Method and apparatus for separating mixture comprising at least one fluorinated fluid and one or more contaminants

Abstract

A method and apparatus for recycling a mixture comprising at least one fluorinated fluid, the mixture comprising one or more fluorinated chemical components and one or more contaminants selected from the group consisting of one or more hydrocarbons and / or one or more fluorinated contaminants; the method includes the step of dual membrane filtration to reduce the content of contaminants in the mixture.

Description

Technical Field

[0001] This invention relates to the fields of hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs) and / or hydrochlorofluoroolefins (HCFOs), and to a method for recovering substances contained in a mixture comprising at least one fluorinated fluid and one or more contaminants. Background Technology

[0002] Fluorinated chemical components used as refrigerants, aerosol propellants, fire extinguishing agents, or foaming agents are called hydrofluorocarbons (HFCs) (composed of hydrogen, fluorine, and carbon atoms), hydrofluoroolefins (HFOs), and hydrochlorofluoroolefins (HCFOs) molecules. HFC, HFO and HCFO can be used to implement thermodynamic cycles in refrigeration units (such as cold storage or freezers) or in heat-generating units (such as heat pumps), and can also be used as aerosol propellants, fire extinguishing agents or foaming agents.

[0003] Fluorinated fluids typically consist of pure chemical components, pure molecules, or mixtures of chemical components. The main HFC / HFO / HCFO components are R-1234yf / ze, R-134a, R-32, R-227ea, R-125, R-152a, and R-143a, used alone or in mixtures with other components.

[0004] Document WO 2022 / 078755 A1 describes a method for separating multiple chemical components from a chemical mixture comprising multiple fluorinated fluids, each fluorinated fluid comprising at least one fluorinated component. The method includes an identification step for identifying at least two sub-mixtures, a primary distillation step, and a secondary distillation step.

[0005] Document WO 2011 / 053449 A1 describes a method for separating 1,1,1,2-tetrafluoropropane from a mixture including 1,1,1,2,3-pentafluoropropane and hydrogen fluoride by distillation.

[0006] Document EP 1 038 857 A1 describes a method for separating a mixture comprising 1,1,1,3,3-pentafluorobutane and hydrogen fluoride by distillation.

[0007] Today, HFCs have replaced chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) as refrigerants, aerosol propellants, and in the manufacture of insulating foams because they do not deplete the ozone layer and have a lower global warming potential (GWP) than CFCs. However, they remain a significant contributor to global warming because, despite their relatively short lifespan, their GWP over a century could be thousands of times higher than that of CO2.

[0008] Therefore, regulations on fluorinated gases restrict their use and encourage the recycling and reuse of these products. Reducing their consumption, or at least reducing their emissions into the atmosphere, is one of the challenges for the coming years. HFC emissions have been rising since the 1990s, while current regulations aim to reduce their use. Known HFC alternatives include the use of HFOs or hydrocarbons with much lower GWPs, such as propane (R290). For example, according to the 4th IPCC report, R32 has a GWP of 675, and R125 has a GWP of 3500, while R290 has a GWP of 3.

[0009] Unfortunately, replacing some fluorinated chemicals in refrigerants or refrigerant mixtures with hydrocarbons complicates refrigerant recovery processes, particularly hindering the ability to separate various substances using conventional distillation methods. Therefore, a solution remains needed to improve the recovery of mixed fluorinated fluid mixtures, as these mixtures either contain different types of fluorinated chemicals or a combination of fluorinated chemicals and hydrocarbons. Summary of the Invention

[0010] The object of this invention is to provide a solution to one or more problems and disadvantages encountered in the prior art. Specifically, the object of this invention is to provide a method for recovering multiple chemical components from a chemical mixture, the chemical mixture comprising at least one fluorinated chemical component and one or more contaminants from one or more hydrocarbons and / or one or more fluorinated contaminants.

[0011] Therefore, according to a first aspect, the present invention relates to a method for recycling a mixture comprising at least one fluorinated fluid, the significant feature of which is that it comprises: a) Provide a mixture comprising at least one fluorinated fluid in the form of an initial flow; the mixture comprises one or more fluorinated chemical components and one or more contaminants selected from one or more hydrocarbons and / or one or more fluorinated contaminants; b) Membrane filtration of the initial stream to obtain a purified stream and a contaminant-enriched stream, wherein the contaminant content of the purified stream is lower than that of the initial stream, the membrane filtration comprising at least two sequentially performed membrane filtration sub-steps; and c) Recover the purified stream and / or contaminant enriched stream for reuse and / or recycling.

[0012] As will be clearly seen from the definition just given, this invention proposes to perform dual membrane filtration on a mixture comprising at least one fluorinated fluid to obtain a purified stream depleted of contaminants and a contaminant-enriched stream. According to the invention, the purified stream is the permeate, while the contaminant-enriched stream (e.g., hydrocarbons present at the time) is the residue. This invention is particularly suitable for decontaminating refrigerant mixture streams containing hydrocarbon contaminants and separating fluorinated compound mixtures. The purified streams and / or contaminant-enriched streams produced in this manner can be reused directly or sent to an additional recycling facility including one or more fluorinated chemical component separation units for recycling by conventional means. The significant feature of this invention is that this specific contaminant separation step improves the overall efficiency of methods for recycling mixtures comprising at least one fluorinated fluid. When the content of contaminants such as hydrocarbons is too high, contamination of the mixture comprising at least one fluorinated fluid can affect the yield of distillation processes and may even lead to the recycling of some mixtures. It has been found that implementing a preliminary contaminant separation step can improve distillation capacity, thereby improving the overall efficiency of the recycling method. For fluorinated contaminants, the separation and purification of fluorinated chemical components are improved. In one embodiment, the initial flow comprises one or more fluorinated fluids selected from difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropylene (R1234yf), and trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze).

[0013] In one embodiment, the initial stream comprises one or more fluorinated contaminants, and the fluorinated contaminant is 1,1,1,2,3,3,3-heptafluoropropane (R227ea); and / or the initial stream comprises one or more fluorinated contaminants, and step c) includes the step of recovering the contaminant-enriched stream and recycling it.

[0014] In one embodiment, the initial stream comprises one or more hydrocarbons selected from the group consisting of propane and isobutane; and / or the initial stream comprises one or more hydrocarbons, and step c) comprises the step of recovering the purified stream and recycling it.

[0015] Preferably, the initial stream comprises one or more fluorinated chemical components selected from hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), hydrofluoroolefins (HFOs), and hydrochlorofluoroolefins (HCFOs); more preferably, the initial stream comprises one or more fluorinated chemical components selected from hydrofluorocarbons (HFCs) and / or hydrofluoroolefins (HFOs). According to the present invention, membrane filtration step b) comprises at least two consecutive membrane filtration sub-steps. As shown in the embodiments, implementing two-stage filtration, i.e., arranging at least two membrane filtration modules in series, significantly improves the separation of pollutants such as hydrocarbons. It can be seen that each filtration sub-step generates permeate and residual material, and the second filtration sub-step is carried out on the permeate from the first filtration sub-step.

[0016] Preferably, since each membrane filtration sub-step produces permeate and residue, the residue from the second membrane filtration sub-step is recycled to mix with the initial flow.

