Method for purifying natural gas of acidic fractions (variants)

Abstract

The invention relates to the field of purifying natural gas of acidic fractions. The invention can be used for removing hydrogen sulphide and carbon dioxide from natural gas. The proposed method for purifying natural gas of acidic fractions includes the following steps: introducing a feed stream of natural gas into a mass transfer column in which the gas feed stream is separated into a gas depleted of acidic fractions, which is withdrawn from the top of the column, and a liquid rich in acidic fractions, which is withdrawn from the bottom of the mass transfer column; heating the acidic fraction-depleted gas withdrawn from the top of the column in at least one heat exchanger and subsequently compressing the gas in a compressor, then cooling the gas in a cooling apparatus and the heat exchanger, expanding the gas and introducing the resulting two-phase flow into the top part of the mass transfer column; wherein the flow rate of the compressor is selected so that the flow rate of the gas therethrough is at least 1.7 times greater than the flow rate of the natural gas feed stream.

Description

[0001] METHOD FOR PURIFYING ACIDIC FRACTIONS FROM NATURAL GAS (OPTIONS)

[0002] The present invention relates to a method for purifying natural gas from acidic fractions. The invention can be used to remove hydrogen sulfide and carbon dioxide from natural gas.

[0003] In the processing of commercial natural gas, for example, due to requirements for the resulting commercial natural gas, it is necessary to remove hydrogen sulfide and carbon dioxide from the natural gas. Standard technical requirements for LNG often include a requirement for a hydrogen sulfide content of 7 ppm in commercial natural gas, and when preparing natural gas for liquefaction, the carbon dioxide content in the gas must be 50 ppm. Requirements for CO2 concentration in LNG are due to the risk of CO2 crystal formation during the liquefaction of natural gas. The required low concentration of hydrogen sulfide in commercial natural gas is due to the extreme toxicity of hydrogen sulfide to humans.

[0004] The closest to the claimed invention is a method for processing natural gas containing nitrogen, known from US Patent Application No. 2023076428, comprising the following steps: feeding an input natural gas stream into a distillation column, in which the input gas stream is liquefied and separated into a nitrogen-enriched gas taken from the top of the column and liquefied natural gas taken from the bottom of the column; heating the nitrogen-enriched gas taken from the top of the column in a heat exchanger, followed by compression, sequential cooling in an air cooler and a heat exchanger, expansion, and feeding the resulting two-phase stream to the top of the column. This method is used to separate nitrogen from natural gas.The disadvantage of the presented method is that nitrogen is removed during the liquefaction of natural gas, which uses cold that must be produced using special refrigeration cycles. This greatly complicates the entire gas processing plant and leads to high capital and operating costs.

[0005] Patent RU 2533260C2 also describes a method for purifying gas from acidic fractions by cooling the gas and treating the cooled gas with a solvent to reduce the concentration of acidic fractions. A disadvantage of this method is the use of expensive solvents, which increases the operating costs of the process.

[0006] The objective of the invention is to increase the efficiency of removing acidic fractions from natural gas while simultaneously reducing capital costs for producing commercial natural gas.

[0007] The technical result achieved in this way consists in simplifying the design of the installation for preparing natural gas to commercial condition.

[0008] BRIEF DESCRIPTION OF THE INVENTION

[0009] The proposed method for purifying natural gas from acidic fractions can be implemented in several ways.

[0010] In a first embodiment, the proposed method for purifying natural gas from acidic fractions includes the following stages: feeding an input natural gas stream into a mass-exchange column, in which the input gas stream is separated into a gas depleted in acidic fractions, taken from the top of the column, and a liquid enriched in acidic fractions, taken from the bottom of the mass-exchange column; heating the gas depleted in acidic fractions, taken from the top of the column, in at least one heat exchanger, followed by its compression in a compressor, sequential cooling in a cooling apparatus and a heat exchanger, expansion and feeding the resulting two-phase stream to the top of the mass-exchange column; wherein the capacity of the compressor is selected such that the gas flow through it is at least 1.7 times greater than the flow rate of the input natural gas stream.

