Method of treating a hydrocarbon stream comprising methane, and an apparatus therefor

Patent metadata

Field	Value
Publication number	US-10215485-B2
Application number	US-201113807327-A
Country	US
Kind code	B2
Filing date	Jun 28, 2011
Priority date	Jun 30, 2010
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

In a method and apparatus for treating a hydrocarbon stream having methane, at least a part of the hydrocarbon stream and a main refrigerant stream are cooled by indirect heat exchanging against a pre-cooling refrigerant. The pre-cooled hydrocarbon stream is passed to a first inlet of an extraction column, and an effluent stream is discharged from the extraction column. The effluent stream and at least a part of the pre-cooled main refrigerant stream are passed to a further heat exchanger, where they are both cooled thereby providing a cooled methane-enriched hydrocarbon stream and at least one cooled main refrigerant stream. The passing of the effluent stream to the further heat exchanger and the passing of the pre-cooled hydrocarbon stream to the first inlet of the extraction column includes indirectly heat exchanging the effluent stream against the pre-cooled hydrocarbon stream.

First claim

What is claimed is:

1. Method of treating a hydrocarbon stream comprising methane, the method comprising:
cooling at least a part of the hydrocarbon stream and a main refrigerant stream by indirect heat exchanging against a pre-cooling refrigerant, to provide a pre-cooled hydrocarbon stream and a pre-cooled main refrigerant stream;
passing the pre-cooled hydrocarbon stream to a first inlet of an extraction column;
discharging an effluent stream, in the form of a methane-enriched hydrocarbon stream, from the extraction column via a vapour outlet arranged gravitationally higher relative to the first inlet into the extraction column, and a liquid methane-depleted hydrocarbon stream from the extraction column via a liquid outlet arranged gravitationally lower relative to the first inlet into the extraction column;
passing the effluent stream to a further heat exchanger;
passing at least a part of the pre-cooled main refrigerant stream to the further heat exchanger; and
cooling both the effluent stream and the at least part of the pre-cooled main refrigerant stream in the further heat exchanger thereby providing a cooled methane-enriched hydrocarbon stream and at least one cooled main refrigerant stream;

wherein said passing of the effluent stream to the further heat exchanger and said passing of the pre-cooled hydrocarbon stream to the first inlet of the extraction column comprises indirectly heat exchanging the effluent stream against the pre-cooled hydrocarbon stream,
wherein said indirectly heat exchanging of the effluent stream against the pre-cooled hydrocarbon stream comprises passing the pre-cooled hydrocarbon stream from a first inlet into an extraction column heat exchanger, through the extraction column heat exchanger in indirect heat exchanging interaction with the effluent stream, to a first outlet from the extraction column heat exchanger, and passing the effluent stream from a second inlet into the extraction column heat exchanger, through the extraction column heat exchanger in indirect heat exchanging interaction with the pre-cooled hydrocarbon stream, to a second outlet from the extraction column heat exchanger, further comprising extracting heat from at least one of:
the pre-cooled hydrocarbon stream between the first inlet into the extraction column heat exchanger and the first inlet of the extraction column;
the effluent stream between the vapour outlet from the extraction column and the second outlet from the extraction column heat exchanger;
vapour and/or liquid within the extraction column in an area being gravitationally minimally as high as the first inlet into the extraction column and maximally as high as the vapour outlet from the extraction column;

by heat exchanging against an auxiliary refrigerant stream.

2. The method according to claim 1 , wherein the auxiliary refrigerant stream comprises at least a part of the pre-cooled main refrigerant stream.

3. The method according to claim 1 , wherein said passing of the at least part of the pre-cooled main refrigerant stream to the further heat exchanger comprises separating the pre-cooled main refrigerant stream into a vaporous light fraction main refrigerant stream and a liquid second part pre-cooled main refrigerant stream; the method further comprising:
splitting the liquid second part pre-cooled main refrigerant stream into a continuing second part pre-cooled main refrigerant stream and a third part pre-cooled main refrigerant stream;
expanding the third part pre-cooled refrigerant stream thereby forming the auxiliary refrigerant stream.

4. The method according to claim 1 , further comprising adding heat to the extraction column at a location that is gravitationally lower than the first inlet.

5. The method according to claim 4 , further comprising splitting of the hydrocarbon stream into a first part hydrocarbon stream, which is subjected to said cooling by indirect heat exchanging against said pre-cooling refrigerant, said cooling being performed in a pre-cooling heat exchanger, and a second part hydrocarbon stream having the same composition and phase as the first part hydrocarbon stream; and wherein said adding of heat to the extraction column comprises passing the second part hydrocarbon stream to a second inlet of the extraction column being gravitationally lower than the first inlet of the extraction column, whereby the pre-cooling heat exchanger is bypassed.

6. The method according to claim 1 , further comprising admitting the effluent stream into the further heat exchanger via a first inlet and admitting the at least part of the pre-cooled main refrigerant stream into the further heat exchanger via least one second inlet, wherein the temperature of the effluent stream and the temperature of at least part of the pre-cooled main refrigerant stream in the first and second inlets in the further heat exchanger are less than 10° C. apart from each other.

7. The method according to claim 1 , wherein the hydrocarbon stream comprises natural gas, and wherein the cooled methane-enriched hydrocarbon stream is liquefied natural gas.

8. The method according to claim 1 , wherein the cooled methane-enriched hydrocarbon stream is depressurized and stored in a cryogenic liquid storage tank at a pressure of between 1 and 2 bar absolute.

Assignees

• Chantant Francois
• Meiring Wouter Jan
• Shell Oil Co

Inventors

• Chantant Francois
• Meiring Wouter Jan

Classifications

• F25J2270/18

  External refrigeration with incorporated cascade loop · CPC title

• F25J1/0292

  Refrigerant compression by cold or cryogenic suction of the refrigerant gas · CPC title

• F25J2270/66

  Closed external refrigeration cycle with multi component refrigerant [MCR], e.g. mixture of hydrocarbons · CPC title

• F25J1/0214

  as a dual level refrigeration cascade with at least one MCR cycle · CPC title

• F25J1/0239

  Purification or treatment step being integrated between two refrigeration cycles of a refrigeration cascade, i.e. first cycle providing feed gas cooling and second cycle providing overhead gas cooling · CPC title