氨法脱碳系统再生能耗的研究

氨水溶液能够实现较高的CO2脱除率,具备较大的吸收能力,同时能够脱除烟气中SOx和NOx等酸性气体,近年来被认为是具有发展潜力的CO2吸收剂。普遍认为氨法再生过程的反应热能耗可降至26.88kJ.(molCO2)-1,远低于MEA能耗85kJ.(molCO2)-1。文中对比大量文献中的再生能耗数据,分析了其数据可靠性,理论计算和量热计实验测量低温下(35℃)氨水吸收CO2吸收热为60～70kJ.(molCO2)-1,并且随着CO2负载量增大无明显变化;高温下(80℃)初始吸收热热值约为60kJ.(molCO2)-1,随着CO2负载量增大而增大至120kJ.(molCO2)-1,然后再次减小至80kJ.(molCO2)-1。碳酸铵溶液吸收CO2过程吸收热测量实验也证实了氨水吸收CO2过程无法实现26.88kJ.(molCO2)-1低热值。和其他醇胺溶液吸收热热值相比,氨水溶液在降低能耗方面具有一定优势,但是优势不明显。

Research on heat requirement of aqua ammonia regeneration for CO2 capture

Aqua ammonia is thought to be a feasible new absorbent for CO₂ capture in recent years because of its high CO₂ removal efficiency, high loading capacity and the possibility of removing NO_x and SO_x simultaneously.The heat of reaction for aqua ammonia regeneration was considered as low as 26.88 kJ·（mol CO₂）^-1 before, which was much lower than 85 kJ·（mol CO₂）^-1 for MEA regeneration.Data from literature were collected and compared, and their reliability was analyzed in this work.It was found that both our theoretical estimation and experimental data disagreed with those from earlier economic analyses for aqua ammonia capture system.The experimental data in this paper also confirmed that the heat of absorption was about 60—70 kJ·（mol CO₂）^-1 and was seemingly independent of CO₂ loading at a low temperature (35℃).The heat of absorption at a high temperature (80℃) was about 60 kJ·（mol CO₂）^-1 at the beginning, rose to a maximum of around 120 kJ·（mol CO₂）^-1 with increasing loading, and then decreased to 80 kJ·（mol CO₂）^-1 after a certain high loading value was reached.It was impossible to get heat of absorption as low as 26.88 kJ·（mol CO₂）^-1 according to the experimental data of CO₂ in ammonium carbonate solutions.Therefore，aqua ammonia had advantage in energy saving, however the advantage of aqua ammonia over other amine solutions was not as obvious as expected.