Patent ID: 8567213

Claim:
A processing plant for ethane recovery from a carbon dioxide-containing feed gas comprising: a control circuit that is operationally coupled to (1) a thermal sensor that is thermally coupled to a refluxed demethanizer and (2) a flow control element; an expander that is coupled to the refluxed demethanizer and a heat exchanger such that (a) the expander provides a first portion of an expander discharge stream to the heat exchanger to thereby form a heated expander discharge stream, (b) the expander provides a second portion of the expander discharge stream to the heated expander discharge stream to thereby form a temperature-controlled expander discharge, and (c) the temperature-controlled expander discharge is provided to the refluxed demethanizer; wherein the control circuit is configured such that the flow control element controls a flow ratio between the first and second portions of the expander discharge stream in response to a temperature sensed by the thermal sensor in the demethanizer such that the flow ratio is effective to increase a temperature in an upper section of the refluxed demethanizer while providing cooling to a portion of the carbon dioxide-containing feed gas; and wherein the heat exchanger is configured to form a subcooled stream from the portion of the carbon dioxide-containing feed gas for delivery to the demethanizer using refrigeration content of the first portion of an expander discharge.