Help on defining TEMA Class exchanger

[dimeivan]

I need to specify a water cooled exchanger.
The problem is that I have an elevated temperature difference between tubeside and shellside, and temperature cross.

The conditions of service are as follow:
Tubeside - high pressure N2/H2 mixture (gas, no condensation) 6868 kg/h, Tin/out= 168/40ºC
Shellside - cooling water, 44900 kg/h, Tin/out= 32/48.2ºC

As shown, temperature cross put multipass exchangers out of the question. I do not want to use F shells either because of thermal expansion issues. Expansion joints in E shells are not allowed by client´s design practices too.
Increasing water flow is not feasible either because of supply limits.

The only solution I forsee are multitube hairpins, but my client strongly prefers TEMA hxs.

Has anyone a practical TEMA solution to this? Have in mind that multiple one-pass shells do not solve the thermal expansion issue.

Many Thanks

 

[tickle]

I guess you need a BFU. The U has no thermal expansion issues and negates the requirement for bellows.

 

[dimeivan]

I have ruled out F shells, their foil strips are prone to damage upon the first bundle removal. I think I will stick to two or three 2-pass AES shells connected in series.

Thanks anyway!

 

[chemjock]

Cooling water is usually put on the tubeside.

 

[dimeivan]

Not quite, I have high pressure H2 (4000 psig), so I have to send it through the tubes.

 

[Christine74]

You want an exchanger with sa plit backing ring that withstands 4000 psi internal pressure?

I don't think you'll be able to find a fabricator.


-Christine

 

[dimeivan]

You are right Christine, thanks for the advice, I think a CEU configuration will do the job.

 

[Christine74]

Note that if you were to go with a "U" tube bundle and use 4 or 8 passes on the tube side (with the "U" bends wrapping around vertical centerline), you might be able to specify that the longitudinal baffle be welded into the shell, that way you'll be able to have achieve a temperature cross without having the seal strip issues associated with conventional TEMA F shell.


-Christine

 

[dimeivan]

That´s a nice one. But if I have a 16" shell, how is someone going to fit into it so as to weld it?

 

[Christine74]

16" is way too small to fit a welder inside. You'd probably more like 44" to do that.

Looks like you're going to need to use two exchangers in series.


-Christine

 

[dimeivan]

Yes, it seems I have no other choice.

 

[MrBTU]

A rack of single pass NEN's with flanged and flued exp joints on the shell.

 

[MJCronin]

Please, be polite... remember to complete the thread and keep us informed of your final choice

Best Regards

-MJC

 

[dimeivan]

I thought I already did... I opted for two 2-pass(tubes) CEU shells in series.

Thank you all for your kind advice.

-Ivan