Low pressure difference in the distillation tower
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There are currently two distillation columns of the same specifications; in one of them, part of the packing has been removed, with a pressure of -94 kPa at the top and -76 kPa at the bottom, while in the other column the pressure is -95 kPa at the top and -91 kPa at the bottom. The temperatures at the top and bottom of both columns are similar. What could be the reason for this?
Take a look at the chapter on pressure drop in chemical engineering principles, understand what factors affect pressure drop, and then analyze it in light of practical situations. After analysis, targeted information and answers to questions can be provided
No one other than you can determine this specific reason
1. Please calibrate the pressure gauge at the bottom of the tower. 2. If the instrument is functioning properly, consider whether the removal of the packing has caused local flooding
With the same number of remaining trays, the temperature on a tray in a distillation column is determined by the temperature of the gas and liquid above it, and the level of this gas-liquid temperature is in turn determined by the pressure as well as their oxygen (or nitrogen) concentrations. Plate resistance refers to the pressure drop that occurs as rising vapor passes through the sieve holes in the plate and the liquid layer on the plate. As the vapor passes through the sieve holes of the tray, changes in the cross-sectional area of the flow channel cause variations in the flow, thereby creating resistance to that flow. This resistance exists whether there is liquid on the tray or not; it is known as dry tray resistance. It is related to factors such as the speed at which vapor passes through the sieve pores, the porosity of the tray, and the roughness of the pores. Rising vapor must also overcome the resistance caused by the surface tension of the liquid in order to enter and escape from the liquid layer. This resistance is known as surface tension resistance; it is proportional to the surface tension of the liquid and inversely proportional to the diameter of the pores. The rising vapor must also overcome the resistance caused by the static pressure of the liquid layer on the tray in order to rise; this resistance is known as the liquid column static pressure, and it is related to the thickness of the liquid layer and the density of the liquid. It can be seen that the pressure at the top of the tower is related to factors such as tower resistance, the number of trays, and the installation of the trays