Modeling of fixed bed Char combustion process

Bir sabit yataktaki char yığınının pseudo-kararlı durum yanması incelenmiştir. Char'ın sabit karbondan oluştuğu kabul edilmiştir. Bu model, karbonun oksijen ve karbon-dioksit ile heterojen reaksiyonlarını dikkate almaktadır. Sabit yatak içerisindeki ısı ve kütle aktarımını yöneten denklemler, değişken sıcaklık şartlarında, char-gaz reaksiyonlarına dayanılarak elde edilmişlerdir. Char yarıçap denklemi ile ısı ve kütle aktarımı için elde edilen nonlineer adi diferansiyel denklemler çifti, yarı-kapalı Üçlü Bant Matris Algoritması kullanılarak eş-zamanlı çözülmüşlerdir. Bunun yanı sıra, char tüketimi için dönüşüm zamanı, "Simpson" sayısal integrasyon tekniği kullanılarak hesaplanmıştır. Katı debisinin hem dönüşüm zamanına hem de dönüşüm oranına olan etkileri incelenmiştir.

Sabit yatak Char yanma prosesinin modellenmesi

The pseudo-steady state combustion of char lump in a fixed bed is investigated. Char is assumed to be consisting of fixed carbon. The model considers the heterogeneous reactions of carbon with oxygen and carbon dioxide. Equations governing heat and mass transfer in the fixed bed are derived based on char-gas reactions under non-isothermal conditions. The char radius equation and coupled-nonlinear ordinary differential equations obtained for heat and mass transfer in the bed are solved simultaneously using semi-implicit Tri-diagonal Matrix Algorithm (TDMA). A Conversion time for the consumption of char is also computed by Simpson's rule of numerical integration technique. Effects of solid flow rate on both the conversion time and the conversion ratio are investigated.

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1.Kumplnsky, E. and Amundson, N.R., "Diffusion and Reaction in a Stagn; Boundary Layer about a Carbon Partiple. 8.," Ind.Eng.Chem.Fundam., 22, (71(1983).
2.Kumplnsky, E. and Amundson, N.R., "Diffusion and Reaction in a Stagnat Boundary Layer about a Carbon Particle. 8.a," Ind.Eng. Chem.Fundam., 23, : 37(1984).
3.Sotirchos, S.V. and Amundson, N.R., "Diffusion and Reaction in a Char Particle and in the Surrounding Gas Phase.Two limiting Models,'' Ind.Eng.Chem.Fundam., 23, 180-191(1984).
4.Sotirchos, S.V. and Amundson, N.R., "Diffusion and Reaction in a Char Particle and in the Surrounding Gas Phase.A Continuous Model,'' Ind.Eng.Chem.Fundam., 23, 191-201(1984).
5.Sotirchos, S.V. and Amundson, N.R., "Dynamic Behavior of a Porous C Particle Burning in an Oxygen-Containing Environment. Part I," AIChe Journal 30(4), 537-548(1984).
6.Sotirchos, S.V. and Amundson, N.R., "Dynamic Behavior of a Porous Char Particle Burning in an Oxygen-Containing Environment. Part II," AIC Journal, 30(4), 549-556(1984).
7.Gavalas, G., Noncatalytic Gas-Solid Reactions with Applications to Chat Combustion and Gas Desulfurizatiott Concepts and Design of Chemical Reactors, Edited by Whhaker, E. and Cassano, A.E., Gordon and Bre; Science Publishers, Volume 3, Chapter 3, Montreux, Switzerland (1986).
8.Bryıkoğlu, A., "Modeling of a Fixed Bed Reactor for Non-catalytic Solid gas Reactions," Journal of the Institute of Science and Technology, Gazi University, 14(3), 829-840(2001).
9.Ishida, M. and Wen, C.Y., "Analysis of Nonisothermal Moving Bed for Noncatalytic Solid-Gas Reactions," Ind.Eng.Chem.Process.Des. Develop., 1( (1971).
10.Ishida, M. and Wen, C.Y., "Effectiveness Factors and Instability in Solid-Gas Reactions," Chemical Engineering Science, 23, 125-137(1968)