[0011] In a second embodiment, the proposed method for purifying natural gas from acidic fractions, containing acidic fractions, includes the following stages: feeding an input natural gas stream into a separator or mass-exchange column, collecting the gas phase from the top of the separator or mass-exchange column and the liquid and / or crystalline phase from the bottom of the separator or mass-exchange column; feeding the gas phase from the top of the separator or mass-exchange column into an additional separator or an additional mass-exchange column, collecting gas depleted in acidic fractions from the top of the column and liquid enriched in acidic fractions from the bottom of the additional separator or an additional mass-exchange column, heating the gas depleted in acidic fractions, collected from the top of the additional separator or an additional mass-exchange column, in at least one heat exchanger, followed by compression in a compressor, sequential cooling in a cooling apparatus and a heat exchanger,expanding and separating the resulting two-phase flow into a first and second portion, feeding the first portion of the resulting two-phase flow into a mass-transfer column or separator, and feeding the second portion of the resulting two-phase flow into an additional mass-transfer column or separator, wherein the compressor capacity is selected such that the gas flow rate through it is at least 1.7 times greater than the flow rate of the incoming natural gas. In all embodiments of the proposed methods, it is possible to recover a portion of the gas depleted in acid fractions at any stage of processing the gas depleted in acid fractions.

[0012] The inlet natural gas stream is processed to remove moisture, mercury, and heavy hydrocarbons from the natural gas before being fed to the mass transfer column or separator.

[0013] In all three variants, expansion of the flow depleted in acidic fractions can be carried out in a throttle or turbine.

[0014] The liquid enriched in acidic fractions, collected from the bottom of the mass exchange column, can be subjected to further fractionation.

[0015] The liquid enriched in acidic fractions, collected from the bottom of the mass exchange column (option 1), may contain solidified fractions of natural gas.

[0016] BRIEF DESCRIPTION OF THE FIGURES

[0017] Fig. 1 is a schematic diagram illustrating a method and system for purifying natural gas from acidic fractions in accordance with embodiment 1 of the present invention.

[0018] Fig. 2 is a schematic diagram illustrating a method and system for purifying natural gas from acidic fractions in accordance with embodiment 2 of the present invention.

[0019] Fig. 3 is an enlarged schematic diagram illustrating a method and system for purifying natural gas from acid fractions in accordance with the present invention.

[0020] List of designations:

[0021] 1 - input natural gas,

[0022] 2-gas depleted in acid fractions, taken from the top of the column or separator,

[0023] 3 - gas flow entering the compressor inlet, 4 - mass transfer column or separator,

[0024] 5 - the flow that has been cooled in the cooling apparatus,

[0025] 6-stream entering the input of the expansion device,

[0026] 7- two-phase flow,

[0027] 8 - liquid enriched with acidic fractions,

[0028] 9 mixing device,

[0029] 10 - the selected portion of gas depleted in acid fractions,

[0030] 11 - liquid and / or crystalline phase collected from the bottom of the separator or mass transfer column,

[0031] 12 - gas expansion device,

[0032] 13 compressor,

[0033] 14 cooling apparatus,

[0034] 15 - heat exchanger,

[0035] 1 b - additional mass exchange column or separator,

[0036] 17 - gas phase from the top of the separator or mass transfer column,

[0037] 18 - the first part of the two-phase flow,

[0038] 19 - the second part of the two-phase flow,

[0039] 20 mixing and separation unit.

[0040] DETAILED DESCRIPTION OF THE INVENTION

[0041] Unless otherwise expressly stated herein, the singular form of a noun means one or more with respect to any feature in the embodiments of the present invention described in the specification and claims. Use of the singular form does not limit the meaning to a single feature unless such a limitation is expressly stated in the text.

[0042] As used herein, the term "natural gas feed stream" further includes gases and streams containing synthetic and / or natural gas substitutes, as well as natural gas recycle streams, such as, for example, a stream containing or consisting of boil-off gas from a hydrocarbon liquid storage tank. The primary component of natural gas is methane, and the natural gas feed stream typically contains at least 50% methane (molecular concentration). Other typical components of the feed or raw natural gas, which may be present in the feed stream in smaller quantities, include other, heavier hydrocarbons (such as ethane, propane, butanes, pentanes, etc.), helium, hydrogen, carbon dioxide, hydrogen sulfide and / or other gases, and mercury.However, the natural gas input stream may be pre-treated as necessary to reduce the (relative) levels of any high freeze point components, such as moisture, mercury, and / or heavier hydrocarbons, to levels necessary to prevent freezing or other operational problems in the natural gas sour fraction removal unit before being fed to the patented gas processing circuit.

[0043] A stream or gas is "sour ends lean" if the concentration of sour ends in the stream or gas is lower than the concentration of sour ends in the inlet natural gas stream.

