MDEA-PG吸收剂联合中空纤维膜接触器脱除烟气中CO_2

Removal of CO_2 from flue gas by MDEA-PG absorbent combined with hollow fiber membrane contactor

在中空纤维膜接触器内研究了N-甲基二乙醇胺(MDEA)与甘氨酸钾(PG)所组成的混合吸收剂对烟气中CO_2的吸收性能,通过考察吸收剂浓度和配比对CO_2脱除率的影响,确定了混合吸收液最佳浓度为25%,最佳配比为2 mol/L MDEA+0.5 mol/L PG。在此基础上,探究了不同液相流速、吸收温度和压力下的CO_2吸收情况,结果表明,较高流速、温度和压力均有利于CO_2的吸收,流速为0.08 m/s时的平均脱除率相较0.02 m/s时提高了13.73%,温度从25℃上升到65℃时平均脱除率提高25.21%,0.45 MPa时的平均脱除率比0.15 MPa时提高67.31%,但过高的流速、温度和压力也同样会产生高能耗投入和设备腐蚀等问题,因此应该合理选择这3种操作参数的范围。

The absorption properties of CO_2 in flue gas were studied in the hollow fiber membrane contactor by the mixed absorbent composed of N-methyldiethanolamine( MDEA) and potassium glycinate( PG). The optimum concentration of mixed absorbing solution was 25% and the optimum ratio was2 mol/L MDEA + 0. 5 mol/L PG by studying the effect of concentration and ratio of absorbent on CO_2 removal rate. On the basis above,the absorption of CO_2 under different liquid flow rate,absorption temperature and pressure were investigated. The results show that higher flow velocity,temperature and pressure are all beneficial to the absorption of CO_2,when the flow velocity was 0. 08 m/s,the average removal rate was increased by 13. 73% compared with 0. 02 m/s,the average removal rate was increased by 25. 21%from 25 ℃ to 65 ℃,and the average removal rate at 0. 45 MPa was 67. 31% higher than that of0. 15 MPa. However,excessive flow velocity,temperature and pressure will also cause high energy input and equipment corrosion. Therefore,the range of these three parameters should be rationally chosen.