the technologically-important phenomenon of turbulent combustion. In nearly all applications in which fuel is burned-for example, fossil-fuel power plants, furnaces, gas-turbines and internal-combustion engines-the combustion takes place in a turbulent flow. Designers continually demand more quantitative information about this phenomenon-in the form of turbulent combustion models-so that they can design equipment with increased efficiency and decreased environmental impact. For some time the PI has been developing a class of turbulent combustion models known as PDF methods. These methods have the important virtue that both convection and reaction can be treated without turbulence-modelling assumptions. However, a mixing model is required to account for the effects of molecular diffusion. Currently, the available mixing models are known to have some significant defects. The major motivation of the project is to seek a better understanding of molecular diffusion in turbulent reactive flows, and hence to develop a better mixing model.

Gas-phase reactions at combustion and gasification

International Nuclear Information System (INIS)

Hupa, M.; Kilpinen, P.; Chowdhury, K.; Brink, A.; Mueller, C.

1995-01-01

Formation and destruction of gaseous nitrogen pollutants at combustion (NO x , N 2 O) and gasification (NH 3 , HCN) are studied based on detailed chemical kinetic modelling and experiments in laboratory reactors. During 1994 the following topics have been studied: (a) nitrogen reactions in pressurized combustion processes (in co-operation with the LIEKKI projects 202 and 204), (b) NO x reduction by staging techniques in CO 2 , rich combustion processes, (c) HCN reactions at pyrolysis, (d) formation of soot precursors in a blast furnace (in co-operation with the SULA project 103) (e) incorporation of better NO x description into furnace models, (in co-operation with the LIEKKI project Y01). NH 3 conversion to N 2 in gasification product gases, (in co-operation with the LIEKKI project 203). In this report, some results of the items (a-c) will be presented. The results of items (d-f) are described in the reports by the co-operation projects. (author)

Post-combustion carbon capture - solid sorbents and membranes

Energy Technology Data Exchange (ETDEWEB)

Davidson, R.M.

2009-01-15

This report follows on from that on solvent scrubbing for post-combustion carbon capture from coal-fired power plants by considering the use of solid sorbents and membranes instead of solvents. First, mesoporous and microporous adsorbents are discussed: carbon-based adsorbents, zeolites, hydrotalcites and porous crystals. Attempts have been made to improve the performance of the porous adsorbent by functionalising them with nitrogen groups and specifically, amine groups to react with CO{sub 2} and thus enhance the physical adsorption properties. Dry, regenerable solid sorbents have attracted a good deal of research. Most of the work has been on the carbonation/calcination cycle of natural limestone but there have also been studies of other calcium-based sorbents and alkali metal-based sorbents. Membranes have also been studied as potential post-combustion capture devices. Finally, techno-economic studies predicting the economic performance of solid sorbents and membranes are discussed. 340 refs., 21 figs., 8 tabs.

Development of a high-pressure compaction system for non-combustible solid waste

International Nuclear Information System (INIS)

Yogo, S.; Hata, T.; Torita, K.; Yamamoto, K.; Karita, Y.

1989-01-01

In recent years, nuclear power plants in Japan have been in search of a means to reduce the volume of non-combustible solid wastes and therefore the application of a high-pressure compaction system has been in demand. Most non-combustible solid wastes have been packed in 200-litre drums for storage and the situation requires a high-pressure compaction system designed exclusively for 200-litre drums. The authors have developed a high-pressure compaction system which compresses 200-litre drums filled with non-combustible solid wastes and packs them into new woo-litre drums efficiently. This paper reports the outline of this high-pressure compaction system and the results of the full-scale verification tests

Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

Energy Technology Data Exchange (ETDEWEB)

J. Helble; Clara Smith; David Miller

2009-08-31

The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

Effect of Chamber Pressurization Rate on Combustion and Propagation of Solid Propellant Cracks

Science.gov (United States)

Yuan, Wei-Lan; Wei, Shen; Yuan, Shu-Shen

2002-01-01

area of the propellant grain satisfies the designed value. But cracks in propellant grain can be generated during manufacture, storage, handing and so on. The cracks can provide additional surface area for combustion. The additional combustion may significantly deviate the performance of the rocket motor from the designed conditions, even lead to explosive catastrophe. Therefore a thorough study on the combustion, propagation and fracture of solid propellant cracks must be conducted. This paper takes an isolated propellant crack as the object and studies the effect of chamber pressurization rate on the combustion, propagation and fracture of the crack by experiment and theoretical calculation. deformable, the burning inside a solid propellant crack is a coupling of solid mechanics and combustion dynamics. In this paper, a theoretical model describing the combustion, propagation and fracture of the crack was formulated and solved numerically. The interaction of structural deformation and combustion process was included in the theoretical model. The conservation equations for compressible fluid flow, the equation of state for perfect gas, the heat conducting equation for the solid-phase, constitutive equation for propellant, J-integral fracture criterion and so on are used in the model. The convective burning inside the crack and the propagation and fracture of the crack were numerically studied by solving the set of nonlinear, inhomogeneous gas-phase governing equations and solid-phase equations. On the other hand, the combustion experiments for propellant specimens with a precut crack were conducted by RTR system. Predicted results are in good agreement with experimental data, which validates the reasonableness of the theoretical model. Both theoretical and experimental results indicate that the chamber pressurization rate has strong effects on the convective burning in the crack, crack fracture initiation and fracture pattern.

Combustion of metal agglomerates in a solid rocket core flow

Science.gov (United States)

Maggi, Filippo; Dossi, Stefano; DeLuca, Luigi T.

2013-12-01

The need for access to space may require the use of solid propellants. High thrust and density are appealing features for different applications, spanning from boosting phase to other service applications (separation, de-orbiting, orbit insertion). Aluminum is widely used as a fuel in composite solid rocket motors because metal oxidation increases enthalpy release in combustion chamber and grants higher specific impulse. Combustion process of metal particles is complex and involves aggregation, agglomeration and evolution of reacting particulate inside the core flow of the rocket. It is always stated that residence time should be enough in order to grant complete metal oxidation but agglomerate initial size, rocket grain geometry, burning rate, and other factors have to be reconsidered. New space missions may not require large rocket systems and metal combustion efficiency becomes potentially a key issue to understand whether solid propulsion embodies a viable solution or liquid/hybrid systems are better. A simple model for metal combustion is set up in this paper. Metal particles are represented as single drops trailed by the core flow and reacted according to Beckstead's model. The fluid dynamics is inviscid, incompressible, 1D. The paper presents parametric computations on ideal single-size particles as well as on experimental agglomerate populations as a function of operating rocket conditions and geometries.

Sulfur Release from Cement Raw Materials during Solid Fuel Combustion

DEFF Research Database (Denmark)

Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter

2011-01-01

During combustion of solid fuels in the material inlet end of cement rotary kilns, local reducing conditions can occur and cause decomposition of sulfates from cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2 concentration, which may cause...... deposit formation in the kiln system. SO2 release from cement raw materials during combustion of solid fuels has been studied experimentally in a high temperature rotary drum. The fuels were tire rubber, pine wood, petcoke, sewage sludge, and polypropylene. The SO2 release from the raw materials...

Synthesis of functional materials in combustion reactions

Science.gov (United States)

Zhuravlev, V. D.; Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

2015-12-01

The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating-reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al2O3, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO2, and manganites, cobaltites, and aluminates of rare earth elements.

A mathematical model of combustion kinetics of municipal solid ...

African Journals Online (AJOL)

Municipal Solid Waste has become a serious environmental problem troubling many cities. In this paper, a mathematical model of combustion kinetics of municipal solid waste with focus on plastic waste was studied. An analytical solution is obtained for the model. From the numerical simulation, it is observed that the ...

Post combustion carbon capture - solid sorbents and membranes

Energy Technology Data Exchange (ETDEWEB)

Davidson, R.M. [IEA Clean Coal Centre, London (United Kingdom)

2009-04-15

This report follows on from that on solvent scrubbing for post-combustion carbon capture from coal-fired power plants by considering the use of solid sorbents and membranes instead of solvents. First, mesoporous and microporous adsorbents are discussed: carbon-based adsorbents, zeolites, hydrotalcites and porous crystals. Attempts have been made to improve the performance of the porous adsorbent by functionalising them with nitrogen groups and specifically, amine groups to react with CO{sub 2} and thus enhance the physical adsorption properties. Dry, regenerable solid sorbents have attracted a good deal of research. Most of the work has been on the carbonation/calcination cycle of natural limestone but there have also been studies of other calcium-based sorbents and alkali metal-based sorbents. Membranes have also been studied as potential post-combustion capture devices. Finally, techno-economic studies predicting the economic performance of solid sorbents and membranes are discussed. The report is available from IEA Clean Coal Centre as report no. CCC/144. See Coal Abstracts entry April 2009 00406. 340 refs., 21 figs., 8 tabs.

Optimization of combustion process for radiation-treated solid fuels in dust state

International Nuclear Information System (INIS)

Askarova, A.S.; Bajdullaeva, G.E.

1997-01-01

Computation experiment on combustion of solid radiation-treated fuel in burning chamber of boiler at Pavlodar thermal electric plant is carried out. Velocity, temperature distribution and concentration of combustion products by height of chamber are received. Analysis of received results shows that radiation treatment of fuels exerts substantial effect on egress parameters of thermal electric plant. It is shown, that radiation treatment allows to improve effectiveness of boiler device and reduce of harmful substances discharge in atmosphere. Results of conducted numerical experiments allow to create complete methods of solid fuel combustion with high moisture and ashiness

Unburned carbon in combustion residues from mainly solid biofuels

Energy Technology Data Exchange (ETDEWEB)

Bjurstroem H; Lind B; Lagerkvist A

2012-02-15

Unburned carbon in 21 combustion residues from solid biofuels is investigated using several methods of analysis (a.o. LOI and TOC), as well as micro-Raman spectroscopy. The results are used to discuss the distribution of unburned carbon in the residues from the different combustion plants and its nature (organic or elemental). The consequences of the elemental nature of carbon for environmental properties of the residue are noted

State of art in incineration technology of radioactive combustible solid wastes

International Nuclear Information System (INIS)

Karita, Yoichi

1984-01-01

The features of incineration treatment as the method of treating radioactive wastes are the effect of volume reduction and inorganic stabilization (change to ash). The process of incineration treatment is roughly divided into dry process and wet process. But that in practical use is dry incineration by excess air combustion or suppressed combustion. The important things in incineration techniques are the techniques of exhaust gas treatment as well as combustion techniques. In Europe and USA, incineration has been practiced in laboratories and reprocessing plants for low level combustible solids, but the example of application in nuclear power stations is few. In Japan, though the fundamental techniques are based on the introduction from Europe, the incineration treatment of combustible solids has been carried out in laboratories, reprocessing plants, nuclear fuel production facilities and also nuclear power stations. The techniques of solidifying ash by incineration and the techniques of incinerating spent ion exchange resin are actively developed, and the development of the treatment of radioactive wastes in the lump including incineration also is in progress. (Kako, I.)

Chemical looping combustion: A new low-dioxin energy conversion technology.

Science.gov (United States)

Hua, Xiuning; Wang, Wei

2015-06-01

Dioxin production is a worldwide concern because of its persistence and carcinogenic, teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction, pyrolysis gas oxidized by seven common oxygen carriers, namely, CuO, NiO, CaSO4, CoO, Fe2O3, Mn3O4, and FeTiO3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers (CuO, NiO, Fe2O3, and FeTiO3), the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste. Copyright © 2015. Published by Elsevier B.V.

Combustion kinetics and reaction pathways

Energy Technology Data Exchange (ETDEWEB)

Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

1993-12-01

This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.

Controllable Solid Propulsion Combustion and Acoustic Knowledge Base Improvements

Science.gov (United States)

McCauley, Rachel; Fischbach, Sean; Fredrick, Robert

2012-01-01

Controllable solid propulsion systems have distinctive combustion and acoustic environments that require enhanced testing and analysis techniques to progress this new technology from development to production. In a hot gas valve actuating system, the movement of the pintle through the hot gas exhibits complex acoustic disturbances and flow characteristics that can amplify induced pressure loads that can damage or detonate the rocket motor. The geometry of a controllable solid propulsion gas chamber can set up unique unsteady flow which can feed acoustic oscillations patterns that require characterization. Research in this area aids in the understanding of how best to design, test, and analyze future controllable solid rocket motors using the lessons learned from past government programs as well as university research and testing. This survey paper will give the reader a better understanding of the potentially amplifying affects propagated by a controllable solid rocket motor system and the knowledge of the tools current available to address these acoustic disturbances in a preliminary design. Finally the paper will supply lessons learned from past experiences which will allow the reader to come away with understanding of what steps need to be taken when developing a controllable solid rocket propulsion system. The focus of this survey will be on testing and analysis work published by solid rocket programs and from combustion and acoustic books, conference papers, journal articles, and additionally from subject matter experts dealing currently with controllable solid rocket acoustic analysis.

Superheated fuel injection for combustion of liquid-solid slurries

Science.gov (United States)

Robben, F.A.

1984-10-19

A method and device are claimed for obtaining, upon injection, flash evaporation of a liquid in a slurry fuel to aid in ignition and combustion. The device is particularly beneficial for use of coal-water slurry fuels in internal combustion engines such as diesel engines and gas turbines, and in external combustion devices such as boilers and furnaces. The slurry fuel is heated under pressure to near critical temperature in an injector accumulator, where the pressure is sufficiently high to prevent boiling. After injection into a combustion chamber, the water temperature will be well above boiling point at a reduced pressure in the combustion chamber, and flash boiling will preferentially take place at solid-liquid surfaces, resulting in the shattering of water droplets and the subsequent separation of the water from coal particles. This prevents the agglomeration of the coal particles during the subsequent ignition and combustion process, and reduces the energy required to evaporate the water and to heat the coal particles to ignition temperature. The overall effect will be to accelerate the ignition and combustion rates, and to reduce the size of the ash particles formed from the coal. 2 figs., 2 tabs.

Combustion characteristics and influential factors of isooctane active-thermal atmosphere combustion assisted by two-stage reaction of n-heptane

Energy Technology Data Exchange (ETDEWEB)

Lu, Xingcai; Ji, Libin; Ma, Junjun; Zhou, Xiaoxin; Huang, Zhen [Key Lab. for Power Machinery and Engineering of MOE, Shanghai Jiao Tong University, 200240 Shanghai (China)

2011-02-15

This paper presents an experimental study on the isooctane active-thermal atmosphere combustion (ATAC) which is assisted by two-stage reaction of n-heptane. The active-thermal atmosphere is created by low- and high-temperature reactions of n-heptane which is injected at intake port, and isooctane is directly injected into combustion chamber near the top dead center. The effects of isooctane injection timing, active-thermal atmosphere intensity, overall equivalence ratio, and premixed ratio on combustion characteristics and emissions are investigated. The experimental results reveal that, the isooctane ignition and combustion can be classified to thermal atmosphere combustion, active atmosphere combustion, and active-thermal atmosphere combustion respectively according to the extent of n-heptane oxidation as well as effects of isooctane quenching and charge cooling. n-Heptane equivalence ratio, isooctane equivalence ratio and isooctane delivery advance angle are major control parameters. In one combustion cycle, the isooctane ignited and burned after those of n-heptane, and then this combustion phenomenon can also be named as dual-fuel sequential combustion (DFSC). The ignition timing of the overall combustion event is mainly determined by n-heptane equivalence ratio and can be controlled in flexibility by simultaneously adjusting isooctane equivalence ratio. The isooctane ignition regime, overall thermal efficiency, and NO{sub x} emissions show strong sensitivity to the fuel delivery advance angle between 20 CA BTDC and 25 CA BTDC. (author)

Through-furnace for burning solid organic substances

International Nuclear Information System (INIS)

Kemmler, G.; Schlich, E.

1984-01-01

The through-furnace for burning radio-active organic solid waste consists of a reaction pipe heated from the outside, an input device and an output device. A solid pump is used as the input device, which has a common longitudinal axis with the reaction pipe. The reaction pipe is widened in the transport direction of the combustion pipe, where the angle between the longitudinal axis and the pipe wall is 0.5 to 5 0 . The pipe wall is wholely or partially permeable to gas. The thermal treatment of the solid organic substances can occur by combustion or by pyrohydrolysis or pyrolysis in the through-furnace. (orig./HP) [de

Structure of Partially Premixed Flames and Advanced Solid Propellants

National Research Council Canada - National Science Library

Branch, Melvyn

1998-01-01

The combustion of solid rocket propellants of advanced energetic materials involves a complex process of decomposition and condensed phase reactions in the solid propellant, gaseous flame reactions...

Numerical Simulation of Hydrogen Combustion: Global Reaction Model and Validation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yun [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an (China); Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY (United States); Liu, Yinhe, E-mail: yinheliu@mail.xjtu.edu.cn [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an (China)

2017-11-20

Due to the complexity of modeling the combustion process in nuclear power plants, the global mechanisms are preferred for numerical simulation. To quickly perform the highly resolved simulations with limited processing resources of large-scale hydrogen combustion, a method based on thermal theory was developed to obtain kinetic parameters of global reaction mechanism of hydrogen–air combustion in a wide range. The calculated kinetic parameters at lower hydrogen concentration (C{sub hydrogen} < 20%) were validated against the results obtained from experimental measurements in a container and combustion test facility. In addition, the numerical data by the global mechanism (C{sub hydrogen} > 20%) were compared with the results by detailed mechanism. Good agreement between the model prediction and the experimental data was achieved, and the comparison between simulation results by the detailed mechanism and the global reaction mechanism show that the present calculated global mechanism has excellent predictable capabilities for a wide range of hydrogen–air mixtures.

Numerical Simulation of Hydrogen Combustion: Global Reaction Model and Validation

International Nuclear Information System (INIS)

Zhang, Yun; Liu, Yinhe

2017-01-01

Due to the complexity of modeling the combustion process in nuclear power plants, the global mechanisms are preferred for numerical simulation. To quickly perform the highly resolved simulations with limited processing resources of large-scale hydrogen combustion, a method based on thermal theory was developed to obtain kinetic parameters of global reaction mechanism of hydrogen–air combustion in a wide range. The calculated kinetic parameters at lower hydrogen concentration (C hydrogen < 20%) were validated against the results obtained from experimental measurements in a container and combustion test facility. In addition, the numerical data by the global mechanism (C hydrogen > 20%) were compared with the results by detailed mechanism. Good agreement between the model prediction and the experimental data was achieved, and the comparison between simulation results by the detailed mechanism and the global reaction mechanism show that the present calculated global mechanism has excellent predictable capabilities for a wide range of hydrogen–air mixtures.

Study of combustion properties of a solid propellant by highly time-resolved passive FTIR

Energy Technology Data Exchange (ETDEWEB)

Zhang, Liming; Zhang, Lin; Li, Yan; Liu, Bingping; Wang, Junde [Laboratory of Advanced Spectroscopy, Nanjing University of Science and Technology, Nanjing 210014 (China)

2006-10-15

With a time resolution of 0.125 s and a spectral resolution of 4 cm{sup -1}, emission spectra of the combustion process of a solid propellant were recorded by highly time-resolved passive FTIR. Some gaseous combustion products, such as H{sub 2}O, CO, CO{sub 2}, NO and HCl, were distinguished by the characteristic emission band of each molecule. The equation for flame temperature calculation based on the diatomic molecule emission fine structure theory was improved through judicious utilization of the spectral running number 'm' which makes the temperature measurement simpler and faster. Some combustion information of the solid propellant had been given including the characteristic spectral profile, the distribution of the absolute spectral energy, the distribution of the combustion flame temperature, and the concentration distributions of HCl and NO versus burning time. The results will provide theoretical and experimental bases for improving the formula and raising combustion efficiency of solid propellant, and developing the design of rocket motor, infrared guidance and antiguidance systems. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Scale effects on solid rocket combustion instability behaviour

Energy Technology Data Exchange (ETDEWEB)

Greatrix, D. R. [Ryerson University, Department of Aerospace Engineering, Toronto, Ontario (Canada)

2011-07-01

The ability to understand and predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. A numerical model incorporating pertinent elements, such as a representative transient, frequency-dependent combustion response to pressure wave activity above the burning propellant surface, is applied to the investigation of scale effects (motor size, i.e., grain length and internal port diameter) on influencing instability-related behaviour in a cylindrical-grain motor. The results of this investigation reveal that the motor's size has a significant influence on transient pressure wave magnitude and structure, and on the appearance and magnitude of an associated base pressure rise. (author)

Scale Effects on Solid Rocket Combustion Instability Behaviour

Directory of Open Access Journals (Sweden)

David R. Greatrix

2011-01-01

Full Text Available The ability to understand and predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. A numerical model incorporating pertinent elements, such as a representative transient, frequency-dependent combustion response to pressure wave activity above the burning propellant surface, is applied to the investigation of scale effects (motor size, i.e., grain length and internal port diameter on influencing instability-related behaviour in a cylindrical-grain motor. The results of this investigation reveal that the motor’s size has a significant influence on transient pressure wave magnitude and structure, and on the appearance and magnitude of an associated base pressure rise.

Combustion Characteristics of Chlorine-Free Solid Fuel Produced from Municipal Solid Waste by Hydrothermal Processing

Directory of Open Access Journals (Sweden)

Kunio Yoshikawa

2012-11-01

Full Text Available An experimental study on converting municipal solid waste (MSW into chlorine-free solid fuel using a combination of hydrothermal processing and water-washing has been performed. After the product was extracted from the reactor, water-washing experiments were then conducted to obtain chlorine-free products with less than 3000 ppm total chlorine content. A series of combustion experiments were then performed for the products before and after the washing process to determine the chlorine content in the exhaust gas and those left in the ash after the combustion process at a certain temperature. A series of thermogravimetric analyses were also conducted to compare the combustion characteristics of the products before and after the washing process. Due to the loss of ash and some volatile matter after washing process, there were increases in the fixed carbon content and the heating value of the product. Considering the possible chlorine emission, the washing process after the hydrothermal treatment should be necessary only if the furnace temperature is more than 800 °C.

Combustion flame-plasma hybrid reactor systems, and chemical reactant sources

Science.gov (United States)

Kong, Peter C

2013-11-26

Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.

Study of PAH emission from the solid fuels combustion in residential furnaces

International Nuclear Information System (INIS)

Kakareka, Sergey V.; Kukharchyk, Tamara I.; Khomich, Valery S.

2005-01-01

The procedure for and results of a test study of polycyclic aromatic hydrocarbon (PAH) emission from a few types of solid fuels combustion in residential furnaces of various designs typical for Belarus are discussed. Greatest levels of PAH emission were detected from domestic wastes and wood waste combustion. Lowest levels of PAH emission are from peat briquette combustion. It was found that PAH concentration in off-gases from firewood combustion also varies significantly depending on the type of wood: the highest values of PAH are typical for waste gases from birch firewood combustion in comparison with pine firewood combustion. Draft PAH emission factors are proposed with intended application for emission inventory of such installations

Investigation on the co-combustion of oil shale and municipal solid waste by using thermogravimetric analysis

International Nuclear Information System (INIS)

Fan, Yunlong; Yu, Zhaosheng; Fang, Shiwen; Lin, Yan; Lin, Yousheng; Liao, Yanfen; Ma, Xiaoqian

2016-01-01

Highlights: • Co-combustion of oil shale with municipal solid waste created significant changes. • Blending with municipal solid wastes could improve the combustion performance. • 10–30% of oil shale in the blends could be determined as the optimum ratio range. • Activation energy were calculated by the conversion rate and different proportion. - Abstract: The aim of this study is trying to reveal the thermal characteristics and kinetics of oil shale, municipal solid waste and their blends in the combustion process which are needed for efficient utilization. The combustion experiment is carried out in a thermogravimetric simultaneous thermal analyzer, where the temperature ranged from 110 °C to 900 °C at three different heating rates as 10 °C/min, 20 °C/min and 30 °C/min. Their kinetics were studied by Ozawa–Flynn–Wall and Friedmen methods. According to the data analysis, combustion characteristic index increased progressively with the increase of the proportion of municipal solid waste. And it’s suggested that there was certain interaction in the combustion process of oil shale and municipal solid waste. The average activation energy of the blends reached the minimum value, 177.7927 kJ/mol by Ozawa–Flynn–Wall method and 167.4234 kJ/mol by Friedmen method, when the proportion of MSW was 70%.

Mathematical model for solid fuel combustion in fluidized bed

International Nuclear Information System (INIS)

Kostikj, Zvonimir; Noshpal, Aleksandar

1994-01-01

A mathematical model for computation of the combustion process of solid fuel in fluidized bed is presented in this work. Only the combustor part of the plant (the fluidized bed and the free board) is treated with this model. In that manner, all principal, physical presumption and improvements (upon which this model is based) are given. Finally, the results of the numerical realisation of the mathematical model for combustion of minced straw as well as the results of the experimental investigation of a concrete physical model are presented. (author)

Numerical comparison of hydrogen-air reaction mechanisms for unsteady shockinduced combustion applications

Energy Technology Data Exchange (ETDEWEB)

Kumar, P. Pradeep; Kim, Kui Soon; Oh, Se Jong; Choi, Jeong Yeol [Pusan National University, Busan (Korea, Republic of)

2015-03-15

An unsteady shock-induced combustion (SIC) is characterized by the regularly oscillating combustion phenomenon behind the shock wave supported by the blunt projectile flying around the speed of Chapman-Jouguet detonation wave. The SIC is the coupling phenomenon between the hypersonic flow and the chemical kinetics, but the effects of chemical kinetics have been rarely reported. We compared hydrogen-air reaction mechanisms for the shock-induced combustion to demonstrate the importance of considering the reaction mechanisms for such complex flows. Seven hydrogen-air reaction mechanisms were considered, those available publically and used in other researches. As a first step in the comparison of the hydrogen combustion, ignition delay time of hydrogen-oxygen mixtures was compared at various initial conditions. Laminar premixed flame speed was also compared with available experimental data and at high pressure conditions. In addition, half-reaction length of ZND (Zeldovich-Neumann-Doering) detonation structure accounts for the length scale in SIC phenomena. Oscillation frequency of the SIC is compared by running the time-accurate 3rd-order Navier-Stokes CFD code fully coupled with the detailed chemistry by using four levels of grid resolutions.

Numerical comparison of hydrogen-air reaction mechanisms for unsteady shockinduced combustion applications

International Nuclear Information System (INIS)

Kumar, P. Pradeep; Kim, Kui Soon; Oh, Se Jong; Choi, Jeong Yeol

2015-01-01

An unsteady shock-induced combustion (SIC) is characterized by the regularly oscillating combustion phenomenon behind the shock wave supported by the blunt projectile flying around the speed of Chapman-Jouguet detonation wave. The SIC is the coupling phenomenon between the hypersonic flow and the chemical kinetics, but the effects of chemical kinetics have been rarely reported. We compared hydrogen-air reaction mechanisms for the shock-induced combustion to demonstrate the importance of considering the reaction mechanisms for such complex flows. Seven hydrogen-air reaction mechanisms were considered, those available publically and used in other researches. As a first step in the comparison of the hydrogen combustion, ignition delay time of hydrogen-oxygen mixtures was compared at various initial conditions. Laminar premixed flame speed was also compared with available experimental data and at high pressure conditions. In addition, half-reaction length of ZND (Zeldovich-Neumann-Doering) detonation structure accounts for the length scale in SIC phenomena. Oscillation frequency of the SIC is compared by running the time-accurate 3rd-order Navier-Stokes CFD code fully coupled with the detailed chemistry by using four levels of grid resolutions.

Quantification of fusion in ashes from solid fuel combustion

DEFF Research Database (Denmark)

Hansen, Lone Aslaug; Frandsen, Flemming; Dam-Johansen, Kim

1999-01-01

The fusion of ashes produced during solid fuel combustion greatly affects the tendency of these ashes to cause operational problems in utility boilers. In this paper, a new and quantitative laboratory method for assessing the fusion of ashes based on simultaneous thermal analysis, STA, is described...

Ignition and combustion phenomena on a moving grate: with application to the thermal conversion of biomass and municipal solid waste

NARCIS (Netherlands)

Blijderveen, M.

2012-01-01

Combustion can be defined as a fast oxidation process of a solid, gaseous or liquid fuel at elevated temperatures. In any combustion process, ignition plays an essential role. Not only to initiate the combustion process, but also to maintain it. Especially in solid fuel combustion on a grate, where

Heat Transfer to a Thin Solid Combustible in Flame Spreading at Microgravity

Science.gov (United States)

Bhattacharjee, S.; Altenkirch, R. A.; Olson, S. L.; Sotos, R. G.

1991-01-01

The heat transfer rate to a thin solid combustible from an attached diffusion flame, spreading across the surface of the combustible in a quiescent, microgravity environment, was determined from measurements made in the drop tower facility at NASA-Lewis Research Center. With first-order Arrhenius pyrolysis kinetics, the solid-phase mass and energy equations along with the measured spread rate and surface temperature profiles were used to calculate the net heat flux to the surface. Results of the measurements are compared to the numerical solution of the complete set of coupled differential equations that describes the temperature, species, and velocity fields in the gas and solid phases. The theory and experiment agree on the major qualitative features of the heat transfer. Some fundamental differences are attributed to the neglect of radiation in the theoretical model.

Structures of the particles of the condensed dispersed phase in solid fuel combustion products plasma

International Nuclear Information System (INIS)

Samaryan, A.A.; Chernyshev, A.V.; Nefedov, A.P.; Petrov, O.F.; Fortov, V.E.; Mikhailov, Yu.M.; Mintsev, V.B.

2000-01-01

The results of experimental investigations of a type of dusty plasma which has been least studied--the plasma of solid fuel combustion products--were presented. Experiments to determine the parameters of the plasma of the combustion products of synthetic solid fuels with various compositions together with simultaneous diagnostics of the degree of ordering of the structures of the particles of the dispersed condensed phase were performed. The measurements showed that the charge composition of the plasma of the solid fuels combustion products depends strongly on the easily ionized alkali-metal impurities which are always present in synthetic fuel in one or another amount. An ordered arrangement of the particles of a condensed dispersed phase in structures that form in a boundary region between the high-temperature and condensation zones was observed for samples of aluminum-coated solid fuels with a low content of alkali-metal impurities

Sodium nitrate combustion limit tests

International Nuclear Information System (INIS)

Beitel, G.A.

1976-04-01

Sodium nitrate is a powerful solid oxidant. Energetically, it is capable of exothermically oxidizing almost any organic material. Rate-controlling variables such as temperature, concentration of oxidant, concentration of fuel, thermal conductivity, moisture content, size, and pressure severely limit the possibility of a self-supported exothermic reaction (combustion). The tests reported in this document were conducted on one-gram samples at atmospheric pressure. Below 380 0 C, NaNO 3 was stable and did not support combustion. At moisture concentrations above 22 wt percent, exothermic reactions did not propagate in even the most energetic and reactive compositions. Fresh resin and paraffin were too volatile to enable a NaNO 2 -supported combustion process to propagate. Concentrations of NaNO 3 above 95 wt percent or below 35 wt percent did not react with enough energy release to support combustion. The influence of sample size and confining pressure, both important factors, was not investigated in this study

Study of reaction and heat release from solid combustion in strong magnetic field; Kyojiba wo riyoshita hikinshitsu kotai nensho shori no hanno to netsu no seigy ni kansuru kiso kenkyu

Energy Technology Data Exchange (ETDEWEB)

Ito, K; Fujita, O; Iiya, M; Kudo, K [Hokkaido University, Sapporo (Japan)

1997-02-01

To establish the inhomogeneous solid combustion control technology, effects of the strong magnetic field on the solid combustion were examined. When applying the sufficiently strong magnetic field, it is possible to control the air flow in combustion field by utilizing the force applying to constituent oxygen with large susceptibility. Based on this possibility, combustion experiments of expanded polystyrene plates were conducted between the magnetic poles of electro-magnet having the maximum flux density of 1 T and the maximum magnetic field gradient of 0.5 T/cm. To observe the effects of magnetic field without the effects of natural convection, combustion experiments of acrylic sheets were conducted between the magnetic poles of electro-magnet having the maximum flux density of 0.6 T and the magnetic field gradient of about 0.1 T/cm under the microgravity conditions between 10{sup -4} and 10{sup -5}g using a microgravity test facility. Consequently, prospective combustion results could be obtained, in which the force of flame received from the magnetic field is almost equivalent to the buoyancy of flame. It was demonstrated that combustion can be controlled by the magnetic field. 1 ref., 3 figs., 1 tab.

Numerical Simulation of Solid Combustion with a Robust Conjugate-Gradient Solution for Pressure

National Research Council Canada - National Science Library

Wang, Yi-Zun

2002-01-01

A Bi-Conjugate Gradient method (Bi-CGSTAB) is studied and tested for solid combustion in which the gas and solid phases are coupled by a set of conditions describing mass, momentum and heat transport across the interface...

Cermet materials prepared by combustion synthesis and metal infiltration

Science.gov (United States)

Holt, Joseph B.; Dunmead, Stephen D.; Halverson, Danny C.; Landingham, Richard L.

1991-01-01

Ceramic-metal composites (cermets) are made by a combination of self-propagating high temperature combustion synthesis and molten metal infiltration. Solid-gas, solid-solid and solid-liquid reactions of a powder compact produce a porous ceramic body which is infiltrated by molten metal to produce a composite body of higher density. AlN-Al and many other materials can be produced.

Change in the electric potential of solid fuels on their combustion and gasification

Energy Technology Data Exchange (ETDEWEB)

Fialkov, B.S.; Zakharov, A.G.; Plitsyn, V.T.

1979-01-01

Solid fuels of various degrees of graphitization (graphite, coke, hard coal, lignite) were used to study the changes in electric potential of samples during gasification and combustion in air. The potential shows three peaks during combustion, the third corresponding to ignition. Two peaks occur during the gasification process.

Thermogravimetric analysis of the co-combustion of paper mill sludge and municipal solid waste

International Nuclear Information System (INIS)

Hu, Shanchao; Ma, Xiaoqian; Lin, Yousheng; Yu, Zhaosheng; Fang, Shiwen

2015-01-01

Highlights: • Thermogravimetric analysis of paper mill sludge and municipal solid waste were studied. • The combustion of paper mill sludge could be improved by blending municipal solid waste. • There existed significant interaction during co-combustion of the blends. • The OFW and Starink methods were used to obtain the activation energy. • The average activation energy was the lowest by blending 20% municipal solid waste. - Abstract: The thermal characteristics and kinetics of paper mill sludge (PMS), municipal solid waste (MSW) and their blends in the combustion process were investigated in this study. The mass percentages of PMS in the blends were 10%, 30%, 50%, 70% and 90%, respectively. The experiments were carried out at different heating rates (10 °C/min, 20 °C/min and 30 °C/min) and the temperature ranged from room temperature to 1000 °C in a thermogravimetric simultaneous thermal analyzer. The results suggested that the ignition temperature and burnout temperature of MSW were lower than that of PMS, and the mass loss rate of MSW was larger especially at low temperatures. There were only two mass loss peaks in the differential thermogravimetry (DTG) curve, while three mass loss peaks were observed when the blending ratios of PMS were 30%, 50%, 70%. The value of the comprehensive combustion characteristic index of the blends indicated a good combustibility when the percentage of PMS (PPMS) in the blends was less than 30%. There existed certain interaction between the combustion process of PMS and MSW, especially at high temperature stage. Activation energy (E) value obtained by the Ozawa–Flynn–Wall (OFW) method and the Starink method were very consistent. When the mass percentage of PMS in the blends was 80%, the E average value attained the minimum

Characterisation of metal combustion with DUST code

Energy Technology Data Exchange (ETDEWEB)

García-Cascales, José R., E-mail: jr.garcia@upct.es [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Velasco, F.J.S. [Centro Universitario de la Defensa de San Javier, MDE-UPCT, C/Coronel Lopez Peña s/n, 30730 Murcia (Spain); Otón-Martínez, Ramón A.; Espín-Tolosa, S. [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Bentaib, Ahmed; Meynet, Nicolas; Bleyer, Alexandre [Institut de Radioprotection et Sûreté Nucléaire, BP 17, 92260 Fontenay-aux-Roses (France)

2015-10-15

Highlights: • This paper is part of the work carried out by researchers of the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security of France. • We have developed a code for the study of mobilisation and combustion that we have called DUST by using CAST3M, a multipurpose software for studying many different problems of Mechanical Engineering. • In this paper, we present the model implemented in the code to characterise metal combustion which describes the combustion model, the kinetic reaction rates adopted and includes a first comparison between experimental data and calculated ones. • The results are quite promising although suggest that improvement must be made on the kinetic of the reaction taking place. - Abstract: The code DUST is a CFD code developed by the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security, France (IRSN) with the objective to assess the dust explosion hazard in the vacuum vessel of ITER. Thus, DUST code permits the analysis of dust spatial distribution, remobilisation and entrainment, explosion, and combustion. Some assumptions such as particle incompressibility and negligible effect of pressure on the solid phase make the model quite appealing from the mathematical point of view, as the systems of equations that characterise the behaviour of the solid and gaseous phases are decoupled. The objective of this work is to present the model implemented in the code to characterise metal combustion. In order to evaluate its ability analysing reactive mixtures of multicomponent gases and multicomponent solids, two combustion problems are studied, namely H{sub 2}/N{sub 2}/O{sub 2}/C and H{sub 2}/N{sub 2}/O{sub 2}/W mixtures. The system of equations considered and finite volume approach are briefly presented. The closure relationships used are commented and special attention is paid to the reaction rate correlations used in the model. The numerical

Modelling combustion reactions for gas flaring and its resulting emissions

Directory of Open Access Journals (Sweden)

O. Saheed Ismail

2016-07-01

Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

Simulation of Axial Combustion Instability Development and Suppression in Solid Rocket Motors

OpenAIRE

David R. Greatrix

2009-01-01

In the design of solid-propellant rocket motors, the ability to understand and predict the expected behaviour of a given motor under unsteady conditions is important. Research towards predicting, quantifying, and ultimately suppressing undesirable strong transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. An updated numerical model incorporating recent developments in predi...

Pilot incineration plant for solid, combustible, and low-level wastes

International Nuclear Information System (INIS)

Francioni, W.M.

Radioactively contaminated wastes are formed in the handling of radioactive materials at the Federal Institute for Reactor Research (FIRR) and in other facilities, hospitals, sanitoria, industry, and nuclear power plants. A large part of the wastes are combustible and only very slightly radioactive. Incineration of these wastes is obvious. A pilot incineration plant, henceforth called the PIP, for radioactive combustible wastes of the FIRR is surveyed. The plant and its individual components are described. The production costs of the plant and experience gained in operation available at present are reviewed. Solid combustible radioactive waste can be incinerated in the PIP. The maximum possible reduction in volume of these wastes is achieved by incineration. Subsequently the chemically sterile ashes can be consolidated in a stable block suitable for long-term storage mixing with cement

Assessment of the content of arsenic in solid by-products from coal combustion

Directory of Open Access Journals (Sweden)

Wierońska Faustyna

2017-01-01

Full Text Available The coal combustion processes constitute one of the major sources of heavy metals emission into the atmosphere. From the point of view of the reduction of the emission of heavy metals and the selection of the correct exhaust gas treatment system, it is important to monitor the amount of trace elements in the solid fuels and in the solid by-products from coal combustion. One of these highly toxic elements is arsenic. The average content of arsenic in Polish hard coals and lignites is 0 ÷ 40 mg/kg [1] and 5 ÷ 15 mg/kg [2], respectively. The world average content of arsenic in hard coals and lignites, is equal to 9.0 ± 0.8 and 7.4 ± 1.4 mg/kg [3], respectively. During coal combustion processes, a significant amount of arsenic enters the atmosphere through gases and fly ashes. The proportions in which those two forms of arsenic occur in exhaust gases depend on the conditions of combustion processes [4]. The aim of the research was to determine the content of arsenic in coal blends and by-products of their combustion (slag, fly ash, gypsum, filter cakes. The determination of the arsenic quantity was performed using the Atomic Absorption Spectrometry with the electrothermal atomization.

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

International Nuclear Information System (INIS)

Osborn, David L.

2017-01-01

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

Science.gov (United States)

Osborn, David L.

2017-05-01

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low-temperature combustion and in the oxidation of volatile organic compounds in Earth's atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization makes characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, and master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

Development of a computerized analysis for solid propellant combustion instability with turbulence

Science.gov (United States)

Chung, T. J.; Park, O. Y.

1988-01-01

A multi-dimensional numerical model has been developed for the unsteady state oscillatory combustion of solid propellants subject to acoustic pressure disturbances. Including the gas phase unsteady effects, the assumption of uniform pressure across the flame zone, which has been conventionally used, is relaxed so that a higher frequency response in the long flame of a double-base propellant can be calculated. The formulation is based on a premixed, laminar flame with a one-step overall chemical reaction and the Arrhenius law of decomposition with no condensed phase reaction. In a given geometry, the Galerkin finite element solution shows the strong resonance and damping effect at the lower frequencies, similar to the result of Denison and Baum. Extended studies deal with the higher frequency region where the pressure varies in the flame thickness. The nonlinear system behavior is investigated by carrying out the second order expansion in wave amplitude when the acoustic pressure oscillations are finite in amplitude. Offset in the burning rate shows a negative sign in the whole frequency region considered, and it verifies the experimental results of Price. Finally, the velocity coupling in the two-dimensional model is discussed.

Investigation of the combustion kinetics and polycyclic aromatic hydrocarbon emissions from polycaprolactone combustion.

Science.gov (United States)

Chien, Y C; Yang, S H

2013-01-01

Polycaprolactone (PCL) is one of the most attractive biodegradable plastics that has been widely used in medicine and agriculture fields. Because of the large increase in biodegradable plastics usage, the production of waste biodegradable plastics will be increasing dramatically, producing a growing environmental problem. Generally, waste PCL is collected along with municipal solid wastes and then incinerated. This study investigates the combustion kinetics and emission factors of 16 US Environmental Protection Agency (EPA) priority polycyclic aromatic hydrocarbons (PAHs) in the PCL combustion. Experimentally, two reactions are involved in the PCL combustion process, possibly resulting in the emission of carbon dioxide, propanal, protonated caprolactone and very small amounts of PAH produced by incomplete combustion. The intermediate products may continuously be oxidized to form CO2. The emission factors for 16 US EPA priority PAHs are n.d. -2.95 microg/g, which are much lower than those of poly lactic acid and other plastics combustion. The conversion of PCL is 100%. Results from this work suggest that combustion is a good choice for the waste PCL disposal.

Combustion of large solid fuels in cement rotary kilns

DEFF Research Database (Denmark)

Nielsen, Anders Rooma

(MBM), waste wood, sewage sludge, paper and plastics. The alternative fuel share of the total energy varies significantly from region to region, but the general trend is towards increased alternative fuel utilization. Solid alternative fuels typically have physical and chemical properties that differ...... from traditional solid fossil fuels. This creates a need for new combustion equipment or modification of existing kiln systems, because alternative fuels may influence process stability and product quality. Process stability is mainly influenced by exposing the raw material bed in the rotary kiln...... oxidation is a slow process which may greatly reduce the amounts of solid fuels to be utilized in the material inlet end of rotary kilns due to the limited residence time. Several parameters control the rate of char oxidation: a) bulk oxygen concentration, b) mass transfer rate of oxygen to char particles...

Formation of Liquid Products at the Filtration Combustion of Solid Fuels

Directory of Open Access Journals (Sweden)

E. A. Salgansky

2016-01-01

Full Text Available Yields of liquid and gaseous products of the filtration combustion of cellulose, wood, peat, coal, and rubber have been investigated. Experiments have shown that the gasification of solid fuels in the regime with superadiabatic heating yields liquid hydrocarbons with quantity and quality, which are close to those produced using other methods, for example, by pyrolysis. But in this case no additional energy supply is needed to carry out the gasification process. The low calorific combustible gas, which forms in this process, contains a substantial quantity of carbon monoxide and hydrogen, which are components of syngas.

Combustion of municipal solid wastes with oil shale in a circulating fluidized bed. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-06-30

The problem addressed by our invention is that of municipal solid waste utilization. The dimensions of the problem can be visualized by the common comparison that the average individual in America creates in five years time an amount of solid waste equivalent in weight to the Statue of Liberty. The combustible portion of the more than 11 billion tons of solid waste (including municipal solid waste) produced in the United States each year, if converted into useful energy, could provide 32 quads per year of badly needed domestic energy, or more than one-third of our annual energy consumption. Conversion efficiency and many other factors make such a production level unrealistic, but it is clear that we are dealing with a very significant potential resource. This report describes research pertaining to the co-combustion of oil shale with solid municipal wastes in a circulating fluidized bed. The oil shale adds significant fuel content and also constituents that can possible produce a useful cementitious ash.

Near wall combustion modeling in spark ignition engines. Part B: Post-flame reactions

International Nuclear Information System (INIS)

Demesoukas, Sokratis; Caillol, Christian; Higelin, Pascal; Boiarciuc, Andrei; Floch, Alain

2015-01-01

Highlights: • Models for the post flame reactions (CO and hydrocarbons) and heat release rate are proposed. • ‘Freezing’ effect of CO kinetics is captured but equilibrium CO concentrations are low. • Reactive–diffusive processes are modeled for hydrocarbons and the last stage of combustion is captured. - Abstract: Reduced fuel consumption, low pollutant emissions and adequate output performance are key features in the contemporary design of spark ignition engines. Zero-dimensional numerical simulation is an attractive alternative to engine experiments for the evaluation of various engine configurations. Both flame front reaction and post-flame processes contribute to the heat release rate. The contribution of this work is to highlight and model the role of post-flame reactions (CO and hydrocarbons) in the heat release rate. The modeling approach to CO kinetics used two reactions considered to be dominant and thus more suitable for the description of CO chemical mechanism. Equilibrium concentrations of all the species involved were calculated by a two-zone thermodynamic model. The computed characteristic time of CO kinetics was found to be of a similar order to the results of complex chemistry simulations. The proposed model captured the ‘freezing’ effect (reaction rate is almost zero) for temperatures lower than 1800 K and followed the trends of the measured values at exhaust. However, a consistent underestimation of CO levels at the exhaust was observed. The impact of the remaining CO on the combustion efficiency is considerable especially for rich mixtures. For a remaining 0.4% CO mass fraction, the impact on combustion inefficiency is 0.1%. Unburnt hydrocarbon, which have not reacted within the flame front before quenching, diffuse in the burnt gas and react. In this work, a global reaction rate models the kinetic behavior of hydrocarbon. The diffusion process was modeled by a relaxation equation applied on the calculated kinetic concentration

Research on combustion instability and application to solid propellant rocket motors. II.

