Method and apparatus for cooling a hydrocarbon stream

Patent metadata

Field	Value
Publication number	US-10704829-B2
Application number	US-201615006576-A
Country	US
Kind code	B2
Filing date	Jan 26, 2016
Priority date	Oct 11, 2006
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

A hydrocarbon stream, such as natural gas, is commonly cooled together with a first refrigerant stream, against an evaporating refrigerant in a series of one or more consecutively arranged common heat exchangers. The series comprises of one or more consecutively arranged common heat exchangers comprise a first common heat exchanger, upstream of which first common heat exchanger the hydrocarbon stream and the first refrigerant stream are not commonly cooled. The hydrocarbon stream to be cooled is fed into the first common heat exchanger at a hydrocarbon feeding temperature, while the first refrigerant stream is fed into the first common heat exchanger at a refrigerant feeding temperature. The temperature difference between the hydrocarbon feeding temperature and the refrigerant feeding temperature is lower than 60° C.

First claim

What is claimed is:

1. Method for cooling a hydrocarbon stream, wherein the hydrocarbon stream and a first refrigerant stream are commonly cooled against an evaporating refrigerant in a series of one or more consecutively arranged common heat exchangers, which series comprises a first common heat exchanger, upstream of which first common heat exchanger, the hydrocarbon stream, and the first refrigerant stream are not commonly cooled, the method at least comprising the steps of:
(a) compressing the first refrigerant stream comprising a first refrigerant to obtain a compressed first refrigerant stream;
(b) cooling the compressed first refrigerant stream against ambient to a refrigerant temperature;
(c) receiving the hydrocarbon stream to be cooled at a starting temperature that is lower than the refrigerant temperature;
(d) feeding the hydrocarbon stream into the first common heat exchanger at a hydrocarbon feeding temperature that is lower than the refrigerant temperature;
(e) further lowering the temperature of the first refrigerant stream, after said cooling of step (b), by heat exchanging against a medium different from ambient in a pre-cooling heat exchanger;
(f) feeding the first refrigerant stream into the first common heat exchanger, after said heat exchanging of step (e), at a refrigerant feeding temperature, wherein the refrigerant feeding temperature is lower than the refrigerant temperature, and wherein a temperature difference between the hydrocarbon feeding temperature and the refrigerant feeding temperature is lower than 60° C.;
(g) commonly cooling the hydrocarbon stream and the first refrigerant stream against an evaporating refrigerant in the series of one or more consecutively arranged common heat exchangers,
wherein said medium different from ambient comprises the hydrocarbon stream to be cooled upstream of said feeding of the hydrocarbon stream into the first common heat exchanger in step (d), and wherein a splitter splits the first refrigerant stream after the temperature of the first refrigerant stream has been further lowered by the pre-cooling heat exchanger in step (e) into a plurality of first refrigerant sub-streams each comprising a liquid.

2. Method according to claim 1 , wherein said temperature difference is lower than 5 C.

3. Method according to claim 2 , wherein the hydrocarbon feeding temperature and the refrigerant feeding temperature are substantially the same.

4. Method according to claim 1 , wherein said temperature difference is smaller than an initial temperature difference between said starting temperature and said refrigerant temperature.

5. Method according to claim 1 , comprising:
(h) removing the hydrocarbon stream from the series of one or more consecutively arranged common heat exchangers as a cooled hydrocarbon stream.

6. Method according to claim 5 comprising:
(i) further cooling the cooled hydrocarbon stream removed in step (h) in at least a second heat exchanger thereby obtaining a liquefied hydrocarbon stream.

7. Method according to claim 1 , further comprising feeding a second refrigerant into the first common heat exchanger.

8. Method according to claim 7 , wherein in addition to the first refrigerant stream and hydrocarbon stream, also the second refrigerant is commonly cooled in step (g).

9. Method according to claim 7 , wherein, before feeding the second refrigerant into the first common heat exchanger, the second refrigerant stream is compressed to obtain a compressed second refrigerant stream, cooled against ambient, and further cooled by heat exchanging against a medium different from ambient.

