Carbon dioxide utilization system
Patent Information
- Application Number
- JP2022154488
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-09-28
- Publication Date
- 2025-03-21
AI Technical Summary
Existing carbon dioxide utilization systems focus on recovering carbon dioxide from combustion exhaust gases of thermal power generation equipment and gas turbines, neglecting its recovery from oil refining processes, particularly from fluid catalytic cracker exhaust gases, and do not effectively utilize oxygen as a by-product, leading to inefficiencies in energy use.
A carbon dioxide utilization system incorporating a fluid catalytic cracker, carbon dioxide electrolyzer, and optional carbon dioxide separation and recovery device, water electrolysis device, which converts carbon dioxide from fluid catalytic cracker exhaust into carbon monoxide and oxygen, utilizing oxygen for catalyst regeneration and integrating with a Fischer-Tropsch reaction device.
Enhances energy efficiency by reusing carbon dioxide from fluid catalytic cracker exhaust, reducing the need for air in catalyst regeneration, lowering energy consumption, and improving carbon monoxide yield, thereby optimizing refinery facility operations.
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Abstract
Description
[Technical field]
[0001] The technology of the present disclosure relates to a carbon dioxide utilization system. [Background technology]
[0002] In recent years, Japan's energy supply has continued to depend on fossil fuels, but it is becoming increasingly urgent to move away from this dependence on fossil fuels by switching to renewable energy while at the same time reducing carbon dioxide emissions from the use of fossil fuels.
[0003] As a technology for reducing carbon dioxide, for example, Patent Document 1 proposes a system having a fuel cell that generates electricity by moving carbonate ions derived from carbon dioxide contained in the exhaust gas from a cathode to an anode as a carbon dioxide utilization system that recovers carbon dioxide from exhaust gas generated in a facility including a combustion device. Also, Patent Document 2 proposes an apparatus for producing a synthetic gas containing carbon monoxide and hydrogen, comprising an electrolysis device that reduces carbon dioxide contained in factory exhaust gas and gas emitted from thermal power plants to produce carbon monoxide, and an electrolysis device that electrolyzes water to produce hydrogen. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] International Publication No. 2018 / 074443 Brochure [Patent Document 2] Patent Publication No. 2022-040803 Summary of the Invention [Problem to be solved by the invention]
[0005] Meanwhile, in an oil refinery, for example, in addition to the combustion exhaust gas of fossil fuels, various exhaust gases are discharged, and the amount of carbon dioxide contained in the exhaust gas cannot be ignored. A representative example of the exhaust gas containing carbon dioxide discharged from an oil refinery is the exhaust gas discharged from a catalyst regeneration tower in a fluid catalytic cracking unit. The catalyst used in the fluid catalytic cracking unit is regenerated by burning the coke (hydrocarbon) attached to its surface in the catalyst regeneration tower using air. The air used to regenerate the catalyst is discharged into the atmosphere from the top of the catalyst regeneration tower. Therefore, the exhaust gas discharged from the catalyst regeneration tower contains carbon dioxide generated by burning the coke (hydrocarbon) attached to the surface of the catalyst in addition to the carbon dioxide contained in the air, and therefore there is a need to reduce the amount of carbon dioxide emissions.
[0006] As such, in addition to reducing the amount of carbon dioxide emitted from the use of fossil fuels, capturing and reusing the carbon dioxide contained in exhaust gases that have been emitted as a matter of course in the past, and reducing the amount of said emissions, have become important issues.
[0007] The technologies for reducing carbon dioxide disclosed in the above Patent Documents 1 and 2 are aimed at recovering carbon dioxide from combustion exhaust gas discharged from thermal power generation equipment, gas turbines, etc., and focus on reusing the carbon dioxide recovered from the combustion exhaust gas. However, the subject of the study is limited to the combustion exhaust gas discharged from thermal power generation equipment, gas turbines, etc., and application to carbon dioxide contained in gas discharged from the oil refining process in oil refineries has not been considered. Furthermore, the technology disclosed in Patent Document 2 utilizes carbon monoxide obtained by reducing carbon dioxide using a carbon dioxide electrolysis device, but does not focus on the effective utilization of the by-product oxygen. Therefore, there is still room for improvement in the energy efficiency of the entire system.