[0017] According to a preferred embodiment, membrane filtration step b) includes at least one filtration sub-step using a membrane, said membrane comprising at least one layer of a material selected from polyethersulfone (PES), polysulfone (PSU), polyvinylidene fluoride (PVDF), polyether block amide (PEBA), polypropylene (PP), cellulose acetate (AC), polytetrafluoroethylene (PTFE), sulfonated polyphenylene sulfone (sPPSU), cellulose acetate butyrate (CAB), polyhedral oligomeric silsesquioxane (POSS), or polydimethylsiloxane (PDMS). Preferably, membrane filtration step b) includes at least one filtration sub-step using a membrane, said membrane comprising at least one layer of a material selected as polyether block amide (PEBA) and / or polyethersulfone (PES). For example, membrane filtration step b) includes at least one filtration sub-step using a membrane, the membrane comprising at least one layer of material selected as polyether block amide (PEBA); preferably, the polyamide block comprises at least one polyamide selected from polyamide 6, polyamide 11 and polyamide 12, preferably polyamide 6.

[0018] For example, membrane filtration step b) includes at least one filtration sub-step using a multilayer membrane, the multilayer membrane comprising a layer of material selected as polyether block amide (PEBA) and a layer of polyether sulfone (PES); preferably, the polyamide block comprises at least one polyamide selected from polyamide 6, polyamide 11 and polyamide 12, preferably polyamide 6.

[0019] For example, the initial stream provided in step a) contains a contaminant content by weight percentage greater than or equal to 0.5% of the total weight of the initial stream; for example, greater than or equal to 1.0%. For example, the initial stream provided in step a) contains a contaminant content by weight percentage of 5.0%-40% of the total weight of the initial stream. When the contaminant includes or consists of at least one fluorinated contaminant, the weight percentage of the fluorinated contaminant content included in the initial stream provided in step a) is greater than or equal to 0.5% of the total weight of the initial stream; for example, greater than or equal to 1.0%. For example, the weight percentage of the fluorinated contaminant content included in the initial stream provided in step a) is 5.0%-40% of the total weight of the initial stream. When the contaminants include or consist of at least one hydrocarbon, the weight percentage of hydrocarbons included in the initial stream provided in step a) is greater than or equal to 0.5% of the total weight of the initial stream; for example, greater than or equal to 1.0%. For example, step a) includes the step of identifying one or more contaminants in the initial stream, and when the weight percentage of hydrocarbons is greater than 40% of the total weight of the initial stream, the step further includes a sub-step of diluting the initial stream with another hydrocarbon-free stream to adjust the weight percentage of hydrocarbons to less than 40% of the total weight of the initial stream.

[0020] For example, the initial stream provided in step a) contains hydrocarbons at a weight percentage of 5.0%-40% of the total weight of the initial stream. For example, step b) is performed to obtain a hydrocarbon content of less than 5.0%, preferably less than or equal to 4.0%, even more preferably less than or equal to 3.0%, and even more preferably less than or equal to 2.5% by weight of the total weight of the purified stream. In fact, it has been found that excessively high hydrocarbon contents, such as those exceeding 5.0%, will reduce distillation yields during the recirculation purification of the mixture and / or the contaminant-enriched stream, which may be performed in step c).

[0021] For example, step b) is performed to obtain a purified stream in which the hydrocarbon content is reduced by at least 4 times, preferably at least 5 times, even more preferably at least 6 times, and more preferably at least 8 times compared to the hydrocarbon content of the initial stream.

[0022] In a preferred embodiment, the initial stream comprises at least two fluorinated chemical components, and the recycling step c) comprises separating the fluorinated chemical components by distillation.

[0023] In one embodiment, the purified stream comprises a fluorinated component, and step c) comprises recycling the purified stream by at least one purification step or sub-step; preferably, the purification step is accomplished by simple distillation on at least one simple distillation column.

[0024] In one embodiment, the purified stream is an azeotropic mixture, and step c) includes recycling the purified stream, the recycling comprising one or more distillation sub-steps selected from: - At least one simple distillation sub-step performed on a simple distillation column; and / or - At least one advanced pressure-balanced distillation sub-step; and / or - At least one advanced extraction distillation step.

[0025] Preferably, the purified stream is an azeotropic mixture, and step c) includes recycling the purified stream, the recycling comprising one or more distillation sub-steps, the one or more distillation sub-steps comprising at least one single distillation sub-step performed on a single distillation column, followed by one or more advanced distillation sub-steps selected from: - At least one advanced pressure-balanced distillation sub-step; and / or - At least one advanced extraction distillation step.

[0026] For example, the steps of separating fluorinated chemical components by distillation include: - A sub-step involving the identification of at least two sub-mixtures within a mixture of fluorinated chemical components, each sub-mixture being either a simple sub-mixture comprising a single fluorinated chemical component or a complex sub-mixture comprising a combination of chemical components, each complex sub-mixture belonging to either a first group subjected to secondary distillation by pressure equilibrium distillation or a second group subjected to secondary distillation by extractive distillation. - A primary distillation step using a single distillation column to separate each identified sub-mixture. - An auxiliary distillation step using at least two auxiliary columns for each complex submixture of the first and second groups, wherein the complex submixtures of the first group are separated by pressure equilibrium distillation and the complex submixtures of the second group are separated by solvent extraction distillation.

[0027] According to a second aspect, the present invention relates to an apparatus for carrying out the method according to the first aspect, the apparatus being notable for comprising a membrane filtration unit comprising at least two membrane filtration modules arranged in series.

[0028] Preferably, the apparatus further includes a distillation unit, the distillation unit comprising: - One or more simple distillation columns; and / or - One or more columns configured to implement advanced distillation by extraction; and / or - One or more columns configured to perform advanced pressure-balanced distillation. Preferably, the apparatus further includes a distillation unit, the distillation unit comprising: - One or more simple distillation columns; and - One or more columns configured to perform advanced distillation by extraction. Attached Figure Description

[0029] The invention will be fully understood by referring to the following description given with reference to the accompanying drawings, and other aspects and advantages will also become clear.

[0030] Figure 1 An example embodiment of the device of the present invention is shown.

[0031] Figure 2 A thin-layer composite membrane stage with supply flow and permeate flow models is shown.

[0032] Figure 3 A graph showing the relationship between HFC+HFO concentration and HFC+HFO recovery rate in the permeate stream is presented, illustrating how this relationship varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h -1 Membrane thickness = 2 μm. The feed composition is: 90% HFC + HFO and 10% HC (R600a + R290) by weight.

[0033] Figure 4 A graph showing the relationship between R32+R125 concentration and R32+R125 recovery in the permeate stream is presented, showing how this relationship varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h -1 The film thickness is 2 μm. The composition of the feedstock is: 40% R32, 40% R125, 10% R600a and 10% R290 by weight.

[0034] Figure 5 This study compares the purification effects of single-stage and two-stage methods for HFC+HFO: the relationship between HFC+HFO concentration in the permeate and HFC+HFO recovery varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h. -1 Membrane thickness = 2 μm. The feed composition is: 90% HFC + HFO and 10% HC (R600a + R290) by weight.

[0035] Figure 6 This study compares the purification effects of single-stage and two-stage methods for R32+R125: the relationship between the R32+R125 concentration in the permeate stream and the R32+R125 recovery rate varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h -1 The film thickness is 2 μm. The composition of the feedstock is: 40% R32, 40% R125, 10% R600a and 10% R290 by weight.

[0036] Figure 7This study compares the purification effects of single-stage and two-stage methods on R227ea: the relationship between R227ea concentration in the permeate stream and R227ea recovery varies with supply pressure (1-4 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h -1 The membrane thickness is 2 μm. The composition of the feedstock is 70% R227ea, 20% R1234ze, and 10% R134a by weight. Detailed Implementation

[0037] In the following description, the term "comprising" is synonymous with "including" and is not restrictive, as it allows for the presence of other elements in the described device or other steps in the mentioned method. It should be understood that the term "comprising" includes "consisting of". Throughout the description, the various figures use the same reference numerals to denote the same or similar objects.

