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Heat Exchanger Tube or Shell side control

I have an application where I keep a hot water loop at a certain temperature. Hot water runs on the shell side, cooling water on the tube side with a modulating valve controlling flow. Most of the time there is little or no flow since the downstream process is constantly removing heat. Of course, now we see a problem with fouling due to low flow. Would it be better to modulate shell side flow with a three way valve? This flow cannot be restricted in any way, must be maintained full at all times. Thanks in advance

Reply to
MarkB.
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Is the fouling from biogrowth or silt?

David A. Smith

Reply to
dlzc1.cox

By installing a three-way valve on the shell side, you might eliminate the fouling on the cooling water side by allowing full flow all the time. However, the shell side may begin to foul because it will now have reduced flow.

So, this leads to some questions. Is it possible to reduce the capacity of the tube bundle?

If this is an emergency cooling system that must be able to meet full capacity, you could install a larger tank-type exchange system where the shell becomes the tank. You could then install two cooling bundles in the shell. One would be adequate for the "normal" condition with the other kicking in as needed and otherwise having no flow at all. The "no-flow" condition would eliminate silting.

Just some thoughts.

Reply to
basilnospam

Clogging was due to build up of phosphates, we feel from earlier water treatment or lack of. This exchanger has been in service for 5 years, no maintenance.

I am leaning towards shell side flow control because shell side water is closed loop and treated differently from cooling water(current tube side). Cooling water is simply tower water, open system, treated with biocide and corrosion inhibitors. thanks again, Mark

Reply to
MarkB.

Dear MarkB:

You might simply recirculate the shell-side outlet flow back to the shell side inlet. Use a recirculation pump like they use for solar hot water heaters. If "stagnancy" is the only issue... You might look at control of the pH in the shell side fluid.

David A. Smith

Reply to
dlzc1.cox

Stick an AMOT valve ahead of the cooler.

Rick

Reply to
Rick

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