PSA tail gas preheating
A process for improving the thermodynamic efficiency of a hydrogen generation system is provided. This includes producing a syngas stream in a reformer, wherein the reformer has a combustion zone. This also includes introducing a syngas stream into a pressure swing adsorption unit, thereby producing a product hydrogen stream and a tail gas stream. This also includes heating the tail gas stream by indirect heat exchange with a heat source, thereby producing a heated tail gas stream; and introducing the heated tail gas stream into the combustion zone.
1. A method of improving the thermodynamic efficiency of a hydrogen generation system, comprising;
producing a syngas stream in a reformer, wherein said reformer has a combustion zone;
introducing a syngas stream into a pressure swing adsorption unit, thereby producing a product hydrogen stream and a tail gas stream;
heating said tail gas stream by indirect heat exchange with a heat source, thereby producing a heated tail gas stream; and
introducing said heated tail gas stream into said combustion zone.
2. The method of claim 1 , wherein said heat source comprises the syngas stream.
3. The method of claim 2 , wherein said syngas stream has a temperature of between about 250 F and about 300 F.
4. The method of claim 1 , further comprising shifting carbon monoxide to carbon dioxide in a water gas shift reactor, thereby producing a shifted syngas stream, then introducing said shifted syngas stream into said pressure swing adsorption unit, wherein said heat source comprises said shifted syngas stream.
5. The method of claim 4 , wherein said shifted syngas stream has a temperature of between about 700 F and about 800 F.
6. The method of claim 1 , wherein said combustion zone generates a flue gas stream, further comprising recovering heat from said flue gas stream in a heat recovery steam generator, thereby producing a steam stream, wherein said heat source comprises said steam stream.
7. The method of claim 1 , further comprising introducing an outside steam stream from a source external to said hydrogen generation system, wherein said heat source comprises said outside steam stream.
8. The method of claim 1 , wherein said combustion zone generates a flue gas stream, wherein said heat source comprises said flue gas stream.