How to calculate the reboiler of the tower
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I am calculating a tower and matching reboiler, and the simulation has passed. The main question now is how to determine the relative position of the tower and reboiler? 1. Knowing the minimum liquid level of the tower kettle requires overcoming the pipeline resistance, the height of the reboiler liquid level and the loss pressure drop of the reboiler equipment. 2. The reboiler is a thermosiphon type. The problem that requires help is: (1) The vaporization rate of a thermosiphon reboiler is generally 30%. Is the circulation volume of the reboiler = liquid volume/vaporization rate on the simulation software? (2) How to calculate the equipment pressure drop of a thermosyphon reboiler? Can it be calculated on PROII?
Can a dummy stream be added to the circulation volume of the reboiler like the reflux volume? For reference only, learn * middle.
When the virtual flow is pulled out, the liquid phase of the last plate enters the reboiler. The reboiler is selected according to the flow rate. The gasification rate of the thermosiphon reboiler is generally designed around 20%-30%. I don’t know if it’s correct or not, so I’d like to ask an expert for guidance.
Regarding this problem, you can simulate it by splitting the equipment, that is, passing the bottom outlet stream and then adding a heater, separator, and pump circulation. However, the pressure drop can only be calculated through specialized equipment software.
A virtual stream should be pulled directly into the tower kettle, and a heat exchanger should be added. The definition of the heat exchanger gives the heat load of the tower kettle, and the calculation
The last plate (non-reboiler) pulls out a virtual stream (liquid phase). This flow rate L1 is known, the tower reactor output L2 is known, the reboiler inlet flow is L3, then the reboiler outlet gas phase is 0.3* L3, the outlet liquid phase is 0.7 * L3。 And L1+0.7 * L3=L2+L3 This formula can calculate the value of the liquid phase amount L3 at the reboiler inlet. Reconstruct another stream. The composition of this stream is the same (approximately) as L1, and the flow rate is L3. This stream then enters a heat exchanger, and the outlet liquid phase fraction is 0.7. After the reboiler is built, you can compare the reboiler load with the tower's own reboiler load. There is a difference but not a big one. My personal approach, please check if it is correct.
I understand that virtual logistics cannot be used to build a thermosiphon reboiler. The heat load is only related to the gas phase mass flow rate, but the gas phase flow rate and liquid phase flow rate of the distillation tower are not equal to the vaporization amount of the reboiler. Assume that the simulation result is that the liquid phase flow rate of the penultimate plate is 6000, the gas phase flow rate of the penultimate plate is 1000, the production is 5000, and the gasification rate is 20%, the circulation volume should actually be 5000, not the liquid phase flow rate of 6000.