[0038] This invention relates to a method for recycling a mixture comprising at least one fluorinated fluid, and an apparatus for carrying out the method. Reference is now made to... Figure 1 The method and the device are described together.

[0039] According to the present invention, a significant feature of the method for recycling a mixture 1 comprising at least one fluorinated fluid is that it comprises: a) Provide a mixture 1 comprising at least one fluorinated fluid in the form of an initial flow 3; said mixture 1 comprising one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more contaminants selected from one or more hydrocarbons and / or one or more fluorinated contaminants; b) Membrane filtration is performed on the initial stream 3 to obtain a purified stream 5 and a contaminant-enriched stream 33 with contaminant content lower than that of the initial stream 3, wherein the membrane filtration includes at least two sequentially performed membrane filtration sub-steps; and c) Recover purified stream 5 and / or contaminant enriched stream 33 for reuse and / or recycling.

[0040] In one embodiment, step c) includes recovering the purified stream 5 and / or the contaminant enrichment stream 33 for reuse. Depending on the composition of the initial mixture, the purified stream 5 and / or the contaminant enrichment stream 33 can be recovered and reused as is (without any further separation or purification steps).

[0041] In a preferred embodiment, step c) includes recovering purified stream 5 for recycling. Recycling of purified stream 5 is achieved by distillation and / or purification of the fluorinated chemical components (41, 43, 49, 51, 55) contained in purified stream 5.

[0042] In a preferred embodiment, step c) involves recovering the contaminant enrichment stream 33 for recycling. Recycling of the contaminant enrichment stream 33 is achieved by distillation and / or purification of one or more fluorinated contaminants and / or one or more hydrocarbons contained in the contaminant enrichment stream.

[0043] According to one embodiment, a significant feature of the method for recycling a mixture 1 comprising at least one fluorinated fluid is that it includes: a) A mixture 1 comprising at least one fluorinated fluid is supplied in the form of an initial flow 3; said mixture 1 comprises one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more hydrocarbons; b) Membrane filtration of the initial stream 3 to obtain a purified stream 5 with a hydrocarbon content lower than that of the initial stream 3, the membrane filtration comprising at least two sequentially performed membrane filtration sub-steps; and c) Recover and recycle the purified stream. According to one embodiment, a significant feature of the method for recycling a mixture 1 comprising at least one fluorinated fluid is that it includes: a) Provide a mixture 1 comprising at least one fluorinated fluid in the form of an initial flow 3; said mixture comprising one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more fluorinated contaminants; b) Membrane filtration is performed on the initial stream 3 to obtain a purified stream 5 and a contaminant-enriched stream 33 with contaminant content lower than that of the initial stream 3, wherein the membrane filtration includes at least two sequentially performed membrane filtration sub-steps; and c) Recover and recycle the pollutant enrichment stream 33.

[0044] The present invention also relates to an apparatus for carrying out the method, the apparatus comprising a membrane filtration unit 7, the membrane filtration unit comprising at least two filtration modules (9, 11).

[0045] Preferably, the device further includes a distillation unit 13, the distillation unit comprising... - One or more individual distillation columns 15; and / or - One or more columns (21, 23) configured to perform advanced distillation by extraction; and / or - One or more columns (17, 19) configured to perform advanced pressure-balanced distillation.

[0046] More preferably, the apparatus further includes a distillation unit 13, the distillation unit comprising... - One or more individual distillation columns 15; and / or - One or more columns (21, 23) configured to perform advanced distillation by extraction.

[0047] Step a) provides a mixture comprising at least one fluorinated fluid.

[0048] According to the present invention, the initial stream 3 is a mixture 1 comprising at least one fluorinated fluid; said mixture comprises one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more contaminants, said contaminants being selected from one or more hydrocarbons and / or one or more fluorinated contaminants. Preferably, the initial stream 3 is a mixture 1 comprising one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more hydrocarbons. Preferably, the initial stream 3 is a mixture 1 comprising one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more fluorinated contaminants. According to the present invention, fluorinated contaminants are fluorinated fluids that can be separated from the mixture because they are mainly present in membrane filtration residues.

[0049] According to the present invention, the fluorinated chemical component is a fluorinated fluid that can be separated from the mixture because it is mainly present in the membrane filtration permeate.

[0050] The components of the mixture have previously been used to implement thermodynamic cycles in multiple independent thermodynamic devices. A thermodynamic device refers to a refrigeration unit (such as a cold storage, freezer, or refrigerator), a heat production unit (such as a heat pump), or an aerosol propellant. The fluorinated fluid can be used in its pure state or in a mixture, and then collected into separate collection containers during collective or selective recovery operations.

[0051] According to a preferred embodiment of the invention, the method further includes a step performed prior to membrane filtration step b): identifying one or more fluorinated fluids in the initial stream. Specifically, the method includes an identification step for identifying one or more contaminants from the initial stream, the contaminants being selected from one or more hydrocarbons and / or one or more fluorinated contaminants.

[0052] For example, the identification step is preferably a qualitative and quantitative analysis step performed by chromatographic analysis, and the device further includes an identification device, preferably a chromatographic analysis system. For example, initial stream 3 includes one or more hydrocarbons selected from the group consisting of methane (R50), ethane (R170), propane (R290), butane (R600), isobutane (R600a), pentane (R601), isopentane (R601a), and propylene (R1270). Preferably, initial stream 3 includes propane (R290) and / or isobutane (R600a). In the context of this invention, one or more hydrocarbons are contaminants because they are primarily present in the leachate.

[0053] For example, the initial stream 3 includes at least one fluorinated contaminant, namely 1,1,1,2,3,3,3-heptafluoropropane (R227ea).

[0054] The weight percentage of contaminant content in the initial stream 3 is 0.3% of the total weight of the initial stream, preferably at least 0.5%, more preferably at least 0.8%, more preferably at least 1.0%, more preferably at least 5.0%, and even more preferably at least 10.0%.

[0055] For example, the weight percentage of contaminant content in the initial stream 3 is between 0.3% and 70% of the total weight of the initial stream, preferably between 0.5% and 60%, more preferably between 1.0% and 50%, and even more preferably between 5.0% and 40% or even between 6.0% and 30%.

[0056] When the contaminants include or consist of fluorinated contaminants, the weight percentage of fluorinated contaminants in the initial stream 3 is, for example, at least 0.3%, preferably at least 0.5%, more preferably at least 0.8%, more preferably at least 1.0%, more preferably at least 5.0%, and even more preferably at least 10.0% of the total weight of the initial stream.

[0057] For example, the weight percentage of fluorinated contaminants in the initial stream 3 is between 0.3% and 70% of the total weight of the initial stream, preferably between 0.5% and 60%, more preferably between 1.0% and 50%, and even more preferably between 5.0% and 40% or even between 6.0% and 30%.

[0058] When the contaminants include or consist of hydrocarbons, the weight percentage of hydrocarbon content in the initial stream 3 is, for example, at least 0.3%, preferably at least 0.5%, more preferably at least 0.8%, more preferably at least 1.0%, more preferably at least 5.0%, and even more preferably at least 10.0% of the total weight of the initial stream.

