Analysis of the reasons for vacuum formation in the catalytic cracking fractionator top reflux pump?

Which distillation column is the poster referring to? Which device’s? Is it in the startup state or the operating state?

At the start or stop of operation, when the feed rate is low, the load on the tower is minimal, which may cause the top circulation pump to experience vacuum conditions. During normal production, the formation of salt deposits in the distillation tower can also lead to vacuum conditions in the top circulation pump

Bro, are you really drawing, or are you just coming up with a question to test the guys? I really don’t want to draw! I just finished dealing with the slurry, and now there’s this top circulation issue. It would be better to have the webpage saved! If there’s nothing to do, don’t smoke all the time – it’s annoying!

Control the temperature of the top recycle tower so that it is not too high; increase the stability difference between the extraction and recycling in the normal top recycle process, in order to reduce the circulation volume of the normal top recycle. If nothing else works, it’s necessary to add a little cold reflux. If time is available continuously after starting operation, should we consider the option of installing a liquid collection tank at the outlet? Suggestions: 1. Based on the results of the heat balance calculation, it is necessary to take into account that the heat taken from the upper part should be within the range of 25–30%; if this value is too low, the heat extraction point can be moved upward. 2. Analyze the composition of the overhead circulation to check whether any moisture is present An online dehydrator can be installed during maintenance ；

When the top circulation system draws in water, it is usually because the temperature of the gas drawn in through this system is too low, resulting in water being carried along with the gas. Salt accumulation can be addressed by washing; if the temperature at the extraction point is too low, the top temperature can be increased appropriately while ensuring that the dry point of the crude gas remains within acceptable limits, or the amount of water used for cooling can be reduced, or the amount of steam supplied to the reaction zone can be decreased (if possible). In this way, at the same top temperature, the vapor pressure of water decreases while the vapor pressure of oil and gas increases, making it easier for water to escape from the top of the tower. If water cannot easily escape from the top of the tower, it will remain there and accumulate over time. Once enough has accumulated, a qualitative change occurs, leading to the problems mentioned earlier. This helps to prevent water from being carried along with the gas in the top circulation system； Depending on the circumstances, it is also possible to increase the cold reflux at the tower top appropriately; this ensures that the dry point of the crude gas remains stable while allowing the top temperature to be increased slightly. Conversely, by increasing the vapor pressure of the oil and gas, the vapor pressure of water is reduced, which in turn helps to prevent water from being carried along in the overhead stream and avoids vacuum conditions in that stream. Of course, other factors such as those related to the oil collection tank itself also play a role.

The evacuation in the reflux pump at the top of the distillation tower is likely due to an obstruction in the pump inlet pipeline

I’ve encountered this situation several times; the main reason is that impurities clog the pump inlet. It can be fixed after cleaning it – don’t treat it as a serious problem.

Our company has experienced corrosion and perforation of the top circulation return oil tank, resulting in fluid leakage and unstable operation.

It might be cold return water. It could also be that the pressure at the top of the fractionation tower is insufficient, and the temperature in the middle section is too low