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[Nasiruddin]

Dear Friends,

I am working on a Simulation model, basically LPG recovery unit. Brief description is as follows:

"Feed Gas pass through series of gas-gas exchangers and chillers (Propane used as refrigerant) to cool down and then through JT expansion valves goes to Low tempertaure separator, from lean gas goes out from the system after excahanging heat with incoming feed gas stream. Liquids recovered from LTS sent to Deethainzer column and then LPG column for LPG purificatoin."

I modeled the above system and results were perfectly fine, with all temperature and pressures are within design limits.

In the second step above model is modified to add Lean Oil absorption column at the beginning. Now, feed gas first pass through the absorber column, where it comes into contact with cold Lean oil (Mol wt. 80) and then sent to its normal route. Rich lean oil from bottoms of aborption column send to deethanizer column. Lean oil is bascailly bottom of LPG column, part of this sent to storage and part of it cooled through chilled propane and used as lean oil.

Now the problem is with lean oil absorption column in operation, bottoms temperature of deethanizer are too high in the range of 350F, normally it should be around 240-250F, without lean oil circulation it was in the range of 230-240F.

Should anyone explain why the temperature of Deethanizer going too high with lean oil absorption.

Thanks and Regards,
Nasiruddin