×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

TEMA Type BFU Shell and Tube Heat Exchanger

TEMA Type BFU Shell and Tube Heat Exchanger

TEMA Type BFU Shell and Tube Heat Exchanger

(OP)
I understand that a F shell TEMA type heat exchanger is specific to thermal designs where there is a temperature cross. Is it possibly that the temperature difference between the shell side inlet and outlet temperature be to great for this type of design? For example: Lets say my fluid temperature on the shell side inlet is 100 deg. F and on the outlet it is 900 deg F. With fluids and temperatures separated by the longitudinal baffle in the shell wouldn't that cause the upper half of the shell to thermally grow at a different rate than the lower half thus creating a moment on the shell flange that connects to the tubesheet?

The moment created at this bolted connection could potentially cause a leak at that joint.

Thanks!

RE: TEMA Type BFU Shell and Tube Heat Exchanger

See article: https://s3-ap-southeast-1.amazonaws.com/erbuc/file... It discusses some of the merits of F-shell exchanger.

Your application does look extreme, with 800 deg (F?) temperature difference of the shell-side fluid. Typical temperature difference limitations I have come across are in the range 300-450 degF but thermal stress analysis should confirm the right figures for this particular application. There are some tips from Gulley's:

http://www.gulleyassociates.com/news2002.htm#Dec02
http://www.gulleyassociates.com/news.htm#Dec96

I doubt one single exchanger can be designed to manage this Delta Temperature.

Dejan IVANOVIC
Process Engineer, MSChE

RE: TEMA Type BFU Shell and Tube Heat Exchanger

Agree with the above, but for a different reason than just the delta t.

Physically, the kind of design you seem to be thinking of would be a sheel and tube, U-bend tubes since you seem to be thinking of the differential expansion between top and bottom of the tubesheet stressed at the (horizontal) dividing plate. That can be avoided by a once-through HX so the colder outlet end is at the far end from the (very hot!) inlet end.

But if it were a u-bend tube, or a turn-around head at the far end, why would either of those "help" the original design intent? Your second process fluid - it can't be cooling water since you want to increase shell side temperature from 100 inlet to 900 outlet, but might be steam, right? But them you'd get a real nasty transition points inside the tubes as the water condenses at various points along various tubes randomly. Very, very hard to control for your process, very hard to control for the steam flow too. Seems like your end head would be mixing some tubes with steam, some with water mixes, some with all water and all flashing back and forth. And U-tubes would be even worse. A non-condensing liquid in the tubes might work.

Regardless, the extreme temperature difference across the shell side requires baffles or multi-shell side entry points to "even out" the delta T between both fluids. Try using two or three heat exchangers in series instead.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources