Combustion system, formic acid production system, and oxygen transport system

Abstract

To provide a system capable of recovering carbon dioxide discharged in a combustion process, converting the carbon dioxide into a liquid material which is low in danger and easy to transport at ordinary temperature and pressure, reducing fuel consumption and CO2 discharge accompanied by the fuel consumption by applying oxygen-enriched combustion, and improving efficiency of CO2 recovery by increasing CO2 concentration in combustion exhaust gas.SOLUTION: The combustion system includes a combustor that combusts fuel a CO2 collector that collects the CO2 supplied to a formic acid production apparatus that produces formic acid from the CO2 generated in the combustor and a O2 inputter that inputs the O2 generated in the formic acid production apparatus to the combustor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a combustion system, a formic acid production system, and an oxygen delivery system. [Background technology]

[0002] CO2 gas is contained in the exhaust gases emitted when fuel or materials are burned at power plants, factory boilers, waste incinerators, etc. CO2 gas is one of the greenhouse gases, and is thought to have the greatest impact on global warming among all the man-made greenhouse gases emitted. Therefore, as a measure against global warming, various technologies to reduce CO2 gas emissions are being vigorously developed.

[0003] To achieve carbon neutrality by 2050, it will be essential to capture and treat CO2 from emission sources such as boilers at small and medium-sized manufacturing plants and waste incineration plants. Captured CO2 needs to be buried underground or recycled. However, these processes are generally carried out in large-scale facilities for economic reasons. Therefore, CO2 captured at small and medium-sized emission sources needs to be transported to the sites where they are processed. To transport CO2 efficiently, it must be liquefied at high pressure and low temperature, for example, 2 MPa and -20°C, or transported in an even higher-pressure supercritical state. However, if CO2 could be converted into a liquid and less dangerous substance at room temperature and pressure, it would be possible to transport it safely and efficiently.

[0004] On the other hand, oxygen-enriched combustion is known as a technology that promotes energy conservation in combustion equipment by reducing fuel consumption and the resulting CO2 production, as well as improving the efficiency of waste heat recovery, and is also effective in improving the efficiency of CO2 recovery by increasing the CO2 concentration in combustion exhaust gas (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Nishimura, M., Suyari, M., Suzuki, T., Takagi, T., Journal of the Japan Institute of Energy, Vol. 79, No. 4 (2000), pp. 321-358 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional techniques require the use of oxygen produced by cryogenic separation or the production of oxygen-enriched air by membrane separation.

[0007] The objective of the present invention is to provide a system that can capture carbon dioxide emitted during the combustion process and convert it into a low-hazard, easily transportable liquid substance at room temperature and pressure, while also applying oxygen-enriched combustion to reduce fuel consumption and the associated CO2 emissions, and further increasing the CO2 concentration in the combustion exhaust gas to improve the efficiency of CO2 capture. [Means for solving the problem]

[0008] One aspect of the present invention is a combustion system having a combustion unit that combusts fuel, a CO2 capture unit that captures CO2 that is supplied to a formic acid production apparatus that produces formic acid using CO2 generated in the combustion unit as a raw material, and an O2 input unit that inputs O2 generated in the formic acid production apparatus into the combustion unit.

[0009] Another aspect of the present invention is a formic acid production system comprising: a formic acid production unit that produces formic acid using CO generated in a combustion device that combusts fuel as a raw material; a CO supply unit that supplies the CO to the formic acid production unit; and an O supply unit that supplies O generated in the formic acid production unit to the combustion device.

[0010] Yet another aspect of the present invention is an oxygen transport system including an O2 supply unit disposed between a combustion device that burns fuel and a formic acid production device that produces formic acid using CO2 generated in the combustion device as a raw material, and that supplies O2 generated in the formic acid production device to the combustion device. [Effects of the Invention]

[0011] According to one aspect of the present invention, carbon dioxide emitted during the combustion process is captured and converted into formic acid, which is a less dangerous liquid that is easily transported at room temperature and pressure. In addition, oxygen-enriched combustion reduces fuel consumption and the associated CO2 emissions, and the CO2 concentration in the combustion exhaust gas is increased, thereby improving the efficiency of CO2 capture. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an entire system including a combustion system according to an embodiment and a formic acid production system according to an embodiment. FIG. [Figure 2] 1 is a schematic diagram illustrating a combustion system according to an embodiment. [Figure 3] 1 is a schematic diagram showing a formic acid production system according to an embodiment. [Figure 4] 1 is a schematic diagram illustrating an oxygen delivery system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, common parts in the drawings will be denoted by the same reference numerals, and the description thereof will be omitted in some cases.

