2 replies to this topic

[coelhothiago]

To complete the mass balance I've to know a correlation that tells me which is the liquid volume of a certain gas volume of LGN(C3+) at an certain pressure and temperature. Like, 800 m3 of gas (C3+) will be ??? m3 of it liquefied at 30°C (86°F,303 K ), 100 psi (6 bar, 7kg/cm2, 069MPa) ? The compression volume? Researching at the Internet I've found that the correlation 600:1 of LGN(C3+), but this at normal conditions. Can I apply this correlation to my conditions or I'll have to do the analysis by real gas equations with compressibility factor?

Gas volume (800 m3) -----(refrigeration)-------> liquid volume (??? m3)

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[latexman]

I think you would need the gas density at T₁ and P₁ via PV = znRT or an equation of state. Calculate the mass = volume x density. Obtain the liquid density at 30^o C and 100 psig. Perry's Chemical Engineers' Handbook has sat'd properties of propane (and butane, if needed). Calculate the liquid volume = mass / density. I think the 600:1 ratio is a "rule of thumb" for LNG. If you need more accurate, best to use more rigorous techniques as described.

[shan]

Please understand that 600:1 means 600 (gas volume at the standard conditions): 1 (liquid volume process conditions). Here, the assumption is liquid volume does not vary with temperature and pressure. Not true but close enough.

Therefore, Gas Volume at process conditions: (800m3) -------Gas Volume at standard conditions: 800*(273/303)*(690/100) =4973.5 m3 ----------Liquid Volume:4973.5/600=8.3m3.