Method and apparatus for recovering helium concentrate from helium-containing gas

Abstract

The group of inventions relates to natural gas processing technologies. A method for recovering helium concentrate from dry gas is carried out in a helium concentrate recovery apparatus comprising a high-temperature heat exchanger, a medium-temperature heat exchanger, a low-temperature heat exchanger, a heavy component absorber that separates a feed stream into a heavy component stream and a helium-enriched stream, a helium recovery stripping column for obtaining a helium-saturated stream and a methane-saturated stream, and a non-condensable component separator. The stripping column is connected by an outlet for a part of a stripping column bottom liquid stream, via a valve, to an inlet of the medium-temperature heat exchanger, which serves as a reboiler for the stripping column. Streams of gas from the separator and the stripping column are mixed and fed to a helium recovery condenser column for separation into a helium concentrate and a bottom liquid stream predominantly containing nitrogen and methane. The condenser column is equipped with a condenser and a separator for helium recovery. The inventions make it possible to increase the recovery of helium concentrate from a gas feed stream at a pressure below 3.0 MPa (absolute).

Description

[0001] METHOD AND APPARATUS FOR EXTRACTING HELIUM CONCENTRATE FROM HELIUM-CONTAINING GAS

[0002] Field of technology.

[0003] The invention relates to natural gas processing technologies, namely to cryogenic gas separation technologies for the purpose of extracting helium concentrate, and can be used in gas production and gas processing plants.

[0004] State of the art.

[0005] There are many known technological solutions in the field of condensation-evaporation methods (cryogenic) for extracting helium concentrate with various operating principles for industrial processing of natural gas.

[0006] A plant is known (application CN 114646187, published on June 21, 2022) that implements low-temperature methods for extracting helium concentrate from a natural gas stream with a low helium content.

[0007] The common features of the known and proposed installations are:

[0008] - the presence of three distillation columns;

[0009] - the presence of three recuperative heat exchangers to reduce the temperature of the gas flow.

[0010] However, the existing plant proposes using two-section distillation columns, which increases capital costs. The use of mixed and nitrogen refrigeration units for operation increases energy consumption. The technical solution does not include a recirculated helium concentrate stream from the pure helium production unit, which in turn impacts the recovery factor of the helium concentration and production unit.

[0011] The closest analogue of the proposed group of inventions is a method for extracting helium from natural gas, including sequential cooling of natural gas in heat exchangers and separating it into components in distillation columns, and a helium extraction unit containing three distillation columns, two multi-flow heat exchangers, and a nitrogen refrigeration machine (application CN111578621, published on August 25, 2020).

[0012] The common features of the known and proposed installations are:

[0013] - the presence of three distillation columns;

[0014] - the presence of recuperative heat exchangers to reduce the temperature of the gas flow.

[0015] However, the flow management in the pre-cooling heat exchanger complicates the process design. The use of a nitrogen refrigeration machine increases the capital costs of the installation, while the use of two-section distillation columns leads to higher capital costs.

[0016] The common features of the known and proposed methods are:

[0017] - sequential cooling of the product flow in heat exchangers;

[0018] - sequential extraction of helium in three distillation columns;

[0019] - separation of the raw natural gas stream into several streams in the processes of cryogenic extraction of the target product.

[0020] However, the existing technological solution does not provide for energy recovery from the bottoms liquid stream of the heavy hydrocarbon removal column. The use of high pressures (3.0 to 6.0 MPa (abs.)) for low-temperature distillation processes increases the cost of the plant's equipment. The elimination of a recirculated stream of the nitrogen-helium mixture negatively impacts the plant's helium recovery rate.

[0021] The essence of the invention.

[0022] The technical problem that the proposed group of inventions is aimed at solving consists of implementing cryogenic processes for extracting helium from a raw gas stream at pressures below 3.0 MPa (abs.) with an extraction coefficient for the target product of at least 0.97 without using complex dynamic equipment in the technological process, ensuring processes for extracting components for gas compositions with different contents of methane, helium and hydrogen.

[0023] The technical result of the group of inventions is an increase in the extraction of the target product in the process of extracting helium from a raw gas stream at a pressure below 3.0 MPa (abs.).

[0024] The said technical result is achieved by using the proposed method for extracting helium concentrate from dry stripped gas (DSG), which consists in the fact that the initial feed stream of dry stripped gas containing methane, C2+ hydrocarbons, nitrogen in an amount of less than 70% by mole, helium and hydrogen in an amount of less than 50% by mole, is fed to a helium concentrate extraction unit, divided into two parts, one of which is cooled and condensed in a high-temperature heat exchange apparatus, then throttled and fed to an absorber of heavy components for separation, and the other part of the initial feed stream is throttled and fed to the bottom of the absorber of heavy components, in which the flow of bottom liquid with a low helium content is throttled and heated in a high-temperature heat exchange apparatus, after which it is withdrawn as a flow of raw gas without high-pressure helium, and the flow of steam saturated with helium is taken from the upper part of the said absorber,cooled and condensed in a medium-temperature heat exchanger, after which the vapor-liquid stream is directed to a separator of non-condensable components, the liquid stream from which is throttled and fed for separation to a stripping column for helium extraction, part of the liquid stream from which is directed for heating to a medium-temperature heat exchanger, which acts as a reboiler for the column, and is returned to the column, the bottom liquid stream is throttled and fed for heating to the medium-temperature heat exchanger, the vapor stream saturated with helium is withdrawn from the stripping column, mixed with the vapor stream from the separator of non-condensable components, then cooled and partially condensed in a low-temperature heat exchanger, the cooled vapor-liquid stream is fed to a condensation column for helium extraction, including a condenser, into which a refrigerant stream is fed for cooling and partially condensing the gas stream at the top of the condensation column,wherein the gas stream in the upper part of the column is cooled and partially condensed in the condenser of the column as a result of heat exchange with the refrigerant stream, then fed to the separator of the condensation column for phase separation, the liquid stream from which is fed to refrigerate the condensation column, and the vapor stream from the separator of the condensation column, which is a helium concentrate, is removed and successively heated in low-temperature, medium-temperature and high-temperature heat exchangers, the bottom liquid stream of the condensation column for helium extraction is throttled, successively heated in low-temperature, medium-temperature heat exchangers, mixed with the heated stream from the bottom of the stripping column, heated in a high-temperature heat exchanger and the stream is removed after heating as a stream of raw gas without low-pressure helium.