[0008] The technology disclosed herein has been made in consideration of the above-mentioned circumstances, and aims to provide a carbon dioxide utilization system that reuses carbon dioxide contained in FCC flue gas that was previously exhausted and released into the atmosphere, thereby improving the energy efficiency of the entire refinery facility. [Means for solving the problem]
[0009] In order to solve the above problems, the technique of the present disclosure provides the following carbon dioxide utilization system. 1. A fluid catalytic cracking unit; A carbon dioxide electrolysis device; Equipped with a carbon dioxide supply pipe 1 for supplying an exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide electrolysis unit; The carbon dioxide electrolysis device generates at least carbon monoxide and oxygen using the carbon dioxide supplied from the carbon dioxide supply pipe 1 as a raw material. Carbon dioxide utilization system. 2.Furthermore, it is equipped with a carbon dioxide capture device, A carbon dioxide supply pipe 2 for supplying the exhaust gas discharged from the catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture unit; and a carbon dioxide supply pipe 3 for supplying the carbon dioxide captured by the carbon dioxide separation and capture device to the carbon dioxide electrolysis device; 2. The carbon dioxide utilization system according to claim 1, further comprising:
[0010] 3. A fluid catalytic cracking unit; A carbon dioxide electrolysis device; A carbon dioxide capture device; Equipped with A carbon dioxide supply pipe 2 for supplying the exhaust gas discharged from the catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture unit; and a carbon dioxide supply pipe 3 for supplying the carbon dioxide captured by the carbon dioxide separation and capture device to the carbon dioxide electrolysis device; having The carbon dioxide supplied from the carbon dioxide supply pipe 3 is used as a raw material to generate at least carbon monoxide and oxygen in the carbon dioxide electrolysis device. Carbon dioxide utilization system.
[0011] 4. The carbon dioxide utilization system according to any one of the above 1 to 3, further comprising an oxygen supply pipe 1 for supplying the oxygen generated in the carbon dioxide electrolysis device as a catalyst regeneration gas in the catalyst regeneration tower. 5. The carbon dioxide utilization system according to any one of the above 1 to 4, wherein carbon monoxide produced in the carbon dioxide electrolysis device is supplied to a Fischer-Tropsch reactor. 6.Further equipped with a water electrolysis device; 6. The carbon dioxide utilization system according to any one of 1 to 5 above, further comprising an oxygen supply pipe 2 for supplying oxygen generated in the water electrolysis apparatus as a catalyst regeneration gas to the catalyst regeneration tower. 7. The carbon dioxide utilization system according to the above item 6, wherein hydrogen produced in the water electrolysis device is supplied to a Fischer-Tropsch reactor. 8. The carbon dioxide utilization system according to claim 6 or 7, wherein carbon monoxide produced in the carbon dioxide electrolysis device and hydrogen produced in the water electrolysis device are mixed to prepare a synthesis gas. 9. The carbon dioxide utilization system according to the above item 8, wherein the synthesis gas is supplied to a Fischer-Tropsch reactor. Effect of the Invention
[0012] According to the technology disclosed herein, it is possible to provide a carbon dioxide utilization system that reuses the carbon dioxide contained in FCC flue gas that was previously exhausted and released into the atmosphere, thereby improving the energy efficiency of the entire refinery facility. [Brief description of the drawings]
[0013] [Figure 1] FIG. 2 is a flow diagram showing an example of a carbon dioxide utilization system according to the present embodiment. [Diagram 2] FIG. 2 is a flow diagram showing an example of a carbon dioxide utilization system according to the present embodiment. [Diagram 3] FIG. 2 is a flow chart showing a preferred example of the carbon dioxide utilization system of the present embodiment. [Figure 4] FIG. 2 is a schematic diagram showing a preferred example of a carbon dioxide electrolysis device used in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Hereinafter, an embodiment of the technology of the present disclosure (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values of the numerical ranges of "greater than or equal to", "less than or equal to", and "to" are values that can be arbitrarily combined, and the numerical values of the examples can also be used as the upper and lower limit values.
[0015] [Carbon dioxide utilization system] An overview of the carbon dioxide utilization system of this embodiment will be described with reference to Figures 1 and 2. Figures 1 and 2 are flow diagrams showing a preferred example of the carbon dioxide utilization system of this embodiment.
[0016] The carbon dioxide utilization system shown in FIG. 1 includes a fluid catalytic cracking unit and a carbon dioxide electrolysis unit, and has a carbon dioxide supply pipe 1 for supplying exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide electrolysis unit, and produces at least carbon monoxide and oxygen in the carbon dioxide electrolysis unit using the carbon dioxide supplied from the carbon dioxide supply pipe 1 as a raw material.
[0017] Moreover, the carbon dioxide utilization system shown in FIG. 2 includes a fluid catalytic cracking unit, a carbon dioxide electrolysis unit, and a carbon dioxide separation and capture unit, and has a carbon dioxide supply pipe 2 for supplying exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture unit, and a carbon dioxide supply pipe 3 for supplying carbon dioxide captured in the carbon dioxide separation and capture unit to the carbon dioxide electrolysis unit, and at least carbon monoxide and oxygen are produced in the carbon dioxide electrolysis unit using the carbon dioxide supplied from the carbon dioxide supply pipe 1 as a raw material.
