EA010564B1 - Process of low-temperature separation of gas components (embodiments) - Google Patents

Abstract

The present invention relates to a method of and apparatus for natural gas processing, namely, the process of low-temperature separation of gas components (LTS).

Description

Technical field

The present invention relates to a technique for gas separation, namely, to systems and methods for low-temperature gas separation.

The level of technology

Existing methods for low-temperature separation of the target components from the gas mixture are based on cooling the gas mixture, condensing the target components, followed by separation of the condensate containing the target components, and the gas mixture. While cooling the gas mixture is usually carried out either by performing mechanical work with the expansion of the gas in the nozzles or expanders, or with the use of cooling devices.

Typical processes of low-temperature separation of the target components from the gas mixture are described, for example, in patent documents I8 6182468 В1 and ВИ 2047061 С1. The method according to I8 6182468 B1 is based on cooling the gas mixture with its throttling in the Joule-Thomson valve, whereas according to KP 2047061 C1 a turbine of the expander is used.

The method described in I8 6182468 B1 includes cooling the mixture, expanding the mixture without performing mechanical work, partially condensing the mixture as it expands, separating the mixture or its part in a distillation column to produce products in the liquid and gas phases. In this case, the mixture is cooled by means of recuperative heat exchangers and a refrigeration unit, and the mixture is expanded by throttling the mixture in the Joule-Thomson valve.

The method described in KP 2047061 C1 includes cooling the mixture and separating it into vapor and liquid phases, expanding one part of the vapor phase without performing mechanical work, and the other with performing mechanical work, separating the expanded mixture in a distillation column to produce gas and liquid products .

Significant disadvantages of the described methods of low-temperature separation of gases are significant loss of pressure of the mixture in the process of low-temperature separation and increased energy costs.

Summary of Invention

In accordance with one aspect of an embodiment of the invention, the mixture is cooled, the mixture is expanded without performing mechanical work, partial condensation of the mixture during its expansion and separation of the mixture or its part in a distillation column to produce products in the liquid and gas phases. The process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the flow of the mixture is twisted, at the exit of the nozzle channel or its part the flow of the mixture is divided into at least two streams, one of which is enriched the heavier is methane, and the other is depleted of these components, the enriched stream is partially or completely sent to the distillation column, and the gas-phase products obtained in the distillation column are partially or completely sent to the mixture before its expansion .

In accordance with one aspect of an embodiment of the invention, there is provided a method for low-temperature separation of a gas mixture suitable for separating a mixture of hydrocarbon gases, comprising cooling the gas mixture; condensing the gas mixture to produce a stream of liquid and gas / vapor; rectification of at least a portion of the liquid stream to obtain corresponding gas-phase products; transfer of thermal energy to at least one of the streams of the first group, including the liquid stream, the gas / vapor stream and the gas-phase products stream from at least one other stream of the second group, including the gas mixture, the liquid stream, gas / vapor stream and the gas-phase products stream , or at least one of the streams of the first group to at least one other stream of the second group for energy reuse.

In some embodiments, the method also includes expanding and twisting at least a portion of the gas-phase products.

In some more specific embodiments, cooling the gas mixture includes at least partially mixing the gas mixture with at least a portion of at least one of the following streams: a liquid stream, a gas / vapor stream, a gas-phase product stream, another stream, the first and second streams.

In some more specific embodiments, cooling the gas mixture includes at least partial transfer of heat from the gas mixture to at least part of at least one of the following streams: liquid stream, gas / vapor stream, gas-phase product stream, another stream, first and second streams .

In some more specific embodiments, the method also includes compressing at least a portion of the gas-phase products.

In some more specific embodiments, the method also includes cooling at least a portion of the gas / vapor stream.

In some more specific embodiments, the method also includes compressing at least a portion of

- 1 010564 of the first thread.

In some more specific embodiments, the method also includes compressing at least a portion of the second stream.

In some more specific embodiments, the method also includes cooling at least a portion of the first stream.

In some more specific embodiments, the method also includes cooling at least a portion of the second stream.

In some more specific embodiments, the transfer of thermal energy includes mixing at least part of at least two streams between which heat transfer occurs.

In some more specific embodiments, the transfer of thermal energy involves the exchange of thermal energy between two streams without mixing these streams.

In some more specific embodiments, the method further comprises passing at least a portion of the gas / vapor stream through the turbine.

In some more specific embodiments, the method further comprises passing at least a portion of the second stream through the turbine.

In some more specific embodiments, the method further comprises condensing at least a portion of the gas-phase products.

In some more specific embodiments, the method further comprises condensing at least a portion of the liquid stream.

In some more specific embodiments, the method further comprises condensing at least a portion of the gas / vapor stream.

In some more specific embodiments, the method further includes expanding and twisting at least a portion of the gas-phase products.

In accordance with one aspect of an embodiment of the invention, there is provided a system for low-temperature separation of a gas mixture applicable to the separation of components of a mixture of hydrocarbon gases. This system contains the following devices:

a first gas-liquid separator for separating the source gas mixture into a liquid stream and a gas / vapor stream;

the first device for expanding the mixture, providing the first and second streams associated with the first gas-liquid separator to obtain a gas / vapor stream and containing spin means for spinning the gas / vapor stream and for separating, therefore, the heavy components of the gas / vapor stream from its lighter components, with the heavy components predominantly forming the first stream, and the lighter components preferentially forming the second stream;

a distillation column for obtaining at least gas-phase products, associated with a first gas-liquid separator for receiving a liquid stream, and at least one heat exchanger for transferring thermal energy to at least one of the first group streams including a liquid stream, a gas stream / vapor and gas-phase product stream from at least one other stream of the second group, including the gas mixture, liquid stream, gas / vapor stream and gas-phase product stream, or at least one of the first group streams Lower to one other flow of the second group for reuse of energy within the system.

In some embodiments, the first device for expanding the mixture is associated with a distillation column for supplying at least a portion of the first stream thereto.

In some more specific embodiments, the system further comprises a first mixer for mixing the source gas mixture with the return stream containing at least part of at least one of the following streams: liquid stream, gas / vapor stream, gas-phase product stream, another stream, first and second flows.

In some more specific embodiments, the system further comprises a first compressor for compressing at least a portion of the gas-phase products.

In some more specific embodiments, the system further comprises a first compressor for compressing at least a portion of the gas / vapor stream.

In some more specific embodiments, the system further comprises a first compressor for compressing at least a portion of the first stream.

In some more specific embodiments, the system further comprises a first compressor for compressing at least a portion of the second stream.

In some more specific embodiments, the system further comprises a first refrigeration unit for cooling at least a portion of the first stream.

In some more specific embodiments, the system further comprises a first refrigeration unit for cooling at least a portion of the second stream.

In some more specific embodiments, the transfer of thermal energy includes mixing at least part of at least two streams between which heat transfer occurs.

In some more specific embodiments, the transfer of thermal energy involves the exchange of thermal energy between two streams without mixing these streams.

- 2 010564

In some more specific embodiments, the system further comprises a turbine for expanding at least a portion of the gas / vapor stream associated with the first gas-liquid separator to obtain at least a portion of the gas / vapor stream from it.

In some more specific embodiments, the system further comprises a turbine, which is installed with the possibility of receiving at least part of the second stream and through which at least part of the second stream passes.

In some more specific embodiments, the system further comprises at least another gas-liquid separator for separating at least a liquid stream or a gas / vapor stream inside the system.

In some more specific embodiments, the system further comprises at least one more condenser to further condense at least a portion of the fluid flow.

In some more specific embodiments, the system further comprises at least one other condenser for condensing at least a portion of the gas / vapor stream.

In some more specific embodiments, the system further comprises another device for expanding and twisting at least part of the gas-phase products.

In this case, variants of the method according to the invention are recommended for use when the enriched stream is sent partially or completely into a distillation column, and gas-phase products leaving the distillation column are mixed partially or completely with a lean stream; the enriched stream is sent partially or completely into the mixture before its expansion, and gas-phase products coming from the distillation column are mixed partially or completely with the lean stream or the enriched stream and gas-phase products leaving the distillation column are sent partially or fully into the mixture before its expansion.

Other aspects and features of the present invention will become apparent to those skilled in the art upon consideration of the following description of specific embodiments of the invention.