[0059] For example, the hydrocarbon content of the initial stream 3 is at most 70%, preferably at most 60%, more preferably at most 50%, more preferably at most 40%, more preferably at most 30%, and even more preferably at most 25% of the total weight of the initial stream. When the hydrocarbon content is too high, for example, when the hydrocarbon content of the initial stream is greater than 40% of the total weight of the initial stream, a sub-step can be performed to dilute the initial stream with another hydrocarbon-free stream to adjust the hydrocarbon content to be equal to or less than 40% of the total weight of the initial stream, preferably less than 30%. This dilution step improves the overall efficiency of the method. Therefore, step a) may include a sub-step for adjusting the hydrocarbon content.

[0060] For example, the hydrocarbon content of the initial stream 3 is between 0.3% and 70% by weight, preferably between 0.5% and 60% by weight, more preferably between 1.0% and 50% by weight, and even more preferably between 5.0% and 40% by weight, or even between 6.0% and 30% by weight.

[0061] For example, the initial stream 3 includes one or more fluorinated fluids selected from hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), hydrofluoroolefins (HFOs), and hydrochlorofluoroolefins (HCFOs); more preferably, the initial stream 3 includes one or more hydrofluorocarbons (HFCs) and / or one or more hydrofluoroolefins (HFOs). According to one embodiment of the present invention, the initial stream 3 includes at least one fluorinated chemical component (41, 43, 49, 51, 55), and preferably includes at least two separate fluorinated chemical components (41, 43, 49, 51, 55).

[0062] In one embodiment, the initial flow 3 comprises one or more hydrofluorocarbon (HFC) type fluorinated fluids selected from trifluoromethane (R23), difluoromethane (R32), pentafluoroethane (R125), 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1-difluoroethane (R152a), 1,1,1,2,3,3,3-heptafluoropropane (R227ea), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1,3,3,3-hexafluoropropane (R236fa), trifluoropropane (R263), difluoropropane (R272), fluoropropane (R281), and 1,1,1,3,3-pentafluorobutane (R365mfc). Preferably, the initial stream 3 comprises one or more hydrofluorocarbon (HFC) type fluorinated fluids selected from difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), and 1,1,1-trifluoroethane (R143a). Preferably, the initial stream 3 comprises at least one HFC of difluoromethane (R32) and / or pentafluoroethane (R125).

[0063] In one embodiment, the initial stream 3 comprises one or more hydrofluoroolefin (HFO) type fluorinated fluids selected from cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-Z), trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-E), 2,3,3,3-tetrafluoropropene (R1234yf), and trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze). Preferably, the initial stream 3 comprises at least one HFO of 2,3,3,3-tetrafluoropropene (R1234yf) and / or trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze). In one embodiment, the initial flow 3 comprises one or more hydrochlorofluorocarbon (HCFC) type fluorinated fluids selected from dichlorofluoromethane (R22), chlorofluoromethane (R31), 2,2-dichloro-1,1,1-trifluoroethane (R123), 1-chloro-1,2,2,2-tetrafluoroethane (R124), 1-chloro-1,1,2,2-tetrafluoroethane (R124a), 1,1-dichloro-1-fluoroethane (R141b), 1-chloro-1,1-difluoroethane (R142b), and 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R225cb). In one embodiment, the initial flow 3 comprises one or more hydrochlorofluoroolefin (HCFO) type fluorinated fluids selected from trans-1-chloro-3,3,3-trifluoropropene (R-1233zd(E)), cis-1-chloro-3,3,3-trifluoropropene (R-1233zd(Z)) and (Z)-1-chloro-2,3,3,3-tetrafluoropropene (R-1224yd(Z)).

[0064] For example, the initial flow 3 includes one or more fluorinated fluids selected from difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropylene (R1234yf), and trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze).

[0065] The weight percentage of the fluorinated chemical components (41, 43, 49, 51, 55) in the initial stream 3 is at least 20%, preferably at least 30% or at least 40%, more preferably at least 50%, and most preferably at least 60% of the total weight of the initial stream.

[0066] For example, the weight percentage of the fluorinated chemical components (41, 43, 49, 51, 55) in the initial stream 3 is at most 97%, preferably at most 95%, more preferably at most 92%, and most preferably at most 90% of the total weight of the initial stream. For example, the weight percentage of the fluorinated chemical components (41, 43, 49, 51, 55) in the initial stream 3 is between 30% and 97% of the total weight of the initial stream, preferably between 40% and 95%, more preferably between 50% and 92%, and most preferably between 60% and 90%.

[0067] According to an embodiment of the invention, step a) includes at least one sub-step of pretreating the refrigerant mixture 1 to obtain the initial stream 3. It should be understood that one or more pretreatment sub-steps are performed using a pretreatment unit 25 prior to membrane filtration step b).

[0068] For example, the fluorinated fluid mixture 1 may be compressed for storage purposes, or it may not be compressed. When the fluorinated fluid mixture 1 is not compressed, step a) includes a sub-step of compression in the compression unit 27. In one embodiment of the invention, the initial flow 3 is compressed to a pressure between 1 bar and 10 bar.

[0069] Preferably, before entering the membrane filtration unit 7, the initial flow 3 undergoes one or more pretreatment sub-steps to remove any trace amounts of water, oil, and particles that may damage the membrane surface. This task can be performed by one or more coalescing filters (29, 31) arranged in series, such as two coalescing filters (29, 31) with 0.1 μm and 0.01 μm filter elements, respectively.

[0070] Optionally, according to an embodiment not shown, step a) includes a sub-step of drying the refrigerant mixture in a dehydration unit. Advantageously, this drying sub-step is carried out using a molecular sieve. For example, refrigerant mixture 1 or a portion thereof is compressed to condense at least a portion of the water it contains, thereby generating a two-phase flow having a liquid phase and a gas phase. The gas phase is introduced into the dehydration unit to remove at least a portion of the water it contains and to produce a dried gas phase. Regardless of the pretreatment method chosen, for those skilled in the art, the weight percentage of water content in the initial stream 3 entering the membrane filtration unit 7 is at most 10 ppm of the total weight of the initial stream. For example, step a) includes a sub-step of adjusting the hydrocarbon content of refrigerant mixture 1 by mixing different collected refrigerant streams. In fact, when the content of contaminants such as hydrocarbons is greater than 40% of the total weight of the initial stream, it would be advantageous for someone skilled in the art to dilute the initial stream with another hydrocarbon-free stream. Membrane filtration step b) and membrane filtration unit It should be understood that step b) of membrane filtration of the initial stream 3 to obtain a purified stream 5 with a hydrocarbon content lower than that of the initial stream 3 can also obtain a contaminant-enriched stream 33. Membrane separation is performed in a membrane filtration unit 7 comprising at least one filter module 9, and preferably at least two filter modules (9, 11) arranged in series. When the membrane filtration unit 7 comprises a single filter module 9, the filtration is referred to as single-stage filtration. When the membrane filtration unit 7 comprises multiple filter modules (9, 11) arranged in series, the filtration is referred to as multi-stage filtration. Figure 1 An embodiment is shown in which the membrane filtration unit 7 includes two filtration modules (9, 11) arranged in series.

