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  • Print publication year: 2010
  • Online publication date: February 2011

15 - Gasification, pyrolysis, and combustion


A common set of reactions, given in Table 15.1, occurs when carbonaceous solids undergo thermal processing. Whether the aim is pyrolysis, gasification, or combustion, each of these reactions occurs in some parts of the reactor because of gas–solids contacting. In this chapter, we consider, in order, gasification as an endothermic process to generate H2 and CO mixtures for fuel or synthesis gas, pyrolysis as a process to generate useful tars (or liquids), and combustion as a process to produce heat.

Gasification background

Most commercial gasifiers use coal as feed, and may be classified by the type of solids–gas contacting (moving, entrained, fluidized, or spouted bed), by the state of the ash (dry, agglomerated, or molten), and by the oxidant (air, air–steam, or oxygen–steam). A low-calorific-value gas results from air–steam gasification, and a medium-calorific-value gas from using steam or steam–oxygen mixtures. The carbonaceous feedstock may be fed as a dry solid, a sludge, or a slurry.

Performance measures can be identified for comparing gasifiers of different designs and operating conditions. For production of fuel gases, the heating value of the produced gas is important and is usually reported on a dry gas basis. For synthesis gas or pure hydrogen production, the molar ratio of H2∕CO leaving the gasifier is critical. Low tar yields are usually beneficial, unless a raw fuel gas is desired. For sizing scaled-up gasification processes, throughput of solids feed per unit cross-section of reactor (kg/m2s) is of major importance.

