The water solubility of pure methanol is not up to standard!

The reason for the unsatisfactory water solubility is that other impurities or heavy components form azeotropes with methanol, which are then carried to the top of the tower and further into the distillation column. Therefore, it is necessary to control the amount of water added in the pre-distillation column, with this amount generally not exceeding 20%. If power and steam consumption are not a concern, the amount of water added can be increased. Another approach is to control the temperature of secondary condensation in the pre-distillation column; this temperature can be raised slightly, but the downside is that it may lead to loss of methanol. The third method involves taking samples from the side stream of the distillation column; if heavy components enter the distillation column, it becomes difficult to achieve satisfactory water solubility for methanol, and the issue can only be resolved by increasing the amount of fusel oils in the side stream. You mentioned crystal particles; consider whether catalyst powder might have been introduced.

The problem of methanol’s water solubility is usually caused by light components or heavy components entering the methanol product. 1. At the pre-distillation tower, it is necessary to control the pH level (7.5–10.5), the amount of water added (18–20%), the amount of steam used, as well as the temperatures of the first and second cooling stages, in order to ensure that light components are removed from this stage and do not enter the main distillation tower. 2. In the pressure distillation tower, it is important to control the reflux properly, so that heavy components do not rise to the top of the tower. 3. During startup and shutdown operations, it is essential to follow the established procedures carefully, to prevent heavy components from reaching the top of the tower at the beginning of operation; even if the temperature and pressure are adjusted appropriately, the water solubility issue may persist for a considerable period of time. 4. The crystalline substance you mentioned is likely some kind of wax, formed as a result of the solidification of waxes during water-solubility tests. It is necessary to control various parameters by continuously performing cyclic washing on the pressure tower to remove the heavier components.

Uh, thank you! We’ve solved this problem! Our catalyst is also at the end of its life! I tried every method during those days! The water addition amount and the temperatures for the first and second cooling stages have all been adjusted! In the end, it worked properly after being restarted once!

Towards the end of the catalyst’s life, rising temperatures increase the amount of by-products.

At the end of the catalyst life, there are more by-products.

The 3rd floor has experts; the rest are just talking nonsense