Ammonia reforming combustion system

Abstract

To provide an ammonia reforming combustion system that can stabilize combustion in a combustor even in situations where undecomposed ammonia gas is introduced into the combustor due to, for example, changes in operating conditions at the operation start stage or during operation.SOLUTION: The system comprises: a reformer 32 that reforms ammonia gas using heat of high-temperature gas generated by combustion of a mixed gas of ammonia gas supplied by an ammonia gas supply device 31 and reforming air supplied by a reforming air supply device 34 to generate reformed gas containing hydrogen; a combustor 33 that combusts a mixed gas of the reformed gas generated by the reformer 32 and combustion air supplied by a combustion air supply device 35; and a combustion promoting gas supply device 100 that supplies combustible gas and / or oxidant gas to the combustor 33.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ammonia reforming combustion system including an ammonia gas supplying device that supplies ammonia gas, a reforming air supplying device that supplies reforming air, and a combustion air supplying device that supplies combustion air. [Background technology]

[0002] For example, in waste incineration furnaces, fossil fuels such as city gas and kerosene are used as fuels for starting up the furnace. In recent years, there has been a demand to switch from fossil fuels to carbon-free fuels in order to achieve decarbonization. Hydrogen and ammonia have attracted attention as carbon-free fuels, and efforts to popularize them are accelerating.

[0003] While hydrogen is considered difficult to store, ammonia can be stored relatively easily, and so its introduction is expected. However, since ammonia has poor combustibility, technology is being developed to reform ammonia and burn it (see, for example, Patent Document 1).

[0004] In the combustion device described in Patent Document 1, a catalyst containing section containing a catalyst that decomposes ammonia gas into hydrogen gas and nitrogen gas is provided inside a reformer into which ammonia gas is introduced, and a heater is provided as heating means for activating the decomposition action of the catalyst of the ammonia gas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-15464 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the combustion device described in Patent Document 1, at the start of operation, the heater does not heat the catalyst sufficiently, and the catalyst does not decompose ammonia gas sufficiently, so that undecomposed ammonia gas passes through the catalyst housing without being decomposed by the catalyst and is introduced into the combustion tube (combustor), causing poor combustion in the combustion tube. Even during operation, the decomposition of ammonia gas may be delayed due to changes in operating conditions, etc., and undecomposed ammonia gas may be introduced into the combustion tube, causing unstable combustion in the combustion tube.

[0007] The present invention has been made in consideration of the above problems, and has an object to provide an ammonia reforming combustion system that can stabilize combustion in a combustor even in a situation where undecomposed ammonia gas is introduced into the combustor due to, for example, the start-up stage of operation or changes in operating conditions during operation. [Means for solving the problem]

[0008] The characteristic configuration of the ammonia reforming combustion system according to the present invention for solving the above problems is as follows: An ammonia reforming combustion system comprising an ammonia gas supplying device that supplies ammonia gas, a reforming air supplying device that supplies reforming air, and a combustion air supplying device that supplies combustion air, a reformer that uses heat of high-temperature gas generated by combustion of a mixed gas of ammonia gas supplied by the ammonia gas supply device and reforming air supplied by the reforming air supply device to reform the ammonia gas and generate a reformed gas containing hydrogen; a combustor that burns a mixed gas of the reformed gas generated by the reformer and the combustion air supplied by the combustion air supply device; a combustion promoting gas supply device for supplying a combustible gas and / or an oxidizing gas to the combustor; The purpose of this project is to provide the following:

[0009] According to the ammonia reforming combustion system of this configuration, for example, in a situation where ammonia gas is not completely decomposed in the reformer due to a change in operating conditions during operation or the like, and undecomposed ammonia gas is introduced from the reformer to the combustor, a combustible gas and / or an oxidizer gas are supplied to the combustor. When the combustible gas is supplied to the combustor, the combustible gas is burned and the ammonia gas is ignited from the burned combustible gas, so that the combustion in the combustor is stabilized. In addition, when the oxidizer gas is supplied to the combustor, the amount of combustion supporting gas in the combustor is relatively increased, so that the combustion in the combustor is stabilized. Furthermore, when both the oxidizer gas and the combustible gas are supplied to the combustor, the combustion in the combustor is more stabilized due to a synergistic effect. Therefore, even in a situation where undecomposed ammonia gas is introduced into the combustor due to a change in operating conditions during operation or the like, the combustion in the combustor can be stabilized.

[0010] In the ammonia reforming combustion system according to the present invention, It is preferable to provide a combustion promoting gas supply amount control means for controlling the supply amount of the combustible gas and / or the oxidizer gas based on at least one of the combustion temperature of the combustor, the gas temperature of the reformed gas, and the concentration of oxygen contained in the reformed gas.

