Method and apparatus for separating gases
First Claim
1. A method of removing a gas dissolved in a liquid under pressure, said method comprising:
- combining a gas comprising at least one acidic gas with a liquid under pressure in order to form a pressurized liquid having at least one acidic gas dissolved therein;
wherein the pressurized liquid comprises a solvent and the solvent preferentially absorbs the at least one acidic gas,reducing the pressure on said liquid at a first expansion ratio, a first portion of said gas being thereby released from said liquid;
drawing off said first portion of said gas from said liquid;
reducing the pressure on said liquid at a second expansion ratio greater than said first expansion ratio, a second portion of said gas being thereby released from said liquid;
drawing off said second portion of said gas from said liquid; and
reducing the pressure on said liquid at a third expansion ratio greater than said second expansion ratio, a third portion of said gas being thereby released from said liquid;
and wherein expansion ratio Rn is defined as Pn-1/Pn and Pn-1 is the absolute pressure of the gas at a preceding stage and Pn is the absolute pressure of the gas at a subsequent stage n.
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Accused Products
Abstract
A method and apparatus for removing carbon dioxide from a synthesis gas stream containing hydrogen is disclosed. The method includes absorbing the carbon dioxide using a physical solvent under high pressure and then liberating the carbon dioxide in a series of expansion stages where the pressure on the solvent is reduced. The expansion ratio increases with each expansion stage. The apparatus includes expansion stages having throttling devices and expansion tanks operated at increasing expansion ratios. Carbon dioxide is liberated in this manner so as to minimize the energy required compress for transport via a pipe line for sequestration of the gas. Sequestration of the carbon dioxide is preferred to atmospheric venting to curb the release of greenhouse gases.
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Citations
24 Claims
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1. A method of removing a gas dissolved in a liquid under pressure, said method comprising:
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combining a gas comprising at least one acidic gas with a liquid under pressure in order to form a pressurized liquid having at least one acidic gas dissolved therein;
wherein the pressurized liquid comprises a solvent and the solvent preferentially absorbs the at least one acidic gas,reducing the pressure on said liquid at a first expansion ratio, a first portion of said gas being thereby released from said liquid; drawing off said first portion of said gas from said liquid; reducing the pressure on said liquid at a second expansion ratio greater than said first expansion ratio, a second portion of said gas being thereby released from said liquid; drawing off said second portion of said gas from said liquid; and reducing the pressure on said liquid at a third expansion ratio greater than said second expansion ratio, a third portion of said gas being thereby released from said liquid; and wherein expansion ratio Rn is defined as Pn-1/Pn and Pn-1 is the absolute pressure of the gas at a preceding stage and Pn is the absolute pressure of the gas at a subsequent stage n. - View Dependent Claims (2, 22, 23, 24)
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3. A method of removing a gas dissolved in a liquid under pressure, said method comprising:
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providing pressurized liquid having a gas comprising carbon dioxide dissolved therein;
wherein the liquid comprises a liquid physical solvent and the solvent absorbs carbon dioxide,reducing the pressure on said liquid in a product recovery pressure reduction stage and a plurality of subsequent pressure reduction stages beginning with a first subsequent pressure reduction stage, wherein each subsequent pressure reduction stage after said first subsequent pressure reduction stage occurs at an expansion ratio, in absolute pressure, greater than the pressure reduction stage which preceded it, a portion of said gas being released from said liquid at each pressure reduction stage. - View Dependent Claims (4, 5)
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6. A method of removing carbon dioxide gas from a gas mixture comprising hydrogen and carbon dioxide, said method comprising:
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bringing said gas mixture into contact with a liquid physical solvent under pressure, said solvent preferentially absorbing carbon dioxide gas from said gas mixture into the liquid; reducing the pressure on said solvent in a product recovery pressure reduction stage; further reducing the pressure on said solvent in a plurality of subsequent pressure reduction stages beginning with a first subsequent pressure reduction stage, wherein each subsequent pressure reduction stage after said first subsequent pressure reduction stage occurs at an expansion ratio greater than the preceding pressure reduction stage wherein a portion of said carbon dioxide gas absorbed by said solvent being released from said solvent at each pressure reduction stage, and wherein expansion ratio Rn is defined as Pn-1/Pn and Pn-1is the absolute pressure of the gas at a preceding stage and Pn is the absolute pressure of the gas at a subsequent stage n. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification