scholarly journals Combustion peculiarities of coal-methane-air mixtures in a recuperative burner

2018 ◽  
Vol 243 ◽  
pp. 00007
Author(s):  
Leonid Minkov ◽  
Kseniya Moiseeva
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Reaction Zone ◽  
Volatile Matter ◽  
Oxidation Reactions ◽  
Volatile Substances ◽  
Fine Coal ◽  
Coal Particles ◽  
Roll Type

Numerical modeling of the combustion of a lean methane-air mixture containing fine coal particles entering the “Swiss-roll” type recuperative burner is considered. The mathematical model is constructed under the following assumptions: the flow field is two-dimensional; the gas mixture is an ideal incompressible gas consisting of oxygen, methane, coal volatile substances, carbon monoxide, carbon dioxide, water vapor, hydrogen and nitrogen. In the gas phase four oxidation reactions, in which methane, volatile matter of coal, carbon monoxide, hydrogen participate and the reaction of carbon dioxide decomposition take place. On the surface of the coal particle, there are three oxidation reactions involving oxygen, carbon dioxide and water vapor, resulting in the formation of carbon monoxide. It is assumed that coal contains 8% of ash, 12.9% of volatile substances and 79.1% of carbon. It is shown that for a two percent methane-air mixture the reaction zone shifts toward the center of the burner as the feed rate of the mixture increases. An increase in the content of coal particles leads to a shift of the reaction zone into the inlet part of the burner, and the heat release in the burner increases.

ACTION OF HIGH SPEED ELECTRONS ON METHANE, OXYGEN AND CARBON MONOXIDE

1930 ◽  
Vol 3 (3) ◽  
pp. 241-251 ◽  
Author(s):  
J. C. McLennan F.R.S. ◽  
J. V. S. Glass B.A.
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Formic Acid ◽  
Total Pressure ◽  
High Speed ◽  
Reaction Rate ◽  
First Order ◽  
Gaseous Products ◽  
Retarding Effect

This paper deals with the action of cathode rays on gases and gas mixtures. Methane, methane-oxygen mixtures, carbon monoxide and carbon monoxide-oxygen mixtures were examined. Methane gave small percentages of hydrogen and ethane. Methane and oxygen mixtures gave as gaseous products, carbon monoxide, carbon dioxide and hydrogen, the only other products being water and formic acid. The relative proportions of the products do not vary widely under a wide variation of conditions.The reaction was found to be of the first order with respect to pressure. The reaction rate increases linearly with the voltage up to a certain value, after which it becomes nearly independent of the voltage.The action of cathode rays on carbon monoxide produces carbon dioxide and a solid brown suboxide which is extremely soluble in water, and its composition corresponds to a formula (C3O)n. If the carbon monoxide is moist, no visible amount of solid or liquid is found and there is less carbon dioxide.Carbon monoxide-oxygen mixtures under the action of cathode rays form carbon dioxide. Presence of water vapor has a retarding effect on the reaction. For mixtures of the same composition the reaction rate is proportional to the total pressure. For dry mixtures the product increases with the carbon monoxide present; when moist it is much less, and independent of the carbon monoxide.

Decomposition of PCB's in the radio-frequency glow discharge plasmas of oxygen, hydrogen, and water vapor

1982 ◽  
Vol 60 (22) ◽  
pp. 2876-2882 ◽  
Author(s):  
K. Hiraoka ◽  
K. Aoyama ◽  
T. Nakamura ◽  
S. Mochizuki ◽  
K. Mitsumori ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Glow Discharge ◽  
Radio Frequency ◽  
Hydrogen Chloride ◽  
Hydrogen Plasma ◽  
Glow Discharge Plasma ◽  
Radio Frequency Glow Discharge ◽  
Gaseous Products

A study was made on the decomposition of PCB's in a radio-frequency glow discharge plasma. PCB's were completely decomposed in plasmas of a few Torr of oxygen, hydrogen, and water vapor. Gaseous products from PCB's in an oxygen plasma were carbon monoxide, carbon dioxide, water, hydrogen chloride, chlorine, and chlorine dioxide. Hazardous compounds such as phosgene and vinyl chloride were not detected by gc–ms analysis. The total quantity of oxygen flowed past the sample was only about three times the stoichiometric oxygen required for the perfect oxidation of PCB's. In a hydrogen plasma, PCB's gave ethane and isobutane as major gaseous products and several higher hydrocarbons as minor products. Almost all of the chlorine in PCB's was converted to hydrogen chloride. Major products from PCB's in a water vapor plasma were carbon dioxide, carbon monoxide, and hydrogen chloride. No other products were detected. The mechanisms for reactions occurring in plasmas are discussed. The importance of the wall effect for the formation of solid products is discussed.

scholarly journals Thermodynamic and Chemical Analysis of Water-Coal Fuel Ignition and Combustion in Adiabatic Combustion Chamber

2021 ◽  
pp. 385-398
Author(s):  
Viktor I. Karpenok ◽  
Vasily I. Murko ◽  
Vera P. Mastikhina ◽  
Yulia A. Loboda
Keyword(s):  
Water Vapor ◽  
Solid Phase ◽  
Equilibrium Constants ◽  
Combustion Process ◽  
Ash Content ◽  
Volatile Substances ◽  
Leading Role ◽  
Coal Fuel ◽  
Coal Particles ◽  
Ignition And Combustion