[0044] As used in this document, the term "heat exchanger" refers to any device or system in which heat is exchanged between two or more streams. Unless otherwise expressly stated in the text, a heat exchanger may consist of one or more heat exchanger sections arranged in series and / or parallel, where a "heat exchanger section" is the portion of the heat exchanger in which heat is exchanged between two or more streams. Each such section may constitute a separate module with its own housing, but the sections may equally well be combined into a single heat exchanger module with a common housing. Unless otherwise expressly stated in the text, a heat exchanger may be of any suitable type, such as, but not limited to, a shell-and-tube, wound-wound, or plate-fin type heat exchanger.

[0045] The term "mass transfer column" refers to an apparatus (or group of apparatuses) containing one or more mass transfer sections, where each mass transfer section consists of one or more mass transfer stages (which may, but need not, contain inserts such as packing, trays, or mesh) that increase the contact area and thus improve mass transfer between the ascending vapor and the descending liquid flowing through the section within the apparatus. Thus, the concentration of lighter components (such as methane) increases toward the top of the column (and the concentration of acidic fractions decreases), while the concentration of heavier components (such as acidic fractions) increases toward the bottom of the column.

[0046] The term "expand" implies that the gas is expanded (the gas pressure is reduced). Expansion can occur either in a conventional throttle without performing any work or in a turbine with mechanical energy extracted from the turbine. The turbine can be either a turbogenerator, where the turbine shaft is connected to an electric generator, or a turboexpander unit, which contains a turbine and a compressor section. The compressor section can be included in the proposed gas processing scheme at any point, for example, before or after the compressor. In cases of low inlet gas flow rates, a piston expander can also be used for gas expansion.

[0047] Various other types of devices that reduce gas pressure can also be used to expand the gas, such as an ejector, a vortex tube, a supersonic separator, and other similar devices. The term "cooling unit" refers to any unit that cools a flow. This unit is often an air or water cooler, meaning that the gas is cooled by heating the surrounding air or pumped water. A special heat exchanger can also be used as a cooling unit, using any flow according to the proposed gas purification scheme or a special coolant (freon or other coolants) as the coolant.

[0048] The term "separator" refers to any unit that separates the gas phase from the liquid phase (or solid phase). The liquid phase may contain a solid phase, such as solidified components of natural gas such as heavy hydrocarbons, CO2, H2S, etc. Gas-liquid separators used in gas processing are divided according to their operating principle into the following main types: gravity, inertial, louver, centrifugal, mesh filter-separators, or combined separators. In-line separators, as well as separators with simultaneous flow expansion, such as supersonic separators, can also be used as separators. Separation of the liquid phase (or solid phase) can be carried out simultaneously with the recovery of a portion of the gas as a gas-liquid flow. A detailed description of the various types of separators is given in the book by Berlin M.A., Gorechenkov V.G., Volkov N.P. "Processing of oil and natural gases", Moscow, Chemistry, 1981 - 472 p.

[0049] The term "compressor" refers to any unit that increases gas pressure. The proposed methods for purifying natural gas may employ centrifugal, piston, or screw compressors, or a combination thereof. A detailed description of various compressor types is provided in the book "Processing of Oil and Natural Gases" by M.A. Berlin, V.G. Gorechenkov, and N.P. Volkov, Moscow: Khimiya, 1981, 472 pages. The term "mixing" refers to the mixing of streams. Mixing can occur simply by using a tee, into which, for example, two streams are fed, and at the outlet of the tee, the combined streams are withdrawn into a single pipeline. Mixing can also be accomplished using mixing devices, such as various types of mixers, such as ejectors, jet pumps, etc.Mixing can be accomplished by feeding the mixed streams into a unit or group of units in which the mixing process is combined with other processes, such as separation, fractionation, cooling or heating, expansion, compression, etc. In these cases, within the framework of the proposed methods for cleaning gas from acidic fractions, it is considered that the given unit or group of units performs the mixing process and falls under the term.

[0050] "mixing device".

