vacuum release valve sizing. 1

[401laurent]

Hello,
I'm sizing the vent for vacuum tank in condition of cold spray after hot washing, Could any one help please giving the formulas for this calculation, the aire venting and the air inflow required, in order to size the vacuum valve.
the data given is: MAV(Maximum allowable vacuum)for the tank ( psi), Cold spray temperature (oF), cold spray flow (lbs/h).
Thanks.
Laurent.

 

[gr2vessels]

Use API 2000 applied for storage tanks venting.
Cheers,
gr2vessels

 

[Chance17]

I disagree that API-2000 is the correct sizing method.
The correlations were made years ago based on a sudden rain storm outside a hot tank. I believe the contents was hexane.
The tank is assumed to cool at 300F per hour.
API-2000 could apply if your water spray is outside the tank.

For inside the tank spray, you will have to do a heat balance.
Initially there will be a calculated volume percent condensible vapors.
The cold spray will cool the vapors to the dew point then condensation occurs (latent heat).
I would assume the cold liquid heats to within 15F of the vapor dew point temperature.
By heat balance
(Lb/hr)liq *(Cp)liq *(deltaT)liq = (Lb/hr of vapor condensed) * (vapor latent heat)
Solve the equation for lb/hr of vapor condensed.
Convert the lb/hr of vapor condensed to moles per hour.
Convert the moles per hour to equivalent air flow.
Add minimum 150% safety factor