Problems in distillation in atmospheric pressure columns: the phenomenon of simple processes becoming complex
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After increasing the lifting capacity of my device, I encountered a strange problem. The temperature of the thermocouple on the side line pipeline is higher than that of the side line oil collection tank. How should it be adjusted? (The temperature in the side-line oil collection tank is four or five degrees lower than that in the extraction pipeline.)
This is a common occurrence, where the temperature of the gas phase is higher than that of the liquid phase. It indicates that the evaporation rate has increased, but as long as it is kept within a certain range,
Oil and gas evaporation removes heat, resulting in a higher temperature in the gas phase than in the liquid phase; moreover, reactions occur at a faster rate in the gas phase. Taking advantage of this rapid change in gas phase temperature, it is possible to adjust the product quality in advance. If adjustments are made only after the reactions have taken place at the liquid phase temperature, the process will be much slower
The reason why the temperature of the thermocouple on the side line is higher than that of the side line oil collection tank is that the extraction port is small while the amount of liquid extracted is large; as a result, the saturated liquid at the extraction port vaporizes due to the siphon effect, causing its temperature to drop. In simple terms, it’s the funnel effect； As the liquid is drawn off with gas, at the point where the thermocouple is located on the side line (lower than the extraction point), the static pressure increases; the gas condenses and releases heat, causing the temperature to rise naturally. The poster can observe the position where the thermocouple is drawn out from the side line. Reduce the extraction volume to observe the temperature difference between the two thermocouples.