US 5,462,583 AGranted

Absorption process without external solvent

AssigneeAdvanced Extraction Technologies, Inc.

InventorsGlenn C. Wood, Yuv R. Mehra

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Abstract

An absorption process for separating a feed gas stream having components with a spectrum of volatilities including volatile (light) components, intermediate volatility components, and least volatile (heavy) components. The disclosed process includes the steps of: (1) contacting the feed gas stream with a liquid lean solvent stream in an absorber to produce a light product gas stream that is composed of predominantly light components and a rich solvent stream containing most of the intermediate and heavy components; (2) flashing the rich solvent stream at reduced pressure in a flash zone to produce an intermediate product gas stream composed predominantly of intermediate components and a lean solvent stream; (3) conveying the lean solvent stream from the flashing zone to the absorber, wherein the lean solvent is composed predominantly of heavy components taken from the feed; the process does not use an external lean solvent. The process is particularly useful for rejecting nitrogen from natural gas and for recovering hydrogen from refinery and petrochemical process off-gases.

Claims14

Dependent claims

A process for separating a feed gas stream consisting of components which have a spectrum of volatilities including most volatile (light) components, intermediate volatility components, and least volatile (heavy) components, comprising the steps of:

(a) cooling the feed gas stream in a feed gas cooler and separating a heavy component condensate form the feed gas;
(b) conveying a portion of the heavy component condensate produced in step (a) to an absorption zone, said portion of heavy component condensate being a liquid lean solvent;
(c) contacting the feed gas stream with the liquid lean solvent stream in the absorption zone to produce a light product gas stream and a rich solvent liquid stream so that the light product gas stream comprises the light components from the feed gas, and the rich solvent liquid stream comprises the lean solvent plus intermediate and heavy components that have been absorbed by the lean solvent in the absorption zone;
(d) flashing the rich solvent liquid stream form the absorption zone in a flashing zone to produce at lower pressure a flash gas stream and a lean solvent stream so that the flash gas (intermediate product) gas stream comprises the intermediate components form the feed gas, and the lean solvent consists essentially of heavy components supplied from the feed gas;
and
(e) conveying the lean solvent produced in step (d) to the absorption zone as the lean solvent stream in step (c).

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/206,420Filed 4 Mar 1994
Granted: 31 Oct 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification24 codes

B01D 53/14
Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g.…: by…
B01D 53/1493
By absorption: selection of liquid materials for use as absorbents
C01B 3/52
Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification: by contacting with liquids; Regeneration of used liquids
C07C 7/11
Purification; Separation; Use of additives: by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids