Production of synthetic fuel from carbon dioxide with carbon dioxide separation

Abstract

The invention relates to a device / method for capturing / converting CO2. The present invention relates to a process for producing CO and water, comprising / using a CO2 capture unit (2) that produces a CO2-rich effluent (3), a water electrolysis unit (5) that converts water (4) into oxygen (6) and hydrogen (7), an RWGS unit (8) that treats the CO2-rich effluent with hydrogen (7) and produces an RWGS gas (9) enriched in CO and water, an FT unit (13) that converts the RWGS gas and produces an FT effluent (14), a first separation unit (15) that treats the FT effluent and produces a hydrocarbon effluent (17) and a gas effluent (33), a second separation unit (34) separating the first gas (33) producing a CO2-lean gas (18) and a CO2-rich gas (35) fed to the RWGS unit, a hydrogen unit (20) treating the hydrocarbon effluent to produce a hydrocarbon fraction (21).

Description

Field of the Invention

[0001] The present invention relates to the production of very high quality (substantially sulfur, aromatic or nitrogen free) synthetic fuels, namely gasoline, kerosene, gas oil and / or other hydrocarbon products such as naphtha or lubricant base oils. More particularly, an object of the present invention is to produce synthetic fuels from carbon dioxide (CO2) and hydrogen (H2).

[0002] The capture of carbon dioxide according to the present invention and its conversion into fuel base stock comprises two successive steps: the conversion of carbon dioxide and hydrogen into synthesis gas consisting mainly of CO + H2, and then the conversion of the synthesis gas into synthetic hydrocarbons by the Fischer-Tropsch (FT) process. The properties of the products from the Fischer-Tropsch process can be adjusted by suitable post-treatment operations to obtain the desired fuel specifications. Prior Art

[0003] The conversion of a mixture of carbon dioxide and hydrogen into synthesis gas CO + H2 using the reverse water gas shift (RWGS) conversion process has long been known to those skilled in the art. This also applies to the Fischer-Tropsch synthesis process, which enables the conversion of synthesis gas into a mixture of paraffins and / or olefins depending on the catalyst and operating conditions. In the case of producing paraffins, it is preferred to improve certain of their properties so that they can be used in transportation applications.

[0004] A series of unit operations have been the subject of patent applications, these series of unit operations being aimed at converting carbon dioxide into fuel base stock, commonly referred to as e-fuels.

[0005] For example, patent application US2010 / 0280135A1 can be mentioned, which describes a renewable Fischer-Tropsch synthesis process which enables the production of hydrocarbons and alcohols from wind energy, residual carbon dioxide and water. The process comprises the following unit operations: electrolysis of water to produce hydrogen and oxygen, an RWGS reactor for producing synthesis gas, and Fischer-Tropsch synthesis in a high temperature multitubular reactor. Various recycle options are described (for example, recycle after separation of unreacted carbon dioxide from RWGS, recycle of ex-FT carbon dioxide to RWGS, recycle of ex-FT unreacted H2 and CO to FT).

[0006] However, patent application US2010 / 0280135A1 does not mention the possibility of advantageously integrating the unit operations with a carbon dioxide capture process. Nor does it mention the thermal integration between the various heat sources generated by the unit operations.

[0007] Patent Application US2007 / 0244208A1 relates to a method for producing high-octane fuels from carbon dioxide and water. The raw materials are industrial carbon dioxide and water. The final products can be high-octane gasoline, high-cetane diesel, or other liquid hydrocarbon mixtures suitable for driving conventional internal combustion engines or hydrocarbons suitable for further industrial processing or commercial use. Products such as dimethyl ether or methanol can also be withdrawn from the production line. The heat generated by the exothermic reaction in this method is fully utilized, and the heat generated by the production process and the heat generated by the reprocessing of hydrocarbons not suitable for liquid fuels are also fully utilized.

[0008] However, Patent Application US2007 / 0244208A1 does not mention the possibility of advantageously integrating unit operations with the carbon dioxide capture process. Nor does it mention recycling from the Fischer-Tropsch reactor to maximize fuel production.

[0009] Patent Application US2012 / 0079767A1 describes a method and system for producing syngas by combining hydrogen and carbon monoxide from different sources while controlling the molar ratio (H2 / CO) of the produced syngas. Hydrogen is produced by the electrolysis of water. Carbon monoxide is produced by reacting carbon dioxide captured from the exhaust of a stationary internal combustion engine with hydrogen in a RWGS reactor. Hydrocarbon fuels are produced from the syngas by Fischer-Tropsch synthesis.

[0010] However, Patent Application US2012 / 0079767A1 does not mention the possibility of advantageously integrating unit operations with the carbon dioxide capture process. Nor does it mention recycling from the Fischer-Tropsch reactor to maximize fuel production.

[0011] Patent Application US2007 / 0142481A1 describes a method for synthesizing hydrocarbons, which includes introducing hydrogen and carbon monoxide into a first Fischer-Tropsch reaction stage, which can partially catalytically react hydrogen and carbon monoxide to form hydrocarbons. At least a part of the tail gas containing unreacted hydrogen and carbon monoxide obtained from the first reaction step is introduced into a second Fischer-Tropsch reaction step, which is a two-phase high-temperature catalytic Fischer-Tropsch reaction step. Hydrogen and carbon monoxide can be at least partially catalytically reacted in the second reaction step to form gaseous hydrocarbons. This patent application is characterized by the presence of two Fischer-Tropsch reactors in series, and the second reactor processes the unreacted syngas from the first reactor. There is no recycling of carbon dioxide or water.

[0012] Therefore, the analysis of the prior art shows that the sequence of RWGS and Fischer-Tropsch unit operations enables the production of a synthetic base for fuels from carbon dioxide and hydrogen, and hydrogen may be produced by electrolyzing water using a power source such as solar energy or wind energy in some cases.

[0013] However, these documents do not provide any elements regarding the possibility of integrating unit operations with a carbon dioxide capture process that supplies raw materials containing a carbon source to produce fuel and the unexpectedly positive results. Summary of the Invention

[0015] In the above context, the first object of the present specification is to overcome the problems of the prior art and capture and upgrade carbon dioxide in the form of synthetic fuel that can be used for transportation means.

[0016] The present invention relates to the capture and conversion of carbon dioxide to produce CO+H2 syngas, and the conversion of the syngas to synthetic hydrocarbons by the Fischer-Tropsch reaction. Then, the characteristics of the effluent from the Fischer-Tropsch synthesis can be adjusted by a post-treatment method (upgrading) to make them compatible with the uses for land, aviation, and marine fuels. The gas produced at the outlet of the Fischer-Tropsch reactor can also be upgraded to synthetic methane (e-methane), synthetic natural gas SNG (e-SNG), or LPG (e-LPG).

[0017] Specifically, the present invention relates to an apparatus and method for producing synthetic fuel from carbon dioxide and hydrogen, which can improve the production of the product of interest. Advantageously, the method can also minimize the energy requirement for producing the fuel through original heat integration.

[0018] The present invention is based on the presence of a unit for separating carbon dioxide contained in the gas effluent from the Fischer-Tropsch reaction section; recycling the carbon dioxide separated from the gas effluent to the inlet of the RWGS reaction section. Thus, the gas effluent that can be sent to the air combustion section basically no longer contains carbon dioxide.

[0019] Preferably, the presence of the air combustion unit enables the generation of a gas effluent containing carbon dioxide, nitrogen, and steam by burning the gaseous hydrocarbon by-products of the method. Advantageously, the gas effluent can be returned to the inlet of the carbon dioxide capture unit to capture carbon dioxide and then upgrade it in the RWGS reaction unit. Advantageously, the release of heat generated by air combustion enables the supply of thermal energy to other units of the method, such as the RWGS reaction unit and / or the carbon dioxide capture unit, thereby limiting the external supply of the required thermal energy.

[0020] The energy integration of the method also enables power generation through heat recovery. This heat converted into electricity can supply energy for the electrolysis of water and / or for the RWGS reactor and / or for the capture unit that converts carbon dioxide and hydrogen into syngas.

[0021] Advantageously, the hydrogen produced by the electrolysis of water can be used for the conversion of carbon dioxide, Fischer-Tropsch synthesis, and work-up. Preferably, the hydrogen required in the process is provided entirely by the water electrolysis unit. Thus, the process according to the invention does not require an external hydrogen supply, such as hydrogen produced by steam reforming of natural gas. The electrolyzer is preferably operated with low-carbon electricity, which contributes to the renewable nature of the fuel and the gas produced. In addition, the water used for hydrogen production can at least partly be sourced from the recycling of water produced in the various steps of the process, which has the advantage of limiting the external water supply.

