30kPa下乙二胺–水体系汽液相平衡数据的测定及关联

Measurement and Correlation of Vapor-liquid Equilibrium of Ethylenediamine and Water System at 30 kPa

对于乙二胺和水形成的最高共沸物体系,用常规的精馏方法难以进行有效分离。变压精馏是一种利用共沸点随压力变化而显著改变的特点实现共沸物分离的特殊精馏方法,为获得变压精馏计算所需的热力学模型和参数,采用Rose型汽液平衡釜测定乙二胺-水二元体系在30 kPa下的汽液相平衡实验数据,采用Herington面积积分法对实验数据进行热力学一致性检验;在此基础上,分别采用UNIQUAC和NRTL活度系数模型对汽液相实验数据进行关联,回归得到二元系统的相互作用参数和2种模型下实验值与预测值的偏差。结果表明:NRTL和UNIQUAC活度系数模型分别对应的平均绝对偏差为0.028 05,0.030 78,2种模型均能较好地关联乙二胺-水体系相平衡数据;相较而言,NRTL模型与低压下的乙二胺-水汽液相平衡数据符合度更高,更适合模拟低压下乙二胺-水体系的分离工艺。

For the highest azeotrope system formed by ethylenediamine and water,it is difficult to effectively separate by conventional distillation methods.Pressure-swing distillation is a special distillation method that completes azeotrope separation based on the characteristic that the azeotrope point changes obviously with pressure.In order to obtain the thermodynamic model and parameters required for pressure-swing distillation calculation,the vapor-liquid equilibrium data of ethylenediamine-water binary system at 30 kPa were measured by Rose vapor-liquid equilibrium kettle,and the thermodynamic consistency of the experimental data was tested by Herington area integration method.On this basis,UNIQUAC and NRTL activity coefficient models were used to correlate the experimental data of vapor-liquid phase,and the interaction parameters of binary system and the deviation between experimental values and predicted values under the two models were obtained by regression.The results show that the average absolute deviations of NRTL and UNIQUAC activity coefficient models are 0.02805 and 0.03078,respectively,and both models can well correlate the phase equilibrium data of ethylenediamine-water system.In contrast,the NRTL model is more consistent with the data of ethylenediamine-water vapor liquid equilibrium at low pressure,and is more suitable for simulating the separation process of ethylenediamine-water system at low pressure.