[0071] Each filtration module (9, 11) comprises one or more membranes arranged in parallel. The membranes may be single-layered or multi-layered, preferably including at least one selective layer for separating hydrocarbons. Two product streams exit the filtration modules (9, 11): one is a permeate stream (5, 35) (or permeate), which includes the portion of the supply stream that has passed through the membrane; the other is a residual stream (33, 37) (or residual), which includes the portion of the supply stream that has not passed through the membrane. According to the invention, the purified stream is the permeate, while the contaminant-enriched stream (e.g., hydrocarbons) is the residual. The residual can then be treated as waste (as in the case of hydrocarbon contaminants) or purified by recycling for reuse (e.g., in the case of fluorinated contaminants such as 1,1,1,2,3,3,3-heptafluoropropane (R227ea)). According to the invention, the method may further include recovering and recycling the filtered residual obtained in step b). Preferably, the residual can be recycled by distillation. Filtration step b) can be a single-stage filtration that includes a single membrane filtration step, or a multi-stage filtration that involves multiple membrane filtration sub-steps performed sequentially. According to the present invention, membrane filtration step b) comprises at least two sequentially performed membrane filtration sub-steps. As shown in the embodiments, multi-stage filtration, i.e., multiple filtration modules (9, 11) arranged in series, can improve the separation performance of hydrocarbons. According to the invention, membrane filtration is carried out in such a manner that contaminants are primarily present in the permeate (33, 37). Since each filtration sub-step produces permeate and permeate, all filtration sub-steps except the first stage filtration are performed on the permeate of the previous filtration sub-step. In the case of two-stage filtration, the second filtration sub-step is performed on the permeate 35 of the first filtration sub-step.

[0072] Preferably, the residue from the filtration sub-steps other than the first-stage filtration is recycled to mix with the initial stream 3. In the case of two-stage filtration, the residue 37 from the second-stage filtration is recycled to mix with the initial stream 3.

[0073] Preferably, the residue 33 from the first filtration sub-step is discharged for further processing.

[0074] Preferably, one or more membranes of one or more filter modules (9, 11) comprise at least one layer made of the following materials: polyethersulfone (PES), polysulfone (PSU), polyvinylidene fluoride (PVDF), polyether block amide (PEBA), polypropylene (PP), cellulose acetate (CA), polytetrafluoroethylene (PTFE), sulfonated polyphenylene sulfone (sPPSU), cellulose acetate butyrate (CAB), polyhedral oligomeric silsesquioxane (POSS), or polydimethylsiloxane (PDMS). More preferably, one or more membranes of one or more filter modules (9, 11) comprise at least one layer made of a polymer or copolymer comprising repeating units of tetramethylene oxide, propylene oxide, or ethylene oxide monomers. For example, the polymer or copolymer comprises repeating units according to formula (1): (1) PA is a polyamide selected from polyamide 6, polyamide 11 and polyamide 12, and PE is poly(ethylene oxide) or poly(tetramethylene oxide); preferably, PA is polyamide 6.

[0075] According to a preferred embodiment of the invention, the material of the filter membrane or at least one layer of the filter membrane is selected as polyether block amide (PEBA). Preferably, the polyamide block comprises at least one polyamide selected from polyamide 6, polyamide 11 and polyamide 12, preferably polyamide 6.

[0076] It is known that copolymers containing polyamide (PA) blocks and polyether (PE) blocks are obtained by cocondensation of polyamide blocks with reactive ends and polyether blocks with reactive ends. For example, this can be achieved through the following: - Polyether diol and polyamide dicarboxylic acid - Polyether diamine and polyamide dicarboxylic acid - Polyether diol and polyamide diamine.

[0077] Document FR 2 273 021 describes such block copolymers of polyether and polyamide, wherein the polyamide blocks and the polyether blocks are linked by ester functional groups. These products are sold by ARKEMA under the trade name PEBAX®. Examples of PEBAs that can be used in the context of this invention are PEBAX® 1074, PEBAX® 2533, and PEBAX® 1657, which are available from ARKEMA. Therefore, according to a preferred embodiment, membrane filtration step b) includes at least one filtration sub-step using a membrane, said membrane comprising at least one layer made of the following materials: polyethersulfone (PES), polysulfone (PSU), polyvinylidene fluoride (PVDF), polyether block amide (PEBA), polypropylene (PP), cellulose acetate (AC), polytetrafluoroethylene (PTFE), sulfonated polyphenylene sulfone (sPPSU), cellulose acetate butyrate (CAB), polyhedral oligomeric silsesquioxane (POSS), or polydimethylsiloxane (PDMS). Preferably, membrane filtration step b) includes at least one filtration sub-step using a membrane, said membrane comprising at least one layer of material selected as polyether block amide (PEBA) and / or polyethersulfone (PES). For example, membrane filtration step b) includes at least one filtration sub-step using a multilayer membrane, one layer of which is selected as polyether block amide (PEBA) and the other layer is selected as polyether sulfone (PES).

[0078] Preferably, step b) is performed to obtain a hydrocarbon content of less than 5.0%, preferably less than or equal to 4.0%, more preferably less than or equal to 3.0%, and even more preferably less than or equal to 2.5% relative to the total weight of the purified stream 5.

[0079] For example, relative to the total weight of the purified stream 5, the weight percentage of hydrocarbon content in the purified stream is between 0.01% and less than 5.0%, preferably between 0.01% and 4.0%, more preferably between 0.01% and 3.0%, and even more preferably between 0.01% and 2.5%.

[0080] Recycle step c) Recirculation step c) is performed on the purified stream 5 and / or the contaminant enrichment stream 33. Preferably, the recirculation step is performed on the contaminant enrichment stream 33 when the initial stream 3 contains one or more fluorinated contaminants. Preferably, the recirculation step is performed on the purified stream 5 when the initial stream 3 contains one or more hydrocarbons.

[0081] According to a preferred embodiment, the initial stream 3 comprises a single fluorinated chemical component (41, 43, 49, 51, 55) and one or more hydrocarbons, and the recycling step c) is performed on the purified stream and is a step for purifying the fluorinated chemical component (41, 43, 49, 51, 55). This purification can be carried out by any means, preferably by distillation.

[0082] According to a preferred embodiment, the initial stream 3 comprises at least two fluorinated chemical components (41, 43, 49, 51, 55) and one or more hydrocarbons, and the recycling step c) is performed on at least the purified stream and includes at least one step of separating the fluorinated chemical components (41, 43, 49, 51, 55). This separation can be carried out by any means, preferably by distillation. Preferably, each separation step capable of separating a fluorinated chemical component, or at least one of the separation steps, is followed by a step of purifying the separated fluorinated chemical component.

[0083] In a preferred embodiment, the initial stream 3 comprises at least one fluorinated chemical component (41, 43, 49, 51, 55) and one or more fluorinated contaminants, and step c) comprises recycling the purified stream 5 and / or the contaminant-enriched stream 33. Recycling of each stream may be achieved by purifying or separating one or more fluorinated contaminants from the one or more fluorinated chemical components.

[0084] According to the present invention, fluorinated contaminants are fluorinated refrigerants that can be separated from the refrigerant mixture because they are mainly present in membrane filtration permeate.

[0085] According to the present invention, the fluorinated chemical component is a fluorinated refrigerant that can be separated from the refrigerant mixture because it is mainly present in the membrane filter permeate.

[0086] Those skilled in the art are familiar with methods for separating fluorinated refrigerants by distillation. For non-azeotropic mixtures, different components can be separated by simple distillation using a simple distillation column. For azeotropic or pseudo-azeotropic mixtures, two advanced distillation methods are known: pressure swing distillation and extractive distillation using a substance called an entrainer or solvent. According to one embodiment of the invention, purified stream 5 is an azeotropic mixture, and step c) is a step of separating fluorinated chemical components (41, 43, 49, 51, 55) and / or a mixture of fluorinated contaminants, said step comprising one or more distillation sub-steps selected from: - A simple distillation sub-step performed on a simple distillation column 15. - Pressure-balanced distillation sub-steps using auxiliary distillation columns (17, 19), and - Extractive distillation steps using auxiliary distillation columns (21, 23).

