Patent ID: 8790617

Claim:
A process for producing hydrogen from a hydrocarbon feed and steam, comprising: A. a step for producing a synthesis gas in a unit for steam reforming the hydrocarbon feed in the presence of steam, with a fuel providing the heat necessary for the reaction; B. a step for steam converting synthesis gas obtained in the preceding step, producing a stream of hydrogen containing methane and carbon dioxide; C. a step for capturing carbon dioxide present in the stream obtained from the steam converting step in order to separate the carbon dioxide from the stream of hydrogen; D. a step for capturing and recycling impurities present in the stream of hydrogen to the steam reforming step (A), wherein step (D) is carried out in an adsorption unit comprising at least two adsorbers and comprises at least one of the following successive phases: i adsorbing the impurities on the first adsorber; ii regenerating the first adsorber and adsorbing the impurities on the second adsorber comprising the following steps: isolating the adsorber when it is saturated and bringing the second adsorber on-line; flushing the first adsorber with a stream of a hydrocarbon and heating the first adsorber by exchange with steam, to a temperature which is at least 20° C. higher than the steam condensation temperature and wherein the stream of a hydrocarbon and the steam which heats the adsorber both feed the steam reforming unit; regenerating the heated adsorber and desorbing the impurities by circulating steam superheated by at least 20° C. prior to being passed to the steam reforming unit; eliminating steam present in the regenerated adsorber by flushing the adsorber with a stream of purified hot hydrogen which is at a temperature of at least 20° C. higher than the condensation temperature of steam at the operating pressure; flushing the adsorber freed of steam with a stream of purified cold hydrogen which is at a temperature of 20° C. to 100° C.