N-甲基二乙醇胺水溶液脱除SO_2热力学分析

Thermodynamic analysis of SO_2 removal by N-methyldiethanolamine solution

通过N-甲基二乙醇胺(MDEA)吸收SO2实验,以及应用热力学方法根据MDEA吸收CO2的热力学数据估算MDEA吸收SO2的焓变,采用基团加和法计算反应熵变,进而得到MDEA吸收SO2的吉布斯自用能变和反应平衡常数,并与石灰石-石膏湿法吸收SO2的吉布斯自用能变与反应平衡常数进行比较,结果表明:利用MDEA脱除SO2是可行的;低温条件下MDEA吸收SO2比石灰石-石膏湿法的反应自发程度更大,更容易进行,且能耗较低;采用MDEA脱硫可节约吸收剂使用量,且副产物价值更高,具有良好的发展前景。

The feasibility of SO2 removal by N-methyldiethanolamine（MDEA）was analyzed by thermodynamics method.The enthalpy change of MDEA during reaction with SO2 can be estimated according to the thermodynamic data of CO2 removal by MDEA.The standard entropy change of the reaction can be estimated by group contribution method.Then the reaction Gibbs function change and equilibrium constant can be obtained.Compared with the thermodynamic parameters of calcium carbonate absorbing SO2,it is verified theoretically that the MDEA has better capability in removing SO2 than the calcium carbonate.The thermodynamic analysis and experiments of MDEA desorbing SO2 show that,applying the MDEA to remove SO2 can save absorbent usage and the byproduct value is higher,which is a desulphurization process with great potentials.