Hi functionlake,

Your problem may be happened in LPG Plant for C3+ Splitter. When the Gas product is taken from the top and is cooled by the out let line of the discharge of Turbo expander then flashed in Cold Separator. The liquid from Separator will be fed to the top of C3+ Spliter. The operating temperature in Cold Sep is very low (-70 to 80 degree C)

I tried to calculate in HYSYS to know Nmin for your scenario but cannot find any method to apply for this case.

Is there anyone to help? Many thanks.