[0051] The primary difference between the proposed invention and its prototype and similar products is that the flow rate of acid-depleted gas, withdrawn from the top of the mass-transfer column (or separator), is greater than the feed gas flow rate. In the proposed method for removing acid fractions from natural gas, the gas is purified within the column (or separator) by evaporating the liquid phase from a two-phase stream fed to the mass-transfer column (or separator). The two-phase stream is formed by heating the acid-depleted gas, withdrawn from the top of the mass-transfer column (or separator), in a heat exchanger, followed by compression in a compressor, cooling in a refrigeration unit and heat exchanger, and subsequent expansion.Inside the mass transfer column (or separator), the acid fractions, which primarily consist of carbon dioxide and hydrogen sulfide, are condensed by evaporating liquid methane (which constitutes the bulk of the two-phase flow fed to the mass transfer column (or separator). The primary condition for the successful organization of the proposed process is feeding a two-phase flow containing liquefied methane to the mass transfer column (or separator). In the proposed invention, a portion of the gas depleted in acid fractions, withdrawn from the mass transfer column, is used as the two-phase flow fed to the mass transfer column (or separator). The following sequence of operations is used to form the two-phase flow: heating the gas depleted in acid fractions, withdrawn from the mass transfer column (or separator) in a heat exchanger, followed by compression in a compressor, cooling in a cooling apparatus and a heat exchanger, and expansion.

[0052] The necessary conditions for the formation of a two-phase flow are ensured by selecting the gas pressure after compression in the compressor. The required gas pressure after compression depends on the gas pressure in the mass-transfer column (or separator) and can be calculated using existing software packages for calculating natural gas processing processes (e.g., AEROSYM). For example, with a gas pressure in the column of 10 atm, the gas pressure after compression should be close to 40 atm.

[0053] Since some of the gas depleted in acid fractions circulates from the mass transfer column (or separator) back to the mass transfer column (or separator), its flow rate may be higher than the flow rate of the inlet gas and is limited only by the capacity of the compressor compressing the gas.

[0054] Inside the mass transfer column (or separator), the acid fractions, which mainly consist of carbon dioxide and hydrogen sulfide, are condensed by evaporating liquid methane fed into the mass transfer column (or separator) as part of a two-phase flow fed into the mass transfer column (or separator). Since the heat of evaporation of methane is ~510 kJ / kg, and the heat capacity of methane is 2.4 kJ / (kg K), therefore, in order to cool the inlet gas to the temperature of liquefaction and crystallization of acidic fractions of methane (in the examples below, the required temperature of gas depleted in acidic fractions, for example, is -122 C, and the temperature of the inlet gas is +30 C, therefore the inlet gas must be cooled by 152 C and the cold consumed for this is 152 * 2.4 = 364.8 kJ / kg), it is necessary to supply at least 70% (364.8 / 510 ~ 0.7) of liquefied methane from the inlet gas flow rate for mixing with the inlet gas. For condensation and crystallization of acidic fractions, cold is also required and, consequently, an additional flow rate of liquefied methane.Therefore, even at low concentrations of acid fractions, the minimum amount of liquid methane in the two-phase flow supplied for mixing with the inlet flow must be at least 70 percent of the inlet natural gas flow, so the compressor capacity must be selected so that the gas flow through it is at least 1.7 times greater than the flow rate of the inlet natural gas flow.

[0055] In reality, the flow rate of the acid-depleted gas taken from the top of the column typically exceeds this threshold value (by 1.7 times) than the flow rate of the inlet gas stream, due to the fact that additional cooling is required for condensation and crystallization of the acid fractions.

[0056] For the presented implementation options of the method for purifying natural gas from acidic fractions, taking into account the actual efficiency of the compressors and reasonable undercoupling of the temperature in the heat exchanger, the flow rate of gas depleted in acidic fractions, taken from the top of the column and entering the compressor inlet, is approximately 5.6 times greater than the flow rate of the inlet natural gas.

[0057] In the proposed method, a necessary and mandatory condition for implementing the described process for removing acidic fractions from natural gas is that the compressor capacity be selected such that the gas flow rate through it is at least 1.7 times greater than the inlet natural gas flow rate. No process is known to maintain such a flow ratio. Fulfilling this condition allows for the removal of acidic fractions from natural gas without additional refrigeration cycles using mixed refrigerants, significantly reducing the capital costs of implementing the gas purification process.

[0058] Fig. 1 shows the process according to option 1.

[0059] The method according to the first embodiment of the invention is carried out as follows.

[0060] The feed natural gas stream 1 is fed to the bottom of the mass transfer column 4, in which the feed gas stream is separated into a gas 2 depleted in acid fractions, taken from the top of the column, and a liquid enriched in acid fractions 8, taken from the bottom of the mass transfer column. The gas 2 depleted in acid fractions is heated in the heat exchanger 15, compressed in the compressor 13, cooled sequentially in the cooling apparatus 14 (for example, in the air cooling apparatus) and the heat exchanger 15, expanded in the gas expansion device 12 (for example, in the turbine) and the resulting two-phase stream 7 is fed to the top of the mass transfer column 4; wherein the compressor capacity is selected such that the gas flow rate through it is at least 1.7 times greater than the flow rate of the feed natural gas stream 1.

