100 Most asked questions by Chemical Engineers

download the ASKNORMLIEBERMAN APP http://h.fanapp.mobi/asknormlieberman1

Wednesday, October 7, 2015



When I increased crude tower bottom stripping steam from 1,200 to 2,500 lbs/hr, I increased diesel yield by 1,000 BSD at the expense of LVGO. Vacuum, in the vacuum tower, improved from 25 to 18 mm Hg. Yet, vacuum resid yield failed to improve. Why not?

Reduction in vaporization of diesel in flash zone of vacuum tower, off-set reduction in pressure:

·       % vaporized prop. to  (V/1 • 1/P)

1 comment:

  1. Hello. We have an issue coming in our preflash column when the feed rate is increased about 105% of the capacity of the unit. But the trouble shooting, basically flooding in the pre-flash column, that result in entrainment of crude in the overhead section, and increasing delta S is not predictable. Is coming after sometime without any reason apparently. Actually, we have 2 trains, similars, same feed line, and the issue is occurring in only one at the same time. Which could be the root cause? FYI. Feed rate 1220 T/hr Crude. SS MPS 4 t/hr. Temp. inlet 200 degC. Pressure 3.3 barg in preflash. From KSA, Manuel!