The absorption rate of CO2 by aqueous ammonia in a packed column

The absorption of carbon dioxide into aqueous ammonia solution using packed column was studied experimentally. The overall absorption rate (Φ) and the volumetric overall mass transfer coefficient (KGaV) were investigated. The overall absorption rate (Φ) varies with the process parameters, including manipulated temperature, gas flow rate, liquid flow rate, aqueous ammonia concentration and CO2 inlet concentration. It is found that the Φ increases with the gas flow rate increasing, although the CO2 removal efficiency demonstrates the opposite trend. The experiment results show that the value of Φ is proportional to the bulk gas partial pressure (PCO2). Besides, the KGaV value could be determined by calculating the slope of the straight lines of the absorption rate against the bulk gas partial pressure at different ammonia concentrations. It is found that the KGaV value increases significantly when the aqueous ammonia concentration increases from 1.16 kmol/m3 to 4.54 kmol/m3.

► The overall absorption rate of the absorption of CO2 into aqueous ammonia solution in a packed column was studied.
► The suitable operating temperature range is from 35 °C to 40 °C.
► The overall absorption rate increases with the liquid flow rate, the gas flow rate, the ammonia concentration as well as the CO2 inlet concentration.
► The volumetric overall mass transfer coefficient is determined by the absorption rate.