Cold-separator NGL recovery / dew-point control

A rich natural gas is chilled in the gas/gas exchanger + propane-chiller train (lumped here as one cold box) to -33 degC and let into a cold separator. The heavy hydrocarbons (C3+) drop out as a raw NGL liquid, leaving a leaner sales gas that meets its hydrocarbon dew-point spec — so no more liquid forms as the gas cools in the export pipeline. The cold separator is modelled as an adiabatic flash fed by the chiller, so the single knob (the chill temperature) drives both the NGL recovered and the refrigeration duty: colder recovers more NGL but costs more refrigeration (the built-in sensitivity). Peng-Robinson handles the hydrocarbon VLE; the companion gas-conditioning utilities (hydrate risk, water content, Joule-Thomson choke cooling, and compressor sizing for the sales-gas recompression) quantify the rest of the plant around it.