The problems that occurred today
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Our unit started up a distillation tower today; it is a packed tower used for distilling methanol. The concentration of the feed material is 50%, and the designed feed rate for the tower is 4 tons per hour. When the technicians began the startup process, the feed rate was initially 2 tons per hour, after which the steam supply was gradually increased while the vent flow was set at 50%. After some time, the reflux rate decreased, and no product was produced. What’s going on here?
I. On-site inspection: 1: Observe the changes in tower pressure; if it continues to rise, it may be that the flow in the section from the outlet of the tower to the reflux tank is not smooth, or some blind plates left over from cleaning procedures remain in place at the sealing surfaces. 2: Compare the levels in the tower and the reflux tank to avoid misjudgment caused by false liquid levels. II. 1: Confirm from a process perspective whether the operating temperature has reached the value specified in the start-up plan. 2. Were you in too much of a hurry and overlooked the fact that it takes time from starting to heat up to obtaining the output?
At the beginning of operation, do not remove too much liquid from the top of the tower; keep it mostly in reflux, unless the liquid level is extremely high. The load is already low at startup, so this allows for an increase in the gas/liquid flow rate inside the tower. If too much is taken from the top of the tower, the composition at the bottom of the tower may become too heavy. The steam heating effect and the condensation at the top of the tower also need to be checked, to ensure that there isn’t too much non-condensable gas inside, which could lead to poor heat exchange. Waiting until the operations become stable before accelerating the external feeding to the minimum liquid level helps to achieve product replacement at an earlier stage.
At the start of operation, full reflux is required; production testing can only begin once full reflux is achieved and the analysis shows that the heavy components are within acceptable limits. Inverted groove
Thank you all, guys; I’ve learned so much from you!
1# 75468688: The extraction rate at the tower bottom at 50% load is set too high at 50%. Your reactor bottom liquid level won’t be able to be maintained.
Vacuum needs to be created. We used to have a methanol removal tower as well; during an accident, the valves weren’t opened and the methanol tank collapsed