What are the indicators that affect the quality of pure methanol?

1. What are the factors that affect distillation operations? Answer: Apart from equipment issues, the main factors affecting the distillation process include the temperature and pressure in the tower (including at the top and bottom of the tower, as well as on certain trays that are of particular significance)； Feeding status ； Feed rate ； Feed composition ； Feed temperature ； Steam rise velocity in the tower and heating capacity of the evaporation kettle ； Return flow ； Top condenser cooling capacity ； Top draw and bottom draw. The operation of the tower involves adjusting these influencing factors in accordance with the composition requirements of the products at the top and bottom of the tower. 2. What is the impact of changes in the operating pressure of a distillation tower on the distillation process? Answer: The design and operation of a tower are based on a certain pressure level; therefore, in a typical distillation tower, it is necessary to maintain a constant pressure at all times. Fluctuations in column pressure will have the following effects on column operation. (1) Impact on product quality and material balance: Changing the operating pressure will alter the composition of the gas-liquid equilibrium on each tray. As the pressure increases, the heavier components in the gas phase decrease, thereby increasing the concentration of the lighter components in the gas phase ； The increase in the content of light components in the liquid phase also alters the weight ratio between the gas and liquid phases, resulting in an increase in the liquid phase volume and a decrease in the gas phase volume. The overall result is: the concentration of light components in the tower top distillate increases, but their quantity decreases relatively ； The concentration of light components in the reactor liquid increases, and the volume of the reactor liquid increases as well. Similarly, as the pressure decreases, the amount of distillate at the top of the tower increases, while the concentration of light components decreases ； The volume of the kettle liquid decreases, and the concentration of light components drops. Under normal operation, a constant pressure should be maintained; however, if abnormal operations lead to an increase in the concentration of heavier components in the product at the top of the tower, it is possible to raise the operating pressure appropriately to ensure that the product quality remains satisfactory, but this will result in an increased loss of lighter components in the liquid phase. (2) Changing the relative volatility between components: As pressure increases, the relative volatility between components decreases, resulting in a reduced separation efficiency; the opposite is true as well. (3) Changing the tower’s production capacity: An increase in pressure and an increase in the specific gravity of the components lead to an increased processing capacity of the tower. (4) Fluctuations in tower pressure will cause confusion in the corresponding relationship between temperature and composition. In our operations, we often use temperature as an indirect criterion for measuring product quality, but this is only correct when the tower pressure remains constant. When the column pressure changes, the dew point and bubble point of the mixture change, which in turn alters the temperature distribution throughout the column; the relationship between temperature and product quality also changes as a result. Based on the above analysis, changing the operating pressure will affect the performance of the entire tower; therefore, a constant pressure should be maintained during normal operation. Only when the normal operation of the tower is disrupted can the pressure be adjusted appropriately, within the limits permitted by the process parameters, in accordance with the analysis outlined above. It should be noted that during distillation operations, changes in the feed rate, feed composition, and feed temperature; changes in the heating steam supply to the bottom of the tower; changes in the reflux volume, reflux temperature, and coolant supply at the top of the tower; as well as blockages in the tower plates, can all cause fluctuations in tower pressure. In such cases, it is necessary to first analyze the causes of these pressure fluctuations and take appropriate action to restore normal operation. 3. What is the impact of the feed condition on distillation operations? Answer: There are five types of feed conditions (1) cold feed ； (2) Bubble-point feeding ； (3) Gas-liquid mixed feed ； (4) Saturated steam feed ； (5) Superheated steam feed. For ease of analysis, let δ be the heat required per kilomole of feed liquid to become saturated vapor, where δ equals the latent heat of vaporization per kilomole of feed. It can be seen from the above equation that δ > 1 for cold feed, δ = 1 for feed at the bubble point, and 0 for gas-liquid mixed feed

The friend upstairs gave a very comprehensive answer; hehe, there are so many factors that can affect the quality of pure methanol during production

This depends on one’s own production situation; generally, the impact is unpredictable.

Simply put: reflux ratio, reboiler temperature, pressure difference in the tower, etc