[0018] 1 and 2 differ in whether or not they have a carbon dioxide separation and capture unit, but they have in common that they include a fluid catalytic cracking unit and a carbon dioxide electrolysis unit, and that the carbon dioxide contained in the exhaust gas discharged from the catalyst regeneration tower in the fluid catalytic cracking unit is converted into carbon monoxide and oxygen in the carbon dioxide electrolysis unit. By having such a system, the carbon dioxide contained in the exhaust gas discharged from the fluid catalytic cracking unit can be converted into carbon monoxide in the carbon dioxide electrolysis unit, and the carbon monoxide can be effectively used as a raw material in, for example, a Fischer-Tropsch reactor.
[0019] In addition, the carbon dioxide electrolysis device also produces oxygen, which can be supplied as a catalyst regeneration gas to, for example, a catalyst regeneration tower in a fluid catalytic cracking device. Air is usually used as the catalyst regeneration gas, but by using oxygen by-produced as part of the gas, the amount of air supplied as the catalyst regeneration gas can be reduced, that is, the amount of air (especially the nitrogen contained therein) supplied as the catalyst regeneration gas can be reduced, thereby reducing the amount of energy required for the sensible heat of nitrogen. In addition, the nitrogen content is relatively low, and the carbon dioxide concentration in the catalyst regeneration gas after catalyst regeneration is improved, which facilitates the reduction of carbon dioxide to carbon monoxide in the carbon dioxide electrolysis device.
[0020] In this way, the carbon dioxide utilization system of the present embodiment is a system including a fluid catalytic cracking unit and a carbon dioxide electrolysis unit, and thus not only effectively utilizes carbon dioxide as carbon monoxide, but also reduces the required amount of catalyst regeneration gas, thereby reducing the power required for supplying the catalyst regeneration gas and the energy loss caused by the nitrogen contained in the gas, thereby improving the energy efficiency of the entire refinery facility. In addition, the reduction of carbon dioxide to carbon monoxide in the carbon dioxide electrolysis unit is facilitated, and the yield of carbon monoxide is improved, thereby further improving the energy efficiency of the entire refinery facility. In this way, the system including a fluid catalytic cracking unit and a carbon dioxide electrolysis unit can synergistically improve the energy efficiency of the entire refinery facility.
[0021] Moreover, the carbon dioxide utilization system shown in Fig. 2 further includes a carbon dioxide separation and capture device compared to the system shown in Fig. 2. The carbon dioxide utilization system also includes a carbon dioxide supply pipe 2 for supplying the exhaust gas discharged from the catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture device, and a carbon dioxide supply pipe 3 for supplying the carbon dioxide captured in the carbon dioxide separation and capture device to the carbon dioxide electrolysis device.
[0022] By providing the carbon dioxide separation and capture device, it is possible to separate and capture carbon dioxide from the exhaust gas discharged from the fluid catalytic cracking unit, and therefore gas with a high carbon dioxide concentration can be supplied to the carbon dioxide electrolysis device. This facilitates the reduction of carbon dioxide to carbon monoxide in the carbon dioxide electrolysis device, and improves the yield of carbon monoxide, thereby further improving the energy efficiency of the entire refinery facility. In addition, as described above, by using oxygen generated in the carbon dioxide electrolysis device as a catalyst regeneration gas, the carbon dioxide concentration in the catalyst regeneration gas after catalyst regeneration is improved, and therefore the load of separating and capturing carbon dioxide in the carbon dioxide separation and capture device can be reduced.
[0023] Whether to use the carbon dioxide utilization system shown in Figure 1 or the carbon dioxide utilization system shown in Figure 2 may be appropriately selected depending on the carbon dioxide content contained in the exhaust gas discharged from the fluid catalytic cracking unit, etc. Furthermore, when the carbon dioxide content contained in the exhaust gas is prone to fluctuation, a system that can be used with both the systems shown in Figures 1 and 2 may be used, as shown in Figure 3. When it is possible to select either the system shown in Figure 1 or the system shown in Figure 2, it is advantageous from the standpoint of cost to adopt one of them.
[0024] The carbon dioxide utilization system shown in Figure 3 further includes a water electrolysis apparatus in addition to the systems shown in Figures 1 and 2. The system has an oxygen supply pipe 2 for supplying oxygen generated in the water electrolysis apparatus as a catalyst regeneration gas in the catalyst regeneration tower. For convenience of illustration, the system shown in Figure 3 is shown to include both the systems shown in Figures 1 and 2, but as described above, it is sufficient to include either one of them.