[0087] Preferably, purified stream 5 is an azeotropic mixture, and step c) is a step of separating fluorinated chemical components (41, 43, 49, 51, 55) and / or a mixture of fluorinated contaminants, said step comprising at least one simple distillation sub-step and one or more advanced distillation sub-steps selected from: - Pressure equilibrium distillation step, and - Extraction and distillation steps.

[0088] Pressure equilibrium distillation is well known to those skilled in the art, and the method involves using two distillation columns (17, 19) operating at different pressures. More specifically, the complex submixture 39 moves sequentially through two towers (17, 19) set at different pressures in a continuous loop. The function of each tower (17, 19) is to separate one of the components (41, 43) of the complex submixture 39 according to its set pressure.

[0089] In the first distillation column 17, which operates primarily at low pressure (P1), one of the two components 41 can be discharged from the bottom of column 17, while the azeotrope is discharged from the top and introduced into the second column 19, which operates at a higher pressure (P2), causing the azeotropic mixture to disappear. In the second column 19, a second compound 43 can be discharged from the bottom, while an azeotropic mixture 57 is formed at the top. The composition of the latter is significantly different from that of the sub-mixture 39. This azeotropic mixture 57 is reintroduced into the first column 17.

[0090] Extractive distillation utilizes a solvent 45, called an entrainer, which increases the volatility of one of the components or drastically alters the activity coefficients of the substances to be separated in different directions, resulting in a separation factor significantly different from 1 (1 = azeotropic point). Two columns (21, 23) are used. Typically, solvent 45 is supplied near the top of the first column 21 (called the extraction column), and the complex sub-mixture 47 to be separated is introduced into the lower region of this column 21 to obtain the best possible mixture. Solvent 45 can be discharged from the bottom of the same column 21 along with one of the substances to be separated, 51. The second column 23 (called the regeneration column) is used to separate (regenerate) solvent 45 and separate the fluorinated compound 51 to be extracted.

[0091] Those skilled in the art are familiar with methods for separating complex mixtures of fluorinated chemical components (41, 43, 49, 51, 55), methods described, for example, in document FR3115036. Therefore, preferably, step c) of separation by distillation includes carrying out the method. Preferably, purified stream 5 is a complex mixture of fluorinated chemical components (41, 43, 49, 51, 55), and step c) includes: - A sub-step in purification stream 5 that identifies at least two sub-mixtures (39, 47, 53), each sub-mixture being either a simple sub-mixture (53) comprising a single fluorinated chemical component (55) or a complex sub-mixture (39, 47) comprising a combination of fluorinated chemical components (41, 43, 48, 51), each complex sub-mixture (39, 47) belonging to either a first group of auxiliary distillations performed by pressure equilibrium distillation or a second group of auxiliary distillations performed by extractive distillation. - A primary distillation step using a single distillation column 15 to separate each identified sub-mixture (39, 47, 53). - Use at least two auxiliary extraction towers to perform auxiliary distillation steps on each complex submixture (39, 47) of the first and second groups, wherein the complex submixture 39 of the first group is separated by pressure equilibrium distillation and the complex submixture 47 of the second group is separated by extractive distillation using solvent 45.

[0092] According to one embodiment of the invention, the same auxiliary column can sequentially perform pressure-balanced distillation and extractive distillation operations. The advantage of this configuration is that it reduces the number of columns in the equipment, thereby lowering related costs.

[0093] Preferably, solvent 45 is selected from the following solvents: n-pentane, dichloromethane, methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), heptanone, pentanone, cyclohexanone, and dimethyl ether. Preferably, the compound used is methyl isobutyl ketone (MIBK). This solvent advantageously provides a high separation factor and high extraction capacity for advanced distillation and recovery of chemical components.

[0094] Preferably, each complex sub-mixture (39, 47) in the first and second groups is subjected to multiple auxiliary distillation steps in sequence.

[0095] Optionally, separating the fluorinated chemical component 55 from the simple sub-mixture 53 includes a purification step performed on the simple sub-mixture 53.

[0096] When step c) includes primary and auxiliary distillation sub-steps, the apparatus for implementing the method according to the invention includes a distillation unit 13, which includes one or more simple distillation columns 15; preferably, the distillation unit 13 further includes at least two auxiliary columns (17, 19, 21, 23) configured to perform advanced distillation by extraction and / or by pressure balancing.

[0097] When the enrichment stream contains one or more fluorinated contaminants, procedures similar to those performed on the purification stream can be performed on the enrichment stream.

[0098] Preferably, the device includes: - Simple distillation column 15, configured to receive purified stream 5 and perform primary distillation to separate purified stream 5 into at least two sub-mixtures. - An electronic computer, configured as follows: • Identify different submixtures (39, 47, 53) in the chemical mixture, each of which is a simple submixture 53 comprising a single chemical component 55 or a complex submixture (39, 47) comprising a combination of chemical components (41, 43, 49, 51). • Each complex submixture (39, 47) was assigned to either Group 1, which used pressure balancing for assisted distillation, or Group 2, which used extractive distillation for assisted distillation. - At least two auxiliary columns (17, 19, 21, 23) are configured to perform auxiliary distillation and be able to distill by extraction and / or by pressure equilibration using entrainers to separate all chemical components (41, 43, 49, 51) from each submixture (39, 47).

[0099] Preferably, the two auxiliary columns are configured to perform assisted distillation and sequential extractive distillation using an entrainer, followed by pressure equilibrium distillation, to separate all chemical components from each submixture.

[0100] Example Example 1 Selection of membrane and refrigerant mixture The results shown in the following examples were obtained using simulation software that used ideal (non-competitive) experimental penetration and selectivity data obtained at the laboratory scale.

[0101] The membrane material used in this project is a polyether block amide, a thermoplastic elastomer composed of flexible polyethylene oxide units (PEO, 60 wt.%) and glassy polyamide 6 hard segments (PA6, 40 wt.%). The polyamide segments impart mechanical strength to the polymer and prevent PEO crystallization, thereby obtaining a polymer material with good film-forming properties and high gas permeability. The membrane thickness is 2 µm. Analysis of experimental results on the pure permeation properties of seven HFCs, HFOs, and two hydrocarbons in polymer membranes led to the definition of two refrigerant mixtures, M1 and M2, the composition of which is shown in Table 1. The table also indicates the presence of a fluorinated refrigerant mixture, M3.

[0102] Table 1 The composition of different refrigerant mixtures as a percentage of the total weight of the mixture.

[0103] Mixture M1 comprises HFCs, HFOs, and hydrocarbons. It is an R448A type mixture in which 10% by weight of R32 has been replaced by hydrocarbons.

[0104] Mixture M2 comprises HFCs and hydrocarbons. It is an R410A type mixture in which 20% by weight of HFCs has been replaced by hydrocarbons.

[0105] Mixture M3 includes HFC-type fluorinated contaminants, namely 1,1,1,2,3,3,3-heptafluoropropane (R227ea).

[0106] HFC -R32: Difluoromethane -R125: Pentafluoroethane -R134a: 1,1,1,2-Tetrafluoroethane -R227ea: 1,1,1,2,3,3,3-heptafluoropropane HFO -R1234yf:2,3,3,3-Tetrafluoropropylene -R1234ze: trans-1,3,3,3-tetrafluoroprop-1-ene hydrocarbons -R600a: Isobutane -R290: Propane Example 2 Methods for implementing single-stage membrane separation units and hydrocarbon separation The membrane separation step was carried out at a temperature of 25°C and a maximum pressure of 8.0 bar.

