常压下乙醇-空气-水汽液平衡常数的测定

Measurement of equilibrium constants of ethanol-air-water system at atmospheric pressure

采用定制的汽液平衡釜,测定了常压(101.3 kPa)下乙醇-空气-水多元体系平衡常数与液相乙醇物质的量分数和温度之间的关系,为水吸收空气中的乙醇过程提供数据参考。汽、液两相乙醇物质的量分数分别用气相色谱的外标法和归一化法测定,实验数据通过了Van Ness点检验法的热力学一致性检验。用Wilson、NRTL和UNIFAC热力学模型对该体系的平衡实验数据进行了关联,其中Wilson模型与实验数据最为吻合,其汽相平衡乙醇物质的量分数和平衡常数最大平均偏差分别为0.002026和0.026800,并通过拟合得到了平衡常数经验公式。结果表明,实验测定的平衡常数较为准确。

Using the customized vapor-liquid equilibrium kettle,the relationship between the equilibrium constant of ethanol-airwater multicomponent system at atmospheric pressure(101.3 kPa)and the mole fraction of liquid ethanol and temperature was measured,which provided a data reference for the process of water absorbing ethanol in air.The mole fraction of ethanol in vapor and liquid phases were measured by external standard method and normalization method of gas chromatography respectively.The experimental data passed the thermodynamic consistency test of Van Ness point test.The equilibrium experimental data of the system was correlated by Wilson,NRTL and UNIFAC thermodynamic models.The Wilson model is in the best agreement with the experimental data,and the maximum average deviations of its gas-phase equilibrium ethanol mole fraction and equilibrium constant are 0.002026 and 0.026800 respectively.The empirical formula of equilibrium constant was obtained by fitting.The results show that the equilibrium constant measured by experiment is accurate.