[0025] By providing a water electrolysis device, oxygen generated from the water electrolysis device can be supplied to the catalyst regeneration tower in the fluid catalytic cracking unit as a catalyst regeneration gas. Therefore, like oxygen generated from the carbon dioxide electrolysis device described above, the amount of catalyst regeneration gas discharged can be reduced, and energy loss caused by nitrogen contained in the catalyst regeneration gas can be reduced. In addition, the carbon dioxide concentration in the catalyst regeneration gas after catalyst regeneration is improved, which facilitates the reduction of carbon dioxide to carbon monoxide in the carbon dioxide electrolysis device, and when a carbon dioxide separation and capture device is provided, the load on the capture device can be reduced. Furthermore, by providing a water electrolysis device, hydrogen produced by the water electrolysis device can be effectively utilized as a raw material in, for example, a Fischer-Tropsch reactor, in the same manner as carbon monoxide produced by the carbon dioxide electrolysis device.
[0026] The fluid catalytic cracking unit may also be equipped with a CO boiler (not shown). The exhaust gas discharged from the top of the catalyst regeneration tower may contain carbon monoxide. In this case, by providing a CO boiler, the carbon monoxide contained in the exhaust gas discharged from the top of the catalyst regeneration tower can be combusted to recover heat. When a CO boiler is provided, the flue gas discharged from the top of the catalyst regeneration tower is supplied to the carbon dioxide electrolysis device via the CO boiler. In the carbon dioxide utilization system of this embodiment, the carbon dioxide supply piping 1 is a piping from the catalyst regeneration tower to the carbon dioxide electrolysis device when a CO boiler is not provided, and is a piping from the CO boiler to the carbon dioxide electrolysis device when a CO boiler is provided.
[0027] Each device constituting the carbon dioxide utilization system of this embodiment will be described.
[0028] (Fluid catalytic cracking equipment) The recovery system of this embodiment includes a fluid catalytic cracking unit. The fluid catalytic cracking unit is a unit that cracks heavy oil fractions, such as desulfurized heavy oil fractions hydrodesulfurized in a heavy oil direct desulfurization unit or a heavy oil indirect desulfurization unit, using a fluid catalytic cracking catalyst to convert them into useful fractions, such as cracked gasoline fractions. In the recovery system of this embodiment, the fluid catalytic cracking unit can be any unit having a configuration that is normally used as a fluid catalytic cracking unit in an oil refinery, without any particular limitation.
[0029] A fluid catalytic cracking unit is broadly comprised of a reaction tower in which a heavy oil fraction is brought into contact with a fluid catalytic cracking catalyst to convert the heavy oil fraction into useful fractions such as cracked gasoline fraction, and a catalyst regeneration tower in which the coke (hydrocarbons) that adheres to the surface of the fluid catalytic cracking catalyst used in the reaction tower is burned and removed using a catalyst regeneration gas (usually air), thereby regenerating the fluid catalytic cracking catalyst. In addition, the reaction tower and the catalyst regeneration tower are connected by a spent catalyst transfer line for transferring the used catalyst used in the reaction tower to the catalyst regeneration tower, and a regenerated catalyst transfer line for supplying the catalyst regenerated in the catalyst regeneration tower to the reaction tower, thereby circulating the catalyst.
[0030] In a catalyst regeneration tower, air, which is normally used as a catalyst regeneration gas, is supplied to the catalyst regeneration tower by an air blower and used to regenerate the catalyst by burning the coke (hydrocarbon) that adheres to the surface of the used catalyst in the catalyst regeneration tower. The air is then discharged as exhaust gas from the top of the catalyst regeneration tower, accompanied by carbon dioxide produced by the combustion of the coke (hydrocarbon).
[0031] As described above, in the carbon dioxide utilization system of this embodiment, the fluid catalytic cracking unit may be equipped with a CO boiler, and in this case, the exhaust gas discharged from the top of the catalyst regeneration tower after combustion in the CO boiler (after passing through the CO boiler) is supplied to the carbon dioxide electrolysis device. Therefore, in the carbon dioxide utilization system of this embodiment, the exhaust gas discharged from the top of the catalyst regeneration tower that is supplied to the carbon dioxide electrolysis device may be the exhaust gas discharged from the top of the catalyst regeneration tower as it is, or may be the exhaust gas after combustion of the exhaust gas in the CO boiler (after passing through the CO boiler).
[0032] Oxygen generated in the carbon dioxide electrolysis device is preferably supplied as catalyst regeneration gas via oxygen supply piping 1. Oxygen may be supplied either upstream or downstream of the air blower, i.e., the oxygen supply piping 1 may be connected either upstream or downstream of the air blower in the catalyst regeneration gas piping, and may be appropriately determined taking into consideration the pressure balance and the like. Connecting the oxygen supply piping downstream of the air blower allows the power of the air blower to be reduced, which is preferable in terms of improving energy efficiency. In addition, oxygen generated in a water electrolysis device described later is supplied as a catalyst regeneration gas via oxygen supply pipe 2 and may be supplied either upstream or downstream of the air blower, similar to the oxygen generated in the carbon dioxide electrolysis device described above.
