Could some expert explain to me the gas-liquid equilibrium in methanol distillation?
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Hello everyone, I’ve been studying methanol distillation recently, and the topic of discussion was the three major equilibria. Heat balance, mass balance, and gas-liquid equilibrium. The first two are easy to understand, but gas-liquid equilibrium seems a bit abstract, for example ； In gas-liquid equilibrium, which components are in equilibrium exactly, the heavy components? Light components? It’s still methanol. Is balance based on that? As I understand it, the light components in the upper part of a distillation column cannot be the same as those at the bottom of the column; by the same logic, the heavy components should also be different. So is this meaning that these two groups are ruled out? The materials also state that in a distillation column, gas-liquid equilibrium and heat equilibrium are maintained on each tray. Heat equilibrium is easy to understand – it occurs as a result of heat exchange between the gas and the liquid. The question is, what is the basis on which the material balance in it is achieved? Please, an expert, explain it in more detail. :)
The gas-liquid equilibrium is determined by the relative volatility of the material at that temperature on that tray
In simple terms, it means that in a given component, the number of molecules that change from the gas phase to the liquid phase is roughly equal to the number of molecules that change from the liquid phase to the gas phase. If there is a discrepancy, it indicates a non-steady state, that is, a state of imbalance, which will gradually change until equilibrium (steady state) is reached.