How is the temperature of the side-line extraction controlled, and what is the principle behind it?
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How is the temperature of the side-line extraction controlled, and what is the principle behind it? Thank you
The side stream withdrawal temperature is generally controlled by the reflux to the tower below the side stream. The amount of material returning to the tower is large; there is an adequate amount of liquid phase in the gas-liquid mass and heat transfer process, resulting in excellent mass and heat transfer efficiency. More heat from the gas phase is transferred to the liquid phase, which leads to a lower temperature for side-stream extraction. The temperature returning to the tower below the side stream is low; during gas-liquid mass and heat transfer, the temperature difference between the gas and liquid phases is large, resulting in efficient heat transfer. As a result, more heat is transferred from the gas phase to the liquid phase, and the temperature at which the material is extracted from the side stream is low.
It is also possible to control the amount of side stream drawn off. The draw rate decreases, the liquid phase reflux on the lower trays increases, more heat is absorbed, and thus the side-stream draw temperature naturally drops. Controlling the backflow to the top section is also an option, but it will cause a general drop in temperature inside the tower.
The last edit to this post was made by wxj98710 on 2009-9-7 at 09:04. As for the temperature and flow rate of the material taken out via the side stream, the following factors should be considered: operations should be carried out on the basis of material balance, with the feed volume, return flow volume, side stream output volume, and bottom flow volume all being in a state of dynamic equilibrium to ensure stable operation. In other words, the extraction temperature is not controlled directly; it is determined under the overall material balance conditions, based on the corresponding number of trays.