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What should be the optimum operating pressure for preflash drum at CDU

What should be the optimum operating pressure for preflash drum at CDU

What should be the optimum operating pressure for preflash drum at CDU

We have a preflash drum at our CDU, but it operates at 9 kg, where there is no vaporization. the top line of the drum is connected to the flash zone of the atmospheric column. we are now reducing the pressure of the preflash drum in order to get the light component directly to the atm column. Is there a lower limit for the pressure, or any criteria that should be kept in mind when reducing the pressure?

Thank you for your replies.

RE: What should be the optimum operating pressure for preflash drum at CDU

Ideally, you need to remove lighter components that would otherwise appear as vapor phase upstream of the CDU heater, at End-Of-Run conditions.

In simple words, simulate maximum temperature and the lowest expected pressure you will get downstream of the hot preheat train (upstream of the furnace) and see what vapor fraction you are getting. Then do the work backwards, and see what pressure you need in the preflash drum to get rid of those components. However, bare in mind that your preflash drum has a certain vapor handling capacity and, if you go beyond that point, it could result in entrainment of liquid.

I assume there is a crude booster pump to transfer liquid portion of the feed from the preflash drum bottoms.


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