[0061] Table 1 shows the flow data for the proposed plant according to embodiment 1 of the invention, shown in Figure 1. The flow data contains detailed information on flow rates, pressures, temperatures, and flow compositions. Based on the flow data, it is easy to understand how the plant operates and what equipment is required to implement the proposed method. Figure 2 shows the process according to embodiment 2.

[0062] Table 2 shows the flow data for the proposed installation, according to embodiment 2 of the invention, shown in Figure 2. The flow data contains detailed information on flow rates, pressures, temperatures, and flow compositions. Based on the flow data presented, it is easy to understand how the installation operates and what equipment is required to implement the proposed method.

[0063] The method according to the second embodiment of the invention is carried out as follows.

[0064] A flow of inlet natural gas 1 is fed into a separator or mass-exchange column 4, a gas phase 17 is collected from the top of the separator or mass-exchange column 4 and a liquid and / or crystalline phase 11 from the bottom of the separator or mass-exchange column 4; feeding gas phase 2 from the top of separator or mass-exchange column 4 into additional separator or additional mass-exchange column 16, withdrawing liquid enriched in acidic fractions 8 from the bottom of additional separator or mass-exchange column 16, heating gas depleted in acidic fractions, withdrawn from the top of additional separator or additional mass-exchange column 16, in at least one heat exchanger 15, followed by its compression in compressor 13, sequential cooling in cooling apparatus 14 and heat exchanger 15, expansion in expansion device 12 (for example, in a throttle) and separation of the resulting two-phase flow 7 into first 18 and second 19 parts,the first part 18 of the resulting two-phase flow is fed into the mass-exchange column or separator 4, the second part of the resulting two-phase flow is fed into an additional mass-exchange column or an additional separator 16, wherein the capacity of the compressor 13 is selected so that the gas flow through it is at least 1.7 times greater than the flow rate of the input natural gas flow 1. The calculation models of the units were created in the AEROSYM software package, designed for modeling gas processing plants and natural gas purification units. This software package is included in the register of Russian software of the Ministry of Communications of the Russian Federation.

[0065] Based on the data presented in Tables 1 and 2, any qualified specialist will be able to fully understand how to implement the proposed embodiments of the method for purifying natural gas from acidic fractions. Fig. 3 is a large schematic diagram illustrating the method and system for purifying natural gas from acidic fractions in accordance with the present invention.

[0066] In this diagram, the mixing and separation unit is designated by the number 20. In the first embodiment of the proposed method for purifying natural gas from acidic fractions, this mixing and separation unit is a mass-exchange column within which the two-phase flow 7 is mixed with the inlet natural gas flow and the separation of the liquid enriched in acidic fractions 8. In the second embodiment of the proposed method for purifying natural gas, this mixing and separation unit 20 is a combination of a mass-exchange column (separator) 4 with an additional mass-exchange column (additional separator) 16 and mixing units into which the two-phase flow is fed. In all proposed methods, the two-phase flow 7 is mixed with the inlet natural gas 1 and the separation of the liquid enriched in acidic fractions 8.Thus, in accordance with the proposed methods, the mixing and separation unit may be a single unit or a group of units in which the process of mixing the input natural gas and the two-phase flow and the process of separating the liquid enriched in acidic fractions is combined with other processes, for example, with the process of fractionation, cooling or heating, expansion, compression, etc. In these cases, within the framework of the proposed methods for purifying natural gas from acidic fractions, it is considered that this unit or group of units performs the process of mixing the input natural gas and the two-phase flow and separating the liquid enriched in acidic fractions.

[0067] In all implementations of the proposed method for removing acid fractions from natural gas, it is necessary to extract a portion of the gas depleted in acid gases at any stage of processing. In Figures 1 and 2, the extracted portion of the gas depleted in acid fractions is shown by the number 10. Tables 1 and 2, respectively, indicate the volumes of the extracted portion of the gas depleted in acid fractions.

[0068] As shown in Tables 1 and 2, the mole fraction of acidic fractions in the acid-depleted gas sample is close to 0% (accurate to four decimal places, i.e., complete removal of acidic fractions from the gas is achieved). Meanwhile, the mole concentration of acidic fractions in the acid-enriched liquid exceeds 68%.

[0069] In the proposed methods for purifying natural gas, the liquid enriched with acidic fractions, collected from the bottom of the mass-exchange column (or separator), can be subjected to additional fractionation.