[0011] According to the ammonia reforming combustion system of this configuration, the supply amount of combustible gas and / or oxidizer gas is controlled based on at least one of the combustion temperature of the combustor, the gas temperature of the reformed gas, and the concentration of oxygen contained in the reformed gas. Therefore, the combustible gas and / or oxidizer gas is supplied to the combustor without excess or deficiency, and the combustion in the combustor can be efficiently stabilized.

[0012] In the ammonia reforming combustion system according to the present invention, The combustible gas and / or the oxidant gas is preferably hydrogen gas and / or oxygen gas produced by electrolyzing water using electricity generated by utilizing heat obtained by heat exchange with exhaust gas in a combustion facility.

[0013] According to the ammonia reforming combustion system of this configuration, it is not necessary to separately procure combustible gas and / or oxidant gas from outside the combustion facility, and the procurement cost of combustible gas and / or oxidant gas can be reduced. In addition, by effectively utilizing the exhaust heat of the combustion facility, not only can carbon dioxide be directly reduced, but also carbon dioxide generated secondarily during transportation of fuel can be reduced because the process can be completed within the combustion facility, which contributes to decarbonization.

[0014] Next, the characteristic configuration of the ammonia reforming combustion system according to the present invention for solving the above problems is as follows: An ammonia reforming combustion system comprising an ammonia gas supplying device that supplies ammonia gas, a reforming air supplying device that supplies reforming air, and a combustion air supplying device that supplies combustion air, a reformer that uses heat of high-temperature gas generated by combustion of a mixed gas of ammonia gas supplied by the ammonia gas supply device and reforming air supplied by the reforming air supply device to reform the ammonia gas and generate a reformed gas containing hydrogen; a combustor that burns a mixed gas of the reformed gas generated by the reformer and the combustion air supplied by the combustion air supply device; A pilot burner attached to the combustor; A combustible gas supply device that supplies combustible gas to the pilot burner; The purpose of this study is to provide

[0015] According to the ammonia reforming combustion system of this configuration, for example, in a situation where ammonia gas is not completely decomposed in the reformer due to the start-up stage or changes in operating conditions during operation, and undecomposed ammonia gas is introduced from the reformer to the combustor, combustible gas is supplied to a pilot burner attached to the combustor. When the combustible gas is supplied to the pilot burner, the combustible gas ejected from the pilot burner into the combustor is burned to form a flame, and the flame is transferred from the pilot burner flame to the ammonia gas, so that the combustion in the combustor is stabilized. Therefore, even in a situation where undecomposed ammonia gas is introduced into the combustor due to the start-up stage or changes in operating conditions during operation, the combustion in the combustor can be stabilized.

[0016] In the ammonia reforming combustion system according to the present invention, It is preferable to further comprise a combustible gas supply amount control means for controlling the supply amount of the combustible gas based on the combustion temperature of the combustor.

[0017] According to the ammonia reforming combustion system of this configuration, the supply amount of combustible gas is controlled based on the combustion temperature of the combustor, so that the combustible gas is supplied to the pilot burner without excess or deficiency, and the combustion in the combustor can be efficiently stabilized.

[0018] In the ammonia reforming combustion system according to the present invention, It is preferable to include an oxidant gas supply device for supplying an oxidant gas to the combustor.

[0019] According to the ammonia reforming combustion system of this configuration, the amount of combustion supporting gas in the combustor is relatively increased by supplying the oxidant gas to the combustor, so that the combustion in the combustor can be further stabilized.

[0020] In the ammonia reforming combustion system according to the present invention, It is preferable to further comprise an oxidant gas supply amount control means for controlling the supply amount of the oxidant gas based on the combustion temperature of the combustor.

[0021] According to the ammonia reforming combustion system of this configuration, the supply amount of oxidant gas is controlled based on the combustion temperature of the combustor, so that the oxidant gas is supplied to the combustor without excess or deficiency, and combustion in the combustor can be efficiently stabilized.

[0022] In the ammonia reforming combustion system according to the present invention, The flammable gas is preferably hydrogen gas produced by electrolyzing water using electricity generated by utilizing heat obtained by heat exchange with exhaust gas in a combustion facility.

[0023] According to the ammonia reforming combustion system of this configuration, it is not necessary to separately procure combustible gas from outside the combustion facility, and the procurement cost of combustible gas can be reduced. In addition, by effectively utilizing the exhaust heat of the combustion facility, not only can carbon dioxide be directly reduced, but also carbon dioxide generated secondarily during the transportation of fuel can be reduced because the treatment can be completed within the combustion facility, which contributes to decarbonization.

