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°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°C.