有机醇胺-水体系混合热和气液平衡的测定与计算

Measurement and calculation of excess molar enthalpy and vapor-liquid equilibrium for alkanolamine-water

作为酸性气体吸收剂,醇胺水溶液在气体混合物分离过程中被广泛应用。选择吸收速率高、吸收能力强的新型醇胺吸收剂,对于二氧化碳捕获技术发展尤为重要。醇胺水溶液对二氧化碳的吸收性能与其热力学性质直接相关,因此对于新型吸收剂的选择,必须首先确定体系的气液平衡和溶解热等重要热力学性质。文章利用C-80微量热仪在全浓度范围内,测定了303.15,323.15 K下2-乙氨基乙醇和水的混合热,并用沸点仪测量了30—100 kPa条件下该体系的气液平衡数据,用非随机双流体NRTL方程关联计算了混合热和气液平衡数据,并给出了方程模型参数。气液平衡和混合热数据的拟合结果和实验值能很好地吻合,表明该模型能用于醇胺水溶液吸收二氧化碳过程,并有助于吸收剂性能评价、新型吸收剂的选择以及吸收流程的模拟优化。

As the absorbents of acid gases, aqueous alkanolamines are extensively applied in the separation process of gas mixtures. A new alkanolamine absorbent with high absorption rate and strong absorptive capacity is particularly important for the development of the carbon dioxide capture technology. Since the thermodynamic properties of alkanolamines correlate directly to their absorption performance, a preliminary understanding of these properties is necessary. The molar excess enthalpies for （2-ethylamino） ethanol （EAE） in water were measured with C-80 calorimeter at 303.15, 323.15 K and over the entire range of mole fractions. The isobaric vapor liquid equilibrium （VLE） data were also measured for the EAE-water binary system ranged from 30 kPa to 100 kPa by using equilibrium vessel. The nonrandom two-liquid （NRTL） model was used and its parameters were simultaneously fitted using HE and VLE data. The calculation results are in good agreement with the experimental data, showing that the present thermodynamic model can be reliably used for the calculation of absorption processes. The model is also helpful for the choice of new absorbents, evaluation of absorption capability, and optimization of absorption processes.