main things to be concerned in designing a Plate heat exchanger 4

[821326]

I am having a design issue where a Plate heat exchanger to be designed and fabricated for the following requirements.

* heat transfer takes plate from hot diesel burnt flue gas(700 oC)to normal air(200 oC) both media is at 1 bar pressure.
* heat load is app. 70 kW
* flow rates in the flue gas is 140m3/min and air 430m3/min.

i have done some basic theoritical calculations to find overall heat transfer coeff. and the Heat transfer area.

but what i want to know is, how to select the suitable material(specific grade of Stainless steel ), optimum spacings between the plates, how to fabricate the heat exchanger; most suitable fastening techniques to withstand the thermal expansions and stresses in the operation, wheater to make it as a complete undetachable unit which is welded among the plates.

i am looking for replys fome all who can kindly help in this case.

thanks........
best regards
chaminda

 

[rmw]

Look this site over. Don't invent a new wheel. Others have already invented it.

http://www.bdheat.com/bd/airpr/airpr.html

rmw

 

[rjw57]

I can tell you that based on my experience, your temperature difference across the heat exchanger is probably going to be problematic. You will more than likely tear the welds between the cold and hot side plates thereby causing cross leakage if you are considering a brazed plate heat exchanger. I attempted to use these in similar temperature applications when working with fuel processing systems to recover energy from the anode tail gas oxidizer for use in raising steam for the process. My recommendation is that you go with a tube-in-tube design since it is much better suited for this type of application. Try Exergy LLC

http://www.exergyllc.com/

as your first contact as I know for a fact that they can do what you need.

 

[doublebend]

RJ- Exergyllc is the one company that we have been speaking to about applying our bending system to their duel tube heat exchangers.Slow going, test have not occured yet.They are a few miles from us on L.I.
821326
You can ask if they have tested the Wolfbend system. I'll be speking to them this week.If after veiwing their products post any furhter questions you have I may work it in to the conversation.

Steve Wolf
Wolfbend LLC

http://www.wolfbend.com