Configuration and process for NGL recovery using a subcooled absorption reflux process
First Claim
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1. A plant comprising:
- a column comprising a rectification section and an absorption section, wherein the column is fluidly coupled to a first separator that is configured to separate a feed into a lean oil liquid and a vapor;
a turbo-expander configured to expand a first portion of the vapor and fluidly coupled to the column to provide the expanded first portion to the absorption section, and an exchanger fluidly coupled to the separator and configured to cool a second portion of the vapor wherein the exchanger is fluidly coupled to the column to provide the cooled second portion as a reflux to the rectification section;
a second separator that is configured to receive a cooled natural gas feed and to separate the cooled natural gas feed into a vapor portion of the natural gas, a liquid portion of the natural gas, and water, and wherein the feed of the first separator comprises at least some of the vapor portion of the natural gas;
a feed stripping column that is configured to receive the liquid portion of the natural gas, that is configured to form a bottom product comprising natural gas liquids, and that is configured to produce a stripping column overhead product that is optionally dried, and introduced into the column; and
wherein the exchanger is further configured to subcool the lean oil liquid to a temperature sufficient to condense and absorb carbon dioxide and C2 components in the column and to provide the subcooled lean oil liquid to the absorption section.
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Abstract
An NGL recovery plant includes a demethanizer (7) in which internally generated and subcooled lean oil absorbs CO2 and C2 from a gas stream (11), thereby preventing build-up and freezing problems associated with CO2, especially where the feed gas has a CO2 treatment at ethane recoveries above 90% and propane recoveries of at least 99%.
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Citations
18 Claims
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1. A plant comprising:
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a column comprising a rectification section and an absorption section, wherein the column is fluidly coupled to a first separator that is configured to separate a feed into a lean oil liquid and a vapor; a turbo-expander configured to expand a first portion of the vapor and fluidly coupled to the column to provide the expanded first portion to the absorption section, and an exchanger fluidly coupled to the separator and configured to cool a second portion of the vapor wherein the exchanger is fluidly coupled to the column to provide the cooled second portion as a reflux to the rectification section; a second separator that is configured to receive a cooled natural gas feed and to separate the cooled natural gas feed into a vapor portion of the natural gas, a liquid portion of the natural gas, and water, and wherein the feed of the first separator comprises at least some of the vapor portion of the natural gas; a feed stripping column that is configured to receive the liquid portion of the natural gas, that is configured to form a bottom product comprising natural gas liquids, and that is configured to produce a stripping column overhead product that is optionally dried, and introduced into the column; and wherein the exchanger is further configured to subcool the lean oil liquid to a temperature sufficient to condense and absorb carbon dioxide and C2 components in the column and to provide the subcooled lean oil liquid to the absorption section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of operating a plant, comprising:
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providing a column comprising a rectification section and an absorption section; separating a feed in a first separator into a lean oil liquid and a vapor; separating in a second separator a cooled natural gas feed into a vapor portion of the natural gas, a liquid portion of the natural gas, and water, and wherein the feed of the first separator comprises at least some of the vapor portion of the natural gas; separating in a feed stripping column the liquid portion of the natural gas into a bottom product comprising natural gas liquids and a stripping column overhead product, and introducing the stripping column overhead product into the column; dividing the vapor in a first portion and a second portion, wherein the first vapor portion is expanded in a turbo-expander and introduced into the absorption section, and wherein the second vapor portion is cooled and introduced into the rectification section as a reflux; and cooling the lean oil liquid and introducing the cooled liquid into the absorption section at a temperature sufficient to condense and absorb carbon dioxide and C2 components in the column to thereby reduce a carbon dioxide concentration in the rectification section of the column. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification