Heat exchanger vacuum breaker?

[Liftingengineer]

I have been told to add a vacuum breaker to our exchanger to prevent condensate build up during times of low inlet steam flow. From what I have seen a vacuum breaker works by allowing atmosphere in during situations when the pressure in the exchanger is less than atmospheric. My question is, won't allowing atmosphere in allow corrosive Co2 and O2 into the steam?

 

[LCeballos]

From my view point, install a VB into exchanger has not sense. Because inlet of atmospheric air would cause more condensation for steam.

Regards

 

[SeanB]

Have to say that I have never heard that one before. I agree with you 100%.

 

[TJOrlowski]

The recommendation is correct, but the reasoning is wrong. Installing a vacuum breaker and/or air vent to the shell side of steam to liquid heat exchangers is always recommended by every major (and minor) manufacturer.

The vacuum breaker/vent should be used in accordance with the type of steam system you've got. The reason is to prevent steam hammer that may occur if residual condensate remains at the bottom of the shell after the steam regulating valve has closed.

THe reason to include it is not for when there is low demand, but when there is NO demand, and steam is not flowing. The breaker/vent helps prevent steam hammer (and damage to the tube bundle) from occurring when demand resumes, and the steam valve re-opens. If you have other measures in place to completely remove condensate from the shell of the heat exchanger when the steam valve is closed, then a vacuum breaker/air vent are not necessary.

-TJ Orlowski