Urgent! A problem in azeotropic distillation that needs to be addressed urgently
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An old issue that was discussed on the forum before; now it seems there’s a problem again. I earnestly ask those who are more knowledgeable to share their insights! It’s like this: in the simulated distillation process for converting DCH into ECH, DCH reacts with NaOH inside the distillation tower to produce EDC and water. The products are obtained from the top of the tower. The problem is that ECH and water are azeotropic, with an azeotrope temperature of 90.2 degrees and a water content of 30% (by weight). Yet, in my simulations, the temperature is always around 93 degrees, with a water content of over 40% – which makes no sense. In actual distillation, the temperature should reach the azeotrope temperature and then stop rising, and the composition should remain unchanged. I would like to ask those who know more about this what exactly is going wrong? My hair is almost turning white~~~~~ The simulated basic conditions are as follows: the module selected is a tower without a condenser in the radfrac type; there are 20 trays in total, with 5 feed streams. The reaction zone consists of 5–10 trays. The gas phase at the top of the tower is condensed, and after phase separation in a decanter, the aqueous phase is returned to the top of the tower as reflux, while the oily ECH phase proceeds to the next processing step. What exactly is the problem? ? ?
Considering I’m still working hard in the early hours, the experts really should feel free to share their advice! !
The calculated azeotrope composition and boiling point depend greatly on the property calculation method you use. Also, I wonder if you have taken pressure into consideration?
The issue is that the system I am simulating contains NaOH, so I can only use the electrolyte property method, specifically ELECNRTL. If I change to another property method, the calculations cannot be carried out. The operation takes place at atmospheric pressure. So what exactly is the problem?
I learned this in class, hehe. I’m a beginner too; I’ve been studying this recently.