I have been trying to simulate a distillation column to separate butanol and water. The bottom product should be high purity butanol (>90%), I am able to match the composition, but I couldn't match the operating temp at the bottom (approx. 120 C, the temp indicator is at the column bottom with a meter of liquid above it). In my simulation the bottom product temp it gives is around 110 C.

All I can think of now is that the difference could be caused by the static head above the temperature indicator causing a higher bubble point at the bottom of the liquid sump. Can someone please confirm, or if you have experienced something similar, please share.

Thank you!

He will be missed.  Rest in peace, Steve.

1. Does this refer to the pipe outer-wall temperature or the actual bulk fluid temperature? Does maintaining the pipe wall at 35°C ensure that the fluid remains at this temperature?
2. As the gas flows, it may cool due to ambient heat losses and the Joule–Thomson effect as pressure decreases. Can heat tracing prevent water condensation under these conditions, considering that the dew point also changes with pressure? Would additional tracing duty or a temperature margin above the dew point be required?
3. Is tracing for temperature maintenance primarily intended to keep stagnant fluid warm when flow stops, or is it also designed to maintain fluid temperature during continuous flow?
4. What triggers the tracing to operate? Is it typically controlled by a sensor on the pipe wall beneath the insulation? How does this differ for self-regulating tracing?