Process for prevention of water build-up in cryogenic distillation column
AssigneeKoch Process Systems, Inc.
InventorRichard B. Hopewell
Life of this patent
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Abstract
A process by which a vapor side product stream is taken from the bottom section of a cryogenic distillation column, such as a propane or ethane recovery column, which process optionally employs a nonpolar liquid additive for use in the separation of acid gases from a hydrocarbon feed stream. The withdrawal of the vapor side stream prevents the build-up of water in the column which would ordinarily lead to free-water formation or the formation of solid hydrates in the cryogenic distillation column.
Claims20
In a process for the separation of a hydrocarbon and acid gas containing feed stream in a cryogenic distillation column, a zone of said column which is operated at a temperature of 60.degree. F. or less, wherein free water accumulates or forms hydrates in said column from water vapor in the feed stream during the cryogenic process, and which process comprises separating the said feed stream in said column into an overhead stream and a bottom stream, the improvement which comprises:
- withdrawing a hydrocarbon and acid gas vapor stream which stream is enriched in water vapor with respect to said feed stream, thereby preventing the excess accumulation of free water or the formation of hydrates in said cryogenic column.
In a cryogenic process of the separation of an acid gas containing hydrocarbon feed stream in a cryogenic distillation column, a zone of said column which is operated at a temperature of 60.degree. F. or less, where free water accumulates or forms hydrates in said column from water vapor in the feed stream and the feed stream contains more than about 5 ppm of water vapor during the cryogenic process, and which process comprises separating the said feed stream in said column into a carbon dioxide enriched overhead stream and a C.sub.2 or C.sub.3 + enriched bottom stream, the improvement which comprises:
- (a) withdrawing from said cryogenic distillation column a hydrocarbon and carbon dioxide gas vapor stream which is enriched in water vapor with respect to said feed stream and contains more than about 1000 ppm of water vapor and withdrawing the said vapor stream between the feed inlet of said column and the outlet of the bottom stream of said column at a location in said column wherein the water vapor concentration is about at the maximum concentration;
- (b) dehydrating the withdrawn vapor stream to a water vapor concentration of about or less than the water vapor concentration of the feed stream introduced into said column;
- and
- (c) recycling from about 0.5 to 5.0 moles of the dehydrated vapor stream per 100 moles of the feed stream into said column, thereby preventing the accumulation of free water or the formulation of hydrates in said column during the cryogenic process.
Dependencies are inferred from the claim text.