[0025] In a particular case, it is possible to supply an additional flow of nitrogen-helium mixture, which is cooled in a heat exchanger for cooling the nitrogen-helium mixture and mixed with the gas flow from the low-temperature heat exchanger.

[0026] It is also possible to feed low-pressure helium-free feed gas streams from the stripping column and the helium recovery condensation column after heating in a high-temperature heat exchanger for compression into a helium-free feed gas compression unit and mix with a high-pressure helium-free feed gas stream from the heavy component absorber, after which the stream is removed from the unit.

[0027] In a particular case, the flow of nitrogen-helium mixture is fed for compression into the nitrogen-helium mixture compression unit before the flow temperature is lowered in the heat exchange apparatus for cooling the nitrogen-helium mixture.

[0028] It is also possible to cool the condenser of the condensation column with a flow of liquid nitrogen.

[0029] In this case, the liquid nitrogen flow is throttled to form a vapor-liquid flow, which is fed for separation into a liquid nitrogen separator, the liquid nitrogen flow from the separator is fed into the column condenser, after which it is mixed with the gaseous nitrogen flow from the liquid nitrogen separator and fed to cool the nitrogen-helium mixture flow in the heat exchange apparatus for cooling the nitrogen-helium mixture.

[0030] Moreover, the nitrogen stream, after heating in a heat exchanger for cooling the nitrogen-helium mixture, is heated in a heat exchanger and removed from the unit. This technical result is also achieved by using a unit for extracting helium concentrate from dry stripped gas (DSG), which contains methane, C2+ hydrocarbons, nitrogen in an amount less than 70% by mole, helium, and hydrogen in an amount less than 50% by mole, containing:

[0031] - a collector for distributing the raw flow of the SOG, the entrance to which is also the entrance of the raw flow of the SOG into the unit;

[0032] - a high-temperature heat exchanger connected by a direct flow inlet to a feedstock flow distribution manifold, the outlet of the first return flow from which is the outlet of the first feedstock gas flow without high-pressure helium from the unit; the outlet of the second return flow from which is the outlet of the second feedstock gas flow without low-pressure helium from the unit;

[0033] - an absorber of heavy components, connected by the inlet of the cooled raw gas flow in the upper part of the absorber through a valve to the outlet of the direct flow of the high-temperature heat exchanger, the inlet of the raw gas flow through a valve to the distribution manifold of the raw gas flow, the outlet of the bottom liquid, which is a flow of raw gas without high-pressure helium, through a valve to the inlet of the first return flow into the high-temperature heat exchanger;

[0034] - a medium-temperature heat exchanger, which is connected by a direct flow inlet to the outlet of a gas flow saturated with helium from the absorber;

[0035] - a collector of gas flows without low-pressure helium, comprising an inlet of the first return gas flow from the medium-temperature heat exchanger, an inlet of the second gas flow from the medium-temperature heat exchanger and an outlet of the gas flow from the collector, connected to the inlet of the second flow into the high-temperature heat exchanger;

[0036] - a helium recovery stripping column, which is connected by the outlet of the first part of the bottoms liquid flow of the stripping column through a valve to the inlet of a medium-temperature heat exchanger that functions as a reboiler of the stripping column, the inlet of the first part of the bottoms liquid flow to the outlet of the medium-temperature heat exchanger, and the outlet of the second part of the bottoms liquid flow through a valve to the inlet of the first return flow of raw gas without low-pressure helium of the medium-temperature heat exchanger;

[0037] - a separator of non-condensable components, the inlet of which is connected to the outlet of the vapor-liquid flow saturated with helium from the medium-temperature heat exchanger, and the liquid outlet is connected to the inlet to the upper part of the helium extraction stripping column;

[0038] - a collector of gas flows with an increased helium content, comprising an inlet of a gas flow with an increased helium content from a separator of non-condensable components, an inlet of a gas flow with an increased helium content from a helium extraction stripping column and an outlet of a gas flow from the collector, connected to the inlet of a low-temperature heat exchanger;

[0039] - a low-temperature heat exchange apparatus, which contains an inlet of a gas flow with an increased helium content from a collector, an outlet of a vapor-liquid flow with an increased helium content, connected to the bottom of a condensation column for extracting helium through a valve, and an outlet of a first return flow, connected to the inlet of a second return flow into a medium-temperature heat exchange apparatus through a valve;

[0040] - a condensation column for extracting helium, which is connected by an inlet in the bottom part of the flow saturated with helium to the outlet of the direct flow of the low-temperature heat exchanger, by the outlet of the gas flow it is connected to the inlet of the column condenser, and by the outlet of the bottom liquid it is connected to the inlet of the first return flow of the low-temperature heat exchanger through a valve, wherein the outlet of the bottom liquid from the first return flow of the low-temperature heat exchanger is connected to the inlet of the second return flow of the medium-temperature heat exchanger through a valve, the outlet of which is connected to the inlet of the second return flow of the high-temperature heat exchanger, the outlet of which is the outlet of the raw gas unit without low-pressure helium;