[0107] The mathematical model of the membrane separation unit is constructed based on the following assumptions: - The permeability of a gas through a dense membrane is described by a solution diffusion mechanism, which means that the permeability coefficient (P) is defined as the adsorption coefficient (P). S ) and diffusion coefficient ( D The product of ).

[0108] (1) in S It is an equilibrium term related to the concentration of components in the polymer phase, and D It is a kinetic term related to the molecular motion of the permeating components as they pass through the membrane.

[0109] The transport of gas through a dense selective barrier follows the expression below.

[0110] (2) inJ i It is the molar flow rate of component i. P i It is the gas permeability coefficient. δ It is the film thickness. P R,i and P P,i These are the partial pressures of the components on both sides of the membrane.

[0111] - Gas permeability is independent of the composition of the supply (ideal gas permeability), meaning the simulation results do not account for the seemingly reasonable competitive effect of supplying gas mixtures to the membrane.

[0112] - Gas permeability is pressure-dependent. The permeability data for each HFC, HFO, and HC is described as a function of the pressure gradient applied across the membrane, following an exponential relationship (Δ). P i ).

[0113] (3) in P 0,i It refers to the pre-factor. m This is a constant reflecting the effect of pressure on gas permeability. Table 2 provides a summary of the adjusted parameter values ​​for each gas.

[0114] - A piston flow concentration model was developed for the supply gas and permeate gas circulating in the channels on both sides of the membrane.

[0115] - The pressure drop of the gas phase along the supply side is negligible.

[0116] -Isothermal operation.

[0117] Table 2: The exponential adjustment parameters of equation (3) for HFC, HFO and HC.

[0118]

[0119] Figure 2 A schematic diagram of a gas separation process using a planar thin-layer composite membrane is shown.

[0120] The derivation of the differential mass balance around each component in the length slice dz is as follows. (4) (5) Where F i It is the molar flow rate of component i. A is the membrane surface area, and z is the axial position along the module length. Additionally, Equation 2 defines the values ​​for each component (J). iThe transmembrane flow rate is ). Therefore, the proposed mathematical model consists of equations (2), (3), (4) and (5).

[0121] Performance of the separation process The performance of the separation process is evaluated by the purity of the product and the recovery rate of the target stream product (which may be permeate or residual material, depending on the specific case study). In each case study, the product recovery rate is defined by Equation (6), and the purity is given by the mass concentration of the target component in the product stream.

[0122] (6) Filtration of mixture M1 Figure 3 The relationship between the concentration of HFC+HFO in the permeate stream of mixture 1 and the HFC+HFO recovery rate is shown, and this relationship varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg·h -1 Membrane thickness = 2 μm. The feed composition is: 90% HFC + HFO and 10% HC (R600a + R290) by weight.

[0123] Table 3 shows an example of the membrane separation performance of mixture M1. Table 3

[0124] It can be seen that the HFC+HFO recovery rate and purity by weight percentage were 60.4% (in the residue) and 93.7% (in the permeate), respectively. These product specifications were based on a supply pressure of 3.7 bar and a permeate surface area of ​​17 m². 2 The membrane module was used to obtain the membrane.

[0125] Filtration of mixture M2 Figure 4 The relationship between the concentration of R32+R125 in the permeate stream and the recovery rate of R32+R125 is shown, which varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. Supply flow rate = 10 kg / h -1 The film thickness is 2 μm. The composition of the feedstock is: 40% R32, 40% R125, 10% R600a and 10% R290 by weight.

[0126] Table 4 shows an example of the membrane separation performance of mixture M2 (membrane surface area: 5.1 m²). 2 ) Table 4

[0127] It can be seen that by using a single-stage membrane unit with a permeable surface area of ​​5 m², and a supply pressure of 7.4 bar, the weight percentage of HC content in the product stream can be reduced from 20% to 5.5%. The weight percentages of R32+R125 recovery and purity are 61.4% and 94.5%, respectively.

[0128] Table 5 shows another example of the membrane separation performance of mixture M2 (membrane surface area: 17 m²). 2 ) Table 5

[0129] In this case, a much lower pressure of 3.6 bar must be applied to achieve a weight percentage recovery of 60.2% and a purity of 92.6% for R32+R125. Example 3 Utilizing a two-stage membrane separation unit and a hydrocarbon method In a two-stage design, the permeate from the first membrane unit is typically recompressed and sent to the second membrane unit, where further separation is performed. The final permeate is thus enriched twice. Furthermore, because the gas volume processed through the second membrane unit is smaller than that of the first stage, the membrane surface area in the second stage is smaller, and the required compression power is not significantly increased compared to a single-stage method.

[0130] Filtration of mixture M1 Figure 5 This study compares the purification effects of single-stage and two-stage methods for HFC+HFO. It demonstrates the relationship between the HFC+HFO concentration in the permeate stream and the HFC+HFO recovery rate, which varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. The supply flow rate is 10 kg / h. -1 Membrane thickness = 2 μm. The feed composition is: 90% HFC + HFO and 10% HC (R600a + R290) by weight.

[0131] As can be seen, this configuration improves product specifications compared to the single-stage method because it reduces the weight percentage of HC content in the permeate stream from an initial 10% to a lower hydrocarbon concentration (<2%), while maintaining the weight percentage of HFC+HFO recovery at approximately 60%.

[0132] Figure 1The diagram shows a two-stage membrane separation unit. The unit includes two filtration modules connected in series; the first module has a membrane surface area of ​​57 m². 2 The membrane surface area of ​​the second module is 5 m². 2 Initially, only the initial flow is supplied to the first module. Then, once feasible, the residue from the second module is recycled back to the inlet of the first module to mix with the initial flow, thereby altering the composition of the stream entering the first module. The results given in Table 6 illustrate an equilibrium state.

[0133] Table 6

[0134] It can be seen that the target purity of HFC+HFO is 98.3% and the recovery rate is 68.8%. The specifications of this product are as follows: first-stage supply pressure is 4.8 bar, second-stage supply pressure is 8 bar, and membrane surface area is 57 m². 2 and 5 m 2 It was obtained from the module.

[0135] The hydrocarbon content in the initial flow, which is 10% by weight, will be reduced to less than 2% in the second-stage permeate (a reduction of 5 times).

[0136] Filtration of mixture M2 Figure 6 This study compares the purification efficiency of single-stage and two-stage methods for R32+R125. It demonstrates the relationship between the concentration of R32+R125 in the permeate stream and its recovery rate, which varies with supply pressure (1-8 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. The supply flow rate is 10 kg / h. -1 Membrane thickness = 2 μm. The composition of the supply is: 40% R32, 40% R125, 10% R600a and 10% R290 by weight percentage.

[0137] The same applies. Figure 7 The method shown involves recycling the second-stage permeate back into the supply stream of the first module, the difference being that the membrane surface area in the first module is 80 m². 2 The membrane surface area in the second filtration module is 5 m². 2 The balance results are shown in Table 7.

[0138] Table 7

[0139] As can be seen, the two-stage filtration process reduced the HC content by weight percentage from an initial 20% to approximately 2% (a 10-fold reduction), and achieved a higher level of recovery (65%) compared to single-step separation. This separation used two membranes with surface areas of 80 m² each. 2 and 5 m 2 This was achieved using membrane units. The weight percentages of recovery and purity of R32+R125 were 64.8% and 97.9%, respectively.

