Cryogenic system for processing a hydrocarbon gas stream

A method for recovering a gas product stream and a liquid product stream from a hydrocarbon gas stream comprising:

• separating the hydrocarbon gas stream into a first liquid stream and an inlet vapor stream;
• cooling the inlet vapor stream in a first heat exchanger means to remove heat therefrom and to provide a cooled inlet vapor stream;
• cooling the cooled inlet vapor stream in a second heat exchanger means to lower the temperature of the cooled inlet vapor stream to a preselected processing temperature of at least about -50.degree. F.;
• separating the cooled inlet vapor stream into a first non-condensible vapor stream and a second liquid stream;
• passing the first non-condensible vapor stream through the first heat exchanger means in a heat exchange relationship with a first portion of the inlet vapor stream;
• means for recovering the first non-condensible vapor stream as a first portion of the gas product stream;
• separating the second liquid stream into an outlet vapor stream and a refrigerating fluid stream;
• passing the outlet vapor stream through the first heat exchanger means in a heat exchange relationship with a second portion of the inlet vapor stream;
• introducing the first liquid hydrocarbon stream and a portion of the refrigerating fluid stream into a stabilizer vessel and recovery therefrom a second non-condensible vapor stream and the liquid product stream;
• controlling the temperature of the second non-condensible vapor stream at a preselected process temperature in an upper portion of the stabilizer vessel;
• passing the second non-condensible vapor stream through the heat exchanger means wherein the second non-condensible vapor stream is combined with the outlet vapor stream in a heat exchange relationship with the second portion of the inlet vapor stream;
• recovering the second non-condensible vapor stream and the outlet vapor stream as a second portion of the gas product stream;
• passing the refrigerant stream through an expansion valve to reduce the pressure of the refrigerant stream to about 25 psig or less so as to effectively lower the temperature of the refrigerant stream to at least about -70.degree. F.;
• passing another portion of the refrigerating fluid stream sequentially through the second heat exchanger means and the first heat exchanger means in a heat exchange relationship with the cooled effluent vapor stream and a third portion of the inlet vapor stream, respectively;
• compressing the portion of the refrigerating fluid stream after passage through the first and second heat exchanger means to form a compressed refrigerating fluid stream;
• separating the compressed refrigerating fluid stream to provide a compressed vapor stream having an elevated temperature;
• passing the compressed vapor stream to a reboiler to provide heat for stabilizing and reboiling of the first liquid stream in the stabilizer vessel;
• recompressing the compressed vapor stream so as to form a compressed fluid stream and a compressed third liquid stream;
• passing the third liquid stream through an expansion valve to provide a cooled third liquid stream;
• passing the cooled third liquid stream through the second heat exchanger means to define a partially closed refrigeration loop;
• passing the compressed fluid stream through an expansion valve to reduce the pressure thereof to a pressure substantially corresponding to the pressure of the stabilizer vessel and into the stabilizer vessel.

A system for recovering a gas product stream and a liquid product stream from a hydrocarbon gas stream comprising:

• first separation means for separating the hydrocarbon gas stream into a first liquid stream and an inlet vapor stream;
• first heat exchanger means in fluid communication with the first separation means for cooling the inlet vapor stream;
• second heat exchanger means in fluid communication with the first heat exchanger means for cooling the cooled inlet vapor stream to a temperature of about -50.degree. F. or less;
• second separation means in fluid communication with the second heat exchanger means for separating the cooled inlet vapor stream into a first noncondensible vapor stream and a second liquid stream;
• first conduit means for passing the first non-condensible vapor stream through the first heat exchanger means so that the first non-condensible vapor stream is in a heat exchange relationship with a first portion of the inlet vapor stream;
• second conduit means for recovering the first non-condensible vapor stream as a first portion of the gas product stream;
• third separation means in fluid communication with the second separation means for separating the second liquid stream into an outlet vapor stream and a refrigerating fluid stream;
• third conduit means for passing the outlet vapor stream from the third separation means through the first heat exchanger means so that the outlet vapor stream is in a heat exchange relationship with a second portion of the inlet vapor stream;
• stabilizer means in fluid communication with the first and third separation means for receiving the first liquid stream and a portion of the refrigerating fluid stream so as to produce a second non-condensible vapor stream and the liquid product stream;
• means for controlling the temperature of the second non-condensible vapor stream at a preselected process temperature in an upper portion of the stabilizer means;
• fourth conduit means for passing the second non-condensible vapor stream through the first heat exchanger means so that the second non-condensible vapor stream is in a heat exchange relationship with a third portion of the inlet vapor stream wherein the stabilizer vapor is comingled with the vapor stream;
• means for recovering the second non-condensible vapor stream as a second portion of the gas product stream;
• fifth conduit means for passing the remaining portion of the refrigerating fluid stream sequentially through the second heat exchanger mean and the first heat exchanger means and the refrigerating fluid stream;
• means for reducing the pressure of the refrigerating fluid stream prior to passage through the second heat exchanger means to a pressure of about 25 psig or less so as to effectively lower the temperature of the refrigerating fluid stream to at least about -70.degree. F.;
• first compressor means operably connected to and in fluid communication with the first heat exchanger means for compressing the refrigerating stream to provide a heated vapor stream and for separating the refrigerating fluid stream into a compressed vapor stream, a fluid stream and a third liquid stream;
• reboiler means fluidly connected to the compressor means for defining a flow path for a heated vapor stream so that the heated vapor stream can be circulated between the compressor means and the reboiler means so as to provide heat for the reboiler means;
• means for reducing the pressure of the third liquid stream so as to substantially reduce the temperature of the third liquid stream;
• sixth conduit means for passing the cooled third liquid stream through the first heat exchanger means wherein the cooled third liquid stream is contacted with the refrigerating fluid stream in the first heat exchanger means in a heat exchange relationship with the first portion of the inlet vapor stream:
• and
• seventh conduit means for passing the fluid stream to the stabilizer means wherein the first liquid stream, the portion of the refrigerating fluid stream introduced into the stabilizer means and the fluid stream are stabilized.