[0041] - a condenser of the helium recovery condensation column, which comprises an inlet of a gas stream from the condensation column, an outlet of a stream connected to the inlet of the separator of the helium recovery condensation column, an inlet of a refrigerant stream and an outlet of a refrigerant stream; - a separator of the condensation column, which comprises an inlet of a vapor-liquid stream from the condenser of the column; an outlet of a liquid stream connected to the inlet of the upper part of the condensation column, an outlet of a stream of helium concentrate connected to the inlet of the second return stream into the low-temperature heat exchanger through a valve;wherein the outlet of the second return flow of helium concentrate from the low-temperature heat exchange apparatus is connected to the inlet of the third return flow of the medium-temperature heat exchange apparatus through a valve, the outlet of which is connected to the inlet of the third return flow of the high-temperature heat exchange apparatus, the outlet of the flow of helium concentrate from which is the outlet of the main production flow from the installation.

[0042] Moreover, the installation may additionally include:

[0043] - a heat exchange apparatus for cooling a nitrogen-helium mixture, which contains an inlet for a nitrogen-helium mixture flow, which is the inlet for the nitrogen-helium mixture flow into the unit, a flow outlet connected to the inlet into the collector of gas flows with an increased helium content, an inlet for a refrigerant flow and an outlet for a refrigerant flow;

[0044] - a collector of gas flows with an increased helium content, which contains an inlet of a nitrogen-helium mixture flow, an inlet of a vapor-liquid flow with an increased helium content and an outlet of a vapor-liquid flow saturated with helium, connected to the inlet of the still of the condensation column for helium extraction through a valve.

[0045] Moreover, the installation may also additionally include:

[0046] - a helium-free raw gas compression unit comprising an inlet of a low-pressure helium-free raw gas stream from a high-temperature heat exchanger, wherein the outlet of the stream from the compression unit is connected to the inlet of a helium-free raw gas stream collector;

[0047] - a helium-free feed gas manifold comprising an inlet of helium-free feed gas from the helium-free feed gas compression unit, an inlet of high-pressure helium-free feed gas, and an outlet of the feed gas from the manifold, which also serves as the gas outlet of the unit. Liquid nitrogen may be used as a refrigerant in the unit.

[0048] The installation may also additionally include:

[0049] - a liquid nitrogen feed separator comprising a liquid nitrogen inlet, which is the inlet of the liquid nitrogen flow into the unit, a liquid outlet connected to the inlet of the condenser of the helium extraction condensation column, and a gas outlet connected to one of the inlets of the nitrogen flow collector;

[0050] - a nitrogen flow collector that contains an inlet for a flow of gaseous nitrogen from a liquid nitrogen separator, an inlet for a flow of nitrogen from a column condenser, and an outlet for a flow of nitrogen, which is the outlet of the flow of nitrogen from the unit.

[0051] The installation may also additionally include a heat exchanger installed on the nitrogen discharge line, containing an inlet for a nitrogen flow from a nitrogen flow collector, and an outlet for a nitrogen flow, which is the outlet of the flow from the installation.

[0052] Moreover, the installation may additionally include:

[0053] - a liquid nitrogen feed separator, which contains a liquid nitrogen inlet, which is the inlet of the liquid nitrogen flow into the unit, a liquid outlet connected to the inlet of the condenser of the helium extraction condensation column, and a gas outlet connected to one of the inlets of the nitrogen flow collector;

[0054] - a nitrogen flow collector that contains an inlet for a flow of gaseous nitrogen from a liquid nitrogen separator, an inlet for a flow of nitrogen from a column condenser, and an outlet for a flow of nitrogen connected to the inlet for a flow of nitrogen into a heat exchange apparatus for cooling a nitrogen-helium mixture.

[0055] The installation may also additionally include a heat exchange apparatus installed on the nitrogen discharge line, which contains an inlet for the nitrogen flow from the heat exchange apparatus for cooling the nitrogen-helium mixture flow and an outlet for the nitrogen flow, which is the outlet of the flow from the installation.

[0056] Moreover, the installation may also additionally include a nitrogen-helium mixture compression unit installed on the nitrogen-helium mixture supply line, which contains an input of the nitrogen-helium mixture flow, which is the input of the flow into the installation, and an output of the nitrogen-helium mixture flow, which is connected to the input of the heat exchange apparatus for cooling the nitrogen-helium mixture.

[0057] Description of drawings.

[0058] Fig. 1. - General diagram of the system for extracting helium concentrate from the gasifier.

[0059] Fig. 2. - General diagram of the system for extracting helium concentrate from the gasifier with a supply line for the recirculation flow of the nitrogen-helium mixture.

[0060] Fig. 3. - General diagram of the system for extracting helium concentrate from the gasification system with a supply line for the recirculation flow of the nitrogen-helium mixture and cooling with liquid nitrogen.

[0061] The following positions are indicated on the presented drawings:

[0062] 1 - high-temperature heat exchanger; 2 - medium-temperature heat exchanger; 3 - low-temperature heat exchanger; 4 - heavy components absorber; 5 - helium extraction stripping column; 6 - non-condensable components separator; 7 - helium extraction condensation column; 8 - condenser of the helium extraction condensation column; 9 - separator of the helium extraction condensation column; 10 - heat exchanger for cooling the nitrogen-helium mixture; 11 - liquid nitrogen separator; 12 - heat exchanger for heating the nitrogen stream; 13 - helium-free feed gas stream compression unit; 14 - nitrogen-helium mixture stream compression unit; 15 - feed stream distribution manifold; 16 - low-pressure helium-free gas stream collector; 17 - gas stream collector with increased helium content; 18 - nitrogen stream collector; 19 - collector of gas flows saturated with helium and a flow of nitrogen-helium mixture; 20 - collector of gas flows without high-pressure helium.