[0070] In all proposed natural gas purification options, it is advisable to treat the incoming natural gas stream before feeding it to the mass-exchange column or separator to remove moisture, mercury, and heavy hydrocarbons. Adsorption units, such as those based on zeolites, can be used for this treatment.

[0071] In all variants of natural gas purification for removing acid fractions, expansion of the acid-depleted gas stream can be performed in a throttle or turbine. When using a turbine, the temperature of the resulting two-phase flow is lower than when using a throttle, so a larger volume of inlet natural gas can be purified using the same compressor. In the first embodiment of the proposed method for natural gas purification for removing acid fractions, the liquid enriched in acid fractions, collected from the bottom of the mass-transfer column, may contain solidified natural gas fractions. These solidified fractions can be removed from the liquid by settling in tanks. Solidified fractions can also be removed from the liquid using hydrocyclones, in which the separation of the solidified fractions occurs in a centrifugal field.

[0072] It should be appreciated that the invention is not limited to the details described above with reference to the preferred embodiments; numerous modifications and variations may be made without departing from the spirit or scope of the invention as defined by the appended claims. In particular, any stream in the proposed method may be subjected to further processing in one or more units. The units may include cooling / heating units, fractionation units, separators, compression and expansion devices, mixing units, etc.

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Claims

CLAUSES OF THE INVENTION 1. A method for purifying natural gas from acidic fractions, comprising the following steps: feeding an input natural gas stream into a mass-exchange column, in which the input gas stream is separated into a gas depleted in acidic fractions, taken from the top of the column, and a liquid enriched in acidic fractions, taken from the bottom of the mass-exchange column; heating the gas depleted in acidic fractions, taken from the top of the column, in at least one heat exchanger, followed by its compression in a compressor, sequential cooling in a cooling apparatus and a heat exchanger, expansion and feeding the resulting two-phase stream to the top of the mass-exchange column; wherein the capacity of the compressor is selected such that the gas flow through it is at least 1.7 times greater than the flow rate of the input natural gas stream.

2. The method according to paragraph 1, characterized in that a portion of the gas depleted in acid fractions is collected at any stage of processing.

3. The method according to claim 1, characterized in that the input natural gas stream is processed before being fed into the mass exchange column to remove moisture, mercury, and heavy hydrocarbons from the natural gas.

4. The method according to paragraph 1, characterized in that the expansion of the gas depleted in acid fractions is carried out in a throttle or turbine.

5. The method according to paragraph 1, characterized in that the liquid enriched in acidic fractions, collected from the bottom of the mass exchange column, is subjected to additional fractionation.

6. The method according to claim 1, characterized in that the liquid enriched in acidic fractions, collected from the bottom of the mass exchange column, contains solidified fractions of natural gas.

7. A method for purifying natural gas from acidic fractions, comprising the following steps: feeding an inlet natural gas stream into a separator or mass-transfer column, collecting a gas phase from the top of the separator or mass-transfer column and a liquid and / or crystalline phase from the bottom of the separator or mass-transfer column; feeding the gas phase from the top of the separator or mass-transfer column into an additional separator or an additional mass-transfer column, collecting gas depleted in acidic fractions from the top of the column and a liquid enriched in acidic fractions from the bottom of the additional separator or an additional mass-transfer column, heating the gas depleted in acidic fractions collected from the top of the additional separator or an additional mass-transfer column in at least one heat exchanger, with subsequent cooling in a compressor, and sequential cooling in a cooling apparatus and a heat exchanger,expanding and separating the resulting two-phase flow into a first and second portion, feeding the first portion of the resulting two-phase flow into a mass-exchange column or separator, feeding the second portion of the resulting two-phase flow into an additional mass-exchange column or an additional separator, wherein the compressor capacity is selected such that the gas flow rate through it is at least 1.7 times greater than the flow rate of the inlet natural gas stream.

8. The method according to paragraph 7, characterized in that a portion of the gas depleted in acid fractions is collected at any stage of processing.

9. The method according to item 7, characterized in that the flow of input natural gas is processed before being fed into the mass exchange column to extract moisture, mercury, and heavy hydrocarbons from the natural gas.

10. The method according to item 7, characterized in that the expansion of the gas depleted in acid fractions is carried out in a throttle or turbine.

11. The method according to paragraph 7, characterized in that the liquid enriched in acidic fractions, collected from the bottom of the mass-exchange column, is subjected to additional fractionation.

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