Operation of vacuum towers
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After the tower is evacuated, the vacuum level decreases; why then do the temperatures at the bottom and top of the tower rise, and what is the reason for this increase?
As the vacuum level decreases, the pressure inside the tower increases; as a result, the boiling point of the material rises as well. The temperature of the steam generated at the bottom of the tower increases, which in turn leads to an increase in the temperature inside the tower
The main reason is the operator's actions, which cause a sudden decrease in the product taken from the top of the tower, resulting in an empty level in the reflux tank. The reflux volume decreases; the rest is as explained above.
The vacuum level inside the tower decreased, preventing the turbine exhaust from being carried away properly; as a result, heat remained inside the tower, causing its temperature to rise.
You can calculate it by yourself using the ideal gas law
Once a vacuum is established, more light components will inevitably enter the top of the tower, which increases the concentration of heavier components at the bottom of the tower. Temperature reflects the composition of the mixture, so it rises as a result
As the vacuum level in the tower decreases, the boiling point of the material rises; to achieve the original separation efficiency, the temperature at the bottom of the tower must be increased
As the vacuum level decreases, less light component evaporates in the tower, resulting in less heat being carried away
The boiling point of the material suddenly rises; the vapor that forms upon boiling liquefies and releases heat, causing the temperature to increase.
A decrease in the vacuum level of the tower indicates an increase in tower pressure. As the temperature of the tower rises, the boiling point of the material remains constant at a given pressure
The vacuum level dropped, and the tower pressure increased. This change in tower pressure affects the volatility of the materials; more light components end up in the liquid. According to the law of conservation of energy, if heat does not cause the light components to evaporate, it will raise the temperature of the liquid.