steam/water heat exchangers volocity wear
steam/water heat exchangers volocity wear
(OP)
we are making our own heat exchangers to save money and teach inmates a skill, my question is reguarding volicity wear on our pipes. we use type k copper and have a problem with it being destroyed at the incomming water point, the rest of the exchanger wears well. Is there a beter tube material and were do you get it? Is there a "paint on" abrasion resistant coating around? Would applying silver solder to the pipes at the water entry hurt or help? The original exchangers made by Paterson Kelly have the same problem with wear at the water entry point, I'm not sure what material they use, but it does not hold up any better.





RE: steam/water heat exchangers volocity wear
I assume that you are staying with Cu alloys for ease of working with them.
Let me know if you want to talk stainless steel.
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Plymouth Tube
RE: steam/water heat exchangers volocity wear
RE: steam/water heat exchangers volocity wear
Water quality also affects the wear rate.
The problenm occurs only at the inlet because as water entgers a tube inlet, the streamlines converge into a flow area minima called a "vena contracta" which has an effective flow area of only 64% of the measured open tube area. The velocity at the centerline of teh tube inlet will be about 160% of teh average velocity, and so will the velocity of water in the recirculating eddies near the inlet. The vena contracta can be eliminated by use of an inlet bellmouth.
RE: steam/water heat exchangers volocity wear
The trade off with stainless is that you can use thinner walls because it will resist erosion and it is stronger. This will offset most of the performance difference.
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Plymouth Tube
RE: steam/water heat exchangers volocity wear
Second, is this a shell & tube type exchanger and is your erosion ocurring on the tube or shell side?
Maybe some impingement protection is needed.
Regards,
Mike
RE: steam/water heat exchangers volocity wear
I was going to suggest tube liners. Is that what you are referring to by the term bellmouth?
rmw
RE: steam/water heat exchangers volocity wear
RE: steam/water heat exchangers volocity wear
A third approach sometimes used is a distributor belt, a short, larger shell containing the inlet nozzle, mounted outside the main shell which has cutouts to admit the flow to the bundle. This increases the inlet area to the shell and reduces the velocity of the fluid. Sorry, I don't have any pics or so forth handy to post at this time.
Can you provide some further details of your designs, maybe tube layouts, shell and nozzle diameters, flow rates, etc? It might then be possible to make some calculations, etc. to compare to industry standards.
Do you have any data from the manufacturers you list, to compare your operating conditions to?
My guess (and a guess only) is kind of that your flowrates and therefore fluid velocities are above what the original equipment, which as I understand it, you are "copying", was designed for, leading to the erosion wear you mention.
Regards,
Mike