Changes in total active centres on particle surfaces during coal pyrolysis, gasification and combustion

• Authors: Stanisław Gil , Piotr Mocek , Wojciech Bialik
• Languages of publication: EN

Abstracts

EN

In the paper, on the basis of our studies and the available literature data, a model of changes in the number of active centers corresponding to the structure of the reactive coal particle has been developed. A new distribution function that links the specific surface area of a particle with its porosity and reaction degree has been proposed. An equation for estimation of changes in this parameter during the reaction, on the basis of the initial value, has been presented. In the range of our data and the analysis of the literature data, the model, with satisfactory accuracy, describes internal structural changes of coal and coal char particles. The present results may constitute a basis for complex modelling of coal conversion processes.Based on the results it was found that the total active centres are related to the internal surface area and porosity of the particle. For a specific coal type, this value depends on the porosity, true density and size of the particle. Changes in total active centres, when these structural properties during thermal conversion of coal are considered, are described in equations.

Keywords

EN

coal; active centers; porosity

• Publisher: De Gruyter Open
• Journal: Chemical and Process Engineering
• Year: 2011
• Volume: 32
• Issue: 2
• Pages: 155-169

Dates

published

1 - 6 - 2011

online

11 - 7 - 2011

Contributors

author

Stanisław Gil

• Department of Metallurgy, Group of Process Energy, Silesian University of Technology, ul. Krasinskiego 8, 40-019 Katowice, Poland

author

Piotr Mocek

• Department of Metallurgy, Group of Process Energy, Silesian University of Technology, ul. Krasinskiego 8, 40-019 Katowice, Poland

author

Wojciech Bialik

• Department of Metallurgy, Group of Process Energy, Silesian University of Technology, ul. Krasinskiego 8, 40-019 Katowice, Poland

