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Combustion of Coal Volatiles in the Freeboard of a Fluidized Bed Combustor: an Experimental Approach
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Abstract
Previous attempts to determine the amount of volatile material transferred into and burnt in the freeboard region (FBR) of fluidized bed coal combustors have been few and/or ambiguous. A major reason for this is the difficulty of separating the two combustion processes (volatiles and char) occurring simultaneously within both bed and freeboard sections, and because the instrumentation for measuring these separate phenomena directly is non-existent. Therefore, a calorimetric technique is reported here to produce quantitative information on the fraction of heat released by the volatile component in the FBR. The calorimetric experiments revealed that over one third of the original volatiles may be released and burnt above the bed at low excess air levels (< 10 %) and low bed temperatures (< 850°C), for shallow beds (0.2 m) and small bed particle size (0.674 mm); while a low transfer of volatile matter was measured at high bed temperatures (> 850°C) and high excess air levels (up to 40 %). The transfer of coal volatiles in the FBR was found to be influenced by the in-bed operating and fluidizing conditions in the following order: bed temperature (Tb), excess air (XSA), fluidizing velocity (Uo) and coal particle size (dc).
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References
The Institute of Energy, FBC Technology and the Environmental Challenge, 5th Int. Conf. on Fluidized Bed Combustion. London, U.K. (1991).
B.A. Andersoon, B. Leckner and L.E. Ammand, Fluidized-Bed Combustion of Coals and Alternative Fuels, 8th Int. Conf. on Fluidized Bed Combustion. Houston, USA (1985).
R. Carson, TVA 160-MWe AFBC Demonstration Plant Process Performance, 11th Int. Conf. on Fluidized Bed Combustion, Clean Energy for the World. Montreal, Canada (1991).
S.N. Oka, Fluidized Bed Combustion (Marcel Dekker, 2004).
K.K. Pillai, The Influence of Coal Type on Devolatilization and Combustion in Fluidized Beds, J. Inst. Energy 54 (1981) 142-150.
R.P. Krisnhan, J. Anthony, M. Rajavel, S.V. Srinivasan and A.V.J. Rao, Combustion of High Ash Indian Coals in a Fluidized Bed Combustor, Fuel 70 (1991) 1125-1135.
R.G. Bautista-Margulis, Determination of the Rate of Transfer of Volatile Matter into the Freeboard of a Fluidized Bed Coal Combustor, PhD. dissertation, Dept. Chem. Eng. and Fuel Tech., Sheffield Univ., U.K., 1993.
J.F. Stubington and S.W. Chan, Experimental Measurements of Combustion of Simulated Coal Volatiles in a Bubbling Fluidized Bed Combustor, Fuel 69 (1990) 678-683.
E. Turnbull, Fluidized Bed Combustion of Char and Volatiles from Coal, PhD. dissertation, Trinity College, Cambridge Univ., U.K., 1983.
K. Jung and B.R. Stanmore, Fluidized Bed Combustion of Wet Brown Coal, Fuel 59 (1980) 74-80.
R.P. Hesketh and J.F. Davidson, Combustion of Methane and Propane in an Incipiently Fluidized Bed, Combustion and Flame 85 (1991) 449-467.
D.R. Van Der Vaart, The Chemistry of Premixed Hydrocarbons/Air Combustion in a Fluidized Bed, Combustion and Flame 71 (1988) 35-39.
J.S. Dennis, A.A. Hayhurst and I.G. Mackcley, The Ignition and Combustion of Propane/Air Mixtures in a Fluidised Bed, 19th Symp. (Int.) on Combustion, The Combustion Institute, Pittsburgh, USA (1982).
D.P. Ross, H.M. Yan and D.K. Zhang, An Experimental Study of Propane Combustion in a Fluidized-Bed Gasifier, Combustion and Flame 124 (2001) 156-164.
J.F. Stubington and Sumaryono, Release of Volatiles from Large Coal Particles in a Hot Fluidized Bed, Fuel 63 (1984) 1013-1019.
M.K. Urkan, D. Bilge, M. Arikol and H.A. Heperkan, Devolatilization of Some Turkish Lignites in a Fluidized Bed, Int. Conf. of Coal Science, Maastrich, The Netherlands (1987).
A.E. Wildegger-Gaissmaier and P.K. Agarwal, Drying and Devolatilization of Large Coal Particles Under Combustion Conditions, Fuel 69 (1990) 44-52.
J.Q. Zhang, H.A. Becker and R.K. Code, Devolatilization of Large Coal Particles in a Fluidized Bed, 9th Int. Conf. on Fluidized Bed Combustion, FBC Comes of Age, Boston, Massachusetts, USA (1987).
