System and method for purifying hydrogen, and system for producing hydrogen by water electrolysis

A method for purifying a feed stream comprising hydrogen, comprising:

• introducing the feed stream into a first dryer to produce a purified hydrogen stream;
• regenerating a desiccant in a second dryer using a first portion of the purified hydrogen stream, comprising:
• introducing the first portion of the purified hydrogen stream into a first gas channel of a first heat exchanger to heat the first portion of the purified hydrogen stream;
• introducing the first portion of the purified hydrogen stream after heating into the second dryer to regenerate the desiccant;
• and
• introducing a regeneration tail gas from the second dryer into a second gas channel of the first heat exchanger to exchange heat with the first gas channel of the first heat exchanger, wherein the first portion of the purified hydrogen stream is comprised in the regeneration tail gas.

A system for producing hydrogen by water electrolysis, comprising:

• a water electrolysis module for producing a feed stream comprising hydrogen;
• a deoxygenation module for removing oxygen from the feed stream;
• a drying module for removing water vaper from the feed stream, wherein the drying module comprises a first dryer and a second dryer;
• a regeneration cycle module for regenerating desiccants in the drying module, wherein the regeneration cycle module comprises a first heat exchanger having a first gas channel and a second gas channel;
• a first stream control module configured to introduce the feed stream into the deoxygenation module and the first dryer to produce a purified hydrogen stream;
• and
• a second stream control module configured to:
• introduce a portion of the purified hydrogen stream into the first gas channel of the first heat exchanger to heat the portion of the purified hydrogen stream;
• introduce the portion of the purified hydrogen stream after heating into the second dryer to regenerate a desiccant in the second dryer;
• and
• introduce a regeneration tail gas of the second dryer into the second gas channel of the first heat exchanger to exchange heat with the first gas channel of the first heat exchanger, wherein the regeneration tail gas comprises the portion of the purified hydrogen stream that passes through the second dryer.