2 replies to this topic

[WilliamN]

Dear peer professionals,

My question is some what heat transfer related. Please forgive me if you think this is not a good fit for this forum.

 

I have an existing shell tube exchanger, using 90 psig steam to heat up potable water (used for safety shower for winter time). Steam flow is controlled by a 1" control valve to maintain potable water to ~80F.

We are planning to replace this shell tube exchanger with a double wall plate frame exchanger. But this type exchanger has a temperature limit ~350F, thus I can not use 90 psig steam. I found a lower temperature medium - condensate with temperature 240F.

 

My question to the peer group is , can I move the control valve from steam line to condensate line? since the cold side is the same stream and I just switched the heating medium, it will save  big money if I can keep the control valve.

 

Thanks.

[Bobby Strain]

At 350°F the saturated steam pressure is 120 psig.

 

Bobby

[Pilesar]

The cost of a 1" control valve is not usually considered "big money" on a project to replace a heat exchanger. How much do you estimate it will save? It is unlikely your existing control valve will allow sufficient condensate flow if it was sized for steam. You can determine your required flow and size the control valve yourself after a bit of training. Your low pressure water application should be pretty straighforward. I suggest having an engineer lead you through the calcs or at least check your work if you are going to size a critical valve. Valve manufacturers routinely supply sizing software for free download. Alternatively, the valve vendor might do the calcs for you if you supply the stream information.