[0033] (Carbon dioxide electrolysis device) The recovery system of this embodiment includes a carbon dioxide electrolysis device. The carbon dioxide electrolysis device is a device that electrolyzes and reduces carbon dioxide contained in the exhaust gas discharged from the catalyst regeneration tower of the fluid catalytic cracking device to generate carbon monoxide, oxygen, etc. The exhaust gas discharged from the catalyst regeneration tower in the fluid catalytic cracking device is supplied to the carbon dioxide electrolysis device via carbon dioxide supply piping 1 for supplying the exhaust gas to the carbon dioxide electrolysis device.
[0034] In the recovery system of the present embodiment, the carbon dioxide electrolysis device can be any device having a configuration that is usually adopted as a carbon dioxide electrolysis device, without any particular limitation. In addition, when a carbon dioxide electrolysis device is provided in an oil refinery facility, the existing carbon dioxide electrolysis device can also be used.
[0035] As the carbon dioxide electrolysis device, for example, a device including a cathode having a carbon dioxide reduction catalyst layer, an anode constituting a pair of electrodes together with the cathode, an electrolyte layer present in contact between the cathode and the anode, and a voltage application unit that applies a voltage between the cathode and the anode may be used.
[0036] A preferred embodiment of the carbon dioxide electrolysis device in the recovery system of this embodiment will be described with reference to Fig. 4. The carbon dioxide electrolysis device shown in Fig. 4 includes a cathode (negative electrode) 200 constituting an electrode, an anode (positive electrode) 400 constituting a pair of electrodes with the cathode 200, an electrolyte layer 300 that is in contact with the cathode 200 and the anode 400, and a voltage application unit 700 that applies a voltage between the cathode 200 and the anode 400. The cathode 200 has a gas diffusion layer 210 and a catalyst layer 220 that includes a catalyst 221, a cathode current collector (cathode current collector) 100 and an anode current collector (anode current collector) 500 that apply a voltage between the cathode 200 and the anode 400 by the voltage application unit, and is also shown to have an electrolyte 600.
[0037] The production of carbon monoxide by reduction of carbon dioxide takes place at the cathode. The reduction reaction of carbon dioxide at the cathode differs depending on the type of electrolyte layer. When a cation exchange resin is used in the electrolyte layer, the reduction reaction takes place according to the following reaction formula (1), and when an anion exchange resin is used in the electrolyte layer, the reduction reaction takes place according to the following reaction formula (2).
[0038] CO2+2H + +2e - →CO+H2O (1) H2O+CO2+2e - →CO+2OH - (2)
[0039] Furthermore, an oxidation reaction occurs at the anode (positive electrode), producing oxygen. The oxidation reaction at the anode also differs depending on the type of electrolyte layer. When a cation exchange resin is used in the electrolyte layer, the oxidation reaction occurs according to the following reaction formula (3), and when an anion exchange resin is used in the electrolyte layer, the oxidation reaction occurs according to the following reaction formula (4). In this way, oxygen is produced at the anode (positive electrode).
[0040] 2H2O→O2+4H + +4e - (3) 4OH - →O2+2H2O+4e - (4)
[0041] In the carbon dioxide electrolysis device used in the recovery system of this embodiment, the materials and configurations forming the cathode, anode, electrolyte layer, etc. are not particularly limited, and may be appropriately selected from known devices. The configuration of the voltage application unit is also not particularly limited, and may be appropriately selected from known devices. Below, a preferred example of the materials forming the cathode, anode, electrolyte layer, etc. will be described, but it goes without saying that the present invention is not limited to this.
[0042] The cathode in the carbon dioxide electrolysis device has, for example, a catalyst layer containing a catalyst that promotes the reduction reaction of carbon dioxide and a gas diffusion layer. The catalyst in the catalyst layer is not particularly limited as long as it is a catalyst that promotes the reduction reaction of carbon dioxide, and representative preferred examples include catalysts using at least one type of inorganic fine particles selected from gold, silver, copper, nickel, iron, cobalt, zinc, chromium, palladium, tin, manganese, aluminum, indium, bismuth, molybdenum, carbon nitride, etc.; at least one type of metal selected from copper, nickel, iron, cobalt, zinc, manganese, molybdenum, and aluminum, or a metal complex in which a ligand is coordinated to the ion of the metal; and the like, and using a conductive carbon material that can be used as a gas diffusion layer, such as carbon black (furnace black, acetylene black, ketjen black, etc.), activated carbon, graphite, carbon nanotubes, carbon nanofibers, nanoporous carbon, etc., as a catalyst species. The catalyst layer is preferably a layer containing these catalysts and further containing an ionomer, which is a conductive polymer electrolyte such as a cation exchange resin or an anion exchange resin, as a binder resin.
