Introducing liquid propane in ethane vapor environment 1

[Tariqi]

Hello,
If at the ambient temperature I pressurized a drum with 6 bar vapor ethane then I introduced a liquid propane to the drum, what will happen? will it prevent the propane from flashing (to avoid reaching CET) or will it flash faster with ethane in the system?

THANX.

 

[Latexman]

That depends, what is the ambient temperature?

Good luck,
Latexman

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[petrochemical87]

It will depend on the temperature. If you intend to store propane without allowing it to flash then you need to set the pressure taking into account the temperature of liquid propane.

 

[Tariqi]

Thanx all for replaying, the ambient temperature is approximately 23 degree centigrade; And I am intending of storing the liquid propane and vaporize it gradually but I don't want to reach the CET by introducing liquid propane to a none propane environment.

 

[Latexman]

CET?

When I eyeballed the propane vapor pressure curve, it looked like "ambient" had to be 9 C to not flash propane at 6 barg.

Good luck,
Latexman

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[petrochemical87]

Tariqi
I have no idea what CET means! A small amount of propane will flash till the pressure in your vessel reaches the saturation pressure of propane at 23 deg C, then no more flashing occurs.

 

[SNORGY]

CET = Critical Exposure Temperature (?) to me, but in the context of this thread it might mean something different.

 

[Tariqi]

CET means (critical exposure temperature) where the drum will fail at this temperature, in my case it is carbon steel so its CET is -29.

 

[cloa]

CET sounds like Critical Evaporative Temperature

 

[SNORGY]

In this context I believe cloa's definition.

 

[MortenA]

If you want the exact solution you may have to fire up that ol' PVT software pacakge - but you may also just assume that the partial pressure of the propane is equal the the vapour pressure at the given temperatures. If thats higher than 6 barg then the propane will "flash" - if theres enough propane (compared to your total volume= then you may ultimately reach the P_vap of propane. You may also be able to find a table of k values for propaane/ethane that will make it possible to calculate the final pressure (given that you know the volume, anount of propane and ethane.

Best regards, Morten

 

[sshep]

hey Tariqi,

The rule is to pressure up with vapor of the same composition for VLE reasons. I think ethane is possibly not much better than N2. You are going to get flashing and potentially < -29C until you get some propane vapor. How cold initially only depends on the efficiency of vapor diffusion away from the point of vaporization.

Concentrate on the point of addition. A small flow controlled at the propane source, good ambient heat input, a stainless section of pipe (or SS braided hose), and watch for ice. Cold (ice) shows the point of vaporization.

Best wishes,
sshep