Patent ID: 8038906

Claim:
A process for the adjustment of the composition of a synthesis gas produced in a high temperature downflow black liquor gasifier, comprising the steps of (a) generating a gasifier effluent stream from black liquor in said gasifier by means of 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 H 2 /CO ratio of between 0.9 and 1.25; (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 synthesis gas; (f) splitting and recycling individual or combinations of split streams of the processed synthesis gas from the synthesis section or the unprocessed synthesis gas to step (a) and/or step (b), wherein a by-product stream of CO 2 being further generated in step (e) is in part or completely recycled to step (a) and/or step (b).