Recovery and purification of hydrogen from refinery and petrochemical off- gas streams

摘要

A hydrogen-containing inlet gas stream is countercurrently extracted with lean solvent to produce an overhead stream of at least 90% purity hydrogen and a bottoms stream of rich solvent which is flashed in one to a plurality of stages. The flashed gas from at least the first stage, after compression, is recycled to the extracting step. The flashed gases from the remaining stages are recovered as fuel gas. When a hydrogen purity of more than 95% is needed, a minor portion of the stripped solvent from the last flashing stage is regenerated in a distillation column to form very lean solvent which is fed to the top of the extractor column while the major portion of the stripped solvent is fed to its middle.