Leung's method - LMTD query

[chemks2012]

Hello all,

I wish to calculate vent area required for two phase release by Leung’s method.
There is a term called ‘q’ with units W/kg i.e. total heat input per unit mass.

I wish to consider a release scenario and confused with LMTD.

Say reactor jacket is 95% full of water [at 20 degC] and locked in by closed outlet or drain valve and reactor mass at high temperature say 200 degC. Jacket has relief valve relieving temperature is 170 degC.
What would be the LMTD here?

Would that be….. LMTD = [(200-20)-(200-170)]/Ln[(200-20)/(200-170)] = ca. 83 degC

OR

Simply the difference between 200-170 = 30 degC?

Thanks in advance.

Regards, KS

 

[chemks2012]

Hello engineers,

Any input on this would be appreciated...

 

[met11]

I take it the relieving temperature is the corresponding saturation temperature of water for the relief valve set pressure + overpressure? If the jacket is at 170C, and the contents of the reactor are 200C everywhere, then the mean temperature difference is 30C (mean = log-mean in this case).

Why is the 20 included in your LMTD calculation? The jacket's either at 20 or 170 if the jacket has stopped flowing water.

 

[chemks2012]

Thanks met11
Agree[pre][/pre], 200-170 = 30deg C make more sense here.

Regards,
KS