Pinch Point Analysis of Heat Exchangers for Supercritical Carbon Dioxide with Gaseous Admixtures in CCS Systems

Carbon dioxide (CO2) captured in carbon dioxide capture and storage (CCS) processes is transported and stored in a supercritical state. Heat exchangers, especially recuperators, with CO2 on both the hot and the cold side are often impacted by the occurrence of a pinch point, that is, area of closest approach between hot and cold temperature curves. CO2 in CCS systems is not pure, and even small amount of admixtures can have a significant effect on the location and impact of the pinch point, on heat transfer properties and exchanger sizing. This work investigates the effects of several admixtures on these parameters. It is found that these admixtures may have a slightly positive effect on recuperative heat exchangers. However, these admixtures also result in a significant size increase of CO2 coolers.