[0022] According to a first aspect, the above object and other advantages are achieved by a device for capturing and converting a carbon dioxide-containing feedstock, the device comprising the following units:

[0023] - a unit for capturing carbon dioxide from the feedstock, which uses, for example, at least one amine-based solvent, at least one physical solvent such as based on polyethylene glycol dimethyl ether, and / or a physical adsorption device operating by temperature swing adsorption, and which is adapted to produce a carbon dioxide-rich effluent;

[0024] - a water electrolysis unit, which is suitable for converting water to produce oxygen and hydrogen;

[0025] - a reverse water gas shift (RWGS) reaction unit, which is adapted to treat the carbon dioxide-rich effluent with hydrogen and produce an RWGS gas enriched in carbon monoxide and water;

[0026] - a Fischer-Tropsch reaction unit, which is adapted to: convert the RWGS gas and produce a FT effluent, and optionally generate a first water vapor, which is generated, for example, by vaporizing water in an exchanger located within the Fischer-Tropsch reaction unit, to supply heat energy to the carbon dioxide capture unit;

[0027] - a first separation unit, which is adapted to at least partly treat the FT effluent and produce: a hydrocarbon effluent, a first water effluent optionally at least partly recycled to the inlet of the water electrolysis unit, and a first gas effluent;

[0028] - a second separation unit, which is adapted to treat the first gas effluent and produce: a carbon dioxide-rich gas effluent at least partly sent to the RWGS reaction unit and a carbon dioxide-lean gas effluent optionally at least partly recycled to the Fischer-Tropsch reaction unit; and

[0029] - a hydrogen reaction unit (hydrotreating and / or hydrocracking and / or hydroisomerization unit), which is adapted to treat the hydrocarbon effluent and produce at least one hydrocarbon fraction, for example meeting the specifications for transportation applications.

[0030] According to one or more embodiments, the apparatus includes an air combustion reaction unit adapted to at least partially oxidize the carbon dioxide-lean gas effluent to produce a combustion effluent comprising carbon dioxide and water and to send the combustion effluent to a carbon dioxide capture unit.

[0031] According to one or more embodiments, the air combustion reaction unit is adapted to generate heat for supplying thermal energy to the RWGS reaction unit and / or the carbon dioxide capture unit (via a feed line), for example by heat exchange to heat the carbon dioxide-rich effluent and / or the carbon dioxide-rich gas effluent and / or hydrogen, or by integrating the reaction section of the RWGS reaction unit into the chamber of the air combustion unit.

[0032] According to one or more embodiments, a portion of the hydrogen is supplied downstream of the RWGS reaction unit and upstream of the Fischer-Tropsch reaction unit.

[0033] According to one or more embodiments, the feed / effluent heat exchange enables the heat available in the RWGS effluent to be used to preheat the gas (the gas rich in CO2 and H2) entering the RWGS reaction unit.

[0034] According to one or more embodiments, the apparatus includes a first heat exchanger adapted to generate a second steam by heat exchange between water and the RWGS gas, which can be used, for example, to supply thermal energy to the carbon dioxide capture unit.

[0035] According to one or more embodiments, the apparatus includes a first turbine for processing at least a portion of the carbon dioxide-lean gas effluent separated by the first separation unit to generate electricity.

[0036] According to one or more embodiments, the second turbine is adapted to at least partially process the first steam and / or the second steam to generate electricity.

[0037] According to one or more embodiments, the electricity is used to supply thermal energy to the RWGS reaction unit and / or the carbon dioxide capture unit and / or the water electrolysis unit.

[0038] According to one or more embodiments, the electricity is used to supply thermal energy to the regeneration section of the carbon dioxide capture unit.

[0039] According to one or more embodiments, the water electrolysis unit processes water from a make-up line and / or from the RWGS gas and / or from the FT effluent.

[0040] According to one or more embodiments, the water from the RWGS gas is at least partially or completely separated by a third separation unit and sent to the water electrolysis unit.

[0041] According to one or more embodiments, the carbon dioxide-rich effluent and / or the carbon dioxide-rich gaseous effluent is purified either separately or after mixing before being introduced into the RWGS reaction unit. In one or more embodiments, the RWGS gas is purified either upstream or downstream of the third separation unit before being introduced into the Fischer-Tropsch reaction unit. According to one or more embodiments, the first water effluent is purified before being introduced into the water electrolysis unit. The effluent purification step aims to remove at least partially sulfur-containing compounds, nitrogen-containing compounds, halogens, heavy metals and transition metals. The main techniques for purifying gases are: adsorption, absorption, catalytic reaction.

[0042] According to one or more embodiments, the apparatus comprises a carbon dioxide separation unit arranged between the RWGS reaction unit and the Fischer-Tropsch reaction unit. Advantageously, the size of the FT reaction unit 13 can thus be reduced.

[0043] According to a second aspect, the above object and other advantages are obtained by a method for capturing and converting carbon dioxide, the method comprising the following steps:

[0044] - Treating a feedstock in a carbon dioxide capture unit to produce a carbon dioxide-rich effluent;

[0045] - Converting water in a water electrolysis unit to produce oxygen and hydrogen;

[0046] - Treating the carbon dioxide-rich effluent with hydrogen in a reverse water gas shift (RWGS) reaction unit to produce an RWGS gas enriched in CO and water;

[0047] - Converting the RWGS gas in a Fischer-Tropsch reaction unit to produce a FT effluent;

[0048] - Optionally generating a first steam in the Fischer-Tropsch reaction unit to supply thermal energy to the carbon dioxide capture unit;

[0049] - Treating the FT effluent in a first separation unit to produce at least one hydrocarbon effluent, a first water effluent and a first gas effluent;

[0050] - Treating the first gas effluent in a second separation unit to produce a carbon dioxide-lean gas effluent and a carbon dioxide-rich gas effluent, and recycling the carbon dioxide-rich gas effluent to the inlet of the RWGS section;

[0051] - Optionally oxidizing at least a part of the carbon dioxide-lean gas effluent in an air combustion reaction unit, for example after expansion in a turbine, to produce a combustion effluent containing carbon dioxide and water;

[0052] - Optionally sending the combustion effluent to the carbon dioxide capture unit; and

[0053] - Treat the hydrocarbon effluent in a hydrogen reaction unit to produce at least one hydrocarbon fraction, e.g., meeting the specifications required for transportation applications.

[0054] According to one or more embodiments, the RWGS reaction unit comprises at least one reactor used under at least one of the following operating conditions:

[0055] - A temperature between 700 °C and 1200 °C, preferably between 800 °C and 1100 °C, more preferably between 850 °C and 1050 °C;

[0056] - A pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, more preferably between 0.1 MPa and 3.5 MPa;

[0057] - At 5000 NL / kg cata / h to 40000 NL / kg cata / h of the gas hourly space velocity at the reactor inlet;

[0058] - A catalyst comprising a metal or combination of metals selected from the group consisting of elements Ni, Cu, Fe, Co, Pt, Pd, Ru, Ag, and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises, for example, a support based on alumina, silica, silica-alumina, or silicoaluminate.

[0059] According to one or more embodiments, the FT reaction unit comprises at least one reactor used under at least one of the following operating conditions:

[0060] - A temperature between 170 °C and 280 °C, preferably between 190 °C and 260 °C, preferably between 210 °C and 240 °C;

[0061] - An absolute pressure between 0.1 MPa and 6.0 MPa, preferably between 1.5 MPa and 3.5 MPa, preferably between 2.0 MPa and 3.0 MPa;

[0062] - A catalyst comprising cobalt or iron, preferably cobalt, and optionally comprising, for example, a support based on alumina, silica, silica-alumina, silicoaluminate, or titanium.

[0063] According to one or more embodiments, the air combustion reaction unit comprises at least one reactor used under at least one of the following operating conditions:

[0064] - An absolute pressure between 0.1 MPa and 4 MPa;

[0065] - A temperature between 600 °C and 2000 °C, preferably between 800 °C and 1800 °C, more preferably between 900 °C and 1500 °C;

[0066] - There is air for combustion, which has an aeration rate between 1 and 2, preferably at least 1.2, where the aeration rate is defined as the molar flow rate of the injected air divided by the theoretical air flow rate required for complete oxidation of all fuels.

[0067] According to one or more embodiments, the second separation unit is a unit for separating carbon dioxide by means of a membrane and / or by absorption in a solvent and / or by adsorption on a solid.

[0068] When reading the following description, which is given only as a non - limiting example and with reference to the following drawings, embodiments of the apparatus and method according to the above aspects, as well as other features and advantages, will become apparent.

[0069] List of Drawings

[0070] Figure 1 A schematic diagram showing the apparatus according to the present invention, which includes a second separation unit for generating a carbon dioxide - rich gas effluent to be sent to the RWGS reaction unit.

