Regeneration of carbonated aqueous ammonia solution used for CO2 capture in soda ash production

Aqueous ammonia is an alternative absorption solution for CO2 capture, but its use is associated with several operational problems, mainly due to its volatility and the possibility of ammonium salt deposition.This paper presents the results of bench-scale studies on regenerating carbon dioxide-saturated ammonia solutions taken from the crude soda plant. This study is a continuation of research aimed at reducing CO2 emissions in the soda ash industry by using process solutions for carbon dioxide absorption. The study investigated the feasibility of regenerating the process solutions currently used for CO2 capture in a pilot absorber. The study determined the energy required for regeneration at different solution flow rates (20–60 l/h) and identified operational issues associated with the process. Additionally, a process modification was proposed, which involves adding a cooler to the upper part of the column.The desorption energy ranged from 37 to 181 kJ/molCO2 and the lowest heat duty (gross) was 7.2 MJ/kgCO2. The solution regeneration efficiencies obtained were comparable to other data from the pilot plant. It was found that an internal regenerator condenser can provide better process control than an overhead condenser. However, regular flushing will be required for continuous operation.