Procédé de production de l'hydrogène.

摘要

In the production of hydrogen from hydrocarbons by the steps of reforming with steam and shift conversion, an improvement is effected by maintaining a steam-to-carbon ratio of 3 to 7 and a pressure of 300 to 700 p.s.i.a. in the reformer, converting 50 to 85% of the hydrocarbons to hydrogen in the reforming step, removing carbon oxides and steam from the process stream and cryogenically separating unconverted hydrocarbons from hydrogen to give 96% to 99.5% pure hydrogen. Contaminated process condensate (principally dissolved CO2, H2 and hydrocarbons), obtained after shift conversion, may be vaporized and recycled to the reformer. Low-purity hydrogen from an extraneous source may be purified by addition to the process stream prior to cryogenic separation. As shown, hydrocarbon and steam are preheated, e.g. to 750 DEG F., and fed to reformer R-1, inlet pressure being e.g. 500 p.s.i.g. and outlet temperature being e.g. 1480 DEG F. R-1 exit gases are cooled to e.g. 700 DEG F. in B-2 before entry to shift converter C-1. Contaminated process condensate may be evaporated in boilers B-2 and B-3. Two or more catalysts may be used at different temperatures in the shift conversion stage. C-1 exit gases pass through boiler B-3, heat exchanger E-1, and boiler B-4, in which spent solutions from the CO2 removal stage are regenerated by heat exchange. Condensate is collected in separator S-1 at e.g. 260 DEG F. from the process stream, which is further cooled to ambient temperature in heat exchanger E-2, more condensate being removed in separator S-2. Carbon dioxide is removed from the process stream before unconverted hydrocarbons are separated in the cryogenic unit at e.g. -270 DEG F. to -290 DEG F. and 250 to 650 p.s.i.a. If the hydrogen is required for high pressure hydrogenation, compression to e.g. 650 to 1500 p.s.i.a. may be effected prior to the cryogenic step. Carbon monoxide may be separated in the cryogenic unit to give hydrogen containing not more than 100 p.p.m. carbon monoxide. Purge gas or recycle gas from a hydrogenation unit may be added to the process stream either before or after the CO2 removal stage.