[0071] Description of Embodiments

[0072] Embodiments of the apparatus according to the first aspect and the method according to the second aspect are now described in detail. In the following detailed description, many specific details are disclosed to provide a deeper understanding of the apparatus. However, it will be apparent to those skilled in the art that the apparatus can be used without these specific details. In other cases, well - known features are not described in detail to avoid unnecessarily complicating the description.

[0073] In this specification, the term "comprising" is synonymous with "including" and "containing" (having the same meaning), and is inclusive or open - ended, not excluding other unspecified elements. It is to be understood that the term "comprising" includes the exclusive and closed term "consisting of". Further, in this specification, an effluent that is essentially or only contains compound A corresponds to an effluent that contains at least 95 wt%, preferably at least 98 wt%, very preferably at least 99 wt% of compound A.

[0074] In this specification, the term "physical solvent" is synonymous with a solvent that forms weak bonds (such as hydrogen bonds, van der Waals bonds) with the solute or does not form strong bonds (such as covalent bonds, ionic bonds) with the solute.

[0075] The present invention can be defined as a device and method comprising a series of unit operations for producing synthetic hydrocarbons, preferably of very high quality, such as synthetic fuels, e.g. gasoline, kerosene, gas oil and / or naphtha or lubricant base oils, from carbon dioxide coming from a capture unit.

[0076] The device and method according to the invention are characterized in particular in that they comprise and use the following units: a carbon dioxide capture unit, a reverse water gas shift (RWGS) conversion unit, a Fischer-Tropsch (FT) synthesis unit and a unit for hydrogen treatment (hydrotreating and / or hydrocracking and / or hydroisomerization) of the hydrocarbon fraction from the FT reaction unit, a unit for separating carbon dioxide from the gaseous effluent obtained from the Fischer-Tropsch process and optionally a combustion unit for the gaseous hydrocarbon by-products of the process (RWGS and Fischer-Tropsch synthesis and post-treatment) after separation thereof. Advantageously, the hydrogen required can be produced by a water electrolysis unit, the water possibly originating from the RWGS and Fischer-Tropsch reaction units.

[0077] One of the features of the present invention can be summarized as the use of carbon dioxide to produce synthetic fuels, gasoline, kerosene, gas oil and / or naphtha or lubricant base oils of very high quality. The present invention is also based on the presence of a carbon dioxide separation unit for extracting and recycling carbon dioxide from the other gaseous hydrocarbon by-products of the process.

[0078] The air combustion unit can advantageously provide treatment of the carbon dioxide-lean gaseous hydrocarbon by-products to produce a carbon dioxide-rich gaseous effluent to improve the production of the product of interest.

[0079] Furthermore, the release of heat generated by combustion can advantageously be used to supply thermal energy to the RWGS reaction unit (8) and / or the carbon dioxide capture unit (2). This thermal energy input can be effected, for example, by heat exchange with:

[0080] - the combustion gases in the combustion chamber; and / or

[0081] - the high-temperature gaseous effluent downstream of the combustion chamber; and / or

[0082] - the steam generated by the air combustion reaction unit and / or by heat exchange with the gaseous combustion effluent.

[0083] According to one or more embodiments, the present invention also enables minimization of the amount of carbon energy external to the process and thus minimization of the environmental impact by virtue of an original energy integration based on the use of the thermal desorption of carbon dioxide (e.g. carbon dioxide complexed with amines in the carbon dioxide capture unit, more particularly in the solvent regeneration unit) at the outlet of the Fischer-Tropsch reaction unit and optionally the RWGS reaction unit.

[0084] According to one or more embodiments, electricity can also be generated by a turbine fed with the effluent and / or vapor from a Fischer-Tropsch reaction unit (e.g., generated at the outlet of a Fischer-Tropsch reaction unit and / or an RWGS reaction unit), and this electricity enables, for example, the supply of thermal energy to a device according to the invention, such as to an RWGS reaction unit.

[0085] Thus, the combination of a unit for capturing and chemically converting carbon dioxide with a preferably primary thermal integration enables the production of fuel bases, in particular for the aviation industry, while minimizing the environmental impact of the process.

[0086] Preferably, using a water electrolysis unit to treat the water produced by the RWGS reaction unit and / or the Fischer-Tropsch unit also enables the minimization of the environmental impact of the process.

[0087] Reference Figure 1 , a device for converting carbon dioxide into liquid hydrocarbons comprises:

[0088] - a carbon dioxide capture unit 2, which is adapted to treat a feedstock 1 containing carbon dioxide and produce a carbon dioxide-rich (gaseous) effluent 3 (i.e., enriched in carbon dioxide compared to the feedstock 1);

[0089] - a water electrolysis unit 5, which is adapted to treat water 4 (fresh or recycled) to produce oxygen 6 and hydrogen 7;

[0090] - an RWGS reaction unit 8, which is adapted to convert at least part of the carbon dioxide from the carbon dioxide-rich effluent 3 into an RWGS gas 9 rich in CO (i.e., a synthesis gas enriched in CO (and water) compared to the carbon dioxide-rich effluent 3);

[0091] - a Fischer-Tropsch (FT) reaction unit 13, which is adapted to convert the RWGS gas 9 and produce a Fischer-Tropsch (FT) effluent 14, and optionally adapted to generate a first steam 22, which is generated, for example, by vaporizing water in an exchanger located within the FT reaction unit 13, to supply thermal energy to the carbon dioxide capture unit 2;

[0092] - a first separation unit 15, which is adapted to at least partially treat the FT effluent 14 and produce: at least a hydrocarbon effluent 17, a first gas effluent 33 (exhaust gas), and a first water effluent 16, i.e., the product of Fischer-Tropsch synthesis obtained by condensation of gaseous water under the operating conditions of the Fischer-Tropsch reaction;

[0093] - a second separation unit 34, which is used to produce a carbon dioxide-lean gas effluent 18 and a carbon dioxide-rich gas effluent 35 from the first gas effluent 33 and recycle the carbon dioxide-rich gas effluent 35 to the inlet of the RWGS section 8;

[0094] - Optionally, an air combustion reaction unit 28, which is adapted to oxidize at least a portion 24 of the carbon dioxide-lean gas effluent 18 separated by the second separation unit 34 to produce a combustion effluent 29 comprising carbon dioxide and water, and to send the combustion effluent 29 to the carbon dioxide capture unit 2;

[0095] - A hydrogen reaction unit 20 (hydrotreating and / or hydrocracking and / or hydroisomerization unit), which is adapted to treat the hydrocarbon effluent 17 with hydrogen 7 and separate at least one hydrocarbon fraction 21, which comprises at least one of the following fractions, for example: naphtha, gasoline, kerosene, gas oil, and lubricant base stock;

[0096] - Optionally, at least one heat exchanger 31, which is adapted to generate a second steam 23 by heat exchange between water and the RWGS gas 9, which can supply heat energy to the carbon dioxide capture unit 2, for example; and

[0097] - Preferably, a separation unit 10, which is adapted to treat the RWGS gas 9 to produce a water-lean RWGS gas 12 (compared to the RWGS gas 9), send it instead of the RWGS gas 9 to the FT reaction unit 13, and send the second water effluent 11 to the water electrolysis unit 5.

[0098] Advantageously, the FT reaction unit 13 and the optional first heat exchanger 31 are adapted to generate steam by heat exchange. Advantageously, the use of steam enables energy to be supplied to the carbon dioxide capture unit 2, for example by regenerating an amine-based (or physical solvent) carbon dioxide-carrying solvent in the regeneration unit of the carbon dioxide capture unit 2 or by feeding a temperature swing adsorption device.

[0099] To avoid unnecessarily complicating the description and the drawings, it is obvious to a person skilled in the art that the water supply of the FT reaction unit 13 and the heat exchanger 31 for generating steam is not described in detail. The same applies to the water outlet of the carbon dioxide capture unit 2.

[0100] Carbon dioxide capture unit

[0101] The carbon dioxide capture unit 2 enables carbon dioxide to be separated from the rest of the feedstock 1. Such a carbon dioxide capture unit conventionally enables CO2 to be supplied, which can be compressed for upgrading or storage. According to one or more embodiments, the feedstock 1 comprises at least 0.04% by volume of carbon dioxide, preferably at least 2% by volume of carbon dioxide, and very preferably at least 10% by volume of carbon dioxide.

[0102] According to one or more embodiments, feedstock 1 comprises or consists of combustion flue gas. According to one or more embodiments, feedstock 1 comprises a gaseous effluent from at least one unit selected from a refinery, an incinerator, a petrochemical unit, a chemical unit, a thermal power plant, a paper mill, an ethanol plant, and a sugar refinery. According to one or more embodiments, feedstock 1 comprises a gaseous effluent from a cement plant, and / or a gaseous effluent from a lime production unit, and / or a gaseous effluent from a blast furnace. According to one or more embodiments, the combustion flue gas is derived from a combustion chamber (such as a boiler) designed to burn a fuel (such as coal, natural gas, fuel oil, biogas, biomass, organic waste, municipal waste) with an oxidizer (usually air).

