沼气提纯过程中醇胺溶液吸收CO_2传质性能

Mass transfer in CO_2 absorption by alkanolamine aqueous solution for biogas purification

醇胺溶液吸收CO2是沼气提纯领域重要的研究课题。在实验填料吸收塔中,以乙醇胺（MEA）、二乙醇胺（DEA）为吸收剂,研究了吸收剂浓度、进气流量、CO2浓度、进液温度对吸收过程转化率η、吸收速率N以及气相总体积传质系数KGae的影响。结果表明,吸收剂浓度增加可有效提高η、N及KGae;进气流率增加,η逐渐降低,N先增加后降低,KGae先增加后降低最终趋于稳定;随着CO2浓度增加,η和KGae不断降低,N逐渐增加;随着进液温度升高,η和KGae均先升高后降低;MEA、DEA的最佳进液温度在40～60℃之间,并随CO2负载量增大而逐渐降低。研究结果对于醇胺溶液吸收法沼气提纯技术的研究开发和实际应用有参考作用。

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℃,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.