[0024] In the ammonia reforming combustion system according to the present invention, The oxidant gas is preferably oxygen gas produced by electrolyzing water using electricity generated by utilizing heat obtained by heat exchange with exhaust gas in a combustion facility.

[0025] According to the ammonia reforming combustion system of this configuration, it is not necessary to separately procure oxidant gas from outside the combustion facility, and the procurement cost of oxidant gas can be reduced. In addition, by effectively utilizing the exhaust heat of the combustion facility, not only can carbon dioxide be directly reduced, but also carbon dioxide generated secondarily during the transportation of fuel can be reduced because the process can be completed within the combustion facility, which contributes to decarbonization. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a combustion facility to which the ammonia reforming combustion system of the present invention is applied. [Diagram 2]FIG. 2 is a block diagram showing a schematic configuration of an ammonia reforming combustion system according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a flow chart showing the procedure for operating the ammonia reforming combustion system. [Figure 4] FIG. 4 is a flowchart showing the procedure of the combustion promotion gas supply amount control process. [Diagram 5] FIG. 5 is a flowchart showing the procedure of the reforming air supply amount control process. [Figure 6] FIG. 6 is a flowchart showing the procedure of the combustion air supply amount control process. [Figure 7] FIG. 7 is a block diagram showing a schematic configuration of an ammonia reforming combustion system according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings.

[0028] <Outline of combustion facility> Fig. 1 is a block diagram showing a schematic configuration of a combustion facility 1 to which an ammonia reforming combustion system 30 of the present invention is applied. The combustion facility 1 shown in Fig. 1 mainly includes a combustion furnace 2, an exhaust gas treatment facility 3, a power generation facility 4, a water electrolysis device 5, a hydrogen storage and supply device 6, an oxygen storage and supply device 7, a fermentation device 8, a biogas storage and supply device 9, a carbon dioxide recovery device 10, a reduction device 11, a methane storage and supply device 12, and an ammonia reforming combustion system 30. The ammonia reforming combustion system 30 collectively refers to an ammonia reforming combustion system 30A of a first embodiment and an ammonia reforming combustion system 30B of a second embodiment, which will be described later.

[0029] <Combustion furnace> The combustion furnace 2 burns materials to be combusted, such as waste materials such as municipal waste, biomass fuel, etc. The type of the combustion furnace 2 is not limited as long as it can burn materials to be combusted, and examples of the furnace include a stoker type combustion furnace and a fluidized bed type combustion furnace.

[0030] <Exhaust gas treatment equipment> The exhaust gas treatment equipment 3 treats exhaust gas generated by combustion in the combustion furnace 2. The exhaust gas treatment equipment 3 includes a boiler 13, a temperature reducing tower 14, a dust collector 15, a denitration device 16, an induced draft fan 17, and a chimney 18, which are arranged in this order from the upstream side to the downstream side of the exhaust gas flow path. In the exhaust gas treatment equipment 3, the exhaust gas from the combustion furnace 2 is sent in this order to the boiler 13, the temperature reducing tower 14, the dust collector 15, and the denitration device 16 by the induction action of the induced draft fan 17. The exhaust gas is subjected to heat exchange in the boiler 13, cooled to a predetermined temperature in the temperature reducing tower 14, and then sent to the dust collector 15. The exhaust gas from which dust has been removed in the dust collector 15 is sent to the denitration device 16. The exhaust gas denitrified in the denitration device 16 is discharged to the outside of the system via the chimney 18 by the induced draft fan 17.

[0031] Here, the boiler 13 is equipped with a heat exchange section (not shown) that exchanges heat with the exhaust gas discharged from the combustion furnace 2, and is configured to generate water vapor (superheated steam) by heat exchange with the exhaust gas.

[0032] <Power generation facilities> The power generation facility 4 shown in Fig. 1 generates power by utilizing heat obtained in the heat exchange section of the boiler 13, and also generates power by utilizing the biogas obtained in the fermentation device 8. That is, the power generation facility 4 includes a steam turbine 21 and a generator 22, and is configured to rotate the steam turbine 21 with superheated steam from the boiler 13, and generate power by the generator 22 connected to the steam turbine 21 so as to be capable of transmitting rotational power. The power generation facility 4 further includes a gas engine 23 and a generator 24, and is configured to generate power by driving the generator 24 with the gas engine 23 using biogas (combustible gas) from the fermentation device 8 as fuel. The generators 22 and 24 supply the generated power to the water electrolysis device 5, as well as to power consumers and a power storage device.