[0014] <Combustion system> Fig. 1 is a schematic diagram showing an entire system 100 including a combustion system, a formic acid production system, and an oxygen transport system. In Fig. 1, reference numeral 10 denotes a combustion device that burns fuel, reference numeral 20 denotes a formic acid production apparatus that produces formic acid using CO as a raw material, and reference numeral 30 denotes an O2 transport unit that transports O2 generated in the formic acid production apparatus. As shown in Fig. 1, the combustion device 10 is connected to the formic acid production apparatus 20 via the O2 transport unit 30.

[0015] In the formic acid production apparatus 20, an aqueous formic acid solution containing formic acid is produced from CO2 gas and water as shown in the following formula (1). CO2+H2O→HCOOH+1 / 2O2···(1)

[0016] Fig. 2 is a schematic diagram showing a combustion system according to an embodiment. As shown in Fig. 2, a combustion device 10 includes a combustion unit 11, a fuel supply unit 12, an O2 input unit 13, an air supply unit 14, and a CO2 capture unit 15. The combustion device 10 is an example of a combustion system according to an embodiment.

[0017] The combustion unit 11 combusts fuel. The type of the combustion unit 11 is not particularly limited, and examples thereof include steam generators, power generators, cogeneration facilities, and waste incineration facilities. The form of the combustion unit is also not particularly limited, and examples thereof include gas turbine combustors, fixed-bed combustion furnaces, moving-bed combustion furnaces, and fluidized-bed combustion furnaces.

[0018] The fuel burned in the combustion section is not particularly limited, and examples thereof include fossil fuels such as coal, kerosene, light oil, and heavy oil, liquefied petroleum gases such as propane and butane, natural gases such as city gas, bio-derived fuels such as bioethanol, biodiesel, woody biomass fuel, and biogas, and combustible waste. Note that using bio-derived fuels as fuel can realize a more carbon-neutral process.

[0019] The fuel supply unit 12 is connected to the combustion unit 11 and supplies fuel to the combustion unit 11. The form of the fuel supply unit 12 is not particularly limited, and may include, for example, a city gas pipe, a storage tank (not shown) for storing fuel, a hopper (not shown) for charging the fuel, and a transfer line (not shown) for transferring the fuel from the storage tank or hopper to the combustion unit 11. The storage tank and hopper may be provided with an adjustment valve (not shown) for adjusting the amount of fuel supplied to the combustion unit 11.

[0020] The O2 input unit 13 is connected to the combustion unit 11 and inputs O2 to the combustion unit 11. "Inputting O2" means that the combustion unit 11 receives O2. The O2 generated in the formic acid production apparatus 20 is used as the O2 input to the O2 input unit 13. Specifically, the O2 input unit 13 is connected to the formic acid production apparatus 20 and supplies the O2 produced in the formic acid production apparatus 20 to the combustion unit 11.

[0021] In the O2 input section 13, by inputting the O2 generated in the formic acid production apparatus 20 into the combustion section 11 in this manner, the O2 that is generally released outside the formic acid production apparatus 20 can be effectively utilized as a combustion-supporting gas for the combustion section 11.

[0022] An oxygen generator (not shown) may be connected to the O2 input unit 13 to supply O2 separate from the O2 generated in the formic acid production apparatus 20. In addition, in the combustion unit 11 that already uses an oxygen generator, if the oxygen generator uses a cryogenic separation method or the like, combining it with such a formic acid production apparatus 20 can reduce the amount of oxygen used from the cryogenic separation.

[0023] In the O2 input section 13, O2 generated in the formic acid production apparatus 20 may be mixed with air and supplied to the combustion section 11.

[0024] As a result, less inert gas such as nitrogen is supplied to the combustion section 11 relative to the amount of oxygen required, and the amount of heat required to heat it is reduced, allowing combustion with less fuel. Therefore, when the fuel is a fossil fuel, resources can be saved and combustion costs can be reduced. This also reduces CO2 emissions resulting from fuel combustion.

