Method for liquefying a stream rich in CO2
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsMichael Tran, Mathieu Leclerc
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Abstract
In a method for liquefying a gas rich in carbon dioxide, the gas is compressed to a first pressure greater than its critical pressure in a compressor to form a compressed gas, the compressed gas is cooled through heat exchange with a refrigerant to a variable temperature to form a cooled compressed gas with a density between 370 and 900 kg/m3, the cooled compressed gas is cooled at supercritical pressure in a first heat exchanger to a temperature below the critical temperature, the gas cooled below the critical temperature is expanded to a second pressure between 45 and 60 bara to form a diphasic fluid which is separated in a phase separator to form a liquid and a gas, and a liquid portion originating from the phase separator provides cold to the first heat exchanger.
Claims13
A process for the liquefaction of a gas rich in carbon dioxide, the process comprising the steps of:
- i. compressing the gas to a first pressure greater than its critical pressure in a compressor to form a compressed gas;
- ii. cooling the compressed gas by heat exchange with a refrigerant having a variable temperature to form a cooled compressed gas with a density between 370 and 900 kg/m3;
- iii. cooling the cooled compressed gas at the supercritical pressure in a first heat exchanger down to a temperature below the critical temperature;
- iv. expanding the gas cooled below the critical temperature to a second pressure between 45 and 60 bara to form a liquid or a two-phase fluid;
- wherein a part of the liquid or of the two-phase fluid from step iv) supplies cold to the first heat exchanger;
- and
- where in the part of the liquid or of the two-phase fluid from step iv) is subcooled to form a subcooled liquid:
- wherein, if the temperature of the refrigerant of step ii) lessens, the first pressure is reduced and/or,
- if the temperature of the refrigerant of step ii) increases, the first pressure is increased, and/or
- if the temperature of the refrigerant of step ii) lessens, the flow of liquid or of two-phase fluid sent to the first heat exchanger is reduced and/or,
- if the temperature of the refrigerant of step ii) increases, the flow of liquid or of two-phase fluid sent to the first heat exchanger is increased,
- wherein the first pressure is regulated in order to have one of N pressures, N being an integer between 2 and 5, whatever the temperature of the refrigerant.
A process for the liquefaction of a gas rich in carbon dioxide, the process comprising the steps of:
- i. compressing the gas to a first pressure greater than its critical pressure in a compressor to form a compressed gas;
- ii. cooling the compressed gas by heat exchange with a refrigerant having a variable temperature to form a cooled compressed gas with a density between 370 and 900 kg/m3;
- iii. cooling the cooled compressed gas at the supercritical pressure in a first heat exchanger down to a temperature below the critical temperature;
- iv. expanding the gas cooled below the critical temperature to a second pressure between 45 and 60 bara to form a liquid or a two-phase fluid;
- wherein a part of the liquid or of the two-phase fluid from step iv) supplies cold to the first heat exchanger;
- and
- wherein a part of the liquid or of the two-phase fluid from step iv) is subcooled to form a subcooled liquid:
- wherein, if the temperature of the refrigerant of step ii) lessens, the first pressure is reduced and/or,
- if the temperature of the refrigerant of step ii) increases, the first pressure is increased, and/or
- if the temperature of the refrigerant of step ii) lessens, the flow of liquid or of two-phase fluid sent to the first heat exchanger is reduced and/or,
- if the temperature of the of refrigerant of step ii) increases, the flow of liquid or of two-phase fluid sent to the first heat exchanger is increased,
- wherein, during a first period, the refrigerant is at an average temperature of T° C. and, during a second period, the refrigerant is at an average temperature of T+20° C., such that the density of the liquid from step iv) or of the liquid fraction of the two-phase fluid during the first period differs from that during the second period only by at most 100 kg/m3.
Dependencies are inferred from the claim text.