Why must the pressure column in synthetic distillation be at 5–6 kilograms? Can’t it be at atmospheric pressure?

From the perspective of the atmospheric tower, the low pressure in the pressurized tower prevents the temperature from rising, and insufficient heat supply in the atmospheric tower affects normal operation.

It mainly involves raising the temperature under pressure; with a large number of trays in the distillation section, distillation is thorough, thereby increasing the temperature of the atmospheric pressure tower.

Currently, plants with a methanol production capacity of over 50,000 tons generally employ a three-column, double-effect energy-saving distillation process. The so-called dual-effect system utilizes the condensation heat of pure methanol in the pressurized tower as a heat source for the reboiler of the atmospheric pressure distillation tower; simultaneously, the reboiler of the atmospheric pressure tower serves as the condenser for the pressurized tower. This approach results in energy savings of over 40% compared to conventional atmospheric pressure distillation. As a heat source, it is necessary to ensure the quality of its steam in order to maintain an adequate temperature difference for heat transfer. Therefore, increasing the operating pressure of the pressurized tower raises the temperature of the pure methanol exiting that tower, thereby ensuring the required temperature difference for heat transfer and achieving energy savings.

Principle； The boiling point of a liquid is directly proportional to pressure; the higher the pressure, the higher the boiling point. Advantages ； 1. Reduce the load on the atmospheric tower. 2. Utilization of thermal energy, energy savings.

Process optimization is a challenging task; as mentioned above, changes in pressure and temperature can affect the reaction rate

If a pressure tower is controlled at atmospheric pressure, it is no longer called a pressure tower.

It is much easier to increase pressure during the production process than to increase temperature. In the double-effect distillation process, we modify one of the columns to be under pressure, thereby raising the temperature at the top of that column. The product from the top of this column is used as a heat source for the column operating at atmospheric pressure; this approach saves both cooling water and heating steam.

The pressure tower serves two purposes: 1) energy savings, and 2) improving product quality to a certain extent. If it operates at atmospheric pressure, then the main advantage of energy savings is lost

Principle； The boiling point of a liquid is directly proportional to pressure; the higher the pressure, the higher the boiling point. Advantages ； Utilization of thermal energy, energy saving. Increase production.

If the pressure in the pressure column is at atmospheric pressure, then the traditional two-column process can be used directly. The reason for using a three-column system is that the conventional methanol distillation process employs two columns, namely a pre-column and a distillation column. Three-tower distillation involves dividing the methanol distillation tower into a pressurized distillation column and an atmospheric distillation column, making full use of the methanol condensation heat in the pressurized column to achieve \"double-effect\" distillation. The three-tower process reduces steam consumption for distillation by over 40% compared to the traditional two-tower process; more than 1 ton of steam can be saved per ton of methanol produced. The amount of cooling water required is reduced by 50%, while the processing capacity of the plant increases by 10% to 20%.

The boiling point of a liquid is directly proportional to pressure; the higher the pressure, the higher the boiling point. Advantages ； 1. Reduce the load on the atmospheric tower. 2. Utilization of thermal energy, energy savings. 3. The liquid in the pressure tower flows directly to the atmospheric pressure tower, eliminating the need for a transfer pump.

Same as above, but there is one more point: improve product quality, as ethylene glycol can only be extracted under pressure.