5 replies to this topic

[chem guy]

Hi,

I am a Final Year student and is currently working over the designing of Crude Vacuum Distillation Unit (CVDU) as a part of my final year project. For the production of vacuum, i am using a 3 stage ejector system, to produce 50 mm Hg (Absolute) Pressure at Column top.

I have done calculations for the 1st stage ejector, but downstream of it, is 1st stage Inter-condenser. This inter-condenser is supposed to condense Gas Oil and Steam vapors coming as a discharge from 1st stage ejector. I need to design it, but for it i am not getting suitable literature resources. All i get when i search over the internet are articles over vacuum condenser performance or general knowledge but not designing of it.

Vacuum condensers are essentially similar in basic construction with Shell and Tube Heat Exchangers, but are not designed like that due to the presence of both Vapor and Liquid Phases and condensation in vacuum. I have read some heat transfer books like "Process Heat Transfer" by D.Q. Kern etc. In it i have got designing of total condensers that work at atmospheric pressures while i have to design for a partial condenser working in vacuum.

My 1st stage intercondenser operating pressure is 76 mm Hg.

Can anyone guide me with an authentic literature resource for the designing of Vacuum Condenser??

I will be greatly obliged.

Thank You and Regards.

[katmar]

There should not be any fundamental difference between designing this condenser and a condenser for atmospheric or any other pressure. You mention the presence of two phases - vapor and liquid. Every condenser has two phases - vapor enters the condenser and (at least some of it) is condensed to liquid. You seem to imply that there willl be liquid and vapor coming from the first stage ejector, but there will be no liquid discharged from the ejector.

Do not forget that the main condenser will be between the column and the first stage ejector. Only the uncondensed vapor from this unit (plus any incondensibles) will go forward to the ejector set.

[chem guy]

Thank you sir for your reply.

With all due respect sir, in response to your line.....

".....You seem to imply that there willl be liquid and vapor coming from the first stage ejector, but there will be no liquid discharged from the ejector...."

I would like to say that i haven't said that liquid would be coming from ejector. I f you will read this line in my post...

"...This inter-condenser is supposed to condense Gas Oil and Steam vapors coming as a discharge from 1st stage ejector. I need to design it, but for it i am not getting suitable literature resources....."

You wouldn't have concluded that i mentioned about liquid thing from ejector.

[chem guy]

Please if any one can mention me suitable Literature resource.

Thank You.

[breizh]

Hi ,
Consider this resource .
Kern "process heat transfer" and Coulson & Richardson 's chemical engineering volume 6 could support your query.

Hope this helps .

Breizh

[katmar]

... due to the presence of both Vapor and Liquid Phases and condensation in vacuum.

This is what confused me. It's probably just a language thing.