Analysis of the influence of the upper dry plate in the vacuum tower on the vacuum level
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My unit has recently been processing heavy crude oil; after atmospheric distillation, there is practically no oil in the first, second, and middle vacuum stages of the vacuum distillation tower. The vacuum level at the top of the tower has also dropped to 93–94. I would like to ask the experts here for an explanation, in theory, regarding the impact of the drying tray on the vacuum level. Thank you.
The fractional distillation efficiency decreases after using a dry plate; I’ve never heard of anyone operating with a dry plate for extended periods of time. Perhaps the filler tends to coking and accumulate contaminants.
The vacuum level of the short-time dry plate should not decrease, unless an interruption in the mid-stage reflux leads to an increase in the gas-phase load at the top of the tower.
A dry plate, as I understand it, has no liquid phase circulation. Possible reasons include low gas velocity, liquid leakage from the tray, insufficient reflux flow, and excessive extraction volume – all of which can lead to dry trays. I don’t know how the traffic for your Top-Down Loop is. In the case of dry plates, the heavier components in the gas rising to the top of the tower do not condense; instead, they move upward to the tower’s apex, increasing the load there and certainly leading to a decrease in vacuum level