Science.gov (United States)

Culick, F. E. C.

1972-01-01

Review of the current state of analyses of combustion instability in solid-propellant rocket motors, citing appropriate measurements and observations. The work discussed has become increasingly important, both for the interpretation of laboratory data and for predicting the transient behavior of disturbances in full-scale motors. Two central questions are considered - namely, linear stability and nonlinear behavior. Several classes of problems are discussed as special cases of a general approach to the analysis of combustion instability. Application to motors, and particularly the limitations presently understood, are stressed.

Effect of fluidization number on the combustion of simulated municipal solid waste in a fluidized bed

International Nuclear Information System (INIS)

Anwar Johari; Mutahharah, M.M.; Abdul, A.; Salema, A.; Kalantarifard, A.; Rozainee, M.

2010-01-01

The effect of fluidization number on the combustion of simulated municipal solid was in a fluidized bed was investigated. Simulated municipal solid waste was used a sample and it was formulated from major waste composition found in Malaysia which comprised of food waste, paper, plastic and vegetable waste. Proximate and ultimate analyses of the simulated were conducted and results showed its composition was similar to the actual Malaysian municipal solid waste composition. Combustion study was carried out in a rectangular fluidized bed with sand of mean particle size of 0.34 mm as a fluidising medium. The range of fluidization numbers investigated was 3 to 11 U mf . The combustion was carried out at stoichiometric condition (Air Factor = 1). Results showed that the best fluidization number was in the range of 5 to 7 U mf with 5 U mf being the most optimum in which the bed temperature was sustained in a much longer period. (author)

Synthesis and characterization of reactions by nanoferrites Co2Fe2O4 combustion

International Nuclear Information System (INIS)

Santos, P.T.A.; Dantas, B.B.; Costa, A.C.F.M.; Araujo, P.M.A.G.

2012-01-01

In this work CoFe 2 O 4 of magnetic nanoparticles were synthesized by combustion reaction and the structural and morphological characteristics of the synthesized samples as well as the parameters of synthesis temperature and reaction time were investigated in order to assess the reproducibility of the synthesis. The maximum temperature and time of the combustion flame were obtained with pyrometer coupled to a computer with online measurement and a stopwatch. The resulting samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The maximum temperature achieved during synthesis for all reactions ranged from 623 deg C and 755 deg C. The combustion flame time varied between 18 and 23 seconds. The XRD showed the formation of only CoFe 2 O 4 inverse spinel phase, with crystallite size 28 nm and crystallinity 78%, with typical morphology of the formation of agglomerates of uniform size, brittle and comprising nanoparticles together by weak forces. (author)

The Pictet-Spengler reaction in solid-phase combinatorial chemistry

DEFF Research Database (Denmark)

Nielsen, Thomas E; Diness, Frederik; Meldal, Morten

2003-01-01

The Pictet-Spengler reaction is an important reaction for the generation of tetrahydro-beta-carbolines and tetrahydroisoquinoline ring systems, which exhibit a range of biological and pharmacological properties. This review covers the solid-phase Pictet-Spengler reaction, as employed in solid...

Measurement of characteristics of solid flow in the cyclone separators with fiber optical probe

International Nuclear Information System (INIS)

Li Shaohua; Li Yan; Li Jinjing; Yang Shi; Yang Hairui; Zhang Hai; Lu Junfu; Yue Guangxi

2009-01-01

In some applications, e.g. circulating fluidized beds (CFB), cyclones are usually operated at high solid loadings. Under high inlet solid concentration, most of the particles are collected at the wall and form a dense particle spiral band because of high separation efficiency. As a result, gas-solid reactions should occur mostly in the near-wall region. To understand the gas-solid reaction mechanism in the cyclone, an experimental study was conducted in a plexiglass CFB cold apparatus, with a riser of 0.2m I.D. and 5m high, and a standard Lapple cyclone. Fiber optical probe was used to measure the characteristics of solid flow in the cyclone, including particle velocity and volumetric solid concentration, especially in the near-wall region of the cyclone. Based on the experiment results, the combustion of carbon particles in the cyclone of a CFB boiler was estimated with group combustion theory. The calculated results show that combustion effectiveness factor ηeff of near-wall particle cloud is smaller than 1/25, which means the combustion rate of a carbon particle in the near-wall region is greatly restricted by other particles in the cloud.

Chlorine in solid fuels fired in pulverized fuel boilers sources, forms, reactions, and consequences: a literature review

Energy Technology Data Exchange (ETDEWEB)

David A. Tillman; Dao Duong; Bruce Miller [Foster Wheeler North America Corp. (United States)

2009-07-15

Chlorine is a significant source of corrosion and deposition, both from coal and from biomass, and in PF boilers. This investigation was designed to highlight the potential for corrosion risks associated with once-through units and advanced cycles. The research took the form of a detailed literature investigation to evaluate chlorine in solid fuels: coals of various ranks and origins, biomass fuels of a variety of types, petroleum cokes, and blends of the above. The investigation focused upon an extensive literature review of documents dating back to 1991. The focus is strictly corrosion and deposition. To address the deposition and corrosion issues, this review evaluates the following considerations: concentrations of chlorine in available solid fuels including various coals and biomass fuels, forms of chlorine in those fuels, and reactions - including reactivities - of chlorine in such fuels. The assessment includes consideration of alkali metals and alkali earth elements as they react with, and to, the chlorine and other elements (e.g., sulfur) in the fuel and in the gaseous products of combustion. The assessment also includes other factors of combustion: for example, combustion conditions including excess O{sub 2} and combustion temperatures. It also considers analyses conducted at all levels: theoretical calculations, bench scale laboratory data and experiments, pilot plant experiments, and full scale plant experience. Case studies and plant surveys form a significant consideration in this review. The result of this investigation focuses upon the concentrations of chlorine acceptable in coals burned exclusively, in coals burned with biomass, and in biomass cofired with coal. Values are posited based upon type of fuel and combustion technology. Values are also posited based upon both first principles and field experience. 86 refs., 8 figs., 7 tabs.

Characterizations of self-combustion reactions (SCR) for the production of nanomaterials used as advanced cathodes in Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Haik, Ortal; Martha, Surendra K.; Sclar, Hadar; Samuk-Fromovich, Zvi; Zinigrad, Ella; Markovsky, Boris [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); Kovacheva, Daniela; Saliyski, Nikolay [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria); Aurbach, Doron, E-mail: aurbach@mail.biu.ac.il [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel)

2009-09-10

In this work, self-combustion reactions (SCR) for the preparation of important cathode materials for rechargeable Li-ion batteries were investigated by thermal analytical tools (DSC, ARC, TGA), electron microscopy, XRD, various spectroscopies (MS, Raman, FTIR) and elemental analysis by ICP. The systems studied include solutions containing metal nitrates at the right stoichiometry and sucrose as a fuel, for the preparation of LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} (layered), LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} (spinel), LiMn{sub 0.33}Ni{sub 0.33}Co{sub 0.33}O{sub 2} (layered), and LiMn{sub 0.4}Ni{sub 0.4}Co{sub 0.2}O{sub 2} (layered). Similar products, which do not depend on the atmosphere of the processes (air or inert) were obtained by spontaneous SCR and the gradual heating of the same solutions by DSC, ARC, and TGA. The reactions involve the partial caramelization of sucrose, complicated by red-ox reactions with the nitrates that form solid products, whose organic part is finally decomposed around 400 {sup o}C. The presence of cobalt ions has a stabilizing effect, which is expressed by the low dissolution rates of Li ions from the solid products thus formed, into aqueous solutions. The reaction mechanisms are discussed herein.

Analysis of the fuel influence in obtaining HAp by combustion reaction

International Nuclear Information System (INIS)

Santos, T.L.; Leite, A.M.D.; Viana, K.M.S.

2016-01-01

The search for new materials for biomedical applications has led to investigation of the calcium phosphate bioceramics, and in particular hydroxyapatite (HAp), being a material similar to bone tissue, with excellent biocompatibility and high osteoconduction, enabling bone regeneration which allows the use at implants and prostheses. The synthesis of the nanometric HAp by combustion reaction enables obtaining the nanometric HAp with a more similar structure biological apatite as possible. This work aims to synthesize HAp by combustion reaction using two different routes of synthesis, first, using urea as fuel and the second using glycine, after this, evaluate the influence of fuels used in the microstructure of the hydroxyapatite obtained. The HAp obtained was characterized by: XRD, FTIR and SEM. Through analysis of the results, there is the synthesis conditions used that glycine has performed more favorable to obtaining HAp. (author)

Multifunctional (NOx/CO/O2) Solid-State Sensors For Coal Combustion Control

Energy Technology Data Exchange (ETDEWEB)

Eric D. Wachsman

2006-12-31

Solid-state sensors were developed for coal combustion control and the understanding of sensing mechanisms was advanced. Several semiconducting metal oxides (p-type and n-type) were used to fabricate sensor electrodes. The adsorption/desorption characteristics and catalytic activities of these materials were measured with Temperature Programmed Desorption (TPD) and Temperature Programmed Reaction (TPR) experiments. The sensitivity, selectivity, and response time of these sensors were measured for steps of NO, NO{sub 2}, CO, CO{sub 2}, O{sub 2}, and H{sub 2}O vapor in simple N{sub 2}-balanced and multi-component, simulated combustion-exhaust streams. The role of electrode microstructure and fabrication parameters on sensing performance was investigated. Proof for the proposed sensing mechanism, Differential Electrode Equilibria, was demonstrated by relating the sensing behavior (sensitivities and cross-sensitivities) of the various electrode materials to their gas adsorption/desorption behaviors and catalytic activities. A multifunctional sensor array consisting of three sensing electrodes and an integrated heater and temperature sensors was fabricated with tape-casting and screen-printing and its NO{sub x} sensing performance was measured. The multifunctional sensor demonstrated it was possible to measure NO{sub 2} independent of NO by locally heating one of the sensing electrodes. The sensor technology was licensed to Fuel FX International, Inc. Fuel FX has obtained investor funding and is developing prototype sensors as a first step in their commercialization strategy for this technology.

Modelling of a combustion process for the incineration of municipal solid waste

International Nuclear Information System (INIS)

Rohyiza Ba'an Sivapalan Kathiravale Mohamad Puad Abu Muhd Noor Muhd Yunus

2005-01-01

Municipal Solid Waste (MSW) in Malaysia is increasing rapidly with increase in the population and economic growth. Landfill capacity required to accommodate the generated waste is anticipated to exceed 20,000 tons per day by year 2020. The current management system of solely depending on landfill disposal is inadequate and calls for a more environmentally friendly management system, which include the prospects of an eco park. To understand the combustion process, the development of mathematical model based on waste characteristic is required. Hence this paper will present the mathematical model developed to predict the mass and heat balance for MSW combustion process. This results of this mathematical model will be compared against the actual combustion of MSW in Thermal Oxidation Plant, so that the accuracy of the developed model can be determined accordingly. (Author)

Regenerable mixed copper-iron-inert support oxygen carriers for solid fuel chemical looping combustion process

Energy Technology Data Exchange (ETDEWEB)

Siriwardane, Ranjani V.; Tian, Hanjing

2016-12-20

The disclosure provides an oxygen carrier for a chemical looping cycle, such as the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The oxygen carrier is comprised of at least 24 weight % (wt %) CuO, at least 10 wt % Fe2O3, and an inert support, and is typically a calcine. The oxygen carrier exhibits a CuO crystalline structure and an absence of iron oxide crystalline structures under XRD crystallography, and provides an improved and sustained combustion reactivity in the temperature range of 600.degree. C.-1000.degree. C. particularly for solid fuels such as carbon and coal.

for the inference of Furan combustion reaction rate

KAUST Repository

Long, Quan

2016-01-06

We carry out the design of experiments for the identification of the reaction parameters in Furan combustion. The lacks of information on the true value of the control parameters, specifically, the initial temperature and the initial TBHP concentration, are considered in the design procedure by errors-invariables models. We use two types of observables. The first is a scaler observable, i.e., half decay time of the [TBHP]. The second is the time history of the concentration.

Synthesis by the Pechini method and reaction combustion for the preparation of TiO2: a comparative analysis

International Nuclear Information System (INIS)

Almeida, E.P.; Ribeiro, P.C.; Freitas, N.L.; Lira, H.L.; Costa, A.C.F.M. da; Kiminami, R.H.G.A.

2009-01-01

The aim of this work is to prepare TiO 2 powder by Pechini and combustion reaction methods. A comparative analysis between the structural and morphological results obtained by the two methods was investigated. The powders were characterized by X-ray diffractions (XRD), infrared analysis, nitrogen adsorption (BET) and particle size distribution. The results from XRD show that the powders prepared by Pechini method and by combustion reaction using aniline as fuel, present anatase as major phase and traces of rutile phase. The values of crystallite size and surface area from BET were: 30 e 44 nm; 6.2 e 4.4 m 2 /g, for the powders prepared by Pechini and combustion reaction, respectively. The values of particle size were: 21.9 e 5.3 μm, for the powders prepared by Pechini and combustion reaction, respectively. The Pechini method was more suitable to obtain powders with irregular agglomerates, in the block shape with particles bonded softly and small crystallite size. (author)

A shock tube study of the reactions of the hydroxyl radical with combustion species

Energy Technology Data Exchange (ETDEWEB)

Cohen, N.; Koffend, J.B. [The Aerospace Corporation, Los Angeles, CA (United States)

1993-12-01

To extend the semi-empirical techniques of Benson and coworkers, and to extend the database of reliable high temperature measurements of OH radicals with hydrocarbons and other fuels and their decomposition products, the authors undertook a research program with both experimental and computational tasks. The experimental goal was to design a procedure for measuring, at combustion temperatures, the reaction rate coefficients of OH radicals with fuels and other species of importance in combustion or propulsion systems. The computational effort was intended to refine the semi-empirical transition-state-theory procedures for extrapolating rate coefficients of reactions of OH with combustion species of interest, for predicting rate coefficients for species not studied in the laboratory, and to examine the ability of the theory to predict rate coefficients for different pathways in the case the reagent possessed more than one nonequivalent H atoms.

Transport processes in exothermic gas-solid reactions

International Nuclear Information System (INIS)

Vijay, P.L.; Sathiyamoorthy, D.

1997-01-01

The variation of the concentration of gaseous reactant, temperature distribution for an exothermic reaction, the diffusivity factor and the reaction ratio profiles with various radial positions of a solid reactant have been computed and illustrated for a specific case of reduction reaction of UO 3 by hydrogen

Combustion synthesis of advanced materials. [using in-situ infiltration technique

Science.gov (United States)

Moore, J. J.; Feng, H. J.; Perkins, N.; Readey, D. W.

1992-01-01

The combustion synthesis of ceramic-metal composites using an in-situ liquid infiltration technique is described. The effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e. solids, liquids and gases, with varying physical properties e.g. thermal conductivity, on the microstructure and morphology of synthesized products is also described. Alternatively, conducting the combustion synthesis reaction in a reactive gas environment is also discussed, in which advantages can be gained from the synergistic effects of combustion synthesis and vapor phase transport. In each case, the effect of the presence or absence of gravity (density) driven fluid flow and vapor transport is discussed as is the potential for producing new and perhaps unique materials by conducting these SHS reactions under microgravity conditions.

Investigations of combustion process in combined cooker-boiler fired on solid fuels

Directory of Open Access Journals (Sweden)

Stojiljković Dragoslava D.

2006-01-01

Full Text Available The aim of the investigation was to make some reconstructions on the existing stove used for cooking and baking and to obtain the combined cooker-boiler which will fulfill the demands of European standard EN 12815. Implementation of modern scientific achievements in the field of combustion on stoves and furnaces fired on solid fuels was used. During the investigations four various constructions were made with different fresh air inlet and secondary air supply with the intention to obtain more complete combustion with increased efficiency and reduced CO emission. Three different fuels were used: firewood, coal, and wood briquette. A numerous parameters were measured: fuel weight changes during the combustion process, temperature of inlet and outlet water, flue gas composition (O2, CO, SO2, CO2, NOx, flue gas temperature, ash quantity etc. The result of the investigations is the stove with the efficiency of more than 75% - boiler Class 1 (according EN 12815 and CO emission of about 1% v/v. The results obtained during the measurements were used as parameters for modeling of combustion process. .

Nanocrystalline spinel ferrites by solid state reaction route

Indian Academy of Sciences (India)

Wintec

Nanocrystalline spinel ferrites by solid state reaction route. T K KUNDU* and S MISHRA. Department of Physics, Visva-Bharati, Santiniketan 731 235, India. Abstract. Nanostructured NiFe2O4, MnFe2O4 and (NiZn)Fe2O4 were synthesized by aliovalent ion doping using conventional solid-state reaction route. With the ...

Unified approach to the study of solid fuel combustion characteristics at high airflow speeds

Science.gov (United States)

Vnuchkov, D. A.; Lukashevich, S. V.; Nalivaychenko, D. G.; Zvegintsev, V. I.

2017-10-01

The main objective of the research is the development of guidelines for a unified approach to testing the combustion of different solid fuels in gaseous oxidant high-speed flow, so that research outcomes could be presented in a standardized and cohesive form. All the experiments were performed on a special experimental installation designed for quantification of the burning characteristics of different fuels in a wide range of the airflow parameters at the same geometry of the combustion chamber.

Thermogravimetric investigation on the degradation properties and combustion performance of bio-oils.

Science.gov (United States)

Ren, Xueyong; Meng, Jiajia; Moore, Andrew M; Chang, Jianmin; Gou, Jinsheng; Park, Sunkyu

2014-01-01

The degradation properties and combustion performance of raw bio-oil, aged bio-oil, and bio-oil from torrefied wood were investigated through thermogravimetric analysis. A three-stage process was observed for the degradation of bio-oils, including devolatilization of the aqueous fraction and light compounds, transition of the heavy faction to solid, and combustion of carbonaceous residues. Pyrolysis kinetics parameters were calculated via the reaction order model and 3D-diffusion model, and combustion indexes were used to qualitatively evaluate the thermal profiles of tested bio-oils for comparison with commercial oils such as fuel oils. It was found that aged bio-oil was more thermally instable and produced more combustion-detrimental carbonaceous solid. Raw bio-oil and bio-oil from torrefied wood had comparable combustion performance to fuel oils. It was considered that bio-oil has a potential to be mixed with or totally replace the fuel oils in boilers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

KAUST Repository

Shi, Xian

2017-01-05

Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

KAUST Repository

Shi, Xian; Ryu, Je Ir; Chen, Jyh-Yuan; Dibble, Robert W.

2017-01-01

Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

Method for the combustion of a gas, in fixed bed, with an oxidized solid and associated installation

OpenAIRE

Abanades García, Juan Carlos; Fernández García, José Ramón

2014-01-01

[EN] The present invention pertains to the field of the generation of energy from combustible gases, incorporating the capture of carbon dioxide for use or permanent storage and, specifically relates to cyclical methods of gas combustion with oxidized solids (chemical looping processes), in fixed bed, for solving the problem of controlling temperature in the combustion of gaseous fuels in fixed beds of metal oxides operating at high pressures, and also the associated installation.

Morphology, composition, and mixing state of primary particles from combustion sources ? crop residue, wood, and solid waste

OpenAIRE

Liu, Lei; Kong, Shaofei; Zhang, Yinxiao; Wang, Yuanyuan; Xu, Liang; Yan, Qin; Lingaswamy, A. P.; Shi, Zongbo; Lv, Senlin; Niu, Hongya; Shao, Longyi; Hu, Min; Zhang, Daizhou; Chen, Jianmin; Zhang, Xiaoye

2017-01-01

Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combusti...

Experimental Studies on Combustion Characteristics of Mixed Municipal Solid Waste

Institute of Scientific and Technical Information of China (English)

Fan Jiang; Zhonggang Pan; Shi Liu; Haigang Wang

2003-01-01

In our country, municipal solid wastes (MSW) are always burnt in their original forms and only a few pretreatments are taken. Therefore it is vital to study the combustion characteristics of mixed waste. In this paper,thermogravimetric analysis and a lab scale fluidized bed facility were used as experimental means. The data in two different experimental systems were introduced and compared. It took MSW 3～3.5 rain to burn out in FB, but in thermogravimetric analyzer, the time is 20～25 min. It can be concluded that, in general, the behavior of a mixture of waste in TGA can be expressed by simple combination of individual components of the waste mixtures.Only minor deviations from the rule were observed. Yet, in Fluidized Bed, it was found that, for some mixtures,there was interference among the components during fluidized bed combustion.

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

OpenAIRE

David Greatrix

2015-01-01

The ability to predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms typically necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. On the mitigation side, one in practice sees the use of inert or reactive particles for the suppression of pressure wave ...

Oxy-fuel combustion of solid fuels

DEFF Research Database (Denmark)

Toftegaard, Maja Bøg; Brix, Jacob; Jensen, Peter Arendt

2010-01-01

Oxy-fuel combustion is suggested as one of the possible, promising technologies for capturing CO2 from power plants. The concept of oxy-fuel combustion is removal of nitrogen from the oxidizer to carry out the combustion process in oxygen and, in most concepts, recycled flue gas to lower the flame...... provide additional options for improvement of process economics are however likewise investigated. Of particular interest is the change of the combustion process induced by the exchange of carbon dioxide and water vapor for nitrogen as diluent. This paper reviews the published knowledge on the oxy......-fuel process and focuses particularly on the combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics. Knowledge is currently available regarding both an entire oxy-fuel power plant and the combustion fundamentals. However, several...

A DMS kinetic study of the boron oxides vapor in the combustion front of SHS system Mo + B

International Nuclear Information System (INIS)

Kashireninov, O.E.; Yuranov, I.A.

1994-01-01

The distribution of the boron oxides vapor in the combustion wave of the SHS system Mo + B has been studied by the dynamic mass spectrometry technique (DMS) to test the thermodynamically based hypothesis for the key role of gas-phase transport in solid-state combustion. The molecular beam sampling of the gases over the burning tablet was performed by a stationary probe cone from the moving combustion wave. Ion currents of boron oxides were recorded at 10--20 ms intervals that afforded spatial resolution of 0.1--0.2 mm. It has been found that the distribution of the boron oxides vapor pressure along the combustion wave corresponds to the known zones of preheating, reaction, and postcombustion. The rapid increase of B 2 O 2 pressure takes place in the preheating zone as a result of the reaction B(s) + B 2 O 3 (g) = B 2 O 2 (g). Boron oxides are not observed over the reaction zone because of their complete decay in the reaction with Mo(s) to form molybdenum boride(s). The appearance The appearance of boron oxide vapors over the postcombustion zone is due to the evaporation of B 2 O 3 (l). The effective kinetic parameters are estimated from the data obtained. The results show that solid-state combustion of the Mo + B system proceeds predominantly through formation of gas-phase boron oxides

Chemical reaction on solid surface observed through isotope tracer technique

International Nuclear Information System (INIS)

Tanaka, Ken-ichi

1983-01-01

In order to know the role of atoms and ions on solid surfaces as the partners participating in elementary processes, the literatures related to the isomerization and hydrogen exchanging reaction of olefines, the hydrogenation of olefines, the metathesis reaction and homologation of olefines based on solid catalysts were reviewed. Various olefines, of which the hydrogen atoms were substituted with deuterium at desired positions, were reacted using various solid catalysts such as ZnO, K 2 CO 3 on C, MoS 2 (single crystal and powder) and molybdenum oxide (with various carriers), and the infra-red spectra of adsorbed olefines on catalysts, the isotope composition of reaction products and the production rate of the reaction products were measured. From the results, the bonding mode of reactant with the atoms and ions on solid surfaces, and the mechanism of the elementary process were considered. The author emphasized that the mechanism of the chemical reaction on solid surfaces and the role of active points or catalysts can be made clear to the considerable extent by combining isotopes suitably. (Yoshitake, I.)

Synthesis of nano-sized hydroxyapatite powders through solution combustion route under different reaction conditions

International Nuclear Information System (INIS)

Ghosh, Samir Kumar; Roy, Sujit Kumar; Kundu, Biswanath; Datta, Someswar; Basu, Debabrata

2011-01-01

Calcium hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 (HAp) was synthesized by combustion in the aqueous system containing calcium nitrate-diammonium hydrogen orthophosphate with urea and glycine as fuels. These ceramics are important materials for biomedical applications. Thermo-gravimetric and differential thermal analysis were employed to understand the nature of synthesis process during combustion. Effects of different process parameters namely, nature of fuel (urea and glycine), fuel to oxidizer ratio (0.6-4.0) and initial furnace temperature (300-700 o C) on the combustion behavior as well as physical properties of as-formed powders were investigated. A series of combustion reactions were carried out to optimize the reaction parameters for synthesis of nano-sized HAp powders. The combustion temperature (T f ) for the oxidant and fuels were calculated to be 896 deg. C and 1035 deg. C for the stoichiometric system of urea and glycine respectively. The stoichiometric glycine-calcium nitrate produced higher flame temperature (both calculated and measured) and powder with lower specific surface area (8.75 m 2 /g) compared to the stoichiometric urea-calcium nitrate system (10.50 m 2 /g). Fuel excess combustion in both glycine and urea produced powders with higher surface area. Nanocrystalline HAp powder could be synthesized in situ with a large span of fuel to oxidizer ratio (φ) in case of urea system (0.8 < φ < 4) and (0.6 < φ < 1.5) for the glycine system. Calcium hydroxyapatite particles having diameters ranging between 20 nm and 120 nm could be successfully synthesized through optimized process variable.

Diffusion Driven Combustion Waves in Porous Media

Science.gov (United States)

Aldushin, A. P.; Matkowsky, B. J.

2000-01-01

Filtration of gas containing oxidizer, to the reaction zone in a porous medium, due, e.g., to a buoyancy force or to an external pressure gradient, leads to the propagation of Filtration combustion (FC) waves. The exothermic reaction occurs between the fuel component of the solid matrix and the oxidizer. In this paper, we analyze the ability of a reaction wave to propagate in a porous medium without the aid of filtration. We find that one possible mechanism of propagation is that the wave is driven by diffusion of oxidizer from the environment. The solution of the combustion problem describing diffusion driven waves is similar to the solution of the Stefan problem describing the propagation of phase transition waves, in that the temperature on the interface between the burned and unburned regions is constant, the combustion wave is described by a similarity solution which is a function of the similarity variable x/square root of(t) and the wave velocity decays as 1/square root of(t). The difference between the two problems is that in the combustion problem the temperature is not prescribed, but rather, is determined as part of the solution. We will show that the length of samples in which such self-sustained combustion waves can occur, must exceed a critical value which strongly depends on the combustion temperature T(sub b). Smaller values of T(sub b) require longer sample lengths for diffusion driven combustion waves to exist. Because of their relatively small velocity, diffusion driven waves are considered to be relevant for the case of low heat losses, which occur for large diameter samples or in microgravity conditions, Another possible mechanism of porous medium combustion describes waves which propagate by consuming the oxidizer initially stored in the pores of the sample. This occurs for abnormally high pressure and gas density. In this case, uniformly propagating planar waves, which are kinetically controlled, can propagate, Diffusion of oxidizer decreases

Simulation of Axial Combustion Instability Development and Suppression in Solid Rocket Motors

Directory of Open Access Journals (Sweden)

David R. Greatrix

2009-03-01

Full Text Available In the design of solid-propellant rocket motors, the ability to understand and predict the expected behaviour of a given motor under unsteady conditions is important. Research towards predicting, quantifying, and ultimately suppressing undesirable strong transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. An updated numerical model incorporating recent developments in predicting negative and positive erosive burning, and transient, frequency-dependent combustion response, in conjunction with pressure-dependent and acceleration-dependent burning, is applied to the investigation of instability-related behaviour in a small cylindrical-grain motor. Pertinent key factors, like the initial pressure disturbance magnitude and the propellant's net surface heat release, are evaluated with respect to their influence on the production of instability symptoms. Two traditional suppression techniques, axial transitions in grain geometry and inert particle loading, are in turn evaluated with respect to suppressing these axial instability symptoms.

A Model for Nitrogen Chemistry in Oxy-Fuel Combustion of Pulverized Coal

DEFF Research Database (Denmark)

Hashemi, Hamid; Hansen, Stine; Toftegaard, Maja Bøg

2011-01-01

, heating and devolatilization of particles, and gas–solid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal combustion in O2/CO2 and air, covering the effects of fuel, mixing conditions, temperature......In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows......, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-fuel combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N2 with CO2. According to the model, differences in the NO yield between the oxy...

The reduction of air pollution by improved combustion

Energy Technology Data Exchange (ETDEWEB)

Churchill, S.W. [Pennsylvania Univ., Chemical Engineering Dept., Philadelphia, PA (United States)

1997-12-31

The contributions of combustion to air pollution and possible remedies are discussed. Control and reduction of air pollution from combustion is more feasible than from other sources because of its discrete localization. The gaseous products of combustion inevitably include H{sub 2}O and CO{sub 2}, NO and/or NO{sub 2} and may include N{sub 2}O, SO{sub 2}, SO{sub 3} and unburned and partially burned hydrocarbons. Soot, ash and other dispersed solids may also be present, but are not considered herein. Unburned and partially burned hydrocarbons are prima facie evidence of poor mechanics of combustion and should not be tolerated. On the other hand, NO{sub x}, SO{sub 2} and SO{sub 3} are unavoidable if the fuel contains nitrogen and sulfur. The best remedy in this latter case is to remove these species from the fuel. Otherwise their products of combustion must be removed by absorption, adsorption or reaction. NO{sub x} from the fixation of N{sub 2} in the air and CO may be minimized by advanced techniques of combustion. One such method is described in some detail. If CO{sub 2} must be removed this can be accomplished by absorption, adsorption or reaction, but precooling is necessary and the quantity is an order of magnitude greater than that of any of the other pollutants. (Author)

Combustible and incombustible speciation of Cl and S in various components of municipal solid waste.

Science.gov (United States)

Watanabe, Nobuhisa; Yamamoto, Osamu; Sakai, Mamoru; Fukuyama, Johji

2004-01-01

Chlorine (Cl) and sulfur (S) in municipal solid waste (MSW) are important reactive elements during combustion. They generate the acidic pollutants HCl and SOx, and, furthermore, produce and suppress organic chlorinated compounds. Nevertheless, few practical reports about Cl and S content in MSW have been published. In combustion and recycling processes, both combustible Cl and S, and incombustible Cl and S species are equally important. This paper presents the results of a comprehensive study about combustible and incombustible Cl and S in MSW components, including kitchen garbage, paper, textiles, wood and leaves, plastics and small chips. By integrating this collected data with data about MSW composition, not only the overall content of Cl and S in MSW, but also the origins of both combustible and incombustible Cl and S were estimated. The average Cl content in bulk MSW was 3.7 g/kg of raw MSW, of which 2.7 and 1.0 g/kg were combustible and incombustible, respectively. The Cl contribution from plastics was 76% and 27% with respect to combustible and incombustible states. The average S content in bulk MSW was 0.81 g/kg of raw MSW, of which 0.46 g/kg was combustible and 0.35 g/kg was incombustible. Combustible S was mainly due to synthetic textiles, while incombustible S was primarily from paper.

Combustion of Solid Propellants (La Combustion des Propergols Solides)

Science.gov (United States)

1991-07-01

the of ether and ethyl alcohol and removing objective of these lectures to give a this solvent. Instead of having a fibrous comprehensive understanding...do cetto esrne do Les propergols composites, A matrice confifrences une description tout A fait A polymarique charg~o pst, un oxydant at un jour des...rusa., De nouveaux souvant suppos6 qua la vitesa des gaz de oxydes de for ultrafirts mont aujourd’hui combustion est n~gligeable at qua d~velopps pour

Nanocrystalline (U0.5Ce0.5)O2±x solid solutions through citrate gel-combustion

Science.gov (United States)

Maji, D.; Ananthasivan, K.; Venkata Krishnan, R.; Balakrishnan, S.; Amirthapandian, S.; Joseph, Kitheri; Dasgupta, Arup

2018-04-01

Nanocrystalline powders of (U0.5Ce0.5)O2±x solid solutions were synthesized in bulk (100-200 g) through the citrate gel combustion. The fuel (citric acid) to oxidant (nitrate) mole ratio (R) was varied from 0.1 to 1.0. Two independent lots of the products obtained through the gel-combustion were calcined at 973 K in air and in a mixture of argon containing 8% H2 respectively. All these powders were characterized for their bulk density, X-ray crystallite size, specific surface area, size distribution of the particles, porosity as well as residual carbon. The morphology and microstructures of these powders were studied by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Nanocrystalline single phase fluorite solid solutions having a typical crystallite size of about (7-15 nm) were obtained. These powders were highly porous comprising cuboidal flaky agglomerates. The combustion mixture with an 'R' value of 0.25 was found to undergo volume combustion and was found to yield a product that was distinctly different. The systematic investigation on synthesis and characterization of nanocrystalline UCeO2 is reported for the first time.

Determination of sulfur in solids by constant current coulometric titration following combustion

International Nuclear Information System (INIS)

Monteiro, R.P.G.

1986-01-01

A method for determination of sulfur in solid materials by combustion in induction furnace, followed by constant current coulometric titration of the sulfur dioxide produced, is described. The method is applicable to samples with sulfur contents of 80 ppm to 20,000 ppm. Its feasibility was checked on the NBS and Leco steel samples. The results are in good agreement with the specified values. (author) [pt

Ignition delays, heats of combustion, and reaction rates of aluminum alkyl derivatives used as ignition and combustion enhancers for supersonic combustion

Science.gov (United States)

Ryan, Thomas W., III; Schwab, S. T.; Harlowe, W. W.

1992-01-01

The subject of this paper is the design of supersonic combustors which will be required in order to achieve the needed reaction rates in a reasonable sized combustor. A fuel additive approach, which is the focus of this research, is the use of pyrophorics to shorten the ignition delay time and to increase the energy density of the fuel. Pyrophoric organometallic compounds may also provide an ignition source and flame stabilization mechanism within the combustor, thus permitting use of hydrocarbon fuels in supersonic combustion systems. Triethylaluminum (TEA) and trimethylaluminum (TMA) were suggested for this application due to their high energy density and reactivity. The objective here is to provide comparative data for the ignition quality, the energy content, and the reaction rates of several different adducts of both TEA and TMA. The results of the experiments indicate the aluminum alkyls and their more stable derivatives reduce the ignition delay and total reaction time to JP-10 jet fuel. Furthermore, the temperature dependence of ignition delay and total reaction time of the blends of the adducts are significantly lower than in neat JP-10.

Contribution to the modelling of gas-solid reactions and reactors; Contribution a la modelisation des reactions et des reacteurs gaz-solide

Energy Technology Data Exchange (ETDEWEB)

Patisson, F

2005-09-15

Gas-solid reactions control a great number of major industrial processes involving matter transformation. This dissertation aims at showing that mathematical modelling is a useful tool for both understanding phenomena and optimising processes. First, the physical processes associated with a gas-solid reaction are presented in detail for a single particle, together with the corresponding available kinetic grain models. A second part is devoted to the modelling of multiparticle reactors. Different approaches, notably for coupling grain models and reactor models, are illustrated through various case studies: coal pyrolysis in a rotary kiln, production of uranium tetrafluoride in a moving bed furnace, on-grate incineration of municipal solid wastes, thermogravimetric apparatus, nuclear fuel making, steel-making electric arc furnace. (author)

On the combustion mechanisms of ZrH2 in double-base propellant.

Science.gov (United States)

Yang, Yanjing; Zhao, Fengqi; Yuan, Zhifeng; Wang, Ying; An, Ting; Chen, Xueli; Xuan, Chunlei; Zhang, Jiankan

2017-12-13

Metal hydrides are regarded as a series of promising hydrogen-supplying fuel for solid rocket propellants. Their effects on the energetic and combustion performances of propellants are closely related to their reaction mechanisms. Here we report a first attempt to determine the reaction mechanism of ZrH 2 , a high-density metal hydride, in the combustion of a double-base propellant to evaluate its potential as a fuel. ZrH 2 is determined to possess good resistance to oxidation by nitrocellulose and nitroglycerine. Thus its combustion starts with dehydrogenation to generate H 2 and metallic Zr. Subsequently, the newly formed Zr and H 2 participate in the combustion and, especially, Zr melts and then combusts on the burning surface which favors the heat feedback to the propellant. This phenomenon is completely different from the combustion behavior of the traditional fuel Al, where the Al particles are ejected off the burning surface of the propellant to get into the luminous flame zone to burn. The findings in this work validate the potential of ZrH 2 as a hydrogen-supplying fuel for double-base propellants.

Effect of radiative transfer of heat released from combustion reaction on temperature distribution: A numerical study for a 2-D system

International Nuclear Information System (INIS)

Zhou Huaichun; Ai Yuhua

2006-01-01

Both light and heat are produced during a chemical reaction in a combustion process, but traditionally all the energy released is taken as to be transformed into the internal energy of the combustion medium. So the temperature of the medium increases, and then the thermal radiation emitted from it increases too. Chemiluminescence is generated during a chemical reaction and independent of the temperature, and has been used widely for combustion diagnostics. It was assumed in this paper that the total energy released in a combustion reaction is divided into two parts, one part is a self-absorbed heat, and the other is a directly emitted heat. The former is absorbed immediately by the products, becomes the internal energy and then increases the temperature of the products as treated in the traditional way. The latter is emitted directly as radiation into the combustion domain and should be included in the radiation transfer equation (RTE) as a part of radiation source. For a simple, 2-D, gray, emitting-absorbing, rectangular system, the numerical study showed that the temperatures in reaction zones depended on the fraction of the directly emitted energy, and the smaller the gas absorption coefficient was, the more strong the dependence appeared. Because the effect of the fraction of the directly emitted heat on the temperature distribution in the reacting zones for gas combustion is significant, it is required to conduct experimental measurements to determine the fraction of self-absorbed heat for different combustion processes

Reflight of the Solid Surface Combustion Experiment: Opposed-Flow Flame Spread Over Cylindrical Fuels

Science.gov (United States)

Bhattacharjee, Subrata; Altenkirch, Robert A.; Worley, Regis; Tang, Lin; Bundy, Matt; Sacksteder, Kurt; Delichatsios, Michael A.

1997-01-01

The effort described here is a reflight of the Solid Surface Combustion Experiment (SSCE), with extension of the flight matrix first and then experiment modification. The objectives of the reflight are to extend the understanding of the interplay of the radiative processes that affect the flame spread mechanisms.

Plasma assisted combustion of parafin mixture

International Nuclear Information System (INIS)

Nedybaliuk, O.A.; Chernyak, V.Ya.; Martysh, E.V.; Lisitchenko, T.E.; Vergun, O.Yu.; Orlovska, S.G.

2013-01-01

In this work the results of solid paraffin combustion with the aid of the plasma of transverse and rotational gliding arc studies are represented. The question of the additional activation of paraffin based solid fuels is examined. The mixture of n-paraffin and stearin in the solid state as the model of the solid paraffin based fuel is used. The plasma assisted combustion of this model is experimentally investigated. The voltage-current characteristics of discharge at the different regimes are measured. The population temperatures of excited rotational levels are determined. The flame temperature during the combustion of solid paraffin containing mixture is calculated

Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method

International Nuclear Information System (INIS)

Takatori, Kazumasa; Tani, Takao; Watanabe, Naoyoshi; Kamiya, Nobuo

1999-01-01

The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia-ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia-ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources

Improvement in devices for carbonization at low temperature of solid combustibles

Energy Technology Data Exchange (ETDEWEB)

1947-07-07

A complete device is described for the carbonization at low temperature of solid combustibles, characterized by the fact that the pyrogenation furnace proper is constructed in such a way as to permit pyrolysis by external heating in a thin layer with an ultra rapid evacuation of the gases and of the vapors of pyrolysis at the moment of their formation, and comprising means of mechaniccal agitation to promote the transmission of heat from the heating gases and the material to be pyrolized.

Sample preparation techniques based on combustion reactions in closed vessels - A brief overview and recent applications

International Nuclear Information System (INIS)

Flores, Erico M.M.; Barin, Juliano S.; Mesko, Marcia F.; Knapp, Guenter

2007-01-01

In this review, a general discussion of sample preparation techniques based on combustion reactions in closed vessels is presented. Applications for several kinds of samples are described, taking into account the literature data reported in the last 25 years. The operational conditions as well as the main characteristics and drawbacks are discussed for bomb combustion, oxygen flask and microwave-induced combustion (MIC) techniques. Recent applications of MIC techniques are discussed with special concern for samples not well digested by conventional microwave-assisted wet digestion as, for example, coal and also for subsequent determination of halogens

The effects of changing municipal solid waste characteristics on combustion fuel quality

International Nuclear Information System (INIS)

Artz, N.S.; Franklin, M.A.

1991-01-01

This paper discusses the quality of municipal solid waste (MSW) as a combustion fuel based on two aspects: heat of combustion and heavy metal content. Characterization of MSW by the material flows methodology now provides a historical data series on the composition of MSW for nearly 30 years (1960-1988). Over this period, there have been marked changes in MSW composition, with paper and plastics increasing in percentage while glass and metals have declined. This paper will illustrate the effects of this changing composition on heat of combustion. Using a computer model and standard heat of combustion values for the components of MSW, heating values of MSW (in Btu per pound) are calculated for the 30-year time period. Changes in heating values are highlighted and projections are made to year 2010. Recognizing the increasing importance of the recovery of materials from MSW for recycling, the paper illustrates the effects of removing varying quantities of recyclable materials (e.g., newspapers, corrugated boxes, plastic bottles, glass bottles, metals, yard wastes) on the heating value of the remaining MSW. The paper's final section summarizes recent studies performed for EPA and others on the presence of heavy metals (lead, cadmium, and mercury) in the products discarded in MSW. Again, time trends are used to demonstrate the changing presence of these metals

A study of paint sludge deactivation by pyrolysis reactions

Directory of Open Access Journals (Sweden)

Muniz L.A.R.

2003-01-01

Full Text Available The production of large quantities of paint sludge is a serious environmental problem. This work evaluates the use of pyrolysis reaction as a process for deactivating paint sludge that generates a combustible gas phase, a solvent liquid phase and an inert solid phase. These wastes were classified into three types: water-based solvent (latex resin and solvents based on their resins (alkyd and polyurethane. An electrically heated stainless steel batch reactor with a capacity of 579 mL and a maximum pressure of 30 atm was used. Following the reactor, a flash separator, which was operated at atmospheric pressure, partially condensed and separated liquid and gas products. Pressure and temperature were monitored on-line by a control and data acquisition system, which adjusted the heating power supplied to the pyrolysis reactor. Reactions followed an experimental design with two factors (reaction time and temperature and three levels (10, 50 and 90 minutes; 450, 550 and 650degreesC. The response variables were liquid and solid masses and net heat of combustion. The optimal operational range for the pyrolysis process was obtained for each response variable. A significant reduction in total mass of solid waste was obtained.

Ignition delays, heats of combustion, and reaction rates of aluminum alkyl derivatives used as ignition and combustion enhancers for supersonic combustors

Science.gov (United States)

Ryan, T. W., III; Harlowe, W. W.; Schwab, S.

1992-01-01

The work was based on adapting an apparatus and procedure developed at Southwest Research Institute for rating the ignition quality of fuels for diesel engines. Aluminum alkyls and various Lewis-base adducts of these materials, both neat and mixed 50/50 with pure JP-10 hydrocarbon, were injected into the combustion bomb using a high-pressure injection system. The bomb was pre-charged with air that was set at various initial temperatures and pressures for constant oxygen density. The ignition delay times were determined for the test materials at these different initial conditions. The data are presented in absolute terms as well as comparisons with the parent alkyls. The relative heats of reaction of the various test materials were estimated based on a computation of the heat release, using the pressure data recorded during combustion in the bomb. In addition, the global reaction rates for each material were compared at a selected tmperature and pressure.

Biomass pyrolysis and combustion integral and differential reaction heats with temperatures using thermogravimetric analysis/differential scanning calorimetry.

Science.gov (United States)

Shen, Jiacheng; Igathinathane, C; Yu, Manlu; Pothula, Anand Kumar

2015-06-01

Integral reaction heats of switchgrass, big bluestem, and corn stalks were determined using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). Iso-conversion differential reaction heats using TGA/DSC pyrolysis and combustion of biomass were not available, despite reports available on heats required and released. A concept of iso-conversion differential reaction heats was used to determine the differential reaction heats of each thermal characteristics segment of these materials. Results showed that the integral reaction heats were endothermic from 30 to 700°C for pyrolysis of switchgrass and big bluestem, but they were exothermic for corn stalks prior to 587°C. However, the integral reaction heats for combustion of the materials followed an endothermic to exothermic transition. The differential reaction heats of switchgrass pyrolysis were predominantly endothermic in the fraction of mass loss (0.0536-0.975), and were exothermic for corn stalks (0.0885-0.850) and big bluestem (0.736-0.919). Study results provided better insight into biomass thermal mechanism. Published by Elsevier Ltd.

Reaction Mechanisms and HCCI Combustion Processes of Mixtures of n-Heptane and the Butanols

Directory of Open Access Journals (Sweden)

Hu eWang

2015-03-01

Full Text Available A reduced primary reference fuel (PRF-Alcohol-Di-tert-butyl Peroxide (DTBP mechanism with 108 species and 435 reactions, including sub-mechanisms of PRF, methanol, ethanol, DTBP and the four butanol isomers, is proposed for homogeneous charge compression ignition (HCCI engine combustion simulations of butanol isomers/n-heptane mixtures. HCCI experiments fuelled with butanol isomer/n-heptane mixtures on two different engines are conducted for the validation of proposed mechanism. The mechanism has been validated against shock tube ignition delays, laminar flame speeds, species profiles in premixed flames and engine HCCI combustion data, and good agreements with experimental results are demonstrated under various validation conditions. It is found that although the reactivity of neat tert-butanol is the lowest, mixtures of tert-butanol/n-heptane exhibit the highest reactivity among the butanol isomer/n-heptane mixtures if the n-heptane blending ratio exceeds 20% (mole. Kinetic analysis shows that the highest C-H bond energy in the tert-butanol molecule is partially responsible for this phenomenon. It is also found that the reaction tC4H9OH+CH3O2 =tC4H9O+CH3O2H plays important role and eventually produces the OH radical to promote the ignition and combustion. The proposed mechanism is able to capture HCCI combustion processes of the butanol/n-heptane mixtures under different operating conditions. In addition, the trend that tert-butanol /n-heptane has the highest reactivity is also captured in HCCI combustion simulations. The results indicate that the current mechanism can be used for HCCI engine predictions of PRF and alcohol fuels.

