Patent ID: 8747806

Claim:
A process for producing hydrogen comprising the steps of: (i) passing a hydrocarbon feed though one or more purification sorbents to generate a purified hydrocarbon stream, (ii) combining steam with the purified hydrocarbon and passing the hydrocarbon/steam mixture adiabatically through a bed of steam reforming catalyst disposed in a pre-reformer vessel to generate a pre-reformed gas mixture, (iii) passing the pre-reformed gas mixture through externally-heated catalyst filled tubes in a fired steam reformer to generate a crude synthesis gas mixture comprising hydrogen, carbon monoxide, carbon dioxide and steam, (iv) passing the crude synthesis gas mixture through one or more beds of water-gas shift catalyst in one or more shift vessels to generate a shifted synthesis gas mixture, (v) passing the shifted synthesis gas mixture to a membrane shift reactor containing a bed of water-gas shift catalyst and a CO 2 -selective membrane, in which the shifted synthesis gas mixture is subjected to the water-gas shift reaction over the water-gas shift catalyst, and carbon dioxide is separated from the resulting shifted gas mixture by the membrane, thereby generating a hydrogen-enriched gas mixture, (vi) cooling the hydrogen-enriched gas mixture to below the dew point and separating off the condensate to generate a de-watered hydrogen-enriched gas mixture, (vii)passing the de-watered hydrogen-enriched gas mixture to one or more stages of CO 2 separation in pressure-swing absorption apparatus, to generate a pure hydrogen stream and a purge gas stream, and (viii) recycling at least a portion of the purge gas stream as fuel to the fired steam reformer or to the hydrocarbon feed or purified hydrocarbon feed streams.