[0033] <Water electrolysis device> The water electrolysis device 5 receives power from the generators 22 and 24 and electrolyzes water to generate hydrogen gas and oxygen gas. Although detailed explanation using drawings is omitted for the water electrolysis device 5, for example, the water electrolysis device 5 may include a water tank for storing water, a diaphragm arranged in the water tank so as to divide the inside of the water tank into a first chamber and a second chamber and having gas barrier properties and ion permeability, an anode arranged in the first chamber, and a cathode arranged in the second chamber, and is configured to generate oxygen gas on the anode side and hydrogen gas on the cathode side at the same time by passing a current between the anode and the cathode. Note that the water to be electrolyzed in the water electrolysis device 5 may be water supplied from a water supply source outside the combustion facility 1, but hydrogen gas and oxygen gas can be economically generated by using, for example, drain water discharged from the steam turbine 21 or drain water discharged from the cooling tower 14.

[0034] <Hydrogen storage and supply device> A hydrogen storage and supply device 6 is connected to the water electrolysis device 5 so as to be able to supply the generated hydrogen gas. The hydrogen storage and supply device 6 stores the hydrogen gas supplied from the water electrolysis device 5 and supplies the stored hydrogen gas to hydrogen demanders (including the ammonia reforming combustion system 30). Although detailed explanation using drawings is omitted, the hydrogen storage and supply device 6 may, for example, be equipped with a hydrogen gas tank, a booster, and a pressure reducing valve, and configured to store the hydrogen gas supplied from the water electrolysis device 5 in a pressurized state in the hydrogen gas tank through the booster, and to supply the compressed hydrogen gas stored in the hydrogen gas tank to hydrogen demanders after reducing the pressure to a predetermined pressure with the pressure reducing valve. Other hydrogen storage and supply devices 6 may be configured such that a hydrogen storage alloy absorbs and retains hydrogen gas in a hydrogen storage alloy tank. The hydrogen storage and supply device 6 may take the form of, for example, a container containing components (such as a hydrogen gas tank, a booster, and a pressure reducing valve) that can be packaged and transported by a vehicle or the like (the same applies to the oxygen storage and supply device 7 described later).

[0035] <Oxygen storage and supply device> An oxygen storage and supply device 7 is connected to the water electrolysis device 5 so as to be able to supply the generated oxygen gas. The oxygen storage and supply device 7 stores the oxygen gas supplied from the water electrolysis device 5, supplies the stored oxygen gas to oxygen demand destinations (including the ammonia reforming combustion system 30) and also supplies it to the combustion furnace 2. Although detailed explanation using drawings is omitted, the oxygen storage and supply device 7 may, for example, be one that includes an oxygen gas tank, a booster, and a pressure reducing valve, and is configured to store the oxygen gas supplied from the water electrolysis device 5 in a pressurized state in the oxygen gas tank through the booster, and to reduce the pressure of the compressed oxygen gas stored in the oxygen gas tank to a predetermined pressure using the pressure reducing valve, and then supply it to the oxygen demand destination and the combustion furnace 2. By supplying the oxygen gas from the oxygen storage and supply device 7 to the combustion furnace 2, the amount of combustion supporting gas in the combustion furnace 2 is relatively increased, so that not only is the combustion in the combustion furnace 2 stable, but the amount of unburned gas can be reduced, and the proportion of nitrogen in the combustion furnace 2 can be relatively reduced, thereby suppressing the generation of NOx.

[0036] <Fermentation equipment> The fermentation apparatus 8 includes a fermentation tank 8a for storing a fermentation liquid obtained by fermenting biomass (organic resource derived from living organisms), a biomass supply unit 8b for supplying biomass to the fermentation tank 8a, and a gas supply means 8c for supplying hydrogen gas to the fermentation liquid stored in the fermentation tank 8a. Examples of the biomass supplied from the biomass supply unit 8b to the fermentation tank 8a include organic waste such as food waste, manure, sludge, food processing residues, livestock waste, waste oil, animal oils and fats, and agricultural crop residues.

[0037] The fermenter 8a produces biogas containing methane and the like by fermenting (anaerobic fermentation) biomass such as organic waste, and performs a solubilization process using hydrolytic bacteria and acid-producing bacteria, and a methane fermentation process using methanogens. Examples of the fermenter 8a include a single-tank fermenter in which the solubilization process and the methane fermentation process are performed in a single tank, a plug-flow fermenter in which the solubilization process and the methane fermentation process are performed while the biomass is flowing in the lateral direction, and a two-stage fermenter including an acid fermenter in which the solubilization process is performed in the first stage and a methane fermenter in which the methane fermentation process is performed in the second stage of the acid fermenter. The biogas produced in the fermenter 8a mainly contains methane gas and carbon dioxide gas, and the methane concentration in the biogas is about 50 to 60 vol%.

