Flare Header

[txchemeit]

I am trying to estimate vacuum generated in flare due to thermal contraction in flare header due to temperature drop during global scenarios.

How should I estimate rate of condensation?

Thanks

 

[Chance17]

Two thoughts
1.) Use the ideal gas law based on volume of Flare header
2.) Any liquid seal at the Flare drum will operate in reverse to break vacuum (although this may inject air into the flare header.
This is the reason most Flare systems have positive gas injection (fuel gas) into the header.

 

[ChEMatt]

Estimate the rate of condensation by taking Yitbos suggestion and calculating the volume at the beginning temperature, and then again at the lowest expected temperature. Then simply plot the two temps and pressures and estimate a time for the temperature to decrease. That will give you a rate of pressure decrease that you can use to size your gas injection rate (which is what I'm assuming you are doing).

Onwards,

Matt