Effects of operating parameters on the absorption of carbon dioxide in ammonia solutions

This study aims at the effects of operating parameters on the absorption of carbon dioxide from flue gases by ammonia scrubbing to reduce the greenhouse effect. Studies of process control were performed under inlet carbon dioxide concentrations of 8-16% (v/v), gas flow rates of 2-10 lpm, ammonia solution concentrations of 7-35% (w/w), and reaction temperatures of 25-35. The results indicated that NH₃ solution concentration and the reaction temperature have significant effects on the CO₂ removal efficiency and the absorption capacity, whereas the inlet CO₂ concentration has only slight effects on its removal efficiency and absorption capacity. Similar tests were also done for CO₂ removal by monoethanolamine (MEA) solution. Under the same operating conditions, the removal efficiencies of carbon dioxide by ammonia scrubbing (approximately 98%) are higher than those by MEA scrubbing (approximately 80%). The absorption capacities of ammonia scrubbing (0.70 to 1.40 kg-CO₂/kg-NH₃) are also better than those of MEA scrubbing (0.20 to 0.40 kg-CO₂/kg-MEA). In view of these results, it can be concluded that ammonia scrubbing is an effective treatment process for the removal of carbon dioxide from flue gases.