[0038] Although detailed explanation in the drawings is omitted, the biomass supply unit 8b is configured to include a pressure pump that pressure-feeds the organic waste, a control valve that controls the pressure-feed amount and pressure, and a biomass supply pipe that connects the pressure pump to the fermenter. Note that, before the biomass supply unit 8b, the organic waste as the raw material is subjected to processing such as homogenization of the raw material by removing foreign matter and adjustment to a moisture content suitable for methane fermentation in a pre-processing facility not shown. The organic waste that has been subjected to such pre-processing is supplied to the fermenter 8a by the biomass supply unit 8b.

[0039] The gas supply means 8c includes a hydrogen storage and supply device 6 and a gas supply pipe 8d that supplies the hydrogen gas stored in the hydrogen storage and supply device 6 to the fermentation liquid stored in the fermentation tank 8a. In this way, the hydrogen gas from the hydrogen storage and supply device 6 is supplied by the gas supply means 8c to the fermentation liquid in the fermentation tank 8a, so that the hydrogen gas supplied by the gas supply means 8c is contained in the fermentation liquid in addition to the hydrogen generated by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria. Then, the hydrogen derived from the hydrogen gas supplied by the gas supply means 8c and the carbon dioxide inevitably generated by the decomposition of low-molecular-weight organic matter by the acid-producing bacteria are used as substrates to produce CO2 by the hydrogen-assimilating methanogens. 2 Methane is produced by the reductive methanogenesis reaction. In this way, carbon dioxide is reduced with hydrogen, and the methane concentration in the biogas can be increased from about 50 vol% to about 80 vol% in this example.

[0040] Although detailed description by drawings is omitted, the fermenter 8a may have an acid fermentation zone and a methane fermentation zone. In the acid fermentation zone, an acid production reaction is carried out by acid-producing bacteria to decompose organic matter into lower organic acids such as butyric acid, propionic acid, and acetic acid. On the other hand, in the methane fermentation zone, a methane production reaction is carried out by methanogens to produce methane from acetic acid, hydrogen components, and carbon dioxide components. When hydrogen gas from the gas supply means is supplied to the acid fermentation zone in the fermenter, hydrogen derived from the hydrogen gas supplied by the gas supply means accumulates in addition to hydrogen produced as a by-product in the acid production reaction carried out in the acid fermentation zone, and the hydrogen partial pressure increases. As a result, the acetic acid production reaction does not proceed due to product inhibition, and the methane production rate may decrease. Therefore, it is preferable that the gas supply means 8c supplies hydrogen gas to the methane fermentation zone. By doing so, product inhibition can be avoided in the acid fermentation zone. As a result, in the methane fermentation zone, methane is produced by the acetic acid decomposition methane production reaction using acetic acid as a substrate, and CO2 is produced using hydrogen and carbon dioxide as substrates. 2 Methane is produced by the reductive methanation reaction, and the efficiency of methane production can be improved.

[0041] <Biogas storage and supply device> A biogas storage and supply device 9 is connected to the fermentation tank 8a so as to be able to supply the generated biogas. The biogas storage and supply device 9 stores the biogas supplied from the fermentation tank 8a, supplies the stored biogas to biogas demand destinations (including the ammonia reforming combustion system 30), and also supplies it to the carbon dioxide recovery device 10. Although detailed description by illustration is omitted for the biogas storage and supply device 9, for example, it includes a biogas tank, a booster, and a pressure reducing valve, stores the biogas supplied from the fermentation tank 8a in the biogas tank in a pressurized state through the booster, and after reducing the pressure of the biogas stored in the biogas tank to a predetermined pressure with the pressure reducing valve, supplies it to the biogas demand destinations and the carbon dioxide recovery device 10.

[0042] <Carbon dioxide recovery device> The carbon dioxide recovery device 10 recovers carbon dioxide from the exhaust gas after treatment such as dust removal treatment in the exhaust gas treatment facility 3, and also recovers carbon dioxide from the biogas from the biogas storage and supply device 9. Examples of the carbon dioxide recovery device 10 include devices using chemical absorption method, membrane separation method, physical absorption method, solid absorption method, etc. The carbon dioxide recovery device 10 using the chemical absorption method uses, for example, an amine absorption liquid, and is configured to chemically bond (react) carbon dioxide in the exhaust gas and carbon dioxide in the biogas with the amine to separate and recover only carbon dioxide. The carbon dioxide recovery device 10 using the membrane separation method is configured to use a solid thin film having a separation function and utilize its permeation selectivity to separate and recover carbon dioxide from the exhaust gas. The carbon dioxide recovery device 10 using the physical absorption method is configured to separate and recover carbon dioxide by dissolving it in a liquid. The carbon dioxide recovery device 10 using the solid absorption method uses zeolite, activated carbon, etc. as an adsorbent for physical adsorption, or an inorganic porous material supporting an alkali metal or amines as an adsorbent for chemical adsorption, and is configured to adsorb carbon dioxide in the exhaust gas to the adsorbent for separation and recovery.