Short list of drawings

To facilitate an understanding of the present invention and in order to more clearly show how it can be implemented, the following will refer to the accompanying drawings, which illustrate various aspects of embodiments of the present invention as an example. In the drawings:

FIG. 1 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a first embodiment of the invention;

FIG. 2 is a schematic depiction of the apparatus for low-temperature separation of gases shown in FIG. one;

FIG. 3 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a second embodiment of the invention;

FIG. 4 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a third embodiment of the invention;

FIG. 5 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a fourth embodiment of the invention;

FIG. 6 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a fifth embodiment of the invention;

FIG. 7 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a sixth embodiment of the invention;

FIG. 8 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a seventh embodiment of the invention;

FIG. 9 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with an eighth embodiment of the invention;

FIG. 10 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a ninth embodiment of the invention;

FIG. 11 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a tenth embodiment of the invention;

FIG. 12 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with an eleventh embodiment of the invention;

FIG. 13 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a twelfth embodiment of the invention;

FIG. 14 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a thirteenth embodiment of the invention;

FIG. 15 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a fourteenth embodiment of the invention;

FIG. 16 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a fifteenth embodiment of the invention;

FIG. 17 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a sixteenth embodiment of the invention;

- 3 010564 FIG. 18 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a seventeenth embodiment of the invention;

FIG. 19 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with an eighteenth embodiment of the invention;

FIG. 20 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a nineteenth embodiment of the invention;

FIG. 21 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a twentieth embodiment of the invention;

FIG. 22 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with the twenty-first embodiment of the invention;

FIG. 23 is a schematic depiction of a system for low-temperature separation of a gas mixture in accordance with a twenty-second embodiment of the invention.

Information confirming the possibility of carrying out the invention

Some of the variants of the invention allow to reduce energy costs in low-temperature separation plants (STC). This task according to some variants of the invention, including the first version of the proposed method, can be solved due to the fact that according to this method, which includes, like the well-known STC process for a mixture of hydrocarbon gases, cooling the mixture, expanding the mixture or its part without performing mechanical work, partial condensation of the mixture during its expansion, separation of the mixture or its part in a distillation column to obtain products in the liquid and gas phases, the process of expansion of the mixture is carried out by passing the mixture through the nozzle to The mixture flow is twisted in the nozzle channel and / or at the inlet to the nozzle channel; the enriched stream is partially or completely sent to the distillation column, and gas-phase products obtained in the distillation column are partially or completely sent to the mixture before its expansion.

FIG. 1 is a schematic depiction of a system 200 for low-temperature separation of a gas mixture (hereinafter referred to as system 200 for brevity) in accordance with the first embodiment of the invention. Specialists in the relevant field will understand that system 200 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of system 200. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The system 200 comprises a series-connected first mixer 30, a first heat exchanger 32, a first refrigeration unit 34 and a gas-liquid separator 36. In some embodiments, a heat exchanger may be used as a refrigeration unit. The first mixer 30 has first and second inputs 30a, 30b, respectively. The first input 30a is the input not only for the first mixer, but also the input to the system 200 as a whole. The second input 30b serves as an input for the return stream, the purpose of which will be described in more detail below. The gas-liquid separator 36 has the first and second outputs 36a, 36b, respectively. The first outlet 36a is the gas / vapor outlet, and the second outlet 36b is the outlet for the liquid (or for the mixed phase). In some embodiments, the gas-liquid separator 36 is a condenser.

The system also contains a device 40 for expanding the mixture and a distillation column 38. The device 40 for expanding the mixture is connected to receive a gas / vapor flow to the first outlet 36a of the gas-liquid separator 36, while the second outlet 36B of the gas-liquid separator 36 is connected to the distillation column 38 to feed a stream of liquid (or mixed phase) into it.

The device 40 for expanding the mixture has the first and second outputs 40a and 40b, respectively. The first outlet 40a is connected to a distillation column for feeding a first stream into it, preferably containing heavier components. The second outlet 40b is connected along the return line to the inlet of the first heat exchanger 32 in order to cool the gas mixture entering the first mixer 30.

Distillation column 38 has the first and second outputs 38a and 38b, respectively. The first outlet 38a through the return line is connected to the second inlet 30b of the first mixer 30. The system 200 also includes a compressor 42 and a second refrigeration unit 44 connected in series between the first outlet 38a of the distillation column and the second inlet 30b of the mixer 30.

Before describing the operation of the system 200, it will be described in more detail with reference to FIG. 2, an apparatus 40 for expanding the mixture is described. The device 40 for expanding the mixture has a tubular body with inlet and outlet ends, designated as A and B, respectively. The device 40 for expanding the mixture further comprises a device 41 for swirling the flow, located near the input end of the device 40, and a converging-expanding nozzle channel 43, located behind the device 41 for spinning the flow. In some embodiments, the device 41 for spin flow may contain at least one blade. The tapering-expanding nozzle channel 43, expanding, passes into a conical section 45, which ends with an output end B. At the output end B, inside the conical

- 4 010564 section 45, located divider 47, which promotes the separation of output streams directed to the first and second outputs 40a, 40b, respectively.

The device 40 for expanding the mixture can be performed with the installation of the device 41 for swirling the flow as at the entrance to the nozzle channel, as shown in FIG. 2 (i.e., as proposed in patent publications EP 1301588, I8 6372019), as well as inside the nozzle channel (i.e., as proposed in patent publications EP 0496128, UO 99/01794).

The system 200 shown in FIG. 1 and 2, works as follows. The incoming stream 201 of a mixture corresponding to natural gas or another gas mixture enters the system 200 through the mixer 30, where it is mixed with the stream returned from the distillation column 38 and containing compressed and cooled gas-phase products. The combination of incoming natural gas and recovered products is further cooled in the first heat exchanger 32. In accordance with the general feature of the invention, the first heat exchanger 32 facilitates the recovery of thermal energy, which in this embodiment corresponds to the reuse of energy used to cool various streams within the system. More specifically, the first heat exchanger 32 cools the incoming gas mixture in the form of natural gas by transferring heat from the mixture in the form of natural gas to the flow returned from the second outlet 40b of the device 40 to expand the mixture, resulting in cooling of the mixture in the form of natural gas.

The mixture in the form of natural gas before supplying it to the gas-liquid separator 36 is further cooled in the first refrigeration unit 34. Inside the gas-liquid separator 36, the mixture in the form of natural gas is divided into a gas / vapor stream and into a stream containing a liquid (or mixed) phase . The gas / vapor stream flows from the gas-liquid separator 36 through its first outlet 36a directly to the device 40 for expanding the mixture. The liquid flow enters from the gas-liquid separator 36 through its second outlet 36b directly into the distillation column 38.

At the first outlet 38a of the distillation column, gas-phase products are obtained, and at its second outlet 38b liquid products are obtained. Gas-phase products are compressed in compressor 42 and cooled in a second refrigeration unit 44 before mixing them with said incoming (initial) mixture 201.

As shown in FIG. 2, inside the device 40 for expanding the mixture, the incoming gas / vapor stream is divided into first and second streams. The mixture based on natural gas enters the device 40 to expand the mixture, is twisted using the device 41 to spin the flow and expands, passing through the tapering-expanding nozzle channel 43. In the process of expanding the flow of the mixture, the heavier components of the mixture move from the central axis, while as lighter components remain near the central axis. That is why the flow of the gas mixture is divided at least into the first and second streams in such a way that the first stream contains mostly heavier components, and the second stream contains mostly lighter components. The first stream exits the device 40 to expand the mixture through its first outlet 40a. The second stream exits the device 40 to expand the mixture through its second outlet 40b.

More specifically, in some of the system variants, the gas / vapor flow temperature during the expansion process is sufficiently lowered to cause a partial condensation of the mixture, i.e. the formation of condensate. Drops of condensate in the field of centrifugal forces move to the walls of the device 40 to expand the mixture, forming a two-phase flow near the walls. When the gas mixture is natural gas, the first stream contains components heavier than methane, while the second stream has a significantly higher methane content.

Since in the expansion process, when the mixture is spun in the device 40 for expanding the mixture, the static pressure of the mixture is lower than the pressure at the outlets from the device 40 for expanding the mixture, separation of the mixture inside the nozzle channel occurs at lower temperatures than the temperature of the mixture as it passes through the specified outlets. However, in some embodiments, by returning the gas-phase product from the distillation column 38 to the incoming mixture 201 before it is processed, a deeper separation of the mixture is provided.

After separation of the flows in the device 40 to expand the mixture, at least one of them can be compressed by passing the flow through the diffuser. FIG. 2 shows an example when in the device for expanding the mixture at the outlet of the nozzle channel the flow of the mixture is divided into two streams, each of which is then compressed in a diffuser. This allows you to reduce the pressure loss on the device 40 to expand the mixture.

Before expansion, the mixture or its part can be mixed in the ejector with gas-phase products coming from the distillation column. An example of such an implementation is illustrated in FIG. 1, in which an ejector is used as a mixer 30.

In the next version of the proposed method of low-temperature separation of a mixture of hydrocarbon gases, including cooling the mixture; expansion of the mixture or its parts without performing mechanical work; partial condensation of the mixture during its expansion; separation of the mixture or its part in the distillation column to obtain products in the liquid and gas phases, the process of expansion of the mixture is carried out, in accordance with the invention, passing the mixture through the nozzle channel. At the same time in the nozzle

- 5 010564 channel and / or at the entrance to the nozzle channel the flow of the mixture is twisted, at the exit of the nozzle channel or its part the flow of the mixture is divided into at least two streams, one of which is enriched in components heavier than methane and the other is depleted in these components. The enriched stream is partially or fully sent to the distillation column, and gas-phase products coming from the distillation column are partially or completely mixed with the lean stream.

