초록 ▼

An improved process is disclosed for argon recovery from an ammonia synthesis plant purge gas stream comprising hydrogen, nitrogen, argon, methane, and ammonia. This purge gas is conventionally subjected to ammonia absorption and a first membrane separation of hydrogen for recycle to the ammonia pla

An improved process is disclosed for argon recovery from an ammonia synthesis plant purge gas stream comprising hydrogen, nitrogen, argon, methane, and ammonia. This purge gas is conventionally subjected to ammonia absorption and a first membrane separation of hydrogen for recycle to the ammonia plant. The hydrogen depleted non-permeate gas stream from the first membrane separator, comprising the aforesaid four components, and any residual moisture from the ammonia absorption, is subjected, according to a first embodiment of the present invention, to the following steps: (i) Separation of methane and residual moisture and most of the nitrogen in the gas stream in a pressure swing adsorption system using molecular sieve or activated carbon material. (ii) Separation of most of the hydrogen in a second membrane separator. The separated hydrogen may be used as purge gas for regeneration of the pressure swing adsorption systems of step (i). (iii) Separation of the nitrogen and residual hydrogen by cryogenic distillation to obtain essentially pure liquid argon product. In a second embodiment, step (ii) above is eliminated and separation of hydrogen is accomplished by cryogenic separation in combination with step (iii). In a third embodiment, separation of most of the hydrogen is accomplished by metal hydride adsorption in place of membrane separation. The present process is equally applicable with minor modifications for the recovery of argon from ammonia synthesis plant purge gas streams, wherein PSA or cryogenic units are employed instead of the first membrane separator, in order to recover hydrogen for recycle to the ammonia synthesis plant.

대표청구항 ▼

A process for recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising the following steps: (i) passing said gas stream through a pressure swing adsorption means to separate essentially all of the methane and most of the nitrogen, thereby producing a product s

A process for recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising the following steps: (i) passing said gas stream through a pressure swing adsorption means to separate essentially all of the methane and most of the nitrogen, thereby producing a product stream comprising a predominant amount of argon; and (ii) passing said product stream to a means for separating out most of the hydrogen to produce a hydrogen depleted product; and (iii) passing said hydrogen depleted product stream to a cryogenic distillation means to produce an essentially pure argon final product by separating out the remaining hydrogen and nitrogen.