2 replies to this topic

[paraschemix]

In one of my project, propylene is being pumped out of bullet and fed to process units. My Objective is to find the lowest operating pressure inside the propylene bullet.

 

Bullet volume : 3000 m3

Initial operating pressure of bullet: 21 barg

Min / Max ambient temperature : 4 / 46 C

Pump-out flow rate : 100 m3/h

 

I can directly calculate saturation pressure of propylene for Min / Max ambient temperature as 5.6 / 18 barg. But when propylene is emptied out of bullet (say from HLL to LLL), liquid propylene is flashed inside bullet to occupy vapor expansion? Due to flashing, temperature inside the bullet is reduced?

How to find out the lowest temperature reached in the bullet at LLL from HLL in the bullet for which I can calculate the propylene saturation pressure?

 

Note: no propylene vent equalization line & assuming no heat ingress. 

 

Thanks in advance!

 

Paranthaman 

[fallah]

Paranthaman,

 

IMO, pump out flow rate (100 m3/hr) is so low to be able to decrease the operating pressure/temperature due to flashing; but for worst case, say bullet depressurize to atmospheric pressure, you can consider this pressure as lowest pressure inside the tank. 

[Technical Bard]

This is a simple thermodynamic problem, if you assume adiabatic behaviour of the bullet.

Edited by Technical Bard, 21 January 2019 - 09:02 AM.