[0103] According to one or more embodiments, feedstock 1 comprises or consists of biogas, natural gas, syngas, refinery gas, biomass fermentation gas, cement plant gas, and / or blast furnace gas.

[0104] The carbon dioxide may also be the carbon dioxide present in air. According to one or more embodiments, feedstock 1 comprises or consists of air. For example, the carbon dioxide capture unit 2 may include a direct air capture (DAC) device.

[0105] For capture, several reagents such as solvents and solids can be used. According to the present invention, the carbon dioxide capture unit 2 uses at least one amine-based solvent and / or at least one physical solvent such as based on polyethylene glycol dimethyl ether, and / or a temperature swing adsorption (physical adsorption) device.

[0106] A common carbon dioxide capture technique is based on the absorption phenomenon, i.e., the transfer of chemical species from a gas to a liquid. The gas containing impurities or the species to be separated is sent to a column where it is brought into contact with a liquid solvent, and these two streams can be used in various hydrodynamic configurations (cocurrent, crosscurrent, or countercurrent, and the latter solution is preferred due to the favorable thermodynamic equilibrium). This absorption is carried out using an absorbent solution comprising a chemical solvent or a physical solvent, and this distinction is related to whether there is a chemical reaction between the component to be absorbed and the solvent.

[0107] To minimize the energy cost of the method, physical absorption is preferred; this is particularly suitable in the case of a high partial pressure of the species to be separated.

[0108] Chemical absorption is preferred in the case of high dilution and low partial pressure of the class of substances to be separated and / or in the case where a high recovery rate of this class of substances is required, or finally, if strict specifications regarding the maximum allowable concentration of this class of substances in the washed gas stream are to be achieved. Thus, in order to capture carbon dioxide from (industrial) flue gas having a low carbon dioxide concentration value typically between 3 vol% and 15 vol% (usually in low-pressure gas), washing by chemical absorption, for example using an amine solvent, such as an alkanolamine-type amine solvent, is very suitable.

[0109] Currently commonly used absorbent solutions are aqueous solutions containing one or more reactive compounds or compounds having physicochemical affinity with acidic compounds. Reactive compounds can be, for example but not limited to, amines (primary amines, secondary amines, tertiary amines, cyclic or acyclic amines, aromatic or non-aromatic amines, saturated or unsaturated amines), alkanolamines, polyamines, amino acids, alkali metal salts of amino acids, amides, ureas, phosphates, carbonates or borates of alkali metals. According to one or more embodiments, the absorbent solution is an aqueous solution containing one or more reactive compounds having amine functional groups, the structure of which is described on page 6, line 1 to page 7, line 3 of patent application WO2007 / 104856.

[0110] According to one or more embodiments, the reactive compounds constitute 10 wt% to 90 wt%, preferably between 20 wt% and 50 wt%, very preferably between 25 wt% and 40 wt% of the total weight of the absorbent solution.

[0111] Chemical absorption in amine solvents is based on acid-base equilibrium. Low temperature promotes the reaction between basic amines and acidic carbon dioxide, and high temperature promotes the reverse reaction. Thus, an amine process using, for example, an aqueous phase containing 20 - 50 wt% amine can use two towers (not shown), where the solvent is circulated from one tower to the other. In the first tower, called the absorber, the stream to be washed (i.e., feedstock 1) is brought into contact with the amine solvent at low temperature. The amine solvent flows into this tower and captures carbon dioxide. At the bottom of the tower, the amine solvent ("rich" solvent) reaches a predetermined loading rate, i.e., the ratio between the number of moles of captured carbon dioxide and the number of moles of amine; at the top of the tower, the gas stream itself leaves with a predetermined specification, i.e., the carbon dioxide content is, for example, close to 1 / 10 times the initial content in the flue gas. The rich solvent is sent to the second tower, called the regenerator, which operates similarly to a distillation tower operating at high temperature. The regenerated amine solvent ("lean" solvent) itself can be sent back to the absorber. The amine solvent thus continuously circulates from one tower to the other in a closed loop, preferably through a feedstock / effluent heat exchanger, to cool the lean solvent and preheat the rich solvent, while saving energy throughout the process.

[0112] According to one or more embodiments, the regenerator operates at a high temperature between 90°C and 250°C, preferably between 110°C and 240°C, and very preferably between 120°C and 200°C, at the bottom of the column.

[0113] The carbon dioxide released from the regenerator can then optionally be compressed and upgraded. According to one or more embodiments, the carbon dioxide-rich effluent 3 contains at least 90 vol% carbon dioxide, preferably at least 95 vol% carbon dioxide, and very preferably at least 98 vol% carbon dioxide. According to one or more embodiments, the carbon dioxide-rich effluent 3 has a temperature between 20°C and 250°C, preferably between 30°C and 200°C, and very preferably between 40°C and 150°C when leaving the carbon dioxide capture unit 2. According to one or more embodiments, the carbon dioxide-rich effluent 3 has a pressure between 0.20 MPa and 4 MPa, preferably between 0.30 MPa and 3.5 MPa, and very preferably between 0.4 MPa and 3 MPa when leaving the carbon dioxide capture unit 2.

[0114] One fundamental aspect of the solvent treatment operation of industrial flue gas is the regeneration step of the separation agent. Depending on the type of absorption (physical and / or chemical), regeneration is generally envisaged by expansion and / or by distillation and / or by entrainment with a vaporizing gas called "stripping gas".

[0115] One of the main limitations of currently commonly used solvents is the need to use a high flow rate of absorbent solution, which results in high energy consumption for solvent regeneration and large sizes of equipment (columns, pumps, etc.). This is especially the case when the partial pressure of carbon dioxide is low. Such energy consumption represents a significant operating cost of the carbon dioxide capture method. The regeneration energy depends on the nature of the amine and the partial pressure of carbon dioxide, and is generally 2 GJ / t to 4 GJ / t of captured carbon dioxide. New capture methods tend to reduce this energy in order to tend towards values below 2 GJ / t of carbon dioxide. In the case of air treatment, due to the very low carbon dioxide concentration, the energy consumed is very high, approximately 5 GJ / t of carbon dioxide to 7.5 GJ / t of carbon dioxide.

[0116] Another possible implementation is based on the adsorption principle using solid adsorbents with a strong chemical affinity for carbon dioxide. To ensure a continuous operating mode, the method operates with several reactors in parallel. Carbon dioxide is adsorbed on the solid adsorbent and the treated stream (i.e., the feedstock 1) becomes depleted as it progresses through the solid bed, and at the outlet, this stream no longer contains or hardly contains any carbon dioxide. However, the solid adsorbent gradually becomes saturated and can no longer adsorb carbon dioxide. Then the stream to be treated is sent to another reactor containing a solid adsorbent not saturated with carbon dioxide, and the capture operation continues. At the same time, the reactor saturated with carbon dioxide undergoes a regeneration operation:

[0117] – An increase in temperature is referred to as temperature swing adsorption (TSA); and

[0118] – A partial vacuum is referred to as pressure swing adsorption (or VPSA, i.e., vacuum pressure swing adsorption, or simply VSA or PSA, optionally in the presence of a gas that promotes desorption).

[0119] The obstacle of the TSA process is the large amount of heat required for regeneration. The heat integration proposed in the present invention enables this obstacle to be eliminated.

[0120] According to one or more embodiments, the solid adsorbents for carbon dioxide capture are selected from the following compounds: activated carbon, zeolite, alumina, silica, synthetic fibers with or without impregnated amines, metal-organic framework (MOF) solids, and supported alkali metal carbonates. These solid absorbents are increasingly used for capturing carbon dioxide from air. In these cases, the regeneration energy for adsorbents with physical adsorption, such as on zeolite, is approximately 0.6 to 0.9 GJ / t of carbon dioxide. For solid supported amines, the regeneration energy is 5.4 to 7.2 GJ / t of carbon dioxide.

[0121] Advantageously, the energy required for the regeneration of the amine solvent and / or the increase in temperature of the solid adsorbent can be provided at least in part by the first steam 22 and optionally the second steam 23. This energy input to the carbon dioxide capture unit 2 enables the energy efficiency of the method to be maximized.

