Review on cryogenic technologies for CO 2 removal from natural gas

CO 2 in natural gas (NG) is prone to condense directly from gas to solid or solidify from liquid to solid at low temperatures due to its high triple point and boiling temperature, which can cause a block of equipment. Meanwhile, CO 2 will also affect the calorific value of NG. Based on the above reasons, CO 2 must be removed during the NG liquefaction process. Compared with conventional methods, cryogenic technologies for CO 2 removal from NG have attracted wide attention due to their non-polluting and low-cost advantages. Its integration with NG liquefaction can make rational use of the cold energy and realize the purification of NG and the production of by-product liquid CO 2 . In this paper, the phase behavior of the CH 4 -CO 2 binary mixture is summarized, which provides a basis for the process design of cryogenic CO 2 removal from NG. Then, the detailed techniques of design and optimization for cryogenic CO 2 removal in recent years are summarized, including the gas-liquid phase change technique and the gas-solid phase change technique. Finally, several improvements for further development of the cryogenic CO 2 removal process are proposed. The removal process in combination with the phase change and the traditional techniques with renewable energy will be the broad prospect for future development.