[0063] Designations: A - raw gas; B - raw gas without high-pressure helium; B - raw gas without low-pressure helium; G - helium concentrate; D - refrigerant; E - nitrogen-helium mixture, G - liquid nitrogen, Z - gaseous nitrogen.

[0064] The plant for extracting helium concentrate from the liquefied gas (SG) shown in Fig. 1 comprises a high-temperature heat exchanger 1, a heavy component absorber 4, a medium-temperature heat exchanger 2, a separator of non-condensable components 6, a helium extraction stripping column 5, a low-temperature heat exchanger 3, a helium extraction condensation column 7, a condenser of the helium extraction condensation column 8, and a separator of the helium extraction condensation column 9, all connected by pipelines. The plant also includes a feed stream distribution manifold 15, the gas inlet of which is also the SG inlet of the plant. One of the manifold outlets is connected to the SG flow inlet of the high-temperature heat exchanger 1, and the other manifold outlet is connected to the inlet of the feed helium-containing gas flow into the still of the heavy component absorber 4.

[0065] The high-temperature heat exchanger 1 includes an inlet for the SOG stream, the outlet of which is connected via a valve to the inlet at the top of the heavy component absorber 4, the inlet for the first return stream is connected via a valve to the outlet of the bottom liquid stream of the heavy component absorber 4, wherein the outlet of the first return stream is the outlet of the feed gas stream without high-pressure helium from the unit. The high-temperature heat exchanger 1 also includes an inlet for the second return stream from the feed gas stream collector without low-pressure helium, wherein the outlet of the stream is the outlet of the feed gas stream without low-pressure helium from the unit. The high-temperature heat exchanger 1 also includes an inlet and outlet for the third return stream, which is a stream of helium concentrate, wherein the outlet of the helium concentrate stream from the heat exchanger 1 is also the outlet of the main production stream from the unit.

[0066] The absorber 4 of heavy components is connected by the inlet of the cooled raw gas flow SOG in the upper part of the absorber through a valve to the outlet of the direct flow of the high-temperature heat exchanger 1, the inlet of the raw gas flow SOG through a valve to the distribution manifold of the raw gas flow SOG 15, the outlet of the bottom liquid, which is a flow of raw gas without high-pressure helium, through a valve to the inlet of the first return flow into the high-temperature heat exchanger 1.

[0067] The medium-temperature heat exchanger 2 is connected by a direct flow inlet to the outlet of a gas flow saturated with helium from the absorber 4. The collector of low-pressure helium-free gas flows 16 contains an inlet of the first reverse gas flow from the medium-temperature heat exchanger 2, an inlet of the second gas flow from the medium-temperature heat exchanger 2 and an outlet of the gas flow from the collector, connected to the inlet of the second flow into the high-temperature heat exchanger 1.

[0068] The stripping column for helium extraction 5 is connected by the outlet of the first part of the bottom liquid flow of the stripping column through a valve to the inlet of the medium-temperature heat exchanger 2, which performs the function of a reboiler of the stripping column 5, the inlet of the first part of the bottom liquid flow - to the outlet of the medium-temperature heat exchanger 2, and the outlet of the second part of the bottom liquid flow through a valve - to the inlet of the first return flow of raw gas without low-pressure helium of the medium-temperature heat exchanger 2.

[0069] The inlet of the separator of non-condensable components 6 is connected to the outlet of the vapor-liquid flow saturated with helium from the medium-temperature heat exchanger 2, and the liquid outlet is connected to the inlet to the upper part of the stripping column for helium extraction 5.

[0070] The collector of gas flows with increased helium content 17 contains an inlet of a gas flow with increased helium content from the separator of non-condensable components 6, an inlet of a gas flow with increased helium content from the helium extraction stripping column 5 and an outlet of a gas flow from the collector, connected to the inlet of the low-temperature heat exchanger 3.

[0071] The low-temperature heat exchange apparatus 3 contains an inlet of a gas flow with an increased helium content from the collector 17, an outlet of a vapor-liquid flow with an increased helium content, connected to the bottom of the condensation column for helium extraction 7 through a valve, and an outlet of the first return flow, connected to the inlet of the second return flow into the medium-temperature heat exchange apparatus 2 through a valve.

[0072] The condensation column for helium extraction 7 is connected by an inlet in the bottom part of the flow saturated with helium to the outlet of the direct flow of the low-temperature heat exchanger 3, by the outlet of the gas flow it is connected to the inlet of the condenser 8 of the column 7, and by the outlet of the bottom liquid it is connected to the inlet of the first return flow of the low-temperature heat exchanger 3 through a valve, wherein the outlet of the bottom liquid from the first return flow of the low-temperature heat exchanger is connected to the inlet of the second return flow of the medium-temperature heat exchanger 2 through a valve, the outlet of which is connected to the inlet of the second return flow of the high-temperature heat exchanger 1, the outlet of which is the outlet from the raw gas unit without low-pressure helium.

[0073] The condenser 8 of the condensation column for extracting helium 7 contains an inlet of a gas stream from the column 7, an outlet of a stream connected to the inlet of the separator 9 of the column 7, an inlet of a refrigerant stream and an outlet of a refrigerant stream.

[0074] The separator 9 of the condensation column for extracting helium 7 contains an input of the vapor-liquid flow from the condenser 8 of the column 7, an output of the liquid flow connected to the input in the upper part of the column 7, an output of the helium concentrate flow connected to the input of the second return flow into the low-temperature heat exchanger 3 through a valve.

