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US 12,735,325 B2Granted
Purge gas conditioning of NH3 plants
AssigneeStamicarbon B.V.
InventorsBarbara Cucchiella, Joey Dobree, Mahal Patel, Michael Mattis Carlos Verheijen, Rolf Sybren Postma
Life of this patent
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Abstract
Embodiments of the disclosure pertain to the conditioning of the purge gas stream in an NH3 synthesis plant comprising a water electrolysis unit to produce a H2 stream, ammonia synthesis loop, and a treatment section for treating purge gas at 10-70 bar(a) using scrubbing and membrane separation.
Claims22
A process for conditioning a purge gas stream in an ammonia synthesis plant comprising a water electrolysis unit to produce a H2 stream and an ammonia synthesis loop for reacting said H2 with an N2 feed, the process comprising:
- a) obtaining a purge stream from said ammonia synthesis loop, wherein said purge stream is gaseous and comprises N2, H2, NH3 and Ar;
- b) subjecting said purge stream to a treatment at a pressure of 10-70 bar (a) comprising scrubbing in a scrubber and membrane separation in a membrane separation unit to remove at least a part of the NH3 and at least part of the H2 from the purge gas stream, to provide a treated purge stream, a gaseous stream comprising H2 and a liquid stream, wherein the membrane separation uses a hydrogen-selective membrane having a permeate side and a retentate side, and comprises supplying a sweep gas comprising N2 at the permeate side of the membrane;
- and
- c) recycling the gaseous stream in part or entirely to the ammonia synthesis loop, wherein step a) comprises reducing the pressure of the purge stream from the pressure of the ammonia synthesis loop to a pressure in the range of 10 to 70 bar(a) with a pressure reducing element that comprises an ejector that also receives a gas stream that is obtained from a step of flashing a high pressure NH3 liquid stream in the ammonia synthesis plant.
1 more element
An ammonia synthesis plant comprising a water electrolysis unit to produce a H2 stream;
- an ammonia synthesis loop for reacting said H2 with an N2 feed and having an outlet for a gaseous purge stream;
- and a treatment section comprising a scrubber and a membrane separation unit for subjecting said purge stream to a treatment at a pressure of 10-70 bar(a) comprising scrubbing in the scrubber and membrane separation in the membrane separation unit to remove at least a part of the NH3 and at least part of the H2 from the purge gas stream, to provide a treated purge stream, a gaseous stream comprising H2 and a liquid stream, wherein the membrane separation unit comprises a hydrogen-selective membrane, a permeate side compartment and a retentate side compartment, and a supply for a sweep gas to the permeate side compartment;
- and
- a flow line for recycling the gaseous stream in part or entirely to the ammonia synthesis loop, wherein the ammonia synthesis plant comprises a flash vessel for flashing a high pressure NH3 liquid stream from the ammonia synthesis loop, which flash vessel has a gas outlet and a liquid outlet, wherein said gas outlet is connected to an ejector provided in the flow line for the purge stream from the ammonia synthesis loop to said treatment section.
1 more element
A method of modifying an ammonia synthesis plant comprising a water electrolysis unit to produce a H2 stream;
- an ammonia synthesis loop for reacting said H2 with N2 feed and having an outlet for a gaseous purge stream;
- wherein the method comprises:
- providing the plant with
- a section comprising a scrubber and a membrane separation unit for subjecting said purge stream to a treatment at a pressure of 10-70 bar(a) comprising scrubbing in the scrubber and membrane separation in the membrane separation unit to remove at least a part of the NH3 and at least part of the H2 from the purge gas stream, to provide a treated purge stream, a gaseous stream comprising H2 and a liquid stream, wherein the membrane separation unit comprises a hydrogen-selective membrane, a permeate side compartment and a retentate side compartment, and a supply for a sweep gas to the permeate side compartment;
- and
- a flow line for recycling the gaseous stream in part or entirely to the ammonia synthesis loop, wherein the ammonia synthesis plant comprises a flash vessel for flashing a high pressure NH3 liquid stream from the ammonia synthesis loop, which flash vessel has a gas outlet and a liquid outlet, wherein said gas outlet is connected to an ejector provided in the flow line for the purge stream from the synthesis loop to said treatment section.
3 more elements
Dependencies are inferred from the claim text.