about 45 co 2 the second solvent portion 32 b pools at the bottom of first flash tank 76 a control valve 80 first control valve responsive to a liquid level sensor 82 controls the liquid level in first flash tank 76 and controllably feeds second solvent portion 32 b into a second flash tank 84 which is slightly above atmospheric pressure the pressure drop from flash tank 76 to flash tank 84 causes more co 2 to escape from the second solvent portion 32 b that co 2 is surplus as it is not needed for stripping trace contaminants from the first solvent portion 32 a in third absorber 16 thus that portion of the co 2 can be directly vented to atmosphere via a vent line 86 if that co 2 were not vented to atmosphere but instead directed into third absorber 16 the surplus co 2 would create an unnecessary incineration load on an incinerator 88 which will be explained later another control valve 90 second control valve responsive to a liquid level sensor 92 in a downstream third flash vessel 94 controls the liquid level in third flash tank 94 and controllably feeds the second solvent portion 32 b into third flash tank 94 a compressor 96 maintains third flash tank 94 at about a 4 to 5 psia negative gage pressure of about u2212 9 to u2212 10 psig which cause additional co 2 to escape from the second solvent portion 32 b this additional co 2 is later used in third absorber 16 to remove the trace contaminants from.