[0043] The carbon dioxide capture device 10 captures carbon dioxide from the biogas that is supplied from the biogas storage and supply device 9 and contains mainly methane gas and carbon dioxide gas, supplies a portion of the captured carbon dioxide to the reduction device 11, and supplies the remainder to a carbon dioxide demand destination. Then, the biogas (biogas-derived methane gas) from which the carbon dioxide has been captured by the carbon dioxide capture device 10 is supplied to a methane storage and supply device 12.

[0044] <Reducing device> The reduction device 11 is connected so that carbon dioxide gas can be supplied from the carbon dioxide capture device 10. In the reduction device 11, the carbon dioxide gas from the carbon dioxide capture device 10 is reduced to methane with hydrogen gas supplied from the hydrogen storage and supply device 6.

[0045] The reduction device 11 may be, for example, one that includes a reaction tower filled with a catalyst suitable for the reduction reaction of carbon dioxide to methane. Here, the catalyst may be, for example, a catalyst in which at least one metal selected from nickel, ruthenium, and rhodium is supported on a heat-resistant inorganic oxide carrier such as alumina. Preferably, a ruthenium catalyst in which ruthenium is supported on a porous alumina carrier is used. In this case, since the catalyst exhibits sufficient methanation activity at about 250 to 300°C, it is preferable to adjust the temperature in the reaction tower to about 250 to 300°C by a temperature adjustment means (not shown).

[0046] <Methane storage and supply equipment> The methane storage and supply device 12 stores the biogas-derived methane gas supplied from the carbon dioxide capture device 10 and also stores the methane gas generated in the reduction device 11, and supplies this mixed methane gas to a methane consumer (including the ammonia reforming combustion system 30). Although detailed explanation using drawings is omitted as the methane storage and supply device 12, for example, the device may be equipped with a methane gas tank, a booster, and a pressure reducing valve, and configured to store the biogas-derived methane gas supplied from the carbon dioxide capture device 10 and the methane gas generated in the reduction device 11 in a pressurized state in the methane gas tank through the booster, and to reduce the mixed methane gas stored in the methane gas tank to a predetermined pressure using the pressure reducing valve, and then supply the mixed methane gas to a methane consumer.

[0047] First Embodiment Fig. 2 is a block diagram showing a schematic configuration of an ammonia reforming combustion system 30A according to a first embodiment of the present invention. As shown in Fig. 2, the ammonia reforming combustion system 30A includes an ammonia gas supply device 31, a reformer 32, a combustor 33, a reforming air supply device 34, a combustion air supply device 35, and a control device 36.

[0048] <Ammonia gas supply device> As the ammonia gas supply device 31, for example, one including an ammonia tank and a vaporizer can be used. The ammonia tank stores ammonia, which is a fuel, in a liquid state. The vaporizer vaporizes the ammonia, which is a liquid state stored in the ammonia tank, to generate ammonia gas, which is a fuel gas.

[0049] The ammonia gas supply device 31 and the reformer 32 are connected by an ammonia gas supply pipe 40. An upstream flow control valve 41 and a downstream flow control valve 42 are interposed in this order in the ammonia gas supply pipe 40 from the upstream side to the downstream side of the ammonia gas flow.

[0050] <Reformer> The reformer 32 includes a catalyst 45, and the catalyst 45 is incorporated in a casing. The catalyst 45 is a composite catalyst (catalyst heat-resistant temperature: about 700 °C) that combines a combustion catalyst 46 for burning ammonia (4NH 3 + 3O 2 → 2N 2 + 6H 2 O) and a reforming catalyst 47 disposed on the downstream side of the combustion catalyst 46 in the mixed gas flow for decomposing ammonia into hydrogen and nitrogen (2NH 3 → N 2 + 3H 2 ). As the catalyst 45, for example, known composite catalysts disclosed in JP-A-2010-215457, JP-A-2018-1095, JP-A-2018-1096, JP-A-2021-130100, etc. can be used. The reformer 32 reforms the ammonia gas by passing a mixed gas of the ammonia gas supplied by the ammonia gas supply device 31 and the reforming air supplied by the reforming air supply device 34 through the catalyst 45, and utilizes the heat of the high-temperature gas generated by the combustion of the mixed gas to generate a reformed gas containing hydrogen.