[0122] According to one or more embodiments, the temperature of the steam 22 and / or 23 is at least 110 °C, preferably at least 120 °C, very preferably at least 130 °C, for example at the outlet of the heat exchanger 31 and / or the FT reaction unit 13. According to one or more embodiments, the temperature of the steam 22 and / or 23 is between 110 °C and 270 °C, preferably between 120 °C and 260 °C, very preferably between 130 °C and 220 °C, for example at the outlet of the heat exchanger 31 and / or the FT reaction unit 13. According to one or more embodiments, the steam 22 and / or 23 has a pressure between 0.1 MPa and 4 MPa, preferably between 0.1 MPa and 3.5 MPa, very preferably between 0.1 MPa and 1.7 MPa, for example at the outlet of the heat exchanger 31 and / or the FT reaction unit 13.

[0123] Water electrolysis unit

[0124] The water electrolysis unit 5 processes the water 4 from the make-up line and / or from the optional third separation unit 10 and / or from the first separation unit 15.

[0125] According to one or more embodiments, the water electrolysis unit 5 includes a pretreatment section adapted to extract oxygen-containing compounds from the water 4, such as from the first water effluent 16.

[0126] According to one or more embodiments, the water electrolysis unit 5 comprises at least one alkaline electrolyzer. Other electrolyzer technologies can be used for the water electrolysis unit, such as proton exchange membrane (PEM) electrolysis, solid oxide electrolysis (SOE), or anion exchange membrane (AEM) electrolysis. The operating conditions (temperature, pressure, electrolyte, nature of the electrodes and diaphragm / membrane) are thus specific to each technology.

[0127] According to one or more embodiments, the water electrolysis unit 5 comprises at least one reactor used under at least one of the following operating conditions:

[0128] Alkaline electrolyzer:

[0129] - A temperature between 60 °C and 90 °C,

[0130] - A pressure between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 4 MPa

[0131] - An electrolyte containing KOH,

[0132] - Electrodes containing a metal alloy,

[0133] - A diaphragm containing asbestos, polytetrafluoroethylene, and / or nickel oxide;

[0134] Proton exchange membrane (PEM) electrolyzer:

[0135] - A temperature between 50 °C and 80 °C,

[0136] - A pressure between 0.1 MPa and 20 MPa, preferably between 1.8 MPa and 5.5 MPa,

[0137] - An electrolyte containing a polymer membrane,

[0138] - Electrodes containing a metal alloy;

[0139] Solid oxide electrolyzer (SOE):

[0140] - A temperature between 800 °C and 900 °C,

[0141] - A pressure between 0.1 MPa and 2 MPa, preferably between 0.1 MPa and 0.5 MPa,

[0142] - An electrolyte containing a ceramic (e.g., perovskite) membrane,

[0143] - Electrodes containing a metal alloy;

[0144] Anion exchange membrane (AEM) electrolyzer:

[0145] - A temperature between 50 °C and 70 °C,

[0146] - A pressure between 0.1 MPa and 20 MPa, preferably between 0.1 MPa and 3.5 MPa,

[0147] - An electrolyte containing a polymer membrane,

[0148] - An electrode containing a metal alloy.

[0149] According to one or more embodiments, the oxygen 6 produced by the water electrolysis unit 5 contains O2 between 99.0 wt% and 99.8 wt% (after drying).

[0150] According to one or more embodiments, the hydrogen 7 produced by the water electrolysis unit 5 contains H2 between 99.5 wt% and 99.999 wt% (after drying).

[0151] According to one or more embodiments, the water electrolysis unit 5 is based on solid oxide electrolyzer (SOE) technology, where at least a portion of the water 4 can be in the form of steam supplied at least in part by the first steam 22 and optionally by the second steam 23. This energy supply to the electrolysis unit 5 enables improvement of the energy efficiency of the method.

[0152] RWGS reaction unit

[0153] The RWGS reaction unit 8 produces RWGS gas 9 (syngas), which is enriched in CO (and depleted in hydrogen) compared to the carbon dioxide-rich effluent 3 and 35 containing unreacted carbon dioxide and water. The hydrogen 7 required for the RWGS reaction comes from the water electrolysis unit 5.

[0154] According to one or more embodiments, the RWGS reaction unit 8 comprises at least one reactor used under at least one of the following operating conditions:

[0155] - A temperature between 700 °C and 1200 °C, preferably between 800 °C and 1100 °C, more preferably between 850 °C and 1050 °C;

[0156] - A pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, more preferably between 0.1 MPa and 3.5 MPa;

[0157] - At 5000 NL / kg cata / h to 40000 NL / kg cata / h of the gas space velocity at the reactor inlet;

[0158] - Catalysts based on the elements Ni, Cu, Fe, Co or noble metals such as Pt, Pd, Ru, Ag and Au. According to one or more embodiments, the catalyst for the RWGS reaction comprises a support based on, for example, alumina, silica, silica-alumina or silicoalumina.

[0159] According to one or more embodiments, the amount of hydrogen at the inlet of the RWGS reaction unit 8 is adjusted so that the H2 / CO molar ratio at the outlet of the RWGS reaction unit 8 is compatible with the requirements of the FT unit, i.e., between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5.

[0160] According to one or more embodiments, the RWGS gas 9 has a temperature at the outlet of the RWGS reaction unit 8 of at least 700 °C, preferably at least 750 °C, very preferably at least 800 °C.

[0161] In one or more embodiments, at least a portion of the RWGS gas 9 supplies energy to the regeneration unit of the carbon dioxide capture unit 2 by means of a first heat exchanger 31, which generates a second steam 23 by (indirect) heat exchange between water (not shown) and the RWGS gas 9, preferably directly at the outlet of the RWGS reaction unit 8.

[0162] Preferably, the RWGS gas 9 is sent to a third separation unit 10.

[0163] Fischer-Tropsch reaction unit

[0164] According to the present invention, in the FT reaction unit 13, carbon monoxide and hydrogen present in the RWGS gas 9 (preferably water-lean) react to produce a stream comprising a FT effluent 14, which comprises unreacted syngas, carbon dioxide, gaseous and liquid hydrocarbon products and water.

[0165] According to one or more embodiments, the RWGS gas 9 (preferably water-lean) sent to the FT reaction unit 13 comprises carbon monoxide and hydrogen, wherein the H2 / CO molar ratio is between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5. According to one or more embodiments, the amount of hydrogen upstream (e.g., at the inlet) of the FT reaction unit 13 is adjusted, for example, by means of an optional hydrogen supply, so that the H2 / CO molar ratio is as defined above.

[0166] The FT reaction unit 13 is used in a reaction unit comprising one or more suitable reactors, the technology of which is known to those skilled in the art. This can be, for example, one or more multitubular fixed bed reactors, or one or more slurry bubble column reactors, or one or more microchannel reactors.

[0167] According to one or more embodiments, the FT reaction unit uses one or more bubble column reactors. Since the synthesis is highly exothermic, this embodiment is particularly capable of improving the thermal control of the reactor and causing only a very small pressure drop.

[0168] The catalyst used in this Fischer-Tropsch synthesis is generally any catalyst solid known to those skilled in the art for carrying out Fischer-Tropsch synthesis. According to one or more embodiments, the catalyst used in the Fischer-Tropsch synthesis contains cobalt or iron, preferably cobalt. The catalyst used is generally a supported catalyst. The support can be, for example, based on alumina, silica, silica-alumina, siliceous alumina or titanium.

[0169] According to one or more embodiments, the FT reaction unit 13 includes at least one reactor used under at least one of the following operating conditions:

[0170] - A temperature between 170 °C and 280 °C, preferably between 190 °C and 260 °C, more preferably between 210 °C and 240 °C,

[0171] - An absolute pressure between 0.1 MPa and 6.0 MPa, preferably between 1.5 MPa and 3.5 MPa, more preferably between 2.0 MPa and 3.0 MPa.

[0172] The FT effluent 14 is sent to the first separation unit 15. According to one or more embodiments, the FT effluent 14 has a temperature at the outlet of the FT reaction unit 13 of at least 170 °C, preferably at least 190 °C, and very preferably at least 210 °C.

[0173] According to one or more embodiments, the FT reaction unit 13 is adapted to generate a first steam 22 and supply thermal energy to the carbon dioxide capture unit 2. The first steam 22 is generated, for example, by vaporizing water (not shown) in a heat exchanger located within the FT reaction unit 13 so as to be able to remove the thermal energy from the Fischer-Tropsch reaction (which is an exothermic reaction).

[0174] First separation unit

[0175] In the first separation unit 15, at least one (first) portion of the FT effluent 14 is processed to produce:

[0176] - A hydrocarbon effluent 17 (lean in water compared to the FT effluent 14),

[0177] - A first gas effluent 33, and

[0178] - A first water effluent 16.

[0179] According to one or more embodiments, a second portion of the FT effluent 14 is sent directly to the hydrogen reaction unit 20. Preferably, the second portion of the FT effluent 14 is a liquid portion, preferably containing little or no water.

[0180] At the outlet of the first separation unit 15, the hydrocarbon effluent 17 is sent to the hydrogen reaction unit 20, and optionally the first water effluent 16 is sent to the water electrolysis unit 5 via the first recycle line.