[0140] Example 4 A method utilizing a two-stage membrane separation unit and fluorinated contaminants.

[0141] In a two-stage design, the permeate from the first membrane unit is typically recompressed and sent to the second membrane unit, where further separation is performed. The final permeate is thus enriched twice. Furthermore, because the gas volume processed through the second-stage membrane unit is smaller than that of the first stage, the membrane surface area of ​​the second stage is smaller, and the required compression power is not significantly increased compared to a single-stage process. When the contaminant is a fluorinated contaminant, these fluorides, referred to as contaminants, can be separated for recirculation.

[0142] Filtration of mixture M3 Figure 7 This paper compares the effectiveness of single-stage and two-stage methods for separating the fluorinated compound R227ea. It demonstrates the relationship between the R227ea concentration in the permeate stream and the R227ea recovery rate, which varies with supply pressure (1-4 bar) and membrane surface area. Each data point represents a combination of supply pressure and membrane surface area. The supply flow rate is 10 kg / h. -1 The membrane thickness is 2 μm. The composition of the feedstock is 70% R227ea, 20% R1234ze, and 10% R134a by weight.

[0143] The same applies. Figure 5 The method shown involves recycling the second permeate back into the supply stream of the first module, the difference being that the membrane surface area in the first module is 15.3 m². 2 The membrane surface area in the second filtration module is 21.8 m². 2 The balance results are shown in Table 8.

[0144] Table 8

[0145] As can be seen, the two-stage filtration process resulted in recoveries of the fluorinated chemical contaminant R227ea from the first and second filtrates of 68% and 85%, respectively. This contaminant can then be purified and recycled.

Claims

1. A process for recycling a mixture (1) comprising at least one fluorinated fluid, characterized in that, The method comprises the following steps: a) providing a mixture (1) comprising at least one fluorinated fluid in the form of an initial flow (3), said mixture comprising one or more fluorinated chemical components (41, 43, 49, 51, 55) and one or more contaminants selected from one or more hydrocarbons and / or one or more fluorinated contaminants; b) subjecting the initial flow (3) to membrane filtration to obtain a purified flow (5) and a contaminant-enriched flow (33), the contaminant content of the purified flow (5) being lower than the contaminant content of the initial flow (3); the membrane filtration comprising at least two membrane filtration sub-steps performed sequentially; and c) recovering the purified flow (5) and / or the contaminant-enriched flow (33) for reuse and / or recycling.

2. The recycling method of claim 1, wherein, The initial flow (3) comprises one or more fluorinated contaminants and the fluorinated contaminants are 1,1,1,2,3,3,3-heptafluoropropane (R227ea).

3. The recycling method according to claim 1 or 2, characterized in that, The initial flow (3) comprises one or more fluorinated contaminants and step c) comprises the step of recovering the contaminant-enriched flow (33) and recycling it.

4. The recirculation method of any one of claims 1 to 3, wherein, The initial flow (3) comprises one or more hydrocarbons selected from the group comprising propane and isobutane.

5. The recirculation method of any one of claims 1 to 4, wherein, The initial flow (3) comprises one or more hydrocarbons and step c) comprises the step of recovering the purified flow (5) and recycling it.

6. The recirculation method of any one of claims 1 to 5, wherein, The membrane filtration step b) comprises at least one filtration sub-step using a membrane comprising at least one layer of polymeric material selected from polyether sulfone, polysulfone, polyvinylidene fluoride, polyether block amide, polypropylene, cellulose acetate, polytetrafluoroethylene, sulfonated polyphenylsulfone, cellulose acetate butyrate, polyhedral oligomeric silsesquioxane or polydimethylsiloxane.

7. The recirculation method of any one of claims 1 to 6, wherein, The membrane filtration step b) comprises at least one filtration sub-step using a membrane comprising at least one layer of material selected as polyether block amide; preferably, the polyamide block comprises at least one polyamide selected from polyamide 6, polyamide 11 and polyamide 12, preferably polyamide 6.

8. The recycling method according to one of claims 1 to 7, characterized in that, The initial flow (3) comprises one or more fluorinated chemical components (41, 43, 49, 51, 55) selected from hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs); more preferably, the initial flow comprises one or more fluorinated chemical components selected from hydrofluorocarbons (HFCs) and / or hydrofluoroolefins (HFOs).

9. The recirculation method of any of claims 1 to 8, wherein, The initial flow (3) comprises one or more fluorinated fluids (41, 43, 49, 51, 55) selected from difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (R1234yf) and trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze).

10. The recirculation method of any one of claims 1 to 9, wherein, The initial flow supplied in step a) has a weight percentage of contaminant content greater than or equal to 0.5% of the total weight of the initial flow (3); preferably, the weight percentage of contaminant content is between 5.0% and 40% of the total weight of the initial flow.

11. The recirculation method of any of claims 1 to 10, wherein, The initial stream supplied in step a) has a hydrocarbon content by weight greater than or equal to 0.5% of the total weight of said initial stream (3); preferably, between 5.0% and 40%.

12. The recirculation method of any one of claims 1 to 11, wherein, The initial stream supplied to step a) comprises one or more hydrocarbons and step b) is performed to obtain a hydrocarbon content by weight less than 5.0% with respect to the total weight of said purified stream (5).

13. The recirculation method of any one of claims 1 to 12, wherein, Said initial stream (3) comprises at least two fluorinated chemical components (41, 43, 49, 51, 55) and step c) of recycling said purified stream (5) comprises separating said fluorinated chemical components (41, 43, 49, 51, 55) by distillation.

14. The recycling method of claim 13, wherein, The step of separating said fluorinated chemical components (41, 43, 49, 51, 55) by distillation comprises: - a sub-step of identifying at least two sub-mixtures (39, 47, 53) within the mixture of fluorinated chemical components (41, 43, 49, 51, 55), each sub-mixture being a simple sub-mixture (53) comprising a single fluorinated chemical component (55) or a complex sub-mixture (39, 47) comprising a combination of chemical components (41, 43, 49, 51), each complex sub-mixture (39, 47) belonging to a first group subjected to secondary distillation by pressure swing distillation or to a second group subjected to secondary distillation by extractive distillation, - a primary distillation using a single distillation column (15) to separate each identified sub-mixture (39, 47, 53); - an auxiliary distillation of each complex sub-mixture (39, 47) of said first group and of said second group using at least two auxiliary columns (17, 19, 21, 23), the complex sub-mixtures (39) of said first group being separated by said pressure swing distillation and the complex sub-mixtures (47) of said second group being separated by said extractive distillation using a solvent (45).

15. The recirculation method of any one of claims 1 to 14, wherein, Since each membrane filtration sub-step produces a permeate and a retentate, the retentate produced by the second membrane filtration sub-step is recycled to be mixed into said initial stream.

16. The recirculation method of any one of claims 1 to 15, wherein, Step a) comprises a step of identifying one or more contaminants in said initial stream and, when the hydrocarbon content by weight is greater than 40% of the total weight of said initial stream, a sub-step of diluting said initial stream with another flow free of hydrocarbons to adjust the hydrocarbon content by weight to less than 40% of the total weight of said initial stream.

17. An apparatus for carrying out the method for recycling a mixture (1) comprising at least one fluorinated fluid according to any one of claims 1 to 16, characterized in that, The apparatus comprises a membrane filtration unit (7) comprising at least two membrane filtration modules (9, 11) arranged in series. The apparatus comprises a membrane filtration unit (7) comprising at least two membrane filtration modules (9, 11) arranged in series.

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