Analysis of the causes of pressure fluctuations in distillation columns
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There is a distillation tower at the top of our company’s reactor, which is used primarily to separate CPL from water. During normal operation, due to improper adjustments in the reactor feed and the amount of pure water used as reflux, the pressure in the distillation tower rises rapidly from 0.033 bar to 0.045 bar every seven or eight hours (the exact interval is not fixed). The pressure control valve also increases from 65% to 100% under these conditions. The distillation tower has eight layers of trays at the upper part and a packing layer at the lower part. We would appreciate it if experts could help analyze the reasons behind this phenomenon and suggest solutions. Our engineers believe that there may be a blockage in the packing layer; however, since the outlet pressure p4001102 changes in sync with the pressure variations, I think that if there were indeed a blockage, the outlet pressure should be lower
It’s as if the backflow is suddenly interrupted. It causes overpressure in the tower.
You engineers are right; the blockage caused flooding
You engineers are right; the blockage caused flooding
You engineers are right; the blockage caused flooding
Are there any pictures? No matter how well it’s described, nothing beats visuals
Have you considered CPL crystal clogging?
Pressure is also an important factor affecting distillation operations. The operating pressure of a distillation tower is determined by the designer after comprehensive consideration of process requirements, economic benefits, and other factors, and it cannot be changed arbitrarily during operation. The main effects of pressure fluctuations in the tower on distillation operations are as follows. (1) Fluctuations in operating pressure will cause changes in the gas-liquid equilibrium relationship on each tray. As pressure increases, the amount of poorly volatile components in the gas phase decreases, while the concentration of volatile components increases; the concentration of volatile components in the liquid phase also increases ； At the same time, as pressure increases, vaporization becomes more difficult; the amount of liquid phase increases while that of the gas phase decreases, resulting in changes in the gas and liquid phase loads within the tower. The overall result is an increase in the concentration of volatile components in the tower top distillate, but a decrease in yield ； The concentration of volatile components in the reactor broth increases, and the volume of the reactor broth also increases. In severe cases, it can disrupt the material balance within the tower, affecting the proper operation of distillation. (2) As the operating pressure increases, the relative volatility between components decreases, the concentration-enhancing capacity of the tray decreases, and the separation efficiency declines. However, as the pressure increases, the density of the components rises, and the processing capacity of the tower increases. (3) Fluctuations in tower pressure will also cause changes in the correlation between temperature and composition. It can be seen that changes in the operating pressure of the tower will affect the overall operating conditions of the tower. Therefore, during production operation, the operating pressure should be kept as constant as possible.
A sudden change in pressure indicates a sudden change in the load inside the tower. It is generally a phenomenon of mist entrainment causing tower flooding.
The poster’s description isn’t very clear to me. Does the reactor product go into the distillation tower? Are there PID or PFD values available for analysis?