[0181] According to one or more embodiments, the hydrocarbon effluent 17 comprises: normal paraffins, olefins and oxygenates produced by the condensation of gaseous hydrocarbons under the operating conditions of the Fischer-Tropsch reaction.

[0182] According to one or more embodiments, the hydrocarbon effluent 17 contains less than 5 wt% water, preferably less than 2 wt% water, and very preferably less than 1 wt% water.

[0183] According to one or more embodiments, the first water effluent 16 is produced by Fischer-Tropsch synthesis, which is produced by the condensation of gaseous water under the operating conditions of the Fischer-Tropsch reaction.

[0184] According to one or more embodiments, the first gas effluent 33 contains unreacted syngas, carbon dioxide and gaseous hydrocarbons such as (mainly) C1 to C4 paraffins, C2 to C4 olefins and C1 to C3 oxygenates.

[0185] Second separation unit

[0186] In the second separation unit 34, the first effluent 33 from the first separation unit 15 is processed to produce:

[0187] - a carbon dioxide-lean gas effluent 18; and

[0188] - a carbon dioxide-rich gas effluent 35 that is rich in carbon dioxide relative to the carbon dioxide content of the first gas effluent 33.

[0189] According to the first embodiment, the second separation unit 34 is a membrane separation unit. Membrane separation processes were not initially recommended for post-combustion carbon dioxide capture, and gas-liquid absorption processes in chemical solvents were considered the most mature and suitable technologies for performing this operation. However, recent technologies have made it possible to economically separate carbon dioxide using membranes (dense polymers, inorganic materials, hybrid matrices, liquid membranes). Reference can be made to the review article: Oil Gas Sci. Technol.–Rev. IFP Energies nouvelles, Vol. 69, No. 6, November–December 2014. The main performance is a capture rate and a carbon dioxide purity of greater than 90%.

[0190] According to a second embodiment, the second separation unit 34 is a carbon dioxide capture unit based on the absorption of carbon dioxide in a solvent.

[0191] According to a third embodiment, the second separation unit 34 is a carbon dioxide capture unit based on the adsorption of carbon dioxide on a solid.

[0192] According to one or more embodiments, a (first) portion 19 of the carbon dioxide-lean gas effluent 18 is sent via a second recycle line to the FT reaction unit 13.

[0193] According to one or more embodiments, at least a (second) portion 24 of the carbon dioxide-lean gas effluent 18 is processed by a first turbine 26 to generate electricity, and the gas 27 leaving the first turbine 26 is sent to the air combustion reaction unit 28.

[0194] According to one or more embodiments, a (third) portion of the carbon dioxide-lean gas effluent 18 is recycled to the RWGS reaction unit 8 (not shown) to convert it into syngas and thereby improve the mass yield of the production line.

[0195] According to one or more embodiments, a (fourth) portion of the carbon dioxide-lean gas effluent 18 is sent to a separate syngas production unit (not shown) of, for example, the following types:

[0196] - partial oxidation (or POx);

[0197] - steam methane reforming (or SMR);

[0198] - autothermal reforming (or ATR);

[0199] - enhanced heat transfer reforming (or EHTR).

[0200] According to one or more embodiments, the syngas produced in the separate unit is recycled to the inlet or outlet of the RWGS reaction unit 8.

[0201] Air combustion reaction unit

[0202] According to one or more embodiments, at least a portion 24 of the carbon dioxide-lean gas effluent 18 is sent to the air combustion reaction unit 28, where the hydrocarbon compounds, carbon monoxide, and hydrogen present therein (i.e., CO, H2, alkanes and alkenes having 1 to 7 carbon atoms per molecule, and alcohol compounds having 1 to 3 carbon atoms per molecule) are at least partially converted into carbon dioxide and water in the presence of air 30 to produce a combustion gas (e.g., substantially) containing carbon dioxide and water.

[0203] According to one or more embodiments, the air combustion reaction unit 28 comprises at least one reactor used under at least one of the following operating conditions:

[0204] - An absolute pressure between 0.1 MPa and 4 MPa;

[0205] - A temperature between 600 °C and 2000 °C, preferably between 800 °C and 1800 °C; preferably between 900 °C and 1500 °C;

[0206] - There is air 30 having an aeration rate between 1 and 2, preferably at least 1.2, especially to limit the concentration of unburned CO and H2 gases.

[0207] The aeration rate is defined as the ratio of the molar flow rate of the injected air to the theoretical air flow rate required for complete oxidation of all fuels.

[0208] According to one or more embodiments, at least a portion of the "light" hydrocarbon fraction (not shown) obtained from the hydrogen reaction unit 20 is sent to the air combustion reaction unit 28 (not shown). According to one or more embodiments, the hydrocarbon fraction comprises gaseous hydrocarbons such as (primarily) C1 to C4 alkanes, C2 to C4 olefins, and C1 to C3 oxygenates.

[0209] According to one or more embodiments, the combustion gas produced in the air combustion reaction unit 28 has a temperature between 600 °C and 2000 °C, preferably between 800 °C and 1800 °C, preferably between 900 °C and 1500 °C, and an absolute pressure between 0.1 MPa and 4 MPa.

[0210] The combustion gas produced in the air combustion reaction unit 28 is at a high temperature such that a portion of the thermal energy required to supply the RWGS reaction unit 8 and / or the carbon dioxide capture unit 2 via the feed line 32 can be provided.

[0211] According to one or more embodiments, the air combustion reaction unit 28 is adapted to generate heat for supplying thermal energy to the RWGS reaction unit 8 and / or the carbon dioxide capture unit 2 (via the feed line 32), for example, by heat exchange to heat the carbon dioxide-rich effluent 3 and / or the carbon dioxide-rich gas effluent 35 and / or the hydrogen 7, or by integrating the reaction section of the RWGS reaction unit 8 into the chamber of the air combustion unit 28.

[0212] The heat energy can be provided by heat exchange with, for example, the steam generated by the air combustion reaction unit 28 and / or in the combustion chamber of the air combustion reaction unit 28 and / or with the high-temperature gas effluent downstream of the air combustion reaction unit 28. For example, after transferring the heat energy from the combustion gas in the combustion chamber to, for example, the RWGS reaction 8, the waste heat contained in the combustion effluent 29 at the outlet of the air combustion reaction unit 28 can be used to generate steam, for example, sent to the carbon dioxide capture unit 2.

[0213] The input of heat energy can be carried out, for example, by heat exchange with the steam generated by the partial oxy-fuel combustion reaction unit 28 and / or heat exchange in the oxy-fuel combustion chamber of the partial oxy-fuel combustion reaction unit 28.

[0214] Advantageously, the air combustion reaction unit 28 makes it possible to convert substantially all hydrocarbon by-products of the process into carbon dioxide and thus upgrade them in the form of the desired product. Therefore, the yield of the desired product of the method according to the present invention is improved.

[0215] Recycle the combustion effluent 29 at the outlet of the air combustion reaction unit 28 to the inlet of the carbon dioxide capture unit 2.

[0216] Hydrogen reaction unit

[0217] Send the hydrocarbon effluent 17 to the hydrogen reaction unit 20 for hydrotreating and / or hydrocracking and / or hydroisomerization reactions, where one or more hydrocarbon fractions 21 can be upgraded, especially very high-quality (substantially sulfur-free, aromatic-free, nitrogen-free) synthetic fuels, namely gasoline, kerosene, gas oil, and / or other hydrocarbon products such as naphtha or lubricant base oil. One possible option is to produce paraffinic fractions, the basic products of the petrochemical process, for example, to produce C10-C13 fractions intended for the production of linear alkylbenzenes (LAB), or waxes for various industrial applications.

[0218] According to one or more embodiments, the hydrogen reaction unit 20 comprises at least one reactor used under at least one of the following operating conditions:

[0219] - A temperature between 250 °C and 450 °C, more preferably between 280 °C and 450 °C, even more preferably between 320 °C and 420 °C;

[0220] - A pressure between 0.2 MPa and 15 MPa, preferably between 0.5 MPa and 12 MPa, more preferably between 1 MPa and 10 MPa;

[0221] - Between 0.1 h -1 and 10 h -1 preferably between 0.2 h -1 and 7 h -1between, more preferably between 0.5 h -1 and 5 h -1 The space velocity between is defined as the ratio of the volume flow rate of the feedstock at ambient temperature and pressure to the volume of the catalyst;

[0222] - A hydrogen flow rate between 100 and 2000 standard liters of hydrogen / liter of feedstock / hour, preferably between 150 and 1500 standard liters of hydrogen / liter of feedstock, more preferably between 300 and 1500 standard liters of hydrogen / liter of feedstock.

