A non-isothermal model of a bubbling fluidised-bed coal gasifer

D.P. Ross, H.M. Yan, Z. Zhong, Dongke Zhang

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

A previous one-dimensional numerical isothermal model of a fluidised-bed coal gasifier has been further improved to consider the non-isothermal behaviour of gases and heat transfer mechanisms in the fluidised-bed. Comparisons were made with data simulating the performance of a full-scale fluidised-bed coal gasifier, a 2 MWth pilot plant and a laboratory-scale bed. Simulation results indicate that comparisons of overall carbon conversions, operating bed temperatures and individual gas species predicted from both the non-isothermal and isothermal models with experimental data are favourable. The temperature profile of the gas phase predicted from the non-isothermal model follows the trend of the bubble temperature due to a large majority of the product gas flowing through the bed as bubbles. The temperature of cold feed gas is predicted to experience a heating up period at the lower part of the bed and homogeneous combustion in the gas phase results in a peak temperature in the gas phase. As a consequence of the higher solid temperature predicted from the non-isothermal model than from the isothermal model, the final product gas molar flow rate and fractional carbon conversion due to gasification predicted from the non-isothermal model are all higher giving better agreeing results compared with experimental data than those predicted from the isothermal model. In addition, these comparisons show that improvement in the predictive capabilities of the model depends on ability to predict the product CO/CO2 ratio which is particularly important for low volatile coals or char.
Original languageEnglish
Pages (from-to)1469-1481
JournalFuel
Volume84
Issue number12-13
DOIs
Publication statusPublished - 2005

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