[0043] The gas diffusion layer may be made of carbon paper, nonwoven fabric, or metal mesh, for example, graphite carbon, glassy carbon, titanium, SUS steel, or the like.
[0044] As the anode (positive electrode), a gas diffusion electrode including a gas diffusion layer made of an electrode material such as Ir, IrO2, Ru, RuO2, Co, CoOx, Cu, CuOx, Fe, FeOx, FeOOH, FeMn, Ni, NiOx, NiOOH, NiCo, NiCe, NiC, NiFe, NiCeCoCe, NiLa, NiMoFe, NiSn, NiZn, SUS, Au, or Pt is preferably used.
[0045] As the electrolyte layer, for example, a polymer membrane having an ionomer as a solid electrolyte, which is a conductive polymer electrolyte such as a cation exchange resin or an anion exchange resin described as the binder resin that can be used in the catalyst layer, is preferably used.
[0046] As the electrolyte, for example, an aqueous solution having a pH of 5 or more, such as an aqueous carbonate solution, an aqueous hydrogen carbonate solution, an aqueous sulfate solution, an aqueous borate solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or an aqueous sodium chloride solution, is preferably used.
[0047] Examples of metal materials constituting the cathode current collector (negative electrode current collector) include copper, nickel, stainless steel, nickel-plated steel, brass, etc., and examples of shapes include metal foil, metal plate, metal thin film, expanded metal, punched metal, foamed metal, etc. Examples of metal materials constituting the anode current collector include titanium, copper, nickel, stainless steel, nickel-plated steel, and brass.
[0048] Thus, in a carbon dioxide electrolysis device, the reaction that proceeds may vary depending on the material used in the electrolyte layer, but carbon monoxide is mainly produced at the cathode (negative electrode) and oxygen is produced at the anode (positive electrode). The carbon monoxide produced in the carbon dioxide electrolysis device can be effectively utilized by, for example, supplying it to a Fischer-Tropsch reactor. The use of carbon monoxide is not limited to being a raw material for a Fischer-Tropsch reactor, and it can also be effectively utilized for other purposes, such as fuel gas for gas turbines. In addition, the oxygen generated in the carbon dioxide electrolysis device can be used, for example, as oxygen for oxygen enrichment in iron making and non-ferrous metal refining, an oxidizing agent for oxidation reactions in the chemical field, etc. In the system of this embodiment, it is preferable to provide an oxygen supply pipe 1 and use the oxygen as a catalyst regeneration gas for a fluid catalytic cracking device.
[0049] (Carbon dioxide capture equipment) The capture system of this embodiment shown in Fig. 2 includes a carbon dioxide capture device. The carbon dioxide capture device is a device that separates and captures carbon dioxide contained in gas, and is usually installed in an oil refinery facility, so an existing carbon dioxide capture device may be used, or a carbon dioxide capture device newly installed for the capture system of this embodiment may be used.
[0050] In the recovery system of this embodiment, there are no particular limitations on the type of carbon dioxide separation and recovery apparatus, and various separation and recovery methods can be employed, such as a chemical absorption method using a compound that chemically absorbs carbon dioxide, such as an active amine such as monoethanolamine or hindered amine, ammonia water, or an aqueous potassium carbonate solution; a physical absorption method in which carbon dioxide is absorbed under high pressure in a physical absorption liquid that can absorb carbon dioxide, such as N-methylpyrrolidone, a dimethyl ether solution of polyethylene glycol, or polypropylene carbonate, and separated; a membrane separation method in which separation is performed using a permeable membrane that selectively allows carbon dioxide to pass through; and a cryogenic separation method in which carbon dioxide is liquefied at extremely low temperatures and separated using the difference in boiling points.
[0051] In oil refinery facilities, carbon dioxide separation and capture equipment using the above-mentioned chemical absorption method and physical absorption method is often installed, and these methods are highly reliable. Therefore, in consideration of the reliability of the capture system of this embodiment, a carbon dioxide separation and capture equipment using a general-purpose method such as the chemical absorption method or the physical absorption method may be used. If an existing carbon dioxide separation and capture equipment in an oil refinery facility can be used, it may be used in the capture system of this embodiment as described above, and if a new carbon dioxide separation and capture equipment is installed for this capture system, it is preferable to use a carbon dioxide separation and capture equipment using these general-purpose methods.