[0051] The reformer 32 and the combustor 33 are connected by a reformed gas supply pipe 50. The reformed gas supply pipe 50 is composed of a relatively short straight pipe for directly introducing the reformed gas from the reformer 32 into the combustor 33 without cooling it, and a heat insulating material 51 is attached to the outer surface side thereof. Thus, the reformed gas from the reformer 32 is introduced into the combustor 33 so as to maintain the temperature of the reformed gas at a relatively high temperature (about 500 to 700 °C) generated in the reformer 32. With such a configuration, the heat energy of the reformed gas is utilized in the combustor 33 without loss, so that the calorific value generated in the combustor 33 can be improved.

[0052] <Combustor> The combustor 33 burns a mixed gas of the reformed gas generated by the reformer 32 and the combustion air supplied from the combustion air supply device 35, and generates high-temperature (about 1500 °C) combustion exhaust gas for shifting to a predetermined combustion state, for example, at the start-up of the combustion furnace 2 stopped during regular inspection or the like.

[0053] <Air supply device for reforming> The air supply device 34 for reforming includes a reforming air blower 55 that forcibly sends the taken-in outside air (atmospheric air) as reforming air, and a reforming air supply pipe 56 for supplying the reforming air sent out from the reforming air blower 55 to the reformer 32. The reforming air blower 55 mainly includes a blower main body 57, a motor 58 connected to the blower main body 57, and an inverter 59 that controls the rotation speed of the motor 58. In the reforming air supply pipe 56, the upstream end of the reforming air flow is connected to the air outlet of the reforming air blower 55, and the downstream end of the reforming air flow is connected in a communicating state to a portion between the upstream flow control valve 41 and the downstream flow control valve 42 in the ammonia gas supply pipe 40. In the air supply device 34 for reforming, the control device 36, more specifically, a control signal sent from the blower control unit 82 described later to the inverter 59 controls the air volume of the reforming air blower 55, that is, the supply volume (Q1) of the reforming air. A tachometer 60 for measuring the rotation speed is attached to the motor 58, and the measurement signal of the tachometer 60 is sent to the control device 36. The blower control unit 82 described later compares the measured value measured by the tachometer 60 with the target value, and sends a control signal corresponding to the difference between the measured value and the target value to the inverter 59 to control the measured value to match the target value. In the air supply device 34 for reforming, the inverter 59 may be omitted, and the rotation speed of the motor 58 may be set to a constant value to send out a predetermined air volume by a control signal sent from the blower control unit 82 to the motor 58. At the same time, a flow control damper may be provided in the reforming air supply pipe 56, and the air volume of the reforming air blower 55 (the supply volume (Q1) of the reforming air) may be controlled by a control signal sent from the blower control unit 82 to the flow control damper.

[0054] <Combustion air supply device> The combustion air supply device 35 includes a combustion air fan 65 that forcibly discharges the taken-in outside air (atmospheric air), a combustion air supply pipe 66 for supplying the combustion air sent out from the combustion air fan 65 to the combustor 33, and a flow rate adjustment damper 70 provided in the combustion air supply pipe 66. The combustion air fan 65 mainly includes a fan main body 67 and a motor 68 connected to the fan main body 67, and is configured to send out a predetermined air volume with a constant rotational speed of the motor 68 according to a control signal sent from the control device 36, more specifically, a fan control unit 83 described later. In the combustion air supply pipe 66, the upstream end of the combustion air flow is connected to the air outlet of the combustion air fan 65, and the downstream end of the combustion air flow is connected to the combustor 33. In the combustion air supply device 35, the supply air volume of the combustion air fan 65, that is, the supply amount (Q3) of the combustion air, is controlled by a control signal sent from the control device 36, more specifically, a damper control unit 84 described later, to the flow rate adjustment damper 70. In addition, in the combustion air supply device 35, while an inverter is attached to the motor 68, the flow rate adjustment damper 70 may be omitted, and the supply air volume (supply amount (Q3) of the combustion air) of the combustion air fan 65 may be controlled by a control signal sent from the fan control unit 83 to the inverter.

[0055] The control device 36 is mainly composed of a computer and includes functional units such as a measurement unit 81, a blower control unit 82, a fan control unit 83, a damper control unit 84, and a valve control unit 85, and is configured such that the functions of the respective functional units are exerted when a predetermined program is executed by the CPU.

[0056] The ammonia reforming combustion system 30A further includes a gas flow meter 91, a gas pressure gauge 92, a gas thermometer 93, an oxygen concentration meter 94, and a combustor thermometer 95.