10. Method according to claim 1 , wherein said commonly cooling the hydrocarbon stream and the first refrigerant stream against an evaporating refrigerant comprises:
removing the first refrigerant from the first common heat exchanger;
expanding the first refrigerant to produce an expanded first refrigerant; and
returning the expanded first refrigerant to the first common heat exchanger while allowing the expanded first refrigerant to at least partially evaporate in the first common heat exchanger thereby withdrawing heat from the hydrocarbon stream and at least the first refrigerant stream.

11. Apparatus for cooling a hydrocarbon stream, the apparatus comprising:
a first refrigerant stream;
a compressor arranged to compress the first refrigerant stream to obtain a compressed first refrigerant stream;
an ambient cooler arranged to cool the compressed first refrigerant stream against ambient to a refrigerant temperature;
a pre-cooling heat exchanger arranged to receive the cooled compressed first refrigerant stream and to further lower the temperature of the first refrigerant stream by heat exchanging against a medium different from ambient;
a splitter coupled to the pre-cooling heat exchanger and configured to split the first refrigerant stream after the temperature of the first refrigerant stream has been further lowered by the pre-cooling heat exchanger into a plurality of first refrigerant sub-streams each comprising a liquid;
a hydrocarbon source arranged to provide the hydrocarbon stream to be cooled at a starting temperature that is lower than the refrigerant temperature;
a series of one or more consecutively arranged common heat exchangers arranged to receive and commonly cool at least the hydrocarbon stream and the first refrigerant stream, which series comprises a first common heat exchanger, such that upstream of which first common heat exchanger there is no other common heat exchanger wherein the hydrocarbon stream and the first refrigerant stream can be commonly cooled;
a hydrocarbon inlet on the first common heat exchanger arranged to receive the hydrocarbon stream at a hydrocarbon feeding temperature lower than the refrigerant temperature;
a first refrigerant inlet on the first common heat exchanger arranged to receive the first refrigerant from the pre-cooling heat exchanger at a refrigerant feeding temperature that is lower than the refrigerant temperature, and such that a temperature difference between the hydrocarbon feeding temperature and the refrigerant feeding temperature is lower than 60° C.,
wherein said medium different from ambient comprises the hydrocarbon stream to be cooled upstream of the first common heat exchanger.

12. Method according to claim 1 , wherein the first refrigerant stream is a multi-component refrigerant stream, and wherein the splitter splits the multi-component refrigerant stream into two streams having the same composition.

13. Method according to claim 1 , wherein the starting temperature of the hydrocarbon stream is lower than a temperature of said medium at an outlet of the pre-cooling heat exchanger as said medium is removed from the pre-cooling heat exchanger.

14. Method according to claim 13 , wherein the starting temperature of the hydrocarbon stream is lower than 10° C.

15. Method according to claim 1 , wherein the pre-cooling heat exchanger is a first pre-cooling heat exchanger, wherein the hydrocarbon feeding temperature of the hydrocarbon stream is generated by cooling the hydrocarbon stream by heat exchanging against a second medium that is evaporated in a second pre-cooling heat exchanger, and wherein a second pressure at which the second medium is evaporated in the second pre-cooling heat exchanger is higher than a first pressure at which said medium is evaporated in the first pre-cooling heat exchanger as part of the heat exchange in step (e).

16. Apparatus according to claim 11 , wherein the first refrigerant stream is a multi-component refrigerant stream.

Assignees

• Shell Oil Co

Inventors

• Kevenaar Mark Antonius
• Pek Johan Jan Barend
• Poh Chun Kit

Classifications

• F25J1/0214

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

• F25J1/0052

  by vaporising a liquid refrigerant stream · CPC title

• F25J2270/18

  External refrigeration with incorporated cascade loop · CPC title

• F25J1/0254

  controlling particular process parameter, e.g. pressure, temperature · CPC title

• F25J1/0292

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