Boil off gas pressure build-up

[Haru0202]

There is an insulated container of 100 m3 capacity which is 95% full with LNG (MM 16.4 kg/kmole) at -160 degC, saturated and at near ambient pressure (~0.2 barg). The heat ingress to the container develops 0.3 vol%/day of boil-off gas, resulting in the pressure inside the container to increase over time.

How do I calculate the pressure build-up after 1 day, 2 days, after x days, etc. before it reaches the PSV set point of 10 barg? Assume that no LNG is transfered out of / into the container during this time.

Thank you!

 

[LittleInch]

Student post / question?

For starters just use the ideal gas law, just remember to work in absolute pressure and absolute temperature. You can prob assume gass temp is close to -160. Volume of gas to vol of liquid use 600:1.

Let us know how it goes.

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[georgeverghese]

You can model this easily on the Depressure routine in Hysis or Simsci - Pro II.

 

[mpetier]

this heat & mass balance can be solved by hand calculation or in Excel...
For fluid properties look in tables (as suggested by LittleInch) or use some process library or maybe Nist database...

 

[LittleInch]

Yet another first time poster who vanishes into the ether.....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.