[0025] In addition, since the amount of gas ultimately discharged after heat recovery from the combustion exhaust gas is reduced, the amount of heat it carries is also reduced. This increases the efficiency of heat recovery from the combustion exhaust gas. Furthermore, the smaller amount of combustion exhaust gas allows for the size of the exhaust gas treatment equipment to be reduced.

[0026] The O2 input unit 13 may include an O2 supply amount adjustment unit. The O2 supply amount adjustment unit can adjust the amount of O2 supplied. The O2 supply amount adjustment unit may be provided with, for example, an adjustment valve (not shown) that adjusts the amount of O2 supplied to the combustion unit 11 by mixing with air.

[0027] If the O2 concentration in the air supplied to the combustion unit 11 becomes high, the combustion temperature will increase, which may result in the generation of more NOx such as NO2. Therefore, by providing such an O2 supply amount adjustment unit in the O2 input unit 13, it is possible to adjust the O2 supply amount so that the NOx concentration is below the allowable concentration.

[0028] The air supply unit 14 is connected to the combustion unit 11 and supplies air to the combustion unit 11. By providing the air supply unit 14, it is possible to supply O2 in the air supplied from the air supply unit 14, in addition to O2 from the O2 input unit 13, as the combustion oxidizing gas required by the combustion unit 11. Note that the air supply unit 14 may be connected to the O2 input unit 13 and supply air mixed with O2 from the O2 input unit 13 to the combustion unit 11.

[0029] The CO2 capture unit 15 is connected to the combustion unit 11, and separates and captures CO2 from the combustion exhaust gas and outputs it. "Outputting CO2" means that the combustion unit 11 discharges CO2 outside the combustion unit 11. The CO2 output by the CO2 capture unit 15 is the CO2 generated in the combustion unit 11. In addition, the CO2 output by the CO2 capture unit 15 is the CO2 supplied to the formic acid production apparatus.

[0030] The CO2 capture unit 15 outputs the CO2 to be supplied to a formic acid production apparatus 20 that produces formic acid using the CO2 generated in the combustion unit as a raw material, thereby making it possible to effectively utilize CO2, which is generally discharged as exhaust gas after combustion, as a raw material gas for formic acid in the formic acid production apparatus 20. The mode of the CO2 capture unit 15 is not particularly limited, and for example, an absorption method, a PSA method, a membrane separation method, etc. may be applied.

[0031] In the CO2 recovery unit 15, it is preferable to further separate the gas containing CO2 into CO2 gas and gas other than CO2, discharge the separated gas other than CO2, and supply the separated CO2 gas to the formic acid production apparatus 20.

[0032] The combustion exhaust gas generated in the combustion section 11 contains not only CO2 gas, but also gases that are inert to combustion, such as nitrogen gas, and O2 gas that was not used in combustion. Therefore, by configuring the CO2 recovery section 15 in this manner, the concentration of CO2 gas supplied to the formic acid production apparatus 20 can be increased, and gases other than CO2 gas that are not necessary for the production of formic acid can be removed in advance.

[0033] An energy recovery unit (not shown) that recovers energy such as heat and steam may be optionally provided in the combustion unit 11. The form of the energy recovery unit is not particularly limited, and may be, for example, a gas turbine, a steam turbine, a gas engine, the use of generated steam or hot water, or a combination of these.

[0034] In the combustion system of this embodiment, O2 generated in the formic acid production apparatus is input into the combustion section, thereby reducing the amount of nitrogen simultaneously supplied relative to the amount of O2 required for combustion. As a result, the CO2 concentration in the combustion exhaust gas discharged from the combustion section can be increased, thereby increasing the efficiency of CO2 separation and capture. Specifically, the separation and capture equipment can be made smaller, and the amount of energy required for separation can be reduced.

[0035] <Formic acid production system> 3 is a schematic diagram showing a formic acid production system according to an embodiment. As shown in FIG. 1, a formic acid production apparatus 20 is connected to a combustion apparatus 10.

[0036] 3, the formic acid producing apparatus 20 includes a formic acid producing unit 21, a water supply unit 22, a CO2 supply unit 23, a formic acid recovery unit 24, and an O2 supply unit 25. The formic acid producing apparatus 20 is an example of a formic acid producing system according to an embodiment.

