Selection of right Pump for Vacuum column

[rock3x]

I am new to used Oil refining.In my plant we are using Vacuum Distillation so i want to know the right type of pump for our circulation pumps(centrifugal).How can i make the calculation for that according to column dimensions.

 

[TD2K]

I'm not sure what you are asking. The column dimension by itself is not a factor in sizing your pump. The heat and material balance for the unit will give you the required flow plus any design margin you want to add. The heat and material balance will also provide you with the physical properties for the pump data sheet (density, viscosity, etc). The hydraulics of the circulation loop composed of the piping, equipment and elevation determine how much head you need.

 

[rock3x]

But in our case there is some instrumentation problems(unfortunetly right now we cannot find any solution for this because of some administation problems) are there so the operetor cannot see the level in the column he is running the pump according to pressure in the pump but all the time it wont work properly once the pump got starved with out material it is taking too much time to get started again even if the suction head is there(Remember ours is Vacuum system) it is affecting the mechanical seal of the pump regularly thats why i have doubt in the efficency of the pump if we release the vacuum from 760mmHg to around 300mmHg automatically the pump will get pressurize once it started the pressure,Ciculation rate everithing is ok for our process.

 

[TD2K]

"some instrumentation problem" isn't very clear.
What do you mean by(unfortunetly right now we cannot find any solution for this because of some administation problems)

Is this a draw tray for the LVGO or HVGO? Are you running your draw tray dry when you say "operator can not see the level in the column"?

It's going to help a lot if you can provide a sketch and some details of the system and the problem.

 

[MJCronin]

Rock...

I suggest that you break your response into sentences.

Who originally specified these pumps ? Are datasheets available ?

Are there pump NPSHa calculations or even pump curves available to you ?

Or did an MBA tell you that the unit purchased from another company and all records, operating manuals, pump curves etc were discarded by the previous owner ?

 

[rock3x]

Our processing Vacuum is 760mm Hg.The problem is that the pump which we are using in our Vacuum column is not getting pressure in 760 mm Hg because of high vacuum.The material from column is not coming to the pump suction line due to high vacuum or in other words pump doesn't have the power to draw the material from this high vacuum .If we are reducing the vacuum to 300 mm Hg pump will get pressurize.

Is it because the wrong selection of the pump?

If so is there any solution to find the right pump?


Sorry for the late replay.

 

[RaRo]

I may ask the obvious, but can you install the pump on a lower floor?

 

[StoneCold]

How about making a sketch of what you have, with dimentions and pipe sizes and then maybe we can help you out.
Vacuum columns can be difficult, you are often trying to move boiling point liquid. As RaRo points out, increasing your liquid head above the pump is an excellent way to overcome some of the problems.

Regards
StoneCold