Potassium Carbonate Slurry-Based CO2 Capture Technology

Carbonate slurry process is considered to be one of the potential technologies for large-scale CO2 capture from coal-based power stations, as it can reduce the participation of water in stripper. In this work, constant volume method was adopted to measure the CO2 loading in aqueous potassium carbonate solutions at the temperatures of 40, 70, and 120 degrees C for CO2 partial pressure from 0.4 to 240 kPa. Absorption heats of CO2 in aqueous solutions of K2CO3, MEA, and MDEA were measured and compared using true heat flow method. The cyclic CO2 equilibrium loading increases with K2CO3 concentration increase, which is a benefit for CO2 capture. However, the increased viscosity leads to a decrease of the apparent absorption rate. Absorption heat depends on temperature, K2CO3 concentration, and CO2 loading. Compared to MEA, potassium carbonate solution has a lower absorption heat. Generated potassium bicarbonate crystallization can enhance CO2 absorption but also increase absorption heat. Slurry desorption can reduce 34% regeneration energy and 37% cooling duty of CO2-rich gas compared to the traditional carbonate process without precipitation at the same regeneration condition of temperature elevation from 70 to 130 degrees C.