Why is the heat exchange efficiency worse as the liquid level in the distillation tower increases? Even with all the steam valves opened, the flow rate is still insufficient.
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It’s strange that a higher liquid level should result in a worse heating effect; the distillation tower is of the type where heat exchange takes place at the bottom of the tower, without having a separate heat exchanger.
A thermosyphon reboiler? A high liquid level affects the heat exchange area; certainly, the higher the liquid level, the worse the heat exchange efficiency.
If siphon heat exchange is used, poor heat transfer will definitely occur if the liquid level exceeds the top of the reboiler; it is best to maintain the liquid level at two-thirds of the reboiler’s capacity
The heat exchanger is at the bottom of the tower; it is not a siphon heat exchanger. In other words, the heat exchanger and the distillation tower are integrated together.
Reply to 4# peach1120: A high liquid level indicates an abundance of material at the bottom of the tower; with more material present, the heating effect is reduced. It’s the same principle: with the same amount of heat used to boil water, it takes a different amount of time to boil a pot compared to a large kettle.
The poster is referring to an internal reboiler, which is generally used in situations where the material contains many impurities. Insufficient flow means low backflow, right? Check if your load is much higher than the designed value.
There is an imbalance in material inflow and outflow, as well as a imbalance between cold and hot fluids; try increasing the amount of residual fluid or reducing the amount of cold fluid.
1. Check the temperature of the tower bottom; if it is higher than the normal value or higher than the design value, it may be due to an excessive accumulation of heavy components in the material at the tower bottom. A large amount of the bottom liquid in the tower should be discharged, while maintaining a certain liquid level. 2. If the reactor temperature is normal, it may be due to a change in the material composition, with an excess of higher molecular weight components. 3. Is the top cooling reflux too high? If the top temperature is lower than the normal value, it should be reduced to a reasonable reflux ratio.
I don’t understand, haha. I’ll hold your spot; hope this can help you
Is the heat exchanger clogged? Is there any solid powder in the feed? With the heat exchange area increasing, the heat exchange efficiency must decrease!
Reply to 1# peach1120: It’s not that the heat exchange efficiency is worse; rather, the liquid level in the distillation tower is high and the amount of material is large, so the heat exchange capacity is insufficient.