Non-radioactive verification test of ZRF25 radioactive combustible solid waste incinerator

International Nuclear Information System (INIS)

Wang Peiyi; Li Xiaohai; Yang Liguo

2013-01-01

This paper mainly introduces the construction and test run of ZRF25 radioactive combustible solid waste incinerator, by a series of simulating waste tests, such as 24 h test, 72 h test, 168 h test, making a conclusion that the incinerator runs reliably. In addition, all of the indexes (such as treatment capacity, volume reduction coefficient, clinker ignition loss of incineration ash) meet the requirements of contract and pollution discharging standards. (authors)

Morphology, composition, and mixing state of primary particles from combustion sources - crop residue, wood, and solid waste.

Science.gov (United States)

Liu, Lei; Kong, Shaofei; Zhang, Yinxiao; Wang, Yuanyuan; Xu, Liang; Yan, Qin; Lingaswamy, A P; Shi, Zongbo; Lv, Senlin; Niu, Hongya; Shao, Longyi; Hu, Min; Zhang, Daizhou; Chen, Jianmin; Zhang, Xiaoye; Li, Weijun

2017-07-11

Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combustion released OM and S-rich particles. Interestingly, particles from hardwood (pear wood and bamboo) and softwood (cypress and pine wood) combustion were mainly soot and OM in the flaming phase, respectively. The combustion of foam boxes, rubber tires, and plastic bottles/bags in the flaming phase released large amounts of soot internally mixed with a small amount of OM, whereas the combustion of printed circuit boards and copper-core cables emitted large amounts of OM with Br-rich inclusions. In addition, the printed circuit board combustion released toxic metals containing Pb, Zn, Sn, and Sb. The results are important to document properties of primary particles from combustion sources, which can be used to trace the sources of ambient particles and to know their potential impacts in human health and radiative forcing in the air.

Trace elements in co-combustion of solid recovered fuel and coal

DEFF Research Database (Denmark)

Wu, Hao; Glarborg, Peter; Jappe Frandsen, Flemming

2013-01-01

Trace element partitioning in co-combustion of a bituminous coal and a solid recovered fuel (SRF) was studied in an entrained flow reactor. The experiments were carried out at conditions similar to pulverized coal combustion, with SRF shares of 7.9 wt.% (wet basis), 14.8 wt.% and 25.0 wt.......%. In addition, the effect of additives such as NaCl, PVC, ammonium sulphate, and kaolinite on trace element partitioning was investigated. The trace elements studied were As, Cd, Cr, Pb, Sb and Zn, since these elements were significantly enriched in SRF as compared to coal. During the experiments, bottom ash...... was collected in a chamber, large fly ash particles were collected by a cyclone with a cut-off diameter of ~2.5 μm, and the remaining fly ash particles were gathered in a filter. It was found that when coal was co-fired with SRF, the As, Cd, Pb, Sb and Zn content in filter ash/cyclone ash increased almost...

Combustion

CERN Document Server

Glassman, Irvin

1987-01-01

Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

Decoupled numerical simulation of a solid fuel fired retort boiler

International Nuclear Information System (INIS)

Ryfa, Arkadiusz; Buczynski, Rafal; Chabinski, Michal; Szlek, Andrzej; Bialecki, Ryszard A.

2014-01-01

The paper deals with numerical simulation of the retort boiler fired with solid fuel. Such constructions are very popular for heating systems and their development is mostly based on the designer experience. The simulations have been done in ANSYS/Fluent package and involved two numerical models. The former deals with a fixed-bed combustion of the solid fuel and free-board gas combustion. Solid fuel combustion is based on the coal kinetic parameters. This model encompasses chemical reactions, radiative heat transfer and turbulence. Coal properties have been defined with user defined functions. The latter model describes flow of water inside a water jacked that surrounds the combustion chamber and flue gas ducts. The novelty of the proposed approach is separating of the combustion simulation from the water flow. Such approach allows for reducing the number of degrees of freedom and thus lowering the necessary numerical effort. Decoupling combustion from water flow requires defining interface boundary condition. As this boundary condition is unknown it is adjusted iteratively. The results of the numerical simulation have been successfully validated against measurement data. - Highlights: • New decoupled modelling of small scale boiler is proposed. • Fixed-bed combustion model based on kinetic parameters is introduced. • Decoupling reduced the complexity of the model and computational time. • Simple and computationally inexpensive coupling algorithm is proposed. • Model is successfully validated against measurements

Kinetic concepts of thermally stimulated reactions in solids

Science.gov (United States)

Vyazovkin, Sergey

Historical analysis suggests that the basic kinetic concepts of reactions in solids were inherited from homogeneous kinetics. These concepts rest upon the assumption of a single-step reaction that disagrees with the multiple-step nature of solid-state processes. The inadequate concepts inspire such unjustified anticipations of kinetic analysis as evaluating constant activation energy and/or deriving a single-step reaction mechanism for the overall process. A more adequate concept is that of the effective activation energy, which may vary with temperature and extent of conversion. The adequacy of this concept is illustrated by literature data as well as by experimental data on the thermal dehydration of calcium oxalate monohydrate and thermal decomposition of calcium carbonate, ammonium nitrate and 1,3,5,7- tetranitro-1,3,5,7-tetrazocine.

Energy and emission aspects of co-combustion solid recovered fuel with coal in a stoker boiler

Science.gov (United States)

Wasielewski, Ryszard; Głód, Krzysztof; Telenga-Kopyczyńska, Jolanta

2018-01-01

The results of industrial research on co-combustion of solid recovered fuel (SRF) with hard coal in a stoker boiler type WR-25 has been presented. The share of SRF in the fuel mixture was 10%. During the co-combustion of SRF, no technological disturbances or significant reduction in energy efficiency of the boiler were noted. Obtained SO2, NOx and CO emissions were comparable with coal combustion but dust emissions increased. During combustion of the coal mixture with a 10% share of SRF in the test boiler WR-25, the emission standards established for the combustion of the dedicated fuel were met. However, comparison of obtained emission results with the emission standards established for co-incineration of waste, revealed the exceedance of permissible levels of HCl, dust, heavy metals, dioxins and furans. Additionally, the residence time of flue gases in over 850°C conditions for the test boiler WR-25 was too short (1.3 seconds) in refer to the legislative requirements (2 seconds) for the thermal conversion of waste.

Energy and emission aspects of co-combustion solid recovered fuel with coal in a stoker boiler

Directory of Open Access Journals (Sweden)

Wasielewski Ryszard

2018-01-01

Full Text Available The results of industrial research on co-combustion of solid recovered fuel (SRF with hard coal in a stoker boiler type WR-25 has been presented. The share of SRF in the fuel mixture was 10%. During the co-combustion of SRF, no technological disturbances or significant reduction in energy efficiency of the boiler were noted. Obtained SO2, NOx and CO emissions were comparable with coal combustion but dust emissions increased. During combustion of the coal mixture with a 10% share of SRF in the test boiler WR-25, the emission standards established for the combustion of the dedicated fuel were met. However, comparison of obtained emission results with the emission standards established for co-incineration of waste, revealed the exceedance of permissible levels of HCl, dust, heavy metals, dioxins and furans. Additionally, the residence time of flue gases in over 850°C conditions for the test boiler WR-25 was too short (1.3 seconds in refer to the legislative requirements (2 seconds for the thermal conversion of waste.

Combustion physics

Science.gov (United States)

Jones, A. R.

1985-11-01

Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

Combustion of Solid Fuel in a Vortex Furnace with Counter-swirling Flows

Directory of Open Access Journals (Sweden)

Redko A.A.

2017-12-01

Full Text Available The results of computer simulation of the processes of incineration of low-grade solid fuel-pulverized peat with a moisture content of 40%, an ash content of 6% are given. It has been determined the fields of distribution of temperature, velocity of gases and particles in the volume and at the outlet from the furnace. The three-dimensional temperature distribution in the combustion chamber indicates high-temperature combustion of peat particles at temperatures above 1700°C with liquid ash removal in the lower part of the furnace. It has been determined that when the furnace is cooled, it is not ensured combustion of the fuel completely. The value of the swirling flow rate at the outlet from the furnace (up to 370 m/s ensures the efficiency of separation of fuel particles, reducing heat losses from mechanical underburning. It is determined that the concentration of oxygen is close to zero over the entire height of the furnace, at an outlet from the furnace the oxygen concentration is 5...6%, since oxygen is supplied with excess (αв=1,2. The results of a numerical study showed that the diameter of peat particles affects the process of their combustion: coke particles with an initial diameter of 25 mkm to 250 mkm burn out by 96%. With an increase in particle diameter up to 1000 mkm, the degree of burn-out of coke decreases, but at the same time their removal decreases. It is shown that the furnace ensures the completeness of combustion of peat particles of peat 99.8%, volatiles is 100%.

Solid waste combustion for alpha waste incineration

International Nuclear Information System (INIS)

Orloff, D.I.

1981-02-01

Radioactive waste incinerator development at the Savannah River Laboratory has been augmented by fundamental combustion studies at the University of South Carolina. The objective was to measure and model pyrolysis and combustion rates of typical Savannah River Plant waste materials as a function of incinerator operating conditions. The analytical models developed in this work have been incorporated into a waste burning transient code. The code predicts maximum air requirement and heat energy release as a function of waste type, package size, combustion chamber size, and temperature. Historically, relationships have been determined by direct experiments that did not allow an engineering basis for predicting combustion rates in untested incinerators. The computed combustion rates and burning times agree with measured values in the Savannah River Laboratory pilot (1 lb/hr) and full-scale (12 lb/hr) alpha incinerators for a wide variety of typical waste materials

The effect of interfaces on solid-state reactions between oxides

International Nuclear Information System (INIS)

Johnson, M.T.; Carter, C.B.

1998-01-01

A thin-film geometry has been used to study fundamental solid-state reaction processes occurring at interfaces in two spinel-forming oxide systems. In the first system, NiO/Al 2 O 3 , epitactic NiO films were deposited on various orientations of single-crystal α-Al 2 O 3 . In this case, the reaction kinetics were studied and correlated with the interfacial structure (or substrate orientation). In the second, In 2 O 3 /MgO, solid-state reactions were studied under the influence of an electric field. The electric field provides a driving force for mass transport that affects both the reaction process and the morphological stability of an interface

Developments in, and environmental impacts of, electricity generation from municipal solid waste and landfill gas combustion

International Nuclear Information System (INIS)

Porteous, A.

1993-01-01

The 1991 NFFO allocations for renewable energy generation are reviewed with emphasis on electricity from municipal solid waste (MSW) and landfill gas (LFG) combustion tranches. The implications of materials recovery on the calorific value of MSW are considered, as are the environmental impacts of both MSW and LFG combustion with special reference to air pollutant emissions. The performance and economics of state of the art incineration and LFG power generating plants are examined. It is shown that energy recovery from these wastes can be both cost effective and environmentally desirable. (Author)

Incineration facility for combustible solid and liquid radioactive wastes in IPEN-CNEN - Sao Paulo

International Nuclear Information System (INIS)

Krutman, I.; Grosche Filho, C.E.; Chandra, U.; Suarez, A.A.

1987-01-01

A system for incinerating the combustible solid and liquid radioactive wastes was developed in order to achieve higher mass and volume reduction of the wastes generated at IPEN-CNEN/SP or received from other institutions. The radioactive wastes for incineration are: animal carcasses, ion-exchange resins, contaminated lubricant oils, cellulosic materials, plastics, etc. The optimization of the process was achieved by considering the following factors: selection of better construction and insulating material; dimensions; modular design of combustion chambers to increase burning capacity in future; applicability for various types of wastes; choise of gas cleaning system. The off-gas system utilizes dry treatment. The operation is designed to function with a negative pressure. (Author) [pt

Experimental study on the mechanism of SO2 emission and calcium-based desulfurization in the coal oxygen-enriched combustion

International Nuclear Information System (INIS)

Tian, Luning; Chen, Hanping; Yang, Haiping; Wang, Xianhua; Zhang, Shihong

2010-01-01

Full text: The emission of SO 2 , CO 2 brings serious harm to the ecological environment, human health and the global climate change. The largest source of SO 2 , CO 2 is the combustion of fossil fuels for power generation. So developing the new technology for controlling pollutants emissions from coal combustion was imperative. Oxygen-enriched combustion technology is such a new technology which can realize CO 2 zero emission, enhance the combustion efficiency and reduce pollutants emission. Due to the high concentration of CO 2 , it has many different aspects in the SO 2 emission and calcium-based desulfurization compare with the conventional combustion. In this article, experiments have been done to investigate the behavior and mechanism of SO 2 emissions and removal in oxygen-enriched combustion. First, in TGA and fixed bed reactor, the SO 2 emission characteristics were investigated under various bed temperature, particle size and O 2 / CO 2 concentration. It was observed that SO 2 released faster and the emission peak was higher than air atmosphere. SO 2 emission concentration increased with the reaction temperature increasing. Simultaneously, the mechanism of SO 2 emission was obtained by analyzing the sulfur compounds in the gas products and solid products in different reaction times. Then, the impacts of reaction temperature, particle size, O 2 / CO 2 concentration and SO 2 concentration etc. on the efficiency of SO 2 removal were analyzed. The phase analysis, pore diameter distribution and microstructure of the solid product were investigated. The experimental results showed that the sulphur capture takes place by direct sulphation reaction at high CO 2 concentration which attributes to light sinter, better porous structure, higher optimal desulfurization temperature and high desulfurization efficiency of calcium-based sorbent. (author)

Chemical degradation of proteins in the solid state with a focus on photochemical reactions.

Science.gov (United States)

Mozziconacci, Olivier; Schöneich, Christian

2015-10-01

Protein pharmaceuticals comprise an increasing fraction of marketed products but the limited solution stability of proteins requires considerable research effort to prepare stable formulations. An alternative is solid formulation, as proteins in the solid state are thermodynamically less susceptible to degradation. Nevertheless, within the time of storage a large panel of kinetically controlled degradation reactions can occur such as, e.g., hydrolysis reactions, the formation of diketopiperazine, condensation and aggregation reactions. These mechanisms of degradation in protein solids are relatively well covered by the literature. Considerably less is known about oxidative and photochemical reactions of solid proteins. This review will provide an overview over photolytic and non-photolytic degradation reactions, and specially emphasize mechanistic details on how solid structure may affect the interaction of protein solids with light. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical Looping Combustion Reactions and Systems

Energy Technology Data Exchange (ETDEWEB)

Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

2014-03-01

, they performed a sensitivity analysis for velocity, height and polydispersity and compared results against literature data for experimental studies of CLC beds with no reaction. Finally, they present an optimization space using simple non-reactive configurations. In Subtask 5.3, through a series of experimental studies, behavior of a variety of oxygen carriers with different loadings and manufacturing techniques was evaluated under both oxidizing and reducing conditions. The influences of temperature, degree of carrier conversion and thermodynamic driving force resulting from the difference between equilibrium and system O{sub 2} partial pressures were evaluated through several experimental campaigns, and generalized models accounting for these influences were developed to describe oxidation and oxygen release. Conversion of three solid fuels with widely ranging reactivities was studied in a small fluidized bed system, and all but the least reactive fuel (petcoke) were rapidly converted by oxygen liberated from the CLOU carrier. Attrition propensity of a variety of carriers was also studied, and the carriers produced by freeze granulation or impregnation of preformed substrates displayed the lowest rates of attrition. Subtask 5.4 focused on gathering kinetic data for a copper-based oxygen carrier to assist with modeling of a functioning chemical looping reactor. The kinetics team was also responsible for the development and analysis of supported copper oxygen carrier material.

Production methods for decreasing nitrous oxide effluents during solid fuel combustion

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.

1981-01-01

The atmosphere can be protected from toxic NO /SUB x/ effluents during fuel combustion in boilers by reducing the amount of NO /SUB x/ during combustion or by cleaning the smoky gases after they leave the boiler. The second method results from the need to process a large amount of smoky gases with a relatively low concentration of nitrous oxide which is chemically resistant and which is not highly soluble in water. The problem is complicated by the SO /SUB x/ , O/sub 2/ and solid particles in the smoky gaes. The method for cleaning smoky gases is complicated and requires mator capital investments and operating expenses. Laboratory tests in the F. E. Dzerzhinskiy Heat Engineering Institute showed that thermal NO /SUB x/ is formed at combustion temperatures above 1550/sup 0/C, and that the concentration of O/sub 2/ has a significant impact on NO /SUB x/ formation, while temperature has much less effect. On the basis of laboratory and industrial tests, the Institute recommended a method to reduce NO /SUB x/ effluents from large boilers: for Kansk-Achinski coals -- low-temperature combustion. The temperature in the combustion nucleus is maintained at 1290/sup 0/C by using a set of measures individual dust systems with direct intection, grinder-blowers, fuel drying and recirculation of about 20% of the smoky gases with the primary air, tangential direct flow burners in several rows along the top). The effectiveness of this system has been checked on a PK-10Sh boiler at the Krasnoyarsk Thermal Power Plant No. 1 and a BK3-210-140 boiler at the Vladivostok Thermal Power Plant No. 2. Further reduction of NO /SUB x/ (by about 20%) requires redistribution of the secondary air along the row of burners. These measures are suggested for use on the P-67 boiler of the 800 MW unit of the Berezovsk State Regional Power Station No. 1. A brief summary of the design and operating measures are provided.

Radiation energy devaluation in diffusion combusting flows of natural gas

International Nuclear Information System (INIS)

Makhanlall, Deodat; Munda, Josiah L.; Jiang, Peixue

2013-01-01

Abstract: CFD (Computational fluid dynamics) is used to evaluate the thermodynamic second-law effects of thermal radiation in turbulent diffusion natural gas flames. Radiative heat transfer processes in gas and at solid walls are identified as important causes of energy devaluation in the combusting flows. The thermodynamic role of thermal radiation cannot be neglected when compared to that of heat conduction and convection, mass diffusion, chemical reactions, and viscous dissipation. An energy devaluation number is also defined, with which the optimum fuel–air equivalence for combusting flows can be determined. The optimum fuel–air equivalence ratio for a natural gas flame is determined to be 0.7. The CFD model is validated against experimental measurements. - Highlights: • Thermodynamic effects of thermal radiation in combusting flows analyzed. • General equation for second-law analyses of combusting flows extended. • Optimum fuel–air equivalence ratio determined for natural gas flame

Experimental COPD induced by solid combustible burn smoke in rats: a study of the emphysematous changes of the pulmonary parenchyma.

Science.gov (United States)

Murărescu, Elena Doina; Eloae-Zugun, Fl; Mihailovici, Maria Sultana

2008-01-01

According to the GOLD 2006 definition, COPD is a preventable and treatable pathological situation characterized by the partially reversible airflow limitation determined by a variable proportion mixture of small airways disease (obliterative bronchiolitis) and parenchyma destruction (emphysema). A major impediment in the study of the COPD is represented by the fact the fundamental morphological changes that determine the major pulmonary dysfunction take place in the small, peripheral, airways, at the bronchiolo-alveolar attachments. That is why the experimental model of COPD developed progressively to the transgenic mouse. There are many experimental studies on the animal models that have obtained emphysema rapidly through intratraheal instillation of elastasis or bronchitis/bronchiolitis through intratraheal instillation of particles. It is accepted that the unnatural character of aggression, that does not permit the natural evolution of the inflammatory phenomenon, limits these models and tissue remodeling that take place in COPD patients. It is well known that cigarette smoking is a major cause of COPD. There have been reported some cases of COPD in never smoking patients exposed to air pollutants. We aimed to create an experimental model of COPD in rat through exposure to smoke resulted from solid combustibles burn for the same period and in the same conditions of cigarette smoke exposure and to compare the pulmonary morphological changes. Thirty Wistar rats were divided into three groups (n = 10): (1) the control group (C), (2) the cigarette smoke group (CS), and (3) the solid combustible smoke group (SCS). Apart from the control group, these were treated with solid combustibles smoke (SCS group) or cigarette smoke (CS group) for six months. Morphological and morphometry studies have been assessed. We have established a rat COPD model based on natural cigarette smoke exposure versus solid combustible burn resulted smoke, usable for a further approach in human

Influence of Mn and Co on structural and morphological characteristics of ZnO synthesized by combustion reaction

International Nuclear Information System (INIS)

Torquato, R.A.; Costa, C.F.M.; Kiminami, R.H.A.

2010-01-01

This study aims to evaluate the effect of doping of 0.2 mol of Mn and Co on structural and morphological characteristics of ZnO synthesized by combustion reaction. During the synthesis was the measurement of temperature and time of the combustion flame. The samples were characterized by XRD, SEM, particle size distribution and nitrogen adsorption (BET). The maximum temperature the reactions were 428 deg C and 436 deg C, reaction time, and 115 and 0 seconds for the samples doped with Mn and Co, respectively. The XRD data showed that for both impurities were formed only ZnO phase. For Co were formed secondary phase CoO. The crystallite size and surface area were 18 nm and 22 nm, and 52 and 38 m2/g for ZnO doped with Mn and Co, respectively. (author)

Fifteenth combustion research conference

International Nuclear Information System (INIS)

1993-01-01

The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers

Combustion synthesis by reaction and characterization of structural Ni-Zn ferrite doped with copper

International Nuclear Information System (INIS)

Dantas, J.; Santos, J.R.D.; Cunha, R.B.L.; Feitosa, C.A.; Costa, A.C.F.M.

2012-01-01

The present stud aims to evaluate the effect of doping with Cu 2+ ions concentrations of 0.0, 0.1, 0.2, 0.3 and 0.4 mol in the synthesis and structure of Ni-Zn ferrite. Samples were synthesized by the method of the combustion reaction and characterized by measuring the temperature as a function of reaction time, X-ray diffraction (XRD) and infrared spectroscopy in Fourier transform (FTIR). The combustion temperature and time were 646, 900, 989, 975 and 735°C and 210, 175, 220, 210 and 110 seconds for the sample doped with 0.0, 0.1, 0.2, 0.3 and 0.4 mol of copper, respectively. XRD results show that all concentrations of copper evaluated, there was only a training phase inverse spinel ferrite and Ni-Zn FTIR spectra show absorption bands below 1000cm -1 , which are characteristics of the spinel type AB 2 O 4- (author)

Reactions of solid CaSO{sub 4} and Na{sub 2}CO{sub 3} and formation of sodium carbonate sulfate double salts

Energy Technology Data Exchange (ETDEWEB)

Wang, Jinsheng; Wu, Yinghai; Anthony, Edward J. [CANMET Energy Technology Centre, Natural Resources Canada, 1 Haanel Dr., Ottawa, Ontario K1A 1M1 (Canada)

2007-07-01

High-temperature chemical reactions in mixtures of solid CaSO{sub 4} and Na{sub 2}CO{sub 3} were investigated in order to explore the mechanisms of enhanced sulfur capture by limestones doped with Na{sub 2}CO{sub 3} in fluidized bed combustion. Drastic weight loss of the mixtures was observed in a thermogravimetric analyzer near the melting temperature of Na{sub 2}CO{sub 3}, indicating chemical reaction. X-ray diffraction analysis for a mixture of the solids following a heat treatment at 850 C revealed the existence of two sodium carbonate sulfate double salts that have not been reported before for the present system. The formation of Na{sub 2}SO{sub 4} in the melt of Na{sub 2}CO{sub 3} appears to precede the formation of the double salts. The two double salts are believed to have high porosity and specific surface area similar to those of a better-known double salt, burkeite. The implications of these findings for the enhancement of limestone sulfation by Na{sub 2}CO{sub 3} are also discussed. (author)

Reactions of solid CaSO{sub 4} and Na{sub 2}CO{sub 3} and formation of sodium carbonate sulfate double salts

Energy Technology Data Exchange (ETDEWEB)

Wang Jinsheng [CANMET Energy Technology Centre, Natural Resources Canada, 1 Haanel Dr., Ottawa, Ontario K1A 1M1 (Canada)]. E-mail: jiwang@nrcan.gc.ca; Wu Yinghai [CANMET Energy Technology Centre, Natural Resources Canada, 1 Haanel Dr., Ottawa, Ontario K1A 1M1 (Canada); Anthony, Edward J. [CANMET Energy Technology Centre, Natural Resources Canada, 1 Haanel Dr., Ottawa, Ontario K1A 1M1 (Canada)

2007-07-01

High-temperature chemical reactions in mixtures of solid CaSO{sub 4} and Na{sub 2}CO{sub 3} were investigated in order to explore the mechanisms of enhanced sulfur capture by limestones doped with Na{sub 2}CO{sub 3} in fluidized bed combustion. Drastic weight loss of the mixtures was observed in a thermogravimetric analyzer near the melting temperature of Na{sub 2}CO{sub 3}, indicating chemical reaction. X-ray diffraction analysis for a mixture of the solids following a heat treatment at 850 deg. C revealed the existence of two sodium carbonate sulfate double salts that have not been reported before for the present system. The formation of Na{sub 2}SO{sub 4} in the melt of Na{sub 2}CO{sub 3} appears to precede the formation of the double salts. The two double salts are believed to have high porosity and specific surface area similar to those of a better-known double salt, burkeite. The implications of these findings for the enhancement of limestone sulfation by Na{sub 2}CO{sub 3} are also discussed.

Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler

Directory of Open Access Journals (Sweden)

Jun-Xia Zhang

2016-03-01

Full Text Available Because the air-staged combustion technology is one of the key technologies with low investment running costs and high emission reduction efficiency for the pulverized boiler, it is important to reveal the chemical reaction kinetics mechanism for developing various technologies of nitrogen oxide reduction emissions. At the present work, a three-dimensional mesh model of the large-scale four corner tangentially fired boiler furnace is established with the GAMBIT pre-processing of the FLUENT software. The partial turbulent premixed and diffusion flame was simulated for the air-staged combustion processing. Parameters distributions for the air-staged and no the air-staged were obtained, including in-furnace flow field, temperature field and nitrogen oxide concentration field. The results show that the air-staged has more regular velocity field, higher velocity of flue gas, higher turbulence intensity and more uniform temperature of flue gas. In addition, a lower negative pressure zone and lower O2 concentration zone is formed in the main combustion zone, which is conducive to the NO of fuel type reduced to N2, enhanced the effect of NOx reduction. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th November 2015; Revised: 14th January 2016; Accepted: 16th January 2016  How to Cite: Zhang, J.X., Zhang, J.F. (2016. Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 100-108. (doi:10.9767/bcrec.11.1.431.100-108 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.431.100-108

Burning Questions in Gravity-Dependent Combustion Science

Science.gov (United States)

Urban, David; Chiaramonte, Francis P.

2012-01-01

Building upon a long history of spaceflight and ground based research, NASA's Combustion Science program has accumulated a significant body of accomplishments on the ISS. Historically, NASAs low-gravity combustion research program has sought: to provide a more complete understanding of the fundamental controlling processes in combustion by identifying simpler one-dimensional systems to eliminate the complex interactions between the buoyant flow and the energy feedback to the reaction zone to provide realistic simulation of the fire risk in manned spacecraft and to enable practical simulation of the gravitational environment experienced by reacting systems in future spacecraft. Over the past two decades, low-gravity combustion research has focused primarily on increasing our understanding of fundamental combustion processes (e.g. droplet combustion, soot, flame spread, smoldering, and gas-jet flames). This research program was highly successful and was aided by synergistic programs in Europe and in Japan. Overall improvements were made in our ability to model droplet combustion in spray combustors (e.g. jet engines), predict flame spread, predict soot production, and detect and prevent spacecraft fires. These results provided a unique dataset that supports both an active research discipline and also spacecraft fire safety for current and future spacecraft. These experiments have been conducted using the Combustion Integrated Rack (CIR), the Microgravity Science Glovebox and the Express Rack. In this paper, we provide an overview of the earlier space shuttle experiments, the recent ISS combustion experiments in addition to the studies planned for the future. Experiments in combustion include topics such as droplet combustion, gaseous diffusion flames, solid fuels, premixed flame studies, fire safety, and super critical oxidation processes.

Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

Energy Technology Data Exchange (ETDEWEB)

Rojas-Chavez, H., E-mail: uu_gg_oo@yahoo.com.mx [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico) and Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo (Mexico); Reyes-Carmona, F. [Facultad de Quimica - UNAM, Circuito de la Investigacion Cientifica s/n, C.U. Del. Coyoacan (Mexico); Jaramillo-Vigueras, D. [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico)

2011-10-15

Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

International Nuclear Information System (INIS)

Rojas-Chavez, H.; Reyes-Carmona, F.; Jaramillo-Vigueras, D.

2011-01-01

Highlights: → PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. → During high-energy milling oxygen has to be chemically reduced from the lead oxide. → Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

Investigation of reactions and species dominating low temperature combustion - Final report

Energy Technology Data Exchange (ETDEWEB)

Radi, P.; Knopp, G.; Johnson, M.; Boedi, A.; Gerber, T.

2009-12-15

This report for the Swiss Federal Office of Energy (SFOE) presents the results of work done at the Paul Scherrer Institute (PSI) in Switzerland. The project 'Investigation of reactions and species dominating low temperature combustion' involves the characterisation of species that govern ignition. A base established for the spectroscopic investigation of peroxy radicals is discussed. The two-fold aim of this project is discussed which includes the measurement of molecular features such as binding energies and dissociation patterns of well-studied and spectroscopically accessible molecules and radicals as well as the application of the measurement techniques to alkyl peroxy radicals. This was done in order to improve the database of a class of molecules playing a dominant role in combustion and atmospheric chemistry. Several experimental techniques that are to be developed to achieve these aims are looked at. Achievements made are discussed and future work to be carried out is noted.

THE REACTION TO FIRE TEST FOR FIRE RETARDANT AND FOR COMBUSTIBLE MATERIAL

Directory of Open Access Journals (Sweden)

Adelaida FANFAROVÁ

2016-12-01

Full Text Available Currently the natural materials become popular building material for houses, buildings and recreational property. The risk of fires in residential timber construction or eco houses cannot be completely ruled out, therefore there is a need for proper and correct implementing preventive measures and application of all available solutions, which may reduce the risk of fire as far as possible, to slow down the combustion process, to protect the life of people, animals and also the building itself until arrival members of the Fire and Rescue Services. Fireproofing of combustible materials is a specific area of fire protection. For scientific research as well as for real-life practice, not only their structural and physical properties, but also fire-technical characteristics are really important. The present researchers mostly focus on fire-retardant treatment of wood that is why the authors of this contribution focused on a different combustible material. This research article presents the experimental testing and examination of the reaction to fire test of the selected thermal insulation of hemp fiber that was impregnated by the selected fire retardant in laboratory conditions.

Contribution to the modelling of gas-solid reactions and reactors

International Nuclear Information System (INIS)

Patisson, F.

2005-09-01

Gas-solid reactions control a great number of major industrial processes involving matter transformation. This dissertation aims at showing that mathematical modelling is a useful tool for both understanding phenomena and optimising processes. First, the physical processes associated with a gas-solid reaction are presented in detail for a single particle, together with the corresponding available kinetic grain models. A second part is devoted to the modelling of multiparticle reactors. Different approaches, notably for coupling grain models and reactor models, are illustrated through various case studies: coal pyrolysis in a rotary kiln, production of uranium tetrafluoride in a moving bed furnace, on-grate incineration of municipal solid wastes, thermogravimetric apparatus, nuclear fuel making, steel-making electric arc furnace. (author)

Synthesis and characterization of CaTiO3 powder by combustion synthesis process

International Nuclear Information System (INIS)

Jung, C. W.; Shin, H. C.; Park, J. Y.; Lee, H. G.; Kim, H. Y.; Hong, K. W.

2000-01-01

Synroc is considered as a one of the most promising candidate for HLW solidification. CaTiO 3 , perovskite, which is a component of Synroc, can immobilize lanthanide and actinides by forming solid solutions. Generally most of the radioactive wastes elements were treated as a nitrate form. Therefore, the combustion process using metal nitrates as reactant materials can be easily applied to immobilize the radioactive waste elements. In this study, the feasibility of preparing fine, single-phase powders of multi-component oxide by a combustion process was investigated. Generally, the powder synthesized by combustion process showed different characteristics depending on the type and amount of fuel. And the spherical CaTiO 3 particles were directly prepared from the aqueous solution by an ultrasonic mist combustion process using an ultrasonic nebulizers as mist generators. The particles prepared with simple spray pyrolysis method using nitrate solution without fuel as precursor solution showed porous and hollow morphology, while the particles prepared with precursor solutions containing fuel showed dense solid morphology. Among various kinds of fuel tested, glycine showed the best result in reaction kinetics and crystalline phase purity

Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen

Energy Technology Data Exchange (ETDEWEB)

Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang [Institute of Photonic Technology, Laser Diagnostics, Albert-Einstein-Str. 9, 07745 Jena (Germany); Eigenbrod, Christian; Klinkov, Konstantin [Center of Applied Space Technology and Microgravity, University Bremen, Am Fallturm, 28359 Bremen (Germany); Larionov, Mikhail; Giesen, Adolf; Stolzenburg, Christian [Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, 70569 Stuttgart (Germany)

2014-03-15

We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM{sub 00}) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic around 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.

New class of combustion processes

International Nuclear Information System (INIS)

Merzhanov, A.G.; Borovinskaya, I.P.

1975-01-01

A short review is given of the results of work carried out since 1967 on studying the combustion processes caused by the interaction of chemical elements in the condensed phase and leading to the formation of refractory compounds. New phenomena and processes are described which are revealed when investigating the combustion of the systems of this class, viz solid-phase combustion, fast combustion in the condensed phase, filtering combustion, combustion in liquid nitrogen, spinning combustion, self-oscillating combustion, and repeated combustion. A new direction in employment of combustion processes is discussed, viz. a self-propagating high-temperature synthesis of refractory nitrides, carbides, borides, silicides and other compounds

Manifold methods for methane combustion

Energy Technology Data Exchange (ETDEWEB)

Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

1995-10-01

Great progresses have been made in combustion research, especially, the computation of laminar flames and the probability density function (PDF) method in turbulent combustion. For one-dimensional laminar flames, by considering the transport mechanism, the detailed chemical kinetic mechanism and the interactions between these two basic processes, today it is a routine matter to calculate flame velocities, extinction, ignition, temperature, and species distributions from the governing equations. Results are in good agreement with those obtained for experiments. However, for turbulent combustion, because of the complexities of turbulent flow, chemical reactions, and the interaction between them, in the foreseeable future, it is impossible to calculate the combustion flow field by directly integrating the basic governing equations. So averaging and modeling are necessary in turbulent combustion studies. Averaging, on one hand, simplifies turbulent combustion calculations, on the other hand, it introduces the infamous closure problems, especially the closure problem with chemical reaction terms. Since in PDF calculations of turbulent combustion, the averages of the chemical reaction terms can be calculated, PDF methods overcome the closure problem with the reaction terms. It has been shown that the PDF method is a most promising method to calculate turbulent combustion. PDF methods have been successfully employed to calculate laboratory turbulent flames: they can predict phenomena such as super equilibrium radical levels, and local extinction. Because of these advantages, PDF methods are becoming used increasingly in industry combustor codes.

A miniature CSTR cascade for continuous flow of reactions containing solids

OpenAIRE

Mo, Yiming; Jensen, Klavs F

2016-01-01

Continuous handling of solids creates challenges for realizing continuous production of pharmaceuticals and fine chemicals. We present a new miniature continuous stirred-tank reactor (CSTR) cascade to handle solid-forming reactions in flow. Single-phase residence time distribution (RTD) measurements of the CSTR cascade reveal nearly ideal CSTR mixing behavior of the individual units. Consistency of experimental and predicted conversions of a Diels–Alder reaction further confirms the CSTR perf...

Chemical cleavage reactions of DNA on solid support: application in mutation detection

Directory of Open Access Journals (Sweden)

Cotton Richard GH

2003-05-01

Full Text Available Abstract Background The conventional solution-phase Chemical Cleavage of Mismatch (CCM method is time-consuming, as the protocol requires purification of DNA after each reaction step. This paper describes a new version of CCM to overcome this problem by immobilizing DNA on silica solid supports. Results DNA test samples were loaded on to silica beads and the DNA bound to the solid supports underwent chemical modification reactions with KMnO4 (potassium permanganate and hydroxylamine in 3M TEAC (tetraethylammonium chloride solution. The resulting modified DNA was then simultaneously cleaved by piperidine and removed from the solid supports to afford DNA fragments without the requirement of DNA purification between reaction steps. Conclusions The new solid-phase version of CCM is a fast, cost-effective and sensitive method for detection of mismatches and mutations.

Combustion and fuel loading characteristics of Hanford Site transuranic solid waste

International Nuclear Information System (INIS)

Greenhalgh, W.O.

1994-01-01

The Waste Receiving and Processing (WRAP) Facility is being designed for construction in the north end of the Central Waste Complex. The WRAP Facility will receive, store, and process radioactive solid waste of both transuranic (TRU) and mixed waste (mixed radioactive-chemical waste) categories. Most of the waste is in 208-L (55-gal) steel drums. Other containers such as wood and steel boxes, and various sized drums will also be processed in the facility. The largest volume of waste and the type addressed in this report is TRU in 208-L (55-gal) drums that is scheduled to be processed in the Waste Receiving and Processing Facility Module 1 (WRAP 1). Half of the TRU waste processed by WRAP 1 is expected to be retrieved stored waste and the other half newly generated waste. Both the stored and new waste will be processed to certify it for permanent storage in the Waste Isolation Pilot Plant (WIPP) or disposal. The stored waste will go through a process of retrieval, examination, analysis, segregation, repackaging, relabeling, and documentation before certification and WIPP shipment. Newly generated waste should be much easier to process and certify. However, a substantial number of drums of both retrievable and newly generated waste will require temporary storage and handling in WRAP. Most of the TRU waste is combustible or has combustible components. Therefore, the presence of a substantial volume of drummed combustible waste raises concern about fire safety in WRAP and similar waste drum storage facilities. This report analyzes the fire related characteristics of the expected WRAP TRU waste stream

Structural and morphological characterization of TiO2 powders prepared using Pechini and combustion reaction

International Nuclear Information System (INIS)

Ribeiro, P.C.; Almeida, E.P.; Costa, A.C.F.M. da; Lira, H.L.; Kiminami, R.H.G.A.

2010-01-01

TiO 2 is a semiconductor oxide and polymorphic and can exist in three crystallographic forms: anatase, rutile and broquita, and forms anatase and rutile are the major interests in scientific research. Thus, this study aims to synthesize TiO 2 by Pechini methods and combustion reaction and to evaluate the influence of synthesis methods in structural and morphological characteristics of the samples. The nanopowders were characterized by X-ray diffraction, nitrogen adsorption, and particle size distribution and scanning electron microscopy. The results of X-ray diffraction showed that the samples obtained by the Pechini method showed the single phase anatase with crystallite size of 20 nm and surface area of 49.44 m 2 /g, whereas the samples synthesized by combustion reaction using glycine as fuel showed the rutile phase as major phase and traces of anatase phase, with crystallite size of 65 nm and surface area 4.34 m 2 /g. (author)

Synthesis of Li2MO3 (M = Ti or Zr) by the combustion method

International Nuclear Information System (INIS)

Cruza, D.; Bulbuliana, S.; Cruza, D.; Pfeifferc, H.

2006-01-01

The advantages and disadvantages of the combustion method to prepare Li 2 TiO 3 and Li 2 ZrO 3 ceramics were studied. Firstly, the ceramic powders were prepared by the combustion process using LiOH, MO 2 (where M=Ti or Zr) and urea in different molar ratios (from 2:1:3 to 3:1:3) at different temperatures for 5 minutes. Li 2 TiO 3 and Li 2 ZrO 3 were also obtained by the solid-state method, and the results were compared with those obtained by the combustion process. The powders were characterized by X-ray diffraction and scanning electron microscopy. It was found that the combustion process reduces the synthesis time of Li 2 TiO 3 (1 minute at 750 C), but it does not have any advantage on producing Li 2 ZrO 3 , due to thermodynamic factors. On the other hand, the combustion process produces carbon contaminants in the solids. It was necessary to add excess of lithium hydroxide, in order to compensate the quantity of Li sublimated during the production of the ceramics. Finally, it seems that both reactions follow the same mechanism, which is determined by the lithium diffusion into the metal oxides. (authors)

HTP kinetics studies on isolated elementary combustion reactions over wide temperature ranges

Energy Technology Data Exchange (ETDEWEB)

Fontijn, A.; Adusei, G.Y.; Hranisavlevic, J.; Bajaj, P.N. [Rensselaer Polytechnic Institute, Troy, NY (United States)

1993-12-01

The goals of this project are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions, (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. Experimental measurements are made mainly by using the pseudo-static HTP (high-temperature photochemistry) technique. While continuing rate coefficient measurements, further aspects of kinetics research are being explored. Thus, starting from the data obtained, a method for predicting the temperature dependence of rate coefficients of oxygen-atom olefin experiment and confirms the underlying mechanistic assumptions. Mechanistic information of another sort, i.e. by product analysis, has recently become accessible with the inauguration of our heated flow tube mass spectrometer facility; early results are reported here. HTP experiments designed to lead to measurements of product channels by resonance fluorescence have started.

Establishment of Combustion Model for Isooctane HCCI Marine Diesel Engine and Research on the Combustion Characteristic

Directory of Open Access Journals (Sweden)

Li Biao

2016-01-01

Full Text Available The homogeneous charge compression ignition (HCCI combustion mode applied in marine diesel engine is expected to be one of alternative technologies to decrease nitrogen oxide (NOX emission and improve energy utilization rate. Applying the chemical-looping combustion (CLC mechanism inside the cylinder, a numerical study on the HCCI combustion process is performed taking a marine diesel engine as application object. The characteristic feature of combustion process is displayed. On this basis, the formation and emission of NOX are analyzed and discussed. The results indicate that the HCCI combustion mode always exhibit two combustion releasing heats: low-temperature reaction and high-temperature reaction. The combustion phase is divided into low-temperature reaction zone, high-temperature reaction zone and negative temperature coefficient (NTC zone. The operating conditions of the high compression ratio, high intake air temperature, low inlet pressure and small excess air coefficient would cause the high in-cylinder pressure which often leads engine detonation. The low compression ratio, low intake air temperature and big excess air coefficient would cause the low combustor temperature which is conducive to reduce NOX emissions. These technological means and operating conditions are expected to meet the NOX emissions limits in MARPOL73/78 Convention-Annex VI Amendment.

Reaction diffusion and solid state chemical kinetics handbook

CERN Document Server

Dybkov, V I

2010-01-01

This monograph deals with a physico-chemical approach to the problem of the solid-state growth of chemical compound layers and reaction-diffusion in binary heterogeneous systems formed by two solids; as well as a solid with a liquid or a gas. It is explained why the number of compound layers growing at the interface between the original phases is usually much lower than the number of chemical compounds in the phase diagram of a given binary system. For example, of the eight intermetallic compounds which exist in the aluminium-zirconium binary system, only ZrAl3 was found to grow as a separate

Strobes: An oscillatory combustion

NARCIS (Netherlands)

Corbel, J.M.L.; Lingen, J.N.J. van; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

2012-01-01

Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

International Nuclear Information System (INIS)

Sun, Rui; Ismail, Tamer M.; Ren, Xiaohan; Abd El-Salam, M.

2015-01-01

Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

Energy Technology Data Exchange (ETDEWEB)

Sun, Rui, E-mail: Sunsr@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Ismail, Tamer M., E-mail: temoil@aucegypt.edu [Department of Mechanical Engineering, Suez Canal University, Ismailia (Egypt); Ren, Xiaohan [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Abd El-Salam, M. [Department of Basic Science, Cairo University, Giza (Egypt)

2015-05-15

Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.

Oxidation rates of carbon and nitrogen in char residues from solid fuels

Energy Technology Data Exchange (ETDEWEB)

Karlstroem, O.

2013-06-01

Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O{sub 2}. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars

Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review

Directory of Open Access Journals (Sweden)

Ping Wang

2015-09-01

Full Text Available Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC and chemical-looping gasification (CLG have the potential to be used to generate power, chemicals, and liquid fuels. Chemical-looping is an oxygen transporting process using oxygen carriers. Recently, attention has focused on solid fuels such as coal. Coal chemical-looping reactions are more complicated than gaseous fuels due to coal properties (like mineral matter and the complex reaction pathways involving solid fuels. The mineral matter/ash and sulfur in coal may affect the activity of oxygen carriers. Oxygen carriers are the key issue in chemical-looping processes. Thermogravimetric analysis (TGA has been widely used for the development of oxygen carriers (e.g., oxide reactivity. Two proposed processes for the CLC of solid fuels are in-situ Gasification Chemical-Looping Combustion (iG-CLC and Chemical-Looping with Oxygen Uncoupling (CLOU. The objectives of this review are to discuss various chemical-looping processes with coal, summarize TGA applications in oxygen carrier development, and outline the major challenges associated with coal chemical-looping in iG-CLC and CLOU.

Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

Directory of Open Access Journals (Sweden)

Roberto Rosa

2014-05-01

Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

Numerical simulation of combustion and soot under partially premixed combustion of low-octane gasoline

KAUST Repository

An, Yanzhao

2017-09-23

In-cylinder combustion visualization and engine-out soot particle emissions were investigated in an optical diesel engine fueled with low octane gasoline. Single injection strategy with an early injection timing (−30 CAD aTDC) was employed to achieve partially premixed combustion (PPC) condition. A high-speed color camera was used to record the combustion images for 150 cycles. The regulated emission of carbon dioxide, carbon monoxide, nitrogen oxides and soot mass concentration were measured experimentally. Full cycle engine simulations were performed using CONVERGE™ and the simulation results matched with the experimental results. The in-cylinder soot particle evolution was performed by coupling a reduced toluene reference fuel mechanism including the PAHs formation/oxidation reactions with particulate size mimic model. The results showed that PPC presents typical stratified combustion characteristics, which is significantly different from the conventional diesel spray-driven combustion. The in-cylinder temperature and equivalence ratio overlaid with soot-NO formation regime revealed that PPC operating condition under study mostly avoided the main sooting conditions throughout the entire combustion. The evaluation of temperature distribution showed formaldehyde could be regarded as an indicator for low temperature reactions, while hydroxyl group represents the high temperature reactions. Soot evolution happened during the combustion process, hydroxyl radicals promoted the soot oxidation.

