Математическое моделирование ступенчатой газификации угля в плотном слое

И.Г. Донской

doi:10.18321/

Authors

I.G. Donskoy Melentiev Energy Systems Institute of Siberian Branch of the Russian Academy of Sciences, Lermontova st. 130, 664033, Irkutsk

DOI:

https://doi.org/10.18321/

Keywords:

mathematical model, process, reactor, gasification

Abstract

The paper devoted to development of staged fixed bed coal gasification mathematical model. Staged gasifi-cation is a process with fuel conversion dissection into more than one step. In this work fuel consecutive pyrolysis (semicoking) and gasification process is concerned. Products of pyrolysis gas combustion are used as gasification agent. Heat needed for coal pyrolysis is produced by output syngas portion combustion. Such a process allow to produce tar-free syngas (for tar species burning after pyrolysis stage) and therefore to avoid expensive gas cleaning systems using. In connection with these advantages it is important to have a calculation tool for staged gasification process numerical research and optimization. There is recycling flow in staged gasification process scheme, so solution is found by the means of iterative procedure that specifies regime parameters stationary values. Raw coal pyrolysis and semicoke gasification reactors are calculated using previously developed fixed bed coal thermochemical conversion model. Gas combustion is supposed to achieve equilibrium for constant pressure and enthalpy. Mathematical model developed was applied to investigate controlling parameters influence. These parameters are syngas recycling and pyrogas combustion oxidizer excess coefficients. Calculation results show that there are ranges of the parameters values where stage gasification cold gas efficiency is slightly sloping function of them. Recycling coefficient decreasing lower than optimal value (6-7%) results in the lack of heat for pyrolysis and sharp process efficiency drop. By increasing of this parameter higher than 15% overall oxidizer excess rises so efficiency drops too. Pyrogas combustion oxidizer excess varying in a wide range (1-1,8) have no impact on process efficiency owing to useful unnecessary oxidizer consumption in gasification reactor.

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