Pentane Pressure Rise
Pentane Pressure Rise
(OP)
Hi,
We transfer a liquid pentane at ambient temperature from the track to the storage tank(volume 50m3).
Since the storage tank is a pressure vessel, the filling procedure is executed without an atmospheric vent.
The question is:
1.Does pentane's filling will cause a pressure rise into the storage tank? (liquid volume increased, vapor volume decreased..)
2. Is it correct that part of pentane's vapor will be condensed due to pressure rising ?
The main assumption is that the tank's free volume contains only a pentane's vapor without non-condensable gases.
Thanks in advance
bmicky
We transfer a liquid pentane at ambient temperature from the track to the storage tank(volume 50m3).
Since the storage tank is a pressure vessel, the filling procedure is executed without an atmospheric vent.
The question is:
1.Does pentane's filling will cause a pressure rise into the storage tank? (liquid volume increased, vapor volume decreased..)
2. Is it correct that part of pentane's vapor will be condensed due to pressure rising ?
The main assumption is that the tank's free volume contains only a pentane's vapor without non-condensable gases.
Thanks in advance
bmicky





RE: Pentane Pressure Rise
The pressure will rise only if the ambient temperature rises - assuming, as you say, no non-condensables. Why should the vapor pressure rise if the temperature doesn't? The answer is that it doesn't rise - unless you've filled the system with 100% liquid pentane and no vapor space.
This is basic Smith & VanNess Thermo. and should be easily understood.
RE: Pentane Pressure Rise
Good luck,
Latexman
RE: Pentane Pressure Rise
Good comment and excellent tip Latex.
I treated the query strictly as it was presented - which is very close to being theoretical - and I agree with your pragmatic approach regarding the possibility of higher pressure (& possible pressure relief incidents) existing due to non-condensables. To avoid taking this into consideration is, in my opinion too simplistic. The existance of low boilers as dissolved impurities is yet another possibility. Designing or planning on the basis of pure vapor pressure is not being realistic.
RE: Pentane Pressure Rise
Good luck,
Latexman
RE: Pentane Pressure Rise
Now,I would like to change a scenario.
For example:
We transfer a liquid pentane at 100 F from the track to the storage tank(volume 50m3)by the pump with flow rate 15 m3/hr. The initial pentane's volume is 30 m3. The pressure in the vessel is 30 psia.
As far as I understand, the partial pressure of non-condensable will be 30 psia- 15.6 psia = 14.4 psia
Since the initial tank's free space is 20 m3, after 1 hr the free space will be 5 m3 (20 m3-15 m3).
The non-condensable's pressure rising (after 1 hr) will be:
14.4 psia * 20/5 = 57.6 psia.
Therefore, the total pressure in the tank after 1 hr will be 57.6 psia + 15.6 psia ( pentane's pressure at 100 F)=73.2 PSIA.
Is it correct?
Thanks in advance
bmicky
RE: Pentane Pressure Rise
Now were is the "heat removal" system needed to condense those C5 vapors, what about all the heat you put into the C5's through the pump. On small systems or ones realtively large changes. Think about the end where the pentanes come from, some pentanes must vaporize to fill the void, where is the energy coming from to make C5 vapors?
Just some thoughts for you to ponder, and trust me, they will bite you some day.