[0052] The capture system of this embodiment shown in Fig. 1 may further include a carbon dioxide separation and capture unit (see Fig. 3). In this case, the entire amount of the flue gas discharged from the fluid catalytic cracking unit may be supplied to the carbon dioxide separation and capture unit, and the carbon dioxide generated in the carbon dioxide separation and capture unit may be supplied to the carbon dioxide electrolysis unit, or a portion of the carbon dioxide may be directly supplied to the carbon dioxide electrolysis unit, and the remainder may be supplied to the carbon dioxide separation and capture unit. The exhaust gas can be distributed and adjusted to the carbon dioxide supply pipe 1 and the carbon dioxide supply pipe 2, taking into consideration the concentration of carbon dioxide in the exhaust gas discharged from the fluid catalytic cracking unit, the amount of exhaust gas, etc., and, if an existing unit is used as the carbon dioxide separation and capture unit, the operating load of the existing unit, etc.
[0053] (Water electrolysis device) The recovery system of the present embodiment may include a water electrolysis device. The water electrolysis device is a device that generates oxygen and hydrogen by electrolyzing water.
[0054] In the recovery system of the present embodiment, the water electrolysis device may be any device having a configuration that is normally used as a water electrolysis device, without any particular limitations. In addition, in cases where a water electrolysis device is provided within the refinery facility, the existing water electrolysis device may be used.
[0055] The water electrolysis device may include, for example, a cathode, an anode constituting a pair of electrodes together with the cathode, an electrolyte layer in contact with the cathode and the anode, and a voltage application unit that applies a voltage between the cathode and the anode. That is, the configuration of the water electrolysis device having the cathode, electrolyte layer, anode, and voltage application unit that applies a voltage between the cathode and the anode is the same as that of the carbon dioxide electrolysis device described above.
[0056] The type of water electrolysis device can be appropriately selected from alkaline water electrolysis, solid polymer water electrolysis, high temperature steam electrolysis (solid oxide steam electrolysis), and the like.
[0057] For example, the cathode (negative electrode) may be a gas diffusion electrode including a gas diffusion layer, such as a porous conductive electrode such as Ni-YSZ (a mixture of nickel and yttria-stabilized zirconia) or Ni-CeSmO (a mixture of nickel and CeO2 with added Sm), and the anode (positive electrode) may be a porous conductive electrode made of a La-Sr-Mn (LSM) composite oxide or the like. Preferred examples of the electrolyte include solid oxide electrolytes having oxide ion conductivity, such as zirconium oxide doped with yttrium, calcium, scandium, or the like (YSZ (yttria-stabilized zirconia), CSZ, ScSZ), which conducts oxide ions, and yttrium-doped barium zirconate having hydrogen ion conductivity.
[0058] In a water electrolysis device, the reaction at the cathode (negative electrode) varies depending on the type of electrolyte layer. When an electrolyte having hydrogen ion conductivity is used in the electrolyte layer, the reduction reaction occurs according to the following reaction formula (5). When an electrolyte having oxide ion conductivity is used in the electrolyte layer, the reduction reaction occurs according to the following reaction formula (6).
[0059] 4H + +4e - →2H2(5) 2H2O+4e - →2H2+2O 2- (6)
[0060] In a water electrolysis device, the reaction at the anode (positive electrode) varies depending on the type of electrolyte layer. When an electrolyte having hydrogen ion conductivity is used in the electrolyte layer, the oxidation reaction occurs according to the following reaction formula (7). When an electrolyte having oxide ion conductivity is used in the electrolyte layer, the oxidation reaction occurs according to the following reaction formula (8).
[0061] 2H2O→O2+4H + +4e - (7) 2O 2- →O2+4e - (8)
[0062] Thus, in the water electrolysis device, hydrogen is produced at the cathode (negative electrode) and oxygen is produced at the anode (positive electrode), although the reactions that proceed may vary depending on the material used in the electrolyte layer. The oxygen produced in the water electrolysis device can be used in various applications, similar to the oxygen produced in the carbon dioxide electrolysis device described above. In the system of this embodiment, it is preferable to provide an oxygen supply pipe 2 and use the oxygen as a catalyst regeneration gas for the fluid catalytic cracking device. The hydrogen produced in the electrolysis device can be effectively used by supplying it to, for example, a Fischer-Tropsch reactor. The applications of hydrogen are not limited to the raw material for the Fischer-Tropsch reactor, and it can also be effectively used for other applications, such as fuel gas for gas turbines.
