Sizing Vacuum Pump for Batch Distillation
Sizing Vacuum Pump for Batch Distillation
(OP)
We've got several processes which we perform vacuum distillation on a batch basis to remove solvents. In some cases we use Nash liquid ring, they are real work horses. In other cases it is a smaller Kinney vacuum pump.
I'd like to develop reasonable justification for what vacuum pump we use, and have a better understanding of what is actually required.
Does anyone have any know of any good resources they can point me towards for sizing a pump for this type of application? Google / search has been less than productive, and I'd prefer something more concrete that my personal gut feeling of bigger than a bread box, and smaller than a sedan.
I'd like to develop reasonable justification for what vacuum pump we use, and have a better understanding of what is actually required.
Does anyone have any know of any good resources they can point me towards for sizing a pump for this type of application? Google / search has been less than productive, and I'd prefer something more concrete that my personal gut feeling of bigger than a bread box, and smaller than a sedan.
RE: Sizing Vacuum Pump for Batch Distillation
Link
RE: Sizing Vacuum Pump for Batch Distillation
Unfortunately it isn't a selection guide, but a sizing guide for which I am looking.
An example might be, I have a 10,000 gallon vessel from which I want to distill off 2,000 gallons of MEK, over a 12 hour time period at some temperature, say 60*C. What would be the minimum size pump to complete this?
I've found some online calculators for determining time required, but they don't provide a sufficient explanation of how they function.
https://www.chemengonline.com/partner-content/vacu...
https://vacuu-lan.com/vacuum-drying-process-time-c...
RE: Sizing Vacuum Pump for Batch Distillation
RE: Sizing Vacuum Pump for Batch Distillation
Good Luck,
Latexman
RE: Sizing Vacuum Pump for Batch Distillation
Consider this resource to support your work.
note : I found your post confusing , the purpose of the vacuum pump is to pump non condensable material, not the solvent!
Between the distillation column and the vacuum pump you should have a total condenser to recover organic material . Solvent is not supposed to be carried over .
Good luck
Pierre
RE: Sizing Vacuum Pump for Batch Distillation
We have a vessel with a solution containing a solvent. That vessel is connected to an overhead condenser which drains to a receiver tank. Vacuum is applied to the receiver tank, the solvent evaporates in the vessel, is condensed, and caught in the receiver. Ideally the outlet of the condenser is cold enough that there is little lose to the vacuum system. Thank you for the link. I actually may already have this document. Let me start digging through it again.
Latexman,
There is no column. Hopefully my response to pierreick bettwer explains the configuraiton. Minimum pressure (vacuum) may vary depending on the process. In the example case, we may limit vacuum to 4 PSIA to limit evaporation of the solvent collected in the receiver.
Georgeverghese,
Unfortunately I have been less than successful in convincing the powers that be of the value of Aspen. I believe there would be significant value in performing the simulations as you've described.
My interest is in what the minimum capacity of a vacuum pump is necessary at a set pressure for the process at hand. If our pump gives us 300 CFM at 4 PSIA (21 inHg)and it works, that's great, BUT could we get by with a vacuum pump that is 100 CFM or 10 CFM?
Intuitively I think the volume of the head space is important (is it a 10 gallon tank or a 10,000 gallon tank?), as is vapor pressure, and rate of evaporation, etc.
Thank you all again for your time.
RE: Sizing Vacuum Pump for Batch Distillation
At 4psia, condensing temp is about 42degC for pure MEK, seems reasonable for cooling water as coolant in condensor
RE: Sizing Vacuum Pump for Batch Distillation
Plan for an opportunity when the equipment will be clean and dry, draw down the pressure, valve off the system and record the pressure rise over time. Use well documented equations to calculate the air leakage rate. Everything else you need can then be calculated with decent accuracy.
RE: Sizing Vacuum Pump for Batch Distillation
RE: Sizing Vacuum Pump for Batch Distillation
What is the solute in this case ?