[0075] The outlet of the second return flow of helium concentrate from the low-temperature heat exchanger 3 is connected to the inlet of the third return flow of the medium-temperature heat exchanger 2 through a valve, the outlet of which is connected to the inlet of the third return flow of the high-temperature heat exchanger 1, the outlet of the flow of helium concentrate from which is the outlet of the main production flow from the installation.

[0076] The proposed installation, in a particular case of implementation, shown in Fig. 2, additionally contains a heat exchange apparatus for cooling the nitrogen-helium mixture 10.

[0077] The proposed installation, in the particular case of implementation shown in Fig. 3, additionally contains a liquid nitrogen separator 11, a heat exchange apparatus for heating a nitrogen stream 12, a unit for compressing raw gas without helium 13, a unit for compressing a nitrogen-helium mixture stream 14 and a collector of gas streams without high pressure helium 20. The liquid nitrogen separator 11 contains an inlet of a nitrogen stream, which is the inlet of a stream into the installation, an outlet of a liquid nitrogen stream connected to the inlet of the condenser 8 of the condensation column 7, and an outlet of a gaseous nitrogen stream, which is connected to the inlet of the heat exchange apparatus for cooling the nitrogen-helium mixture 10 through the nitrogen stream collector 18. The heat exchange apparatus for heating the nitrogen stream 12 contains an inlet of a nitrogen stream from the heat exchange apparatus for cooling the nitrogen-helium mixture 10 and an outlet of a nitrogen stream, which is the outlet of a stream from the installation.The helium-free raw gas compression unit 13 comprises an inlet for a low-pressure helium-free raw gas stream from the high-temperature heat exchanger 1 and a gas stream outlet connected to the outlet of the high-pressure helium-free gas stream collector 20. The high-pressure helium-free gas stream collector 20 also comprises an inlet for a high-pressure helium-free stream from the heavy component absorber 4 and an outlet for a high-pressure helium-free gas stream from the unit. The inlet to the unit of the nitrogen-helium mixture stream directed from the pure helium production unit is the inlet of the nitrogen-helium mixture stream into the nitrogen-helium mixture compression unit 14, which comprises an inlet for the nitrogen-helium mixture stream and an outlet connected to the inlet of the nitrogen-helium mixture cooling heat exchanger 10.The heat exchange apparatus for cooling the nitrogen-helium mixture 10 contains an inlet for the nitrogen-helium mixture flow, the outlet from the heat exchange cooling apparatus is connected to one of the inlets of the collector of gas flows saturated with helium and the flow of the nitrogen-helium mixture 19. In this case, the heat exchange apparatus 10 is provided with an inlet for the nitrogen flow and an outlet for the nitrogen flow, connected to the inlet of the heat exchange apparatus for heating the nitrogen flow 12. The outlet from the collector 19 is connected to the bottom of the condensation column for extracting helium.

[0078] To describe the method and operation of the installation, examples of the invention are presented.

[0079] Example 1

[0080] The installation for extracting helium concentrate from the SOG, shown in Fig. 1, operated as follows.

[0081] The feed stream of SOG with a low H2 content (less than 50% mol) and a low N2 content (less than 70% mol), containing CH , Cr+ and He hydrocarbons, at a pressure of 2.60-2.74 MPa (abs.) was fed to the helium concentrate extraction unit, where it was divided into two parts in the feed stream distribution manifold 15. In this case, part of the stream was cooled and condensed in the high-temperature heat exchanger 1, then the vapor-liquid stream of SOG was throttled and fed over the packing into the upper part of the absorber 4 of heavy components, the other part of the initial feed stream was throttled and fed to the bottom of the absorber 4. The bottom liquid stream of the absorber 4 with a low helium content was throttled, heated in the high-temperature heat exchanger 1 and removed from the unit.During heat and mass transfer in the packed section of absorber 4, the vapor stream was enriched primarily in helium, then withdrawn from the upper section of absorber 4, cooled, and condensed in medium-temperature heat exchanger 2. The vapor-liquid stream was directed to separator 6 for non-condensable components. The liquid stream from the separator was throttled and fed over the packing to stripper column 5 for helium recovery. A portion of the stripper liquid stream was directed for heating to medium-temperature heat exchanger 2, which served as a reboiler for column 5, with the flow moving according to the thermosyphon principle. During the heat and mass transfer process, the steam flow in column 5 was saturated with helium, then the gas flow was taken from the top of the column and mixed with the steam flow from the separator of non-condensable components 6. The flow of bottom liquid from the stripping column 5, saturated with methane, was removed from the bottom, throttled and fed for heating to the medium-temperature heat exchanger 2.The gas stream with an increased helium content, obtained during the mixing of the gas streams from separator 6 and column 5 in collector 17, was cooled in low-temperature heat exchanger 3, throttled, and fed to condensation column 7 for helium recovery, where, during heat and mass transfer in the packed section of the column, the vapor stream was saturated with helium, while the liquid stream was saturated primarily with nitrogen and methane. In condenser 8 of column 7, as a result of heat exchange with the refrigerant stream, partial condensation of the helium-saturated stream occurred. Separation of the vapor-liquid stream then occurred in separator 9 of column 7, with the helium concentrate being removed as a vapor phase from separator 9, and the liquid from separator 9 being fed to the column for reflux.

[0082] The gaseous stream of helium concentrate from separator 9 of condensation column 7 was successively heated in low-temperature 3, medium-temperature 2, and high-temperature 1 heat exchangers. The stream of bottom liquid from condensation column 7, which contained predominantly nitrogen and methane, was throttled, heated in low-temperature 3 and medium-temperature 2 heat exchangers, mixed with the stream from the bottom of stripping column 5, heated in high-temperature heat exchanger 1, and withdrawn from the unit.