FIG. 3, a schematic representation of a system 300 for low-temperature separation of a gas mixture (hereinafter referred to as system 300 for brevity) is given in accordance with a second embodiment of the invention. The system 300 shown in FIG. 3 is similar to the system 200 illustrated in FIG. 1, so that elements common to both systems have the same numerical designation. Moreover, when considering FIG. 3 parts of the description, similar to parts of the description of FIG. 1, for brevity will be omitted. Those skilled in the art will recognize that system 300 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software used to make the system 300 work. However, the drawing shows only those elements that are necessary to describe various aspects. this option.

The differences between systems 200 and 300 are as follows. The system 300 does not contain the first mixer 30, the first refrigeration unit 34, the second refrigeration unit 44 and the first compressor 42, but contains the second mixer 48 and the first (throttle) valve 50. The first throttle valve is connected between the second outlet 36b of the gas-liquid separator 36 and distillation column 38. The second mixer 48 has first and second outlets, which are designed to accept and mix gas / vapor streams coming from the device 40 for expanding the mixture and the distillation column 38. The second mixer also has an outlet d, from which the gas mixture can flow to the first heat exchanger 32.

When the system is running, the initial mixture 301 is cooled in the first heat exchanger 32 before being fed directly to the separator 36. Liquid flow from the separator 36 is directed through the throttle valve 50 to the distillation column 38. The gas-phase products from the distillation column are mixed in the second mixer 48 with the second stream (containing mainly lighter separation components) from the mixture expansion device 40 to obtain a mixed flow for the return line. This stream then passes through the first heat exchanger 32, in which heat is transferred from the initial mixture 301 to the stream entering the return line, resulting in cooling of the initial mixture without adding energy to the system 300.

This method allows to reduce the required pressure drops in installations for low-temperature separation.

In another embodiment of the proposed method of low-temperature separation of a mixture of hydrocarbon gases, including cooling the mixture; expansion of the mixture or its parts without performing mechanical work; partial condensation of the mixture during its expansion; the separation of the mixture or its part in the distillation column to obtain products in the liquid and gas phases, in accordance with the invention, the expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the flow of the mixture is twisted, at the exit From the nozzle channel or its part, the mixture flow is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components. The enriched stream is partially or completely sent to the mixture before its expansion, and the gas-phase products coming from the distillation column are partially or completely mixed with the depleted stream.

FIG. 4 shows a schematic depiction of a system 400 for low-temperature separation of a gas mixture (hereinafter referred to as system 400 for brevity) in accordance with a third embodiment of the invention. The system 400 shown in FIG. 4 is similar to the systems illustrated in FIG. 1 and 3, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 4 parts of the description, similar to parts of the description of FIG. 1 and 3 will be omitted for brevity. Specialists in the relevant field will understand that system 400 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 400. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant shown in FIG. 4, has the following features. The system 400 comprises a first mixer 30, similar to that shown in FIG. 1. System 400 also includes a second refrigeration unit 44 and a first compressor 42. However, the first compressor 42 and the second refrigeration unit 44 are connected between the first heat exchanger 32 and the second inlet 30b (connected to the return line) of the first mixer 30. The first outlet 40a of the device 40 to expand the mixture, it is connected to the first heat exchanger 32, and not to the distillation column 38, as shown in FIG. one.

During operation of the system, the initial mixture 401 is mixed in the first mixer 30 with the first stream (i.e. with a stream containing mostly heavier components of the mixture separated in the device 40 for expanding the mixture). Thus, the first stream from the first output 40a of the device 40 to expand

- 6 010564 rhenium mixture is mixed with the original mixture 401. The mixture leaving the first mixer 30 is then passed through the first heat exchanger 32, to further adjust the temperature of the gas mixture flowing into it. The first heat exchanger 32 is configured to supply, as a stream for temperature control, the flow from the first outlet of the device 40 to expand the mixture. Thanks to the use of the return line, energy is again saved in the system, due to which its efficiency can be increased.

In some embodiments, the gas-phase products flowing out from the distillation column 38 are mixed with the second stream coming from the second outlet 40B of the device 40 for expanding the mixture in the second mixer 48, and the resulting mixture cannot be released from the system 400.

In one embodiment of the method of low-temperature separation of a mixture of hydrocarbon gases, including cooling the mixture; expansion of the mixture or its parts without performing mechanical work; partial condensation of the mixture during its expansion; The separation of the mixture or its part in the distillation column to obtain products in the liquid and gas phases, according to the invention, the process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and the mixture flow is twisted in the nozzle channel and at the exit of the nozzle channel channel or part of it, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components, the enriched stream and gas-phase products coming from distillation column, partially or completely directed to the mixture before its expansion.

FIG. 5 shows a schematic depiction of a system 500 for low-temperature separation of a gas mixture (hereinafter referred to as system 500 for brevity) in accordance with a fourth embodiment of the invention. The system 500 shown in FIG. 5 is similar to the systems illustrated in FIG. 1 and 3, 4, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 5 parts of the description, similar to parts of the description of FIG. 1 and 3, 4, for brevity will be omitted. Specialists in the relevant field will understand that system 500 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 500. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant shown in FIG. 5, has the following features. The system 500 comprises a second heat exchanger 52. The second mixer 48 and the second heat exchanger 52 are connected between the first outlet 36a of the gas-liquid separator 36 and the inlet of the device 40 for expanding the mixture. The second heat exchanger 52 is also configured to receive the first stream from the first outlet 40a of the device 40 for expanding the mixture before this first stream goes to the first heat exchanger 32, as described with reference to FIG. four.

When the system is operating, the steam flow from the separator 36 is mixed with the gas / vapor stream coming from the outlet of the distillation column 38 in the second mixer 48. The stream coming from the second mixer 48 is cooled in the second heat exchanger 52 before passing through the device 40 to expand the mixture. the stream (from the first outlet 40a of the device 40 for expanding the mixture) is first passed through the second heat exchanger 52 (in order to cool the stream from the outlet of the second mixer 48), and then through the first heat exchanger 32 (in order to cool the stream from the exit the first mixer 30). After that, the same first stream is compressed in the first compressor 42, and then cooled in the second refrigeration unit 44 before mixing it with the original gas mixture 501. The second stream (from the second outlet 40b of the mixture expansion unit 40) can be served directly to the output of the system 500. Through the use of the return line, energy is again saved in the system, due to which its efficiency can be improved.

Some embodiments of system 500 facilitate deep cleaning of the second exit stream from device 40 to expand the mixture (i.e., a stream containing mostly lighter components of the gas mixture). More specifically, in relation to the processing of natural gas by mixing the first stream with the initial mixture 501, the second stream can be significantly depleted in terms of vapor components heavier than methane.

Before the expansion process and / or after it, the liquid phase can be separated from the mixture or its part, which is passed through the throttle valve, and the resulting products are sent to a distillation column. FIG. 6, as an example, is given a schematic depiction of a system 600 for low-temperature separation of a gas mixture (hereinafter referred to as system 600 for brevity) in accordance with a fifth embodiment of the invention. The system 600 shown in FIG. 6 is similar to the systems illustrated in FIG. 1 and 3-5, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 6 parts of the description, similar to parts of the description of FIG. 1 and 3-5, for brevity will be omitted. Specialists in the relevant field will understand that system 600 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of system 600. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

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The variant shown in FIG. 6, has the following features. The system 600 comprises a second gas-liquid separator 60, which has first and second outlets 60a and 60b, respectively, associated with a second mixer 48 and with a distillation column 38. System 600 also contains a second (throttle) valve 66 connected between the second outlet 60b and the entrance of the distillation column 38. The first output 40a of the device 40 for expanding the mixture is made with the possibility of feeding the first stream from the device 40 for expanding the mixture to the second separator 60 gas-liquid.

During the operation of the system, since it has two gas-liquid separators 36, 60, the liquid is separated twice: before and after the expansion of various forms of the mixture in the device 40 to expand the mixture. More specifically, the first stream from the mixture expansion device 40 is fed to the second gas-liquid separator 60, which forms the second vapor phase stream and the second liquid stream. The second liquid stream passes through the second throttle valve 66 and enters the distillation column 38. The second vapor phase stream is mixed with the second stream from the device 40 to expand the mixture in the second mixer 48. The mixture obtained in the second mixer 48 is passed through the first heat exchanger 32, as it has been described before.

