System and method for rare gas recovery
AssigneePraxair Technology, Inc.
InventorHenry E. Howard
Life of this patent
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Abstract
A system and method for argon and nitrogen extraction and liquefaction from a low-pressure tail gas of an ammonia production plant is provided. The preferred tail gas of the ammonia production plant comprises methane, nitrogen, argon, and hydrogen. The disclosed system and method provides for the methane rejection via rectification and hydrogen rejection by way of a side stripper column or phase separator. The resulting nitrogen and argon containing stream is separated and liquefied in a double column distillation system.
Claims22
A method for recovering a rare gas from a pre-purified feed gas comprising hydrogen, nitrogen, methane, argon, and one or more rare gases, the method comprising the steps of:
- directing the pre-purified feed gas to a rectification column;
- separating the pre-purified feed gas in a rectification column to produce a methane-rich liquid column bottoms containing the one or more rare gases and an hydrogen-nitrogen rich gas overhead;
- conditioning the methane-rich liquid column bottoms containing rare gases to produce a stream having a vapor fraction greater than 90% and at or near saturation;
- directing the methane rich stream and a rare gas lean stream to an auxiliary wash/rectifying column, wherein the rare gas lean stream is a liquid stream extracted from the rectification column or a liquid nitrogen stream;
- rectifying the two phase methane rich stream and the rare gas lean stream to produce a liquid bottoms rare gas concentrate and a methane-rich overhead;
- and
- separating one or more rare gases from the liquid bottoms rare gas concentrate to produce a rare gas product stream.
(canceled)
(canceled)
A system for separating a pre-purified feed gas comprising hydrogen, nitrogen, methane, argon, and one or more rare gases, the system comprising:
- a refrigeration system configured to cool the pre-purified feed gas to a near saturated vapor state;
- a primary rectification column coupled to the refrigeration system and configured to receive the cooled feed gas and to separate the cooled feed gas to produce a methane-rich liquid column bottoms containing the one or more rare gases and a hydrogen-nitrogen gas overhead;
- a conditioning system configured to partially vaporize the methane-rich liquid column bottoms containing the one or more rare gases to produce a two phase methane rich stream having a vapor fraction greater than 90% and at or near saturation;
- an auxiliary wash/rectifying column coupled to the conditioning system and configured to receive the two phase methane rich stream and a rare gas lean stream, wherein the rare gas lean stream is a liquid stream extracted from the rectification column or a liquid nitrogen stream;
- wherein the auxiliary wash/rectifying column is further configured to rectify the two phase methane rich stream and the rare gas lean stream to produce a liquid bottoms rare gas concentrate and a methane-rich overhead;
- and
- a post-processing separation and purification system configured to recover the one or more rare gases from the liquid bottoms rare gas concentrate to produce a rare gas product stream.
Dependencies are inferred from the claim text.