[0083] As a result of the process, low-temperature gas separation was achieved at pressures less than 3.0 MPa (abs.), while the extraction coefficient for the target product was achieved to be more than 0.97, without the use of complex dynamic equipment in the technological process.

[0084] Example 2

[0085] A setup for extracting helium concentrate from a decomposed gas condensate (DGC) was assembled, as shown in Fig. 2. The process was carried out similarly to Example 1, with the difference that a stream of nitrogen-helium mixture at a pressure of 2.10 MPa (abs.) was additionally fed to the setup inlet, after which it was fed for cooling to a nitrogen-helium mixture cooling heat exchanger 10, in which the stream was cooled by a nitrogen stream. The stream was then mixed with a helium-saturated vapor-liquid stream from a low-temperature heat exchanger 3.

[0086] As a result of the process, low-temperature gas separation was achieved at pressures less than 3.0 MPa (abs.), while the extraction coefficient for the target product was achieved to be more than 0.97, without the use of complex dynamic equipment in the technological process.

[0087] Example 3

[0088] A unit for extracting helium concentrate from the SOG was installed, shown in Fig. 3.

[0089] The feed stream of SOG with a pressure of 2.74 MPa (abs.), with a helium content of 0.33 mol., was fed to the inlet of the helium concentrate extraction unit, where it was divided into two parts. In this case, part of the stream was cooled and condensed in the high-temperature heat exchanger 1 , then the vapor-liquid stream of SOG was throttled and fed over the packing into the upper part of the absorber 4 of heavy components, the other part of the initial feed stream was throttled and fed to the bottom of the absorber 4. The bottom liquid stream with a low helium content was throttled, heated in the high-temperature heat exchanger 1 , mixed with the gas stream in the high-pressure helium-free gas stream collector 20 and removed from the unit. Due to heat and mass transfer processes in the packed part of the column, the vapor stream was enriched mainly in helium. The vapor stream with a helium content of 1.56 mol.The liquid was withdrawn from the top of the column, cooled, and condensed in medium-temperature heat exchanger 2. The vapor-liquid flow was then directed to separator 6 for non-condensable components. The liquid flow from separator 6 was throttled and fed over packing into stripping column 5 for helium recovery. A portion of the liquid flow from column 5 was directed for heating to the stripping column's medium-temperature heat exchanger-reboiler, with the flow moving according to the thermosyphon principle. During the heat and mass transfer process, the steam flow in stripping column 5 was saturated with helium, then the gas flow was taken from the top of the column and mixed with the steam flow from separator 6. The flow of bottom liquid, saturated with methane, was removed from the bottom of the stripping column, throttled and fed for heating to the medium-temperature heat exchanger 2. The gas flow with an increased helium content, obtained during the mixing of gas flows from separator 6 and column 5 in collector 17, with a helium content of 21.68 mol%., was cooled in low-temperature heat exchanger 3. The flow of nitrogen-helium mixture, supplied to the unit with a pressure of 0.12 MPa (abs.) and a helium content of 48.27% mol., was supplied for compression to the nitrogen-helium mixture compression unit 14 to a pressure of 2.10 MPa (abs.), then cooled in the heat exchanger for cooling the nitrogen-helium mixture 10 and mixed with the gas flow enriched with helium from the low-temperature heat exchanger 3. The flow of the mixture with a helium content of 24.33% mol. was supplied to the condensation column for helium extraction 7, where, during the process of heat and mass transfer in the packed section, the saturation of the vapor flow with helium occurred, while the liquid flow was saturated mainly with nitrogen and methane. In the condenser 8 of the column 7, as a result of heat exchange with the liquid nitrogen flow, partial condensation occurred in the concentrate flow, then in the separator 9 of the column 7, the phases of the vapor-liquid flow were separated, while the helium concentrate with a pressure of 1.9 MPa (abs.) and a helium content of 75.94% mol. was removed as a vapor phase from separator 9, liquid from separator 9 was fed to reflux the column. A stream of liquid nitrogen was fed to the condenser 8 of the column to ensure the calculated operating mode; during heat exchange in the condenser, the nitrogen stream evaporated, after which it was directed to the heat exchanger for cooling the nitrogen-helium mixture 10, after which it was heated in the heat exchanger for heating the nitrogen 12 and removed from the unit. The gaseous stream of helium concentrate was sequentially heated in low-temperature 3, medium-temperature 2 and high-temperature 1 heat exchangers, after which it was removed from the unit.The flow of the bottom liquid of the condensation column, which contained predominantly nitrogen and methane, was throttled, heated in the low-temperature 3 and medium-temperature 2 heat exchangers, mixed with the flow from the bottom of the stripping column 5, then heated in the high-temperature heat exchanger 1, compressed in the raw gas compression unit without helium 13, mixed with the flow from the bottom of the absorber 4 of heavy components in the collector of gas flows without high pressure helium 20 and removed from the unit.

[0090] As a result of the process, low-temperature gas separation was achieved at pressures less than 3.0 MPa (abs.), while the extraction coefficient for the target product was achieved to be more than 0.97, without the use of complex dynamic equipment in the technological process.

[0091] Experiments have shown that the extraction process can be achieved for gas compositions with different contents of methane, helium and hydrogen.