M. Komatina, M. Ilic and S. Oka, Temperature of the Coal Particle During Process of Heating, Drying and Devolatilization in Fluidized Bed, Dubrovnik Conf. on Sustainable Development of Energy, Water and Environment Systems, Dubrovnik, Croatia (2002).
W. Prins, Fluidized Bed Combustion of a Single Carbon Particle, PhD. dissertation, Twenty Univ., The Netherlands, 1987.
M. Komatina, M. Ilic and S. Oka, The Model of Drying and Devolatilization of the Coal Particle in Fluidized Bed, 4th Symp. of South-East European Countries (SEEC), Fluidized Beds in Energy Production, Chemical, Process Engineering and Ecology. Thessaloniki, Greece (2003).
T.F. Salam, S.A. Nadeem, K.I. Omar and B.M. Gibbs, Combustion Characteristics of Bangladeshi Peat in a Fluidized Bed Combustor, 4th Int. Conf. on Fluidized Bed Combustion, Fluidized Bed Combustion in Practice: Clean, Versatile, Economic?. London, U.K. (1988).
D. Dakić, G. Van Der Honing, and M. Valk, Fragmentation and Swelling of Various Coals During Devolatilization in a Fluidized Bed, Fuel 68 (1989) 911-916.
D. Dakić, B. Grubor and S. Oka, Experimental Results of Primary Coal Fragmentation in Fluidized Bed for Eight Different Coals - New Interpretation of Results, Proc. of the Workshop “Attrition Phenomena in Fluidized Bed Conversion of Fossil/Non Fossil Fuels. Salerno, Italy (2000).
H. Zhang, K. Cen , J. Yan and M. Ni, The Fragmentation of Coal Particles During the Coal Combustion in a Fluidized Bed, Fuel 81 (2002) 1835-1840.
C. Pinho, Fragmentation on Batches of Coke or Char Particles During Fluidized Bed Combustion, Chemical Engineering Journal 115 (2006) 147-155.
R.C. Borah, P. Ghosh and P.G. Rao, Devolatilization of Coals of North-Eastern India Under Fluidized Bed Conditions in Oxygen-Enriched Air, Fuel Processing Technology 89 (2008) 1470-1478.
J.F. Stubington, G. Huang and A.W. Scaroni, Devolatilization Times of mm-Sized Coal Particles, Fuel 70 (1991) 1105-1108.
R.D. La Nauze, Fundamentals of Coal Combustion in Fluidised Beds, Chem. Eng. Research and Design 63 (1985) 3-33.
D. Kunii and O. Levenspiel, Fluidization Engineering (Butterworth-Heinemann, 1991).
J.F. Stubington, The Role of Coal Volatiles in Fluidized Bed Combustion, J. Inst. Energy 53 (1980) 191-195.
Y.Y. Lee, A.F. Sarofim and J.M. Beer, Effects of Modes of Coal Feeding on Coal Volatile Release in Fluidized-Bed Combustors, 1st Int. Symp. on Fluidized Bed Combustion and Applied Technology, New York, USA (1984).
Y.Y. Lee, Effects of Volatile Evolution and Combustion on the Design of Coal Feeding System in Atmospheric Fluidized-Bed Combustors, 8th Int. Conf. on Fluidized Bed Combustion, Houston, USA (1985).
J.P. Holman, Heat Transfer (McGraw Hill Publishing Company, 1990).
J. Lindsay, Radiative Heat Transfer in Fluidised Beds, PhD. dissertation, Cambridge Univ., U.K., 1983.
S.E. Tung, T.Z. Chaung, P.K. Sharma, J. Hodges and J.F. Louis, Char Combustion in the Freeboard Region, 6th Int. Conf. on Fluidized Bed Combustion, Atlanta, USA (1980).
P.M. Walsh, A. Dutta, and J.M. Beer, Char Combustion in the Freeboard Above a Fluidized Bed Burning a High Volatile Bituminous Coal, 20th Symp. (Int.) on Combustion, The Combustion Institute, Pittsburgh, USA (1984).
O.A. Hougen, K.M. Watson and R.A. Ragatz, Chemical Process Principles (John Wiley, 1976).
R.H. Essenhigh, Combustion and Flame Propagation in Coal Systems: A Review, 16th Symp. (Int.) on Combustion, The Combustion Institute, Pittsburgh, USA (1977).
J.B. Howard, Fundamentals of Coal Pyrolysis and Hydropyrolysis: in Chemistry of Coal Utilization, 2nd Supplementary Volume (John Wiley, 1981, pp. 665-784).
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