Characteristics of CO2 hydrate formation/dissociation in H2O + THF aqueous solution and estimation of CO2 emission reduction by district cooling application

Abstract

CO2 conversion by gas hydrate is considered one of most practical technologies in the fields of Carbon Capture, Utilization and Storage (CCUS). In this study, the effects of hydrate formation pressure and concentration of tetrahydrofuran (THF) on the CO2 + THF hydrate formation and dissociation performance are investigated, and the reduction of CO2 emission by applying the CO2 + THF hydrate for district cooling system is also evaluated. The CO2 capture ratio tends to increase with increasing the hydrate formation pressure and THF concentration. It is found that the CO2 regeneration rate increases with decreasing the formation pressure and the increasing rate decreases with time. It is concluded that the optimum conditions for the CO2 + THF hydrate formation and dissociation are 1.5 MPa, THF 1.5 mol% to use hydrate slurry as the working fluid for district cooling application. Also, the dissociation enthalpy of CO2 + THF hydrate was measured by using the high pressure micro-differential scanning calorimeter. The cycle simulation of hydrate cooling system is conducted, and the COP is estimated as 11.55. Finally, it is estimated that 20,684 tons of CO2 emission could be reduced per year if the CO2 + THF hydrate technology is applied to the district cooling system of 51,600 RT.