In all the described embodiments of the method, the gas-phase product coming from the distillation column can be further cooled. FIG. 7, as an example, is given a schematic depiction of a system 700 for low-temperature separation of a gas mixture (hereinafter referred to as system 700 for brevity) in accordance with the sixth embodiment of the invention. System 700 shown in FIG. 7 is similar to the systems illustrated in FIG. 1 and 3-6, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 7 parts of the description, similar to parts of the description of FIG. 1 and 3-6 for brevity will be omitted. Specialists in the relevant field will understand that system 700 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 700. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 700, has the following features. The second heat exchanger 52 is connected between the first choke valve 50 and the inlet of the distillation column 38. The second refrigeration unit 44 is connected between the distillation column 38 and the second heat exchanger 52. More specifically, the second refrigeration unit 44 is installed with the possibility of receiving and cooling gas-phase products from the first output 38a distillation column 38. The second heat exchanger 52 is also connected to the first mixer 30 in order to supply cooled gas-phase products from the distillation column 38 as a return by thallium input to first mixer 30.

During operation of the system, the initial mixture 701 is mixed with gas-phase products coming from the distillation column 38, as shown in FIG. 1. However, first, before mixing with the initial mixture, the gas-phase products are cooled by the second refrigeration unit 44 and the second heat exchanger 52. At the same time, the second heat exchanger 52 heats the second stream from the separator 36 gas-liquid before it is fed to the distillation column 38. This implementation contributes to a more rational distribution mass flow and enthalpy in the process of low-temperature separation.

In some embodiments of the method, at least part of the gas-phase product coming from the distillation column is sent to the mixture prior to its expansion together with part of the products obtained by passing the liquid separated from the mixture through the throttle valve. FIG. 8, as an example, is given a schematic depiction of a system 800 for low-temperature separation of a gas mixture (hereinafter referred to as system 800 for short) in accordance with a seventh embodiment of the invention. System 800, shown in FIG. 8 is similar to the systems illustrated in FIG. 1 and 3-7, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 8 parts of the description, similar to parts of the description of FIG. 1 and 3-7, for brevity, will be omitted. Specialists in the relevant field will understand that system 800 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 800. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 800, has the following features. The separation of the liquid from the mixture is performed twice before expansion in the device 40 to expand the mixture. To this end, the second gas-liquid separator 60 is turned on so as to receive a combination of a liquid flow (or a two-phase flow) from the first gas-liquid separator 36 and gas-phase products from the rectification column 38. At the same time, the gas-phase products from the rectification column 38 are first passed through the second heat exchanger 52, which also receives the liquid phase (or two-phase flow) from the output of the second separator 60. This makes it possible to transfer thermal energy between the two named flows with appropriate cooling from one flow and heating of another in order to reuse the energy within the system 800.

The original mixture 801 before serving in the first separator 36 gas-liquid is cooled in the first heat

- 8 010564 of the exchanger 32 and is additionally cooled in the first refrigerating unit 34. The liquid-gas flow from the separator 36 is passed through the throttle valve 50 and mixed with the gas-phase products coming from the distillation column 38 before being fed to the second separator 60. 60 gas-liquid forms a second fluid flow, which is passed through the second heat exchanger 52, as a result of which the gas-phase products are cooled and the second fluid flow is heated. After passing through the second heat exchanger 52, the second liquid stream enters the distillation column 38. The system also provides for combining the gas / vapor flows from the first and second separators 36, 60 in the second mixer 48 before they are fed into the device 40 to expand the mixture, within which, with respect to the mixture, the process described above with reference to FIG. 1 and 2 and leading to the formation of the first and second streams. With regard to the processing of natural gas, this method allows to achieve a deeper cleaning of the gas stream by removing a larger proportion of the components heavier than methane.

In some embodiments, part of the liquid separated from the mixture is passed through a throttle valve, and the resulting products are used to further cool the mixture, pumping them through the heated channels of the heat exchanger, in which the mixture is cooled. Further, these products are sent to the mixture before its expansion. FIG. 9, by way of example, is given a schematic depiction of a system 900 for low-temperature separation of a gas mixture (hereinafter referred to as system 900 for brevity) in accordance with an eighth embodiment of the invention. System 900, shown in FIG. 9 is similar to the systems illustrated in FIG. 1 and 3-8, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 9 parts of the description, similar to parts of the description of FIG. 1 and 3-8, for brevity, will be omitted. Specialists in the relevant field will understand that system 900 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of system 900. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 900, has the following features. The first refrigeration unit 34 is installed in front of the first heat exchanger 32. The third heat exchanger 62 is connected in series between the first heat exchanger 32 and the first gas-liquid separator 36. The third heat exchanger 62 is also configured to receive a portion of the liquid (or two-phase) flow from the first gas-liquid separator 36. Therefore, a second throttle valve 66 is turned on between the second outlet 36b of the first separator and the third heat exchanger 62 in order to prevent flow reversal and to maintain the pressure pressure through the third heat exchanger 62. In addition, as in the system 500 shown in FIG. 5, the gas-phase products from the outlet of the distillation column 38 are combined with the gas / vapor stream from the first gas-liquid separator 36 before expansion in the mixer 48. For this purpose, in the same way as shown in FIG. 8, the second heat exchanger 52 is connected between the first outlet 38a of the distillation column 38 and the second mixer 48. The second heat exchanger 52 also receives a portion of the fluid flow from the first gas-liquid separator 36, with the first throttle valve 50 included between them.

When the system is operating, a portion of the fluid flow from the first gas-liquid separator 36 is used to cool the initial mixture 901. The initial mixture 901 is also cooled in the first refrigeration unit 34, and then mixed with a portion of the liquid stream from the first gas-liquid separator 36, as it will be described in detail below. The resultant mixture is further cooled in the first heat exchanger 32 and in the third heat exchanger 62 before feeding it to the first gas-liquid separator 36. As should be clear from the previous description, the first gas-liquid separator 36 forms a gas / vapor flow and a liquid flow (two-phase flow). The gas / vapor stream is mixed in a second mixer 48 with gas phase products from distillation column 38, and the resulting gas / vapor mixture is expanded and divided into first and second streams, as described above with reference to FIG. 1 and 2. The first stream is fed to the distillation column 38, and the second stream is returned to the first heat exchanger 32. As in the previously described systems, the heat exchangers promote energy reuse within the system 900, thereby increasing its efficiency.

In some embodiments, a turboexpander may be used before or after expansion of the mixture. FIG. 10, as an example, is given a schematic depiction of a system 1000 for low-temperature separation of a gas mixture (hereinafter referred to as system 1000 for short) in accordance with a ninth embodiment of the invention. The system 1000 shown in FIG. 10 is similar to the systems illustrated in FIG. 1 and 3-9, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 10 parts of the description, similar to parts of the description of FIG. 1 and 3-9, for brevity will be omitted. Specialists in the relevant field will understand that system 1000 also contains the appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1000. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to the system 1000 has the following features. System 1000 with

- 9 010564 holds a turbine 70 installed between the second output 40b of the device 40 for expanding the mixture and the first heat exchanger 32. The system 1000 also contains a second compressor 64 connected in series between the first compressor 42 and the second input 30b of the first mixer 30.

When the system is operating, the second stream coming from the second outlet 40B of the device 40 to expand the mixture is passed through the turbine 70 and then through the first heat exchanger 32. In some embodiments, a turbine or similar device such as a turboexpander to expand the mixture can be used to provide additional expansion before or after the mixture passes through the device 40 to expand the mixture. In addition, the original mixture 1001 is mixed with a return gas / vapor stream, which includes portions of the liquid stream from the second separator 60 gas fluid. After that, the resulting mixture is cooled in the first heat exchanger 32 until it enters the first gas-liquid separator 36.

The fluid flow from the first separator 36 gas-liquid is divided into first and second parts. The first part is passed through the throttle valve 50 and fed to the distillation column 38. The second part of the first liquid flow before mixing it with the gas / vapor flow from the second gas-liquid separator 60, is passed through the second throttle valve 66. In contrast, the flow gas / vapor from the first separator 36 gas-liquid is passed through the second heat exchanger 52, where it is cooled before entering the second mixer 48. The second mixer also receives gas-phase products from the distillation column 38. The output of the second mixer , as described earlier, is associated with the device 40 to expand the mixture. The first stream coming from the device 40 to expand the mixture, is sent to the second separator 60 gas-liquid. The second separator also forms a stream of liquid, which flows directly into the distillation column 38.

The arrangement of the turbine 70 relative to the second stream from the device 40 for expanding the mixture is favorable for increasing the resource of turbine blades (not shown), since the amount of condensate (droplets) in the stream flowing over the blades will be reduced, which will reduce their wear.

