Results from Trialling Aqueous NH₃ Based Post Combustion Capture in a Pilot Plant at Munmorah Power Station: Desorption

Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) and Delta Electricity have tested an aqueous ammonia based post combustion capture (PCC) process in a pilot plant at Munmorah black coal fired power station. This paper presents and discusses the experimental results obtained and primarily focuses on the desorption section.

A high purity of CO₂ product was obtained at the stripper gas outlet with the CO₂ volumetric concentration generally between 99–100% and the remainder being water and NH₃. An increase in stripper pressure/temperature can lead to a decrease in NH₃ concentration in the CO₂ product. The NH₃ concentration can be controlled within 200 ppm without wash at a stripper pressure of 850 kPa (the maximum pressure tested) at a stripper gas outlet temperatures of 20–25°C. The solid precipitation occurred in the stripper condenser and reflux lines. Due to the low ammonia content in the solution, CO₂ content in the solution was low and generally more than 50% of regeneration energy was used to heat up the solvent under the pilot plant conditions. The lowest regeneration energy obtained from the pilot plant trials is 4–4.2 MJ/kg CO₂ captured. The effect of various parameters including solvent flow-rate and stripper temperature/pressure in the solvent on the regeneration energy was investigated.