Pure methanol product

Reply to 1# maju16-054: The main reason for the unsatisfactory oxidizing capacity is that the number of trays above the refined methanol extraction point is no longer sufficient to remove residual light components. Means to avoid this: carry out extractive distillation in a pre-tower, control the condensation temperature at the tower top, increase the reflux ratio in the main tower to prevent light components from rising; more importantly, continuously and effectively remove the heavy components ； However, the reflux ratio cannot be too high; an excessively high reflux ratio can cause the light components to move downward, which may sometimes affect the oxidizing capacity of pure methanol. Whether distillation operations can improve oxidizing capacity depends mainly on the quality of crude methanol! ! !

①The light components at the top of the tower are high; increase the extraction amount (water) in the pre-tower and appropriately raise the condensation temperatures of the two stages in the pre-tower； The initial distillate is appropriately taken from the pre-tower condenser. The water addition rate in the pre-distillation tower is kept low, resulting in poor extraction efficiency; generally, the water addition amount is 20% of the feed volume, which reduces the recovery of CH compounds. The control of the condensation temperature at the top of the tower is related to the use of catalysts; at the beginning of catalyst use, the condensation temperature is generally maintained between 30–40°C, as this stage sees fewer impurities in the crude methanol, and there are also fewer volatile impurities. Towards the end of the catalyst’s lifespan, the impurity content in crude methanol (volatile components) increases, so it is necessary to raise the temperature of the condenser to ensure that all volatile components evaporate. ②The reflux ratio is low; increase the reflux volume. Increase the reflux in the main tower and strictly control the temperature of the sensitivity plate to prevent heavier components from moving upward (but do not increase the reflux too much, to avoid lighter components moving downward). Extract some of the initial distillates from the secondary reflux tank of the pre-tower ； Increasing the main reagent reflux ratio helps prevent the upward movement of heavier components; however, an excessive increase in the reflux ratio can cause lighter components to move downward, and this may sometimes affect the oxidizing capacity of pure methanol. This is because the number of trays above the outlet for pure methanol is no longer sufficient to remove the remaining lighter components. Extracting a small amount of the initial distillate from the reflux liquid can effectively improve the oxidizing capacity of pure methanol. ③The extraction temperature is high; reduce the extraction temperature. ④Less middle distillate is recovered, which increases the processing load on the recovery tower and raises the amount of fusel oils obtained. In the main distillation tower, less heavy-component fusel oil is recovered, which also affects the oxidizing property of purified methanol; in such cases, it is necessary to increase the amount of fusel oil recovered. 5 Crude methanol has poor quality and contains many impurities. Adjust the process conditions in the synthesis section to improve the quality of crude methanol. ⑥The large feed rate results in an unstable liquid level at the bottom of the tower, leading to uneven feeding and poor separation efficiency