1 reply to this topic

[cea]

Dears,

 

I have come across situation, wherein I am required to explore various scenarios for calculating PSV capacity for vessel that is operating under vacuum.

Apart from fire case, I have learned that ejector motive fluid (steam) may get entrained into process side, if the steam pressure drops below its “pick-up” pressure. In that case, this could be additional scenario.

Please suggest if such scenario is credible one & in that case, the procedure to estimate PSV capacity for the same.

 

Thanks & Regards

[fallah]

cea,

 

In stable operation of an ejector, the discharge pressure is always lower than the pick-up pressure. When the discharge pressure drops below the pick-up pressure the steam may get entrained into process side and existing vacuum might be broken rather than overpressurizing the vessel!.

Till now, to estimate the capacity of relevant PSV it could just be said the a.m. scenario is applicable; but without having adequate info and especially sketch of the system one cannot help anymore in this regard...