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Abstract

A method and apparatus for producing clean, sweet, fuel gas for use in a combustion process and for producing other useful products by processing a waste stream from digestion of lignocellulosic material. Essentially, the waste stream is partially oxidized to form hot gases and molten salts. The hot gases and molten salts are then cooled using a quench liquor to form quenched gas and carbonate liquor. Particles are removed from the quenched gas to form a raw fuel gas, preferably by subjecting the quenched gas to a multi-step fume reduction process which includes heat extraction from the quenched gas to reduce particulate load and water content of the quenched gas to form a low fume fuel gas. H.sub.2S is removed from the low fume fuel gas using an H.sub.2S removal process which is more selective for H.sub.2S than it is for CO.sub.2, the removing step forming clean, sweet, fuel gas and acid gases. The clean, sweet, fuel gas may be conveyed to a combustion process, advantageously a gas turbine/electric generator couple and possibly to a heat recovery steam generator, and/or it may undergo further processing to form other useful products. Likewise, the acid gases can be processed to form additional useful products. The optional multi-step fume reduction process passes the quenched fuel gas through a first venturi scrubber, an electrostatic agglomerator, and a second venturi scrubber in series.

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First Claim