Patent ID: 9719024
Date: 2017-08-01
CPC Classifications: C10G,C10L,F25J,G05B,H04W

Claim:
1. A non-transitory digital storage medium storing executable program code for controlling a separation process of a raw natural gas stream into two controlled product streams comprising a methane stream and a natural gas liquids (NGLs) stream and a third uncontrolled ethane-rich stream, to control ethane content in the two controlled product streams, the program code executable by a hardware processor, the program code causing the hardware processor to execute steps comprising: monitoring a methane number of the methane stream to determine ethane content in the methane stream, wherein a higher methane number of the methane stream indicates a lower ethane content in the methane stream; monitoring a vapor pressure of the NGLs stream to determine ethane content in the NGLs stream, wherein a lower vapor pressure of the NGLs stream indicates a lower ethane content in the NGLs stream; receiving a desired minimum methane number (MMN) and a desired maximum vapor pressure (MVP); determining an inlet flow rate for the separation process, wherein the inlet flow rate is controllable by an inlet control valve; determining a system operating pressure for the separation process, wherein the system operating pressure is controllable by a pressure control valve; determining a temperature setpoint for the separation process, wherein the temperature setpoint is controllable by a temperature setpoint controller; and controlling the inlet flow rate by the inlet control valve, the system operating pressure by the pressure control valve, and the temperature setpoint by the temperature setpoint controller to maintain the desired minimum methane number (MMN) and the desired maximum vapor pressure (MVP) by separating ethane from the two controlled product streams into the third uncontrolled ethane-rich stream.