Numerical simulation of combustion and soot under partially premixed combustion of low-octane gasoline

KAUST Repository

An, Yanzhao; Jaasim, Mohammed; Vallinayagam, R.; Vedharaj, S.; Im, Hong G.; Johansson, Bengt.

2017-01-01

In-cylinder combustion visualization and engine-out soot particle emissions were investigated in an optical diesel engine fueled with low octane gasoline. Single injection strategy with an early injection timing (−30 CAD aTDC) was employed to achieve partially premixed combustion (PPC) condition. A high-speed color camera was used to record the combustion images for 150 cycles. The regulated emission of carbon dioxide, carbon monoxide, nitrogen oxides and soot mass concentration were measured experimentally. Full cycle engine simulations were performed using CONVERGE™ and the simulation results matched with the experimental results. The in-cylinder soot particle evolution was performed by coupling a reduced toluene reference fuel mechanism including the PAHs formation/oxidation reactions with particulate size mimic model. The results showed that PPC presents typical stratified combustion characteristics, which is significantly different from the conventional diesel spray-driven combustion. The in-cylinder temperature and equivalence ratio overlaid with soot-NO formation regime revealed that PPC operating condition under study mostly avoided the main sooting conditions throughout the entire combustion. The evaluation of temperature distribution showed formaldehyde could be regarded as an indicator for low temperature reactions, while hydroxyl group represents the high temperature reactions. Soot evolution happened during the combustion process, hydroxyl radicals promoted the soot oxidation.

Gas-Solid Reaction Properties of Fluorine Compounds and Solid Adsorbents for Off-Gas Treatment from Semiconductor Facility

Directory of Open Access Journals (Sweden)

Shinji Yasui

2012-01-01

Full Text Available We have been developing a new dry-type off-gas treatment system for recycling fluorine from perfluoro compounds present in off-gases from the semiconductor industry. The feature of this system is to adsorb the fluorine compounds in the exhaust gases from the decomposition furnace by using two types of solid adsorbents: the calcium carbonate in the upper layer adsorbs HF and converts it to CaF2, and the sodium bicarbonate in the lower layer adsorbs HF and SiF4 and converts them to Na2SiF6. This paper describes the fluorine compound adsorption properties of both the solid adsorbents—calcium carbonate and the sodium compound—for the optimal design of the fixation furnace. An analysis of the gas-solid reaction rate was performed from the experimental results of the breakthrough curve by using a fixed-bed reaction model, and the reaction rate constants and adsorption capacity were obtained for achieving an optimal process design.

Environmental performance of the Kvaerner BFB boilers for MSW combustion -- Analysis of gaseous emissions and solid residues

International Nuclear Information System (INIS)

Lundberg, M.; Hagman, U.; Andersson, B.A.; Olofsson, J.

1997-01-01

Kvaerner Pulping AB (formerly Kvaerner EnviroPower AB) has, due to the stringent demands on emissions performance, developed a state-of-the-art bubbling fluidized bed boiler (BFB) designed for waste fuel firing with very low emissions to the air. A complete evaluation of the environmental performance of the Kvaerner BFB technique for MSW combustion is now possible thanks to a thorough characterization study of the solid residues from the Lidkoeping plant. This paper gives an overall mapping of the emissions performance. Data from the operating plants on solid residue characteristics and leachability, heavy metal and dioxin emissions, nitrogen oxides, carbon monoxide, acid gases, and other emissions to air are presented. Comparisons are made with legislative limits and data from the mass burning technique. It is concluded that the emissions are low compared both with data from traditional mass burn incinerators and with legislative limits in the USA and Europe. Furthermore, the bottom and cyclone ash characteristics are shown not to cause any particular problem from an environmental point of view, and that the leachability is well below the existing legislative limits in Europe and the USA. The results show that fluidized bed combustion of municipal solid waste is a very competitive alternative to the traditional mass burning technique in every respect

Nitric oxide reduction in coal combustion: role of char surface complexes in heterogeneous reactions.

Science.gov (United States)

Arenillas, Ana; Rubiera, Fernando; Pis, José J

2002-12-15

Nitrogen oxides are one of the major environmental problems arising from fossil fuel combustion. Coal char is relatively rich in nitrogen, and so this is an important source of nitrogen oxides during coal combustion. However, due to its carbonaceous nature, char can also reduce NO through heterogeneous reduction. The objectives of this work were on one hand to compare NO emissions from coal combustion in two different types of equipment and on the other hand to study the influence of char surface chemistry on NO reduction. A series of combustion tests were carried out in two different scale devices: a thermogravimetric analyzer coupled to a mass spectrometer and an FTIR (TG-MS-FTIR) and a fluidized bed reactor with an on line battery of analyzers. The TG-MS-FTIR system was also used to perform a specific study on NO heterogeneous reduction reactions using chars with different surface chemistry. According to the results obtained, it can be said that the TG-MS-FTIR system provides valuable information about NO heterogeneous reduction and it can give good trends of the behavior in other combustion equipments (i.e., fluidized bed combustors). It has been also pointed out that NO-char interaction depends to a large extent on temperature. In the low-temperature range (800 degrees C), a different mechanism is involved in NO heterogeneous reduction, the nature of the carbon matrix being a key factor.

Combustion characteristics and turbulence modeling of swirling reacting flow in solid fuel ramjet

Science.gov (United States)

Musa, Omer; Xiong, Chen; Changsheng, Zhou

2017-10-01

This paper reviews the historical studies have been done on the solid-fuel ramjet engine and difficulties associated with numerical modeling of swirling flow with combustible gases. A literature survey about works related to numerical and experimental investigations on solid-fuel ramjet as well as using swirling flow and different numerical approaches has been provided. An overview of turbulence modeling of swirling flow and the behavior of turbulence at streamline curvature and system rotation are presented. A new and simple curvature/correction factor is proposed in order to reduce the programming complexity of SST-CC turbulence model. Finally, numerical and experimental investigations on the impact of swirling flow on SFRJ have been carried out. For that regard, a multi-physics coupling code is developed to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. The connected-pipe test facility is used to carry out the experiments. The results showed a positive impact of swirling flow on SFRJ along with, three correlations are proposed.

Effect of urea on PCDD/F formation during combustion of coal and olive kernels in a pilot scale boiler

Energy Technology Data Exchange (ETDEWEB)

Skodras, G. [Laboratory of Environmental and Energy Processes, Thermi-Thessaloniki (Greece). Chemical Process Engineering Research Institute]|[Institute for Solid Fuels Technology and Applications, Center for Research and Technology Hellas, Ptolemais (Greece)]|[Aristotle Univ. of Thessaloniki (Greece). Dept. of Chemical Engineering; Palladas, A.; Sakellaropoulos, G.P. [Laboratory of Environmental and Energy Processes, Thermi-Thessaloniki (Greece). Chemical Process Engineering Research Institute]|[Institute for Solid Fuels Technology and Applications, Center for Research and Technology Hellas, Ptolemais (Greece)

2004-09-15

Solid fuel combustion is a major source of Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) that are highly toxic compounds even in trace amounts. In addition, the complex conditions of the flue gases could favor, in same cases, PCDD/F formation. Thus, the presence of chlorine and metal catalysts (i.e. copper) in the flue gases, could lead, through heterogeneous reactions, to PCDD/F formation between 250-400 C. Three major theories have been established to elucidate the formation of PCDD/Fs in combustion systems: PCDD/Fs are already present in the incoming feed and are incompletely destroyed or transformed during combustion PCDD/Fs can be formed during combustion and PCDD/Fs can be formed by de novo mechanism that is in the low-temperature post-combustion zone of incinerators through some heterogeneous catalytic reactions that occur in the flue gas-fly ash environment. Post-combustion and precombustion techniques have been elaborated to minimize the PCDD/F emissions. Post combustion techniques utilize gas-cleaning devices to capture or destroy them after formation, while certain compounds could be added in the raw, prior the combustion zone, to inhibit PCDD/Fs formation (pre-combustion measures). In his work the PCDD/F emissions during the combustion of lignite, olive kernel and blends were measured and the efficiency of urea to act as potential inhibitor in PCDD/F formation was investigated also.

The kinetics of combustion of chars derived from sewage sludge

Energy Technology Data Exchange (ETDEWEB)

J.S. Dennis; R.J. Lambert; A.J. Milne; S.A. Scott; A.N. Hayhurst [University of Cambridge, Cambridge (United Kingdom). Department of Chemical Engineering

2005-02-01

Experiments have been conducted to determine the combustion characteristics of sewage sludge chars in electrically heated beds of silica sand fluidised by air. The effects of the initial size of the char particles, the temperature of the bed and the concentration of (O{sub 2}) in the fluidising gas were investigated. Also, the temperatures of burning particles were measured with embedded thermocouples. The kinetics of combustion were measured at temperatures low enough for the CO formed by initial reaction between the carbon and oxygen to burn at some distance away from the particle. It is probable that the lower value is closer to the actual value, thought to be 135{+-}15 kJ/mol, reflecting the catalytic nature of the ash skeleton on which the carbon is supported. It was possible to obtain good agreement between measured burnout times and those predicted using the grain model of Szekely J, Evans JW, Sohn HY. Gas-solid reactions. New York: Academic Press; 1976, for the case where the kinetics are controlled by a combination of: (i) external mass transfer of oxygen from the particulate phase to the external surface of the burning char particle, (ii) diffusion of oxygen from the external surface into the porous matrix to the surfaces of grains, of which the solid is composed, and (iii) diffusion of oxygen into the microporous grains, where reaction occurs with the carbon. It was found that, for particles with diameters of 2 mm or larger, the initial rates of reaction, for bed temperatures in excess of 750{degree}C, are dominated by external mass transfer. 22 refs., 8 figs., 1 tab.

Direct sulfation of limestone based on oxy-fuel combustion technology

Energy Technology Data Exchange (ETDEWEB)

Chen, C.M.; Zhao, C.S.; Liu, S.T.; Wang, C.B. [North China Electric Power University, Baoding (China)

2009-10-15

With limestone as the sorbent, the sulfation reaction can proceed via two different routes depending on whether calcination of the limestone takes place under the given reaction conditions. The direct sulfation reaction is defined as the sulfation reaction between sulfur dioxide (SO{sub 2}) and limestone in an uncalcined state. This reaction, based on oxyfuel combustion technology, was studied by thermogravimetric analysis. Surface morphologies of the limestone particles after sulfation were examined by a scanning electron microscope. Results show that there are more pores or gaps in the product layer formed by direct sulfation of limestone than by indirect sulfation, which can be attributed to the generation of carbon dioxide (CO{sub 2}) at a reaction interface. Compared with indirect sulfation, direct sulfation of limestone can yield much higher conversion and has a much higher reaction rate. For direct sulfation, the greater porosity in the product layer greatly reduces the solid-state ion diffusion distance, resulting in a higher reaction rate and higher conversion.

Solid-phase vibrational redox reactions in coordinated oxides

International Nuclear Information System (INIS)

Kostikova, G.P.; Korol'kov, D.V.; Kostikov, Yu.P.

1996-01-01

The properties of multicomponent oxides (YBa 2 Cu 3 O 7-x , etc.), incorporating different valency forms of each of two (or more) different elements have been compared with the properties of the known chemical systems, where vibrational (periodic) redox-reactions are realized a fortiori. The essence of the new theoretical concept suggested consists in the following: high-T c superconductivity of the complex oxides and similar compounds originates from vibrational redox reaction proceeding in solid phase and involving different valency atoms of every element

Ambient Mechanochemical Solid-State Reactions of Carbon Nanotubes and Their Reactions via Covalent Coordinate Bond in Solution

Science.gov (United States)

Kabbani, Mohamad A.

In its first part, this thesis deals with ambient mechanochemical solid-state reactions of differently functionalized multiple walled carbon nanotubes (MWCNTs) while in its second part it investigates the cross-linking reactions of CNTs in solution via covalent coordinate bonds with transitions metals and carboxylate groups decorating their surfaces. In the first part a series of mechanochemical reactions involving different reactive functionalities on the CNTs such as COOH/OH, COOH/NH2 and COCl/OH were performed. The solid-state unzipping of CNTs leading to graphene formation was confirmed using spectroscopic, thermal and electron microscopy techniques. The non-grapheme products were established using in-situ quadruple mass spectroscopy. The experimental results were confirmed by theoretical simulation calculations using the 'hot spots' protocol. The kinetics of the reaction between MWCNT-COOH and MWCNT-OH was monitored using variable temperature Raman spectroscopy. The low activation energy was discussed in terms of hydrogen bond mediated proton transfer mechanism. The second part involves the reaction of MWCNTII COOH with Zn (II) and Cu (II) to form CNT metal-organic frame (MOFs) products that were tested for their effective use as counter-electrodes in dyes sensitized solar cells (DSSC). The thesis concludes by the study of the room temperature reaction between the functionalized graphenes, GOH and G'-COOH followed by the application of compressive loads. The 3D solid graphene pellet product ( 0.6gm/cc) is conductive and reflective with a 35MPa ultimate strength as compared to 10MPa strength of graphite electrode ( 2.2gm/cc).

Studies of combustion reactions at the state-resolved differential cross section level

Energy Technology Data Exchange (ETDEWEB)

Houston, P.L.; Suits, A.G.; Bontuyan, L.S.; Whitaker, B.J. [Cornell Univ., Ithaca, NY (United States)

1993-12-01

State-resolved differential reaction cross sections provide perhaps the most detailed information about the mechanism of a chemical reaction, but heretofore they have been extremely difficult to measure. This program explores a new technique for obtaining differential cross sections with product state resolution. The three-dimensional velocity distribution of state-selected reaction products is determined by ionizing the appropriate product, waiting for a delay while it recoils along the trajectory imparted by the reaction, and finally projecting the spatial distribution of ions onto a two dimensional screen using a pulsed electric field. Knowledge of the arrival time allows the ion position to be converted to a velocity, and the density of velocity projections can be inverted mathematically to provide the three-dimensional velocity distribution for the selected product. The main apparatus has been constructed and tested using photodissociations. The authors report here the first test results using crossed beams to investigate collisions between Ar and NO. Future research will both develop further the new technique and employ it to investigate methyl radical, formyl radical, and hydrogen atom reactions which are important in combustion processes. The authors intend specifically to characterize the reactions of CH{sub 3} with H{sub 2} and H{sub 2}CO; of HCO with O{sub 2}; and of H with CH{sub 4}, CO{sub 2}, and O{sub 2}.

Electron stimulated reactions of methyl iodide coadsorbed with amorphous solid water

International Nuclear Information System (INIS)

Perry, C. C.; Faradzhev, N. S.; Madey, T. E.; Fairbrother, D. H.

2007-01-01

The electron stimulated reactions of methyl iodide (MeI) adsorbed on and suspended within amorphous solid water (ice) were studied using a combination of postirradiation temperature programmed desorption and reflection absorption infrared spectroscopy. For MeI adsorbed on top of amorphous solid water (ice), electron beam irradiation is responsible for both structural and chemical transformations within the overlayer. Electron stimulated reactions of MeI result principally in the formation of methyl radicals and solvated iodide anions. The cross section for electron stimulated decomposition of MeI is comparable to the gas phase value and is only weakly dependent upon the local environment. For both adsorbed MeI and suspended MeI, reactions of methyl radicals within MeI clusters lead to the formation of ethane, ethyl iodide, and diiodomethane. In contrast, reactions between the products of methyl iodide and water dissociation are responsible for the formation of methanol and carbon dioxide. Methane, formed as a result of reactions between methyl radicals and either parent MeI molecules or hydrogen atoms, is also observed. The product distribution is found to depend on the film's initial chemical composition as well as the electron fluence. Results from this study highlight the similarities in the carbon-containing products formed when monohalomethanes coadsorbed with amorphous solid water are irradiated by either electrons or photons

Pyrolysis and combustion kinetics of lycopodium particles in thermogravimetric analysis

Institute of Scientific and Technical Information of China (English)

Seyed Alireza Mostafavi; Sadjad Salavati; Hossein Beidaghy Dizaji; Mehdi Bidabadi

2015-01-01

Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion properties, of which microscopic images show that these particles have spherical shapes with identical diameters of 31 μm. The measured density of these particles is 1.0779 g/cm2. Lycopodium particles contain 64.06% carbon, 25.56% oxygen, 8.55% hydrogen and 1.83% nitrogen, and no sulfur. Thermogravimetric analysis in the nitrogen environment indicates that the maximum of particle mass reduction occurs in the temperature range of 250−550 °C where the maximum mass reduction in the DTG diagrams also occurs in. In the oxygen environment, an additional peak can also be observed in the temperature range of 500−600 °C, which points to solid phase combustion and ignition temperature of lycopodium particles. The kinetics of reactions is determined by curve fitting and minimization of error.

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Directory of Open Access Journals (Sweden)

David Greatrix

2015-02-01

Full Text Available The ability to predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms typically necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. On the mitigation side, one in practice sees the use of inert or reactive particles for the suppression of pressure wave development in the motor chamber flow. With the focus of the present study placed on reactive particles, a numerical internal ballistic model incorporating relevant elements, such as a transient, frequency-dependent combustion response to axial pressure wave activity above the burning propellant surface, is applied to the investigation of using aluminum particles within the central internal flow (particles whose surfaces nominally regress with time, as a function of current particle size, as they move downstream as a means of suppressing instability-related symptoms in a cylindrical-grain motor. The results of this investigation reveal that the loading percentage and starting size of the aluminum particles have a significant influence on reducing the resulting transient pressure wave magnitude.

Technological methods of reducing the emissions of nitrogen oxides during the combustion of solid fuel

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.

1981-01-01

For protecting the atmosphere from emissions of toxic NO /SUB x/ during combustion of fuel in boilers the amount of NO /SUB x/ can be reduced in the process of combustion, or the flue gases (FG) from the boiler can be cleaned. The latter method is bound up with the necessity for treatment of a large quantity of FG with a comparatively low concentration in them of nitrogen oxides, chemically stable and poorly soluble in water. The problem is complicated by the presence in the FG of SO /SUB x/, O/sub 2/, and solid particles. The method of purifying the FG is complicated and requires large capital investment and operating expenses. By laboratory studies in the All-Union Institute of Heat Engineering im. F.E. Dzerzhinskiy (VTI) it was established that thermal NO /SUB x/ is formed at a combustion temperature greater than or equal to 1550 /sup 0/C and that the 0/sub 2/ concentration and considerably less the temperature strongly affect NO /SUB x/ formation. On the basis of laboratory studies and industrial tests in the VTI, methods of reducing NO /SUB x/ emissions by large-scale boilers are recommended.

Effect of the container in the synthesis of the combustion reaction of ZnAl2O4

International Nuclear Information System (INIS)

Silva, D.A.R.; Cavalcanti, L.R.C.; Moura, A.L.S.; Rocha, M.L.; Neto, O.L.A.; Cabral, I.C.; Viana, K.M.S.; Costa, A.C.F.M.

2012-01-01

In the present work is a study on the influence of the container in the synthesis of the combustion reaction ZnAl 2 O 4 . Products of combustion obtained for both synthesis routes, were broken and sieved in 325 mesh (44μm). The powders resulting from two types of synthesis were characterized by X-ray diffraction and scanning electron microscopy. By means of XRD analysis showed the formation of the main phase of zinc aluminate spinel (Z) as phase the mineral guanine in the two procedures synthesis. By means of SEM analysis showed that in the procedure used the crucible metal zinc aluminate is introduced in the form of smaller agglomerates. Therefore, the container used in the synthesis of combustion influences the microstructure of the material synthesized. (author)

Development of plasma melting technology for treatment of low level radioactive waste. Pt. 9. Treatment method for combustible wastes

International Nuclear Information System (INIS)

Yasui, Shinji; Adachi, Kazuo; Amakawa, Masashi

1996-01-01

This paper describes the incineration method for the miscellaneous solid waste containing the low level radioactive combustibles (wood, PE, PVC) in a plasma furnace. The maximum weights of the respective combustibles to be fed into the plasma furnace and the incineration conditions for continuous feeding of the respective combustibles were examined experimentally. As a result, a experimental equation which expresses the maximum weights of the respective combustibles to be fed in reference to the residence time in the plasma furnace was obtained by using apparent reaction rate constants. Furthermore, a calculation method for the feeding intervals in reference to the weights of the combustibles fed each time was obtained for the continuous feeding in the plasma furnace, and the method was found to be consistent with experimental results. (author)

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

International Nuclear Information System (INIS)

Hayes, R.E.; Wanke, S.E.

2008-01-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

Energy Technology Data Exchange (ETDEWEB)

Hayes, R.E.; Wanke, S.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

2008-07-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs.

Influence of carbonation under oxy-fuel combustion flue gas on the leachability of heavy metals in MSWI fly ash.

Science.gov (United States)

Ni, Peng; Xiong, Zhuo; Tian, Chong; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

2017-09-01

Due to the high cost of pure CO 2 , carbonation of MSWI fly ash has not been fully developed. It is essential to select a kind of reaction gas with rich CO 2 instead of pure CO 2 . The CO 2 uptake and leaching toxicity of heavy metals in three typical types of municipal solid waste incinerator (MSWI) fly ash were investigated with simulated oxy-fuel combustion flue gas under different reaction temperatures, which was compared with both pure CO 2 and simulated air combustion flue gas. The CO 2 uptake under simulated oxy-fuel combustion flue gas were similar to that of pure CO 2 . The leaching concentration of heavy metals in all MSWI fly ash samples, especially in ash from Changzhou, China (CZ), decreased after carbonation. Specifically, the leached Pb concentration of the CZ MSWI fly ash decreased 92% under oxy-fuel combustion flue gas, 95% under pure CO 2 atmosphere and 84% under the air combustion flue gas. After carbonation, the leaching concentration of Pb was below the Chinese legal limit. The leaching concentration of Zn from CZ sample decreased 69% under oxy-fuel combustion flue gas, which of Cu, As, Cr and Hg decreased 25%, 33%, 11% and 21%, respectively. In the other two samples of Xuzhou, China (XZ) and Wuhan, China (WH), the leaching characteristics of heavy metals were similar to the CZ sample. The speciation of heavy metals was largely changed from the exchangeable to carbonated fraction because of the carbonation reaction under simulated oxy-fuel combustion flue gas. After carbonation reaction, most of heavy metals bound in carbonates became more stable and leached less. Therefore, oxy-fuel combustion flue gas could be a low-cost source for carbonation of MSWI fly ash. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling of the dynamical combustion of explosives: influence of mechanical properties; Modelisation de la combustion dynamique des explodifs: influence des proprietes mecaniques

Energy Technology Data Exchange (ETDEWEB)

Picart, D.; Pertuis, C. [CEA Le Ripault, 37 - Tours (France)

1996-12-31

Experimental observations performed during the combustion of solid explosives under pressure have shown an unexpected desensitization of the samples when damaged. A simplified method of combustion simulation inside a pressure cell is proposed in this study. The model used is based on the description of the mechanical behaviour of the solid phase. It allows to retrieve the overall experimental results, and in particular the occurrence of anomalous combustion modes. (J.S.) 8 refs.

Computational Fluid Dynamics Simulation of Combustion Instability in Solid Rocket Motor : Implementation of Pressure Coupled Response Function

OpenAIRE

S. Saha; D. Chakraborty

2016-01-01

Combustion instability in solid propellant rocket motor is numerically simulated by implementing propellant response function with quasi steady homogeneous one dimensional formulation. The convolution integral of propellant response with pressure history is implemented through a user defined function in commercial computational fluid dynamics software. The methodology is validated against literature reported motor test and other simulation results. Computed amplitude of pressure fluctuations ...

Modelling of turbulent combustion in the blast furnace raceway

Energy Technology Data Exchange (ETDEWEB)

Karvinen, R.; Maekiranta, R. [Tampere Univ. (Finland). Energy and Process Engineering

1996-12-31

The phenomena concerning coke-gas -suspension and simultaneous combustion of solid coke particles and residual fuel oil in a blast furnace raceway are modelled. The flow field of suspension is predicted by using the two fluid model, which is based on the Eulerian method, in the Phoenics code. The standard k-e -model of turbulence is used. Pyrolysis of oil droplets is calculated with the own coded subroutine, which is based on the Lagrangian approach. Gas phase reaction rate is assumed to be controlled by chemical kinetics. Radiative heat transfer is calculated by using the six-flux method. Heterogenous surface reactions are used for the coke particles. Calculations without coke combustion show that due to a poor mixing in the hot blast, pyrolysis gases of residual fuel oil have not time enough to react with oxygen. It is obvious that if combustion of coke particles is taken into account, the oxygen content in the blast decreases to such a level, that unburnt pyrolysis gases can flow out of the raceway causing problems. The distribution of coke void fraction has been succeeded to predict in the raceway domain. Coke particles fall from the upper part of the raceway to the hot blast forming locally high concentrations, which affect very strongly the oxygen distribution of the hot blast. (orig.) SULA 2 Research Programme; 10 refs.

Modelling of turbulent combustion in the blast furnace raceway

Energy Technology Data Exchange (ETDEWEB)

Karvinen, R; Maekiranta, R [Tampere Univ. (Finland). Energy and Process Engineering

1997-12-31

The phenomena concerning coke-gas -suspension and simultaneous combustion of solid coke particles and residual fuel oil in a blast furnace raceway are modelled. The flow field of suspension is predicted by using the two fluid model, which is based on the Eulerian method, in the Phoenics code. The standard k-e -model of turbulence is used. Pyrolysis of oil droplets is calculated with the own coded subroutine, which is based on the Lagrangian approach. Gas phase reaction rate is assumed to be controlled by chemical kinetics. Radiative heat transfer is calculated by using the six-flux method. Heterogenous surface reactions are used for the coke particles. Calculations without coke combustion show that due to a poor mixing in the hot blast, pyrolysis gases of residual fuel oil have not time enough to react with oxygen. It is obvious that if combustion of coke particles is taken into account, the oxygen content in the blast decreases to such a level, that unburnt pyrolysis gases can flow out of the raceway causing problems. The distribution of coke void fraction has been succeeded to predict in the raceway domain. Coke particles fall from the upper part of the raceway to the hot blast forming locally high concentrations, which affect very strongly the oxygen distribution of the hot blast. (orig.) SULA 2 Research Programme; 10 refs.

Combustion of Solids in Microgravity: Results from the BASS-II Experiment

Science.gov (United States)

Ferkul, Paul V.; Bhattacharjee, Subrata; Fernandez-Pello, Carlos; Miller, Fletcher; Olson, Sandra L.; Takahashi, Fumiaki; T’ien, James S.

2014-01-01

The Burning and Suppression of Solids-II (BASS-II) experiment was performed on the International Space Station. Microgravity combustion tests burned thin and thick flat samples, acrylic slabs, spheres, and cylinders. The samples were mounted inside a small wind tunnel which could impose air flow speeds up to 53 cms. The wind tunnel was installed in the Microgravity Science Glovebox which supplied power, imaging, and a level of containment. The effects of air flow speed, fuel thickness, fuel preheating, and oxygen concentration on flame appearance, growth, spread rate, and extinction were examined in both the opposed and concurrent flow configuration. The flames are quite sensitive to air flow speed in the range 0 to 5 cms. They can be sustained at very low flow speeds of less than 1 cms, when they become dim blue and stable. In this state they are not particularly dangerous from a fire safety perspective, but they can flare up quickly with a sudden increase in air flow speed. Including earlier BASS-I results, well over one hundred tests have been conducted of the various samples in the different geometries, flow speeds, and oxygen concentrations. There are several important implications related to fundamental combustion research as well as spacecraft fire safety. This work was supported by the NASA Space Life and Physical Sciences Research and Applications Division (SLPSRA).

Ultrasound assisted combustion synthesis of TiC in Al-Ti-C system.

Science.gov (United States)

Liu, Zhiwei; Rakita, Milan; Xu, Wilson; Wang, Xiaoming; Han, Qingyou

2015-11-01

This research investigated the effects of high-intensity ultrasound on the combustion synthesis of TiC particles in Al-Ti-C system. The process involved that high-intensity ultrasound was applied on the surface of a compacted Al-Ti-C pellet directly through a Nb probe during the thermal explosion reaction. By comparing with the sample without ultrasonic treatment, it was found that the thermal explosion reaction for synthesizing TiC phase could take place thoroughly in the ultrasonically treated sample. During the process of synthesizing TiC phase, the dissolution of solid graphite particles into the Al-Ti melt, as well as the nucleation and growth of TiC particles could be promoted effectively due to the effects of ultrasound, leading to an enhancement of the formation of TiC particles. Ultrasound assisted combustion synthesis as a simple and effective approach was proposed for synthesizing materials in this research. Copyright © 2015 Elsevier B.V. All rights reserved.

Fluidized bed combustion with the use of Greek solid fuels

Directory of Open Access Journals (Sweden)

Kakaras Emmanuel

2003-01-01

Full Text Available The paper is an overview of the results obtained up to date from the combustion and co-combustion activities with Greek brown coal in different installations, both in semi-industrial and laboratory scale. Combustion tests with Greek lignite were realized in three different Circulating Fluidized Bed Combustion (CFBC facilities. Low rank lignite was burned in a pilot scale facility of approx. 100kW thermal capacity, located in Athens (NTUA and a semi-industrial scale of 1.2 MW thermal capacity, located at RWE's power station Niederaussem in Germany. Co-combustion tests with Greek xylitic lignite and waste wood were carried out in the 1 MWth CFBC installation of AE&E, in Austria. Lab-scale co-combustion tests of Greek pre-dried lignite with biomass were accomplished in a bubbling fluidized bed in order to investigate ash melting problems. The obtained results of all aforementioned activities showed that fluidized bed is the appropriate combustion technology to efficiently exploit the low quality Greek brown coal either alone or in conjunction with biomass species.

A CFD model for biomass combustion in a packed bed furnace

Energy Technology Data Exchange (ETDEWEB)

Karim, Md. Rezwanul [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia); Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Ovi, Ifat Rabbil Qudrat [Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Naser, Jamal, E-mail: jnaser@swin.edu.au [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia)

2016-07-12

Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.

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...

Effect of bed particles to combustion of gases in fluidized bed

Energy Technology Data Exchange (ETDEWEB)

Raiko, R.; Wallen, V.; Etelaeaho, R.; Correia, S. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

1997-10-01

The objective of this project was to obtain experimental data on effects of sand particles to the combustion of gases. The effect of the surface area of the particles was tested using different sized particles. The fluidized bed reactor used in these experiments was a stainless-steel tube with an internal diameter of 42 mm surrounded by an electric heater. The test rig was built in the Laboratory of Energy and Process Engineering at Tampere University of Technology. In order to elucidate the possible changes of particle surface, microscopic and porosimetric studies were conducted with both fresh bed particles and used bed particles. These measurements indicate that carbon monoxide significantly reacts with oxygen in the particulate or emulsion phase of a fluidized bed, if the residence time is long enough. The reaction rate depends mainly on temperature, air coefficient, residence time and particle size of the solids. It seems that the combustion enhances if the average particle size increases. Whether this is caused by increased free path length or reduced specific surface area of the bed is yet unknown. The first might be more probable cause because the majority of reactions often took place in the freeboard right above the bed. It was clear that the bed hindered proper combustion in several cases. (orig.)

Distribution of Clay Minerals in Light Coal Fractions and the Thermal Reaction Products of These Clay Minerals during Combustion in a Drop Tube Furnace

Directory of Open Access Journals (Sweden)

Sida Tian

2016-06-01

Full Text Available To estimate the contribution of clay minerals in light coal fractions to ash deposition in furnaces, we investigated their distribution and thermal reaction products. The light fractions of two Chinese coals were prepared using a 1.5 g·cm−3 ZnCl2 solution as a density separation medium and were burned in a drop-tube furnace (DTF. The mineral matter in each of the light coal fractions was compared to that of the relevant raw coal. The DTF ash from light coal fractions was analysed using hydrochloric acid separation. The acid-soluble aluminium fractions of DTF ash samples were used to determine changes in the amorphous aluminosilicate products with increasing combustion temperature. The results show that the clay mineral contents in the mineral matter of both light coal fractions were higher than those in the respective raw coals. For the coal with a high ash melting point, clay minerals in the light coal fraction thermally transformed more dehydroxylation products compared with those in the raw coal, possibly contributing to solid-state reactions of ash particles. For the coal with a low ash melting point, clay minerals in the light coal fraction produced more easily-slagging material compared with those in the raw coal, playing an important role in the occurrence of slagging. Additionally, ferrous oxide often produces low-melting substances in coal ash. Due to the similarities of zinc oxide and ferrous oxide in silicate reactions, we also investigated the interactions of clay minerals in light coal fractions with zinc oxide introduced by a zinc chloride solution. The extraneous zinc oxide could react, to a small extent, with clay minerals in the coal during DTF combustion.

Determining Role of the Chain Mechanism in the Temperature Dependence of the Gas-Phase Rate of Combustion Reactions

Science.gov (United States)

Azatyan, V. V.; Bolod'yan, I. A.; Kopylov, N. P.; Kopylov, S. N.; Prokopenko, V. M.; Shebeko, Yu. N.

2018-05-01

It is shown that the strong dependence of the rate of gas-phase combustion reactions on temperature is determined by the high values of the reaction rate constants of free atoms and radicals. It is established that with a branched chain mechanism, a special role in the reaction rate temperature dependence is played by positive feedback between the concentrations of active intermediate species and the rate of their change. The role of the chemical mechanism in the temperature dependence of the process rate with and without inhibitors is considered.

In situ TEM observation of solid-gas reactions

International Nuclear Information System (INIS)

Kishita, K; Kamino, T; Watabe, A; Kuroda, K; Saka, H

2008-01-01

Under a gaseous atmosphere at high temperatures, almost all the materials (metal, catalysts, etc.) change their structures and properties. For the research and development of materials, it is of vital importance to clarify mechanisms of solid-gas and liquid-gas reactions. Recently an in situ TEM system combined with an environmental holder, which has a gas injection nozzle close to a specimen-heating element, has been developed. The gas injection nozzle permits gas to flow around the specimens sitting on the heating element made of a fine W filament. The newly developed in situ TEM has a differential pumping system; therefore, the pressure in the specimen chamber is maintained in the range of higher than 1 Pa, while the pressure in the electron gun chamber can be kept in the range of 10 -5 Pa. This system was applied to in situ observation of chemical reactions of metals with gases: Observation of oxidation and reduction under a gas pressure ranging from 10 -5 Pa to 1 Pa at high temperatures (room temperature to ∼1473 K) were successfully carried out on pure metal and rare metal catalysts at near-atomic resolution. This in situ environmental TEM system is promising for clarifying mechanisms of many solid-gas and liquid-gas reactions that take place at high temperatures under a gas atmosphere.

Fabrication of a Spherical Titanium Powder by Combined Combustion Synthesis and DC Plasma Treatment

Directory of Open Access Journals (Sweden)

Choi S.H.

2017-06-01

Full Text Available Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO2 with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4, the thermocouples registered temperatures between 1160°C and 1710°C · 3 mol of Mg gave the optimum results with combustion temperature (Tc and combustion velocity (Uc values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%. After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis.

Combustion of Metals in Reduced-Gravity and Extra Terrestrial Environments

Science.gov (United States)

Branch, M.C.; Abbud-Madrid, A.; Daily, J. W.

1999-01-01

The combustion of metals is a field with important practical applications in rocket propellants, high-temperature flames, and material synthesis. Also, the safe operation of metal containers in high-pressure oxygen systems and with cryogenic fuels and oxidizers remains an important concern in industry. The increasing use of metallic components in spacecraft and space structures has also raised concerns about their flammability properties and fire suppression mechanisms. In addition, recent efforts to embark on unmanned and manned planetary exploration, such as on Mars, have also renewed the interest in metal/carbon-dioxide combustion as an effective in situ resource utilization technology. In spite of these practical applications, the understanding of the combustion properties of metals remains far behind that of the most commonly used fuels such as hydrocarbons. The lack of understanding is due to the many problems unique to metal- oxidizer reactions such as: low-temperature surface oxidation prior to ignition, heterogeneous reactions, very high combustion temperatures, product condensation, high emissivity of products, and multi-phase interactions. Very few analytical models (all neglecting the influence of gravity) have been developed to predict the burning characteristics and the flame structure details. Several experimental studies attempting to validate these models have used small metal particles to recreate gravity-free conditions. The high emissivity of the flames, rapid reaction, and intermittent explosions experienced by these particles have made the gathering of any useful information on burning rates and flame structure very difficult. The use of a reduced gravity environment is needed to clarify some of the complex interactions among the phenomena described above. First, the elimination of the intrusive buoyant flows that plague all combustion phenomena is of paramount importance in metal reactions due to the much higher temperatures reached during

Influence of the Structure of a Solid-Fuel Mixture on the Thermal Efficiency of the Combustion Chamber of an Engine System

Science.gov (United States)

Futko, S. I.; Koznacheev, I. A.; Ermolaeva, E. M.

2014-11-01

On the basis of thermodynamic calculations, the features of the combustion of a solid-fuel mixture based on the glycidyl azide polymer were investigated, the thermal cycle of the combustion chamber of a model engine system was analyzed, and the efficiency of this chamber was determined for a wide range of pressures in it and different ratios between the components of the combustible mixture. It was established that, when the pressure in the combustion chamber of an engine system increases, two maxima arise successively on the dependence of the thermal efficiency of the chamber on the weight fractions of the components of the combustible mixture and that the first maximum shifts to the side of smaller concentrations of the glycidyl azide polymer with increase in the pressure in the chamber; the position of the second maximum is independent of this pressure, coincides with the minimum on the dependence of the rate of combustion of the mixture, and corresponds to the point of its structural phase transition at which the mole fractions of the carbon and oxygen atoms in the mixture are equal. The results obtained were interpreted on the basis of the Le-Chatelier principle.

Morphologic and structural characterization of the CoFe2O4 synthesized by combustion reaction

International Nuclear Information System (INIS)

Lima, M.S.; Sousa, J.-P.L.M.L.; Vieira, D.A.; Lira, H.L.; Costa, A.C.F.M.; Sasaki, J.M.

2009-01-01

CoFe 2 O 4 powders were synthesized by combustion reaction using glycine as fuel, aiming obtaining nanosized and monophase powders. Thus, different conditions of external heating during the synthesis were investigated. The powders were prepared according to the propellants and explosives theory, using glycine as fuel in the stoichiometric proportion (Φe = 1). During the synthesis the flame temperature and time were measured. The resulting powders were characterized by X-rays diffraction and scanning electronic microscopy (SEM). The results show that the condition in which the synthesis was realized it influences in the combustion flame temperature and time and contributes for the obtainment of powders with majority phase without secondary phases. Crystallite size varied of 33 to 50 nm. All powders presented morphology constituted by soft agglomerated formed by nanoparticles. (author). (author)

Study of ignition, combustion, and production of harmful substances upon burning solid organic fuel at a test bench with a vortex chamber

Science.gov (United States)

Burdukov, A. P.; Chernetskiy, M. Yu.; Dekterev, A. A.; Anufriev, I. S.; Strizhak, P. A.; Greben'kov, P. Yu.

2016-01-01

Results of investigation of furnace processes upon burning of pulverized fuel at a test bench with a power of 5 MW are presented. The test bench consists of two stages with tangential air and pulverized coal feed, and it is equipped by a vibrocentrifugal mill and a disintegrator. Such milling devices have an intensive mechanical impact on solid organic fuel, which, in a number of cases, increases the reactivity of ground material. The processes of ignition and stable combustion of a mixture of gas coal and sludge (wastes of concentration plant), as well as Ekibastus coal, ground in the disintegrator, were studied at the test bench. The results of experimental burning demonstrated that preliminary fuel grinding in the disintegrator provides autothermal combustion mode even for hardly inflammable organic fuels. Experimental combustion of biomass, wheat straw with different lignin content (18, 30, 60%) after grinding in the disintegrator, was performed at the test bench in order to determine the possibility of supporting stable autothermal burning. Stable biofuel combustion mode without lighting by highly reactive fuel was achieved in the experiments. The influence of the additive GTS-Powder (L.O.M. Leaders Co., Ltd., Republic of Korea) in the solid and liquid state on reducing sulfur oxide production upon burning Mugun coal was studied. The results of experimental combustion testify that, for an additive concentration from 1 to 15% of the total mass of the burned mixture, the maximum SO2 concentration reduction in ejected gases was not more than 18% with respect to the amount for the case of burning pure coal.

Numerical and experimental investigation of the effect of geometry on combustion characteristics of solid-fuel ramjet

Science.gov (United States)

Gong, Lunkun; Chen, Xiong; Musa, Omer; Yang, Haitao; Zhou, Changsheng

2017-12-01

Numerical and experimental investigation on the solid-fuel ramjet was carried out to study the effect of geometry on combustion characteristics. The two-dimensional axisymmetric program developed in the present study adopted finite rate chemistry and second-order moment turbulence-chemistry models, together with k-ω shear stress transport (SST) turbulence model. Experimental data were obtained by burning cylindrical polyethylene using a connected pipe facility. The simulation results show that a fuel-rich zone near the solid fuel surface and an air-rich zone in the core exist in the chamber, and the chemical reactions occur mainly in the interface of this two regions; The physical reasons for the effect of geometry on regression rate is the variation of turbulent viscosity due to the geometry change. Port-to-inlet diameter ratio is the main parameter influencing the turbulent viscosity, and a linear relationship between port-to-inlet diameter and regression rate were obtained. The air mass flow rate and air-fuel ratio are the main influencing factors on ramjet performances. Based on the simulation results, the correlations between geometry and air-fuel ratio were obtained, and the effect of geometry on ramjet performances was analyzed according to the correlation. Three-dimensional regression rate contour obtained experimentally indicates that the regression rate which shows axisymmetric distribution due to the symmetry structure increases sharply, followed by slow decrease in axial direction. The radiation heat transfer in recirculation zone cannot be ignored. Compared with the experimental results, the deviations of calculated average regression rate and characteristic velocity are about 5%. Concerning the effect of geometry on air-fuel ratio, the deviations between experimental and theoretical results are less than 10%.

Chemical Looping Combustion of Solid Fuels in a 10 kWth Unit Combustion de charge solide en boucle chimique dans une unité de 10 kWth

Directory of Open Access Journals (Sweden)

Berguerand N.

2011-02-01

Full Text Available The present study is based on previous results from batch experiments which were conducted in a 10 kWth chemical looping combustor for solid fuels using ilmenite, an iron titanium oxide, as the oxygen carrier with two solid fuels: a Mexican petroleum coke and a South African bituminous coal. These experiments involved testing at different fuel reactor temperatures, up to 1030°C, and different particle circulation rates between the air and fuel reactors. Previous results enabled modeling of the reactor system. In particular, it was possible to derive a correlation between measured operational data and actual circulation mass flow, as well as a model that describes the carbon capture efficiency as a function of the residence time and the char reactivity. Moreover, the kinetics of char conversion could be modeled and results showed good agreement with experimental values. The purpose of the present study was to complete these results by developing a model to predict the conversion of syngas with ilmenite in the fuel reactor. Here, kinetic data from investigations of ilmenite in TGA and batch fluidized bed reactors were used. Results were compared with the actual conversions during operation in this 10 kWth unit. Cette étude est basée sur des résultats antérieurs obtenus dans une unité de combustion de charges solides en boucle chimique d’une puissance de 10 kWth. Le transporteur d’oxygène utilisé est de l’ilménite, un minerai de fer et de titane, et les charges solides étudiées sont, d’une part, un coke de pétrole mexicain et, d’autre part, un charbon bitumineux sud africain. Les résultats expérimentaux ont été obtenus à des températures allant jusqu’à 1030°C avec différents débits de transporteur d’oxygène entre les réacteurs d’oxydation et de réduction. La modélisation de la combustion en boucle chimique de charges solides a déjà permis d’établir une corrélation entre le débit de circulation de

Extended lattice Boltzmann scheme for droplet combustion.

Science.gov (United States)

Ashna, Mostafa; Rahimian, Mohammad Hassan; Fakhari, Abbas

2017-05-01

The available lattice Boltzmann (LB) models for combustion or phase change are focused on either single-phase flow combustion or two-phase flow with evaporation assuming a constant density for both liquid and gas phases. To pave the way towards simulation of spray combustion, we propose a two-phase LB method for modeling combustion of liquid fuel droplets. We develop an LB scheme to model phase change and combustion by taking into account the density variation in the gas phase and accounting for the chemical reaction based on the Cahn-Hilliard free-energy approach. Evaporation of liquid fuel is modeled by adding a source term, which is due to the divergence of the velocity field being nontrivial, in the continuity equation. The low-Mach-number approximation in the governing Navier-Stokes and energy equations is used to incorporate source terms due to heat release from chemical reactions, density variation, and nonluminous radiative heat loss. Additionally, the conservation equation for chemical species is formulated by including a source term due to chemical reaction. To validate the model, we consider the combustion of n-heptane and n-butanol droplets in stagnant air using overall single-step reactions. The diameter history and flame standoff ratio obtained from the proposed LB method are found to be in good agreement with available numerical and experimental data. The present LB scheme is believed to be a promising approach for modeling spray combustion.

Experimental investigation of wood combustion in a fixed bed with hot air

Energy Technology Data Exchange (ETDEWEB)

Markovic, Miladin, E-mail: m.markovic@utwente.nl; Bramer, Eddy A.; Brem, Gerrit

2014-01-15

Highlights: • Upward combustion is a new combustion concept with ignition by hot primary air. • Upward combustion has three stages: short drying, rapid devolatilization and char combustion. • Variation of fuel moisture and inert content have little influence on the combustion. • Experimental comparison between conventional and upward combustion is presented. - Abstract: Waste combustion on a grate with energy recovery is an important pillar of municipal solid waste (MSW) management in the Netherlands. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Typically, the reaction zone starts at the top of the waste layer and propagates downwards, producing heat for drying and devolatilization of the fresh waste below it until the ignition front reaches the grate. The control of this process is mainly based on empiricism. MSW is a highly inhomogeneous fuel with continuous fluctuating moisture content, heating value and chemical composition. The resulting process fluctuations may cause process control difficulties, fouling and corrosion issues, extra maintenance, and unplanned stops. In the new concept the fuel layer is ignited by means of preheated air (T > 220 °C) from below without any external ignition source. As a result a combustion front will be formed close to the grate and will propagate upwards. That is why this approach is denoted by upward combustion. Experimental research has been carried out in a batch reactor with height of 4.55 m, an inner diameter of 200 mm and a fuel layer height up to 1 m. Due to a high quality two-layer insulation adiabatic conditions can be assumed. The primary air can be preheated up to 350 °C, and the secondary air is distributed via nozzles above the waste layer. During the experiments, temperatures along the height of the reactor, gas composition and total weight decrease are continuously monitored. The influence of

An alternative preparation method for ion exchanged catalysts: Solid state redox reaction

DEFF Research Database (Denmark)

Schneider, E.; Hagen, A.; Grunwaldt, J.-D.

