Membrane-based process gas drying with low pressure gaseous streams system and method

A system for separating a gas mixture, the system comprising:

• a source of the gas mixture;
• a first membrane stage in fluid communication with the source of the gas mixture, the first membrane stage configured to separate the gas mixture into a first retentate stream and a first permeate stream;
• a first drying module in fluid communication with the first membrane stage, wherein the first drying module is designed to receive the first permeate stream and produce a dried gas stream from the first permeate stream;
• and
• a carbon dioxide recovery system downstream of the first drying module, wherein the carbon dioxide recovery system is configured to receive the dried gas stream and produce a sweep stream and a product stream.

A method for separating a gas mixture, the method comprising:

• providing the gas mixture comprising methane, carbon dioxide, and water;
• feeding the gas mixture to a first membrane stage to separate the gas mixture into a first retentate stream and a first permeate stream;
• feeding the first permeate stream to a membrane dryer to remove the water from the first permeate stream;
• and
• producing a dehydrated gas stream, wherein the dehydrated gas stream is imparted with a dewpoint of no more than about −20° C. to no less than about −75° C.