CO2 capture from natural gas in LNG production. Comparison of low-temperature purification processes and conventional amine scrubbing

Carbon Capture and Storage is a crucial mitigation strategy that aims at preventing the release of large quantities of CO2 into the atmosphere. More recently, studies on CCS integration with the LNG production, which requires a deep removal of CO2 to avoid its freezing, have begun. In this respect, the application of low-temperature CO2 removal processes is interesting: CO2 can be recovered in liquid phase under pressure, being suitable for direct pumping and transportation or for direct storage, at a cost lower than that required using traditional physical or chemical scrubbing units. The present chapter deals with an energy analysis based on the concept of equivalent methane aimed at comparing a conventional technology (MDEA scrubbing) with low-temperature ones (Ryan-Holmes process and dual pressure low-temperature distillation), taking into account the overall LNG production chain, where the low temperatures required in the purification step are synergistic with the LNG production.