2004-01-01

A new method for modifying zeolites with zinc is proposed. The solid state redox reaction between metallic zinc and ZSM-5 zeolites with different Si/Al ratios was investigated by temperature programmed hydrogen evolution (TPHE), X-ray absorption near edge structure (XANES) and diffuse reflectance...... infrared Fourier transform spectroscopy (DRIFTS). The evolution of hydrogen was detected at temperatures above 620 K. The source of hydrogen was the solid state redox reaction of the metal with protons of the support. The samples exhibit catalytic activity in ethane aromatization indicating that zinc...... should be located at the same sites as in catalysts prepared by conventional methods. Combination of XANES and catalytic activity point to zinc being mainly present in tetrahedral geometry under reaction conditions....

Influences of the molecular fuel structure on combustion reactions towards soot precursors in selected alkane and alkene flames.

Science.gov (United States)

Ruwe, Lena; Moshammer, Kai; Hansen, Nils; Kohse-Höinghaus, Katharina

2018-04-25

In this study, we experimentally investigate the high-temperature oxidation kinetics of n-pentane, 1-pentene and 2-methyl-2-butene (2M2B) in a combustion environment using flame-sampling molecular beam mass spectrometry. The selected C5 fuels are prototypes for linear and branched, saturated and unsaturated fuel components, featuring different C-C and C-H bond structures. It is shown that the formation tendency of species, such as polycyclic aromatic hydrocarbons (PAHs), yielded through mass growth reactions increases drastically in the sequence n-pentane fuel-dependent reaction sequences of the gas-phase combustion mechanism that provide explanations for the observed difference in the PAH formation tendency. First, we investigate the fuel-structure-dependent formation of small hydrocarbon species that are yielded as intermediate species during the fuel decomposition, because these species are at the origin of the subsequent mass growth reaction pathways. Second, we review typical PAH formation reactions inspecting repetitive growth sequences in dependence of the molecular fuel structure. Third, we discuss how differences in the intermediate species pool influence the formation reactions of key aromatic ring species that are important for the PAH growth process underlying soot formation. As a main result it was found that for the fuels featuring a C[double bond, length as m-dash]C double bond, the chemistry of their allylic fuel radicals and their decomposition products strongly influences the combination reactions to the initially formed aromatic ring species and as a consequence, the PAH formation tendency.

Torrefaction of empty fruit bunches under biomass combustion gas atmosphere.

Science.gov (United States)

Uemura, Yoshimitsu; Sellappah, Varsheta; Trinh, Thanh Hoai; Hassan, Suhaimi; Tanoue, Ken-Ichiro

2017-11-01

Torrefaction of oil palm empty fruit bunches (EFB) under combustion gas atmosphere was conducted in a batch reactor at 473, 523 and 573K in order to investigate the effect of real combustion gas on torrefaction behavior. The solid mass yield of torrefaction in combustion gas was smaller than that of torrefaction in nitrogen. This may be attributed to the decomposition enhancement effect by oxygen and carbon dioxide in combustion gas. Under combustion gas atmosphere, the solid yield for torrefaction of EFB became smaller as the temperature increased. The representative products of combustion gas torrefaction were carbon dioxide and carbon monoxide (gas phase) and water, phenol and acetic acid (liquid phase). By comparing torrefaction in combustion gas with torrefaction in nitrogen gas, it was found that combustion gas can be utilized as torrefaction gas to save energy and inert gas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of Combustion Tube for Gaseous, Liquid, and Solid Fuels to Study Flame Acceleration and DDT

Science.gov (United States)

Graziano, Tyler J.

An experimental combustion tube of 20 ft. in length and 10.25 in. in internal diameter was designed and fabricated in order to perform combustion tests to study deflagration rates, flame acceleration, and the possibility of DDT. The experiment was designed to allow gaseous, liquid, or solid fuels, or any combination of the three to produce a homogenous fuel/air mixture within the tube. Combustion tests were initiated with a hydrogen/oxygen torch igniter and the resulting flame behavior was measured with high frequency ion probes and pressure transducers. Tests were performed with a variety of gaseous and liquid fuels in an unobstructed tube with a closed ignition end and open muzzle. The flame performance with the gaseous fuels is loosely correlated with the expansion ratio, while there is a stronger correlation with the laminar flame speed. The strongest correlation to flame performance is the run-up distance scaling factor. This trend was not observed with the liquid fuels. The reason for this is likely due to incomplete evaporation of the liquid fuel droplets resulting in a partially unburned mixture, effectively altering the intended equivalence ratio. Results suggest that the simple theory for run-up distance and flame acceleration must be modified to more accurately predict the behavior of gaseous fuels. Also, it is likely that more complex spray combustion modeling is required to accurately predict the flame behavior for liquid fuels.

Combustion characteristics and air pollutant formation during oxy-fuel co-combustion of microalgae and lignite.

Science.gov (United States)

Gao, Yuan; Tahmasebi, Arash; Dou, Jinxiao; Yu, Jianglong

2016-05-01

Oxy-fuel combustion of solid fuels is seen as one of the key technologies for carbon capture to reduce greenhouse gas emissions. The combustion characteristics of lignite coal, Chlorella vulgaris microalgae, and their blends under O2/N2 and O2/CO2 conditions were studied using a Thermogravimetric Analyzer-Mass Spectroscopy (TG-MS). During co-combustion of blends, three distinct peaks were observed and were attributed to C. vulgaris volatiles combustion, combustion of lignite, and combustion of microalgae char. Activation energy during combustion was calculated using iso-conventional method. Increasing the microalgae content in the blend resulted in an increase in activation energy for the blends combustion. The emissions of S- and N-species during blend fuel combustion were also investigated. The addition of microalgae to lignite during air combustion resulted in lower CO2, CO, and NO2 yields but enhanced NO, COS, and SO2 formation. During oxy-fuel co-combustion, the addition of microalgae to lignite enhanced the formation of gaseous species. Copyright © 2016 Elsevier Ltd. All rights reserved.

NEDO project reports. High performance industrial furnace development project - High temperature air combustion

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-21

For the purpose of reducing energy consumption, a NEDO project 'Developmental research on high efficiency industrial furnaces' was carried out from FY 1993 to FY 1999 by The Japan Industrial Furnaces Manufacturers Association, and the paper outlined the details of the project. Industrial furnaces handled in this R and D can bring 30% reduction of the energy consumption and approximately 50% NOx reduction, and were given the 9th Nikkei global environmental technology prize. In the study of combustion phenomena of high temperature air combustion, the paper arranged characteristics of flame, the base of gaseous fuel flame, the base of liquid fuel flame, the base of solid fuel flame, etc. Concerning high temperature air combustion models for simulation, fluid dynamics and heat transfer models, and reaction and NOx models, etc. As to impacts of high temperature air combustion on performance of industrial furnaces, energy conservation, lowering of pollution, etc. In relation to a guide for the design of high efficiency industrial furnaces, flow charts, conceptual design, evaluation method for heat balance and efficiency using charts, combustion control system, applicability of high efficiency industrial furnaces, etc. (NEDO)

NEDO project reports. High performance industrial furnace development project - High temperature air combustion

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-21

For the purpose of reducing energy consumption, a NEDO project 'Developmental research on high efficiency industrial furnaces' was carried out from FY 1993 to FY 1999 by The Japan Industrial Furnaces Manufacturers Association, and the paper outlined the details of the project. Industrial furnaces handled in this R and D can bring 30% reduction of the energy consumption and approximately 50% NOx reduction, and were given the 9th Nikkei global environmental technology prize. In the study of combustion phenomena of high temperature air combustion, the paper arranged characteristics of flame, the base of gaseous fuel flame, the base of liquid fuel flame, the base of solid fuel flame, etc. Concerning high temperature air combustion models for simulation, fluid dynamics and heat transfer models, and reaction and NOx models, etc. As to impacts of high temperature air combustion on performance of industrial furnaces, energy conservation, lowering of pollution, etc. In relation to a guide for the design of high efficiency industrial furnaces, flow charts, conceptual design, evaluation method for heat balance and efficiency using charts, combustion control system, applicability of high efficiency industrial furnaces, etc. (NEDO)

Magneto-thermal and dielectric properties of biferroic YCrO3 prepared by combustion synthesis

International Nuclear Information System (INIS)

Duran, A.; Arevalo-Lopez, A.M.; Castillo-Martinez, E.; Garcia-Guaderrama, M.; Moran, E.; Cruz, M.P.; Fernandez, F.; Alario-Franco, M.A.

2010-01-01

Microstructural, magnetothermal and dielectric properties of YCrO 3 powders prepared by combustion and solid state methods have been studied by a combination of XRD, specific heat, magnetization and permittivity measurements. The TEM and XRD characterization confirm that the combustion powders are amorphous plate-like agglomerates of nano-sized crystalline particles. A more uniform grain size along with an increase of the relative density is observed by SEM in the sintered samples prepared by combustion route with respect to those produced by solid state reaction. Similar to the material obtained through solid state synthesis, the material prepared by the combustion method also shows spin canted antiferromagnetic ordering of Cr +3 (S=3/2) at ∼140 K, which is shown by magnetization as well as λ-type anomaly in the total specific heat. Furthermore, the magnetic contribution to the total specific heat reveals spin fluctuations above T N and a spin reorientation transition at about 60 K. Both YCrO 3 compounds show a diffuse phase transition at about 450 K, typical of a relaxor ferroelectric, which is characterized by a broad peak in the real part of the dielectric permittivity as a function of temperature, with the peak decreasing in magnitude and shifting to higher temperature as the frequency increases. The relaxor dipoles are due to the local non-centrosymmetric structure. Furthermore, the high loss tangent in a broad range of temperature as well as conductivity analysis indicates a hopping mechanism for the electronic conductivity as we believe it is a consequence of the outer d 3 -shell, which have detrimental effects on the polarization and the pooling process in the YCrO 3 bulk material. The more uniform particle size and higher density material synthesized through the combustion process leads to an improvement in the dielectric Properties. - Graphical abstract: Combustion method: An alternative route for synthesized a new family of multiferroics. Amorphous

Formation and destruction mechanisms of nitrogen oxides during coal combustion in circulating fluidized beds; Mecanismes de formation et de destruction des oxydes d`azote lors de la combustion du charbon en lit fluidise circulant

Energy Technology Data Exchange (ETDEWEB)

Borrel, G.; Lecuyer, I. [Universite du Haut-Rhin, 68 - Mulhouse (France)

1997-01-01

Formation and reduction of nitrogen oxides (NO and N{sub 2}O) during coal combustion in a circulating fluidized bed (CFBC) are very complicated and yet badly known. The aim of the present study was to better characterize these phenomena on a small-sized experimental unit (reactor diameter: 5 cm), with the possibility to re-inject the solids in the bottom of the furnace, as in a real industrial unit. This should allow then to develop a numerical set of chemical reactions involving the nitrogen oxides. The experimental results showed that coal ash plays a great role in reducing nitrogen oxides, the determining parameter being the quantity of unburnt carbon remaining in the ash. The study then detailed the interaction between nitrogen oxides and de-volatilized (char) according to the temperature, NO{sub x} concentration and the mass of solid. In the absence of oxygen small quantities of char can very significantly reduce NO as well as N{sub 2}O. It was possible to establish destruction kinetics on these particles, and orders of reaction could be determined versus the NO{sub x} concentration and the char particle mass (heterogeneous phase chemical reactions). Then, the coal pyrolysis study enabled to identify the products released during coal devolatilization and thermogravimetric analyses displayed several successive weight losses due CO, CO{sub 2} and CH{sub 4} releases, during a linear temperature increase. Lastly coal combustion was studied in the small pilot with variable experimental conditions. Using the previous experimental was studied in the small pilot with variable experimental conditions. Using the previous experimental results, a model was developed to calculate NO{sub x} concentrations during the coal combustion and validated. The NO and N{sub 2}O contents calculated are thoroughly correlated with the experimental data whatever the injection carbon/oxygen ratio is. (author) 96 refs.

A predictive model of natural gas mixture combustion in internal combustion engines

Directory of Open Access Journals (Sweden)

Henry Espinoza

2007-05-01

Full Text Available This study shows the development of a predictive natural gas mixture combustion model for conventional com-bustion (ignition engines. The model was based on resolving two areas; one having unburned combustion mixture and another having combustion products. Energy and matter conservation equations were solved for each crankshaft turn angle for each area. Nonlinear differential equations for each phase’s energy (considering compression, combustion and expansion were solved by applying the fourth-order Runge-Kutta method. The model also enabled studying different natural gas components’ composition and evaluating combustion in the presence of dry and humid air. Validation results are shown with experimental data, demonstrating the software’s precision and accuracy in the results so produced. The results showed cylinder pressure, unburned and burned mixture temperature, burned mass fraction and combustion reaction heat for the engine being modelled using a natural gas mixture.

IEA combustion agreement : a collaborative task on alternative fuels in combustion

International Nuclear Information System (INIS)

Larmi, M.

2009-01-01

The focus of the alternative fuels in combustion task of the International Energy Agency is on high efficiency engine combustion, furnace combustion, and combustion chemistry. The objectives of the task are to develop optimum combustion for dedicated fuels by fully utilizing the physical and chemical properties of synthetic and renewable fuels; a significant reduction in carbon dioxide, NOx and particulate matter emissions; determine the minimum emission levels for dedicated fuels; and meet future emission standards of engines without or with minimum after-treatment. This presentation discussed the alternative fuels task and addressed issues such as synthetic fuel properties and benefits. The anticipated future roadmap was presented along with a list of the synthetic and renewable engine fuels to be studied, such as neat oxygenates like alcohols and ethers, biogas/methane and gas combustion, fuel blends, dual fuel combustion, high cetane number diesel fuels like synthetic Fischer-Tropsch diesel fuel and hydrogenated vegetable oil, and low CN number fuels. Implementation examples were also discussed, such as fuel spray studies in optical spray bombs; combustion research in optical engines and combustion chambers; studies on reaction kinetics of combustion and emission formation; studies on fuel properties and ignition behaviour; combustion studies on research engines; combustion optimization; implementing the optimum combustion in research engines; and emission measurements. Overall milestone examples and the overall schedule of participating countries were also presented. figs.

Combustion synthesis of inorganic materials; Muki zairyo no nensho gose

Energy Technology Data Exchange (ETDEWEB)

Oyanagi, M. [Ryukoku University, Kyoto (Japan)

1999-11-01

Combustion synthesis of porous titan carbide is outlined. In combustion synthesis, exothermic chain reaction, which is induced by igniting at one point of the simple substance mixture, propagates the combustion wave, and the compound is synthesized, which can be sintered by it. By this method, to this day intermetallic compounds, ceramics and high melting point composite materials have been synthesized, and synthetics can be made compact by adding pressure during or just after the reaction. Recently, applying the induction heating jointly, preheating before the reaction and heat treatment after the reaction can be controlled, accordingly, many high melting point inorganic compounds and composite materials can be made by combustion synthesis under pressure. (NEDO)

Combustion/particle sizing experiments at the Naval Postgraduate School Combustion Research Laboratory

Science.gov (United States)

Powers, John; Netzer, David

1987-01-01

Particle behavior in combustion processes is an active research area at NPS. Currently, four research efforts are being conducted: (1) There is a long standing need to better understand the soot production and combustion processes in gas turbine combustors, both from a concern for improved engine life and to minimize exhaust particulates. Soot emissions are strongly effected by fuel composition and additives; (2) A more recent need for particle sizing/behavior measurements is in the combustor of a solid fuel ramjet which uses a metallized fuel. High speed motion pictures are being used to study rather large burning particles; (3) In solid propellant rocket motors, metals are used to improve specific impulse and/or to provide damping for combustion pressure oscillations. Particle sizing experiments are being conducted using diode arrays to measure the light intensity as a function of scattering angle; (4) Once a good quality hologram is attained, a need exists for obtaining the particle distributions from hologram in a short period of time. A Quantimet 720 Image Analyzer is being used to reconstruct images.

Stochastic disturbances and dynamics of thermal processes. With application to municipal solid waste combustion

Energy Technology Data Exchange (ETDEWEB)

Van Kessel, L.B.M.

2003-06-11

The main topic of this thesis is the research into the disturbances and dynamics of the Municipal and Solid Waste Combustion (MSWC) process. As already said, the MSWC process suffers from large disturbances in the calorific value. At the start of this research it was obvious that for a good process analysis of the dynamics more information about the disturbances would be necessary. Therefore, a new on-line calorific value sensor was developed, which is described in chapter 2. The new on-line calorific value sensor makes it possible to monitor on-line important process variables like the calorific value and the water content of the fuel. The sensor is used to collect data from four different MSWC plants. Results from these MSWC plants will be presented. A comparison with traditional off-line methods and possible applications will be discussed as well. After revealing the main disturbances of the process the study of the process dynamics can be performed. A mathematical dynamic model of the process is very useful for studying the dynamics of a process. Therefore, in chapter 3 a general model for the dynamics of thermal processes is derived. This general model is applied to MSWC, which yields a completely new model description of the MSWC process. However, a model has to be validated with practical data. Unfortunately, MSWC plants suffer from large disturbances, which makes a good validation complicated. As no good information for the validation of processes like MSWC was available in literature, new validation techniques have been applied to MSWC plants. The validation results will be presented. The results from the validation experiments will show that the combustion process in practice can become completely different when different primary air temperatures are used. Two situations with different primary air temperatures will be discussed in detail including the application of the derived dynamic model to explain the differences. When the disturbances are measured

Use of combustible wastes as fuel

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.; Salamov, A.A.

1983-01-01

Achievements of science and technology in creating and using units for combustion of wastes with recovery of heat of the escaping gases has been systematized and generalized. Scales and outlooks are examined for the use of general, industrial and agricultural waste as fuel, composition of the waste, questions of planning and operating units for combustion of solid refuse, settling of waste water and industrial and agricultural waste. Questions are covered for preparing them for combustion use in special units with recovery of heat and at ES, aspects of environmental protection during combustion of waste, cost indicators of the employed methods of recovering the combustible waste.

Irradiated ignition over solid materials in reduce pressure environment: Fire safety issue in man-made enclosure system

Science.gov (United States)

Nakamura, N.; Aoki, A.

Effects of ambient pressure and oxygen yield on irradiated ignition characteristics over solid combustibles have been studied experimentally Aim of the present study is to elucidate the flammability and chance of fire in depressurized enclosure system and give ideas for the fire safety and fire fighting strategies in such environment Thin cellulosic paper is considered as the solid combustible since cellulose is one of major organic compounds and flammables in the nature Applied atmosphere consists of inert gas either CO2 or N2 and oxygen and various mixture ratios are of concerned Total ambient pressure level is varied from 0 1MPa standard atmospheric pressure to 0 02MPa Ignition is initiated by external thermal flux exposed into the solid surface as a model of unexpected thermal input to initiate the localized fire Thermal degradation of the solid induces combustible gaseous products e g CO H2 or other low class of HCs and the gas mixes with ambient oxygen to form the combustible mixture over the solid Heat transfer from the hot irradiated surface into the mixture accelerates the local exothermic reaction in the gas phase and finally thermal runaway ignition is achieved Ignition event is recorded by high-speed digital video camera to analyze the ignition characteristics Flammable map in partial pressure of oxygen Pox and total ambient pressure Pt plane is made to reveal the fire hazard in depressurized environment Results show that wider flammable range is obtained depending on the imposed ambient

Reactions homogenes en phase gazeuse dans les lits fluidises

Science.gov (United States)

Laviolette, Jean-Philippe

measurements of solids flux, chemical composition, temperature and pressure. Autoignition was only recorded within 0.06 m of the bed surface at temperatures greater than 833 K. Propane conversion predicted by six different microkinetic mechanistic models were compared to the experimental measurements: all six models underestimated the reaction rate above the bed surface. However, accounting for the production of H2O2 during in-bed combustion significantly increased the calculated reaction rates and resulted in a better agreement between predicted and measured propane conversion. In the third part of this work, a novel spectroscopic method was developed to measure quantitatively and simultaneously solids volume fraction (1-epsilon) and gaseous species composition (Yi) in a gas/solid system. The method was comprised of an FT-IR coupled to a fibre-optic probe that could perform real-time and in-situ measurements of absorbance. The effect of (1-epsilon) and Yi on the absorbance spectra were additive and could be independently calibrated. Experiments were conducted with alkane/nitrogen mixtures and two types of particles: sand and FCC. Fuel mole fractions and (1-epsilon) were varied between 1.8 - 10.1 mol% and 0 - 0.45, respectively. The relative errors for Yi time-averaged measurements were below 6% and the error increased significantly with decreasing beam intensity. A proof of concept for a novel application in fluidized beds was also completed: the fibre-optic probe was used to measure the molar fraction of a tracer gas inside the emulsion and bubble phases during gas tracer experiments. (Abstract shortened by UMI.)

Neutrophil Leukocyte: Combustive Microbicidal Action and Chemiluminescence

Directory of Open Access Journals (Sweden)

Robert C. Allen

2015-01-01

Full Text Available Neutrophil leukocytes protect against a varied and complex array of microbes by providing microbicidal action that is simple, potent, and focused. Neutrophils provide such action via redox reactions that change the frontier orbitals of oxygen (O2 facilitating combustion. The spin conservation rules define the symmetry barrier that prevents direct reaction of diradical O2 with nonradical molecules, explaining why combustion is not spontaneous. In burning, the spin barrier is overcome when energy causes homolytic bond cleavage producing radicals capable of reacting with diradical O2 to yield oxygenated radical products that further participate in reactive propagation. Neutrophil mediated combustion is by a different pathway. Changing the spin quantum state of O2 removes the symmetry restriction to reaction. Electronically excited singlet molecular oxygen (O2*1 is a potent electrophilic reactant with a finite lifetime that restricts its radius of reactivity and focuses combustive action on the target microbe. The resulting exergonic dioxygenation reactions produce electronically excited carbonyls that relax by light emission, that is, chemiluminescence. This overview of neutrophil combustive microbicidal action takes the perspectives of spin conservation and bosonic-fermionic frontier orbital considerations. The necessary principles of particle physics and quantum mechanics are developed and integrated into a fundamental explanation of neutrophil microbicidal metabolism.

MULTIFUNCTIONAL (NOx/CO/O2) SOLID-STATE SENSORS FOR COAL COMBUSTION CONTROL

Energy Technology Data Exchange (ETDEWEB)

Eric D. Wachsman

2005-05-29

We have made great progress in both developing solid state sensors for coal combustion control and understanding the mechanism by which they operate. We have fabricated and tested numerous sensors and identified the role electrode microstructure plays in sensor response. We have developed both p-type (La{sub 2}CuO{sub 4}) and n-type (WO{sub 3}) semiconducting NO{sub x} sensing electrodes. We have demonstrated their respective sensing behavior (sensitivities and cross-sensitivities), related this behavior to their gas adsorption/desorption behavior and catalytic activity, and in so doing verified that our proposed Differential Electrode Equilibria is a more comprehensive sensing mechanism. These investigations and their results are summarized below. The composition and microstructure of the sensing electrode is the key parameters that influence the sensing performance. We investigated the effect of electrode microstructure on the NO{sub x} sensitivity and response time using a La{sub 2}CuO{sub 4}-based potentiometric sensor. Temperature dependence, cross-sensitivity and selectivities of a La{sub 2}CuO{sub 4}- and WO{sub 3}-based potentiometric NO{sub x} sensor were investigated both in N{sub 2} and in a simulated exhaust gas. We performed temperature programmed reaction (TPR) and desorption (TPD) experiments to determine the reaction and adsorption characteristics of O{sub 2}, NO{sub x}, CO, CO{sub 2}, and their mixtures on the electrodes, and related the results to sensor performance. In order to optimize the sensor electrode microstructure, powders were prepared using four different powder synthesis routes, resulting in different particle size distributions and BET surface areas. Different sintering conditions were also applied. The microstructure of electrodes, synthesized with the same composition, has a dramatic effect on both sensitivity and response time of potentiometric NO sensors, showing that large surface areas generate a porous morphology with smaller

Pre-Combustion Capture of CO2 in IGCC Plants

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-12-15

Pre-combustion capture involves reacting a fuel with oxygen or air and/or steam to give mainly a 'synthesis gas (syngas)' or 'fuel gas' composed of carbon monoxide and hydrogen. The carbon monoxide is reacted with steam in a catalytic reactor, called a shift converter, to produce CO2 and more hydrogen. CO2 is then separated, usually by a physical or chemical absorption process, resulting in a hydrogen-rich fuel which can be used in many applications, such as boilers, furnaces, gas turbines, engines and fuel cells. Pre-combustion capture is suitable for use in integrated gasification combined cycle (IGCC) plants especially since the CO2 partial pressures in the fuel gas are higher than in the flue gas. After the introduction there follows a short discussion of the water-gas shift (WGS) reaction. This is followed by chapters on the means of CO2 capture by physical and chemical solvents, solid sorbents, and membranes. The results and conclusions of techno-economic studies are introduced followed by a look at some of the pilot and demonstration plants relevant to pre-combustion capture in IGCC plants.

Modeling and simulation of combustion chamber and propellant dynamics and issues in active control of combustion instabilities

Science.gov (United States)

Isella, Giorgio Carlo

A method for a comprehensive approach to analysis of the dynamics of an actively controlled combustion chamber, with detailed analysis of the combustion models for the case of a solid rocket propellant, is presented here. The objective is to model the system as interconnected blocks describing the dynamics of the chamber, combustion and control. The analytical framework for the analysis of the dynamics of a combustion chamber is based on spatial averaging, as introduced by Culick. Combustion dynamics are analyzed for the case of a solid propellant. Quasi-steady theory is extended to include the dynamics of the gas-phase and also of a surface layer. The models are constructed so that they produce a combustion response function for the solid propellant that can be immediately introduced in the our analytical framework. The principal objective mechanisms responsible for the large sensitivity, observed experimentally, of propellant response to small variations. We show that velocity coupling, and not pressure coupling, has the potential to be the mechanism responsible for that high sensitivity. We also discuss the effect of particulate modeling on the global dynamics of the chamber and revisit the interpretation of the intrinsic stability limit for burning of solid propellants. Active control is also considered. Particular attention is devoted to the effect of time delay (between sensing and actuation); several methods to compensate for it are discussed, with numerical examples based on the approximate analysis produced by our framework. Experimental results are presented for the case of a Dump Combustor. The combustor exhibits an unstable burning mode, defined through the measurement of the pressure trace and shadowgraph imaging. The transition between stable and unstable modes of operation is characterized by the presence of hysteresis, also observed in other experimental works, and hence not a special characteristic of this combustor. Control is introduced in the

Numerical Simulation of In Situ Combustion of Oil Shale

Directory of Open Access Journals (Sweden)

Huan Zheng

2017-01-01

Full Text Available This paper analyzes the process of in situ combustion of oil shale, taking into account the transport and chemical reaction of various components in porous reservoirs. The physical model is presented, including the mass and energy conservation equations and Darcy’s law. The oxidation reactions of oil shale combustion are expressed by adding source terms in the conservation equations. The reaction rate of oxidation satisfies the Arrhenius law. A numerical method is established for calculating in situ combustion, which is simulated numerically, and the results are compared with the available experiment. The profiles of temperature and volume fraction of a few components are presented. The temperature contours show the temperature variation in the combustion tube. It is found that as combustion reaction occurs in the tube, the concentration of oxygen decreases rapidly, while the concentration of carbon dioxide and carbon monoxide increases contrarily. Besides, the combustion front velocity is consistent with the experimental value. Effects of gas injection rate, permeability of the reservoir, initial oil content, and injected oxygen content on the ISC process were investigated in this study. Varying gas injection rate and oxygen content is important in the field test of ISC.

A method for determining the completeness of fuel combustion

Energy Technology Data Exchange (ETDEWEB)

Tavger, M.D.; Chepkin, V.M.; Gruzdev, V.N.; Talantov, A.V.

1982-01-01

The current of conductivity (ionization) of gaseous combustion products, which forms with feeding of electric voltage to a special probe, is proposed for determining the completeness of fuel combustion. Here, the charged particles are formed from substances which form in the intermediate stages of the combustion reaction. The volume of charged particles is proportional to the volume of the intermediate substances, whose presence attests to the incompleteness of the combustion reaction. The fullness of fuel combustion is determined from a formula which includes the stoichiometric coefficient, a gas constant, the energy of activation, the characteristics of the chemical activity of the intermediate substances, the coefficient of air excess, the temperature of the combustion products and the conductivity current.

Numerical simulations of turbulent jet ignition and combustion

Science.gov (United States)

Validi, Abdoulahad; Irannejad, Abolfazl; Jaberi, Farhad

2013-11-01

The ignition and combustion of a homogeneous lean hydrogen-air mixture by a turbulent jet flow of hot combustion products injected into a colder gas mixture are studied by a high fidelity numerical model. Turbulent jet ignition can be considered as an efficient method for starting and controlling the reaction in homogeneously charged combustion systems used in advanced internal combustion and gas turbine engines. In this work, we study in details the physics of turbulent jet ignition in a fundamental flow configuration. The flow and combustion are modeled with the hybrid large eddy simulation/filtered mass density function (LES/FMDF) approach, in which the filtered form the compressible Navier-Stokes equations are solved with a high-order finite difference scheme for the turbulent velocity and the FMDF transport equations are solved with a Lagrangian stochastic method to obtain the scalar (temperature and species mass fractions) field. The hydrogen oxidation is described by a detailed reaction mechanism with 37 elementary reactions and 9 species.

Gradual combustion - method for nitrogen oxide suppression during brown coal combustion

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.P.; Verzakov, V.N.; Lobov, T.V.

1990-10-01

Discusses combustion of brown coal in BKZ-500-140-1 boilers and factors that influence emission of nitrogen oxides. Temperature distribution in the furnace was evaluated. Effects of burner position, burner number and burner type as well as air excess ratio on chemical reactions during brown coal combustion, formation of nitrogen oxides and their emission were comparatively evaluated. Analyses showed that by optimum arrangement of burners and selecting the optimum air excess ratio a part of nitrogen oxides formed during the initial phase of combustion was reduced to molecular nitrogen in the second phase. On the basis of evaluations the following recommendations for furnace design are made: use of straight-flow burners characterized by a reduced mixing ratio with secondary air, parallel arrangement of burners which guarantees mixing of the combustion products from the burners with stable and unstable combustion (products of incomplete coal combustion), reducing the air excess ratio to below 1.0. 5 refs.

Effect of flue gas recirculation during oxy-fuel combustion in a rotary cement kiln

International Nuclear Information System (INIS)

Granados, David A.; Chejne, Farid; Mejía, Juan M.; Gómez, Carlos A.; Berrío, Ariel; Jurado, William J.

2014-01-01

The effect of Flue Gas Recirculation (FGR) during Oxy-Fuel Combustion in a Rotary Cement Kiln was analyzed by using a CFD model applied to coal combustion process. The CFD model is based on 3D-balance equations for mass, species, energy and momentum. Turbulence and radiation model coupled to a chemical kinetic mechanism for pyrolysis processes, gas–solid and gas–gas reactions was included to predicts species and flame temperature distribution, as well as convective and radiation energy fluxes. The model was used to study coal combustion with air and with oxygen for FGR between 30 and 85% as controller parameter for temperature in the process. Flame length effect and heat transfer by convection and radiation to the clinkering process for several recirculation ratios was studied. Theoretical studies predicted a located increase of energy flux and a reduction in flame length with respect to the traditional system which is based on air combustion. The impact of FGR on the oxy-fuel combustion process and different energy scenarios in cement kilns to increase energy efficiency and clinker production were studied and evaluated. Simulation results were in close agreement with experimental data, where the maximum deviation was 7%

Emission factors of carbonaceous particulate matter and polycyclic aromatic hydrocarbons from residential solid fuel combustions

Energy Technology Data Exchange (ETDEWEB)

Shen, Guofeng [Jiangsu Academy of Environmental Science, Nanjing (China). Inst. of Atmospheric Sciences

2014-07-01

Emission inventory is basic for the understanding of environmental behaviors and potential effects of compounds, however, current inventories are often associated with relatively high uncertainties. One important reason is the lack of emission factors, especially for the residential solid fuel combustion in developing countries. In the present study, emission factors of a group of pollutants including particulate matter, organic carbon, elemental carbon (sometimes known as black carbon) and polycyclic aromatic hydrocarbons were measured for a variety of residential solid fuels including coal, crop straw, wood, and biomass pellets in rural China. The study provided a large number of emission factors that can be further used in emission estimation. Composition profiles and isomer ratios were investigated and compared so as to be used in source apportionment. In addition, the present study identified and quantified the influence of factors like fuel moisture, volatile matter on emission performance.

Morphological and structural characterization of the Zn0,9Mn0,1O powder synthesized by combustion reaction and Pechini

International Nuclear Information System (INIS)

Ribeiro, M.A.; Torquato, R.; Simoes, A.N.; Costa, A.C.F.M.; Gama, L.; Kiminami, R.H.G.A.

2009-01-01

Zinc oxide, due to the piezoelectric and electro-optical characteristics, is used in application such as, chemical sensor, varistor, transparent conductive thin film and DMS. The aim of this work is to evaluate and compare structural and morphological characteristics of nanometric powders of Zn 0,9 Mn 0,1 O prepared by chemical synthesis of combustion reaction and Pechini method. The powders were characterized by XRD, SEM and BET. The XRD data shown to both studied method the presence of ZnO phase with hexagonal structure and without second phase. The powder prepared by combustion reaction presented 9% of reduction in crystallinity and 42% of increase in surface area in comparison with the powder prepared by Pechini method. The morphological analysis of the powder showed that both method produce powders with soft agglomerates constituted by nano size particles. (author)

Investigation of reactions and species dominating low temperature combustion - Final report

Energy Technology Data Exchange (ETDEWEB)

Gerber, T.; Radi, P.; Knopp, G.; Tulej, M.

2007-07-01

This final report for the Swiss Federal Office of Energy (SFOE), reports on work done in 2007 at the Paul Scherrer Institute PSI in Switzerland on the quantitative description of ignition. processes and the influence of peroxy radicals that determine ignition and speciation of the intermediates initially present and, thereby, the progress of subsequent reactions. The authors note that for the preparation of peroxy radicals, a dedicated molecular beam apparatus has been built by the PSI's 'Molecular Dynamics' group. A novel radical source is operational. In many cases, specific radicals can be prepared with high selectivity. A description of flame chemistry is being worked on that can reliably predict the speciation of intermediate products during ignition. Laser-based measurement techniques are being applied at PSI to measure the static and dynamic properties of alkyl peroxy radicals in order to accurately describe their reaction behaviour in combustion processes. A dedicated synchrotron beam line is installed at the Swiss Light Source (SLS) that extends the available range of spectroscopic measurements into the VUV (vacuum-ultraviolet) wavelength domain. The results obtained are presented and discussed.

Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics.

Science.gov (United States)

Jung, Choong-Hwan; Kim, Yeon-Ku; Han, Young-Min; Lee, Sang-Jin

2016-02-01

A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

Mathematical Modeling in Combustion Science

CERN Document Server

Takeno, Tadao

1988-01-01

An important new area of current research in combustion science is reviewed in the contributions to this volume. The complicated phenomena of combustion, such as chemical reactions, heat and mass transfer, and gaseous flows, have so far been studied predominantly by experiment and by phenomenological approaches. But asymptotic analysis and other recent developments are rapidly changing this situation. The contributions in this volume are devoted to mathematical modeling in three areas: high Mach number combustion, complex chemistry and physics, and flame modeling in small scale turbulent flow combustion.

Combustion synthesis by reaction and characterization of nano ferrites: study of fuel aniline, citric and its mixture

International Nuclear Information System (INIS)

Silva, M.C. da; Coutinho, J.P.; Costa, A.C.F.M.; Kiminami, R.H.G.A.; Freitas, N.L. de

2012-01-01

The present study aims to evaluate the influence of aniline and citric acid used alone and combined in a ratio of 50% each in the characterization of NiZn ferrite synthesized by combustion reaction method in a muffle furnace. Measurements were made of temperature and reaction time. The nano-powders were characterized by XRD, EDX, textural analysis and SEM. The highest temperature was achieved by the reaction using the mixture of fuel and increased reaction time using citric acid. The nano ferrites using different fuels, and the mixture changed phases, the crystallite size and decreased surface area of the samples with aniline, citric acid and a mixture of both, respectively. The powder morphology ranged from presenting the formation of irregular blocks for the use of citric agglomerated in the form of skeins with aniline and a mixture to agglomerate larger particles. (author)

Construction of combustion models for rapeseed methyl ester bio-diesel fuel for internal combustion engine applications.

Science.gov (United States)

Golovitchev, Valeri I; Yang, Junfeng

2009-01-01

Bio-diesel fuels are non-petroleum-based diesel fuels consisting of long chain alkyl esters produced by the transesterification of vegetable oils, that are intended for use (neat or blended with conventional fuels) in unmodified diesel engines. There have been few reports of studies proposing theoretical models for bio-diesel combustion simulations. In this study, we developed combustion models based on ones developed previously. We compiled the liquid fuel properties, and the existing detailed mechanism of methyl butanoate ester (MB, C(5)H(10)O(2)) oxidation was supplemented by sub-mechanisms for two proposed fuel constituent components, C(7)H(16) and C(7)H(8)O (and then, by mp2d, C(4)H(6)O(2) and propyne, C(3)H(4)) to represent the combustion model for rapeseed methyl ester described by the chemical formula, C(19)H(34)O(2) (or C(19)H(36)O(2)). The main fuel vapor thermal properties were taken as those of methyl palmitate C(19)H(36)O(2) in the NASA polynomial form of the Burcat database. The special global reaction was introduced to "crack" the main fuel into its constituent components. This general reaction included 309 species and 1472 reactions, including soot and NO(x) formation processes. The detailed combustion mechanism was validated using shock-tube ignition-delay data under diesel engine conditions. For constant volume and diesel engine (Volvo D12C) combustion modeling, this mechanism could be reduced to 88 species participating in 363 reactions.

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

Research in Supercritical Fuel Properties and Combustion Modeling

Science.gov (United States)

2015-09-18

identified reactions needing further study and C-2 and C-3 species to add to the mechanism . 15. SUBJECT TERMS Supercritical fluids , Brillouin scattering...kinetics mechanism for combustion of hydrocarbon fuels containing up to 2 carbon atoms, including uncertainties. • We identified key reactions and...safety. The chemical mechanisms for combustion of all of these fuels share the same set of elementary reactions of smaller-fragment hydrocarbons , and

Kinetics of the high-temperature combustion reactions of dibutylether using composite computational methods

KAUST Repository

Rachidi, Mariam El

2015-01-01

This paper investigates the high-temperature combustion kinetics of n-dibutyl ether (n-DBE), including unimolecular decomposition, H-abstraction by H, H-migration, and C{single bond}C/C{single bond}O β-scission reactions of the DBE radicals. The energetics of H-abstraction by OH radicals is also studied. All rates are determined computationally using the CBS-QB3 and G4 composite methods in conjunction with conventional transition state theory. The B3LYP/6-311++G(2df,2pd) method is used to optimize the geometries and calculate the frequencies of all reactive species and transition states for use in ChemRate. Some of the rates calculated in this study vary markedly from those obtained for similar reactions of alcohols or alkanes, particularly those pertaining to unimolecular decomposition and β-scission at the α-β C{single bond}C bond. These variations show that analogies to alkanes and alcohols are, in some cases, inappropriate means of estimating the reaction rates of ethers. This emphasizes the need to establish valid rates through computation or experimentation. Such studies are especially important given that ethers exhibit promising biofuel and fuel additive characteristics. © 2014.

Biofuels combustion.

Science.gov (United States)

Westbrook, Charles K

2013-01-01

This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly.

Sulfur Chemistry in Combustion I

DEFF Research Database (Denmark)

Johnsson, Jan Erik; Glarborg, Peter

2000-01-01

of the sulphur compounds in fossil fuels and the possibilities to remove them will be given. Then the combustion of sulphur species and their influence on the combustion chemistry and especially on the CO oxidation and the NOx formation will be described. Finally the in-situ removal of sulphur in the combustion...... process by reaction between SO2 and calcium containing sorbents and the influence on the NOx chemistry will be treated....

Analytical solutions for the temperature field in a 2D incompressible inviscid flow through a channel with walls of solid fuel

Directory of Open Access Journals (Sweden)

Sorin BERBENTE

2011-12-01

Full Text Available A gas (oxidizer flows between two parallel walls of solid fuel. A combustion is initiated: the solid fuel is vaporized and a diffusive flame occurs. The hot combustion products are submitted both to thermal diffusion and convection. Analytical solutions can be obtained both for the velocity and temperature distributions by considering an equivalent mean temperature where the density and the thermal conductivity are evaluated. The main effects of heat transfer are due to heat convection at the flame. Because the detailed mechanism of the diffusion flame is not introduced the reference chemical reaction is the combustion of premixed fuel with oxidizer in excess. In exchange the analytical solution is used to define an ideal quasi-uniform combustion that could be realized by an n adequate control. The given analytical closed solutions prove themselves flexible enough to adjust the main data of some existing experiments and to suggest new approaches to the problem.

Systems and methods of storing combustion waste products

Science.gov (United States)

Chen, Shen-En; Wang, Peng; Miao, Xiexing; Feng, Qiyan; Zhu, Qianlin

2016-04-12

In one aspect, methods of storing one or more combustion waste products are described herein. Combustion waste products stored by a method described herein can include solid combustion waste products such as coal ash and/or gaseous combustion products such as carbon dioxide. In some embodiments, a method of storing carbon dioxide comprises providing a carbon dioxide storage medium comprising porous concrete having a macroporous and microporous pore structure and flowing carbon dioxide captured from a combustion flue gas source into the pore structure of the porous concrete.

Emissions from residential combustion of different solid fuels. Roekgasemissioner vid anvaendning av olika fasta braenslen i smaaskaliga system

Energy Technology Data Exchange (ETDEWEB)

Rudling, L

1983-01-01

The emission from different types of solid fuels during combustion in residential furnaces and stoves has been investigated. The following fules were investigated: wood pellets, peat-bark pellets, wood chips, wood logs,wood-briquets, peat briquets, lignite briquets, fuel oil. Three different 20-25 kW boilers were used and one stove and one fire place. The flue gases were analysed for carbon dioxide, carbon monoxide, nitrogen oxides, hydrocarbons, particulates, tar and fluoranthen.

Comparison of different chemical kinetic mechanisms of methane combustion in an internal combustion engine configuration

OpenAIRE

Ennetta Ridha; Hamdi Mohamed; Said Rachid

2008-01-01

Three chemical kinetic mechanisms of methane combustion were tested and compared using the internal combustion engine model of Chemkin 4.02 [1]: one-step global reaction mechanism, four-step mechanism, and the standard detailed scheme GRIMECH 3.0. This study shows good concordances, especially between the four-step and the detailed mechanisms in the prediction of temperature and main species profiles. But reduced schemes were incapables to predict pollutant emissions in an internal combustion...

Co-combustion of Fossil Fuels and Waste

DEFF Research Database (Denmark)

Wu, Hao

The Ph.D. thesis deals with the alternative and high efficiency methods of using waste-derived fuels in heat and power production. The focus is on the following subjects: 1) co-combustion of coal and solid recovered fuel (SRF) under pulverized fuel combustion conditions; 2) dust-firing of straw...

Shock tube study of the reactions of the hydroxyl radical with combustion species and pollutants. Final report

Energy Technology Data Exchange (ETDEWEB)

Cohen, N.; Koffend, J.B.

1998-02-01

Shock heating t-butyl hydroperoxide behind a reflected shock wave has proved to be as a convenient source of hydroxyl radicals at temperatures near 1000 K. We applied this technique to the measurement of reaction rate coefficients of OH with several species of interest in combustion chemistry, and developed a thermochemical kinetics/transition state theory (TK-TST) model for predicting the temperature dependence of OH rate coefficients.

Model Research of Gas Emissions From Lignite and Biomass Co-Combustion in a Large Scale CFB Boiler

Directory of Open Access Journals (Sweden)

Krzywański Jarosław

2014-06-01

Full Text Available The paper is focused on the idea of a combustion modelling of a large-scale circulating fluidised bed boiler (CFB during coal and biomass co-combustion. Numerical computation results for three solid biomass fuels co-combustion with lignite are presented in the paper. The results of the calculation showed that in previously established kinetics equations for coal combustion, some reactions had to be modified as the combustion conditions changed with the fuel blend composition. Obtained CO2, CO, SO2 and NOx emissions are located in borders of ± 20% in the relationship to the experimental data. Experimental data was obtained for forest biomass, sunflower husk, willow and lignite cocombustion tests carried out on the atmospheric 261 MWe COMPACT CFB boiler operated in PGE Turow Power Station in Poland. The energy fraction of biomass in fuel blend was: 7%wt, 10%wt and 15%wt. The measured emissions of CO, SO2 and NOx (i.e. NO + NO2 were also shown in the paper. For all types of biomass added to the fuel blends the emission of the gaseous pollutants was lower than that for coal combustion.

Combustion of Sewage Sludge as Alternative Fuel for Cement Industry

Institute of Scientific and Technical Information of China (English)

LI Fuzhou; ZHANG Wei

2011-01-01

The combustion of sewage sludge and coal was studied by thermogravimetric analysis.Both differential scanning calorimetric analysis and derivative thermogravimetric profiles showed differences between combustion of sewage sludge and coal, and non-isothermal kinetics analysis method was applied to evaluate the combustion process. Based on Coats-Redfem integral method, some reaction models were tested,the mechanism and kinetics of the combustion reaction were discussed. The results show that the combustion of sewage sludge is mainly in the Iow temperature stage, meanwhile the ignition temperature and Arrhenius activation energy are lower than that of coal. The combustion of sewage sludge has the advantage over coal in some aspects, thus sewage sludge can partly replace coal used as cement industry fuel.