Claims

CLAUSES OF THE INVENTION 1. A method for extracting helium concentrate from dry stripped gas, which consists in that the initial feed stream of dry stripped gas (DSG) containing methane, C2+ hydrocarbons, nitrogen in an amount of less than 70% by mole, helium and hydrogen in an amount of less than 50% by mole, is fed to a helium concentrate extraction unit, divided into two parts, one of which is cooled and condensed in a high-temperature heat exchanger, then throttled and fed to an absorber of heavy components for separation, and the other part of the initial feed stream is throttled and fed to the bottom of the absorber of heavy components, in which the flow of bottom liquid with a low helium content is throttled and heated in a high-temperature heat exchanger, after which it is withdrawn as a feed gas flow without helium, and the flow of vapor saturated with helium is taken from the upper part of the said absorber, cooled and condensed in a medium-temperature heat exchanger device,after which the vapor-liquid stream is directed to a separator of non-condensable components, the liquid stream from which is throttled and fed for separation to a stripping column for helium extraction, part of the liquid stream from which is directed for heating to a medium-temperature heat exchanger that functions as a reboiler for the column, and returned to the column, the bottom liquid stream is throttled and fed for heating to the medium-temperature heat exchanger, the vapor stream saturated with helium is withdrawn from the stripping column, mixed with the vapor stream from the separator of non-condensable components, then cooled and partially condensed in a low-temperature heat exchanger, the cooled vapor-liquid stream is fed to a condensation column for helium extraction, including a condenser, into which a refrigerant stream is fed for cooling and partially condensing the gas stream at the top of the condensation column,wherein the gas flow in the upper part of the column is cooled and partially condensed in the column condenser as a result of heat exchange with the refrigerant flow, then fed to the column separator for phase separation, the liquid flow from the column separator is fed to reflux the column, and the vapor flow from the column separator, which is helium concentrate, is removed from the separator and sequentially heated in low-temperature, medium-temperature, and high-temperature heat exchange apparatuses, the flow of the bottom liquid of the condensation column for helium extraction is throttled, successively heated in low-temperature and medium-temperature heat exchange apparatuses, mixed with the heated flow from the bottom of the stripping column, heated in a high-temperature heat exchange apparatus and the flow after heating is removed as a flow of raw gas without helium.

2. The method according to paragraph 1, characterized in that an additional flow of nitrogen-helium mixture is supplied, which is cooled in a heat exchange apparatus for cooling the nitrogen-helium mixture and mixed with a flow of gas from a low-temperature heat exchange apparatus.

3. The method according to paragraph 1 or 2, characterized in that the low-pressure helium-free raw gas streams from the stripping column and the helium recovery condensation column, after heating in a high-temperature heat exchanger, are fed for compression to a helium-free raw gas compression unit and mixed with a high-pressure helium-free raw gas stream from the heavy component absorber, after which the stream is removed from the unit.

4. The method according to paragraph 2, characterized in that the flow of nitrogen-helium mixture is fed for compression into the nitrogen-helium mixture compression unit before the temperature of the flow is lowered in the heat exchange apparatus for cooling the nitrogen-helium mixture.

5. The method according to any one of paragraphs 1-4, characterized in that the condenser of the condensation column is cooled with a stream of liquid nitrogen.

6. The method according to any of paragraphs 2-4, characterized in that a stream of liquid nitrogen is supplied as a coolant, which is used to cool the condenser of the condensation column.

7. The method according to paragraph 6, characterized in that the flow of liquid nitrogen after the condenser is used to cool the heat exchange apparatus for cooling the nitrogen-helium mixture.

8. The method according to paragraph 6 or 7, characterized in that the flow of liquid nitrogen is throttled to form a vapor-liquid flow, which is fed for separation into a liquid nitrogen separator, the flow of liquid nitrogen from the separator is fed into the condenser of the column, after which it is mixed with a flow of gaseous nitrogen from the liquid nitrogen separator and fed to cool the flow of nitrogen-helium mixture in a heat exchange apparatus for cooling the nitrogen-helium mixture.

9. The method according to paragraph 8, characterized in that the nitrogen flow after heating in the heat exchange apparatus for cooling the nitrogen-helium mixture is heated in the heat exchange apparatus and removed from the installation.

