1 reply to this topic

[Zohar]

Hello all,

I'm a senior student for Chem E, at the Technion, Israel.
We have a graduation project in which we need to design a process for manufacturing phthalic hydride. In this course we need to write a process package at the end.

My role in this book is the design of the heat exchangers.
Unfortunately we have a situation of 2 fluids that are exchange their heat and they are both at their vapor phase, so that I have something like 36K tubes... (when I switch between the shell and tube fluids I gat above 100K tubes...).
When I try to design it I get very low heat transfer coefficient (where the target is high U), and the same is for the heat transfer area.

My question is mainly if there are these kind of heat exchangers where both sides are in their vapor phase, and if not what can we do instead?

Another question I have is if you can give me a good reference for designing vacuum distillation columns? We separate the PA from water and other HC in a vacuum distillation column and we have some basic questions we hope a good reference will answer.

Thanx,
Zohar

[Zauberberg]

Heat transfer question:

It depends how much pressure drop you have available for heat transfer - for both fluids. Also, asyou stated, fluids are in the vapor phase. Does condensation of hotter stream occurs during heat transfer?
Basically, there are no problems in selecting the most appropriate heat exchanger application once when targets and constraints are known. What you can do at least is to provide more data in this thread, or to fill equipment datasheets and send to heat exchanger vendors.

Distillation:

Textbooks from Ludwig and Kister are good reference for vacuum applications as well. Another good resource is: http://kolmetz.com/index.html (look for technical publications). We don't know the composition and thermal condition of your feed, required product purities and other possible unit constraints, so we cannot be of much help.

Good luck,