Analysis of the reasons for unqualified products in triple-column distillation

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I. Issues related to the parameters of crude methanol: On this matter, there is basically nothing we can do; apart from controlling the temperature and pressure during synthesis, there are no other solutions. I. Incomplete pretreatment in the tower: 1. The amount of water added is about 15%, which is essential – sufficient water ensures complete extraction. When the product quality is poor, adding an appropriate amount helps; beyond 20%, the effect is minimal. 2. If enough alkali is added, the pH at the bottom of the pre-treatment tower can be maintained between 7 and 8, or between 7 and 9 as well – that’s no problem. In addition to preventing corrosion, alkalis can react with certain insoluble organic substances, which helps in the purification of methanol. 3. Top and bottom temperatures of the tower. If it is too low, the removal of light components will not be complete. 4. The liquid recovered from the exhaust gas treatment unit cannot be discharged directly into the reflux tank; it is better to send it to a separator so that the light components can be removed from the system directly. II. Issues related to the products of the pressure tower: 1. Reflux – this is essentially the only way by which we can control the products of the pressure tower. 2. Temperatures at the top and bottom of the tower. If it’s too high, the heavier components move upward, which is a **problem**! ! III. Products from atmospheric pressure columns 1. Reflux: The amount of reflux determines the temperature; generally, we use reflux as it helps with purification. 2. Side-stream extraction: This is what impressed me the most. Increasing the amount of product extracted does increase the load on the recovery column, but it has only advantages and no disadvantages. More importantly, it is necessary to control the temperature of the material extracted from the side lines, as this allows for the removal of components that we do not want. Of course, it is first necessary to determine what factors affect the product, identify its relevant physical properties, and then control the temperature in order to remove those unwanted components. 3. Temperature: The temperature at the top of the tower must certainly not be allowed to rise too high. As for the bottom of the tower, we prefer it to be higher, as this not only reduces waste but also makes it easier to control the temperature of the side streams. If the steam volume remains constant, the liquid level is the best control method