[0223] According to one or more embodiments, the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one hydrogenation-dehydrogenation metal selected from Group VIB and Group VIIIB metals of the periodic table and at least one solid that is a Bronsted acid, i.e., a solid capable of releasing one or more protons, and optionally a binder.

[0224] According to one or more embodiments, the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one Group VIIIB noble metal selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum, either alone or as a mixture, preferably selected from platinum and palladium, either alone or as a mixture, and preferably used in their reduced form.

[0225] According to one or more embodiments, the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises: at least one metal selected from nickel, molybdenum, tungsten, cobalt, ruthenium, indium, palladium, and platinum; at least one support selected from alumina, boron oxide, magnesia, zirconia, titania, and clay. According to one or more embodiments, the support is alumina, silica-alumina, siliceous alumina, or silica.

[0226] According to one or more embodiments, the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one Group VIIIB base metal selected from nickel and cobalt in combination with at least one Group VIB metal selected from molybdenum and tungsten, which are used either alone or as a mixture, and preferably used in their sulfide form.

[0227] According to one or more embodiments, in the case where the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one Group VIIIB noble metal, based on the total weight of the catalyst, the noble metal content in the catalyst is between 0.01 wt% and 5 wt%, preferably between 0.05 wt% and 4 wt%, very preferably between 0.10 wt% and 2 wt%.

[0228] According to one or more embodiments, in the case where the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one Group VIB metal in combination with at least one Group VIII non-noble metal selected from nickel and cobalt, based on the total weight of the catalyst, the content of the Group VIB metal in the catalyst is between 5% by weight and 40% by weight in terms of oxide equivalent, preferably between 10% by weight and 35% by weight, and the content of the Group VIIIB metal in the catalyst is between 0.5% by weight and 15% by weight in terms of oxide equivalent, preferably between 1% by weight and 10% by weight, preferably between 1% by weight and 8% by weight, and very preferably between 1.5% by weight and 6% by weight.

[0229] According to one or more embodiments, the hydrotreating and / or hydrocracking and / or hydroisomerization catalyst comprises at least one noble metal and a support or consists of at least one noble metal and a support, and the support comprises at least one zeolite and at least one binder or consists of at least one zeolite and at least one binder.

[0230] According to one or more embodiments, the zeolite-based hydrotreating and / or hydrocracking and / or hydroisomerization catalyst is advantageously of the bifunctional type, i.e., it has a hydrogenation-dehydrogenation function and a hydroisomerization function.

[0231] Third separation unit

[0232] In the third separation unit 10, the RWGS gas 9 is treated, for example, by condensation to produce a water-lean RWGS gas 12 (compared to the RWGS gas 9), and the second water effluent 11 is recycled, for example, to the water electrolysis unit 5.

[0233] According to one or more embodiments, the water-lean RWGS gas 12 contains less than 1 mol% of water, preferably less than 0.5 mol% of water, and very preferably less than 0.25 mol% of water.

[0234] The water-lean RWGS gas 12 is sent to the FT reaction unit 13.

[0235] Turbine

[0236] Reference Figure 1 , according to one or more embodiments, the present invention enables the recovery of energy in the form of electricity by means of at least one turbine 26.

[0237] According to one or more embodiments, the first turbine 26 is adapted to process at least a portion 24 of the gas effluent 18 depleted in carbon dioxide to generate electricity.

[0238] According to one or more embodiments, a second turbine (not shown) is adapted to at least partially process the first steam 22 and / or the second steam 23 to generate electricity (not shown).

[0239] According to one or more embodiments, the electricity is used to supply heat energy to the RWGS reaction unit 8 and / or to the carbon dioxide capture unit 2 and / or to the water electrolysis unit 5. According to one or more embodiments, the electricity 25 is used to supply heat energy to the RWGS reaction unit 8. According to one or more embodiments, the electricity 25 can be used to drive an electric furnace for preheating the feedstock of the RWGS reaction unit 8.

[0240] Carbon dioxide separation unit

[0241] According to one or more embodiments, the apparatus further comprises a unit for separating carbon dioxide and optionally methane (not shown) (a compound that may be present in the RWGS gas 9). Advantageously, the carbon dioxide can be recycled into the RWGS reaction unit 8.

[0242] According to one or more embodiments, the carbon dioxide separation unit is arranged between the RWGS reaction unit 8 and the FT reaction unit 13. Advantageously, the size of the FT reaction unit 13 can thereby be reduced.

[0243] According to one or more embodiments, the carbon dioxide separation unit is arranged at the outlet of the FT reaction unit 13.

[0244] Oxy-fuel combustion unit

[0245] According to one or more embodiments, the oxygen 6 obtained from the water electrolysis unit is upgraded in an oxy-fuel combustion (partial or complete oxidation) unit, for example to convert the formed methane present in the RWGS gas 9 separated by the carbon dioxide separation unit.

[0246] Effluent purification unit

[0247] According to one or more embodiments, the carbon dioxide-rich effluent 3 and / or the carbon dioxide-rich gas effluent 35 are purified either separately or after mixing before being introduced into the RWGS reaction unit 8. According to one or more embodiments, the RWGS gas 9 is purified either upstream or downstream of the third separation unit 10 before being introduced into the FT reaction unit 13. According to one or more embodiments, the first water effluent 16 is purified before being introduced into the water electrolysis unit 5. The effluent purification step aims to at least partially remove sulfur-containing compounds and nitrogen-containing compounds, halogens, heavy metals and transition metals. The main techniques for purifying gases are: adsorption, absorption, catalytic reaction.

[0248] In this patent application, the groups of chemical elements are by default given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIIIB according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification; Group VIB according to the CAS classification corresponds to the metals in column 6 according to the new IUPAC classification. Examples

[0249] The various examples relate to sequences according to or not according to the invention, with the aim of producing hydrocarbon fractions from flue gas containing 21% by weight of carbon dioxide. For all examples, the flow rate of the flue gas to be treated is 3641 kg / h.

[0250] Example 1 not according to the invention

[0251] The example of the device not according to the invention is similar to the Figure 1 device shown, except that there is no second separation unit 34, so no carbon dioxide-rich gas effluent 35 is directed to the RWGS reaction unit 8.

[0252] This example illustrates the operation of a sequence having a part 24 of the carbon dioxide-lean gas effluent 18 from the first separation unit 15 with a combustion step upgraded to generate heat for the RWGS reaction unit 8. The carbon dioxide present in the carbon dioxide-lean gas effluent 18 is not separated before entering the air combustion reaction unit 28.

[0253] The flow rate of the flue gas fed to the carbon dioxide capture unit 2 is 3641 kg / h, to which the flow rate of the flue gas of the combustion effluent 29 must be added, which gives a total flow rate of the feedstock 1 of 5332 kg / h. The flow rate of the carbon dioxide-rich effluent 3 from the carbon dioxide capture unit 2 is 1283 kg / h and is sent to the RWGS reaction unit 8.

[0254] 1331 kg / h of water 4 is supplied to the water electrolysis unit 5, of which 672 kg / h is fresh water. The power consumption of the water electrolysis unit 5 is 5.8 MWe.

[0255] The amount of the first steam 22 generated by the FT reaction unit 13 is 1310 kg / h. Among the 2103 kg / h required for the operation of the carbon dioxide capture unit 2, the heat exchanger 31 generates 1295 kg / h of the second steam 23. The steam demand of the reboiler of the carbon dioxide capture unit 2 is covered.

[0256] The production rate of the hydrocarbon fraction 21 is 177 kg / h.

[0257] Table 1 summarizes the flow rates at the inlet and outlet of the process units.

[0258] Table 1

[0259]

[0260] Requirements:

[0261] - Consumption of the water electrolysis unit 5: 5.8 MWe;

[0262] - Heat consumed by the RWGS reaction unit 8 at 864 °C: 0.2 MWth;

[0263] - Heat required to preheat the feedstock (3 + 7) at the inlet of unit 8 to 864 °C: 0.8 MWth;

[0264] - Steam sent to the reboiler of the carbon dioxide capture unit 2: 2103 kg / h;

[0265] Energy recovery:

[0266] - Heat released by the air combustion reaction unit 28 at 1200 °C (with 20% excess air): 0.35 MWth;

[0267] - Heat recovered during the cooling of the flue gas from 1200 °C to 150 °C at the outlet of the air combustion reaction unit 28: 0.7 MWth (for preheating the feedstock (3 + 7) at the inlet of unit 8);

[0268] - Steam generated at the heat exchanger 31: 1295 kg / h;

[0269] - Steam generated in the FT reaction unit 13: 1310 kg / h;

[0270] - Electric power generated at the first turbine 26: 5 kWe.

