Setting Pressure on Relief valves on Water Cooled Panels

in summary, relief valves should be set between the operating pressure and the maximum safe over pressure.f
  • #1

I work in the steel industry, specifically in the melt shop department which operates electric arc furnaces. My question is that those electric arc furnaces have water cooled panels around the furnace, and I am trying to install relief valves on the panels. the molten metal and slag in on the side of the panels can reach 3050 F on the molten metal side. the panel have circuits of water running through them to cool them while making steel. we are trying to learn at what pressure should we set the relief valves to? basically we worry when the panel starts leaking and the water start to convert to steam in the panels. I attached pictures of typical panel. please let me know what are your thoughts on calculations for flow, pressure drop, pressure setting for relief valves. Alot of time the circuits in the panels have one outlet and one inlet. Thanks for any help.


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  • #2
I think more info might be needed to get more responses. You acknowledge that the boiling point of water changes with pressure which is a good start. Where does the heat go after the water takes it away (giant radiator, cooling pond etc.)? What is it's pressure rating? What pump or type of pump is used? How many btu's need to be dissipated? Or can be dissipated? I assume these panels are plumbed "in parallel". What diameter the pipes are and rough length would be needed to estimate head loss and flow rate.

just some thoughts to get the topic flowing
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  • #3
Who specifies, makes or supplies the panels? They should be designed to work at a certain working pressure and a maximum safe over pressure. The Pressure Relief Valve (PRV) will need to be set somewhere between the two depending how accurate it is and the consequences if it opens unnecessarily.

You also need to check the capacity of the PRV not just the operating pressure. For example in an emergency can the water escape fast enough to lower the pressure or will the pressure keep rising even with the PRV open! This is especially true if the water can boil and turn to steam when the PRV opens. You also need to think about where any water or steam will be vented. High velocity steam jets are no joke.

Steam explosions are particularly dangerous. It's not like being splashed with 100C water. When steam condenses on skin it delivers a lot of energy due to the high latent heat of vaporisation that water has.

To me honest your post fills me with horror. If these panels aren't being designed and tested to meet a carefully thought out specification I strongly suggest you bring this to the attention of whoever is the safety officer for the plant.
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  • #4
This is highly dangerous to try to engineer on an Internet forum. Please consult the vendor or a registered professional engineer.

Thread locked.

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