US Patent 9205382 Carbon dioxide separation system

In the carbon dioxide separation system, a mixed gas having a carbon dioxide concentration of 3 to 75% is introduced into a primary carbon dioxide separation device equipped with a zeolite membrane for carbon dioxide separation to produce a primary permeated gas having a carbon dioxide concentration of 80% or more on the permeate side of the zeolite membrane and also reduce the carbon dioxide concentration of a primary gas on the non-permeate side of the zeolite membrane to 3 to 15%. Next, the primary gas on the non-permeate side is introduced into a secondary carbon dioxide separation device that employs an amine absorption method or a pressure swing adsorption (PSA) method to produce a secondary separated gas having a carbon dioxide concentration of 80% or more separated by the separation device and also produce a carbon-dioxide-removed gas having a carbon dioxide concentration of 2% or less.