Process for the preparation of synthesis gas from black liquor

Abstract

A process for the adjustment of the composition of a synthesis gas produced in a high temperature black liquor gasifier. The process includes the steps of (a) generating a gasifier effluent stream from black liquor in the gasifier by a blast and optionally an atomising stream; (b) optionally quenching the gasifier effluent stream with a gas stream to form a gas quenched effluent stream; (c) quenching the gasifier effluent of step (a) or the gas quenched effluent gas stream of step (b) with a water stream to form a raw synthesis gas; (d) further cooling and cleaning and separating the raw synthesis gas to form a purified unprocessed synthesis gas with an appropriate H/CO ratio; (e) partly converting the purified synthesis gas to dimethyl ether in a synthesis section, producing at least a product stream of DME and a hydrogen rich purge stream of processed; (f) splitting and recycling individual or combinations of split streams of the processed or the unprocessed synthesis gas to step a and/or step (b); and recycling a by-product stream of CObeing further generated in step (e) in part or completely to step (a) and/or step (b).