In some embodiments, with insufficient pressure in the mixture, in order to ensure the efficient operation of the turboexpander, a compressor may be used to further compress the mixture. FIG. 11, by way of example, is given a schematic depiction of a system 1100 for low-temperature separation of a gas mixture (hereinafter referred to as system 1100 for brevity) in accordance with the tenth embodiment of the invention. System 1100 shown in FIG. 11 is similar to the systems illustrated in FIG. 1 and 3-10, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 11 parts of the description, similar to parts of the description of FIG. 1 and 3-10, for brevity will be omitted. Specialists in the relevant field will understand that system 1100 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1100. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to the system 1100 has the following features. The first input 30a of the first mixer 30 again serves as the input to the system 1100 as a whole, and as the entrance to the first mixer 30. The first compressor 42 is connected in a sequential manner between the first mixer 30 and the first refrigeration unit 34, which, in turn, connected in series to the first heat exchanger 32. The first and second outputs of the first heat exchanger 32 are connected to the first gas-liquid separator 36 and the second compressor 64, respectively. The second outlet 36b of the first gas-liquid separator is connected to the first and second throttle valves 50 and 66, connected in parallel, which, in turn, are connected respectively to the distillation column 38 and to the second heat exchanger 52. Thus, the liquid flow (two-phase flow) from the first gas-liquid separator is divided between the second heat exchanger 52 and the distillation column. The second heat exchanger 52 is enabled to also receive a gas / vapor stream from the first gas-liquid separator before the gas / vapor stream enters the device 40 to expand the mixture.

System 1100 is particularly useful when, during its operation, the initial mixture 1101 is fed at a relatively low differential pressure. More specifically, the original mixture 1101 is mixed with the second stream, selected in the device 40 to expand the mixture. The resulting combined mixture is then compressed in the first compressor 42 before cooling it in the first refrigeration unit 34 and in the first heat exchanger 32.

The fluid flow from the first separator 36 gas-liquid is divided into the first part, which is passed through the first throttle valve 50 and fed into the distillation column 38, and the second part, which is passed through the second throttle valve 66 and fed to the second heat exchanger 52. After passing through the second heat exchanger 52 the second part enters the second mixer 48 where it is mixed with gas-phase products from the distillation column 38. The combined stream is returned to the first mixer 30 for mixing with the original mixture 1101, as it is ylo described above. The gas / vapor stream from the first separator 36 is fed to the device 40 to expand the mixture, in which

- 10 010564 place the process described above with reference to FIG. 1 and 2.

In another, very specific variant, after mixing the initial mixture with the products returned to the initial mixture, the mixture is additionally compressed in the compressor. FIG. 12, by way of example, a schematic representation of a system 1200 for low-temperature separation of a gas mixture (hereinafter referred to as system 1200 for brevity) in accordance with the eleventh embodiment of the invention. System 1200, shown in FIG. 12 is similar to the systems illustrated in FIG. 1 and 3-11, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 12 parts of the description, similar to parts of the description of FIG. 1 and 3-11, for brevity will be omitted. Specialists in the relevant field will understand that system 1200 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1200. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 1200, has the following features. The gas / vapor stream at the outlet of the first gas-liquid separator 36 is divided into two streams. The first stream is fed to the device 40 to expand the mixture. The second stream is fed to the turbine 70, which is installed parallel to the device 40 to expand the mixture. The first outlet 40a of the device 40 for expanding the mixture and the outlet of the turbine 70 are connected to the inputs of the second mixer 48, which, in turn, is connected to the distillation column 38. The second output 40b of the device 40 to expand the mixture and the first output 38a of the distillation column 38 are connected to the inputs of the third the mixer 68, which, in turn, is connected with the series-connected second heat exchanger 52 and the second compressor 64. The system 1200 is applicable in situations in which it is desirable to provide increased pressure in the system to increase the efficiency and separation of the mixture.

When the system is running, after mixing the initial mixture 1201 with a part of the fluid flow from the first gas-liquid separator 36, the resulting mixture is compressed in the compressor 42 and cooled in the first refrigeration unit 34 and in the first heat exchanger 32. The other part of the liquid-flow from the first gas-liquid separator 36 is passed through the throttle valve 50 and fed into the distillation column 38. The gas / vapor flow from the first separator 36 gas-liquid is also divided into two parts. The first part is sent to the turbine 70, and the second to the device 40 to expand the mixture. The first stream from the device 40 to expand the mixture and the stream from the outlet of the turbine 70 is mixed and fed into the distillation column 38. The second stream is mixed with gas-phase products coming from the distillation column 38, and before their release from the system passes through the second heat exchanger 52 and the compressor 64.

In one very specific variant, gas-phase products coming from the distillation column cool, expand and separate the part of the products enriched with components heavier than methane, which are partially or completely sent to the distillation column. FIG. 13, by way of example, is given a schematic depiction of a system 1300 for low-temperature separation of a gas mixture (hereinafter referred to as system 1300 for brevity) in accordance with a twelfth embodiment of the invention. System 1300 shown in FIG. 13 is similar to the systems illustrated in FIG. 1 and 3-12, so that the elements common to all systems have the same numerical designation. Moreover, when considering FIG. 13 parts of the description, similar to parts of the description of FIG. 1 and 3-12, will be omitted for brevity. Specialists in the relevant field will understand that system 1300 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools used to ensure the operation of the system 1300. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The option corresponding to the 1300 system has the following features. The system 1300 comprises a second device 80 for expanding the mixture, similar in construction and function to the device 40 for expanding the mixture described earlier with reference to FIG. 2. Similar to the first device 40 for expanding the mixture, the device 80 for expanding the mixture has first and second outputs 80a, 80b, respectively. The first outlet 80a is intended to supply the first stream containing the heavier components to the second gas-liquid separator 60, while the second outlet 80B serves to combine the second stream containing the lighter components with the gas / vapor stream from the second gas-liquid separator 60 . System 1300 also includes a pump 72 and a third butterfly valve 74, connected in a sequential pattern between the fluid flow (or two-phase flow) from the second gas-liquid separator 60 (i.e., between its second output 60b) and the third heat exchanger 62, which, in turn associated with a distillation column 38. Gas-phase products from the distillation column 38 is also passed through the third heat exchanger 62.

When the system is operating, the gas-phase products coming from the distillation column 38 are cooled, expanded (in the second device 80 for expanding the mixture) and separated, the resulting second stream from the second device 80 for expanding the mixture being sent partially or completely back to the distillation column 38.

- 11 010564

In some embodiments, the gas-phase products from the rectification column are further compressed in the compressor. FIG. 14, as an example, is given a schematic depiction of a system 1400 for low-temperature separation of a gas mixture (hereinafter referred to as system 1400 for brevity) in accordance with a thirteenth embodiment of the invention. System 1400 shown in FIG. 14 is similar to the systems illustrated in FIG. 1 and 3-13, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 14 parts of the description, similar to parts of the description of FIG. 1 and 3-13, for brevity will be omitted. Specialists in the relevant field will understand that system 1400 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1400. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The option corresponding to the 1400 system has the following features. System 1400 has a cooling and compression loop provided between the first outlet 38a of the distillation column 38 and the inlet of the second gas-liquid separator 60 and containing a third heat exchanger 76 connected in series, a second compressor 64 and the second refrigeration unit 44. The output of the second refrigeration unit is included in a return line passing through the third heat exchanger 76. The first outlet 60a (corresponding to the outlet for the gas / vapor flow) of the second gas-liquid separator 60 is connected to the second device 80 for expanding the mixture. The first outlet 80a of this device 80 (corresponding to the heavier components separated as a result of the expansion and separation process) is connected to the distillation column 38, and the stream from its second outlet 80b is combined with the stream from the second outlet 40b of the device 40 to expand the mixture.

When the system is operating, the gas-phase products from the rectification column 38 are cooled and compressed in the indicated cooling and compression circuit. More specifically, gas-phase products from distillation column 38 before being fed to the second gas-liquid separator 60 are cooled in a heat exchanger 76, compressed in a compressor 64, cooled in a refrigeration unit 44, and then further cooled in a third heat exchanger 62. Liquid from the second separator 60 gas-liquid before being fed into the distillation column 38 is also passed through the third heat exchanger 62. The work of the rest of the system 1400 is similar to the work of the system 1300 shown in FIG. 13.

In another very specific embodiment, the gas-phase products from the distillation column are expanded to produce a product enriched in components heavier than methane. This product is partially or fully sent to the distillation column or returned to the gas-phase product stream before its expansion. FIG. 15, by way of example, is given a schematic depiction of a system 1500 for low-temperature separation of a gas mixture (hereinafter referred to as system 1500 for short) in accordance with a fourteenth embodiment of the invention. System 1500, shown in FIG. 15 is similar to the systems illustrated in FIG. 1 and 3-14, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 15 parts of the description, similar to parts of the description of FIG. 1 and 3-14, for brevity, will be omitted. Specialists in the relevant field will understand that system 1500 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 1500. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 1500, has the following features. The first outlet 38a of the distillation column 38 is connected in the system 1500 to the entrance of the second device 80 for expanding the mixture through the second refrigeration unit 44. The first outlet 80a of this device 80 is connected to the second gas-liquid separator 60. In this case, just as it was shown in FIG. 14, the flow of liquid (two-phase flow) from the outlet of this separator 60 is fed to the distillation column 38.

