The bottom temperature of the pressure tower cannot be increased

It is likely to be an air blockage; the temperatures at the top and bottom of the tower fail to rise. To solve this problem: reduce the steam supply and feed material again

It seems that the temperature in the atmospheric pressure column should also stop rising. I’m not sure what the pressure in the pressurized column is like; if it’s not low either, then the pressure equalizing valve on the reflux tank of the pressurized column can be opened to release some pressure. Of course, there is also low steam pressure or low temperature; furthermore, the prognosis is poor, and it’s not easy to increase the temperature in the pressurized tower.

1. The tower bottom is empty. 2. The tower bottom is full; it’s overflowing. 3. The reboiler is leaking

First, we need to talk about what measures you took yet still couldn’t bring it up

I can’t increase the temperature~ Has there been any change in your steam flow? Check whether the steam condensate can be drained. Is it possible that the tower has already been flooded? Also, what is the water content in your crude methanol?

The overall environmental pressure and temperature should be analyzed and addressed layer by layer!

Check whether the steam volume of the reboiler has changed, as well as the liquid level in the tower bottom.

There are several scenarios: 1. The liquid level in the pressurized tower is empty; 2. The load on the atmospheric pressure tower is too high, causing the reflux liquid to be undercooled. Associated phenomena: low pressure in the pressurized tower and excessively low temperature at the bottom of the atmospheric pressure tower

There are several scenarios: 1. The liquid level in the pressurized tower is empty; 2. The load on the atmospheric pressure tower is too high, causing the reflux liquid to be undercooled. Associated phenomena: low pressure in the pressurized tower and excessively low temperature at the bottom of the atmospheric pressure tower

Handle each case individually, depending on the cause. There are many possible reasons: insufficient steam pressure or temperature, excessive tower capacity, high reflux volume, and low temperature

First, check whether the steam pressure and flow rate of the reboiler are too low; then check if there is any blockage in the condensate traps and pipelines, or if the amount of condensate drained is insufficient. The feed density in the pressurized tower should not exceed 0.88 g/cm3; check whether there is severe internal leakage in the reboiler of the atmospheric tower, and whether the flow rate through the connection pipe from the reflux tank of the pressurized tower to the cooler of the atmospheric tower is too high.

I think we should rule each possibility out one by one: 1. Equipment issues: The filler might be clogged; it’s necessary to check the pressure difference and product quality to determine this. 2. Instrument problems: The likelihood is low, but it’s possible; this can be ruled out by comparing with other temperatures. 3. Steam issues: This is a aspect that might be overlooked, such as low pressure. 4. Process issues: (1) The liquid level in the pressurized tower is low, the load on the atmospheric tower is too high, and the reflux liquid is undercooled; accompanying symptoms include low pressure in the pressurized tower and excessively low temperature at the bottom of the atmospheric tower. (2) The reflux ratios in the pressurized and differential pressure towers are not appropriate. I think that by adjusting the corresponding temperatures and pressures, the product quality can be improved; 4 kilograms should be sufficient

I agree with what was said above; I managed to do it at a low load of 3.8 kilograms

The bottom temperature and bottom pressure of the pressurized tower are related to each other. Under normal conditions, if the bottom temperature does not rise, then the bottom pressure will not rise either, which indicates that the top pressure of the pressurized tower will also not increase. If issues such as problems with steam from the bottom reboiler, methanol displacement inside the tower during startup, or problems with the valves in the pipelines connecting the pressurized tower to the atmospheric pressure tower have been ruled out, then the most likely problem is a mismatch in the capacity of the reboilers in the pressurized tower and the atmospheric pressure tower. This mismatch could be due to too low a steam pressure in the reboiler of the pressurized tower, or it could be that the reboiler in the atmospheric pressure tower has too high a capacity. It can be said that whether the pressure in the pressurized tower can increase depends entirely on the rate at which heat is added to the reboiler in the pressurized tower and the rate at which heat is removed from the reboiler in the atmospheric pressure tower. During the startup of the pressurized tower, the pressure is low, the temperature difference across the reboiler is large, so heat is added quickly. In the atmospheric pressure tower, the temperature difference is small, so heat is removed slowly. Thus, as steam is gradually added to the reboiler in the pressurized tower, its pressure increases gradually. As the pressure in the pressurized tower rises, the bottom temperature also increases, and the temperature difference across the reboiler decreases, resulting in a slower rate of heat addition. At the same time, the temperature difference across the reboiler in the atmospheric pressure tower increases, leading to a faster rate of heat removal. If the design is proper, the reboilers in the pressurized tower and the atmospheric pressure tower should reach equilibrium at full load, meaning that the pressurized tower reaches its designed pressure and the bottom of the tower reaches its designed temperature. Therefore, the reboiler in the atmospheric pressure tower should have some extra capacity, but not too much. So, if the bottom temperature of the pressurized tower is low, it is either because the load is low or because the reboiler in the atmospheric pressure tower has too high a capacity.