Method for Separating a Carbon Dioxide-rich Gas by Partial Condensation and Permeation

Abstract

A carbon dioxide-rich gas is cooled in a first heat exchanger; the carbon dioxide-rich gas cooled in the first heat exchanger enters a first phase separator at a first temperature between −50° C. and −53° C.; a carbon dioxide-enriched liquid is drawn from the first phase separator and acts as product; a carbon dioxide-depleted gas from the first separator is reheated in the first exchanger to a second temperature between −35° C. and −45° C., without having been expanded downstream from the first phase separator and enters a permeation unit at the second temperature; the reheated gas is subjected to at least one permeation step in the permeation unit in order to produce at least two fluids which are then reheated in the first exchanger, the fluid from the permeation unit, reheated in the exchanger, which exits the permeation unit at the lowest temperature, being at a temperature of more than −54° C.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a §371 of International PCT Application PCT / FR2013 / 051620, filed Jul. 8, 2013, which claims the benefit of FR1256771, filed Jul. 13, 2012, both of which are herein incorporated by reference in their entireties.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates to a method for separating a gas rich in carbon dioxide by partial condensation and permeation.BACKGROUND[0003]A gas rich in carbon dioxide contains at least 65 mol %, or at least 80 mol % or even at least 90 mol % of carbon dioxide, on a dry basis.[0004]The gas rich in carbon dioxide contains at least one lighter gas, such as oxygen, nitrogen, carbon monoxide, hydrogen.[0005]Preferably, it contains less than 5 mol % of methane, or even less than 2 mol % of methane.[0006]All the percentages in this document relating to purities are molar percentages.[0007]The low temperature separation of a gas rich in carbon dioxide is particularly chosen as a m...

AI Technical Summary

Benefits of technology

[0024]It will be possible to repeat the intermediate warming operations as many times as possible in order to optimize the system.

[0025]Irrespective of the chosen solution, care will be taken to adapt the pressure drop in the exchangers in the passes of the permeate(s) of the membranes. Specificall

Problems solved by technology

The loss of pressure between the inlet gas of the membranes and the permeate involves a large temperature drop.

Furthermore, since the gas resulting from the condensation pot is at phase equilibrium and close to the triple point, an excessively large temperature drop could liquefy CO2, or even freeze it in the membrane, which could degrade its performances or even threaten its integrity.

Finally, i

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