Method of separating acid gases, particularly carbon dioxide, from methane by the addition of a light gas such as helium
AssigneeExxon Production Research Company
InventorsJaime A. Valencia, Robert D. Denton
Life of this patent
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Abstract
A method of separating acid gases, particularly carbon dioxide, from methane by cryogenic distillation. The method includes the step of adding helium to the stream to be separated to increase the critical pressure of the methane-carbon dioxide present. The cryogenic distillation tower may then be operated at a higher pressure and without the formation of solid carbon dioxide.
Claims17
A method for separation of a feedstream containing methane and carbon dioxide in a cryogenic distillation tower without producing solid carbon dioxide comprising the steps of:
- introducing a diluent stream containing helium into said feedstream to produce a tower feedstream, said helium being introduced in amounts sufficient to raise the critical pressure of the resulting tower feedstream enough to preclude formation of solid carbon dioxide within said tower, and
- distilling said tower feedstream to produce an enriched carbon dioxide bottoms stream containing a major portion of the carbon dioxide in the feedstream and an enriched methane overhead stream containing substantially all of said helium.
A method for the separation of a feedstream containing methane and carbon dioxide in a cryogenic distillation tower without producing solid carbon dioxide comprising the steps of:
- cooling said feedstream by heat exchange,
- expanding said feedstream through expansion means,
- introducing a diluent stream containing helium to said feedstream in amounts sufficient to raise the critical pressure of the resulting tower feed enough to preclude formation of solid carbon dioxide within said tower,
- distilling said tower feed in a cryogenic distillation tower wherein at least a portion of said distillation tower is operated at a pressure higher than the critical pressure of the carbon dioxide and methane mixture contained therein calculated without the inclusion of helium to produce a bottoms stream containing a major portion of the carbon dioxide in said feedstream and an overhead stream containing a major portion of the methane in said feedstream,
- condensing at least a portion of said overhead stream and recycling the condensed overhead stream as reflux in said distillation tower,
- separating the remaining uncondensed portion of said overhead stream into a helium gas recycle stream and methane product stream, and
- compressing at least a portion of said helium gas recycle stream for mixing with said feedstream as said diluent stream.
Dependencies are inferred from the claim text.