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US 5,634,354 AGranted
Olefin recovery from olefin-hydrogen mixtures
AssigneeAir Products and Chemicals, Inc.
InventorsLee J. Howard, Howard C. Rowles
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AssigneeAir Products and Chemicals, Inc.
InventorsLee J. Howard, Howard C. Rowles
Estimating the term…
Olefins are recovered from thermally cracked gas or fluid catalytic cracking off gas by cooling the gas to condense a portion of the hydrocarbons, removing hydrogen from the noncondensed gas, and condensing the remaining hydrocarbons in a cold condensing zone using a dephlegmator which operates above about -166.degree. F. This mode of operation minimizes the amount of methane in the condensate which is further processed in demethanizer column(s) and permits the condensation of ethylene at warmer temperatures than possible using a partial condenser in the cold condensing zone. The use of a dephlegmator at temperatures above about -166.degree. F. minimizes or eliminates the formation and accumulation of unstable nitrogen compounds in the ethylene recovery system. Hydrogen is removed from the noncondensed gas in a process selected from polymeric membrane permeation, adsorptive membrane permeation, or pressure swing adsorption.
A method for the recovery of olefins from a feed gas containing olefins and hydrogen which comprises cooling and partially condensing the feed gas in a first condensing zone to yield a first vapor enriched in hydrogen and a first liquid enriched in olefins, introducing the first vapor into a hydrogen-olefin separation process and withdrawing therefrom a hydrogen-enriched stream and an olefin-enriched intermediate stream, introducing the olefin-enriched intermediate stream into a second condensing zone wherein the olefin-enriched intermediate stream is further cooled, partially condensed, and rectified in a dephlegmator, and withdrawing from the dephlegmator a second liquid further enriched in olefins and a second vapor depleted in olefins.
Dependencies are inferred from the claim text.