Fernando, R.. Coal Gasification. International Energy Agency Clean Coal Centre Report CCC/140, Oct. 2008.
Foong, S. K., Lim, C. J., and Watkinson, A. P.. Coal gasification in a spouted bed. Can. J. Chem. Eng., 58 (1980), 84–91.
Foong, S. K., Cheng, G., and Watkinson, A. P.. Spouted bed gasification of Western Canadian coals. Can. J. Chem. Eng., 59 (1981), 625–630.
Watkinson, A. P., Cheng, G., and Prakash, C. B.. Comparison of coal gasification in fluidized and spouted beds. Can. J. Chem. Eng., 61 (1983), 468–473.
Watkinson, A. P., Cheng, G., and Lim, C. J.. Oxygen-steam gasification of coals in a spouted bed. Can. J. Chem. Eng., 65 (1987), 791–798.
Watkinson, A. P., Cheng, G., and Fung, D. P. C.. Gasification of oil sand coke. Fuel, 68 (1989), 4–10.
Haji-Sulaiman, Z., Lim, C. J., and Watkinson, A. P.. Gas composition and temperature profiles in a spouted bed coal gasifier. Can. J. Chem. Eng., 64 (1986), 125–132.
Kikuchi, K., Suzuki, A., Mochizuki, T., Endo, S., Imai, E., and Tanji, Y.. Ash-agglomerating gasification of coal in a spouted bed reactor. Fuel, 64 (1985), 368–372.
Uemaki, O. and Tsuji, T.. Gasification of a sub-bituminous coal in a two-stage jet-spouted bed reactor. In Fluidization V, ed. Ostergaard, K. and Sorensen, A. (New York: Engineering Foundation, 1986), pp. 497–504.
Tsuji, T., Shibata, T., Yamaguchi, K., and Uemaki, O.. Mathematical modeling of spouted bed coal gasification. In Proceedings of the International Conference on Coal Science (Tokyo: New Energy Development Organization, 1989), pp. 457–460.
Tsuji, T. and Uemaki, O.. Coal gasification in a jet-spouted bed. Can. J. Chem. Eng., 72 (1994), 504–510.
Gale, J. and Bower, C. J.. Development of the British Coal gasification process for the manufacture of low calorific value gas. Presented at Applied Energy Conference, Swansea, September 1989.
St, M.. Arnold, J., Gale, J. J., and Laughlin, M. K.. The British Coal spouted fluidised bed gasification process. Can. J. Chem. Eng., 70 (1992), 991–997.
Sue-A-Quan, T., Watkinson, A. P., Gaikwad, R. P., Lim, C. J., and Ferris, B. R.. Steam gasification in a pressurized spouted bed reactor. Fuel Proc. Technol., 27 (1991), 67–81.
Sue-A-Quan, T., Cheng, G., and Watkinson, A. P.. Coal gasification in a pressurized spouted bed. Fuel, 74 (1995), 159–164.
Hatate, Y., Uemura, Y., Tanaka, S., Tokumasu, Y., Tanaka, Y., King, D. F., and Ijichi, K.. Development of a spouted bed-type coal gasifier with cycling thermal medium particles. Soc. Chem. Engrs, Japan, 20 (1994), 758–764.
Xiao, R., Zhang, M., Jin, B., and Huang, Y.. High-temperature air/steam-blown gasification of coal in a pressurized spout-fluid bed. Energy & Fuels, 20 (2006), 715–720.
Xiao, R., Zhang, M., Jin, B., Xiaong, Y., Zhou, H., Duan, Y., Zhong, Z., Chen, X., Shen, L., and Huang, Y. Air blown partial gasification of coal in a pilot plant pressurized spout-fluid bed reactor. Fuel, 86 (2007), 1631–1640.
Moore, D. L., Haq, Z., Pinkston, T. E., Rush, R. E., Vimalchaud, P., McClung, J. D., and Quandt, M. T.. Status of the advanced PFBC at the Power Systems Development Facility. Report DOE/MC/25140–94/C0353 (1994), pp. 127–137.
Paterson, N., Zhuo, Y., Dugwell, D. R., and Kandiyoti, R.. Investigation of ammonia formation during gasification in an air-blown spouted bed: reactor design and initial tests. Energy & Fuels, 16 (2002), 127–135.
Zhuo, Y., Paterson, N., Avid, B., Dugwell, D. R., and Kandyoti, R.. Investigation of ammonia formation during gasification in an air blown spouted bed: the effect of the operating conditions on ammonia formation and the identification of ways of minimizing its formation. Energy & Fuels, 16 (2002), 742–751.
Paterson, N., Zhuo, Y., Reed, G. P., Dugwell, D. R., and Kandiyoti, R.. Pyrolysis and gasification of sewage sludge in a spouted-bed reactor. Water & Envir. J., 18 (2004), 90–94.
Hanson, S., Patrick, J. W., and Walker, A.. The effect of coal particle size on pyrolysis and steam gasification. Fuel, 81 (2002), 531–547.
Zak, C. and Nutcher, P. B.. Spouted fluid-bed gasification of biomass and chemical wastes-some pilot plant results. In Energy from Biomass and Wastes X, ed. Klass, D. K. (London: Elsevier and Chicago: Institute of Gas Technology, 1987), pp. 643–653.
,U.S. Environmental Protection Agency Report EPA/540/F-93/XXX. “Energy Technology Bulletin – Spouted Bed Reactor,” Energy and Environmental Research Corporation (Irvine, CA, 1993).
Thamavithya, M. and Dutta, A.. An investigation of MSW gasification in a spout-fluid bed reactor. Fuel Proc. Technol., 89 (2008), 949–957.
Salam, P. A. and Bhattacharya, S. C.. A comparative study of charcoal gasification in two types of spouted bed reactors. Energy, 31 (2006), 228–243.
Hoque, M. M. and Bhattacharya, S. C.. Fuel characteristics of gasified coconut shell in a fluidized and a spouted bed reactor. Energy, 26 (2001), 101–110.
Lim, C. J., Lucas, J. P., Haji-Sulaiman, M., and Watkinson, A. P.. A mathematical model of a spouted bed gasifier. Can. J. Chem. Eng., 69 (1991), 596–606.
Lucas, J. P., Lim, C. J., and Watkinson, A. P.. A non-isothermal model of a spouted bed coal gasifier. Fuel, 77 (1998), 683–694.
Song, B. H. and Watkinson, A. P.. Three-stage well-mixed reactor model for a pressurized coal gasifier. Can. J. Chem. Eng., 78 (2000), 143–155.
Li, Q., Zhang, M., Zhong, W., Wang, X., Xiao, R., and Jin, B.. Simulation of coal gasification in a pressurized spout-fluid bed gasifier. Can. J. Chem. Eng., 87 (2009), 169–176.
