4 replies to this topic

[mahmoud salah]

Hi every body
I want some help in the steps of sizing a plate and shell heat exchanger .

[ankur2061]

mahmoud,

Are you into manufacturing of PHE's? The sizing of PHE's is done by manufacturers such as Alfa-Laval, GE and otheres. As a client/purchaser/consultant you are only supposed to provide the fluid data (pressure, temperature, flowrate, density, viscosity, corrosive properties of the two fluids) & heat exchanged (heat duty) for the PHE.

No client/purchaser/consultant actually sizes a PHE since it is still a specialist item. You may mention standards to be followed in the specification sheet such as API 662.

Hope this helps.

Regards,
Ankur.

[wojtar]

Something may be found in the following literature:

1) "Heat exchanger design handbook" by T. Kuppan;
2) "Heat exchangers - selection, rating and thermal design" by Sadik Kakac, Hongtan Liu.

As far as I know, ASPEN TASC has a module for sizing plate heat exchangers. It also can be done using CHEMCAD sizing tool - CCTherm.

...as Ankur said, if your exchanger is going to work in reality I would leave selection to plate heat exchanger suppliers because of the following:

1) Heat transfer parameters depend on plates geometry. Since different suppliers have different types of plates, you never know what equation is to be used (I think they elaborated their own correlations);
2) Usually design made by plate heat exchanger supplier is very fast - they have sized many of such exchanger and have their own calculation software and a lot of experience.
3) It is likely that such hand made design, if applied, would be much more expensive.

Regards.

[ankur2061]

A recent post on "Design Standards for Plate Heat Exchangers" is worth having a look:

http://www.cheresour...__1

This should give some basic understanding on PHE's.

Regards,
Ankur.

[Zauberberg]

Mahmoud,

By years, designing PFE has become a partially revealed mystery - in a few years from now every EPC company will do the complete design almost independently from original equipment manufacturers, as it is the case for S&T exchangers - but only up to a certain limit.

Normally, whether you are within an EPC or Operator environment - you are not personally interested in the final, complete thermal and mechanical design of a Plate & Frame heat exchanger. Why? Because you are not the one who will fabricate the exchanger and confirm the performance requirements, and also give the guarantees that all process targets will be met during continuous operation. This means that you HAVE to rely on the manufacturer and his final design, whether you agree or not. And, in my opinion, this is not the most important part of the story. You want the exchanger to operate properly and as per design so that you can finally go home (after commissioning) or stay relaxed and enjoy without having any headache caused by improper exchanger design (as an Operator).

What IS important, in my opinion, is to accurately specify all the conditions that the exchanger has to cope with. For example, if you are in Offshore environment, you don't want PFE's around. Why? Because you are dealing with dirty, corrosive fluids, loaded with solids and particles that will ruin the exchanger (and your life). On the other hand, if you are in the gas processing plant, having streams completely dehydrated, sweetened, and filtrated, you would ask yourself: why to choose a S&T exchanger with total area of 3,000 m2 when you can do it with a PFE with 800 m2 heat transfer area. And there lies the true role of process engineer - just make the thing working 100% reliable.