Coal Gasification in a Two-Stage Spouted Bed Reactor

Abstract

The application of the spouted bed technique to a coal gasifier has been studied in order to operate at the optimum temperature range of the gasification. The gasifier developed is composed of two parts. Jet-spouted bed reaction proceeds at the first stage in the lower part of the gasifier, and conventional spouted bed reaction at the second stage in the upper part of the gasifier. Regime maps of the jet spoutability and conventional spoutability in a column were determined.
Taiheiyo coal was gasified with oxygen-steam mixtures in the dry ash mode under atmospheric pressure at temperatures up to 1350K. The effects of the oxygen/coal ratio and coal feed rate on the gasification performance were investigated. As a result, it was found that both the carbon conversion and thermal efficiency were mainly affected by the oxygen/coal ratio. The fractional conversion of carbon was 0.93 and cold gas thermal efficiency was 0.74 at the oxygen/coal ratio of 0.87. The product gases contained about 43% hydrogen and 20-30% carbon monoxide.
The gasifier contains the jet-spouted bed where the partial combustion reaction mainly occurs so that the gasifier was able to be operated at around optimum gasification temperature as high as 1350K without clinkering troubles. The reactor has been demonstrated to be an efficient dry-ash coal gasifier for the production of good quality gases.