The article presents results of improvement of physicochemical model of coal-water fuel ignition and combustion processes, taking into account ash content and release of volatile substances of solid phase. In this case, model of ignition and combustion of two systems of atomized coal-water fuel: drops and pure coal particles is taken as a basis. As a result of the analysis, the influence of ash content of coal-water fuel on output of combustible gases and content of water vapor in furnace atmosphere was established. Based on comparison of the diffusion coefficients of gases and the calculated values of equilibrium constants of reaction in combustion zone, conclusion has been of the leading role of water vapor oxidation of carbon in vortex adiabatic furnace. Performed numerical calculations have shown that combustion process of the above inhomogeneous systems (droplets and particles) in an adiabatic furnace within a short time becomes identical. Concentrations of volatile substances, oxygen (O2) and carbon dioxide (CO2) in various sections of the furnace have been established

Appropriate Mean Absorption Coefficients for Infrared Radiation of Gases

1967 ◽  
Vol 89 (4) ◽  
pp. 321-327 ◽  
Author(s):  
M. M. Abu-Romia ◽  
C. L. Tien
Keyword(s):  
Carbon Dioxide ◽  
Heat Flux ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Thermodynamic Properties ◽  
Infrared Radiation ◽  
Radiative Heat ◽  
Radiative Heat Flux ◽  
Absorption Coefficients ◽  
Planar Medium

In this paper, a study is made on the calculation of appropriate mean absorption coefficients for the infrared radiation of gases. The Planck and Rosseland mean absorption coefficients for the optically thin and optically thick gases are expressed as functions of the spectroscopic and thermodynamic properties of the gas. Values of the Planck and Rosseland mean absorption coefficients are presented for carbon monoxide, carbon dioxide, and water vapor in the temperature range from 1000 to 5000 deg Rankine. To illustrate the application of these results, the radiative heat flux is calculated for the simple case of a planar medium.

High Temperature Corrosion and Evaporation of Haynes 25 and Hastelloy X-280

CORROSION ◽  
1967 ◽  
Vol 23 (2) ◽  
pp. 50-57 ◽  
Author(s):  
L. A. CHARLOT ◽  
R. E. WESTERMAN
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
High Temperature ◽  
Inert Atmosphere ◽  
High Temperature Corrosion ◽  
Pure Oxygen ◽  
Metal Loss ◽  
Hastelloy X ◽  
Oxidation Rates

Abstract The corrosion behavior of Hastelloy X-280 and Haynes 25 at 1120 C (2048 F) in atmospheres of oxygen, carbon monoxide, carbon dioxide, water vapor and methane has been investigated. Evaporation rates of the superalloys in vacuo have been determined to 1200 C (2192 F). Oxidation rates generally were found to increase with increasing pressure in the range 0.04 to 760 torr. Oxidation rates in other oxidants were less than those in pure oxygen. Thermal cycling reduced the oxidation resistance of Haynes 25. Both alloys carburize readily at 1120 C in a methane atmosphere. The carburization process can be reversed easily and ductility recovered by exposing material to oxidizing atmosphere at the same temperature. Evaporation of superalloys in vacuo at 1120 C can result in metal loss approximating that found under oxidizing conditions. Preformed oxide films are shown to be ineffective barriers to evaporation in an inert atmosphere (vacuum) at 1120 C.

scholarly journals Water vapor release from biofuel combustion

2008 ◽  
Vol 8 (2) ◽  
pp. 4483-4498 ◽  
Author(s):  
R. S. Parmar ◽  
M. Welling ◽  
M. O. Andreae ◽  
G. Helas
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Moisture Content ◽  
Biomass Burning ◽  
African Savanna

Abstract. We report on the emission of water vapor from biofuel combustion. Concurrent measurements of carbon monoxide and carbon dioxide are used to scale the concentrations of water vapor found, and are compared to carbon in the biofuel. Fuel types included hardwood (oak and African musasa), softwood (pine and spruce, partly with green needles), and African savanna grass. The session-averaged ratio of H2O to the sum of CO and CO2 in the emissions from 16 combustion experiments ranged from 1.2 to 3.7 on average, indicating the presence of water that is not chemically bound. This biofuel moisture content ranged from 33% in the dry African hardwood, musasa, to 220% in fresh pine branches with needles. The moisture content from fresh biofuel contributes distinctly to the water vapor in biomass burning emissions, and its influence on meteorology needs to be evaluated.

Mathematical Modeling of Heat and Mass Transfer Processes During Pyrolysis and Combustion of a Single Biomass Particle

2012 ◽  
Author(s):  
Y. Haseli ◽  
J. A. van Oijen ◽  
L. P. H. de Goey
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Gas Phase ◽  
Combustion Process ◽  
Combustion Model ◽  
Gas Phase Reactions ◽  
Transfer Processes ◽  
Mass Transfer Processes

A detailed mathematical model is developed for simulation of heat and mass transfer processes during the pyrolysis and combustion of a single biomass particle. The kinetic scheme of Shafizadeh and Chin is employed to describe the pyrolysis process. The light gases formed during the biomass pyrolysis is assumed to consist of methane, carbon dioxide, carbon monoxide, hydrogen and water vapor with given mass fractions relevant to those found in the experiments of high heating conditions. The combustion model takes into account the reactions of oxygen with methane, hydrogen, carbon monoxide, tar and char as well as gasification of char with water vapor and carbon dioxide. Appropriate correlations taken from past studies are used for computation of the rate of these reactions. The model allows calculation of time and space evolution of various parameters including biomass and char densities, gaseous species and temperature. Different experimental data reported in the literature are employed to validate the pyrolysis and combustion models. The reasonable agreement obtained between the predictions and measured data reveals that the presented model is capable of successfully capturing various experiments of wood particle undergoing a pyrolysis or combustion process. In particular, the role of gas phase reactions within and adjacent to particle on the combustion process is examined. The results indicate that for the case of small particles in the order of millimeter size and less, one may neglect any effects of gas phase reactions. However, for larger particles, a combustion model may need to include hydrogen oxidation and even carbon monoxide combustion reactions.

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