[binzee]

HELLO!

I am calculating the relieving load for a PSV located at the overhed line of NAPTHA Stabilizer.The Service Fluid is Low Pressure Gas having composition of 75%Propane,10%Iso Butane and 15%n-Butane.The Relieving Pressure and Temp are 350psig and 225F.My problem is how can i calculate the latent heat of vaporization of this mixture at the given conditions.


THANKS

[pleckner]

You may get a lot of different opinions on this one so let me be the first. I would bring the liquid to bubble point at the relief conditions to establish the liquid saturation enthalpy. Then I would flash about 1% of the mixture. The latent heat would be the difference between the enthalpy of the resulting vapor and the liquid. The reasoning goes something like this. As you flash, the lights will come off first and as time goes by, the heavies. The latent heat changes accordingly as the liquid becomes more concentrated in heavies. The very first flash will tend to give you the most conservative value.