[0063] When the carbon dioxide utilization system of the present embodiment is equipped with a water electrolysis device, both the carbon monoxide produced in the carbon dioxide electrolysis device and the hydrogen produced in the water electrolysis device can be effectively utilized as raw materials for a Fischer-Tropsch reactor or for other applications. The carbon monoxide produced in the carbon dioxide electrolysis device and the hydrogen produced in the water electrolysis device can be mixed to prepare a synthesis gas, or the carbon monoxide and the hydrogen can be supplied to desired applications, respectively. Also, carbon monoxide produced in the carbon dioxide electrolysis device and hydrogen produced in the water electrolysis device can be mixed to form a synthesis gas, which can be supplied to the Fischer-Tropsch reactor as a feed gas. EXAMPLES
[0064] Next, the technology of the present disclosure will be specifically explained using examples, but the technology of the present disclosure is not limited to these examples in any way.
[0065] (Example) In the catalyst regeneration tower of the fluid catalytic cracking unit, the supply amount of air used for catalyst regeneration was 31.2 parts by mass / day (24 parts by mass / day as nitrogen gas), and the flow rate of the exhaust gas discharged from the catalyst regeneration tower was 10 parts by mass / day (as carbon dioxide), and the exhaust gas was supplied to the carbon dioxide electrolysis device. The oxygen gas generated from the carbon dioxide electrolysis device was 3.6 parts by mass / day, and when the 3.6 parts by mass / day of oxygen gas generated was used as part of the catalyst regeneration gas for the fluid catalytic cracking unit, the supply amount of air for catalyst regeneration, which was supplied from 31.2 parts by mass / day, was reduced by 50% to 15.6 parts by mass / day (12 parts by mass / day as nitrogen gas). As a result of the above, not only can carbon dioxide be effectively utilized, but the energy required for the sensible heat of nitrogen can also be halved. Furthermore, the power required for the air blower for catalyst regeneration can also be halved. Therefore, it has been confirmed that the carbon dioxide contained in FCC exhaust gas that was previously exhausted and released into the atmosphere can be reused, thereby improving the energy efficiency of the entire refinery facility. [Industrial Applicability]
[0066] The carbon dioxide utilization system of the present embodiment reuses carbon dioxide contained in FCC flue gas that was previously exhausted and released into the atmosphere, improving the energy efficiency of the entire refinery facility. Therefore, it is suitable for use as an extension to an existing refinery facility.
Claims
1. a fluid catalytic cracking unit; A carbon dioxide electrolysis device; Equipped with a carbon dioxide supply pipe 1 for supplying an exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide electrolysis unit; The carbon dioxide electrolysis device generates at least carbon monoxide and oxygen using the carbon dioxide supplied from the carbon dioxide supply pipe 1 as a raw material. Carbon dioxide utilization system.
2. It also has a carbon dioxide capture and storage unit. A carbon dioxide supply pipe 2 for supplying exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture unit; and A carbon dioxide supply pipe 3 for supplying the carbon dioxide captured by the carbon dioxide separation and capture device to the carbon dioxide electrolysis device; The carbon dioxide utilization system according to claim 1 .
3. a fluid catalytic cracking unit; A carbon dioxide electrolysis device; A carbon dioxide capture device; Equipped with A carbon dioxide supply pipe 2 for supplying exhaust gas discharged from a catalyst regeneration tower in the fluid catalytic cracking unit to the carbon dioxide separation and capture unit; and A carbon dioxide supply pipe 3 for supplying the carbon dioxide captured by the carbon dioxide separation and capture device to the carbon dioxide electrolysis device; having generating at least carbon monoxide and oxygen in the carbon dioxide electrolysis device using the carbon dioxide supplied from the carbon dioxide supply pipe 3 as a raw material; Carbon dioxide utilization system.
4. 4. The carbon dioxide utilization system according to claim 1, further comprising an oxygen supply pipe for supplying oxygen generated in the carbon dioxide electrolysis device as a catalyst regeneration gas in the catalyst regeneration tower.
5. 4. The carbon dioxide utilization system according to claim 1, wherein carbon monoxide produced in the carbon dioxide electrolysis device is supplied to a Fischer-Tropsch reaction device.
6. It also has a water electrolysis device.
4. The carbon dioxide utilization system according to claim 1, further comprising an oxygen supply pipe for supplying oxygen generated in the water electrolysis device as a catalyst regeneration gas in the catalyst regeneration tower.
7. 7. The system for utilizing carbon dioxide according to claim 6, wherein hydrogen produced in the water electrolysis device is supplied to a Fischer-Tropsch reactor.
8. 7. The carbon dioxide utilization system according to claim 6, wherein carbon monoxide produced in the carbon dioxide electrolysis device and hydrogen produced in the water electrolysis device are mixed to prepare a synthesis gas.
9. The carbon dioxide utilization system according to claim 8, wherein the synthesis gas is supplied to a Fischer-Tropsch reactor.