Process and apparatus for liquefaction of CO2
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorMathieu Leclerc
Life of this patent
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Abstract
In a process of liquefaction and subcooling of a stream rich in CO2, the stream is liquefied by a closed cycle of refrigerant and subcooled by heat exchange with three streams of liquid CO2 at different pressures.
Claims13
A process for the liquefaction and subcooling of a stream rich in CO2 containing at least 95 mol % of carbon dioxide comprising the following steps:
- i. liquefying the stream rich in CO2 at a subcritical pressure greater than 48 bars abs, through an indirect heat exchange in a heat exchanger having a hot end and a cold end with an at least partially liquid stream of a refrigerant different from CO2 at a first pressure greater than 4 bara in which the liquid stream of refrigerant different from CO2 vaporizes to form a gaseous stream of refrigerant different from CO2 at the first pressure and the CO2-rich stream liquefies to form a CO2-rich liquid stream at a subcritical pressure,
- ii. subcooling the CO2-rich liquid stream or a fluid formed by separating the CO2-rich liquid stream, through indirect heat exchange in the heat exchanger with at least three other liquid streams rich in CO2 which each vaporize at a different pressure,
- iii. compressing the gaseous stream of refrigerant different from CO2 or a stream formed by separating said gaseous stream of refrigerant different from carbon dioxide, the compression taking place in a compressor from the first pressure to a second pressure greater than the first pressure in order to obtain a gas stream of refrigerant different from CO2, at the second pressure in a single compression stage, no gas flow being sent to an intermediate level of the compressor
- iv. condensing the gaseous stream of refrigerant different from CO2 at the second pressure or a stream resulting therefrom in order to obtain a liquid stream of ammonia at the second pressure
- v. cooling the refrigerant liquid stream to the second pressure in the heat exchanger and
- vi. expanding either the cooled liquid stream of refrigerant different from CO2 at the second pressure or a stream formed by separating the liquid stream of refrigerant different from CO2 up to the first pressure in order to obtain the at least partially liquid stream of refrigerant different from CO2 up to a single pressure which is the first pressure.
An apparatus for liquefying and subcooling a stream rich in CO2 containing at least 95 mol % of carbon dioxide comprising a heat exchanger having a hot end and a cold end, a means for sending the stream rich in CO2 at a subcritical pressure greater than 48 bar abs, liquefy through indirect heat exchange in the heat exchanger with an at least partially liquid stream of a refrigerant different from CO2 at a first pressure greater than 4 bara in which the liquid stream of refrigerant different from CO2, vaporizes to form a gaseous stream of refrigerant different from CO2 at the first pressure and the stream rich in CO2 liquefies to form a CO2-rich liquid stream at subcritical pressure, a means for subcooling the CO2-rich liquid stream or a fluid formed by separating the CO2-rich liquid stream, through an exchange of indirect heat in the heat exchanger with at least three other liquid streams rich in CO2 which each vaporize at a different pressure, therefore at at least three different pressure levels, a compressor for compressing the gaseous stream of refrigerant different from CO2 or a stream formed by separating this gaseous stream, the compression taking place in the compressor from the first pressure to a second pressure greater than the first pressure in order to obtaining a gas stream of refrigerant different from CO2 at the second pressure in a single compression step, no gas flow being sent to an intermediate level of the compressor, a means for condensing the gas stream of refrigerant different from CO2 at the second pressure or a current coming from it in order to obtain a liquid stream of ammonia at the second pressure, a means for sending the liquid stream of condensed refrigerant at the second pressure to cool in the exchanger heat and a means for expanding either the cooled liquid stream of refrigerant different from CO2 to the second pressure or a stream formed by separating the liquid stream of refrigerant different from CO2 to the first pressure in order to obtain the at least partially liquid stream of refrigerant different from CO2 up to a single pressure which is the first pressure.
Dependencies are inferred from the claim text.