Process for producing hydrogen and method of retrofitting a hydrogen production unit

A process for the production of hydrogen, comprising the steps of:

• feeding a mixture of hydrocarbon and steam to a fired reformer containing a plurality of catalyst-containing reformer tubes to produce a crude synthesis gas;
• feeding a fuel to the shell-side of the fired reformer to provide heat for the steam reforming reactions taking place in the catalyst-containing reformer tubes;
• feeding the crude synthesis gas from the fired reformer to an autothermal reformer along with an oxygen-containing gas to produce a reformed synthesis gas;
• feeding the reformed synthesis gas to a water-gas shift unit to produce a hydrogen-enriched gas;
• feeding the hydrogen-enriched gas to a carbon dioxide removal unit and separating the hydrogen-enriched gas into a crude hydrogen stream and a carbon dioxide stream;
• feeding the crude hydrogen stream to a purification unit and separating the crude hydrogen stream into a hydrogen product stream and an off-gas stream;
• and
• feeding a portion of the crude hydrogen stream and/or a portion of hydrogen product stream as fuel to the shell-side of the fired reformer.

A method of retrofitting an existing hydrogen plant, said existing hydrogen plant comprising:

• a fired reformer containing a plurality of catalyst-containing reformer tubes and having a shell side to which fuel is fed, operable to produce a crude synthesis gas;
• a water-gas shift unit arranged to be fed with a crude synthesis gas recovered from the fired reformer, operable to produce a hydrogen-enriched gas;
• and
• a purification unit arranged to be fed with a hydrogen-enriched gas from the water-gas shift unit, operable to produce a hydrogen product stream and an off-gas stream;
• the method comprising the steps of:
• installing an autothermal reformer downstream from the fired reformer and upstream from the water-gas shift unit, arranged to be fed with an oxygen-containing gas and a crude synthesis gas from the fired reformer, operable to produce a reformed synthesis gas;
• installing a carbon dioxide removal unit downstream from the water-gas shift unit and upstream from the purification unit, arranged to be fed with a hydrogen-enriched gas from the water-gas shift unit, operable to produce a crude hydrogen stream and a carbon dioxide stream;
• providing means for feeding a crude hydrogen stream from the carbon dioxide removal unit to the purification unit;
• and
• providing means for feeding a portion of the crude hydrogen stream from the carbon dioxide removal unit and/or a portion of the hydrogen product stream from the purification unit as fuel to the shell-side of the fired reformer.