Systems and methods for separating condensable vapors from light gases or liquids by recuperative cryogenic processes
Methods and systems of the current invention separate condensable vapors such as carbon dioxide from light gases or liquids in a mixed process stream. The separation is carried out in a cryogenic process using one or more external cooling loops (ECLs) that first cool down a mixed process stream containing condensable vapors and light gases or liquids, causing the condensable vapors to desublimate and form solids. Next, the solids are separated from the light gases or liquids, forming a solid stream and a light gas or liquid stream. Then the refrigerants of the ECL are cooled by warming the separated solid stream and light gas or liquid stream, efficiently recovering energy used in cooling and desublimating the condensable vapors.
1. A method for separating a condensable vapor from light gases or liquids by desublimating the condensable vapor, comprising:
(i) cooling a mixed process stream comprising the condensable vapor and at least one light gas or liquid to a temperature of T1 to cause the condensable vapor to desublimate, using a refrigerant of a cooling loop, the condensable vapor desublimating during heat exchange between the mixed process stream and the refrigerant of the cooling loop;
(ii) separating the desublimated condensable vapor from the light gas or liquid to form a solid stream and a light gas or liquid stream;
(iii) pressurizing the solid stream; and
(iv) cooling or transferring heat from the refrigerant of the cooling loop using at least a portion of the solid stream, thereby melting at least a portion of the solid stream to form a liquid stream.
2. The invention of claim 1 , wherein step (iv) further comprises condensing at least a portion of the refrigerant at a temperature in a range of 0-20° C. above the melting temperature of the solid stream at a pressure.
3. The invention of claim 1 , wherein step (iv) further comprises condensing at least one of the refrigerant at a temperature in a range of 0-5° C. above the melting temperature of the solid stream at a pressure.
4. The invention of claim 1 , wherein step (i) further comprises boiling at least a portion of the refrigerant at a temperature in a range of 0-20° C. below the desublimating temperature of the condensable vapor at a pressure.
5. The invention of claim 1 , further comprising expanding the refrigerant before using them to cool the mixed process stream and compressing the expanded refrigerant thereafter.