[0037] The formic acid producing unit 21 produces formic acid using CO2 as a raw material. In the formic acid producing unit 21, formic acid is synthesized from CO2 gas and water as shown in the following formula (1). The method for measuring the content of formic acid is not particularly limited, and a general method for measuring the concentration of a solution may be used. CO2+H2O→HCOOH+1 / 2O2···(1)

[0038] As a method for producing an aqueous formic acid solution containing formic acid from CO2 gas and water, a method for producing an aqueous formic acid solution by co-electrolyzing CO2 gas is used.

[0039] There may be one or more formic acid producing units 21. For example, when there are multiple formic acid producing units 21, the formic acid producing units 21 can be configured with multiple devices.

[0040] In the formic acid producing unit 21, the CO2 used to produce formic acid is the CO2 generated and recovered in the combustion device 10. By producing formic acid using the CO2 generated in the combustion device 10 as a raw material in this way, CO2, which is generally discharged as an exhaust gas after combustion, can be effectively used as a raw material gas for formic acid in the formic acid producing unit 21.

[0041] The water supply unit 22 is connected to the formic acid production unit 21 and supplies water to the formic acid production unit 21. The form of the water supply unit 22 is not particularly limited, and includes, for example, a storage tank (not shown) for storing water, a pump (not shown) for introducing water, and a transfer line (not shown) for transferring water from the storage tank or the pump to the formic acid production unit 21.

[0042] The CO2 supply unit 23 is connected to the formic acid production unit 21 and supplies CO2 to the formic acid production unit 21. The CO2 supplied from the CO2 supply unit 23 to the formic acid production unit 21 is CO2 generated and recovered in the combustion device 10. Specifically, the CO2 supply unit 23 is connected to the CO2 capture unit 15 of the combustion device 10 and supplies CO2 output from the CO2 capture unit 15 to the formic acid production unit 21.

[0043] A transfer line (not shown) for transferring CO2 gas may be provided between the CO2 supply unit 23 and the CO2 capture unit 15 of the combustion device 10. The CO2 supply unit 23 may also be provided with an adjustment valve (not shown) for adjusting the amount of CO2 gas supplied to the formic acid production unit 21.

[0044] The formic acid recovery unit 24 is connected to the formic acid production unit 21 and recovers the formic acid aqueous solution produced in the formic acid production unit 21. The form of the formic acid recovery unit 24 is not particularly limited, and for example, it may include a storage unit (not shown) for storing formic acid. The formic acid recovery unit 24 may further include a purification unit (not shown) for purifying the formic acid aqueous solution. The formic acid recovery unit 24 may further include a concentration unit for increasing the concentration of the formic acid aqueous solution. The storage unit, purification unit, and concentration unit may be provided outside the formic acid recovery unit 24.

[0045] The O2 supply unit 25 is connected to the formic acid production unit 21 and supplies O2 generated in the formic acid production unit 21 to the combustion device 10. The O2 supplied to the combustion device 10 is O2 generated in the formic acid production unit 20. Specifically, the O2 supply unit 25 is connected to the O2 input unit 13 of the combustion device 10 via the O2 transport unit 30 and supplies O2 generated in the formic acid production unit 21 to the combustion device 10.

[0046] The O2 supply unit 25 may further be provided with an O2 purification device (not shown) that removes water vapor, mist components, and the like from the O2 gas.

[0047] The O2 inputted to the O2 input unit 13 is O2 generated in the formic acid production apparatus 20. By supplying the O2 generated in the formic acid production apparatus 20 to the combustion apparatus 10 in this manner, the O2 input unit 13 can effectively utilize the O2 that would otherwise be released to the outside of the formic acid production apparatus 20 as a combustion-supporting gas for the combustion apparatus 10.

[0048] An oxygen generator (not shown) may be connected to the combustion device 10 connected to the formic acid production device 20 to supply O2 separate from the O2 generated in the formic acid production device 20. In addition, in the combustion device 10 already using an oxygen generator, if the oxygen generator uses a cryogenic separation method or the like, combining it with such a formic acid production device 20 can reduce the amount of oxygen used from the cryogenic separation or the like.

[0049] In the formic acid production system of this embodiment, CO2 generated in the combustion device is effectively consumed as CO2 supplied to the formic acid production section as a raw material for formic acid.

[0050] <Oxygen transport system> Fig. 4 is a schematic diagram showing an oxygen transport system according to an embodiment. As shown in Fig. 4, the O2 transport unit 30 is connected to the combustion device 10 and the formic acid production device 20. The O2 transport unit 30 is provided between the combustion device 10 and the formic acid production device 20. The O2 transport unit 30 transports O2 generated in the formic acid production device to the combustion device. The O2 transport unit 30 is an example of an oxygen transport system according to an embodiment.

