Determination of the over-vaporization rate in lubricating oil-type vacuum distillation columns
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In lubricant-type vacuum distillation columns, some heavy components are stripped off in the bottom stripping section; should this amount be deducted when determining the vaporization rate?
I think it should be subtracted so that the calculation is accurate
The main thing is to ensure that there is a certain amount of internal recirculation in the packing at the lowest section of the vacuum tower, thereby preventing coking in that packing
There is no need to subtract anything; ensuring internal recirculation in the washing section is sufficient. Furthermore, the amount of vapor generated at the bottom of the vacuum tower is very small. One can take a look at hydraulics; the backflow rate in the washing section is essentially equal to the amount of vaporization.
It should not be deducted; most of this heavy vaporized fuel will condense into droplets and fall back to the bottom of the tower, and this is how the internal recirculation below the washing section is formed.