I wonder, in the distillation of water and methanol, since water turns into vapor and comes out together with methanol, how can we separate them using the difference in volatility during distillation...
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In the distillation of water and methanol, steam needs to be generated by heating at the bottom of the tower; in that case, both water and methanol turn into steam and come out together. How can separation be achieved by taking advantage of the difference in volatility between them? ?
Steam enters the shell side of the reboiler, not into the methanol.
First, keep the heating temperature above the boiling point of methanol and below the boiling point of water, to minimize the evaporation of water. Secondly, calculate the tower height properly to control the condensation of water while allowing methanol to be condensed in the condenser at the top of the tower. If the separation effect is not up to standard, reflux can be used
Methanol is evaporated through heat exchange in a reboiler and then distilled
The last edit to this post was made by Qingchengjun on 2017-9-9 at 15:17. Here’s a set of data to help you understand the situation: Assume that in a methanol-water system in the tower bottom, when heating takes place, 25% of the water evaporates, while 99.9% of the methanol evaporates. During the subsequent rise, 24.99% of the water returns to the tower bottom through heat and mass transfer, whereas 30% of the methanol does not enter the condenser due to liquefaction. The tower top can collect 70% of the methanol in its first ascent, with a purity of 99.9%
What I want to say is. Your tower is a distillation tower, not a stripping tower. In other words, the steam entering the tower bottom is heated through a heat exchanger or a heating coil. Secondly, the composition at the top of the tower depends on many factors, including the composition at the bottom of the tower, the efficiency of the tray (whether it is a packed tower or a plate tower, the packing height, the number of trays), the reflux ratio, and so on. Find a good book on distillation operations and study it*; it is the foundation of chemical process technology.