Hello,
Recently we have observed pitting and erosion marks on the turbo-expander blades in one of our NGL recovery units and for that the turbo-expander manufacturer has claimed the possibility of presence of hydrocarbon liquids entering the turbo-expander. A sample at the inlet of the turbo-expander has been collected, analyzed and simulated using HYSYS to estimate the hydrocarbon dew point.Lab analysis is attached. The stream at the inlet of the turbo-expander is usually operating at a temperature of -54 C and a pressure of 49 barg. The hydrocarbon dew point was found to be -48 C at the same operating pressure. Is there a possibility of hydrocarbon liquids drop out at the stream entering the turbo-expander taking into consideration that the turbo-expander upstream separator is equipped with a demister located at the vapor outlet line. note that the vapor line from the turbo-expander separator to the inlet of the turbo-expander does not seem to slop towards the separator.
I have done the same evaluation based on the heat and material balance composition and conditions and I have found that there the temperature and hydrocarbon dew point are equal !
your views regarding this are appreciated.
Amine