References

• Agrawal A.K., Sears J.T., 1980. The coal char reactions with CO2-CO gas mixtures. Ind. Eng. Chem. Process Des. Dev., 19, 364-371. DOI: 10.1021/i260075a006.[Crossref]
• Anthony D.B., Howard J.B., 1976. Coal devolatilization and hydrogasification. AIChE J., 22, 625-656. DOI: 10.1016/0016-2361(76)90008-9.[Crossref]
• Blackwood J.D., McCarthy D.J., 1966. The mechanism of hydrogenation of coal to methane. Aust. J. Chem., 19, 797-813. DOI:10.1071/CH9660797.[Crossref]
• Croiset E., Heurtaebise C., Rouan J.P., Richarad J.R., 1998. Influence of pressure on the heterogeneous formation and destruction of nitrogen oxides during char combustion. Combust. Flame, 112, 33-44. DOI:10.1016/S0010-2180(97)81755-5.[Crossref]
• Croiset E., Mallet Ch., Rouan J.P., Richard J.R., 1996. The influence of pressure on char combustion kinetics. 26th International Symposium on Combustion. The Combustion Institute, Pittsburgh, 3096-3102. DOI: 10.1016/S0082-0784(96)80153-6.[Crossref]
• Feng B., Bhatia S. K., 2003. Variation of the pore structure of coal chars during gasification. Carbon, 41, 507-523. DOI:10.1016/S0008-6223(02)00357-3.[Crossref]
• Floess J.K., Longwell J.P., Sarofim A.F., 1988. Intrinsic reaction kinetics of microporous carbons. 1. Noncatalyzed chars. Energy Fuels, 2, 18-26. DOI: 10.1021/ef00007a004.[Crossref]
• Freise E. J., 1962. Structure of graphite. Nature, 193, 671-672. DOI: 10.1038/193671a0.[Crossref]
• Gil S., 2000. Research on the influence of pressure on kinetics of coal nitrogen conversion during pyrolysis and combustion. PhD Thesis. Silesian University of Technology, Katowice.
• Gil S., 2002. Influence of combustion pressure on fuel-N conversion to NO, N2O and N2. Karbo, 9, 272-275.
• Gil S., 2003. Kinetics of heterogeneous nitrogen oxides formation during pressurized char combustion. Grant KBN PAN No. 4 T10B 029 22, 1075/T10/2002/22
• Hurt R.H., Sarofim A.F., Longwell J.P., 1991. Effect of nonuniform surface reactivity on the evolution of pore structure and surface area during carbon gasification. Energy Fuels, 5, 463-468. DOI: 10.1021/ef00027a018.[Crossref]
• Johnson J.L., 1987. Kinetics of coal gasification. John Wiley & Sons, New York.
• Johnson J.L., 1975. Relationship between the gasification reactivities of coal char and the physical and chemical properties of coal and coal char. American Chemical Society, Division of Fuel Chemistry, 20, 85-102.
• Kothandaraman G., Simons G.A., 1984. Evolution of the pore structure in PSOC140 liquite during pyrolysis. 20th International Symposium on Combustion. The Combustion Institute, Pittsburgh, 1523-1529. DOI: 10.1016/S0082-0784(85)80646-9.[Crossref]
• Kowol J., Tomeczek J., 1988. Kinetics of main products formation during coal devolatilization. Erdöl und Kohle, 41, 161-165.
• Krammer G.F., Sarofim A.F., 1994. Reaction of char nitrogen during fluidized bed coal combustion - influence of nitric oxide and oxygen on nitrous oxide. Combust. Flame, 97, 118-124. DOI: 10.1016/0010-2180(94)90120-1.[Crossref]
• Külaots I., Aarna I., Calleyo M., Hurt R.H., Suuberg E.M., 2002. Development of porosity during coal char combustion. Proc. Combust. Inst., 23, 495-501. DOI:10.1016/S1540-7489(02)80064-5.[Crossref]
• Laine N.R., Vastola F.J., Walker P.L., 1963. The importance of active surface area in the carbon-oxygen reaction. J. Phys. Chem., 67, 2030-2034.
• Mlonka J., 1992. Research over the kinetics of structural changes and theirs influence on coal pyrolysis process. PhD Dissertation. Silesian University of Technology, Katowice.
• Simons G.A., 1984. Coal pyrolysis. II. Species transport theory. Combust. Flame, 55, 181-194. DOI:10.1016/0010-2180(84)90026-9.[Crossref]
• Smith J.M., 1970. Chemical engineering kinetics. McGraw Hill, New York.
• De Soete G.G., 1990. Heterogeneous N2O and NO formation from bound nitrogen atoms during coal char combustion. 23rd International Symposium on Combustion. The Combustion Institute, Pittsburgh, 1257-1264. DOI:10.1016/S0082-0784(06)80388-7.[Crossref]
• Solomon P.R., Colket M.B., 1978. Evolution of fuel nitrogen in coal devolatilization. Fuel, 57, 749-755. DOI:10.1016/0016-2361(78)90133-3.[Crossref]
• Sotirchos S.V., 1987. On a class of random pore and particle models for gas-solid reactions. Chem. Eng. Sci., 42, 1262-1265. DOI: 10.1016/0009-2509(87)80084-2[Crossref]
• Stanmore B.R., 1991. Modeling of combustion behavior of petroleum coke. Combust. Flame, 83, 221-227. DOI:10.1016/0010-2180(91)90070-R.[Crossref]
• Suuberg E.M., Peters W.A., Howard J.B., 1979. Product compositions and formation kinetics in rapid pyrolysis of pulverized coal - implications for combustion. 17th International Symposium on Combustion. The Combustion Institute, Pittsburgh, 117-130. DOI:10.1016/S0082-0784(79)80015-6.[Crossref]
• Suuberg E.M., Külaots I., Aarna I., Calleyo M., Vrager A., Deutsch D., 2003. Study of activation of coal char. Proceedings of the DOE Grants DE-FG 26 99FT-40582
• Tomeczek J., Gil S., 1995. Kinetics of porosity evolution during fast heating of coal. 8th International Conference on Coal Science, Oviedo, 925-928.
• Tomeczek J., Gil S., 2003. Volatiles release and porosity evolution during high pressure coal pyrolysis. Fuel, 82, 285-292. DOI:10.1016/S0016-2361(02)00256-9.[Crossref]
• Visona S.P., Stanmore B.R., 1996. Modeling NOx release from a single coal particle. II. Formation of NO from char-nitrogen. Combust. Flame, 106, 207-218. DOI: 10.1016/0010-2180(95)00257-X.[Crossref]

Identifiers

DOI

10.2478/v10176-011-0012-8