N-甲基二乙醇胺/哌嗪溶液和氨水吸收二氧化碳的实验研究

Absorption of carbon dioxide by methyldiethanolamine/piperazine and aqueous ammonia

MDEA/PZ溶液被认为是目前燃煤电厂煤燃烧后脱碳过程中一种很有应用前景的化学吸收剂.反应速率和气液平衡是研究CO2吸收剂的重要参数.因此,本文在一个加压湿壁塔实验台上,针对45%MDEA/5%PZ(质量分数)溶液进行实验研究,得到了溶液在20～60℃时的反应速率和在20～120℃之间低CO2负载量(<0.2mol·mol-1)条件下的CO2平衡分压,并拟合出了平衡分压的半经验关联式.鉴于氨水是目前另一种被广泛关注的CO2吸收剂,本文在相同的实验装置上,进行了5%氨水的吸收速率实验,并与MDEA/PZ的实验结果进行了对比.结果表明,两者在20℃和40℃之间的吸收速率接近,20℃时氨水的吸收速率略高,但MDEA/PZ溶液在40℃时的吸收速率高于氨水.基于研究结果,本文推荐45%MDEA/5%PZ溶液的吸收温度窗口应为40～60℃,氨水应为20～40℃.

MDEA/PZ solution is considered to be an effective absorbent to absorb CO2 from coal-fired power plant.Both absorption rate and vapor liquid equilibrium are important parameters for a CO2 absorbent.A pressurized wetted wall column was used to study the CO2 absorption rate in 45% MDEA/5% PZ solution at 20-60 ℃.The solubility of CO2 under low CO2 loading（〈0.2 mol · mol^-1） from 20 ℃ to 120 ℃ were also measured in WWC,based on which semi-empirical correlations of CO2 partial pressure with CO2 loading and temperature were fitted.The absorption rate of CO2 in 5% NH3（aq） was also measured to compare with MDEA/PZ.The comparison result indicated that CO2 absorption rates of 45% MDEA/5% PZ and NH3（aq） between 20 ℃ and 40 ℃ were closed to each other.5% NH3（aq） was a little higher at 20 ℃ and lower than that of MDEA/PZ solution when the temperature was up to 40 ℃.Based on the experiment results,the temperature windows of MDEA/PZ and NH3（aq） used as absorbents of CO2 were suggested as 40-60 ℃ and 20-40 ℃,respectively.