Three-column distillation operation of methanol
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I would like to ask for advice here regarding the triple-column distillation of methanol – how can we ensure that the production volume remains constant throughout each shift? Recently, there has been competition over production levels, and the skill level of the staff is limited; it seems that the production volume is somehow “lost” during shift changes. What should be done in this situation? Apart from the feed flow rate, the liquid levels in all tanks are within normal ranges. Some people suggest extracting the methanol from the towers in advance. I hope those who are experts in distillation can give some guidance
Before counting the production for shift handover, slightly open the production valve
There is a liquid level limit; it cannot be below the lower threshold
Control the liquid levels in the three towers; after ensuring product purity, pay attention to the liquid levels in the atmospheric tower and the distillation tower.
For calculating the production volume in three-column distillation, it depends on how you measure that volume. If you use a flow meter to determine the production volume, make sure that the flow meter can handle high flow rates； If you calculate production using the inventory method, you need to take into account your liquid level measurements; it is necessary to explain the situation in order to determine how to achieve the desired production level. If the feed rate and the crude methanol content remain constant, then increasing the production volume is achieved by controlling the level of the reflux tank and the reflux ratio.
Towards the end of the shift, trying to increase production slightly by lowering the liquid level in the return tank for a short period of time is not a proper way to act; it’s not fair to take advantage of one another between shifts. It is also constrained by the load and capacity of the upstream synthesis unit, as well as the level of the crude methanol tank.