Ethane rejection utilizing stripping gas in cryogenic recovery processes
First Claim
1. A process for separation of a relatively hot, methane rich feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas containing primarily methane and ethane and a relatively less volatile fraction, the process comprising the steps of:
- cooling the feed gas;
expanding the feed gas to form an expanded portion containing liquid;
treating at least some of the expanded portion liquid in a fractionating column by flowing the expanded portion liquid downwardly in the column between a top and a bottom thereof in counter current fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms;
wherein the fractionating column includes a main reboiler which heats and vaporizes a portion of the liquids flowing down the fractionating column to thereby provide stripping vapors which flow up the column; and
wherein a portion of the relatively hot, methane rich feed gas entering the process is routed to a bottom section of the column to upset a normally existing vapor-liquid equilibrium and thereby strip out undesired ethane from the liquid.
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Accused Products
Abstract
A process is shown for separating a relatively hot feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas and a primarily liquid bottoms. The feed gas is cooled to partially condense the feed gas to form a liquid portion which is expanded and fed to a fractionating column. The expanded liquid portion flows down the column in countercurrent fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms. A side reboiler heats and vaporizes a portion of the liquids flowing down the fractionating column to provide stripping vapors which flow up the column. A portion of the relatively hot, methane rich feed gas entering the process is routed to the column at a selected location in order to raise the relative volatility of liquids near the bottom of the column, resulting in ethane rejection.
13 Citations
9 Claims
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1. A process for separation of a relatively hot, methane rich feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas containing primarily methane and ethane and a relatively less volatile fraction, the process comprising the steps of:
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cooling the feed gas; expanding the feed gas to form an expanded portion containing liquid; treating at least some of the expanded portion liquid in a fractionating column by flowing the expanded portion liquid downwardly in the column between a top and a bottom thereof in counter current fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms; wherein the fractionating column includes a main reboiler which heats and vaporizes a portion of the liquids flowing down the fractionating column to thereby provide stripping vapors which flow up the column; and wherein a portion of the relatively hot, methane rich feed gas entering the process is routed to a bottom section of the column to upset a normally existing vapor-liquid equilibrium and thereby strip out undesired ethane from the liquid. - View Dependent Claims (2, 3)
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4. A process for separation of a relatively hot, methane rich feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas containing primarily methane and ethane and a relatively less volatile fraction, the process comprising the steps of:
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cooling the feed gas; expanding the feed gas to form an expanded portion containing liquid; treating at least some of the expanded portion liquid in a fractionating column by flowing the expanded portion liquid downwardly in the column between a top and a bottom thereof in counter current fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms; wherein the fractionating column includes a main reboiler and at least one additional side reboiler which together heat and vaporize a portion of the liquids flowing down the fractionating column to thereby provide stripping vapors which flow up the column; and wherein a portion of the relatively hot, methane rich feed gas entering the process is routed through a branch conduit to the side reboiler to upset a normally existing vapor-liquid equilibrium and thereby strip out undesired ethane from the liquid. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification