Heat Exchanger Comparison

[lainey]

I am currently working on a project which involves using heat exchangers in a closed loop system to increase efficiency at the plant. Water flowing through the exchangers will be heated up by steam. The team wants to use flat plate heat exchangers, however, i was wondering the benefits of using these instead of another model. Can anyone help with the pro's and con's of the various types? Thanks,
Lainey

 

[MintJulep]

Pros:
Very small per unit of heat transfered compared to other types of exchangers.

Approach temperatures can be very close.

Can easily change capacity by adding or removing plates if your needs change.

Plates are available in wide variety of materials to match your fluids.

Easy to clean.

Cons:
Lots of seal area to potentially leak.

 

[Montemayor]

lainey:

Here are some of the common features of PHE's (Plate Heat Exchangers):

Pros
1) Will probably be the lowest capital cost investment/ft2; maybe as low as 50% of a conventional Shell & Tube.
2) Very high efficiency; outstrips the S&T in its high heat transfer film coefficents.
3) With the low price you also inherit a stainless plate construction; this helps in combating corrosion and scaling.
4) Requires no expansion joints for thermal stress release; the plates adjust themselves.
5) Simple to dissasemble and assemble;
6) You can add future heat transfer area with a minimal of cost.

Cons
1) Strange "creature"; your maintenance folks are going to have to adjust and be trained on how to repair and care for this type of unit;
2) The uniqueness brings with it a dependency on successfully installing and maintaining the correct gastket material that is compatible with the service. Otherwise leaks will develop in service. This is by far the most frequent complaint - although, in all fairness, it can easily be overcome by diligent instructions and training.
3) You have to store and maintain spare plates and gaskets in your warehouse that are not in keeping with "standard" heat exchanger parts. This takes getting used to.
4) PHE's are not competitive in all applications; however, in water service they are almost impossible to beat.
5) Most PHE's can't be mounted inside steel structures or skids because of their overhead maintenance requirements; they almost always wind up installed at grade level, on concrete pads or piers with drainage capability directly below them.

I hope the above summary is of help.


Art Montemayor
Spring, TX

 

[lainey]

Thanks a lot guys! That is definitely a lot of help!
Lainey