Integration of solid oxide fuel cell (SOFC) and chemical looping combustion (CLC) for ultra-high efficiency power generation and CO2 production

NARCIS (Netherlands)

Spallina, Vincenzo; Nocerino, Pasquale; Romano, Matteo C.; van Sint Annaland, Martin; Campanari, Stefano; Gallucci, Fausto

2018-01-01

This work presents a thermodynamic analysis of the integration of solid oxide fuel cells (SOFCs) with chemical looping combustion (CLC) in natural gas power plants. The fundamental idea of the proposed process integration is to use a dual fluidized-bed CLC process to complete the oxidation of the

Nitrogen Chemistry in Fluidized Bed Combustion of Coal

DEFF Research Database (Denmark)

Jensen, Anker Degn

and reduction by homogeneous and heterogeneous reactions. The data for the estimation of kinetics of the heterogeneous reactions were measured by one of the partners in the project for char and bed material sampled from a pressurized FBC pilot plant burning Kiveton Park coal. Experimental data from the pilot...... plant were used for model verification. The simulations of the NO emission during staged combustion and NH3 injection for NO reduction were in qualitative agreement with the experimental data. A parametric study of the influence of operating conditions on the conversion of fuel-N to NO showed......, the gas interchange coefficient, the bubble size and the bubble rise velocity. The most important combustion parameters were the rate of CO and CH4 combustion and the fraction of CO produced from char combustion. By using a rate of production analysis, the important reactions in the NO model were...

Combustion from basics to applications

CERN Document Server

Lackner, Maximilian; Winter, Franz

2013-01-01

Combustion, the process of burning, is defined as a chemical reaction between a combustible reactant (the fuel) and an oxidizing agent (such as air) in order to produce heat and in most cases light while new chemical species (e.g., flue gas components) are formed. This book covers a gap on the market by providing a concise introduction to combustion. Most of the other books currently available are targeted towards the experienced users and contain too many details and/or contain knowledge at a fairly high level. This book provides a brief and clear overview of the combustion basics, suitable f

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M.; Kilpinen, P. [Aabo Akademi, Turku (Finland)

1996-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M; Kilpinen, P [Aabo Akademi, Turku (Finland)

1997-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Direct determination of enthalpies of solid phase reactions by immersion method; Determination directe des enthalpies de reaction en phase solide par une methode de plongee

Energy Technology Data Exchange (ETDEWEB)

Roux, A; Richard, M; Eyraud, L; Stevanovic, M; Elston, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-07-01

It is not generally possible to measure the enthalpy change corresponding to solid phase reactions using the dynamic differential thermal analysis method because these reactions are usually too slow at the temperature of operation of present equipment. A ballistic differential thermal analysis apparatus has been developed which is based on an immersion-compensation method; it overcomes the difficulties previously encountered. This apparatus has been used after calibration for determining the enthalpies of formation of calcium and cadmium titanates. and also the Wigner energies of BeO, MgO and Al{sub 2}O{sub 3} samples irradiated at variable dose at a temperature of under 100 deg. C. (authors) [French] Il n'est generalement pas possible de mesurer la variation d'enthalpie correspondant aux reactions en phase solide par la methode d'analyse thermique differentielle dynamique. En effet, ces reactions sont le plus souvent trop lentes aux temperatures d'utilisation des dispositifs actuels. Un appareil d'analyse thermique differentielle balistique, base sur une methode de plongee avec compensation, a ete mis au point et permet de surmonter les difficultes precedentes. Apres etalonnages, cet appareil a ete utilise pour la determination des enthalpies de formation du titanate de calcium et du titanate de cadmium ainsi que pour celle des energies Wigner emmagasinees dans des echantillons de BeO, MgO et Al{sub 2}O{sub 3} irradies a une temperature inferieure a 100 deg. C et a differentes doses. (auteurs)

Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

Science.gov (United States)

Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

2016-03-14

Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

Synthesisofc-lifepo4 composite by solid state reaction method

Science.gov (United States)

Rahayu, I.; Hidayat, S.; Noviyanti, A. R.; Rakhmawaty, D.; Ernawati, E.

2017-02-01

In this research, the enhancement of LiFePO4 conductivity was conducted by doping method with carbon materials. Carbon-based materials were obtained from the mixture of sucrose, and the precursor of LiH2PO4 and α-Fe2O3 was synthesized by solid state reaction. Sintering temperature was varied at 700°C, 800°C, 900°C and 1,000°C. The result showed that C-LiFePO4 could be synthesized by using solid state reaction method. Based on the XRD and FTIR spectrums, C-LiFePO4 can be identified as the type of crystal, characterized by the appearance of sharp signal on (011), (211) and typical peak of LiFePO4 materials. The result of conductivity measurement from C-LiFePO4 at sintering temperature of 900°C and 1,000°C was 2×10-4 S/cm and 4×10-4S/cm, respectively. The conductivity value at sintering temperature of 700°C and 800°C was very small (<10-6 S/cm), which cannot be measured by the existing equipment.

Combustion chemistry - activities in the CHEK research programme

Energy Technology Data Exchange (ETDEWEB)

Dam-Johansen, K.; Johnsson, J.E.; Glarborg, P.; Frandsen, F.; Jensen, A.; Oestberg, M. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

1997-10-01

The combustion chemistry in the oxidation of fossil fuels and biofuels determines together with mixing and heat transfer the required size of a furnace, the emission of gaseous pollutants, and the formation of ash and deposits on surfaces. This presentation describes technologies for solid fuels combustion and gives a summary of the fuels, the pollutant chemistry and the inorganic chemistry in combustion processes. Emphasis is put on the work carried out in the CHEC (Combustion and Harmful Emission Control) Research Programme. (orig.)

Experiment and modeling of low-concentration methane catalytic combustion in a fluidized bed reactor

International Nuclear Information System (INIS)

Yang, Zhongqing; Yang, Peng; Zhang, Li; Guo, Mingnv; Ran, Jingyu

2016-01-01

Highlights: • The catalytic combustion of 0.15~3 vol. % low concentration methane in a fluidized bed was studied. • A mathematical model was proposed on the basis of gas–solid flow theory. • A comparative analysis of the established model with plug flow, mixed flow and K-L models was carried out. • The axial methane profile along fluidized bed was predicted by using the mathematical model. • The bed temperature has greater impact on methane conversion than fluidized velocity. - Abstract: This study undertakes a theoretical analysis and an experimental investigation into the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed reactor using 0.5 wt.% Pd/Al_2O_3 as catalytic particles. A mathematical model is established based on gas–solid flow theory and is used to study the effects of bed temperature and fluidized velocity on methane catalytic combustion, and predict the dimensionless methane concentration axial profile in reactor. It is shown that methane conversion increases with bed temperature, but decreases with increasing fluidized velocity. These theoretical results are found to correlate well with the experimental measurement, with a deviation within 5%. A comparative analysis of the developed model with plug flow, mixed flow and K-L models is also carried out, and this further verifies that the established model better reflects the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed. Using this reaction model, it was found that the difference in methane conversion between dense and freeboard zones gradually increases with bed temperature; the dense zone reaction levels off at 650 °C, thereby minimizing the difference between the dense and freeboard regions to around 15%. With an increase in bed temperature, the dimensionless methane concentration in the dense zone decreases exponentially, while in the splash zone, it varies from an exponential decay to a slow

Investigation of a process for the pyrolysis of plutonium contaminated combustible solid waste

International Nuclear Information System (INIS)

Longstaff, B.; Cains, P.W.; Elliot, M.N.; Taylor, R.F.

1981-01-01

Pyrolysis offers an attractive first-stage alternative to incineration as a means of weight and volume reduction of solide combustible waste P.C.M, if it is required to recover plutonium from the final product. The avoidance of turbulent conditions associated with incineration should lead to less carry-over of particulates, and the lower operating temperature approximately 700 0 C should be most advantageous to the choice of constructional materials and to plant life. The char product from pyrolysis may be oxidised to a final ash at similarly acceptable low temperatures by passing air over a stirred bed of materials. The recently received draft designs for a cyclone after-burner (plus associated scrubbers and filters etc) offer an attractive method of dispensing of the volatile products of pyrolysis

Combustion Characteristics of C5 Alcohols and a Skeletal Mechanism for Homogeneous Charge Compression Ignition Combustion Simulation

KAUST Repository

Park, Sungwoo

2015-10-27

C5 alcohols are considered alternative fuels because they emit less greenhouse gases and fewer harmful pollutants. In this study, the combustion characteristics of 2-methylbutanol (2-methyl-1-butanol) and isopentanol (3-methyl-1-butanol) and their mixtures with primary reference fuels (PRFs) were studied using a detailed chemical kinetic model obtained from merging previously published mechanisms. Ignition delay times of the C5 alcohol/air mixtures were compared to PRFs at 20 and 40 atm. Reaction path analyses were conducted at intermediate and high temperatures to identify the most influential reactions controlling ignition of C5 alcohols. The direct relation graph with expert knowledge methodology was used to eliminate unimportant species and reactions in the detailed mechanism, and the resulting skeletal mechanism was tested at various homogeneous charge compression ignition (HCCI) engine combustion conditions. These simulations were used to investigate the heat release characteristics of the methyl-substituted C5 alcohols, and the results show relatively strong reactions at intermediate temperatures prior to hot ignition. C5 alcohol blending in PRF75 in HCCI combustion leads to a significant decrease of low-temperature heat release (LTHR) and a delay of the main combustion. The heat release features demonstrated by C5 alcohols can be used to improve the design and operation of advanced engine technologies.

Data summary of municipal solid waste management alternatives. Volume 5, Appendix C, Fluidized-bed combustion

Energy Technology Data Exchange (ETDEWEB)

None

1992-10-01

This appendix provides information on fluidized-bed combustion (FBC) technology as it has been applied to municipal waste combustion (MWC). A review of the literature was conducted to determine: (1) to what extent FBC technology has been applied to MWC, in terms of number and size of units was well as technology configuration; (2) the operating history of facilities employing FBC technology; and (3) the cost of these facilities as compared to conventional MSW installations. Where available in the literature, data on operating and performance characteristics are presented. Tabular comparisons of facility operating/cost data and emissions data have been complied and are presented. The literature review shows that FBC technology shows considerable promise in terms of providing improvements over conventional technology in areas such as NOx and acid gas control, and ash leachability. In addition, the most likely configuration to be applied to the first large scale FBC dedicated to municipal solid waste (MSW) will employ circulating bed (CFB) technology. Projected capital costs for the Robbins, Illinois 1600 ton per day CFB-based waste-to-energy facility are competitive with conventional systems, in the range of $125,000 per ton per day of MSW receiving capacity.

Manufacturing of Porous Al-Cr Preforms for Composite Reinforcing Using Microwave Activated Combustion Synthesis

Directory of Open Access Journals (Sweden)

Naplocha K.

2014-10-01

Full Text Available The combustion synthesis of porous skeletons (preforms of intermetallic Al–Cr compounds intended for metal matrix composite MMC reinforcing was developed. Mixture of Al and Cr powders with granularity of −10, −44, −74mm were cold isostatic pressed and next ignited and synthetized in a microwave reactor under argon atmosphere (microwave-activated combustion synthesis MACS. In order to ignite the synthesis, microwave energy was focused by a tuner on the specimen. The analysis of reaction temperature diagrams revealed that the synthesis proceeded through the following peritectic transformations: L(liquidus+Al7Cr→L+Al11Cr2→L+Al4Cr. Moreover, EDS and XRD examinations showed that the reaction proceeded between a solid Cr and a liquid Al to create a distinct envelope of Al9Cr4 on Cr particle which next extended and spreaded over the entire structure. The produced preforms with uniform structure and interconnected porosity were infiltrated with liquid Cu and Al alloy. The obtained composite materials exhibited high hardness, wear and distinct temperature oxidation resistance.

Solid state reaction in alumina nanoparticles/LZSA glass-ceramic composites

International Nuclear Information System (INIS)

Montedo, O.K.; Oliveira, A.N. de; Raupp-Pereira, F.

2016-01-01

Full text: The aim of this work is to present results related to solid state reactions on LZSA glass-ceramic composites containing alumina reinforcement nano-particles. A LZSA (Li2O-ZrO2-SiO2-Al2O3) glass-ceramic has been prepared by sintering of powders and characterized. Composites containing 0 to 77 vol.% of alumina nanoparticles (27-43 nm APS, 35 m2.g-1 SSA) and a 16.9Li2O•5.0ZrO2•65.1SiO2•8.6Al2O3 glass-ceramic matrix have been prepared. X-ray diffractometry studies have been performed in order of investigating the solid state reactions occurring in LZSA-based composites. Results of the XRD patterns have been related to the coefficient of thermal expansion (CTE), Young modulus, and dielectric constant, showing that, in comparison with the glass-ceramic composition, the composites showed a decrease of CTE with the alumina concentration increasing, due to the increasing of beta-spodumeness formation (solid solution of beta-spodumene, Li2O.Al2O3.4-10SiO2). The performance of the glass-ceramic was improved with the alumina nano-particles addition, showing potential of using in the preparation of Low Thermal Co-fired Ceramics (LTCC). (author)

Combustion chemistry. Activities in the CHEC research programme

Energy Technology Data Exchange (ETDEWEB)

Dam-Johansen, K; Johnsson, J E; Glarborg, P; Frandsen, F; Jensen, A; Oestberg, M [Technical Univ. of Denmark, Dept. of Chemical Engineering, Lyngby (Denmark)

1996-12-01

The combustion chemistry in the oxidation of fossil fuels and biofuels determines together with mixing and heat transfer the required size of a furnace, the emission of gaseous pollutants, and the formation of ash and deposits on surfaces. This paper describes technologies for solid fuels combustion and gives a summary of the fuels, the pollutant chemistry and the inorganic chemistry in combustion processes. Emphasis is put on the work carried out in the CHEC (Combustion and Harmful Emission Control Research Programme). (au) 173 refs.

Large-eddy simulation of ethanol spray combustion using a finite-rate combustion model

Energy Technology Data Exchange (ETDEWEB)

Li, K.; Zhou, L.X. [Tsinghua Univ., Beijing (China). Dept. of Engineering Mechanics; Chan, C.K. [Hong Kong Polytechnic Univ. (China). Dept. of Applied Mathematics

2013-07-01

Large-eddy simulation of spray combustion is under its rapid development, but the combustion models are less validated by detailed experimental data. In this paper, large-eddy simulation of ethanol-air spray combustion was made using an Eulerian-Lagrangian approach, a subgrid-scale kinetic energy stress model, and a finite-rate combustion model. The simulation results are validated in detail by experiments. The LES obtained statistically averaged temperature is in agreement with the experimental results in most regions. The instantaneous LES results show the coherent structures of the shear region near the high-temperature flame zone and the fuel vapor concentration map, indicating the droplets are concentrated in this shear region. The droplet sizes are found to be in the range of 20-100{mu}m. The instantaneous temperature map shows the close interaction between the coherent structures and the combustion reaction.

Numerical analysis of the thermo-fluid-dynamic field in the combustion chamber of an incinerator plant

International Nuclear Information System (INIS)

Costa, M.; Dell'Isola, M.; Massarotti, N.

2009-01-01

As the interest for energy recovery from waste incineration has increased over the years, concern for the impact such processes have on the environment has also grown. To reduce such an impact, the legislation enforced in Italy and Europe imposes important restrictions on the temperature of the exhausts in the combustion chamber, which must be kept above certain values depending on the type of waste that is being incinerated, for a given period of time. Such conditions can be rather difficult and certainly very expensive to monitor with acceptable accuracy. In this work, a numerical approach is presented for modelling waste combustion in a full scale incineration plant. Both solid and gas phase reactions are considered. Various modes of heat and mass transfer between the waste bed, the air and the combustion products are taken into account, as well as radiation from the combustion chamber walls and the combustion products. The temperature distribution in the combustion chamber is obtained considering either forced or mixed convection. It is therefore shown that neglecting buoyancy effects may lead to appreciable errors. Verification of the code performance is based on comparison with the results of an experimental campaign at a full scale plant in Italy.

Direct synthesis of La9.33Si6O26 ultrafine powder via sol-gel self-combustion method

International Nuclear Information System (INIS)

Tian Changan; Liu Junliang; Cai Jun; Zeng Yanwei

2008-01-01

Single phase La 9.33 Si 6 O 26 ultrafine powder, as a kind of highly activated precursor to prepare medium-to-low temperature electrolyte for solid oxide fuel cells (SOFCs), has been successfully synthesized via a non-aqueous sol-gel and self-combustion approach from the starting materials: lanthanum nitrate (La(NO 3 ) 3 .6H 2 O), citric acid, ethylene glycol (EG), tetraethyl orthosilicate (TEOS) and ammonium nitrate. The details of gel's self-combustion were investigated by DTA-TG and the structural characterization of as-synthesized powder from self-combustion was performed by XRD and SEM. The results show that La 9.33 Si 6 O 26 single phase of apatite-type crystal structure can be directly synthesized by sol-gel self-combustion method without further calcinations on the condition that the molar ratio (R) of NO 3 - to citric acid and ethylene glycol being 6:1. Such powders composed of well-dispersed particles with an average size of 200 nm and a specific surface area of 5.54 m 2 /g. It can be sintered to 90% of its theoretical density at 1500 deg. C for 10 h, about 200 deg. C lower than the sintering temperature for the powder derived from traditional solid reactions. The sintered material has a thermal expansion coefficient of 9.2 x 10 -6 K -1 between room temperature and 800 deg. C

The Effects of Combustion Parameters on Pollutant Emissions in a Porous Burner

Directory of Open Access Journals (Sweden)

Negin Moallemi Khiavi

2014-06-01

Full Text Available This paper reports a two-dimensional numerical prediction of premixed methane/air combustion in inert porous media. The two dimensional Navier-stokes equations, the two separate energy equations for solid and gas and conservation equations for chemical species are solved using finite volume method based on SIMPLE algorithm. The burner under study is a rectangular one with two different regions. First region is a preheating zone (low porosity matrix that followed by the actual combustion region (high porosity matrix. For simulating the chemical reactions, skeletal mechanism (26 species and 77 reactions is used. For studying the pollutant emissions in this porous burner, the effects of porous matrix properties, excess air ratio and inlet velocity are studied. The predicted gas temperature contour and pollutant formations are in good agreement with the available experimental data. The results indicate that the downstream of the burner should be constructed from materials with high conductivity, high convective heat transfer coefficient and high porosity in order to decrease the CO and NO emissions. Also, with increasing the inlet velocity of gas mixture and the excess air ratio, the pollutant emissions are decreased.

Quantitative Measurement of Oxygen in Microgravity Combustion

Science.gov (United States)

Silver, Joel A.

1997-01-01

A low-gravity environment, in space or in ground-based facilities such as drop towers, provides a unique setting for studying combustion mechanisms. Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for better characterization of dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Due to restrictions associated with performing measurements in reduced gravity, diagnostic methods which have been applied to microgravity combustion studies have generally been limited to capture of flame emissions on film or video, laser Schlieren imaging and (intrusive) temperature measurements using thermocouples. Given the development of detailed theoretical models, more sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion processes as well as provide accurate feedback to improve the predictive capabilities of the models. When the demands of space flight are considered, the need for improved diagnostic systems which are rugged, compact, reliable, and operate at low power becomes apparent. The objective of this research is twofold. First, we want to develop a better understanding of the relative roles of diffusion and reaction of oxygen in microgravity combustion. As the primary oxidizer species, oxygen plays a major role in controlling the observed properties of flames, including flame front speed (in solid or liquid flames), extinguishment characteristics, flame size and flame temperature. The second objective is to develop better diagnostics based on diode laser absorption which can be of real value in both microgravity combustion research and as a sensor on-board Spacelab as either an air quality monitor or as part of a fire detection system. In our prior microgravity work, an eight line-of-sight fiber optic system measured

Synthesis and sintering Ni-Zn ferrite obtained for combustion reaction in large scale

International Nuclear Information System (INIS)

Vieira, D.A.; Diniz, V.C.S.; Costa, A.C.F.M.; Cornejo, D.R.; Kiminami, R.H.G.A.

2014-01-01

This research proposes to evaluate the magnetic properties of ferrite Ni-Zn synthesized by combustion reaction on a large scale and sintered at 1250 deg C in resistive furnace. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and magnetic measurements. The results show that the synthesized product in large scale resulted in soft magnetic material with saturation magnetization of 40 emu·g"-"1 and coercivity of 0.080 kOe, after sintering it was observed an increase to 68 emu·g"-"1 in the magnetization and a reduction to 0.016 kOe in coercivity, indicating that the obtained material has promising characteristics for applications in electro-electronic devices. (author)

The redox reaction kinetics of Sinai ore for chemical looping combustion applications

International Nuclear Information System (INIS)

Ksepko, Ewelina; Babiński, Piotr; Nalbandian, Lori

2017-01-01

Highlights: • Redox reaction kinetics of Fe-Mn-rich Sinai ore was determined by TGA. • The most suitable model for reduction was D3, while R3 for oxidation. • Activation energies 35.3 and 16.70 kJ/mole were determined for reduction and oxidation. • Repetitive redox reactions favor the formation of spinel phases in Sinai ore. • Multiple redox cycles induce formation of extensive porosity of the particles. - Abstract: The objective of this work was to study the use of Sinai ore, a Fe–Mn-based ore from Egypt, as a low-cost oxygen carrier (OC) in Chemical Looping Combustion (CLC). The Sinai ore was selected because it possesses relatively high amounts of iron and manganese oxides. Furthermore, those oxides have low cost, very favorable environmental and thermodynamic properties for the CLC process. The performance of the Sinai ore as an OC in CLC was compared to that of ilmenite (Norway Tellnes mine), the most extensively studied naturally occurring Fe-based mineral. The kinetics of the reduction and oxidation reactions with the two minerals were studied using a thermogravimetric analyzer (TGA). Experiments were conducted under isothermal conditions, with multiple redox cycles, at temperatures between 750 and 950 °C. For the reduction and oxidation reactions, different concentrations of CH_4 (10–25 vol.%) and O_2 (5–20 vol.%) were applied, respectively. The kinetic parameters, such as the activation energy (E_a), pre-exponential factor (A_0), and reaction order (n), were determined for the redox reactions. Furthermore, models of the redox reactions were selected by means of a model-fitting method. For the Sinai ore, the D3 model (3-dimensional diffusion) was suitable for modeling reduction reaction kinetics. The calculated E_a was 35.3 kJ/mole, and the reaction order was determined to be approximately 0.76. The best fit for the oxidation reaction was obtained for the R3 model (shrinking core). The oxidation (regeneration) reaction E_a was equal to 16

Researches concerning the use of mixed Hydrogen in the combustion of dense biomass

International Nuclear Information System (INIS)

Negreanu, Gabriel-Paul; Mihaescu, Lucian; Pisa, Ionel; Berbece, Viorel; Lazaroiu, Gheorghe

2014-01-01

The paper deals with theoretical basis and experimental tests of mixed hydrogen diffusion in the dense system of biomass. Research regarding hydrogen diffusion in the porous system of biomass is part of wider research focusing on using hydrogen as an active medium for solid biomass combustion. In parallel with hydrogen diffusion in solid biomass, tests regarding biomass combustion previously subjected to a hydrogen flux will be carried out. Keywords: biomass, hydrogen diffusion, combustion, experimental tests

Chemical Looping Combustion Reactions and Systems

Energy Technology Data Exchange (ETDEWEB)

Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

2011-07-01

Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO2 capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This work focused on two classes of oxygen carrier, one that merely undergoes a change in oxidation state, such as Fe3O4/Fe2O3 and one that is converted from its higher to its lower oxidation state by the release of oxygen on heating, i.e., CuO/Cu2O. This topical report discusses the results of four complementary efforts: (1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification (3) the exploration of operating characteristics in the laboratory-scale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability (4) the identification of mechanisms and rates for the copper, cuprous oxide, and cupric oxide system using thermogravimetric analysis.

Multi-User Hardware Solutions to Combustion Science ISS Research

Science.gov (United States)

Otero, Angel M.

2001-01-01

In response to the budget environment and to expand on the International Space Station (ISS) Fluids and Combustion Facility (FCF) Combustion Integrated Rack (CIR), common hardware approach, the NASA Combustion Science Program shifted focus in 1999 from single investigator PI (Principal Investigator)-specific hardware to multi-user 'Minifacilities'. These mini-facilities would take the CIR common hardware philosophy to the next level. The approach that was developed re-arranged all the investigations in the program into sub-fields of research. Then common requirements within these subfields were used to develop a common system that would then be complemented by a few PI-specific components. The sub-fields of research selected were droplet combustion, solids and fire safety, and gaseous fuels. From these research areas three mini-facilities have sprung: the Multi-user Droplet Combustion Apparatus (MDCA) for droplet research, Flow Enclosure for Novel Investigations in Combustion of Solids (FEANICS) for solids and fire safety, and the Multi-user Gaseous Fuels Apparatus (MGFA) for gaseous fuels. These mini-facilities will develop common Chamber Insert Assemblies (CIA) and diagnostics for the respective investigators complementing the capability provided by CIR. Presently there are four investigators for MDCA, six for FEANICS, and four for MGFA. The goal of these multi-user facilities is to drive the cost per PI down after the initial development investment is made. Each of these mini-facilities will become a fixture of future Combustion Science NASA Research Announcements (NRAs), enabling investigators to propose against an existing capability. Additionally, an investigation is provided the opportunity to enhance the existing capability to bridge the gap between the capability and their specific science requirements. This multi-user development approach will enable the Combustion Science Program to drive cost per investigation down while drastically reducing the time

Process gas generator feeding internal combustion piston engines

Energy Technology Data Exchange (ETDEWEB)

Iwantscheff, G; Kostka, H; Henkel, H J

1978-10-26

The invention relates to a process gas generator feeding gaseous fuel to internal combustion piston engines. The cylinder linings of the internal combustion engine are enclosed by the catalytic reaction chamber of the process gas generator which contains perforated sintered nozzle bricks as carriers of the catalysts needed for the conversion. The reaction chamber is surrounded by the exhaust gas chamber around which a tube coil is ound which feeds the fuel charge to the reaction chamber after evaporation and mixing with exhaust gas and air. The fuel which may be used for this purpose, e.g., is low-octane gasoline or diesel fuel. In the reaction chamber the fuel is catalytically converted at temperatures above 200/sup 0/C, e.g., into low-molecular paraffins, carbon monoxide and hydrogen. Operation of the internal combustion engine with a process gas generator greatly reduces the pollutant content of the exhaust gases.

CuInSe2 nano-crystallite reaction kinetics using solid state reaction from Cu2Se and In2Se3 powders

International Nuclear Information System (INIS)

Hsiang, Hsing-I; Lu, Li-Hsin; Chang, Yu-Lun; Ray, Dahtong; Yen, Fu-Su

2011-01-01

Highlights: → CuInSe 2 phase increased gradually accompanied with a decrease in γ-In 2 Se 3 and no intermediate phase during calcination. → CuInSe 2 formation from Cu 2 Se and In 2 Se 3 powders follows a one-dimensional diffusion-controlled reaction with apparent activation energy of about 122.5 kJ/mol. → The solid reaction kinetics may be dominated by the diffusion of In 3+ ions. - Abstract: The reaction mechanism and CuInSe 2 formation kinetics using a solid state reaction from Cu 2 Se and In 2 Se 3 powders synthesized using a heating up process were investigated using X-ray diffractomy (XRD) and transmission electron microscopy (TEM). It was observed that the CuInSe 2 phase increased gradually, accompanied with a decrease in γ-In 2 Se 3 with no intermediate phase as the calcination temperature and soaking time were increased. The reaction kinetics was analyzed using the Avrami and polynomial kinetic model, suggesting that CuInSe 2 formation from Cu 2 Se and In 2 Se 3 powders follows a diffusion-controlled reaction with an apparent activation energy of about 122.5-182.3 kJ/mol. Cu 2 Se and In 2 Se 3 phases react and directly transform into CIS without the occurrence of any intermediate phase and the size of the newly formed CuInSe 2 crystallites was close to that of the Cu 2 Se reactant particle based on the TEM results, which indicated that the solid reaction kinetics may be dominated by the diffusion of In 3+ ions.

PCDD/PCDF reduction by the co-combustion process.

Science.gov (United States)

Lee, Vinci K C; Cheung, Wai-Hung; McKay, Gordon

2008-01-01

A novel process, termed the co-combustion process, has been developed and designed to utilise the thermal treatment of municipal solid waste (MSW) in cement clinker production and reduce PCDD/PCDF emissions. To test the conceptual design; detailed engineering design of the process and equipment was performed and a pilot plant was constructed to treat up to 40 tonnes MSW per day. The novel process features included several units external to the main traditional cement rotary kiln: an external calcinations unit in which the hot gas calcined the limestone thus making significant energy savings for this chemical reaction; the lime generated was used in a second chamber to act as a giant acid gas scrubber to remove SOx and particularly HCl (a source of chloride); an external rotary kiln and secondary combustion unit capable of producing a hot gas at 1200 degrees C; a gas cooler to simulate a boiler turbogenerator set for electricity generation; the incorporation of some of the bottom ash, calcined lime and dust collector solids into the cement clinker. A PCDD/PCDF inventory has been completed for the entire process and measured PCDD/PCDF emissions were 0.001 ng I-TEQ/Nm(3) on average which is 1% of the best practical means [Hong Kong Environmental Protection Department, 2001. A guidance note on the best practicable means for incinerators (municipal waste incineration), BPM12/1] MSW incineration emission limit values.

Growth behavior of LiMn2O4 particles formed by solid-state reactions in air and water vapor

International Nuclear Information System (INIS)

Kozawa, Takahiro; Yanagisawa, Kazumichi; Murakami, Takeshi; Naito, Makio

2016-01-01

Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn 2 O 4 particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn 2 O 4 particles in air and water vapor atmospheres as model reactions; LiMn 2 O 4 is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO 3 precursor impregnated with LiOH, LiMn 2 O 4 spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn 2 O 4 particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn 2 O 4 particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

Municipal solid waste combustion: Fuel testing and characterization

Energy Technology Data Exchange (ETDEWEB)

Bushnell, D.J.; Canova, J.H.; Dadkhah-Nikoo, A.

1990-10-01

The objective of this study is to screen and characterize potential biomass fuels from waste streams. This will be accomplished by determining the types of pollutants produced while burning selected municipal waste, i.e., commercial mixed waste paper residential (curbside) mixed waste paper, and refuse derived fuel. These materials will be fired alone and in combination with wood, equal parts by weight. The data from these experiments could be utilized to size pollution control equipment required to meet emission standards. This document provides detailed descriptions of the testing methods and evaluation procedures used in the combustion testing and characterization project. The fuel samples will be examined thoroughly from the raw form to the exhaust emissions produced during the combustion test of a densified sample.

Combustion science and engineering

CERN Document Server

Annamalai, Kalyan

2006-01-01

Introduction and Review of Thermodynamics Introduction Combustion Terminology Matter and Its Properties Microscopic Overview of Thermodynamics Conservation of Mass and Energy and the First Law of Thermodynamics The Second Law of Thermodynamics Summary Stoichiometry and Thermochemistry of Reacting Systems Introduction Overall Reactions Gas Analyses Global Conservation Equations for Reacting Systems Thermochemistry Summary Appendix Reaction Direction and Equilibrium Introduction Reaction Direction and Chemical Equilibrium Chemical Equilibrium Relations Vant Hoff Equation Adi

Process for producing volatile hydrocarbons from hydrocarbonaceous solids

Energy Technology Data Exchange (ETDEWEB)

1949-02-03

In a process for producing volatile hydrocarbons from hydrocarbonaceous solids, a hydrocarbonaceus solid is passed in subdivided state and in the form of a bed downwardly through an externally unheated distilling retort wherein the evolution of volatiles from the bed is effected while solid material comprising combustible heavy residue is discharged from the lower portion of the bed and retort, combustibles are burned from the discharged solid material. The admixture resultant combustion gases with the vapours evolved in the retort is prevented, and a stream of hydrocarbon fluid is heated by indirect heat exchange with hot combustion gases produced by burning to a high temperature and is introduced into the distilling retort and direct contact with bed, supplying heat to the latter for effecting the evolution of volatiles from the hydrocarbonaceous solid. The improvement consists of subjecting the volatile distillation products evolved and removed from the bed to a fractionation and separating selected relatively light and heavy hydrocarbon fractions from the distillation products, withdrawing at least one of the selected fractions from the prcess as a product heating at least one other of the selected fractions to high temperature by the indirect heat exchange with hot combustion gases, and introducing the thus heated hydrocarbon fraction into direct contact with the bed.

Development of a new reduced hydrogen combustion mechanism with NO_x and parametric study of hydrogen HCCI combustion using stochastic reactor model

International Nuclear Information System (INIS)

Maurya, Rakesh Kumar; Akhil, Nekkanti

2017-01-01

Highlights: • PDF based stochastic reactor model used for study of hydrogen HCCI engine. • New reduced hydrogen combustion mechanism with NOx developed (30 species and 253 reactions). • Mechanism predicts cylinder pressure and captures NO_x emission trend with sufficient accuracy. • Parametric study of hydrogen HCCI engine over wide range of speed and load conditions. • Hydrogen HCCI operating range increases with compression ratio & decreases with engine speed. - Abstract: Hydrogen is a potential alternative and renewable fuel for homogenous charge compression ignition (HCCI) engine to achieve higher efficiency and zero emissions of CO, unburned hydrocarbons as well as other greenhouse gases such as CO_2 and CH_4. In this study, a detailed hydrogen oxidation mechanism with NO_x was developed by incorporating additional species and NO_x reactions to the existing hydrogen combustion mechanism (10 species and 40 reactions). The detailed hydrogen combustion mechanism used in this study consists of 39 species and 311 reactions. A reduced mechanism consisting 30 species and 253 reactions was also developed by using directed relation graph (DRG) method from detailed mechanism. Developed mechanisms were validated with experimental data by HCCI engine simulation using stochastic reactor model. Sensitivity analysis was performed to identify the most important reactions in hydrogen combustion and NO_x formation in HCCI engine. Pathway analysis was also performed to analyze the important reaction pathways at different temperatures. Results revealed that H2 + HO2 [=] H + H2O2 and O2 + NNH [=] N2 + HO2 are the most significant reactions in the hydrogen HCCI combustion and NO_x formation respectively. Detailed parametric study of HCCI combustion was conducted using developed chemical kinetic model. Numerical simulations are performed at different engine operating condition by varying engine speed (1000–3000 rpm), intake air temperature (380–460 K), and compression

Reaction of hydrogen atoms produced by radiolysis and photolysis in solid phase at 4 and 77 K

International Nuclear Information System (INIS)

Miyazaki, Tetsuo

1991-01-01

The behavior of H atoms in the solid phase has been reviewed with special attention to comparison of H atoms produced by radiolysis with those produced by photolysis. The paper consists of three parts. I -Production of H atoms: (1) the experimental results which indicate H-atom formation in the radiolysis of solid alkane are summarized; (2) ESR saturation behavior of trapped H atoms depends upon the method of H-atom-production, i.e. photolysis or radiolysis, and upon the initial energy of H atoms in the photolysis. II - Diffusion of H atoms: (1) activation energies for thermally-activated diffusion of H atoms are shown; (2) quantum diffusion of H atoms in solid H 2 is explained in terms of repetition of tunneling reaction H 2 + H → H + H 2 . III -Reaction of H atoms: (1) reactions and trapping processes of hot H atoms have been shown in solid methane and argon by use of hot H atoms with specified initial energy; (2) when H atoms are produced by the radiolysis of solvent alkane or by the photolysis of HI in the alkane mixtures at 77 K, the H atoms react very selectively with solute alkane at low concentration. The selective reaction of the H atom has been found in eight matrices; (3) activation energy for a hydrogen-atom-abstraction reaction by thermal H atoms at low temperatures is less than than several kJ mol -1 because of quantum tunneling. The absolute rate constants for H 2 (D 2 , HD) + H(D) tunneling reactions have been determined experimentally in solid hydrogen at 4.2K; (4) theoretical studies for tunneling reactions H 2 (D 2 ,HD) + H(D) at ultralow temperatures were reviewed. The calculated rate constants were compared with the rate constants obtained experimentally. (author)

Chemical Processes Related to Combustion in Fluidised Bed

Energy Technology Data Exchange (ETDEWEB)

Steenari, Britt-Marie; Lindqvist, Oliver [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Environmental Inorganic Chemistry

2002-12-01

This report covers work that has been carried out in the combustion chemistry group at the Dept. of Environmental Inorganic Chemistry, Chalmers, within the STEM project 12859-1, during the period 2000-07-01 to 2002-06-30. The work was comprised of the following parts: Sulphur chemistry under pressurised and atmospheric conditions; Gas/solid reactions related to sintering and fouling; Chemistry of volatile metals in combustion; Ash leaching properties; Theoretical modelling of the interactions between ions in a solution and mineral surfaces; Some related issues and co-operations with other departments. The work on sulphur chemistry has been a central issue in our group and it has now been finalised with a PhD thesis discussing some aspects of the sulphation of limestone under pressurised conditions. The influence of a number of parameters on the sulphation efficiency was investigated and compared with similar studies under atmospheric conditions. In a special study it was shown that the influence of alternating calcining - non-calcining conditions on the conversion was substantial. In addition, the oxidation of CaS and sulphided limestone was studied and a regeneration method for the sulphide sorbent was proposed. In the project part concerning gas - solid reactions that are relevant to sintering and fouling, the application of an on-line measurement technique for the study of alkali metal capture by kaolin or other sorbents is described. A new reactor set-up has been constructed and the initial results from this set up are promising. The chemistry of cadmium in combustion of MSW and biomass is the object of a PhD project. This work has been concentrated on the task of identifying Cd-compounds in fly ash samples. It has now come to a point where enough data has been collected to make it possible to give an indication about the Cd speciation in some ash types. In MSW ash particles, cadmium seem to occur mainly as chloride, oxide and sulphate. The work will continue

Leaching of coal solid waste; Lixiviacion de Residuos de Combustion de Carbon

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

Combustion process to generate electrical energy in Thermal power Stations causes a big volume of solid wastes. Their store and removal has to be check for possible risks in the Environment. In this study, ashes and slags from eleven Spanish Thermal power Station has been selected. Physical chemical assays have been developed for determining twenty four parameters by; ionic chromatography, atomic absorption spectrophotometry liquid chromatography. (HPLC): UV and selective electrodes, selective electrodes espectrophotometry. Moreover, six biological tests have been realized: Bioluminescence with Photobacterium phosphoreum, Daphnia magna assay. Inhibition on Algae, Inhibition of respiration of Activated Sludges, Acute Toxicity on Fish and Earth-worm Toxicity tests. Samples treatment has been carrying out by two leaching methods: 1 o EP and DIN 38414-4 No toxic level has been found for physical-chemical parameters. The CE50 values of biological tests have allowed to stablish organisms sensibilities to waste samples, differences between ashes and slags and relationship between the carbon type and his effects on the biological organisms. (Author)

Combustion of solid alternative fuels in the cement kiln burner

DEFF Research Database (Denmark)

Nørskov, Linda Kaare

In the cement industry there is an increasing environmental and financial motivation for substituting conventional fossil fuels with alternative fuels, being biomass or waste derived fuels. However, the introduction of alternative fuels may influence emissions, cement product quality, process...... stability, and process efficiency. Alternative fuel substitution in the calciner unit has reached close to 100% at many cement plants and to further increase the use of alternative fuels rotary kiln substitution must be enhanced. At present, limited systematic knowledge of the alternative fuel combustion...... properties and the influence on the flame formation is available. In this project a scientific approach to increase the fundamental understanding of alternative fuel conversion in the rotary kiln burner is employed through literature studies, experimental combustion characterisation studies, combustion...

Synthesis by combustion reaction of ZnAl2O4 and application in methyl alcoholysis of soybean oil

International Nuclear Information System (INIS)

Dantas, B.B.; Silva, A.S.; Cunha, R.B.L.; Leal, E.; Costa, A.C.F.M.

2011-01-01

Biodiesel currently presents itself as a viable alternative to diesel oil front. However, implementation of actions most economic use as heterogeneous catalysts, allows further reduction of this biofuel by procedural steps. This work was supported application of catalytic ZnAl 2 O 4 obtained by combustion reaction in methyl alcoholysis of soybean oil. Samples of the supports were characterized by XRD, textural analysis by nitrogen adsorption and FTIR. The reaction tests were performed at 200°C, molar ratio 1:25, 2 and 4 wt% of catalyst and reaction time of 3 hours. XRD results indicate that the phase was obtained ZnAl 2 O 4 effectively, with surface areas of 14.9 and 8.6 m 2 g -1 . The tests demonstrated that reactional higher content of ester was 56.1 and 63.1% for the percentage of catalyst 2 and 4% respectively. (author)

CATALYTIC COMBUSTION OF METHANE OVER Pt/γ-Al2O3 IN MICRO-COMBUSTOR WITH DETAILED CHEMICAL KINETIC MECHANISMS

Directory of Open Access Journals (Sweden)

JUNJIE CHEN

2014-11-01

Full Text Available Micro-scale catalytic combustion characteristics and heat transfer processes of preheated methane-air mixtures (φ = 0.4 in the plane channel were investigated numerically with detailed chemical kinetic mechanisms. The plane channel of length L = 10.0 mm, height H =1.0 mm and wall thickness δ = 0.1 mm, which inner horizontal surfaces contained Pt/γ-Al2O3 catalyst washcoat. The computational results indicate that the presence of the gas phase reactions extends mildly the micro-combustion stability limits at low and moderate inlet velocities due to the strong flames establishment, and have a more profound effect on extending the high-velocity blowout limits by allowing for additional heat release originating mainly from the incomplete CH4 gas phase oxidation in the plane channel. When the same mass flow rate (ρin × Vin is considered, the micro-combustion stability limits at p: 0.1 MPa are much narrower than at p: 0.6 MPa due to both gas phase and catalytic reaction activities decline with decreasing pressure. Catalytic micro-combustor can achieve stable combustion at low solid thermal conductivity ks < 0.1 W∙m-1•K-1, while the micro-combustion extinction limits reach their larger extent for the higher thermal conductivity ks = 20.0-100.0 W∙m-1•K-1. The existence of surface radiation heat transfers significantly effects on the micro-combustion stability limits and micro-combustors energy balance. Finally, gas phase combustion in catalytic micro-combustors can be sustained at the sub-millimeter scale (plane channel height of 0.25 mm.

High temperature magnetic properties of Co(FeY){sub 2}O{sub 4} synthesized by combustion reaction

Energy Technology Data Exchange (ETDEWEB)

Alves, Thiago Eduardo Pereira, E-mail: thiago.ifgo@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFGO), Goiania (Brazil); Franco Junior, Adolfo [Universidade Federal de Goias (UFG), Goiania (Brazil)

2016-07-01

Full text: Cobalt ferrite is widely studied due to its interesting magnetic behavior at room temperature. However, many technical applications require temperatures that are above that. Thus, it is necessary to understand how some magnetic properties, such as saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc), may behave at high temperatures [1]. Among several methods to synthesize cobalt ferrites, combustion reaction method is intensively used because it is inexpensive, fast and has good control on the stoichiometry. This method is based on the chemistry of propellants and explosives [2]. Therefore, we have prepared a series of nanoparticles of CoFe{sub (2-x)}Y{sub x}O{sub 4}, with x ranging from 0.00 to 0.04, by combustion reaction method. The crystal structure and morphology were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscopy (TEM), respectively. Nanocrystalline particles structures in the typical phase of spinel were observed on diffractograms. Micrographies showed high crystalline powders for the particles and particles size within nanoscale range. The magnetic properties were measured by vibrating sample magnetometry (VSM) in broad range of temperature (300-850K). Saturation magnetization (Ms) decreases with Y doping increase, while Hc increases, being about 1.8 higher than the undoped sample. Furthermore, Curie temperature increases with Y doping increase. These magnetic properties were discussed in terms of the particle interactions induced by the thermal fluctuations, cation distribution, and ions exchange between yttrium and cobalt atoms in A-B sites in the cubic structure [3]. References: [1] A. Franco, Jr. and F. C. e Silva, Applied Physics Letters 96, 172505, (2010). 525 [2] S.R. Jain, et al, Combustion and flame 40, 71-79, (1981). [3] A. Franco Jr. et al. Journal of Alloys and Compounds 680, 198-205, (2016). (author)

Analysis of combustion efficiency in a pelletizing furnace

Directory of Open Access Journals (Sweden)

Rafael Simões Vieira de Moura

Full Text Available Abstract The objective of this research is to assess how much the improvement in the combustion reaction efficiency can reduce fuel consumption, maintaining the same thermal energy rate provided by the reaction in a pelletizing furnace. The furnace for pelletizing iron ore is a complex thermal machine, in terms of energy balance. It contains recirculation fan gases and constant variations in the process, and the variation of a single process variable can influence numerous changes in operating conditions. This study demonstrated how the main variables related to combustion in the burning zone influence fuel consumption (natural gas from the furnace of the Usina de Pelotização de Fábrica (owned by VALE S/A, without changing process conditions that affect production quality. Variables were analyzed regarding the velocity and pressure of the fuel in the burners, the temperature of the combustion air and reactant gases, the conversion rate and the stoichiometric air/fuel ratio of the reaction. For the analysis, actual data of the furnace in operation was used, and for the simulation of chemical reactions, the software Gaseq® was used. The study showed that the adjustment of combustion reaction stoichiometry provides a reduction of 9.25% in fuel consumption, representing a savings of US$ 2.6 million per year for the company.

Investigation of a Boiler's Furnace Aerodynamics with a Vortex Solid Fuel Combustion Scheme on Physical and Mathematical Models

Directory of Open Access Journals (Sweden)

Prokhorov V.B.,

2018-04-01

Full Text Available The important problem of developing the low-cost technologies that will be able to provide a deep decrease in the concentration of nitrogen oxides while maintaining fuel burn-up efficiency is considered. This paper presents the results of the aerodynamics study of the furnace of boiler TPP-210A on the base of the physical and mathematical models in the case when boiler retrofitting from liquid to solid slag removal with two to three times reduction of nitrogen oxide emissions and replacing the vortex burners with direct-flow burners. The need for these studies is due to the fact that the direct-flow burners are "collective action" burners, and efficient fuel combustion can be provided only by the interaction of fuel jets, secondary and tertiary air jets in the furnace volume. The new scheme of air staged combustion in a system of vertical vortexes of opposite rotation with direct-flow burners and nozzles and direct injection of Kuznetsky lean coal dust was developed. In order to test the functional ability and efficiency of the proposed combustion scheme, studies on the physical model of the boiler furnace and the mathematical model of the experimental furnace bench for the case of an isothermal fluid flow were carried out. Comparison showed an acceptable degree of coincidence of these results. In all studied regimes, pronounced vortices remain in both the vertical and horizontal planes, that indicates a high degree of mass exchange between jets and combustion products and the furnace aerodynamics stability to changes in regime factors.

