Results from trialling aqueous ammonia-based post-combustion capture in a pilot plant at Munmorah Power Station: Gas purity and solid precipitation in the stripper

Australia's Commonwealth Scientific and Industrial Research Organisation and Delta Electricity have tested an aqueous ammonia-based post-combustion capture process in a pilot plant at the Munmorah black coal-fired power station. The results will be used to address knowledge gaps about the application of aqueous ammonia for post-combustion capture of CO2 and other pollutants in flue gas, and to explore potential applications of the ammonia process in the Australian power sector. This paper primarily focuses on gas purity and solid precipitation in stripper.A high purity of CO2 product was obtained at the stripper gas outlet. The CO2 volumetric concentration was generally between 99 and 100%, with the remainder being water and ammonia. The concentration of ammonia in the CO2 product stream can be lowered by increasing stripper pressure and temperature, increasing CO2 loading in the rich ammonia solvent, and decreasing ammonia concentration and stripper overhead condenser temperature. Solid precipitation occurred in the stripper condenser and reflux lines. XRD analysis revealed that solid ammonium bicarbonate precipitated in the stripper condenser and reflux lines. Based on our equilibrium-based model predictions, rich solvent split can potentially eliminate solid precipitation and reduce cooling duties during the aqueous ammonia based PCC processes.

► Results from an aqueous ammonia based PCC pilot plant under real flue gas conditions.
► A high purity of CO2 product (99–100 vol%) was obtained at the stripper gas outlet.
► Solid ammonium bicarbonate precipitated in the stripper condenser and reflux lines.
► Rich solvent split can potentially eliminate solid precipitation and reduce cooling duties.