When the system is operating, the gas-phase products coming from the distillation column 38 are expanded in the second device 80 to expand the mixture in order to separate the heavy and light components, as described above with reference to FIG. 2. The first stream (containing the heavier components) from the first outlet 80a of the second device 80 for expanding the mixture is passed through the second gas-liquid separator 60. The output fluid flow (two-phase flow) is pumped into the distillation column 38 through the pump 72 and the third throttle valve 74. The stream coming from the second outlet 80b of the device 80 for expanding the mixture is combined with the gas / vapor flows coming from the second separator 60 and from the second outlet 40b device 40 to expand the mixture. The resulting mixture is returned to the first heat exchanger 32 for cooling the original mixture 1501. The initial mixture 1501, mixed with the return flow (as described above), is also compressed before being fed into the first separator 36 gas-liquid. The remaining operations are similar to those performed in the previously described systems.

In other embodiments, the enriched stream obtained after expansion of the gas-phase product coming from the distillation column is sent to the initial mixture prior to its expansion. On

- 12 010564 FIG. 16, by way of example, is given a schematic depiction of a system 1600 for low-temperature separation of a gas mixture (hereinafter referred to as system 1600 for brevity) in accordance with the fifteenth embodiment of the invention. The system 1600 shown in FIG. 16 is similar to the systems illustrated in FIG. 1 and 3-15, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 16 parts of the description, similar to parts of the description of FIG. 1 and 3-15, for brevity, will be omitted. Specialists in the relevant field will understand that system 1600 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the operation of the system 1600. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

Option corresponding to the system 1600, has the following features. Unlike system 1500, system 1600 contains only the first gas-liquid separator 36. The third heat exchanger 62 is connected in series between the first outlet 38a of the distillation column 38 and the inlet of the second device 80 for expanding the mixture. The flow from the first outlet 80a of this device 80 is returned via the third throttle valve 74, the third heat exchanger 62 and the second heat exchanger 52, which is connected by a return line to the first mixer 30.

In operation, the first stream formed in the second device 80 to expand the mixture, before combining it with the original mixture 1601, is passed through the third and second heat exchangers 62, 52, respectively. The output fluid flow (two-phase flow) from the first separator 36 gas is also combined with the first flow formed in the second device 80 to expand the mixture, before supplying this flow to the second heat exchanger 52. The second throttle valve 66 reduces the pressure in the output fluid flow to the first gas-liquid separator 36. The remaining elements function as described with reference to FIG. 15.

In some embodiments, before expansion or after expansion, the mixture or part thereof is passed through a turbine expander turbine. FIG. 17, by way of example, is given a schematic depiction of a system 1700 for low-temperature separation of a gas mixture (hereinafter referred to as system 1700 for brevity) in accordance with the sixteenth embodiment of the invention. The system 1700 shown in FIG. 17 is similar to the systems illustrated in FIG. 1 and 3-16, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 17 parts of the description, similar to parts of the description of FIG. 1 and 3-16, for brevity, will be omitted. Specialists in the relevant field will understand that system 1700 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1700. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to the system 1700 has the following features. System 1700 contains four gas-liquid separators, i.e. the first and second separators 36, 60, respectively, and additionally the third and fourth separators 82, 84 gas-liquid, respectively. The first and second gas-liquid separators 36, 60 are connected in such a way that the gas / vapor output stream of the first gas-liquid separator 36 is fed to the second gas-liquid separator 60. As shown in FIG. 17, a turbine 70 and a second mixer 48 are turned on between these separators. Liquid flows from the outlets of the first and second separators 36, 60 are gas-liquid combined and fed to the third separator 82. The output liquid stream from the third separator 82 is fed to the fourth separator 84 through the second heat exchanger 52. The liquid effluent from the fourth separator 84 is fed to the distillation column 38, and its gas / vapor effluent is fed through the second mixer 48 to the second gas-liquid separator 60. The gas / vapor output stream from the second gas-liquid separator 60 is fed to the device 40 to expand the mixture. The compressor stage of the turbo-expander, which serves to expand the mixture, can be used as a compressor 42. This scheme allows to improve the energy consumption in the process of low-temperature separation.

During operation of the system, the initial mixture 1701 is sequentially cooled in the first and second heat exchangers 32, 52 before feeding it to the first gas-liquid separator 36. Liquid streams from the first and second gas-liquid separators 36, 60 are combined and sent to the third gas-liquid separator 82 together with the first stream formed by the device 40 for expanding the mixture. The third gas-liquid separator 82 forms a liquid stream, which is used as a refrigerant in the second heat exchanger 52 before it is supplied for further processing to the fourth gas-liquid separator 84. The liquid stream formed by the fourth gas-liquid separator 84 is then fed to the distillation column 38. Gas / vapor streams from the third and fourth gas-liquid separators 82, 84 are combined and returned to the second gas-liquid separator 60 together with the gas / vapor stream the first separator 36 gas-liquid.

In another embodiment, a liquid phase is separated from the mixture, a part of which is passed through a throttle valve, and the resulting products are used to cool the mixture and sent to the mixture before its expansion. FIG. 18 As an example, a schematic representation of the system 1800 for a low tempo is given

- 13 010564 country separation of the gas mixture (hereinafter referred to as the 1800 system for short) in accordance with the seventeenth embodiment of the invention. System 1800, shown in FIG. 18 is similar to the systems illustrated in FIG. 1 and 3-17, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 18 parts of the description, similar to parts of the description of FIG. 1 and 3-17, for brevity, will be omitted. Specialists in the relevant field will understand that the system 1800 also contains the appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 1800. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to the system 1800 has the following features. The liquid output from the output 36b of the first gas-liquid separator 36 is fed to the distillation column 38 and to the third heat exchanger 62. The third heat exchanger 62 is connected in a sequential scheme between the first heat exchanger 32 and the first gas-liquid separator 36. In this case, the third heat exchanger 62 returns the fluid flow from the outlet 36b to the first mixer 30 through the first compressor 42 and the second refrigeration unit 44.

In operation, the fluid flow from the first gas-liquid separator 36 is used, as shown in FIG. 18, to cool the initial mixture 1801. The initial mixture 1801 is first cooled, passing through the first refrigeration unit 34, and then mixed with a portion of the liquid stream from the first gas-liquid separator 36. This part of the fluid flow, however, is first used as a refrigerant in the third heat exchanger 62, and then compressed and cooled before being added to the original mixture 1801. The remaining parts of the system work as described above with reference to FIG. 3

In accordance with other options, the mixture is divided into at least two streams prior to expansion, one of which is pumped through a turbine expander turbine and sent to a distillation column, and the other is expanded by pumping a vortex mixture flow through a nozzle channel. At the exit of the nozzle channel or its part, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components; enriched stream is then sent to the distillation column. FIG. 19, by way of example, is given a schematic depiction of a system 1900 for low-temperature separation of a gas mixture (hereinafter referred to as system 1900 for brevity) in accordance with an eighteenth embodiment of the invention. The system 1900 shown in FIG. 19 is similar to the systems illustrated in FIG. 1 and 3-18, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 19 parts of the description, similar to parts of the description of FIG. 1 and 3-18, for brevity will be omitted. Specialists in the relevant field will understand that system 1900 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the 1900 system. However, the drawing shows only those elements that are necessary to describe various aspects. this option.

The variant corresponding to the 1900 system has the following features. The gas / vapor stream from the first gas-liquid separator 36 is divided into two streams. The first stream is fed to the device 40 to expand the mixture. The second stream is fed to the turbine 70, which is installed parallel to the device 40 to expand the mixture. The first outlet 40a of the device 40 for expanding the mixture and the outlet of the turbine 70 are connected with a distillation column 38. The second outlet 40b of the device 40 for expanding the mixture and the first outlet 38a of the distillation column are mixed in a second mixer 48 which is connected in series to the first heat exchanger 32. System 1900 applicable in situations where it is desirable to provide increased pressure inside the system in order to increase the efficiency of separation of the mixture.

In operation, the initial mixture 1901 is cooled in the first heat exchanger 32 and separated in the first gas-liquid separator 36. The fluid flow from separator 36 passes through valve 50 to the distillation column 38. The gas / vapor flow generated by the first gas-liquid separator 36 is divided into at least two streams before expansion, one of which is pumped to expand it through the turbine 70 of the turbine expander and sent to distillation column 38. The second stream is mixed with gas-phase products from distillation column 38, and the resulting mixture is passed through the first heat exchanger 32 and removed from the system after compression in the first compressor 42. This method it is applicable for deeper cleaning of a mixture and for removal from it, in essence, of all heavier components.