Boris Novozhilov: Life and contribution to the physics of combustion

Science.gov (United States)

Novozhilov, Vasily

2018-04-01

Professor Boris Novozhilov (1930-2017) passed away on February 19th, 2017 in Moscow. The present paper provides brief account of his life and contributions to the physics of combustion. From extensive scientific legacy left by Boris, several major achievements are discussed here: Zeldovich-Novozhilov (ZN) theory of unsteady solid propellant combustion, contributions to thermal explosion theory, the theory of spin combustion, discovery of propellant combustion transition to chaotic regimes through Feigenbaum period bifurcation scenario.

Nordic seminar on biomass gasification and combustion

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

The report comprises a collection of papers from a seminar arranged as a part of the Nordic Energy Research Program. The aim of this program is to strengthen the basic competence in the energy field at universities and research organizations in the Nordic countries. In the program 1991-1994 six areas are selected for cooperation such as energy and society, solid fuels, district heating, petroleum technology, bioenergy and environment, and fuel cells. The topics deal both with biomass combustion and gasification, and combustion of municipal solid waste (MSW) and refuse derived fuel (RDF). A number of 11 papers are prepared. 97 refs., 91 figs., 11 tabs.

Nordic seminar on biomass gasification and combustion

International Nuclear Information System (INIS)

1993-01-01

The report comprises a collection of papers from a seminar arranged as a part of the Nordic Energy Research Program. The aim of this program is to strengthen the basic competence in the energy field at universities and research organizations in the Nordic countries. In the program 1991-1994 six areas are selected for cooperation such as energy and society, solid fuels, district heating, petroleum technology, bioenergy and environment, and fuel cells. The topics deal both with biomass combustion and gasification, and combustion of municipal solid waste (MSW) and refuse derived fuel (RDF). A number of 11 papers are prepared. 97 refs., 91 figs., 11 tabs

Nordic seminar on biomass gasification and combustion

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-12-31

The report comprises a collection of papers from a seminar arranged as a part of the Nordic Energy Research Program. The aim of this program is to strengthen the basic competence in the energy field at universities and research organizations in the Nordic countries. In the program 1991-1994 six areas are selected for cooperation such as energy and society, solid fuels, district heating, petroleum technology, bioenergy and environment, and fuel cells. The topics deal both with biomass combustion and gasification, and combustion of municipal solid waste (MSW) and refuse derived fuel (RDF). A number of 11 papers are prepared. 97 refs., 91 figs., 11 tabs.

Thermogravimetric analysis of biowastes during combustion

International Nuclear Information System (INIS)

Otero, M.; Sanchez, M.E.; Gomez, X.; Moran, A.

2010-01-01

The combustion of sewage sludge (SS), animal manure (AM) and the organic fraction of municipal solid waste (OFMSW) was assessed and compared with that of a semianthracite coal (SC) and of a PET waste by thermogravimetric (TG) analysis. Differences were found in the TG curves obtained for the combustion of these materials accordingly to their respective proximate analysis. Non-isothermal thermogravimetric data were used to assess the kinetics of the combustion of these biowastes. The present paper reports on the application of the Vyazovkin model-free isoconversional method for the evaluation of the activation energy necessary for the combustion of these biowastes. The activation energy related to SS combustion (129.1 kJ/mol) was similar to that corresponding to AM (132.5 kJ/mol) while the OFMSW showed a higher value (159.3 kJ/mol). These values are quite higher than the one determined in the same way for the combustion of SC (49.2 kJ/mol) but lower than that for the combustion of a PET waste (165.6 kJ/mol).

Electron transfer reactions in microporous solids. Progress report, September 1990--January 1993

Energy Technology Data Exchange (ETDEWEB)

Mallouk, T.E.

1993-01-01

Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H{sub 2} and I{sub 3}{sup {minus}}, or H{sub 2} and O{sub 2)} from each other. Spectroscopic and electrochemical methods are used to study the kinetics of electron transfer reactions in these hybrid molecular/solid state assemblies.

Combustion of palm oil solid waste in fluidized bed combustor

International Nuclear Information System (INIS)

Abdullah, I.; Shamsuddin, A.H.; Sopian, K.

2000-01-01

Results of experimental investigations of fluidized bed combustion of palm oil wastes consisting of shell, fibre and empty fruit bunches high heating value of 17450 kJ/kg and low heating value of 14500 kJ/kg. The fluidized bed combuster used has a vessel size of 486 x 10 6 mm 3 , surface area of evaporation tubes and distribution air pipes of 500 mm 2 and 320 mm 2 respectively. It was found that a fuel feeding rate 160 kg/h is required to achieve a steam flow rate of 600 kg/h, with the combustion efficiency 96% and boiler efficiency of 72%, emission level of flue gas NO x at less than 180 ppm, SO 2 at less than 20 ppm are measured in the flue gas. (Author)

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.

Particle behavior and char burnout mechanisms under pressurized combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Bauer, C.M.; Spliethoff, H.; Hein, K.R.G.

1999-07-01

Combined cycle systems with coal-fired gas turbines promise highest cycle efficiencies for this fuel. Pressurized pulverized coal combustion, in particular, yields high cycle efficiencies due to the high flue gas temperatures possible. The main problem, however, is to ensure a flue gas clean enough to meet the high gas turbine standards with a dirty fuel like coal. On the one hand, a profound knowledge of the basic chemical and physical processes during fuel conversion under elevated pressures is required whereas on the other hand suitable hot gas cleaning systems need to be developed. The objective of this work was to provide experimental data to enable a detailed description of pressurized coal combustion processes. A series of experiments were performed with two German hvb coals, Ensdorf and Goettelborn, and one German brown coal, Garzweiler, using a semi-technical scale pressurized entrained flow reactor. The parameters varied in the experiments were pressure, gas temperature and bulk gas oxygen concentration. A two-color pyrometer was used for in-situ determination of particle surface temperatures and particle sizes. Flue gas composition was measured and solid residue samples taken and subsequently analyzed. The char burnout reaction rates were determinated varying the parameters pressure, gas temperature and initial oxygen concentration. Variation of residence time was achieved by taking the samples at different points along the reaction zone. The most influential parameters on char burnout reaction rates were found to be oxygen partial pressure and fuel volatile content. With increasing pressure the burn-out reactions are accelerated and are mostly controlled by product desorption and pore diffusion being the limiting processes. The char burnout process is enhanced by a higher fuel volatile content.

FY1996 annual report on the advanced combustion science in microgravity field

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Research was implemented continuously from the previous year on combustion equipment enabling advanced combustion technologies, by studying combustion in a microgravity field, for the purpose of preventing environmental pollution caused by diversification of energy sources and exhaust gasses. In joint studies with NASA, the themes of the previous year were continued, for which tests were conducted 37 times using Japanese drop test equipment and 131 times using NASA's. The evaluation and analysis of the experiments and test data by the microgravity test equipment were, in addition to the themes of the previous year, such that micro observation for ignition/combustion mechanism of fuel spray droplets was made, as well as studies on fuel droplets combustion by a laser diagnostic device, concerning combustion of fuel droplets and vaporization process, that flame spread on solid substances was researched in relation to combustion characteristics of high density fuels, and that mixed gas combustion on a solid surface was studied in connection with the research on flammability limits. Furthermore, a study on combustion technology for gas turbines was added for the purpose of studying an advanced combustor. (NEDO)

Chemical looping combustion. Fuel conversion with inherent CO2 capture

Energy Technology Data Exchange (ETDEWEB)

Brandvoll, Oeyvind

2005-07-01

Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO2 capture. In CLC, fuel combustion is split into separate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and fuel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a variant of oxy-fuel combustion. In principle, pure CO2 can be obtained from the reduction exhaust by condensation of the produced water vapour. The thermodynamic potential and feasibility of CLC has been studied by means of process simulations and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most important process parameters in CLC. A promising thermodynamic potential of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO2 capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiAl) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmospheric pressure and temperatures above 600 deg C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yielding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long-term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidation. The results for Ni

Effect of the reaction medium on the properties of solid catalysts

Energy Technology Data Exchange (ETDEWEB)

Boreskov, G.K.

1980-01-01

The effect of the reaction medium on the properties of solid catalysts, such as bulk or supported metals, alloys, or metal oxides, include variations in surface composition, structure, and catalytic properties due to catalyst interaction with the reactants. This interaction leads to the establishment of a steady state, which is determined by the composition of the reaction medium and temperature, but is independent of the initial state of the catalyst. This steady state for a catalyst of a given chemical composition is characterized by an approximately constant specific activity in most chemical reactions, which is almost independent of the preparation method, surface area, or crystal size of the catalyst. The structurally sensitive reactions, which occur only on limited segments of catalyst surface characterized by specific structures, are the exception. The effects of the variations in catalytic properties caused by the reaction medium on the steady-state and nonsteady-state reaction kinetics are also discussed based on the results obtained for oxidative dehydrogenation of 1-butene over an iron/antimony oxide catalyst.

Alcohol combustion chemistry

KAUST Repository

Sarathy, Mani

2014-10-01

Alternative transportation fuels, preferably from renewable sources, include alcohols with up to five or even more carbon atoms. They are considered promising because they can be derived from biological matter via established and new processes. In addition, many of their physical-chemical properties are compatible with the requirements of modern engines, which make them attractive either as replacements for fossil fuels or as fuel additives. Indeed, alcohol fuels have been used since the early years of automobile production, particularly in Brazil, where ethanol has a long history of use as an automobile fuel. Recently, increasing attention has been paid to the use of non-petroleum-based fuels made from biological sources, including alcohols (predominantly ethanol), as important liquid biofuels. Today, the ethanol fuel that is offered in the market is mainly made from sugar cane or corn. Its production as a first-generation biofuel, especially in North America, has been associated with publicly discussed drawbacks, such as reduction in the food supply, need for fertilization, extensive water usage, and other ecological concerns. More environmentally friendly processes are being considered to produce alcohols from inedible plants or plant parts on wasteland. While biofuel production and its use (especially ethanol and biodiesel) in internal combustion engines have been the focus of several recent reviews, a dedicated overview and summary of research on alcohol combustion chemistry is still lacking. Besides ethanol, many linear and branched members of the alcohol family, from methanol to hexanols, have been studied, with a particular emphasis on butanols. These fuels and their combustion properties, including their ignition, flame propagation, and extinction characteristics, their pyrolysis and oxidation reactions, and their potential to produce pollutant emissions have been intensively investigated in dedicated experiments on the laboratory and the engine scale

Synthesis by the Pechini method and reaction combustion for the preparation of TiO{sub 2}: a comparative analysis; Sintese pelo metodo Pechini e reacao de combustao para preparacao de TiO{sub 2}: uma analise comparativa

Energy Technology Data Exchange (ETDEWEB)

Almeida, E.P.; Ribeiro, P.C.; Freitas, N.L.; Lira, H.L.; Costa, A.C.F.M. da [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

2009-07-01

The aim of this work is to prepare TiO{sub 2} powder by Pechini and combustion reaction methods. A comparative analysis between the structural and morphological results obtained by the two methods was investigated. The powders were characterized by X-ray diffractions (XRD), infrared analysis, nitrogen adsorption (BET) and particle size distribution. The results from XRD show that the powders prepared by Pechini method and by combustion reaction using aniline as fuel, present anatase as major phase and traces of rutile phase. The values of crystallite size and surface area from BET were: 30 e 44 nm; 6.2 e 4.4 m{sup 2}/g, for the powders prepared by Pechini and combustion reaction, respectively. The values of particle size were: 21.9 e 5.3 {mu}m, for the powders prepared by Pechini and combustion reaction, respectively. The Pechini method was more suitable to obtain powders with irregular agglomerates, in the block shape with particles bonded softly and small crystallite size. (author)

Effects of Processing Parameters on the Fabrication of in-situ Al/TiC Composites by Thermally Activated Combustion Reaction Process in an Aluminium Melt using Al-TiO_2-C Powder Mixtures

International Nuclear Information System (INIS)

Kim, Hwa-Jung; Lee, Jung-Moo; Cho, Young-Hee; Kim, Jong-Jin; Kim, Su-Hyeon; Lee, Jae-Chul

2012-01-01

A feasible way to fabricate in-situ Al/TiC composites was investigated. An elemental mixture of Al-TiO_2-C pellet was directly added into an Al melt at 800-920°C to form TiC by self-combustion reaction. The addition of CuO initiates the self-combustion reaction to form TiC in 1-2 um at the melt temperature above 850°C. Besides the CuO addition, a diluent element of excess Al plays a significant role in the TiC formation by forming a precursor phase, Al_3Ti. Processing parameters such as CuO content, the amount of excess Al and the melt temperature, have affected the combustion reaction and formation of TiC, and their influences on the microstructures of in-situ Al/TiC composites are examined.

Straw combustion on slow-moving grates

DEFF Research Database (Denmark)

Kær, Søren Knudsen

2005-01-01

Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking......-column’’ approach and includes the energy equations for both the fuel and the gas accounting for heat transfer between the two phases. The model gives important insight into the combustion process and provides inlet conditions for a computational fluid dynamics analysis of the freeboard. The model predictions...... indicate the existence of two distinct combustion modes. Combustion air temperature and mass flow-rate are the two parameters determining the mode. There is a significant difference in reaction rates (ignition velocity) and temperature levels between the two modes. Model predictions were compared...

CFD modeling of combustion processes using KIVA3V Code with partially stirred reactor model for turbulence-combustion interactions

International Nuclear Information System (INIS)

Jarnicki, R.; Sobiesiak, A.

2002-01-01

In order to solve the averaged conservation equations for turbulent reacting flow one is faced with a task of specifying the averaged chemical reaction rate. This is due to turbulence influence on the mean reaction rates that appear in the species concentration Reynolds-averaged equation. In order to investigate the Partially Stirred Reactor (PaSR) combustion model capabilities, a CFD modeling using KIVA3V Code with the PaSR model of two very different combustion processes, was performed. Experimental results were compared with modeling

TEM investigations of microstructures of combustion aerosols

International Nuclear Information System (INIS)

Marquardt, A.; Hackfort, H.; Borchardt, J.; Schober, T.; Friedrich, J.

1992-12-01

In the incineration of organic material, apart from a series of gaseous pollutants, particulate pollutants or combustion aerosols also arise. The latter frequently consist of particles with a solid core of carbon to which a large number of inorganic and organic compounds are attached. These primarily include the polycyclic aromatic hydrocarbons (PAH) and their nitro-derivatives (NPAH), whose mutagenic or carcinogenic effect is known. The invisible particle sizes in the nanometer range, whose retention in the incineration off-gas is not state of the art, are of increasing significance for man and environment. On the one hand, they are deposited almost completely in the human lung. On the other hand, due to their fine dispersity they have along residence time in the atmosphere where they participate in chemical reactions and climatically significant processes. Important insights about the formation process of combustion aerosols are to be expected from the imaging of their microstructures in the transmission electron microscope (TEM). The present contribution describes the development and application of a representative sampling procedure for aerosols from a partial flow of flue gas from a fluidized-bed furnace. The method developed consists of electrically charging aerosol particles in situ and subsequently selectively precipitating them onto a microscope slide in an electric field. TEM studies of aerosol microstructures on the microscope slides revealed that in the combustion of petrol and heating oil under different combustion conditions in principle the same particle structures result, whereas in the incineration of used lubricating oil quite different particle structures were found. Results from the literature on aerosol microstructures in exhaust gases from petrol and diesel engines demonstrate agreement with the results of this study in the basic structure of the particles. (orig.) [de

Application of Fly Ash from Solid Fuel Combustion in Concrete

DEFF Research Database (Denmark)

Pedersen, Kim Hougaard

2008-01-01

with implementation of low-NOx combustion technologies. The present thesis concerns three areas of importance within this field: 1) testing of fly ash adsorption behavior; 2) the influence of fuel type and combustion conditions on the ash adsorption behaviour including full-scale experiments at the power plant...... has a low sensitivity toward small variations in AEA adsorption between different fly ashes and it requires further work before a finished procedure is accomplished. Finally, it was shown that changes in temperature affect both test methods. Pulverized fuel has been combusted in an entrained flow...... formation. It was found that the AEA adsorption of the fly ash was reduced up to five times compared to reference operation, when the plant was operated with minimum furnace air staging, three levels of burners instead of four and without recycled flue gas. The lower AEA requirements of the fly ash...

In Situ Monitoring of Chemical Reactions at a Solid-Water Interface by Femtosecond Acoustics.

Science.gov (United States)

Shen, Chih-Chiang; Weng, Meng-Yu; Sheu, Jinn-Kong; Yao, Yi-Ting; Sun, Chi-Kuang

2017-11-02

Chemical reactions at a solid-liquid interface are of fundamental importance. Interfacial chemical reactions occur not only at the very interface but also in the subsurface area, while existing monitoring techniques either provide limited spatial resolution or are applicable only for the outmost atomic layer. Here, with the aid of the time-domain analysis with femtosecond acoustics, we demonstrate a subatomic-level-resolution technique to longitudinally monitor chemical reactions at solid-water interfaces, capable of in situ monitoring even the subsurface area under atmospheric conditions. Our work was proven by monitoring the already-known anode oxidation process occurring during photoelectrochemical water splitting. Furthermore, whenever the oxide layer thickness equals an integer  number of the effective atomic layer thickness, the measured acoustic echo will show higher signal-to-noise ratios with reduced speckle noise, indicating the quantum-like behavior of this coherent-phonon-based technique.

Kinetics of in situ combustion. SUPRI TR 91

Energy Technology Data Exchange (ETDEWEB)

Mamora, D.D.; Ramey, H.J. Jr.; Brigham, W.E.; Castanier, L.M.

1993-07-01

Oxidation kinetic experiments with various crude oil types show two reaction peaks at about 250{degree}C (482{degree}F) and 400{degree}C (725{degree}F). These experiments lead to the conclusion that the fuel during high temperature oxidation is an oxygenated hydrocarbon. A new oxidation reaction model has been developed which includes two partially-overlapping reactions: namely, low-temperature oxidation followed by high-temperature oxidation. For the fuel oxidation reaction, the new model includes the effects of sand grain size and the atomic hydrogen-carbon (H/C) and oxygen-carbon (O/C) ratios of the fuel. Results based on the new model are in good agreement with the experimental data. Methods have been developed to calculate the atomic H/C and O/C ratios. These methods consider the oxygen in the oxygenated fuel, and enable a direct comparison of the atomic H/C ratios obtained from kinetic and combustion tube experiments. The finding that the fuel in kinetic tube experiments is an oxygenated hydrocarbon indicates that oxidation reactions are different in kinetic and combustion tube experiments. A new experimental technique or method of analysis will be required to obtain kinetic parameters for oxidation reactions encountered in combustion tube experiments and field operations.

Investigation of pressurized combustion and characterization of solid fuels

Energy Technology Data Exchange (ETDEWEB)

Aho, M; Haemaelaeinen, J; Paakkinen, K [VTT Energy, Espoo (Finland); Joutsenoja, T [Tampere Univ. of Technology (Finland)

1997-10-01

The objective of the research of Technical Research Centre of Finland (VTT) was to produce results of the effects of pressure and other important parameters on the combustion of pulverized coals using both experimental and theoretical methods. The results can be utilized to model pressurized combustion and to plan pilot-scale reactors. The studied coals were Polish hvb coal, French lignite (Gardanne), German anthracite (Niederberg) and German (Goettelborn) hvb coal. In was originally planned to study also a char of one of these coals. However, anthracite was selected instead of char, because the theoretical studies predicted maximum pressure effect to be found for antracite-type coals (with low reactivity and low content of volatiles). The pulverized coal samples were combusted in an electrically heated, pressurized entrained flow reactor (PEFR), where the experimental conditions were controlled with a high precision. The studied particle size fractions were 100-125 Em and 140-180 Am for anthracite and 140-180 {mu}m for the other coals. The studied things were combustion rates and temperatures of burning particles. Two types of sets of experiments were carried out. In the first case, experimental planning was done and the results were handled with multivariable partial least squares (PLS) method. Gas temperature varied from 1073K to 1473K and pressure from 0.2 MPa to 0.8 MPa. The other variables were PO2 and PCO{sub 2}. Some of the experiments were carried out at conditions prevailing during flue gas recirculation (CO{sub 2} concentration was > 20 vol%). In the second case, oxygen concentration was kept constant ( 10 vol%) and pressure was varied from 0.2 MPa to 0.8 MPa with an interval of 0.1 MPa

Study of reaction sequences for formation of solid solution: 0,48 ...

African Journals Online (AJOL)

... of a low concentration of ions forming the perovskite structure PZT (Pb2+, Zr4+ et Ti4+) by other ions (Zn2+, Cr3+ et Sb+5 in our study) alters the reaction sequences training of the solid solution PZT and especially the formation of intermediate phase. Keywords: PZT / Calcination / TGA / DTA / RX / Piezoelectric Ceramics ...

A model for steady-state HNF combustion

Energy Technology Data Exchange (ETDEWEB)

Louwers, J.; Gadiot, G.M.H.J.L. [TNO Prins Maurits Lab., Rijswijk (Netherlands); Brewster, M.Q. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States)

1997-09-01

A simple model for the combustion of solid monopropellants is presented. The condensed phase is treated by high activation energy asymptotics. The gas phase is treated by two limit cases: high activation energy, and low activation energy. This results in simplification of the gas phase energy equation, making an (approximate) analytical solution possible. The results of the model are compared with experimental results of Hydrazinium Nitroformate (HNF) combustion.

Factors affecting the amounts of emissions arising from fluidized bed combustion of solid fuels

International Nuclear Information System (INIS)

Horbaj, P.

1996-01-01

The factors affecting the amounts of nitrogen oxides (NO x ) and sulfur oxides (SO x , i.e. SO 2 + SO 3 ) formed during fluidized bed combustion of fossil fuels are analyzed using both theoretical concepts and experimental data. The factors treated include temperature, excess air, fuel parameters, pressure, degree of combustion gas recycling, combustion distribution along the combustion chamber height, and sulfur trapping processes for NO x , and the Ca/S ratio, fluidized layer height and fluidization rate, granulometry and absorbent type, fluidized layer temperature, and pressure during combustion for SO x . It is concluded that fluidized bed boilers are promising power generating facilities, mitigating the environmental burden arising from fossil fuel combustion. (P.A.). 12 figs., 9 refs

Analysis of the fuel influence in obtaining HAp by combustion reaction; Analise da influencia do combustivel na obtencao de HAp via reacao de combustao

Energy Technology Data Exchange (ETDEWEB)

Santos, T.L.; Leite, A.M.D.; Viana, K.M.S., E-mail: kalineviana@ect.ufrn.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Escola de Ciencias e Tecnologia

2016-07-01

The search for new materials for biomedical applications has led to investigation of the calcium phosphate bioceramics, and in particular hydroxyapatite (HAp), being a material similar to bone tissue, with excellent biocompatibility and high osteoconduction, enabling bone regeneration which allows the use at implants and prostheses. The synthesis of the nanometric HAp by combustion reaction enables obtaining the nanometric HAp with a more similar structure biological apatite as possible. This work aims to synthesize HAp by combustion reaction using two different routes of synthesis, first, using urea as fuel and the second using glycine, after this, evaluate the influence of fuels used in the microstructure of the hydroxyapatite obtained. The HAp obtained was characterized by: XRD, FTIR and SEM. Through analysis of the results, there is the synthesis conditions used that glycine has performed more favorable to obtaining HAp. (author)

Synthesis of Ca_3CO_4O_9 via solid state reaction

International Nuclear Information System (INIS)

Melo, K.P.; Dutra, R.P.S.; Marques, K.A.; Junior, S.M.S.; Brasileiro, C.T.; Coutinho, S.V.C.R.; Souza, T.; Chagas, T.F.; Silva, R.M.; Macedo, D.A.

2016-01-01

Solid oxide fuel cells (SOFCs) stand out as the most promising today's energy conversion technologies. In the development of cathode materials for SOFC, calcium cobaltate (Ca3Co4O9, C349) appears as a potential alternative to traditional lanthanum manganites. In this work, C349 was prepared via solid state reaction of stoichiometric mixtures containing CaCO3 from mollusk shells, in natura (M1) and heat treated at 550 ° C (M2), and Co3O4 obtained by citrate method. The M1 and M2 mixtures were calcined at 800 (powder) and 900 ° C (tablets) for 12 h. The crystal structure and phase composition of the powder and the reaction products were studied by X-ray diffraction Rietveld refinement of the diffraction data. The results showed the formation of free C349 secondary stages, showing a good alternative to use waste from seafood shells as raw material for obtaining high-value ceramics.(author)

FY 1994 annual report. Advanced combustion science utilizing microgravity

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-10-01

Researches on combustion in microgravity were conducted to develop combustion devices for advanced combustion techniques, and thereby to cope with the requirements for diversification of energy sources and abatement of environmental pollution by exhaust gases. This project was implemented under the research cooperation agreement with US's NASA, and the Japanese experts visited NASA's test facilities. NASA's Lewis Research Center has drop test facilities, of which the 2.2-sec drop test facilities are useful for researches by Japan. The cooperative research themes for combustion in microgravity selected include interactions between fuel droplets, high-pressure combustion of binary fuel sprays, and ignition and subsequent flame propagation in microgravity. An ignition test equipment, density field measurement equipment and flame propagation test equipment were constructed in Japan to conduct the combustion tests in microgravity for, e.g., combustion and evaporation of fuel droplets, combustion characteristics of liquid fuels mixed with solid particles, combustion of coal/oil mixture droplets, and estimating flammability limits. (NEDO)

Effects of air jet duration and timing on the combustion characteristics of high-pressure air jet controlled compression ignition combustion mode in a hybrid pneumatic engine

International Nuclear Information System (INIS)

Long, Wuqiang; Meng, Xiangyu; Tian, Jiangping; Tian, Hua; Cui, Jingchen; Feng, Liyan

2016-01-01

Highlights: • A 3-D CFD model of the power cylinder in HPE was developed. • High-pressure air JCCI combustion mode includes two-stage high-temperature reaction. • The combustion phasing of the pre-mixture is controllable via the SOJ timing. • There exists an optimum SOJ timing for obtaining the highest combustion efficiency and shortest burning duration. - Abstract: The high-pressure air jet controlled compression ignition (JCCI) combustion mode was employed to control the premixed diesel compression ignition combustion phasing by using the compound thermodynamic cycle under all operating conditions, which is accomplished in a hybrid pneumatic engine (HPE). A three-dimensional computational fluid dynamics (CFD) numerical simulation coupled with reduced n-heptane chemical kinetics mechanism has been applied to investigate the effects of high-pressure air jet duration and the start of jet (SOJ) timing on the combustion characteristics in the power cylinder of HPE. By sweeping the high-pressure air jet durations from 6 to 14 °CA and SOJ timings from −12 °CA ATDC to the top dead center (TDC) under the air jet temperatures of 400 and 500 K, respectively, the low- and high-temperature reactions, combustion efficiency, as well as the combustion phasing and burning duration have been analyzed in detail. The results illustrated that a longer air jet duration results in a higher peak in the first-stage high-temperature reaction, and the short air jet duration of 6 °CA can lead to a higher combustion efficiency. The SOJ timing sweep results showed that there exists an optimum timing for obtaining the highest combustion efficiency and shortest burning duration.

Ammonium nitrate: combustion mechanism and the role of additives

Energy Technology Data Exchange (ETDEWEB)

Sinditskii, Valery P.; Egorshev, Viacheslav Yu.; Levshenkov, Anton I.; Serushkin, Valery V. [Department of Chemical Engineering, Mendeleev University of Chemical Technology, 9 Miusskaya Sq., 125047, Moscow (Russian Federation)

2005-09-01

This paper presents an analysis of the observed combustion behavior of AN mixtures with different additives, fuels, and energetic materials. It has been determined on the basis of flame structure investigation by fine tungsten-rhenium thermocouples that the surface temperature of AN is controlled by the dissociation reaction of the salt occurring at the surface. Results obtained have indicated that the leading reaction of combustion of AN doped with additives proceeds in the condensed phase up to pressures of 20-30 MPa. A reason for the inability of pure AN to burn is suggested and the role of additives in the combustion mechanism is discussed. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

In situ synthesis and formation mechanism of ZrC and ZrB2 by combustion synthesis from the Co-Zr-B4C system

Directory of Open Access Journals (Sweden)

Mengxian Zhang

2015-09-01

Full Text Available ZrC-ZrB2-based composites were prepared by combustion synthesis (CS reaction from 10 wt.% to 50 wt.% Co-Zr-B4C powder mixtures. With increasing Co contents, the particle sizes of near-spherical ZrC and platelet-like ZrB2 decreased from 1 μm to 0.5 μm and from 5 μm to 2 μm, respectively. In addition, the formation mechanism of ZrC and ZrB2 was explored by the phase transition and microstructure evolution on the combustion wave quenched sample in combination with differential scanning calorimeter analysis. The results showed that the production of ZrC was ascribed to the solid-solid reaction between Zr and C and the precipitation from the Co-Zr-B-C melt, while ZrB2 was prepared from the saturated liquid. The low B concentration in the Co-Zr-B-C liquid and high cooling rate during the CS process led to the presence of Co2B and ZrCo3B2 in the composites. The addition of Co in the Co-Zr-B4C system not only prevented ZrC and ZrB2 particulates from growing, but also promoted the occurrence of ZrC-ZrB2-forming reaction.

Flow and Combustion in Advanced Gas Turbine Combustors

CERN Document Server

Janicka, Johannes; Schäfer, Michael; Heeger, Christof

2013-01-01

With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts.

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

International Nuclear Information System (INIS)

Ogawa, Makoto; Morita, Masashi; Igarashi, Shota; Sato, Soh

2013-01-01

A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst

Combustion synthesis of TiC-based materials: Mechanisms, densification, and properties

International Nuclear Information System (INIS)

LaSalvia, J.C.; Meyers, M.A.

1995-01-01

The micromechanisms involved in the combustion synthesis of a Ti-C-Ni-Mo mixture resulting in the formation of a TiC-based composite were examined using the combustion wave quenching technique developed by Rogachev et al. At the micron level, the main reaction occurs at the interface between a Ti-Ni-C melt and C particles, resulting in the formation of a solid TiC x layer on the C particles. This layer undergoes a successive process of rapid growth and decomposition into TiC x spherules until all of the C particle is consumed. This mechanism is consistent with the apparent activation energy (E = 100 kJ/mol) for the process obtained from a macrokinetic investigation of the system. The apparent uniformity in size (d = 1 μm) of the TiC x spherules upon formation indicates a critical condition in the stability of the energetics involved in the process. These TiC x spherules undergo growth due to Ostwald ripening and coalescence mechanisms resulting in a final apparent size of 2.5 μm. For the compositions investigated, the addition of Mo did not affect either the micromechanisms or macrokinetics of the combustion synthesis process. Densification of the porous body after the combustion synthesis process can be carried out while it is still in a easily deformable state. The highly porous body is densified by a combination of fracture (communition), plastic deformation, and sintering. The mechanisms are identified for the case of combustion synthesized TiC. Mechanical properties and microstructures of a number of materials (e.g. TiC, TiB 2 , Al 2 O 3 -TiB 2 , TiB 2 -SiC, TiC-Ni-Mo) produced by combustion synthesis combined with a high-velocity forging step are reviewed

Solid-state nuclear magnetic resonance studies of phosphorus and boron in coals and combustion residues

Energy Technology Data Exchange (ETDEWEB)

Burchill, P.; Howarth, O.W.; Richards, D.G.; Sword, B.J. (British Coal Corporation, Stoke Orchard (UK). Coal Research Establishment)

1990-04-01

Solid-state nuclear magnetic resonance spectroscopy with magic angle spinning (MAS-n.m.r.) was used to study the occurrence of phosphorus and boron in coal, and their fate on combustion. These elements are only minor components of coal, but may significantly influence the utilization properties. {sup 31} P MAS-n.m.r. spectroscopy has confirmed that phosphorus is present in coal predominantly as apatite. This mineral is thermally stable under oxidizing conditions, and survives largely unaltered in high temperature ashes. However, under the semi-reducing bed conditions of certain stoker-fired boilers, it may be decomposed, volatilizing the phosphorus. The {sup 31}P MAS-n.m.r. spectra of bonded deposits show phosphorus in a markedly different coordination environment to that in apatite, the chemical shift suggesting aluminium phosphate or boron phosphate. {sup 11}B MAS-n.m.r. spectra of coals exhibit resonances due to both trigonal and tetrahedrally coordinated boron. Trigonal boron is probably present as tourmaline, but the nature of the tetrahedral boron is less certain; it may be held in tetrahedral sites within certain clay minerals. In common with phosphorus, boron may be volatilized during combustion. The {sup 11}B MAS-n.m.r. spectra of bonded deposits show a tetrahedral resonance with a chemical shift quite consistent with that of boron phosphate. 39 refs., 9 figs., 5 tabs.

The Use of Silver Solid Amalgam Electrodes for Voltammetric and Amperometric Determination of Nitrated Polyaromatic Compounds Used as Markers of Incomplete Combustion

Directory of Open Access Journals (Sweden)

Oksana Yosypchuk

2012-01-01

Full Text Available Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE, which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10−7 mol L−1 concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L−1 phosphate buffer, pH 7.0 : methanol (15 : 85, v/v mobile phase, and C18 reversed stationary phase. Limits of detection of around 1 · 10−5 mol L−1 were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10−6 mol L−1.

Synthesis NiAl1,0Fe1,0O4 catalyst by the combustion reaction to their use in the shift reaction (WGSR)

International Nuclear Information System (INIS)

Santos, P.T.A.; Costa, A.C.F.M.; Neiva, L.S.; Gama, L.; Argolo, F.; Andrade, H.M.C.

2009-01-01

This work aims at the synthesis of catalyst NiAl 1,0 Fe 1,0 O 4 by combustion reaction using urea as fuel, to evaluate its performance in the production of hydrogen by the reaction of displacement of water vapor (WGSR). The initial composition of the solution was based on valencia total oxidizing and reducing reagents based on the concepts of the chemistry of propellants, using container as a crucible of glassy silica. The resulting powder was characterized by X-ray diffraction, infrared spectroscopy, nitrogen adsorption isotherms (BET), scanning electronic microscope and catalytic tests. The DRX results reveal the presents majoritary phase NiAl 1,0 Fe 1,0 O 4 spinel, the catalyst presents surface area 28 m 2 /g and isotherms type III. Higher conversion CO/CO 2 of 75% CO conversion observed at 500 deg C and catalytic activity of 43 mmolg -1 .h -1 at 450 deg C. (author)

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.

Internal and surface phenomena in metal combustion

Science.gov (United States)

Dreizin, Edward L.; Molodetsky, Irina E.; Law, Chung K.

1995-01-01

Combustion of metals has been widely studied in the past, primarily because of their high oxidation enthalpies. A general understanding of metal combustion has been developed based on the recognition of the existence of both vapor-phase and surface reactions and involvement of the reaction products in the ensuing heterogeneous combustion. However, distinct features often observed in metal particle combustion, such as brightness oscillations and jumps (spearpoints), disruptive burning, and non-symmetric flames are not currently understood. Recent metal combustion experiments using uniform high-temperature metal droplets produced by a novel micro-arc technique have indicated that oxygen dissolves in the interior of burning particles of certain metals and that the subsequent transformations of the metal-oxygen solutions into stoichiometric oxides are accompanied with sufficient heat release to cause observed brightness and temperature jumps. Similar oxygen dissolution has been observed in recent experiments on bulk iron combustion but has not been associated with such dramatic effects. This research addresses heterogeneous metal droplet combustion, specifically focusing on oxygen penetration into the burning metal droplets, and its influence on the metal combustion rate, temperature history, and disruptive burning. A unique feature of the experimental approach is the combination of the microgravity environment with a novel micro-arc Generator of Monodispersed Metal Droplets (GEMMED), ensuring repeatable formation and ignition of uniform metal droplets with controllable initial temperature and velocity. The droplet initial temperatures can be adjusted within a wide range from just above the metal melting point, which provides means to ignite droplets instantly upon entering an oxygen containing environment. Initial droplet velocity will be set equal to zero allowing one to organize metal combustion microgravity experiments in a fashion similar to usual microgravity

Understanding Combustion Processes Through Microgravity Research

Science.gov (United States)

Ronney, Paul D.

1998-01-01

A review of research on the effects of gravity on combustion processes is presented, with an emphasis on a discussion of the ways in which reduced-gravity experiments and modeling has led to new understanding. Comparison of time scales shows that the removal of buoyancy-induced convection leads to manifestations of other transport mechanisms, notably radiative heat transfer and diffusional processes such as Lewis number effects. Examples from premixed-gas combustion, non-premixed gas-jet flames, droplet combustion, flame spread over solid and liquid fuels, and other fields are presented. Promising directions for new research are outlined, the most important of which is suggested to be radiative reabsorption effects in weakly burning flames.

Combustion of a Pb(II)-loaded olive tree pruning used as biosorbent

Energy Technology Data Exchange (ETDEWEB)

Ronda, A., E-mail: alirg@ugr.es [Department of Chemical Engineering, University of Granada, 18071 Granada (Spain); Della Zassa, M. [Department of Industrial Engineering, University of Padua, 35131 Padova (Italy); Martín-Lara, M.A.; Calero, M. [Department of Chemical Engineering, University of Granada, 18071 Granada (Spain); Canu, P. [Department of Industrial Engineering, University of Padua, 35131 Padova (Italy)

2016-05-05

Highlights: • The fate of Pb during combustion at two scales of investigation was studied. • Results from combustion in a flow reactor and in the thermobalance were consistent. • The Pb contained in the solid remained in the ashes. • The Pb does not interfere in the use of OTP as fuel. • The combustion of Pb(II)-loaded OTP does not cause environmental hazards. - Abstract: The olive tree pruning is a specific agroindustrial waste that can be successfully used as adsorbent, to remove Pb(II) from contaminated wastewater. Its final incineration has been studied in a thermobalance and in a laboratory flow reactor. The study aims at evaluating the fate of Pb during combustion, at two different scales of investigation. The flow reactor can treat samples approximately 10{sup 2} larger than the conventional TGA. A detailed characterization of the raw and Pb(II)-loaded waste, before and after combustion is presented, including analysis of gas and solids products. The Pb(II)-loaded olive tree pruning has been prepared by a previous biosorption step in a lead solution, reaching a concentration of lead of 2.3 wt%. Several characterizations of the ashes and the mass balances proved that after the combustion, all the lead presents in the waste remained in ashes. Combustion in a flow reactor produced results consistent with those obtained in the thermobalance. It is thus confirmed that the combustion of Pb(II)-loaded olive tree pruning is a viable option to use it after the biosorption process. The Pb contained in the solid remained in the ashes, preventing possible environmental hazards.

Transfer of heat to fluidized-solids beds

Energy Technology Data Exchange (ETDEWEB)

1952-10-16

The improvement in the method described and claimed in patent application 14,363/47 (136,186) for supplying heat to a dense turbulent mass of solid fluidized by a gas flowing upwardly therethrough and subjected to a high temperature in a treating zone, by heat transfer through heat-transfer surfaces of heat-transfer elements in contact with the said turbulent mass of finely divided solid and heated by means of a fluid heating medium, including burning fuels comprising contacting the said heat-transfer surfaces with a fuel and a combustion supporting gas under such conditions that the combustion of the fuel is localized in the heat-transfer element near the point of entry of the fuel and combustion-supporting gas and a substantial temperature gradient is maintained along the path of said fuel combustion-supporting gas and combustion products through the said heat-transfer element.

Influence of the external heating type in the morphological and structural characteristics of alumina powder prepared by combustion reaction

International Nuclear Information System (INIS)

Cordeiro, V.V.; Freitas, N.L.; Viana, K.M.S.; Dias, G.; Costa, A.C.F.M.; Lira, H.L.

2009-01-01

The aim of this work is to evaluate the influence of the external heating in the morphological and structural characteristics of the alumina powder prepared by combustion reaction. It was evaluated different types of external heating: muffle oven, microwave oven and ceramic plate with electrical spiral resistance. The powders were prepared according to the propellants and explosives theory, using urea in the stoichiometric proportion (Φe = 1). During the synthesis parameters such as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluate by XRD, particle size distribution, SEM and nitrogen adsorption (BET). The results showed the production of a-alumina as unique phase and formed by agglomerates with irregular plate shape of thin particles for all studied conditions. The powders prepared by electrical oven presented small particle size, with narrow agglomerates size distribution. (author)

Behavior of heavy metals during fluidized bed combustion of poultry litter

OpenAIRE

Lynch, Deirdre; Low, Fiona; Henihan, Anne Marie; Garcia, Alberto; Kwapinski, Witold; Zhang, Lian; Leahy, J.J.

2014-01-01

peer-reviewed In this study, we have examined the behavior of heavy metals during fluidized bed combustion of poultry litter. Heavy metals examined include As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V, and Zn. Solid and gaseous streams were analyzed and compared with relevant guidelines to determine the potential environmental impact of combustion and subsequent land spreading or landfill of the resulting ash. The majority of heavy metals were associated with the solid ash fraction, with low ...

Low-temperature synthesis of actinide tetraborides by solid-state metathesis reactions

Science.gov (United States)

Lupinetti, Anthony J [Los Alamos, NM; Garcia, Eduardo [Los Alamos, NM; Abney, Kent D [Los Alamos, NM

2004-12-14

The synthesis of actinide tetraborides including uranium tetraboride (UB.sub.4), plutonium tetraboride (PuB.sub.4) and thorium tetraboride (ThB.sub.4) by a solid-state metathesis reaction are demonstrated. The present method significantly lowers the temperature required to .ltoreq.850.degree. C. As an example, when UCl.sub.4 is reacted with an excess of MgB.sub.2, at 850.degree. C., crystalline UB.sub.4 is formed. Powder X-ray diffraction and ICP-AES data support the reduction of UCl.sub.3 as the initial step in the reaction. The UB.sub.4 product is purified by washing water and drying.

High Gravity (g) Combustion

Science.gov (United States)

2006-02-01

UNICORN (Unsteady Ignition and Combustion with Reactions) code10. Flame propagation in a tube that is 50-mm wide and 1000-mm long (similar to that...turbine engine manufacturers, estimating the primary zone space heating rate. Both combustion systems, from Company A and Company B, required a much...MBTU/atm-hr-ft3) Te m pe ra tu re R is e (K ) dP/P = 2% dP/P = 2.5% dP/P = 3% dP/P = 3.5% dP/P = 4% Company A Company B Figure 13: Heat Release Rate

A new combustion route to γ-Fe2O3 synthesis

Indian Academy of Sciences (India)

A new combustion route for the synthesis of -Fe2O3 is reported by employing purified -Fe2O3 as aprecursor in the present investigation. This synthesis which is similar to a self propagation combustion reaction, involves fewer steps, a shorter overall processing time, is a low energy reaction without the need of any ...

Occurrence of bromine in fluidised bed combustion of solid recovered fuel

Energy Technology Data Exchange (ETDEWEB)

Vainikka, P.

2011-12-15

Corrosive ash species are the single most important factor limiting the electric efficiency of steam boiler plants fired with waste or biomass. Chlorine has been found to have a central role in the chemistry involved as it reduces the melting temperature of ash, forms corrosive vapour and gas species in the furnace and halogenated deposits on boiler heat transfer surfaces. In this context chlorine has been extensively researched. At the time of writing this thesis there was hardly any published data available on the occurrence of bromine (Br) in the aforementioned context. The objective of this work was to review the occurrence of bromine in solid fuels and characterise the behaviour of bromine in full-scale fluidised bed combustion. The review on the occurrence of bromine in solid fuels revealed that in anthropogenic wastes bromine is mainly found in connection to flame retarded substances. Several weight percentages of bromine can be found in plastics treated with brominated flame retardants (BFRs). Bromine is typically found some 100-200 mg kg-1 in mixed municipal solid wastes (MSW). Bromine may be enriched in fuels with high share of plastics, such as solid recovered fuel (SRF) or refuse derived fuel (RDF). Up to 2000 mg kg-1 was found as a monthly average in SRF, typical levels being 20-200 mg kg-1. Wastewater sludge from paper mills may contain bromine 20-100 mg kg-1 due the use of bromine based biocides. In other fuels bromine may be found in significant amounts in marine influenced coal deposits and peat as well as in biomass treated with brominated pesticides. In the experimental part SRF, spruce bark and wastewater sludge from a paper mill were co-fired in a full- scale bubbling fluidised bed (BFB) boiler, and the collected fuels, aerosols and waterwall deposits were analysed with the focus on the fate of bromine. Bromine was mainly found to form water soluble high vapour pressure alkali metal halides in the furnace - in the form of KBr(g) and NaBr(g) as

Combustion Joining of Regolith Tiles for In-Situ Fabrication of Launch/Landing Pads on the Moon and Mars

Science.gov (United States)

Ferguson, Robert E.; Shafirovich, Evgeny; Mantovani, James G.

2017-01-01

To mitigate dust problems during launch/landing operations in lunar and Mars missions, it is desired to build solid pads on the surface. Recently, strong tiles have been fabricated from lunar regolith simulants using high-temperature sintering. The present work investigates combustion joining of these tiles through the use of exothermic intermetallic reactions. Specifically, nickel/aluminum (1:1 mole ratio) mixture was placed in a gap between the tiles sintered from JSC-1A lunar regolith simulant. Upon ignition by a laser, a self-sustained propagation of the combustion front over the mixture occurred. Joining was improved with increasing the tile thickness from 6.3 mm to 12.7 mm. The temperatures sufficient for melting the glass phase of JSC-1A were recorded for 12.7-mm tiles, which explains the observed better joining.

Suppression of the Thermal Decomposition Reaction of Forest Combustible Materials in Large-Area Fires

Science.gov (United States)

Volkov, R. S.; Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.

