Development of a Potassium Carbonate-based Absorption Process with Crystallization-enabled High-pressure Stripping for CO2 Capture: Vapor–liquid Equilibrium Behavior and CO2 Stripping Performance of Carbonate/Bicarbonate Aqueous Systems

Abstract

A novel absorption-based post-combustion CO2 capture process is being developed to reduce the energy use associated with CO2 stripping and compression. The process features the use of a concentrated potassium carbonate/bicarbonate (PCB) aqueous solution as a solvent and high-pressure CO2 stripping with a bicarbonate-dominant slurry enabled by crystallization of the CO2-rich solution. Vapor–liquid equilibrium data under the typical stripping conditions of the process were measured and CO2 stripping tests were performed under various pressures, temperatures, PCB concentrations, and CO2 loading levels using a bench packed-bed stripping column. The results showed that CO2 stripping with a highly concentrated, highly CO2-loaded PCB solution/slurry at a high temperature was favored to attain a high stripping pressure and a low water vapor-to-CO2 pressure ratio in the product gas stream. The total heat use measured for CO2 stripping with the PCB system was up to three times lower than that of the benchmark 5 M monoethanolamine system under favorable conditions.