Accordingly, in some embodiments, the stream enriched during expansion and part of the mixture passing through the turbine of the turbine expander are mixed in an ejector. FIG. 20, as an example, is given a schematic depiction of a system 2000 for low-temperature separation of a gas mixture (hereinafter referred to as system 2000 for short) in accordance with a nineteenth embodiment of the invention. The system 2000 shown in FIG. 20 is similar to the systems illustrated in FIG. 1 and 3-19, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 20 parts of the description, similar to parts of the description of FIG. 1 and 3-19, for brevity will be omitted.

- 14 010564

Specialists in the relevant field will understand that System 2000 also contains the appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the System 2000. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to system 2000 has the following features. System 2000 is almost identical to system 1900, except that compressor 42 is not included. When operating, system 2000, like system 1900, is capable of providing improved efficiency of a turbine 70 of a turbo-expander to expand the mixture, thereby providing a deeper cooling of gas in turbine 70 and allowing you to achieve a greater degree of compression.

In another embodiment, the mixture flow before expansion is divided into at least three streams, one of which is passed through a valve with a controlled flow rate and is either sent to a distillation column or mixed with a gas-phase product coming from the distillation column. FIG. 21, as an example, is given a schematic depiction of a system 2100 for low-temperature separation of a gas mixture (hereinafter referred to as system 2100 for brevity) in accordance with the twentieth embodiment of the invention. The system 2100 shown in FIG. 21 is similar to the systems illustrated in FIG. 1 and 3-20, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 21 parts of the description, similar to parts of the description of FIG. 1 and 3-20, for brevity, will be omitted. Specialists in the relevant field will understand that system 2100 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 2100. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The option corresponding to the 2100 system has the following features. The stream coming from the first exit 36a of the first gas-liquid separator 36 is divided between the turbine 70, the device 40 for expanding the mixture and the third mixer 68. The third mixer 68 also receives the first stream from the device 40 for expanding the mixture and the gas-phase products from the distillation column 38.

When the system is operating, the gas / vapor flow formed by the first separator 36 is divided into three parts, which are passed through the turbine 70, the device 40 to expand the mixture and the third mixer 68. The remaining components of the system function as described above with reference to FIG. 19 and 20. This method allows to stabilize the flow rate through the turbine 70 of the expander when the parameters of the initial mixture 2101, for example, its flow, are changed.

In accordance with other variants of the method, the liquid phase is separated from the mixture, a part of which is passed through a throttle valve, and part of the products obtained is used to cool the mixture and sent to the mixture before its expansion. FIG. 22, by way of example, a schematic representation of a system 2200 for low-temperature separation of a gas mixture (hereinafter referred to as 2200 for brevity) in accordance with the twenty-first embodiment of the invention. System 2200, shown in FIG. 22 is similar to the systems illustrated in FIG. 1 and 3-21, so that elements common to all systems have the same numerical designation. Moreover, when considering FIG. 22 parts of the description, similar to parts of the description of FIG. 1 and 3-21, for brevity, will be omitted. Specialists in the relevant field will understand that system 2200 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 2200. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The variant corresponding to the system 2200 has the following features. The second outlet 36b (i.e. the outlet for the liquid phase) of the first gas-liquid separator 36 and the first outlet 40a of the device 40 for expanding the mixture are connected to the second mixer 48, the output of which, in turn, is connected to the first heat exchanger 32.

When the system is operating, the resulting mixture of the liquid phase from the first gas-liquid separator 36 and the first stream from the device 40 to expand the mixture is used to cool the initial mixture 2201 in the first heat exchanger 32. In addition, this mixture is added to the initial mixture 2201 in the first mixer 30. Such The method can be effective in cases when gas-phase products leaving the distillation column contain relatively light components of the initial mixture 2201. For example, when processing natural gas, gas-phase products coming from rectifier Discount column 38 may have a very small content of components heavier than methane.

In another embodiment, the mixture is separated from the mixture the liquid phase, which is passed through the throttle valve, and the resulting products are used to cool the mixture. FIG. 23, by way of example, a schematic representation of a system 2300 for low-temperature separation of a gas mixture (hereinafter referred to as a system 2300 for brevity) in accordance with the twenty-second embodiment of the invention. The system 2300 shown in FIG. 23 is similar to the systems illustrated in FIG. 1 and 3-22, so that elements common to all systems have the same numerical designation. In this case, when considering

- 15 010564 nii FIG. 23 parts of the description, similar to parts of the description of FIG. 1 and 3-22, for brevity, will be omitted. Specialists in the relevant field will understand that the system 2300 also contains an appropriate combination of interrelated structural elements, mechanical systems, hardware, hardware and software, and software tools that are used to ensure the functioning of the system 2300. However, the drawing shows only those elements that are necessary to describe various aspects of this option.

The option corresponding to the 2300 system has the following features. A portion of the stream coming from the second outlet 36b of the first gas-liquid separator 36, and the stream coming from the first outlet 40a of the device 40 for expanding the mixture, are combined and passed through the second and third heat exchangers 52 and 62. The first outlet 38a of the distillation column 38 and the corresponding outlet the third heat exchanger 62 is connected and connected to the first compressor 42. The first compressor 42 is connected in series with the second refrigeration unit 44 connected to the first mixer 30, into which the initial mixture 2301 also flows.

In operation, a portion of the liquid stream from the first gas-liquid separator 36 is combined with the first stream formed by the device 40 for expanding the mixture. The resulting mixture is used to cool the gas / vapor stream from the first gas-liquid separator 36 in the second heat exchanger 52 and the original mixture 2301 in the third heat exchanger 62 before combining with the initial mixture 2301 in mixer 30. The system 2300 is applicable for treating gas mixtures when the concentration of the target components in the initial mixture is negligible.

The above description only illustrates the practical applications of the principles of the invention. Considering the data presented, numerous modifications and variations of the present invention are possible. In this regard, it should be clear that, without going beyond the scope of the attached claims, it is possible to implement the invention differently than according to the above options.

Claims (64)

