Unconventional Control for distilation column

[exclamation]

For revamp of our refinery we are installing a parrallel crude distillation column ,now the problem with it is the control scheme .you can see the scheme in the attached file .

one distillation column operates at 30 % and other is at 70 % of total capacity .Now the draw nozzle for pump around and side stripper is common .
For pump around the draw is measured and regulation by a FCV from both column and is then enetred back in the column in the same quantity they were drawn .
Now my concern is that the liquid is at equilibirium and may flash even if additional static head is available ,which can cavitate the pump

Can any one propose alternate scheme

 

[CJKruger]

exclamation, I think it is a terrible idea and recommend you install another pump and keep the suction piping separate and without control valves and flow meters.

 

[TD2K]

I never like to put a control valve on a pump suction and especially in a service like this where the liquid being drawn off the tower is at bubble point. You'll have to try to balance static head and line losses against control valve dP.

Don't do it, add some more pumps. If you want to minimize cost you can have a pump for each tower with a common spare and the appropriate valving to allow it to be put into either service.