Mass transfer in CO2 absorption by alkanolamine aqueous solution for biogas purification

CO2 absorption by alkanolamine aqueous solution is an important method for biogas purification. A series of experimental tests were conducted in a packed tower using aqueous solution of MEA and DEA, in which the percent conversion η, absorption rate N and volumetric overall mass transfer coefficient in gas phase KGae were analyzed at various absorbent concentrations, gas flow rates, CO2 concentrations and absorption temperatures. The results show that the increment of absorbent concentration can improve η, N and KGae effectively. With the increment of gas flow rate, the percent conversion η decreases obviously, while the absorption rate N increases within a certain range and then decreases, the change of KGae is similar to that of absorption rate N, but the value of KGae will maintain a relatively stable value when the gas flow rate is high enough. The percent conversion η and decrease as CO2 concentration increases, while the absorption rate N increases. The effect of absorption temperature on η and KGae are approximately parabolic. The optimum absorption temperature of MEA and DEA is about 40-60°C, and it decreases with the increment of CO2 loading. The experimental results of this study can provide some guidance for the further study and practical application of biogas purification technology by alkanolamine aqueous solution. © All Rights Reserved.