CLAIM 1. The method of low-temperature separation of a mixture of hydrocarbon gases, comprising cooling the mixture; expansion of the mixture or its part without mechanical work; partial condensation of the mixture during its expansion; separation of the mixture or its part in a distillation column to obtain products in the liquid and gas phase, characterized in that the process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the mixture flow is twisted at the outlet from the nozzle channel or a part thereof, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components, the enriched stream is partially or completely directed to distillation vessel onnu, and gas-phase products, obtained in the distillation column, partially or completely directed to the mixture before its expansion. 2. The method according to claim 1, characterized in that after separation of the streams, at least one of them is compressed, passing the stream through a diffuser. 3. The method according to claim 1, characterized in that before expansion, the mixture or part thereof is mixed in an ejector with gas-phase products coming from a distillation column. 4. The method according to claim 1, characterized in that prior to expansion and / or after it, the liquid phase is separated from the mixture or its part, the latter is passed through a throttle valve, and the products obtained after the valve are partially or completely sent to the distillation column. 5. The method according to claim 1, characterized in that the gas-phase products coming from the distillation column are further cooled. 6. The method according to claim 4, characterized in that at least part of the gas-phase products coming from the distillation column are sent to the mixture until it expands along with part of the products obtained after the butterfly valve. 7. The method according to claim 4, characterized in that at least a portion of the liquid phase separated from the mixture is used to further cool the mixture or part thereof and is sent to the mixture until it expands. 8. The method according to claim 6 or 7, characterized in that before expansion or after expansion, the mixture or part of it is passed through a turbine of an expander. 9. The method according to claim 8, characterized in that prior to expansion the mixture is further compressed in a compressor. 10. The method according to claim 1, characterized in that after mixing with the products sent to the initial mixture until it expands, the resulting mixture is additionally compressed in a compressor. 11. The method according to claim 10, characterized in that the gas-phase products from the distillation column are cooled, expanded, and a portion of the products enriched with components heavier than methane is recovered, which are partially or completely sent to the distillation column. 12. The method according to claim 11, characterized in that the gas-phase products coming from the distillation column, before cooling, are additionally compressed in a compressor. - 16 010564 13. The method according to p. 12, characterized in that the gas-phase products coming from the distillation column are expanded to obtain a product enriched with components heavier than methane, the latter is partially or completely sent to the distillation column or returned to the gas-phase product stream before expansion. 14. The method according to item 13, wherein the part of the products obtained after expansion of the gas-phase product, enriched in components heavier than methane, is returned to the initial mixture before expansion. 15. The method according to claim 5, characterized in that prior to expansion or after expansion, the mixture or part thereof is passed through a turbine expander turbine. 16. A method of low-temperature separation of a mixture of hydrocarbon gases, comprising cooling the mixture; expansion of the mixture or its part without mechanical work; partial condensation of the mixture during its expansion; separation of the mixture or its part in a distillation column to obtain products in the liquid and gas phase, characterized in that the process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the mixture flow is twisted at the outlet from the nozzle channel or a part thereof, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components, the enriched stream is partially or completely directed to distillation vessel onnu, and gas-phase products, coming from the rectifying tower, is partially or completely mixed with the depleted flow. 17. The method according to clause 16, characterized in that after separation of the streams at least one of them is compressed, passing the stream through the diffuser. 18. The method according to p. 16, characterized in that before and / or after expansion from the mixture or part thereof, the liquid phase is separated, the latter is passed through a throttle valve, and the products obtained after the valve are partially or completely sent to the distillation column. 19. The method according to clause 16, wherein the gas-phase products coming from the distillation column, further cooled. 20. The method according to p. 18, characterized in that at least part of the gas-phase products coming from the distillation column are sent to the mixture until it expands along with part of the products obtained after the butterfly valve. 21. The method according to p. 18, characterized in that at least a portion of the liquid phase separated from the mixture is used for additional cooling of the mixture or part thereof and sent to the mixture until it expands. 22. The method according to clause 16, wherein the liquid phase is separated from the mixture during the expansion process or after it, the latter is passed through a throttle valve, part of the products obtained after the throttle valve are used to cool the mixture or its part and sent to its expansion. 23. The method according to clause 16, wherein the mixture stream is divided into at least two parts, one of which is pumped through the expander turbine and sent to a distillation column, and the other is expanded in a swirl flow pumped through the nozzle channel, to obtain part the stream enriched with components heavier than methane; the enriched stream is sent to a distillation column. 24. The method according to item 23, wherein the enriched stream obtained in the expansion process, and the stream passing through the turbine of the expander, are mixed in an ejector. 25. The method according to item 23, wherein the mixture stream is divided into at least three streams, one of which is directed through a valve with controlled flow into the distillation column or mixed with products coming from the distillation column in the gas phase. 26. The method according to clause 16 or 22, characterized in that prior to expansion or after expansion, the mixture or part thereof is passed through a turbine expander turbine. 27. The method according to p. 26, characterized in that before expansion, the mixture is additionally compressed in a compressor. 28. The method according to any one of paragraphs.16, 22, 24, 25, characterized in that after mixing with products sent to the original mixture until it expands, the resulting mixture is additionally compressed in a compressor. 29. The method according to p. 28, characterized in that the gas-phase products coming from the distillation column, cool, expand and emit a portion of the products enriched in components heavier than methane, which are partially or completely sent to the distillation column. 30. The method according to clause 29, wherein the gas-phase products coming from the distillation column, before cooling, are additionally compressed in a compressor. 31. The method according to p. 30, characterized in that the gas-phase products coming from the distillation column, expand to obtain a product enriched with components heavier than methane, the latter is partially or completely sent to the distillation column or returned to the flow of gas-phase products before expansion. - 17 010564 32. The method according to p. 31, characterized in that the part of the products obtained after expansion of the gas-phase product enriched in components heavier than methane is returned to the initial mixture until it expands. 33. The method according to claim 19, characterized in that prior to expansion or after expansion, the mixture or part thereof is passed through a turbine of an expander. 34. The method of low-temperature separation of a mixture of hydrocarbon gases, comprising cooling the mixture; expansion of the mixture or its part without mechanical work; partial condensation of the mixture during its expansion; separation of the mixture or its part in a distillation column to obtain products in the liquid and gas phase, characterized in that the process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the mixture flow is twisted at the outlet from the nozzle channel or part thereof, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components, the enriched stream is partially or completely directed into the mixture until it is expanded I, and the gas-phase products, coming from the rectifying tower, is partially or completely mixed with the depleted flow. 35. The method according to clause 34, wherein after separation of the streams, at least one of them is compressed, passing the stream through the diffuser. 36. The method according to clause 34, wherein the liquid phase is separated from the mixture or its part prior to expansion or after it, the latter is passed through a throttle valve, and the products obtained after the valve are partially or completely sent to the distillation column. 37. The method according to clause 34, wherein the gas-phase products coming from the distillation column, further cooled. 38. The method according to clause 36, wherein at least a portion of the gas-phase products coming from the distillation column are sent to the mixture until it expands along with part of the products obtained after the butterfly valve. 39. The method according to clause 36, wherein at least a portion of the liquid phase separated from the mixture is used to further cool the mixture or part thereof and sent to the mixture until it expands. 40. The method according to clause 34, wherein the liquid phase is separated from the mixture during cooling or after it, the latter is passed through a throttle valve, part of the products obtained after the throttle valve are used to cool the mixture and sent to the mixture until it expands. 41. The method according to clause 34 or 40, characterized in that before expansion or after expansion of the mixture or part of it is passed through a turbine of an expander. 42. The method according to paragraph 41, wherein the mixture is further compressed in the compressor prior to expansion. 43. The method according to any one of paragraphs 34, 40, characterized in that after mixing with the products sent to the original mixture until it expands, the resulting mixture is additionally compressed in a compressor. 44. The method according to item 43, wherein the gas-phase products coming from the distillation column, cool, expand and separate the part of the products enriched with components heavier than methane, which is partially or completely sent to the distillation column. 45. The method according to item 43, wherein the gas-phase products coming from the distillation column, before cooling, are additionally compressed in a compressor. 46. The method according to item 45, wherein the gas-phase products coming from the distillation column, expand to obtain a product enriched with components heavier than methane, the latter is partially or fully sent to the distillation column or returned to the flow of gas-phase products before expansion. 47. The method according to item 46, wherein the part of the products obtained after expansion of the gas-phase product enriched in components heavier than methane is returned to the initial mixture before expansion. 48. The method according to clause 37, wherein the mixture or part of it is passed through the turbine of the expander before expansion or after expansion. 49. The method of low-temperature separation of a mixture of hydrocarbon gases, comprising cooling the mixture; expansion of the mixture or its part without mechanical work; partial condensation of the mixture during its expansion; separation of the mixture or its part in a distillation column to obtain products in the liquid and gas phase, characterized in that the process of expansion of the mixture is carried out by passing the mixture through the nozzle channel, and in the nozzle channel and / or at the entrance to the nozzle channel the mixture flow is twisted at the outlet from the nozzle channel or a part thereof, the mixture stream is divided into at least two streams, one of which is enriched in components heavier than methane, and the other is depleted in these components, the enriched stream and gas-phase products coming from distillation to the olonns are partially or completely directed into the mixture until it expands. 50. The method according to 49, characterized in that after separation of the streams at least one of them - 18 010564 compress, passing the stream through the diffuser. 51. The method according to 49, characterized in that before expansion, the mixture or part thereof is mixed in an ejector with gas-phase products coming from a distillation column. 52. The method according to 49, characterized in that prior to expansion and / or after the liquid phase is separated from the mixture or its part, the latter is passed through the throttle valve, and the products obtained after the valve are partially or completely sent to the distillation column. 53. The method according to 49, characterized in that the gas-phase products from the distillation column are further cooled. 54. The method according to 49, characterized in that at least a portion of the gas-phase products coming from the distillation column are sent to the mixture before throttling along with part of the products obtained after the throttle valve. 55. The method according to paragraph 52, wherein at least a portion of the liquid phase separated from the mixture is used to further cool the mixture or part thereof and is sent to the mixture until it expands. 56. The method according to 49, characterized in that prior to expansion or after expansion from the mixture, the liquid phase is separated, the latter is passed through the throttle valve, the products obtained after the throttle valve are used to cool the mixture or part thereof. 57. The method according to § 49 or 56, characterized in that before expansion or after expansion, the mixture or part of it is passed through a turbine of an expander. 58. The method according to p, characterized in that before expansion, the mixture is additionally compressed in a compressor. 59. The method according to any one of paragraphs 49, 56, characterized in that after mixing with the products sent to the original mixture until it expands, the resulting mixture is additionally compressed in a compressor. 60. The method according to p. 59, characterized in that the gas-phase products coming from the distillation column, cool, expand and separate the part of the products enriched with components heavier than methane, which is partially or completely sent to the distillation column. 61. The method according to p. 60, characterized in that the gas-phase products coming from the distillation column, before cooling, are additionally compressed in a compressor. 62. The method according to p. 61, characterized in that the gas-phase products coming from the distillation column, expand to obtain a product enriched with components heavier than methane, the latter is partially or fully sent to the distillation column or returned to the flow of gas-phase products before expansion. 63. The method according to claim 62, characterized in that a portion of the products obtained after expansion of the gas-phase product enriched in components heavier than methane is returned to the initial mixture before expansion. 64. The method according to item 53, wherein before expansion or after expansion, the mixture or part of it is passed through a turbine of an expander.