High pressure fire relief - water

[MortenA]

I have got a vessel with a design pressure of 210 barg.

The fluid into the vessel is natural gas from an underground storage (formation not cavern) - water wet.

The vessel design pressure is higher than the well shut-in pressure so the relevant design acse is "fire".

My problem is that Pc for water is 220 barg - below 211 bara+21%=254 barg.

Now what heat of evaporation do i then assign?

at 210 barg the heat of evaporation is 453 kj/kg but it goes toward 0 at Pc=220 bar.

Should i just use the heat of evaporation at 210 barg?

Best regards

Morten

 

[TangoCleveland]

What formulas are you using for sizing the RV? Since you're in the supercritical region, it will act more like a vapor relief valve than a boiling liquid RV.

Larry

 

[MortenA]

Thats my point excactly!

But my questin was more related to how to calculate the load. I must check with regards to the RV - but i recon i will use the API steam famula (section 3.7.1 with a supreheat correction factor as for 3000 psi even thoug 210 barg+21% is 3700 psi?

Best regards

Morten