[0051] The O2 transport unit 30 is not particularly limited in aspect, and can be configured, for example, with a transport line for transporting O2 from the formic acid production apparatus 20 to the combustion apparatus 10 and a blower.

[0052] In the oxygen transport system of this embodiment, by having such an O2 transport unit 30, O2 generated in the formic acid production apparatus 20 can be supplied to the combustion apparatus 10.

[0053] The O2 transport section 30 may supply air mixed with O2 to the combustion device 10. The combustion device 10 requires a large amount of air as a combustion-supporting gas, but since approximately 79% of air is composed of components inactive to combustion, such as nitrogen, by mixing O2 into the air in this manner, the O2 concentration in the combustion-supporting gas can be increased.

[0054] As a result, less nitrogen gas is supplied simultaneously with the amount of oxygen required in the combustion device 10, and the amount of heat required to heat it is reduced, allowing combustion with less fuel. Therefore, when the fuel is a fossil fuel, resources can be saved and combustion costs can be reduced. This also leads to a reduction in CO2 emissions derived from the fuel.

[0055] In addition, since the amount of gas ultimately discharged after heat recovery from the combustion exhaust gas is reduced, the amount of heat it carries is also reduced. This increases the efficiency of heat recovery from the combustion exhaust gas. The smaller amount of combustion exhaust gas allows for the size of the exhaust gas treatment equipment to be reduced.

[0056] The O2 transport unit 30 may include an O2 supply amount adjusting unit that adjusts the amount of O2 supplied. The O2 supply amount adjusting unit can adjust the amount of O2 supplied. The O2 supply amount adjusting unit may be provided with, for example, an adjustment valve (not shown) that adjusts the amount of O2 supplied to the combustion device 10 by mixing with air.

[0057] If the concentration of O2 supplied to the combustion device 10 becomes high, the combustion temperature increases, which may increase the generation of NOx such as NO2. Therefore, by providing such an O2 supply amount adjustment unit in the O2 input unit 13, the amount of O2 supplied can be adjusted so that the NOx concentration is kept below the allowable concentration.

[0058] Although the embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the invention described in the claims. [Explanation of symbols]

[0059] 10 Combustion equipment 11 Combustion section 12 Fuel supply section 13 O2 input section 14 Air supply section 15 CO2 Capture Section 20 Formic acid production equipment 21 Formic Acid Production Department 22 Water supply section 23 CO2 supply section 24 Formic acid recovery section 25 O2 supply section 30 O2 transport unit

Claims

1. a combustion section that burns fuel; CO generated in the combustion section ２ The CO is supplied to a formic acid production apparatus which produces formic acid using the ２ CO2 recovery ２ A collection section; O generated in the formic acid production plant ２ is input to the combustion section. ２ an input unit; having Combustion system.

2. CO generated in a combustion device that burns fuel ２ a formic acid production department that produces formic acid using the above as a raw material; The formic acid production unit ２ CO that supplies ２ a supply unit; O2 generated in the formic acid production section ２ to the combustion device. ２ a supply unit; having Formic acid production system.

3. A combustion device that burns fuel, and CO generated in the combustion device ２ is provided between a formic acid production device which produces formic acid using the above as a raw material, O generated in the formic acid production plant ２ to the combustion device. ２ A conveying unit is provided. Oxygen delivery system.

4. The above O ２ The input unit is ２ and supplying the air mixed with the above to the combustion section. The combustion system of claim 1 .

5. The CO ２ The recovery section ２ Gas containing CO ２ Gas and CO ２ and the gas other than the CO ２ Exhausts gases other than The CO ２ 10. The combustion system of claim 1, wherein gas is supplied to the formic acid production unit.

6. The above O ２ The transport unit is ２ and supplying the air mixed with the above to the combustion device.

4. The oxygen delivery system of claim 3.

7. The above O ２ The input section is ２ Adjust the supply amount of O ２ A supply amount adjusting unit is provided. The combustion system of claim 4.

8. The above O ２ The transport section is ２ Adjust the supply amount of O ２ A supply amount adjusting unit is provided.

7. The oxygen delivery system of claim 6.

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