Method to produce natural gas liquids NGLs at gas Pressure Reduction Stations

A method to recover natural gas liquids (NGLs) at a pressure reduction station, comprising the steps of:

• providing at least one heat exchanger, a gas expander, a first separator, and a second separator at the pressure reduction station where gas from a main transmission gas line is reduced in pressure from between 400 to 900 PSIG (pounds per square inch gage) to from 50 to 95 PSIG for distribution through local distribution lines, each separator having a single inlet and only two outlets, namely, a first outlet and a second outlet, each heat exchanger having a flow path for passage of a high pressure natural gas stream and a counter current passage for a depressurised cold lean gas stream;
• removing water from the high pressure natural gas stream in order to prevent formation of hydrates by passing the high pressure natural gas stream, that has previously had a majority of the natural gas liquids removed during processing at a straddle plant, along the heat exchanger in order to cool the high pressure natural gas stream through a heat exchange with the depressurized cold lean gas stream before pressure reduction, and through the first separator such that water is condensed out of the high pressure natural gas stream and exits via the first outlet of the first separator;
• passing all of the remainder of the high pressure natural gas stream exiting via the second outlet of the first separator, which has had water removed, through the gas expander to reduce pressure of the natural gas stream to a reduced pressure of between 50 and 95 PSIG so it is suitable for consumption by a downstream user;
• passing the natural gas stream, which has been reduced in pressure to between 50 and 95 PSIG, through the second separator to produce a first stream of depressurized cold lean natural gas exiting through the first outlet of the second separator and a second stream of NGLs exiting through the second outlet of the second separator;
• and
• communicating the first stream exiting via the first outlet of the second separator at the reduced pressure of between 50 and 95 PSIG to the downstream user.