Barton, R. K., Rigby, G. R., and Ratcliffe, J. S.. The use of a spouted bed for the low temperature carbonization of coal. Mech. Chem. Eng. Trans., 4 (1968), 105–112.
Berti, L. P. and Gary, J. H.. Spouted bed oil shale retort. Colorado School of Mines Quart., 61 (1966), 553–560.
Tamm, P. W. and Kuehler, C. W., Spouted-bed shale retorting process. U.S. Patent 4,125,453 (1978).
Leite, A. C. B., Wodtke, R. M. P., Lisboa, A. C. L., and Restini, F.. Pyrolysis of oil shale fines in a spouted bed reactor. XVI Congresso Latino Americano de Quimica, Rio de Janeiro, October 1984.
Lisboa, A. C. L. and Watkinson, A. P.. Pyrolysis with partial combustion of oil shale fines in a spouted bed. Can. J. Chem. Eng., 70 (1992), 983–990.
Teo, K. C. and Watkinson, A. P.. Rapid pyrolysis of Canadian coals in a miniature spouted bed reactor. Fuel, 65 (1986), 949–959.
Jarallah, A. and Watkinson, A. P.. Pyrolysis of Western Canadian coals in a spouted bed. Can. J. Chem. Eng., 63 (1985), 227–236.
Tam, T.. Pyrolysis of oil shale in a spouted bed pyrolyser. M.A.Sc. thesis, University of British Columbia (1987).
Rovero, G. and Watkinson, A. P.. A two-stage spouted bed process for auto-thermal pyrolysis or retorting. Fuel Proc. Technol., 26 (1990), 221–238.
Aguado, R., Olazar, M., , M.José, San, Aguirre, G., and Bilbao, J.. Pyrolysis of sawdust in a conical spouted bed reactor. Yields and product composition, Ind. Eng. Chem. Res., 39 (2000), 1925–1933.
Janarthanan, A. K. and Clements, L. D.. Gasification of wood in a pilot scale spouted bed gasifier. In Dev. Thermochem. Biomass Conversion, vol. 2, ed. Bridgwater, A. V. and Boocock, D. G. B. (Amsterdam: Kluwer Academic, 1997), pp. 945–959.
Chen, M., Wang, J., Wang, X., Zhang, X., Zhang, S., Ren, Z., and Yan, Y.. Fast pyrolysis of biomass in a spout-fluidized bed reactor–analysis of composition and combustion characteristics of liquid product from biomass. Chin. J. Proc. Eng., 6 (2006), 192–96.
Jurewicz, J. and Lemoine, A.. Solid oxide fuel cell combustible by plasma spouted bed gasification of granulated biomass. Prep. Pap. Amer. Chem. Soc. Div. Fuel Chem., 49 (2004), 916–917.
Lim, C. J., Barua, S. K, Epstein, N., Grace, J. R., and Watkinson, A. P.. Spouted bed and spout-fluid bed combustion of solid fuels. In Fluidised Combustion: Is It Achieving Its Promise? Third International Fluidised Bed Combustion Conference, Institute of Energy, London (1984).
Zhao, J. C., Lim, C. J., and Grace, J. R. Coal burnout times in spouted and spouted-fluid beds. Chem. Eng. Res. Dev., 65 (1987), 426–429.
Zhao, J. C., Lim, C. J., and Grace, J. R.. Flow regimes and combustion behavior in coal-burning spouted and spout-fluid beds. Chem. Eng. Sci., 42 (1987), 2865–2875.
Lim, C. J., Watkinson, A. P., Khoe, G. K., Low, S., Epstein, N., and Grace, J. R.. Spouted, fluidized and spout-fluid bed combustion of bituminous coals. Fuel, 67 (1988), 1211–1217.
Shirley, F. W. and Litt, R. D. Advanced atmospheric fluidized-bed combustion design-spouted bed. Final Report to U.S. Department of Energy from Battelle Columbus Laboratories, February 1988.
Vuthaluru, H. B., Linjewille, T. M., Zhang, D., and Manzoori, A. R.. Investigations into the control of agglomeration and defluidisation during fluidised-bed combustion of low-rank coals. Fuel, 78 (1999), 419–425.
Vuthaluru, H. B. and Zhang, D.. Control methods for remediation of ash-related problems in fluidised-bed combustors. Fuel Proc. Technol., 60 (1999), 145–156.
Vuthaluru, H. B., Zhang, D., and Linjewile, T. M.. Behaviour of inorganic constituents and ash characteristics during fluidised-bed combustion of several Australian low-rank coals. Fuel Proc. Technol., 67 (2000), 165–176.
Vuthaluru, H. B. and Zhang, D.. Effect of coal blending on particle agglomeration and defluidisation during spouted-bed combustion of low-rank coals. Fuel Proc. Technol., 70 (2001), 41–51.
José, M. J. San, Aguado, M. J., Alvarez, S., and Bilbao, J.. Combustion of sawdust and forestry waste in conical spouted beds. Rev. de Inform. Tecnol. 13 (2002), 133–137.
Khoshnoodi, M. and Abidin, R. Z.. Utilization of Malaysian peat in spouted bed burner. In Proceedings of the 10th Malaysian Chemical Engineering Symposium (Penang: Institute of Chemical Engineers, Malaysia, 1994).
Altwicker, E. R., Konduri, R. K. N., and Milligan, M. S.. Spouted bed combustor for the study of heterogeneous hazardous waste incineration. AIChE Meeting, Philadelphia, Paper 82c (1989).
Baker, R. S. and Wilkinson, R. C.. The commercial development of spouted/fluidised bed combustion in Australia. In Fluidised Combustion: Systems and Applications. Institute of Energy Symposium Series, Vol. 1, No. 4 (1980), pp. 1–11.
Albina, D. O.. Combustion of rice husk in a multiple-spouted fluidized bed. Energy Sources, 25 (2003), 893–904.
Albina, D. O., Emissions from multiple-spouted and spout-fluid beds using rice husks as fuel. Renew. Energy, 31 (2006), 2152–2163.
Barz, M.. Sewage sludge combustion in a spouted bed cascade system. China Particuology, 1 (2003), 223–228.
Rasul, M. G.. Spouted bed combustion of wood charcoal: performance comparison of three different designs. Fuel, 80 (2001), 2189–2191.
Arbib, H. A. and Levy, A.. Combustion of low heating value fuels and wastes in the spouted bed. Can. J. Chem. Eng., 60 (1982), 528–531.
Bilbao, J., Olazar, M., and José, M. J. San. Dispositivo para la combustion en continuo de residuos solidos, Oficina Espanola de Patentes y Marcas, 2,148,026 (2001), 9 pages.