[0271] According to Figure 1 Example 2

[0272] Example 2 is carried out according to the present invention. Figure 1 This example illustrates the operation of a sequence having a portion 24 of the lean carbon dioxide gas effluent 18 upgraded to the air combustion unit to generate heat for the RWGS reaction unit 8. The lean carbon dioxide gas effluent 18 is obtained from the second separation unit 34 so as to enable the removal of a portion of carbon dioxide from the effluent 33 obtained from the first separation unit 15. The rich carbon dioxide gas effluent 35 is sent to the RWGS reaction unit 8. A portion 24 of the lean carbon dioxide gas effluent 18 is directed to the combustion unit.

[0273] The flue gas flow rate fed into the carbon dioxide capture unit 2 is 3641 kg / h, to which the flue gas flow rate of the combustion effluent 29 must be added, which gives a total flow rate of the feedstock 1 of 5332 kg / h. The flow of the carbon dioxide-rich effluent 3 from the carbon dioxide capture unit 2 is mixed with the carbon dioxide-rich gas effluent 35, and their total flow rate reaches 1352 kg / h and is sent to the RWGS reaction unit 8.

[0274] 1403 kg / h of water 4 is supplied to the water electrolysis unit 5, of which 708 kg / h is fresh water. The power consumption of the water electrolysis unit 5 is 6.6 MWe.

[0275] The amount of the first steam 22 generated by the FT reaction unit 13 is 1377 kg / h. Among the 2392 kg / h required for the operation of the carbon dioxide capture unit 2 and the second separation unit 34, the heat exchanger 31 generates 1332 kg / h of the second steam 23. The steam demand for the reboilers of the carbon dioxide capture unit 2 and the second separation unit 34 is covered.

[0276] When the amount of the flue gas processed is the same as in Example 1, the production rate of the hydrocarbon fraction 21 is 186 kg / h instead of 177 kg / h before.

[0277] Table 2 summarizes the flow rates at the inlets and outlets of the process units.

[0278] Table 2

[0279]

[0280] Requirements:

[0281] - Consumption of the water electrolysis unit 5: 6.6 MWe;

[0282] - Heat consumed by the RWGS reaction unit 8 at 864 °C: 0.2 MWth;

[0283] - Heat required to preheat the feedstock (3 + 35 + 7) of the RWGS unit to 864 °C: 0.8 MWth;

[0284] - Steam sent to the reboiler of the carbon dioxide capture unit 2: 2002 kg / h;

[0285] - Steam sent to the reboiler of the carbon dioxide capture unit 34: 390 kg / h.

[0286] Energy recovery:

[0287] - Heat released by the air combustion reaction unit 28 at 1200 °C (with 20% excess air): 0.56 MWth;

[0288] - Heat recovered during the cooling of the flue gas from 1200 °C to 150 °C at the outlet of the air combustion reaction unit 28: 0.7 MWth (for preheating the feedstock (3 + 35 + 7) at the inlet of unit 8);

[0289] - Steam generated at the heat exchanger 31: 1332 kg / h;

[0290] - Steam generated in the FT reaction unit 13: 1377 kg / h;

[0291] - Electrical power generated at the first turbine 26: 3.5 kWe.

Claims

1. An apparatus for capturing and converting a carbon dioxide-containing feedstock, comprising the following units: - A unit (2) for capturing carbon dioxide from the feedstock (1), adapted to produce a carbon dioxide-rich effluent (3); - A water electrolysis unit (5), suitable for converting water (4) to produce oxygen (6) and hydrogen (7); - A reverse water gas shift (RWGS) reaction unit (8), adapted to treat the carbon dioxide-rich effluent (3) with hydrogen (7) and produce an RWGS gas (9) enriched in carbon monoxide and water; - A Fischer-Tropsch reaction unit (13), adapted to convert the RWGS gas (9) and produce a FT effluent (14); - A first separation unit (15), adapted to treat at least a portion of the FT effluent (14) and produce a hydrocarbon effluent (17), a first water effluent (16) and a first gas effluent (33); - A second separation unit (34), adapted to treat the first gas effluent (33) and produce a carbon dioxide-lean gas effluent (18), and send at least part of the carbon dioxide-rich gas effluent (35) to the RWGS reaction unit (8); and - A hydrogen reaction unit (20), adapted to treat the hydrocarbon effluent (17) and produce at least one hydrocarbon fraction (21).

2. The apparatus according to claim 1, comprising an air combustion reaction unit (28), the air combustion reaction unit (28) being adapted to at least partially oxidize the carbon dioxide-lean gas effluent (18), produce a combustion effluent (29) containing carbon dioxide and water, and send the combustion effluent (29) to the carbon dioxide capture unit (2).

3. The apparatus according to claim 1 or 2, wherein the air combustion reaction unit (28) is adapted to produce heat for supplying heat energy to the RWGS reaction unit (8) and / or the carbon dioxide capture unit (2).

4. The apparatus according to claim 2 or 3, wherein the air combustion reaction unit (28) is adapted to produce heat for supplying heat energy to the RWGS reaction unit (8).

5. The apparatus according to any one of claims 2 to 4, wherein the air combustion reaction unit (28) is adapted to heat the carbon dioxide-rich effluent (3) and / or the carbon dioxide-rich gas effluent (35) and / or hydrogen (7), or integrate the reaction section of the RWGS reaction unit (8) into a combustion chamber.

6. The apparatus according to any one of the preceding claims, wherein the Fischer-Tropsch reaction unit (13) is adapted to generate a first steam (22) for supplying heat energy to the carbon dioxide capture unit (2).

7. The apparatus according to any one of the preceding claims, comprising a first heat exchanger (31), adapted to generate a second steam (23) through heat exchange between water and the RWGS gas (9).

8. The apparatus according to any one of the preceding claims, comprising a first turbine (26), used to at least partially treat the carbon dioxide-lean gas effluent (18) to generate electricity.

9. The device according to claim 8, wherein electric power is used to supply thermal energy to the RWGS reaction unit (8) and / or the carbon dioxide capture unit (2) and / or the water electrolysis unit (5).

10. The device according to any one of the preceding claims, wherein the water electrolysis unit (5) processes water from a make-up line and / or RWGS gas (9) and / or FT effluent (14).

11. The device according to any one of the preceding claims, wherein water from the RWGS gas (9) is partially or completely separated by a third separation unit (10) and sent to the water electrolysis unit (5).

12. The device according to any one of the preceding claims, comprising a carbon dioxide separation unit disposed between the RWGS reaction unit (8) and the Fischer-Tropsch reaction unit (13).

13. A method for capturing and converting carbon dioxide, comprising the following steps: - Treating a feedstock (1) in a carbon dioxide capture unit (2) to produce a carbon dioxide-rich effluent (3); - Converting water (4) in a water electrolysis unit (5) to produce oxygen (6) and hydrogen (7); - Treating the carbon dioxide-rich effluent (3) with hydrogen (7) in a reverse water gas shift (RWGS) reaction unit (8) to produce an RWGS gas (9) enriched in CO and water; - Converting the RWGS gas (9) in a Fischer-Tropsch reaction unit (13) to produce an FT effluent (14); - Treating the FT effluent (14) in a first separation unit (15) to produce at least one hydrocarbon effluent (17), a first water effluent (16), and a first gas effluent (33); - Separating the first gas effluent (33) in a second separation unit (34) to produce a carbon dioxide-rich gas effluent (35) and a carbon dioxide-lean gas effluent (18); - Sending at least part of the carbon dioxide-rich gas effluent (35) to the RWGS reaction unit (8); and - Treating the hydrocarbon effluent (17) in a hydrogen reaction unit (20) to produce at least one hydrocarbon fraction (21).

14. The method according to claim 13, wherein the RWGS reaction unit (8) comprises at least one reactor used under at least one of the following operating conditions: - A temperature between 700 °C and 1200 °C; - A pressure between 0.1 MPa and 10 MPa; - At 5000 NL / kg cata / h to 40000 NL / kg cata / h at the reactor inlet gas hourly space velocity; - A catalyst comprising at least one metal selected from the group consisting of elements Ni, Cu, Fe, Co, Pt, Pd, Ru, Ag, and Au, and / or wherein the FT reaction unit (13) comprises at least one reactor used under at least one of the following operating conditions: - A temperature between 170 °C and 280 °C; - An absolute pressure between 1.0 MPa and 6.0 MPa; - A catalyst comprising cobalt or iron.

15. The method according to any one of claims 13 and 14, wherein the air combustion reaction unit (28) comprises at least one reactor used under at least one of the following operating conditions: - An absolute pressure between 0.1 MPa and 4 MPa; - at a temperature between 600 °C and 2000 °C; - there is air for combustion having an aeration rate between 1 and 2, said aeration rate being defined as the ratio of the molar flow rate of the injected air to the theoretical air flow rate required for complete oxidation of all the fuel.

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