Exergy destruction associated with maximising C2 recovery in an existing NGL facility

This study addresses increasing C2 recovery in an existing NGL plant through a set of operating conditions modifications targeting the decrease of the demethaniser temperature. The CO2 freezing problem associated with the reduction in temperature is first studied. Reducing the demethaniser pressure and temperatures of the low-temperature separator and reflux enabled to increase the C2 recovery from 59% to 94% with an increase in energy consumption by 16.5 MW. This however required the addition of a sweetening unit and a consequent additional increase in energy consumption by 31.8 MW. The exergy destruction and efficiency associated with revamp were also studied.