Experimental study on reaction heat of carbon dioxide absorption with organic amines

Key words:  ethanolamine  diethanolamine  reaction heat  absorption capacity  removal rate  desorption boundary

Abstract:

The self-developed CO₂ reaction heat testing system was applied to determine the CO₂ absorption capacity, absorption reaction heat under different temperatures, different concentrations and different pressures of ethanolamine (MEA) and diethanolamine (DEA).Then the removal rates of different systems were calculated and analyzed.The heat of desorption of MEA and DEA solution at different temperatures were measured, and the boundary of desorption reaction was analyzed as well.The results indicate that the reaction heat increases with the increase of temperature and pressure. However, the reaction rate improves slightly with the increase of pressure. The end boundary of desorption reaction can be determined through the conditions of the condensed water outlet, which are dispersed droplet and slug formed plug pipeline,respectivrly. In the latter situation, the equilibrium reactor pressure is about 1.5 kPa, and the gas flow rate is closed to zero. Under different temperatures, concentrations, and pressures, the reaction heat range of MEA solution absorption is 80-100 kJ/mol, and the reaction heat range of desorption is 100-140 kJ/mol.The reaction heat range of DEA solution absorption is 50-80 kJ/mol, and the reaction heat range of desorption is 70-100 kJ/mol.The change of absorption capacity of DEA solution with various absorption conditions is consistent with that of MEA. The absorption capacity of DEA solution is only about half of MEA, but the desorption rate is generally higher than 60%, meaning the desorption ability is stronger than MEA.