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Coal Cascade Utilization

Gasification of Coal and Char with Fuel Preoxidation

Our centre is devoted to gasification of coal and pyrolysis char of small sizes(e.g.,0-10 mm) to produce fuel gas or reduction gas. The involved innovation idea is to incorporate preoxidation into a fluidized bed gasifier to intensify the gasification reactions and also to remove the caking propensity of coal, if adopting the jetting preoxidation other than fluidized bed preoxidation. Currently, we are working more on the latter in a dual bed system. This is an advanced fluidized bed gasification technology merging the advantages of dual fluidized bed gasification and the so-called two-stage gasification that integrates usually a fixed bed (or screw) pyrolyzer and a downdraft fixed bed gasifier. We thus name the technology“fluidized bed two-stage gasification”. Indeed, this innovative design has developed further the fluldized bed gasification technologies to minimize the tar formation and also to improve the fuel adaptability for high-moisture coal like lignite. Via the fluidized bed two-stage gasification´╝îthe vapor of fuel drying and pyrolysis from the fluidized bed preoxidation can become the gasification agent in the integrated pneumatic bed gasifier. This thus reduces the external steam feed to raise the overall efficiency, while the tar from the preoxidation bed can be deeplv cracked in the concurrent upward flow of char and gas in the transport bed under catalysis of char.