Ethanol content in the purified methanol obtained through methanol distillation

The maximum allowable limit is 50 ppm, with a normal maximum of 30 ppm.

1. Reduce the temperature of the circulating gas to lower the methanol content in it. A high methanol content in the recycle gas leads to a low conversion rate in the methanol synthesis reaction, and it facilitates side reactions that result in the formation of ethanol. 2. The CO content in the fresh gas should not be high. The CO content is high, resulting in numerous side reactions; increasing CO2 appropriately can help suppress the occurrence of ethanol-related side reactions. 　 3. If synthesis can reduce ethanol to 200PPM–300ppm, distillation is a more convenient method to use. The reflux can be increased, as well as the extraction under atmospheric pressure. If there is a side stream, it can be used for this purpose; if not, the discharge from the bottom of the tower can be increased. However, this method results in greater losses of methanol. 　 4. To reduce the ethanol content in methanol, the focus is on methanol distillation; by increasing the reflux based on the load of the distillation tower, efforts should be made to keep the area where ethanol is concentrated in the middle and lower parts of the distillation tower ； Increase the recovery of fusel oils and control the temperature in the middle section of the atmospheric distillation column, so that the ethanol-enriched zone is concentrated at the outlet for fusel oils ； Water is added to the pre-distillation tower to reduce the concentration of crude methanol; by diluting the ethanol present in the concentrated crude methanol with water, it is possible to control the upward movement of ethanol into the refined methanol during the distillation process.

The ethanol content in methanol recovery depends on the customer’s requirements. Some users have low requirements regarding the ethanol content, so there is no need to keep it at a very low level in order to save steam.

Our atmospheric tower is a packed tower without side-stream extraction; what should we do?

Is there a methanol recovery tower? If so, keep the temperature low; use three towers, and send the material from the bottom of those towers to the fourth tower. Fusel alcohols are extracted from the four towers.

The concentration of methanol can be measured online by installing appropriate hardware at the distillation outlet and establishing an on-site industrial model. A few years ago, the teachers in our project team worked on this project: victory: