The problem that distillation atmospheric-pressure columns cannot increase production capacity

What type of distillation tower do you have? Your reflux temperature is also too high. I’m not sure whether your coolers are water-cooled or air-cooled; if they are water-cooled, could the cooling effect be insufficient, or is it possible that the system is operating under overload conditions? The pressure at the top of the tower is too high. Is the excessive methanol level at the bottom of the tower due to an excessive feed rate, or is it because the load on the pressurized tower is low and the temperature is low, resulting in a high alcohol content in the material fed to the atmospheric pressure tower? I wonder what temperature control is used at the bottom of your atmospheric pressure towers?

This phenomenon is a typical case of overload. When the load increases, the temperature in the stripping section drops due to insufficient heat supplied by the reboiler ； The capacity of the top condenser is insufficient, which results in the purified methanol not being cooled to the required temperature; as a consequence, the temperature in the distillation section rises, and it becomes difficult to achieve the desired quality for the purified methanol. Additionally, is the operation of the atmospheric pressure tower stable?

1. What is the temperature at the top of your tower? 2. The reflux temperature is too high; if it exceeds 64.5 degrees, it becomes gas and can no longer serve as a reflux stream. 3. Do you use air cooling or water cooling? It is recommended to increase the cooling area of the atmospheric pressure tower and connect a shell-and-tube heat exchanger with a surface area of around 40 square meters

What type is used for the internal components of the tower? Some trays have limited operational flexibility, and the above phenomena occur when the load changes

The lower part of the tower is equipped with floating valve plates, while the upper part contains structured packing. The cooler uses circulating water; the water supply pressure is 0.35 MPa and the temperature is 13 degrees.

How high is the cooler installed? Is the circulating water taken from the main pipe?

When the atmospheric pressure tower operates at an increased load, the temperature in the stripping section of the tower decreases while the temperature in the distillation section rises. The reflux temperature is 69 degrees, and the top pressure of the tower is 0.04 MPa. The methanol content in the residual liquid exceeds the specified limits. What could be the cause of this, according to experts? The main factors affecting the quality at the bottom of a distillation column are: 1) feed rate and feed temperature, 2) bottom temperature and pressure, 3) bottom product withdrawal rate. The main factors affecting the quality of the distillation column’s top product are: 1) feed rate and feed temperature; 2) top temperature and pressure; 3) amount of product taken from the top or the amount of reflux; 4) reflux temperature. I understand that by \"excessive methanol levels\" you are referring to the quality of the product taken from the bottom of the column, but based on what you’ve mentioned it seems to be about the top product as well. Therefore, here are a few suggestions for addressing issues related to the quality of both the top and bottom products, for reference only. When the feed rate increases (the production load rises) and the quality of the overhead product is not satisfactory, the measures that can be taken include: 1. increasing the feed temperature, 2. increasing the reflux volume, 3. raising the overhead temperature, 4. increasing the reflux temperature, 5. adjusting the feed location (distillation columns usually have three feed inlets). When the feed rate increases (the production load rises) and the quality of the product at the bottom of the tower is unsatisfactory, the measures that should be taken are: 1. Increase the feed temperature, 2. Increase the temperature at the bottom of the tower, 3. Reduce the amount of product taken out. The above measures can be adjusted one by one; if adjusting just one measure doesn’t work, two measures can be adjusted simultaneously. There are no better techniques for operating distillation towers; one can only gain production experience through trial and error.

The feed alcohol concentration is too low, and the reflux is too high

Thank you all. The cause has been identified: it was due to an insufficient circulation volume of the circulating water. Starting one more circulating water pump resolved the issue.