10. An installation for extracting helium concentrate from dry stripped gas, comprising: - a collector for distributing the raw flow of SOG containing methane, C2+ hydrocarbons, nitrogen in an amount of less than 70% by mole, helium and hydrogen in an amount of less than 50% by mole, the inlet of which is also the inlet of SOG into the unit; - a high-temperature heat exchanger connected via a forward flow inlet to the feedstock flow distribution manifold; a heavy component absorber connected via a forward flow inlet of the cooled SOG feedstock flow at the top of the absorber via a valve to the forward flow outlet of the high-temperature heat exchanger, via a valve to the SOG feedstock flow distribution manifold, via a valve to the bottom liquid outlet, which is a helium-free feedstock gas flow, to the first reverse flow inlet of the high-temperature heat exchanger; a medium-temperature heat exchanger connected via a forward flow inlet to the outlet of the helium-saturated gas flow from the absorber; - a collector of gas flows without low-pressure helium, comprising an inlet of the first return gas flow from the medium-temperature heat exchanger, an inlet of the second gas flow from the medium-temperature heat exchanger and an outlet of the gas flow from the collector, connected to the inlet of the second flow into the high-temperature heat exchanger; - a helium recovery stripping column, which is connected by the outlet of the first part of the bottoms liquid flow of the stripping column through a valve to the inlet of a medium-temperature heat exchanger that functions as a reboiler of the stripping column, the inlet of the first part of the bottoms liquid flow to the outlet of the medium-temperature heat exchanger, and the outlet of the second part of the bottoms liquid flow through a valve to the inlet of the first return flow of raw gas without low-pressure helium of the medium-temperature heat exchanger; - a separator of non-condensable components, the inlet of which is connected to the outlet of the vapor-liquid flow saturated with helium from the medium-temperature heat exchanger, and the liquid outlet is connected to the inlet to the upper part of the helium extraction stripping column; - a collector of gas flows with an increased helium content, comprising an inlet of a gas flow with an increased helium content from a separator of non-condensable components, an inlet of a gas flow with an increased helium content from a helium extraction stripping column and an outlet of a gas flow from the collector, connected to the inlet of a low-temperature heat exchanger; - a low-temperature heat exchange apparatus, which contains an inlet of a gas flow with an increased helium content from a collector, an outlet of a vapor-liquid gas flow with an increased helium content, connected to the bottom of a condensation column for extracting helium through a valve, and an outlet of a first return flow, connected to the inlet of a second return flow into a medium-temperature heat exchange apparatus through a valve; - a condensation column for helium extraction, which is connected by the inlet of the bottoms portion of the helium-saturated stream to the outlet of the direct stream of the low-temperature heat exchanger, by the outlet of the vapor-liquid gas stream is connected to the inlet of the column condenser, and by the outlet of the bottoms liquid is connected to the inlet of the first return stream of the low-temperature heat exchanger through a valve, wherein the outlet of the bottoms liquid from the first return stream of the low-temperature heat exchanger is connected to the inlet of the second return stream of the medium-temperature heat exchanger through a valve, the outlet of which is connected to the inlet of the second return stream of the high-temperature heat exchanger, the outlet of which is the outlet of the raw gas unit without low-pressure helium; - a condenser of the condensation column for helium extraction, which contains an inlet of the gas stream from the condensation column, an outlet of the stream connected to the inlet of the separator of the condensation column for helium extraction, an inlet of the refrigerant stream and an outlet of the refrigerant stream; - a condensation column separator that contains an inlet for the vapor-liquid flow from the column condenser; a liquid flow outlet connected to the inlet at the top of the condensation column columns, an outlet of a helium concentrate flow connected to the inlet of a second return flow into a low-temperature heat exchanger through a valve; wherein the outlet of the second return flow of helium concentrate from the low-temperature heat exchanger is connected to the inlet of a third return flow of a medium-temperature heat exchanger through a valve, the outlet of which is connected to the inlet of a third return flow of a high-temperature heat exchanger, the outlet of the helium concentrate flow from which is the outlet of the main production flow from the unit.

11. The installation according to paragraph 10, characterized in that it additionally includes: - a heat exchange apparatus for cooling a nitrogen-helium mixture, which contains an inlet for a nitrogen-helium mixture flow, which is the inlet for the nitrogen-helium mixture flow into the unit, a flow outlet connected to the inlet into the collector of gas flows with an increased helium content, an inlet for a refrigerant flow and an outlet for a refrigerant flow; - a collector of gas flows with an increased helium content, which contains an inlet of a nitrogen-helium mixture flow, an inlet of a vapor-liquid flow with an increased helium content and an outlet of a vapor-liquid flow saturated with helium, connected to the inlet of the still of the condensation column for helium extraction through a valve.

12. The installation according to paragraph 10 or 11, characterized in that it additionally includes: - a helium-free raw gas compression unit comprising an inlet of a low-pressure helium-free raw gas stream from a high-temperature heat exchanger, wherein the outlet of the stream from the compression unit is connected to the inlet of a helium-free raw gas stream collector; - a helium-free raw gas manifold comprising an inlet of a helium-free raw gas stream from a helium-free raw gas compression unit, an inlet of a high-pressure helium-free raw gas stream, and an outlet of a raw gas stream from the manifold, which is also the outlet of the gas stream from the plant.

13. An installation according to any of paragraphs 10-12, characterized in that liquid nitrogen is used as a coolant.

14. The installation according to paragraph 13, characterized in that it additionally includes: - a liquid nitrogen feed separator comprising a liquid nitrogen inlet, which is the inlet of the liquid nitrogen flow into the unit, a liquid outlet connected to the inlet of the condenser of the helium extraction condensation column, and a gas outlet connected to one of the inlets of the nitrogen flow collector; - a nitrogen flow collector that contains an inlet for a flow of gaseous nitrogen from a liquid nitrogen separator, an inlet for a flow of nitrogen from a column condenser, and an outlet for a flow of nitrogen, which is the outlet of the flow of nitrogen from the unit.

15. The installation according to paragraph 14, characterized in that it additionally includes a heat exchanger installed on the nitrogen discharge line, containing an inlet for a nitrogen flow from a nitrogen flow collector, and an outlet for a nitrogen flow, which is the outlet of the flow from the installation.

16. The installation according to paragraph 13, characterized in that it additionally includes: - a liquid nitrogen feed separator, which contains a liquid nitrogen inlet, which is the inlet of the liquid nitrogen flow into the unit, a liquid outlet connected to the inlet of the condenser of the helium extraction condensation column, and a gas outlet connected to one of the inlets of the nitrogen flow collector; - a nitrogen flow collector that contains an inlet for a flow of gaseous nitrogen from a liquid nitrogen separator, an inlet for a flow of nitrogen from a column condenser, and an outlet for a flow of nitrogen connected to the inlet for a flow of nitrogen into a heat exchange apparatus for cooling a nitrogen-helium mixture.

17. The installation according to paragraph 16, characterized in that it additionally includes a heat exchange apparatus installed on the nitrogen discharge line, which contains an inlet for the nitrogen flow from the heat exchange apparatus for cooling the nitrogen-helium mixture flow and an outlet for the nitrogen flow, which is the outlet of the flow from the installation.

18. The installation according to one of paragraphs 11, 16 or 17, characterized in that it additionally includes a nitrogen-helium mixture compression unit installed on the nitrogen-helium mixture supply line, which contains an inlet for the nitrogen-helium mixture flow, which is the inlet of the flow into the installation, and an outlet for the nitrogen-helium mixture flow, which is connected to the inlet of the heat exchange apparatus for cooling the nitrogen-helium mixture.

Images