How to simulate distillation of binary homogeneous azeotropic systems using PROII
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Dear experts: How can PROII be used to simulate the distillation of a binary homogeneous azeotropic system consisting of cyclohexylamine and water? Which thermodynamic approach should be chosen for such systems? I would appreciate your advice on how to ensure reliable calculation results. Thank you in advance! The specific problem is as follows: it is a homogeneous solution containing cyclohexylamine, with a cyclohexylamine content of 15% (wt%, the same hereafter). The requirements are that the cyclohexylamine content at the top of the tower should be no less than 40%, while the cyclohexylamine content at the bottom of the tower should be no more than 2%. This system has a low boiling point; at atmospheric pressure, the boiling point is 96.4°C ； Azeotropic composition: 44.2% (cyclohexylamine). This post was last edited by GHJDSM on 2009-2-11 17:03]
The simulation of binary homogeneous azeotropic systems isn’t very different from ordinary simulations; the main difference is that the concentration of the product at the top of the tower cannot exceed the azeotrope temperature. One can use PRO2’s LVE tool to check the consistency of the vapor-liquid equilibrium data with the azeotrope temperatures, in order to select an appropriate thermodynamic model. Equations such as Wilson, NRTL, and UNIQFAC can be tried out.
In the absence of binary interaction parameters, I believe NRTL is the option that best reflects real-world conditions; select unifac for the Fill Option
Cyclohexylamine 【Relative molecular weight or atomic weight】99.18 【Density】Relative density 0.8647 (25/25°C) 【Melting point (°C)] -17.7 【Boiling point (°C)] 134.5 【Flash point (°C)] 32 Isn’t it a non-reforming component? I’m confused
The original post was published by yanwenzh1204 on 2009-2-20 at 15:29. Cyclohexylamine: [Relative molecular weight or atomic weight] 99.18; [Density] relative density of 0.8647 (25/25°C); [Melting point (°C)] -17.7; [Boiling point (°C)] 134.5; [Flash point (°C)] 32. Isn’t it a reconstituted component? I’m confused – the light and heavy components on either side of the azeotrope are not the same; you can understand this by looking at a T-X phase diagram with a low azeotrope.
Use PRO2’s LVE tool to examine their vapor-liquid equilibrium data and see if an azeotrope forms at a given pressure. Such simulated binary exchange parameters are quite heavy; if not available, UNIFAC or NRTL can be tried.
But at 40%, isn’t the azeotrope point not yet reached? Should that cyclohexylamine be at the top of the tower?