2018-05-01

Experimental investigations on the characteristic time of suppression of the thermal decomposition reaction of typical forest combustible materials (aspen twigs, birch leaves, spruce needles, pine chips, and a mixture of these materials) and the volume of water required for this purpose have been performed for model fire hotbeds of different areas: SFCM = 0.0003-0.007 m2 and SFCM = 0.045-0.245 m2. In the experiments, aerosol water flows with droplets of size 0.01-0.25 mm were used for the spraying of model fire hotbeds, and the density of spraying was 0.02 L/(m2·s). It was established that the characteristics of suppression of a fire by an aerosol water flow are mainly determined by the sizes of the droplets in this flow. Prognostic estimates of changes in the dispersivity of a droplet cloud, formed from large (as large as 0.5 L) "drops" (water agglomerates) thrown down from a height, have been made. It is shown that these changes can influence the conditions and characteristics of suppression of a forest fire. Dependences, allowing one to forecast the characteristics of suppression of the thermal decomposition of forest combustible materials with the use of large water agglomerates thrown down from an aircraft and aerosol clouds formed from these agglomerates in the process of their movement to the earth, are presented.

Suppression of the Thermal Decomposition Reaction of Forest Combustible Materials in Large-Area Fires

Science.gov (United States)

Volkov, R. S.; Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.

2018-03-01

Experimental investigations on the characteristic time of suppression of the thermal decomposition reaction of typical forest combustible materials (aspen twigs, birch leaves, spruce needles, pine chips, and a mixture of these materials) and the volume of water required for this purpose have been performed for model fire hotbeds of different areas: SFCM = 0.0003-0.007 m2 and SFCM = 0.045-0.245 m2. In the experiments, aerosol water flows with droplets of size 0.01-0.25 mm were used for the spraying of model fire hotbeds, and the density of spraying was 0.02 L/(m2·s). It was established that the characteristics of suppression of a fire by an aerosol water flow are mainly determined by the sizes of the droplets in this flow. Prognostic estimates of changes in the dispersivity of a droplet cloud, formed from large (as large as 0.5 L) "drops" (water agglomerates) thrown down from a height, have been made. It is shown that these changes can influence the conditions and characteristics of suppression of a forest fire. Dependences, allowing one to forecast the characteristics of suppression of the thermal decomposition of forest combustible materials with the use of large water agglomerates thrown down from an aircraft and aerosol clouds formed from these agglomerates in the process of their movement to the earth, are presented.

Co-combustion of anthracite coal and wood pellets: Thermodynamic analysis, combustion efficiency, pollutant emissions and ash slagging.

Science.gov (United States)

Guo, Feihong; Zhong, Zhaoping

2018-08-01

This work presents studies on the co-combustion of anthracite coal and wood pellets in fluidized bed. Prior to the fluidized bed combustion, thermogravimetric analysis are performed to investigate the thermodynamic behavior of coal and wood pellets. The results show that the thermal decomposition of blends is divided into four stages. The co-firing of coal and wood pellets can promote the combustion reaction and reduce the emission of gaseous pollutants, such as SO 2 and NO. It is important to choose the proportion of wood pellets during co-combustion due to the low combustion efficiency caused by large pellets with poor fluidization. Wood pellets can inhibit the volatilization of trace elements, especially for Cr, Ni and V. In addition, the slagging ratio of wood pellets ash is reduced by co-firing with coal. The research on combustion of coal and wood pellets is of great significance in engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

Room temperature ferromagnetism in Eu-doped ZnO nanoparticulate powders prepared by combustion reaction method

International Nuclear Information System (INIS)

Franco, A.; Pessoni, H.V.S.; Soares, M.P.

2014-01-01

Nanoparticulate powders of Eu-doped ZnO with 1.0, 1.5, 2.0 and 3.0 at% Eu were synthesized by combustion reaction method using zinc nitrate, europium nitrate and urea as fuel without subsequent heat treatments. X-ray diffraction patterns (XRD) of all samples showed broad peaks consistent with the ZnO wurtzite structure. The absence of extra reflections in the diffraction patterns ensures the phase purity, except for x=0.03 that exhibits small reflection corresponding to Eu 2 O 3 phase. The average crystallite size determined from the most prominent (1 0 1) peak of the diffraction using Scherrer's equation was in good agreement with those determined by transmission electron microscopy (TEM); being ∼26 nm. The magnetic properties measurements were performed using a vibrating sample magnetometer (VSM) in magnetic fields up to 2.0 kOe at room temperature. The hysteresis loops, typical of magnetic behaviors, indicating that the presence of an ordered magnetic structure can exist in the Eu-doped ZnO wurtzite structure at room temperature. The room temperature ferromagnetism behavior increases with the Eu 3+ doping concentration. All samples exhibited the same Curie temperature (T C ) around ∼726 K, except for x=0.01; T C ∼643 K. High resolution transmission electron microscopy (HRTEM) images revealed defects/strain in the lattice and grain boundaries of Eu-doped ZnO nanoparticulate powders. The origin of room temperature ferromagnetism in Eu-doped ZnO nanoparticulate powders was discussed in terms of these defects, which increase with the Eu 3+ doping concentration. - Highlights: • Room-temperature ferromagnetism. • Structural and magnetic properties of nanoparticulate powders of Zn 1−x Eu x O. • Combustion reaction method

Computational modeling of chemical reactions and interstitial growth and remodeling involving charged solutes and solid-bound molecules.

Science.gov (United States)

Ateshian, Gerard A; Nims, Robert J; Maas, Steve; Weiss, Jeffrey A

2014-10-01

Mechanobiological processes are rooted in mechanics and chemistry, and such processes may be modeled in a framework that couples their governing equations starting from fundamental principles. In many biological applications, the reactants and products of chemical reactions may be electrically charged, and these charge effects may produce driving forces and constraints that significantly influence outcomes. In this study, a novel formulation and computational implementation are presented for modeling chemical reactions in biological tissues that involve charged solutes and solid-bound molecules within a deformable porous hydrated solid matrix, coupling mechanics with chemistry while accounting for electric charges. The deposition or removal of solid-bound molecules contributes to the growth and remodeling of the solid matrix; in particular, volumetric growth may be driven by Donnan osmotic swelling, resulting from charged molecular species fixed to the solid matrix. This formulation incorporates the state of strain as a state variable in the production rate of chemical reactions, explicitly tying chemistry with mechanics for the purpose of modeling mechanobiology. To achieve these objectives, this treatment identifies the specific theoretical and computational challenges faced in modeling complex systems of interacting neutral and charged constituents while accommodating any number of simultaneous reactions where reactants and products may be modeled explicitly or implicitly. Several finite element verification problems are shown to agree with closed-form analytical solutions. An illustrative tissue engineering analysis demonstrates tissue growth and swelling resulting from the deposition of chondroitin sulfate, a charged solid-bound molecular species. This implementation is released in the open-source program FEBio ( www.febio.org ). The availability of this framework may be particularly beneficial to optimizing tissue engineering culture systems by examining the

Growth behavior of LiMn{sub 2}O{sub 4} particles formed by solid-state reactions in air and water vapor

Energy Technology Data Exchange (ETDEWEB)

Kozawa, Takahiro, E-mail: t-kozawa@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yanagisawa, Kazumichi [Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, 2–5-1 Akebono-cho, Kochi 780-8520 (Japan); Murakami, Takeshi; Naito, Makio [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2016-11-15

Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn{sub 2}O{sub 4} particles in air and water vapor atmospheres as model reactions; LiMn{sub 2}O{sub 4} is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO{sub 3} precursor impregnated with LiOH, LiMn{sub 2}O{sub 4} spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn{sub 2}O{sub 4} particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

Simulation of biodiesel combustion in a light-duty diesel engine using integrated compact biodiesel–diesel reaction mechanism

DEFF Research Database (Denmark)

Ng, Hoon Kiat; Gan, Suyin; Ng, Jo-Han

2013-01-01

This computational fluid dynamics (CFD) study is performed to investigate the combustion characteristics and emissions formation processes of biodiesel fuels in a light-duty diesel engine. A compact reaction mechanism with 80 species and 303 reactions is used to account for the effects of chemical...... kinetics. Here, the mechanism is capable of emulating biodiesel–diesel mixture of different blending levels and biodiesel produced from different feedstock. The integrated CFD-kinetic model was validated against a test matrix which covers the entire saturated–unsaturated methyl ester range typical...... of biodiesel fuels, as well as the biodiesel–diesel blending levels. The simulated cases were then validated for in-cylinder pressure profiles and peak pressure values/timings. Errors in the peak pressure values did not exceed 1%, while the variations in peak pressure timings were kept within 1.5 crank angle...

Tetragonal-cubic phase boundary in nanocrystalline ZrO2-Y2O3 solid solutions synthesized by gel-combustion

International Nuclear Information System (INIS)

Fabregas, Ismael O.; Craievich, Aldo F.; Fantini, Marcia C.A.; Millen, Ricardo P.; Temperini, Marcia L.A.; Lamas, Diego G.

2011-01-01

Research highlights: → Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO 2 -Y 2 O 3 nanopowders, that exhibit the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms (t' and t'') and the cubic phase. → Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. → The crystallographic features of ZrO 2 -Y 2 O 3 nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. → Compositional t'/t'' and t''/cubic phase boundaries are located at (9 ± 1) and (10.5 ± 0.5) mol% Y 2 O 3 , respectively. → For the whole series of nanocrystalline ZrO 2 -Y 2 O 3 solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO 2 -Y 2 O 3 solid solutions, the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO 2 -Y 2 O 3 solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro

Hybrid Approach for Modeling Chemical Kinetics and Turbulence Effects on Combustion-Instability, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Combustion instabilities pose a significant technical risk in the development of liquid and solid rocket motors. Much of the effort in modeling combustion...

Wood products in the waste stream: Characterization and combustion emissions. Volume 1. Final report

International Nuclear Information System (INIS)

1992-11-01

Waste wood is wood separated from the solid-waste stream and processed into a uniform-sized product that is reused for other purposes such as fuel. As an alternative to the combustion of fossil fuels, it has raised concerns that if it is 'contaminated' with paints, resins, preservatives, etc., unacceptable environmental impacts may be generated during combustion. Given the difficulty of separating contaminated materials from waste wood and the large energy potential existing in the resource, it is important to identify possible problems associated with contaminated waste wood combustion. The study describes research about technical, public policy, and regulatory issues that affect the processing and combustion of waste wood for fuel. The project's purpose was to provide environmental regulators, project developers, and others with data to make informed decisions on the use of waste wood materials as a combustion resource. Potential environmental problems and solutions were identified. A specific project result was the identification of combustion system operation parameters and air pollution control technologies that can minimize emissions of identified air and solid waste contaminants from combustion of wood waste

Ab initio Thermodynamic Approach to Identify Mixed Solid Sorbents for CO2 Capture Technology

Directory of Open Access Journals (Sweden)

Yuhua eDuan

2015-10-01

Full Text Available Because the current technologies for capturing CO2 are still too energy intensive, new materials must be developed that can capture CO2 reversibly with acceptable energy costs. At a given CO2 pressure, the turnover temperature (Tt of the reaction of an individual solid that can capture CO2 is fixed. Such Tt may be outside the operating temperature range (ΔTo for a practical capture technology. To adjust Tt to fit the practical ΔTo, in this study, three scenarios of mixing schemes are explored by combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations. Our calculated results demonstrate that by mixing different types of solids, it’s possible to shift Tt to the range of practical operating temperature conditions. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO2 capture reactions by the mixed solids of interest, we were able to identify the mixing ratios of two or more solids to form new sorbent materials for which lower capture energy costs are expected at the desired pressure and temperature conditions.

Update on status of fluidized-bed combustion technology

International Nuclear Information System (INIS)

Stallings, J.; Boyd, T.; Brown, R.

1992-01-01

During the 1980s, fluidized-bed combustion technology has become the dominant technology for solid-fuel-fired power generation systems in the United States. Atmospheric fluidized beds as large as 160 MWe in capacity are now in operation, while pressurized systems reaching 80 MWe have started up in the last year. The commercial status, boiler performance, emissions, and future developments for both atmospheric and pressurized fluidized-bed combustion systems are discussed

Quantum Chemical Study of Supercritical Carbon Dioxide Effects on Combustion Kinetics.

Science.gov (United States)

Masunov, Artëm E; Wait, Elizabeth E; Atlanov, Arseniy A; Vasu, Subith S

2017-05-18

In oxy-fuel combustion, the pure oxygen (O 2 ), diluted with CO 2 is used as oxidant instead air. Hence, the combustion products (CO 2 and H 2 O) are free from pollution by nitrogen oxides. Moreover, high pressures result in the near-liquid density of CO 2 at supercritical state (sCO 2 ). Unfortunately, the effects of sCO 2 on the combustion kinetics are far from being understood. To assist in this understanding, in this work we are using quantum chemistry methods. Here we investigate potential energy surfaces of important combustion reactions in the presence of the carbon dioxide molecule. All transition states and reactant and product complexes are reported for three reactions: H 2 CO + HO 2 → HCO + H 2 O 2 (R1), 2HO 2 → H 2 O 2 + O 2 (R2), and CO + OH → CO 2 + H (R3). In reaction R3, covalent binding of CO 2 to the OH radical and then the CO molecule opens a new pathway, including hydrogen transfer from oxygen to carbon atoms followed by CH bond dissociation. Compared to the bimolecular OH + CO mechanism, this pathway reduces the activation barrier by 5 kcal/mol and is expected to accelerate the reaction. In the case of hydroperoxyl self-reaction 2HO 2 → H 2 O 2 + O 2 the intermediates, containing covalent bonds to CO 2 are found not to be competitive. However, the spectator CO 2 molecule can stabilize the cyclic transition state and lower the barrier by 3 kcal/mol. Formation of covalent intermediates is also discovered in the H 2 CO + HO 2 → HCO + H 2 O 2 reaction, but these species lead to substantially higher activation barriers, which makes them unlikely to play a role in hydrogen transfer kinetics. The van der Waals complexation with carbon dioxide also stabilizes the transition state and reduces the reaction barrier. These results indicate that the CO 2 environment is likely to have a catalytic effect on combustion reactions, which needs to be included in kinetic combustion mechanisms in supercritical CO 2 .

Method for reactivating solid catalysts used in alkylation reactions

Science.gov (United States)

Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

2003-06-17

A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

Supersonic Combustion of Hydrogen Jets System in Hypersonic Stream

International Nuclear Information System (INIS)

Zhapbasbaev, U.K.; Makashev, E.P.

2003-01-01

The data of calculated theoretical investigations of diffusive combustion of plane supersonic hydrogen jets in hypersonic stream received with Navier-Stokes parabola equations closed by one-para metrical (k-l) model of turbulence and multiply staged mechanism of hydrogen oxidation are given. Combustion mechanisms depending on the operating parameters are discussing. The influences of air stream composition and ways off fuel feed to the length of ignition delay and level quantity of hydrogen bum-out have been defined. The calculated theoretical results of investigations permit to make the next conclusions: 1. The diffusive combustion of the system of plane supersonic hydrogen jets in hypersonic flow happens in the cellular structures with alternation zones of intensive running of chemical reactions with their inhibition zones. 2. Gas dynamic and heat Mach waves cause a large - scale viscous formation intensifying mixing of fuel with oxidizer. 3. The system ignition of plane supersonic hydrogen jets in hypersonic airy co-flow happens with the formation of normal flame front of hydrogen airy mixture with transition to the diffusive combustion. 4. The presence of active particles in the flow composition initiates the ignition of hydrogen - airy mixture, provides the intensive running of chemical reactions and shortens the length of ignition delay. 5. The supersonic combustion of hydrogel-airy mixture is characterized by two zones: the intensive chemical reactions with an active energy heat release is occurring in the first zone and in the second - a slow hydrogen combustion limited by the mixing of fuel with oxidizer. (author)

Numerical simulation code for combustion of sodium liquid droplet and its verification

International Nuclear Information System (INIS)

Okano, Yasushi

1997-11-01

The computer programs for sodium leak and burning phenomena had been developed based on mechanistic approach. Direct numerical simulation code for sodium liquid droplet burning had been developed for numerical analysis of droplet combustion in forced convection air flow. Distributions of heat generation and temperature and reaction rate of chemical productions, such as sodium oxide and hydroxide, are calculated and evaluated with using this numerical code. Extended MAC method coupled with a higher-order upwind scheme had been used for combustion simulation of methane-air mixture. In the numerical simulation code for combustion of sodium liquid droplet, chemical reaction model of sodium was connected with the extended MAC method. Combustion of single sodium liquid droplet was simulated in this report for the verification of developed numerical simulation code. The changes of burning rate and reaction product with droplet diameter and inlet wind velocity were investigated. These calculation results were qualitatively and quantitatively conformed to the experimental and calculation observations in combustion engineering. It was confirmed that the numerical simulation code was available for the calculation of sodium liquid droplet burning. (author)

Volatiles from solids

Energy Technology Data Exchange (ETDEWEB)

Loughrey, C T

1939-08-24

To remove volatiles from solids, such as oil shale, gases, and/or vapours are passed through a mass of the materials, the vapours and gases separated, and the vapours condensed. The volatile-containing solid materials are fed to a retort, and a shaft is driven to rotate an impeller so as to displace the liquid and create a vortex tube, which draws in gas from the atmosphere through an intake, twyer, interstices in the material in the retort, a conduit, chamber, tubes, another chamber and cylinder. This gas is carried outwardly and upwardly by the vortices in the liquid and is carried to discharge through three conduits. The vapours entrained by the gas are part condensed in the liquid and the remainder directed to a condenser. Steam may be delivered to the twyer through a nozzle of a pipe, with or without air, and combustible hydrocarbon fuel may be fed through the burner nozzle or solid fuel may be directed from feeder and combusted in the twyer.

3rd International Conference on Numerical Combustion

CERN Document Server

Larrouturou, Bernard; Numerical Combustion

1989-01-01

Interest in numerical combustion is growing among applied mathematicians, physicists, chemists, engine manufacturers and many industrialists. This proceedings volume contains nine invited lectures and twenty seven contributions carefully selected by the editors. The major themes are numerical simulation of transsonic and supersonic combustion phenomena, the study of supersonic reacting mixing layers, and turbulent combustion. Emphasis is laid on hyperbolic models and on numerical simulations of hydrocarbon planes with a complete set of chemical reactions carried out in two-dimensional geometries as well as on complex reactive flow simulations.

Emission of nanoparticles during combustion of waste biomass in fireplace

Science.gov (United States)

Drastichová, Vendula; Krpec, Kamil; Horák, Jiří; Hopan, František; Kubesa, Petr; Martiník, Lubomír; Koloničný, Jan; Ochodek, Tadeáš; Holubčík, Michal

2014-08-01

Contamination of air by solid particles is serious problem for human health and also environment. Small particles in nano-sizes are more dangerous than same weight of larger size. Negative effect namely of the solid particles depends on (i) number, (ii) specific surface area (iii) respirability and (iv) bonding of others substances (e.g. PAHs, As, Cd, Zn, Cu etc.) which are higher for smaller (nano-sizes) particles compared to larger one. For this reason mentioned above this contribution deals with measuring of amount, and distribution of nanoparticles produced form combustion of waste city biomass in small combustion unit with impactor DLPI.

Solid biomass barometer

International Nuclear Information System (INIS)

Anon.

2007-01-01

Primary energy production from solid biomass (wood, wood waste and other solid vegetal and animal materials) reached 62,4 million tons oil equivalent (Mtoe) in 2006, i-e 3,1 more than in 2005. The primary energy coming from the direct combustion of renewable origin solid urban waste in incineration unit scan also be added to this figure. In 2006 this represented a production of 5,3 Mtoe, i-e 0,1 Mtoe more than in 2005. (author)

Computational Modeling of Mixed Solids for CO2 CaptureSorbents

Energy Technology Data Exchange (ETDEWEB)

Duan, Yuhua

2015-01-01

Since current technologies for capturing CO2 to fight global climate change are still too energy intensive, there is a critical need for development of new materials that can capture CO2 reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO2 capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO2 sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO2 adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO2 capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. Only those selected CO2 sorbent candidates were further considered for experimental validations. The ab initio thermodynamic technique has the advantage of identifying thermodynamic properties of CO2 capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. Such methodology not only can be used to search for good candidates from existing database of solid materials, but also can provide some guidelines for synthesis new materials. In this presentation, we apply our screening methodology to mixing solid systems to adjust the turnover temperature to help on developing CO2 capture Technologies.

Introduction to Physics and Chemistry of Combustion Explosion, Flame, Detonation

CERN Document Server

Liberman, Michael A

2008-01-01

Most of the material covered in this book deals with the fundamentals of chemistry and physics of key processes and fundamental mechanisms for various combustion and combustion related phenomena in gaseous combustible mixture. It provides the reader with basic knowledge of burning processes and mechanisms of reaction wave propagation. The combustion of a gas mixture (flame, explosion, detonation) is necessarily accompanied by motion of the gas. The process of combustion is therefore not only a chemical phenomenon but also one of gas dynamics. The material selection focuses on the gas phase and

Nitrogen evolution during the co-combustion of hydrothermally treated municipal solid waste and coal in a bubbling fluidized bed.

Science.gov (United States)

Lu, Liang; Jin, Yuqi; Liu, Hongmei; Ma, Xiaojun; Yoshikawa, Kunio

2014-01-01

Nitrogen evolution was studied during the co-combustion of hydrothermally treated municipal solid wastes (HT MSW) and coal in a bubbling fluidized bed (BFB). HT MSW blending ratios as 10%, 20% and 30% (wt.%) were selected and tested at 700, 800, 900 °C. Emissions of NO and N2O from blends were measured and compared with the results of mono-combustion trials. Moreover, concentrations of precursors like NH3 and HCN were also quantified. The results are summarized as follows: NO emissions were predominant in all the cases, which rose with increasing temperature. The blending of HT MSW contributed to the NO reduction. N2O emissions decreased with temperature rising and the blending of HT MSW also presented positive effects. At 30% HT MSW addition, both NO and N2O emissions showed the lowest values (391.85 ppm and 55.33 ppm, respectively at 900 °C). For the precursors, more HCN was detected than NH3 and both played important roles on the gas side nitrogen evolution. Copyright © 2013. Published by Elsevier Ltd.

Advances in Turbulent Combustion Dynamics Simulations in Bluff-Body Stabilized Flames-Body Stabilized Flames

Science.gov (United States)

2015-11-30

during combustion for GRI -Mech 1.2 reaction mechanism using LEM and CHEMKIN. . . . . . . . . . . . . . . . 34 3.7 Comparison of temperature during...combustion for GRI -Mech 1.2 raction mechanism using LEM and CHEMKIN. . . . . . . . . . . . . . . . . . . . . 34 3.8 The methane profile along the 5 mm long...combustion process was tested using GRI -Mech 1.2 [44]. GRI -Mech is an optimized detailed chemical reaction mechanism capable of the best representation of

Numerical study of radiation effect on the municipal solid waste combustion characteristics inside an incinerator

Energy Technology Data Exchange (ETDEWEB)

Wang, Jingfu, E-mail: jfwang@bjut.edu.cn; Xue, Yanqing; Zhang, Xinxin; Shu, Xinran

2015-10-15

Highlights: • A 3-D model for the MSW incinerator with preheated air was developed. • Gas radiative properties were obtained from a statistical narrow-band model. • Non-gray body radiation model can provide more accurate simulation results. - Abstract: Due to its advantages of high degree volume reduction, relatively stable residue, and energy reclamation, incineration becomes one of the best choices for Municipal Solid Waste (MSW) disposal. However, detailed measurements of temperature and gas species inside a furnace are difficulty by conventional experimental techniques. Therefore, numerical simulation of MSW incineration in the packed bed and gas flow field was applied. In this work, a three dimensional (3-D) model of incinerator system, including flow, heat transfer, detailed chemical mechanisms, and non-gray gas models, was developed. Radiation from the furnace wall and the flame formed above the bed is of importance for drying and igniting the waste. The preheated air with high temperature is used for the MSW combustion. Under the conditions of high temperature and high pressure, MSW combustion produces a variety of radiating gases. The wavelength-depend radiative properties of flame adopted in non-gray radiation model were obtained from a statistical narrow-band model. The influence of radiative heat transfer on temperature, flow field is researched by adiabatic model (without considering radiation), gray radiation model, and non-gray radiation model. The simulation results show that taking into account the non-gray radiation is essential.

Comparative analysis of synthesis and characterization of La_0_,_9Sr_0_,_1O_3 via sol-gel and combustion reaction

International Nuclear Information System (INIS)

Tarrago, D.P.; Haeser, G.S.; Malfatti, C.F.; Sousa, V.C.

2011-01-01

Strontium doped lanthanum manganites (LSM) are potential materials for cathode application in solid oxide fuel cells (SOFC) due to their properties and compatibility with yttria stabilized zirconia. In this work a LSM powder obtained by the sol-gel process is compared others previously obtained combustion synthesis using urea or sucrose as fuel. For the synthesis of LSM the nitrates of lanthanum, strontium and manganese were dissolved in citric acid and ethylene glycol forming a gel that was calcinated at 800 deg C. Both methods allowed the synthesis of a single phase powder, according to the X-ray diffraction patterns. Through gas adsorption it was found a specific surface area of 17m²/g, an intermediary value among the combustion synthesized powders. Scanning electron microscopy (SEM) revealed more compact agglomerates in the sol-gel powder, however, the transmission electron microscope (TEM) showed smaller and more uniform particles in this powder. (author)

Consideration on standard substance for the conbustion test of oxidizing solid. Sankasei kotai no nensho shiken no kijun busshitsu ni kansuru kosatsu

Energy Technology Data Exchange (ETDEWEB)

Muranaga, K [The Japan Carlit Co. Ltd., Tokyo (Japan); Tamura, M; Yoshida, T [The University of Tokyo, Tokyo (Japan). Faculty of Engineering

1991-04-15

The mixture of KClO {sub 3} and wood flour is the standard substance in the combustion test by the Fire Service Law to investigate the accelerating combustion of an oxidizing agent, but it is difficult to measure the combustion time owing to the intermittent combustion. This paper described the study to get any compounds superior to the above mentioned. Since the mixture of KNO {sub 3}-wood flour combusts more rapidly than that of KClO {sub 3}-wood flour, a new mixture of similar combustion rate to that of the mixture of KClO {sub 3} and wood flour and without intermittent combustion was tried to get by adding an inactive solid powder to decrease the combustion rate. But a new mixture which has the combustion time of about 4 minutes, shows uniform combustion instead of intermittent combustion and shows the only slight variation of combustion time, could not be found. It is because of intermittent combustion that the mixture of KClO {sub 3} and wood flour can endure the combustion for 4 minutes although this mixture has larger reaction heat. The combustion time of this mixture is shortened if the igniting nichrome wire temperature exceeds 1,000 centigrade. Further, the bulk density of deposit affects greatly the combustion time. 7 refs., 2 figs., 4 tabs.

Prediction of Non-Equilibrium Kinetics of Fuel-Rich Kerosene/LOX Combustion in Gas Generator

International Nuclear Information System (INIS)

Yu, Jung Min; Lee, Chang Jin

2007-01-01

Gas generator is the device to produce high enthalpy gases needed to drive turbo-pump system in liquid rocket engine. And, the combustion temperature in gas generator should be controlled below around 1,000K to avoid any possible thermal damages to turbine blade by using either fuel rich combustion or oxidizer rich combustion. Thus, nonequilibrium chemical reaction dominates in fuel-rich combustion of gas generator. Meanwhile, kerosene is a compounded fuel with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focuses on the prediction of the non-equilibrium reaction of fuel rich kerosene/LOX combustion with detailed kinetics developed by Dagaut using PSR (Perfectly Stirred Reactor) assumption. In Dagaut's surrogate model for kerosene, chemical kinetics of kerosene consists of 1,592 reaction steps with 207 chemical species. Also, droplet evaporation time is taken into account in the PSR calculation by changing the residence time of droplet in the gas generator. Frenklach's soot model was implemented along with detailed kinetics to calculate the gas properties of fuel rich combustion efflux. The results could provide very reliable and accurate numbers in the prediction of combustion gas temperature,species fraction and material properties

Combustion characteristics of SMX and SMX based propellants

Science.gov (United States)

Reese, David A.

This work investigates the combustion of the new solid nitrate ester 2,3-hydroxymethyl-2,3-dinitro-1,4-butanediol tetranitrate (SMX, C6H 8N6O16). SMX was synthesized for the first time in 2008. It has a melting point of 85 °C and oxygen balance of 0% to CO 2, allowing it to be used as an energetic additive or oxidizer in solid propellants. In addition to its neat combustion characteristics, this work also explores the use of SMX as a potential replacement for nitroglycerin (NG) in double base gun propellants and as a replacement for ammonium perchlorate in composite rocket propellants. The physical properties, sensitivity characteristics, and combustion behaviors of neat SMX were investigated. Its combustion is stable at pressures of up to at least 27.5 MPa (n = 0.81). The observed flame structure is nearly identical to that of other double base propellant ingredients, with a primary flame attached at the surface, a thick isothermal dark zone, and a luminous secondary flame wherein final recombination reactions occur. As a result, the burning rate and primary flame structure can be modeled using existing one-dimensional steady state techniques. A zero gas-phase activation energy approximation results in a good fit between modeled and observed behavior. Additionally, SMX was considered as a replacement for nitroglycerin in a double base propellant. Thermochemical calculations indicate improved performance when compared with the common double base propellant JA2 at SMX loadings above 40 wt-%. Also, since SMX is a room temperature solid, migration may be avoided. Like other nitrate esters, SMX is susceptible to decomposition over long-term storage due to the presence of excess acid in the crystals; the addition of stabilizers (e.g., derivatives of urea) during synthesis should be sufficient to prevent this. the addition of Both unplasticized and plasticized propellants were formulated. Thermal analysis of unplasticized propellant showed a distinct melt

Kinetic models for pyrolysis and combustion of sewage sludge[Held jointly with the 4. Canadian organic residuals and biosolids managment conference

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, R.; Udaquiola, S. [Univ. Nacional de San Juan, San Juan (Argentina). Lab. Tec. Amb., Inst. de Ing. Qca; Gauthier, D; Flamant, G. [PROMES-CNRS, Font-Romeu Odeillo (France); Mazza, G. [Univ. Nacional Del Comahue, Neuquen (Argentina). Dept. de Quimica; Martinez, O. [Univ. Nacional de la Plata, La Plata (Argentina). CINDECA-CONICET

2007-07-01

In thermochemical conversion processes that produce energy, the kinetics of waste decomposition must be considered. The rate of mass loss due to thermal decomposition determines the available fuel on the fire triangle of heat, fuel and oxygen. Heating rates in thermobalance experiments are low, and are often used to study the primary reactions in the decomposition of solids since their cracking is negligible. Thermogravimetry is an option for determining the decomposition profile of a solid in terms of its temperature versus the kinetics of its decomposition. This paper presented the thermal analysis and results of a study that used thermogravimetric analyses on dry samples of sewage sludge from San Juan, Argentina in an inert and oxidative atmosphere. Three peaks were observed in all differential thermogravimetric curves during the organic matter decomposition. In order to explain the experimental data, various reaction schemes were set up. The first two schemes considered 3 fractions decomposing in parallel during pyrolysis, with oxidative pyrolysis of all fractions during combustion or only two. The third scheme considered the decomposition of 2 fractions only but with dissymmetrical behavior during the whole pyrolysis and combustion phenomenon. It was concluded that the simulations were a good agreement with the experimental data for the first 2 schemes only, and overall, the fit was better with the second scheme. 11 refs., 4 figs.

Evaluation of different water-washing treatments effects on wheat straw combustion properties.

Science.gov (United States)

Ma, Qiulin; Han, Lujia; Huang, Guangqun

2017-12-01

A series of experiments was conducted to explore the effects of various water-washing solid-liquid ratios (1:50 and 1:10) and the stirring on wheat straw (WS) combustion properties. Comparing different solid-liquid ratio groups, a 16% increment in the higher heating value was obtained for 1:50 groups and only 5% for 1:10 groups relative to the raw material. Moreover, energy was lost 4-26 times greater in 1:10 groups than 1:50 groups. While water-washing reduced the comprehensive combustibility index by 14.89%-32.09%, the index values of washed WS were all higher than 2, indicating good combustion performance. The combustion activation energy of four washed WS were 175, 172, 186, and 176kJ/mol, which were all higher than the 160kJ/mol of WS. The fouling/slagging propensity of washed WS reduced to a lower possibility compared to medium of untreated WS. Overall, the recommended condition for washing WS before combustion is 1:50 ratio without stirring. Copyright © 2017. Published by Elsevier Ltd.

Behaviour, capture and inertization of some trace elements during combustion of refuse-derived char from municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Vassilev, S.V.; Braekman-Danheux, C.; Laurent, P.; Thiemann, T.; Fontana, A. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Lab. of Mineralogy and Crystallography

1999-08-01

An investigation of refuse-derived char (RDC) generated by thermolysis of municipal solid waste (MSW) was undertaken to elucidate the behaviour of some toxic and potentially toxic trace elements (Cr, Cu, Mn, Ni, Pb, Sb and Zn) plus Fe during combustion of RDC. About 87% of Sb, 66% of Pb, 60% of Cu and significant parts of Fe{gt}Zn{gt}Ni{gt}Mn{gt}Cr from the RDC are volatile at 1200{degree}C, and their behaviour in the temperature interval 500-1200{degree}C is characterized. The use of sorbents (zeolite, kaolinite, montmorillonite, coals enriched in kaolinite and calcite, and lime plus portlandite) for capture, solidification and inertization of the most volatile elements during combustion of RDC is also described. Perspective sorbents and inertants for a retention of the most volatile Pb, Sb and Cu in RDC ash are kaolinite and montmorillonite or coals enriched in these minerals. In addition, when there is an effective RDC washing (dechlorination and desulphurization), the use of sorbents for capture of some metals could be reduced or even avoided. Recommendations are given for RDC utilization and improvisation of the collection, separation procedures and removal efficiency of some heavy-metal, chloride and sulphate compounds from MSW and RDC prior to their use. The results show that a long-term strategy based on detailed understanding of the source, formation, behaviour and fate of the elements and their modes of occurrence in MSW, RDC and combustion waste residues is required in order to validate a perspective waste pyrolytic processes development. 55 refs., 3 figs., 6 tabs.

Combustion Stability Assessments of the Black Brant Solid Rocket Motor

Science.gov (United States)

Fischbach, Sean

2014-01-01

The Black Brant variation of the Standard Brant developed in the 1960's has been a workhorse motor of the NASA Sounding Rocket Project Office (SRPO) since the 1970's. In March 2012, the Black Brant Mk1 used on mission 36.277 experienced combustion instability during a flight at White Sands Missile Range, the third event in the last four years, the first occurring in November, 2009, the second in April 2010. After the 2010 event the program has been increasing the motor's throat diameter post-delivery with the goal of lowering the chamber pressure and increasing the margin against combustion instability. During the most recent combustion instability event, the vibrations exceeded the qualification levels for the Flight Termination System. The present study utilizes data generated from T-burner testing of multiple Black Brant propellants at the Naval Air Warfare Center at China Lake, to improve the combustion stability predictions for the Black Brant Mk1 and to generate new predictions for the Mk2. Three unique one dimensional (1-D) stability models were generated, representing distinct Black Brant flights, two of which experienced instabilities. The individual models allowed for comparison of stability characteristics between various nozzle configurations. A long standing "rule of thumb" states that increased stability margin is gained by increasing the throat diameter. In contradiction to this experience based rule, the analysis shows that little or no margin is gained from a larger throat diameter. The present analysis demonstrates competing effects resulting from an increased throat diameter accompanying a large response function. As is expected, more acoustic energy was expelled through the nozzle, but conversely more acoustic energy was generated due to larger gas velocities near the propellant surfaces.

Emission Modeling of an Interturbine Burner Based on Flameless Combustion

NARCIS (Netherlands)

Perpignan, A.A.V.; Talboom, M.G.; Levy, Yeshayahou; Gangoli Rao, A.

2018-01-01

Since its discovery, the flameless combustion (FC) regime has been a promising alternative to reduce pollutant emissions of gas turbine engines. This combustion mode is characterized by well-distributed reaction zones, which potentially decreases temperature gradients, acoustic oscillations, and

Computational Study of Stratified Combustion in an Optical Diesel Engine

KAUST Repository

Jaasim, Mohammed

2017-03-28

Full cycle simulations of KAUST optical diesel engine were conducted in order to provide insights into the details of fuel spray, mixing, and combustion characteristics at different start of injection (SOI) conditions. Although optical diagnostics provide valuable information, the high fidelity simulations with matched parametric conditions improve fundamental understanding of relevant physical and chemical processes by accessing additional observables such as the local mixture distribution, intermediate species concentrations, and detailed chemical reaction rates. Commercial software, CONVERGE™, was used as the main simulation tool, with the Reynolds averaged Navier-Stokes (RANS) turbulence model and the multi-zone (SAGE) combustion model to compute the chemical reaction terms. SOI is varied from late compression ignition (CI) to early partially premixed combustion (PPC) conditions. The simulation results revealed a stronger correlation between fuel injection timing and combustion phasing for late SOI conditions, whereas the combustion phasing starts to decouple from SOI for early SOI cases. The predictions are consistent with the experimental observations, in terms of the overall trends in combustion and emission characteristics, while the high fidelity simulations provided further insights into the effects of mixture stratifications resulting from different SOI conditions.

chemical kinetic study of nitrogen oxides formation in methane flameless combustion

International Nuclear Information System (INIS)

Alvarado T, Pedro N; Cadavid S, Francisco; Mondragon, P Fanor; Ruiz, Wilson

2009-01-01

The present paper deals with the nitrogen oxides formation in a flameless combustion process characterized for using air highly diluted and preheated at high temperatures. The combustion model used in this study was the one dimensional counterflow methane air diffusion flame. The NOx production rate analysis showed that the thermal and prompt mechanisms are the most important for the formation and consumption of NO under dilution conditions for the oxidant in N 2 and combustion products. These mechanisms are related since the starting reaction for NO formation (N2 molecular dissociation) belongs to the prompt mechanism while the NO formation is reported mainly for the thermal mechanism reactions. On the other hand, the NO - NO 2 equilibrium showed that the reaction rates are comparable to that obtained by the thermal and prompt mechanisms, but its global contribution to NO formation are almost insignificant due to the oxidation reaction with radicals HO 2 .

Ion-beam mixing and solid-state reaction in Zr-Fe multilayers

International Nuclear Information System (INIS)

Paesano, A. Jr.; Motta, A.T.; Birtcher, R.C.; Ryan, E.A.; Teixeira, S.R.; Bruckmann, M.E.; Amaral, L.

1997-01-01

Vapor-deposited Zr-Fe multilayered thin films with various wavelengths and of overall composition either 50% Fe or Fe-rich up to 57% Fe were either irradiated with 300 keV Kr ions at temperatures from 25 K to 623 K to fluences up to 2 x 10 16 cm -2 , or simply annealed at 773 K in-situ in the Intermediate Voltage Electron microscope At Argonne National Laboratory. Under irradiation, the final reaction product is the amorphous phase in all cases studied, but the dose to amorphization depends on the temperature and on the wavelength. In the purely thermal case (annealing at 773 K), the 50-50 composition produces the amorphous phase but for the Fe-rich multilayers the reaction products depend on the multilayer wavelength. For small wavelength, the amorphous phase is still formed, but at large wavelength the Zr-Fe crystalline intermetallic compounds appear. These results are discussed in terms of existing models of irradiation kinetics and phase selection during solid state reaction

A Computational Fluid Dynamics Study of Turbulence, Radiation, and Combustion Models for Natural Gas Combustion Burner

Directory of Open Access Journals (Sweden)

Yik Siang Pang

2018-01-01

Full Text Available This paper presents a Computational Fluid Dynamics (CFD study of a natural gas combustion burner focusing on the effect of combustion, thermal radiation and turbulence models on the temperature and chemical species concentration fields. The combustion was modelled using the finite rate/eddy dissipation (FR/EDM and partially premixed flame models. Detailed chemistry kinetics CHEMKIN GRI-MECH 3.0 consisting of 325 reactions was employed to model the methane combustion. Discrete ordinates (DO and spherical harmonics (P1 model were employed to predict the thermal radiation. The gas absorption coefficient dependence on the wavelength is resolved by the weighted-sum-of-gray-gases model (WSGGM. Turbulence flow was simulated using Reynolds-averaged Navier-Stokes (RANS based models. The findings showed that a combination of partially premixed flame, P1 and standard k-ε (SKE gave the most accurate prediction with an average deviation of around 7.8% of combustion temperature and 15.5% for reactant composition (methane and oxygen. The results show the multi-step chemistry in the partially premixed model is more accurate than the two-step FR/EDM. Meanwhile, inclusion of thermal radiation has a minor effect on the heat transfer and species concentration. SKE turbulence model yielded better prediction compared to the realizable k-ε (RKE and renormalized k-ε (RNG. The CFD simulation presented in this work may serve as a useful tool to evaluate a performance of a natural gas combustor. Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 9th October 2017; Accepted: 30th October 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Pang, Y.S., Law, W.P., Pung, K.Q., Gimbun, J. (2018. A Computational Fluid Dynamics Study of Turbulence, Radiation, and Combustion Models for Natural Gas Combustion Burner. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 155-169 (doi:10.9767/bcrec

Aspects chimiques de la combustion du charbon pulvérisé. Première partie Chemical Aspects of the Combustion of Pulverized Coal. Part One

Directory of Open Access Journals (Sweden)

De Soete G. G.

2006-11-01

an attempt to coherently describe the key chemical mechanisms which confront one another in such combustion. These mechanisms involve relatively fast gas-phase reactions (combustion of pyrolysis gas products, formation of nitrogen oxides from organic nitrogen as well as various extremely important heterogeneous reactions (fast pyrolyzing devolatilization, coke oxidation, heterogeneous reduction of nitrogen oxides which may occur much more slowly. With regard to these reactions, the non-isothermal regime caused by the existence of temperature gradients in an industrial flame often have non negligible consequences for the way in which such complex kinetic mechanisms proceed. For example, the amount and composition of the pyrolysis products depends to a considerable degree on these non-isothermal conditions. A coal flame is the crossroads for several complex chemical mechanisms. It is chemically characterized by a great many cases of competition : (a competition among different reaction paths inside a given mechanism, with a typical example being the pyrolysis of coal; (b competition among chemical and physical phenomena, also occurring inside the saine mechanism, causing an eventually reversible transition from a kinetic regime to a diffusional regime, as is the case in the oxidation of coke, with appreciable consequences on the overall reaction velocity and its dependence on temperature, even being able to go to the extinction of coke combustion; (c competition between two totally different mechanisms, e. g. between a homogeneous ignition mechanism and a heterogeneous ignition mechanism of coal, with practical consequences on the stabilization of an industrial flame. Another example is that of competition among different homogeneous mechanisms of nitrogen oxide formation and heterogeneous mechanisms of their reduction on solid coke particles, soot and ash. With these ideas presented as an implicit leitmotif , the major phases of an industrial pulverized coal flame are

Combustion synthesis and characterization of uranium and thorium tellurides

International Nuclear Information System (INIS)

Czechowicz, D.G.

1985-10-01

This report describes an investigation of the chemical systems uranium-tellurium and thorium-tellurium. A novel synthesis technique, combustion synthesis, which uses the exothermic heat of reaction rather than externally supplied heat, was utilized to form the phases UTe, U 3 Te 4 , and UTe 2 in the U-Te system and the phases ThTe, Th 2 Te 3 , and ThTe 2 in the Th-Te system from reactions of the type U/sub x/ + Te/sub y/ = U/sub x/Te/sub y/. With this synthetic method, U-Te and Th-Te products could be formed in a matter of seconds, and the purity of the products was often greater than that of the starting materials used. Control over final product stoichiometry was found to be very difficult. The product phase distribution observed in combustion products, as determined by x-ray diffraction, electron microprobe, and optical metallographic methods, was found to be spatially complex. Lattice constants were calculated from x-ray diffraction patterns for the compounds UTe, U 3 Te 4 , and ThTe. SOLGASMIX thermodynamic equilibrium calculations were performed using available and estimated thermodynamic data on the system U-Te-O in an attempt to understand the products formed by combustion. Adiabatic combustion reaction temperatures for specific U-Te and Th-Te reactions were also calculated utilizing available and estimated thermodynamic data. 71 refs., 31 figs., 15 tabs

Natural Ores as Oxygen Carriers in Chemical Looping Combustion

Energy Technology Data Exchange (ETDEWEB)

Tian, Hanjing; Siriwardane, Ranjani; Simonyi, Thomas; Poston, James

2013-08-01

Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

Study of the obtainment of Mo_2C by gas-solid reaction in a fixed and rotary bed reactor

International Nuclear Information System (INIS)

Araujo, C.P.B. de; Souza, C.P. de; Souto, M.V.M.; Barbosa, C.M.; Frota, A.V.V.M.

2016-01-01

Carbides' synthesis via gas-solid reaction overcomes many of the difficulties found in other processes, requiring lower temperatures and reaction times than traditional metallurgic routes, for example. In carbides' synthesis in fixed bed reactors (FB) the solid precursor is permeated by the reducing/carburizing gas stream forming a packed bed without mobility. The use of a rotary kiln reactor (RK) adds a mixing character to this process, changing its fluid-particle dynamics. In this work ammonium molybdate was subjected to carbo-reduction reaction (CH4 / H2) in both reactors under the same gas flow (15L / h) and temperature (660 ° C) for 180 minutes. Complete conversion was observed Mo2C (dp = 18.9nm modal particles sizes' distribution) in the fixed bed reactor. In the RK reactor this conversion was only partial (∼ 40%) and Mo2C and MoO3 (34nm dp = bimodal) could be observed on the produced XRD pattern. Partial conversion was attributed to the need to use higher solids loading in the reactor CR (50% higher) to avoid solids to centrifuge. (author)

Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; Dai, Sheng

2015-07-15

Here in this paper, we report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent-free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60–90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; Dai, Sheng

2015-07-15

Herein, we report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent-free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60–90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

Emission of nitrous oxide during combustion of organic fuels

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.; Gol' dberg, A.S.

1990-11-01

Analyzes formation of nitrogen oxides during combustion of coal, natural gas and mazout: chemical reactions that lead to formation of nitrous oxide during coal combustion, reaction kinetics and reaction yields, factors that influence emission of nitrogen oxides from a furnace, factors that influence formation of nitrous oxide (temperature effects, air excess ratio, coal burnout degree, etc.), effects of fuel type and its chemical composition, effects of flue gas desulfurization and denitrification methods on nitrous oxide yield. Analyses show that yield of nitrous oxide is low and does not exceed 5 cm{sup 3}/m{sup 3} flue gas (0.0005%). However chemical reactions of nitrogen oxides, sulfur dioxide and water vapor in the atmosphere are said to form additional quantities of nitrous oxide which negatively influence the ozone layer. 4 refs.