Single mixed refrigerant lng production process
AssigneeAir Products and Chemicals, Inc.
InventorsMark Julian Roberts, Annemarie Ott Weist, Bo Jin, Brian James Barr
Life of this patent
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Abstract
A simple and efficient single mixed refrigerant process for cooling and liquefying a hydrocarbon feed stream, such as natural gas. The process employs a closed-loop single mixed refrigerant process for refrigeration duty. The refrigerant compressed to a high pressure using at least three stages of compression and two intercoolers (both producing liquid). A hydraulic turbine is used to expand the high pressure refrigerant before it flows into the main heat exchanger.
Claims21
A method for liquefying a hydrocarbon stream using a mixed refrigerant, the method comprising:
- (a) cooling and condensing the hydrocarbon stream and a cooled two-phase high pressure refrigerant stream in a main heat exchanger against an expanded refrigerant stream to form a liquefied hydrocarbon stream, a condensed refrigerant stream, and a vaporized refrigerant stream;
- (b) compressing the vaporized refrigerant stream in a first compression stage to a first pressure to form a low pressure compressed refrigerant stream;
- (c) cooling the low pressure compressed refrigerant in a first ambient cooler to form a cooled two-phase refrigerant stream;
- (d) separating the cooled two-phase refrigerant stream into a first cooled vapor stream and a first cooled liquid stream;
- (e) compressing the first cooled vapor stream in a second compression stage to a second pressure form a medium-pressure compressed stream;
- (f) pumping the first cooled liquid stream to the second pressure to form a pumped first cooled liquid stream;
- (g) combining the pumped first cooled liquid stream with the medium pressure refrigerant stream to form a combined medium-pressure refrigerant stream;
- (h) cooling the combined medium-pressure refrigerant stream in a second ambient cooler to form a cooled combined medium pressure refrigerant stream;
- (i) separating the cooled combined medium pressure refrigerant stream into a second cooled vapor stream and a second cooled liquid stream;
- (j) compressing the second cooled vapor stream in a third compression stage to a third pressure to form a high-pressure compressed stream;
- (k) pumping the second cooled liquid stream to the third pressure to form a pumped second cooled liquid stream;
- (l) combining the pumped second cooled liquid stream with the high-pressure compressed stream to form a two-phase high-pressure refrigerant stream;
- (m) cooling the two-phase high-pressure refrigerant stream in a third ambient cooler to form the cooled two-phase high-pressure refrigerant stream;
- and
- (n) expanding the condensed refrigerant stream through a hydraulic turbine to form the expanded refrigerant stream.
A method for liquefying a hydrocarbon stream using a mixed refrigerant, the method comprising:
- (a) cooling and condensing the hydrocarbon stream and a cooled two-phase high pressure refrigerant stream in a main heat exchanger against an expanded refrigerant stream to form a liquefied hydrocarbon stream, a condensed refrigerant stream, and a vaporized refrigerant stream;
- (b) compressing the vaporized refrigerant stream in a first compression stage to a first pressure to form a low pressure compressed refrigerant stream;
- (c) cooling the low pressure compressed refrigerant in a first ambient cooler to form a cooled two-phase refrigerant stream;
- (d) separating the cooled two-phase refrigerant stream into a first cooled vapor stream and a first cooled liquid stream;
- (e) compressing the first cooled vapor stream in a second compression stage to a second pressure form a high-pressure compressed stream having a pressure of at least 1000 PSIA (68.95 bara);
- (f) pumping the first cooled liquid stream to the second pressure to form a pumped first cooled liquid stream;
- (g) combining the pumped first cooled liquid stream with the high pressure refrigerant stream to form a combined high-pressure refrigerant stream;
- (h) cooling the combined high-pressure refrigerant stream in a second ambient cooler to form a cooled two phase high pressure refrigerant stream;
- and
- (i) expanding the condensed refrigerant stream through a hydraulic turbine to form the expanded refrigerant stream.
A method of designing and fabricating a system for liquefying natural gas using a closed loop single mixed refrigerant process that supplies refrigeration duty to a cryogenic heat exchanger having a plurality of coil wound bundles, each of the plurality of coil wound bundles having an overall tube length, the method comprising:
- (c) selecting a refrigeration duty for each of a plurality of coil wound bundles that minimizes differences in the overall tube length of each of the plurality of coil wound bundles;
- and
- (d) fabricating the system to provide the refrigeration duties selected in step (a);
- wherein the sole refrigeration duty for the cryogenic heat exchanger is a stream of the single mixed refrigerant that has been compressed to a pressure of at least 1000 PSIA (68.95 bara) and expanded by a hydraulic turbine.
Dependencies are inferred from the claim text.