[0057] <Gas flow meter> The gas flow meter 91 is arranged to measure the flow rate of ammonia gas flowing inside the pipe section between the position where the upstream flow control valve 41 in the ammonia gas supply pipe 40 is installed and the position where the downstream end of the reforming air supply pipe 56 is connected. The measurement signal of the gas flow meter 91 is sent to the control device 36 via the flow regulator 96. Here, the flow regulator 96 compares the measured value measured by the gas flow meter 91 with the target value (indicated value), and sends a control signal corresponding to the difference between the measured value and the target value to the upstream flow control valve 41 to perform control so that the measured value matches the target value.

[0058] <Gas pressure gauge> The gas pressure gauge 92 is arranged to measure the pressure of ammonia gas flowing inside the pipe section between the position where the gas flow meter 91 in the ammonia gas supply pipe 40 is installed and the position where the downstream end of the reforming air supply pipe 56 is connected. The measurement signal of the gas pressure gauge 92 is sent to the control device 36.

[0059] <Gas thermometer> The gas thermometer 93 is arranged to measure the gas temperature of the reformed gas (reformed gas temperature: substantially the temperature of the catalyst 45) flowing inside the upstream pipe section near the outlet of the reformer 32 in the reformed gas supply pipe 50. The measurement signal of the gas thermometer 93 is sent to the control device 36.

[0060] <Oxygen concentration meter> The oxygen concentration meter 94 is arranged downstream of the gas thermometer 93 in the flow direction of the reformed gas to measure the concentration of oxygen contained in the reformed gas flowing inside the reformed gas supply pipe 50 (oxygen concentration in the reformed gas). The measurement signal of the oxygen concentration meter 94 is sent to the control device 36.

[0061] <Combustor thermometer> The combustor thermometer 95 is attached to the combustor 33 to measure the combustion temperature (combustor temperature) inside the combustor 33. The measurement signal of the combustor thermometer 95 is sent to the control device 36.

[0062] <Gas information, gas information acquisition means> In the control device 36, based on the measurement signals of the gas flow meter 91, the gas pressure gauge 92, the gas thermometer 93, the oxygen concentration meter 94, and the combustor thermometer 95, the measurement unit 81 measures the flow rate, pressure, reformed gas temperature, oxygen concentration contained in the reformed gas, and the combustion chamber temperature (combustion gas temperature) of the combustor 33 of the ammonia gas. The above-mentioned flow rate and pressure of the ammonia gas, as well as the temperature and oxygen concentration of the reformed gas, are information regarding the gas flowing through the gas flow path from the ammonia gas supply device 31 through the reformer 32 to the combustor 33. In the present embodiment, the gas information acquisition means for acquiring gas information mainly includes a measurement means (gas flow meter 91, gas pressure gauge 92, gas thermometer 93, oxygen concentration meter 94, and combustor thermometer 95) and a measurement unit 81.

[0063] <Reforming air supply amount control means> Based on the measurement means (gas flow meter 91 and gas thermometer 93) and the gas information obtained by the measurement unit 81, the blower control unit 82 controls the ratio (Q1 / Q2) of the supply amount (Q1) of the reforming air to the supply amount (Q2) of the ammonia gas to be within a predetermined range, and / or the temperature of the high-temperature gas generated by the combustion of the mixed gas of the ammonia gas and the reforming air (measured by the gas thermometer 93 near the outlet of the reformer 32) to be within a predetermined temperature range, and transmits a predetermined control signal to the inverter 59 of the reforming air blower 55 to control the air volume of the reforming air blower 55, that is, the supply amount (Q1) of the reforming air. In the present embodiment, the reforming air supply amount control means for controlling the supply amount (Q1) of the reforming air supplied by the reforming air supply device 34 based on the gas information mainly includes an inverter 59 and a blower control unit 82.

[0064] <Combustion air supply amount control means> The fan control unit 83 transmits a control signal to the motor 68 of the combustion air fan 65, and controls the rotation speed of the motor 68 to be constant so as to send out a predetermined air volume. The damper control unit 84, based on the gas information acquired by the measuring means (gas flow meter 91) and the measuring unit 81, transmits a predetermined control signal to the flow rate adjustment damper 70 so that the ratio (Q3 / Q2) of the supply amount (Q3) of the combustion air to the supply amount (Q2) of the ammonia gas falls within a predetermined range, controls the opening degree of the flow rate adjustment damper 70, and controls the supply amount (Q3) of the combustion air. In the present embodiment, the combustion air supply amount control means for controlling the supply amount (Q3) of the combustion air supplied by the combustion air supply device 35 based on the gas information mainly includes the flow rate adjustment damper 70, the fan control unit 83, and the damper control unit 84.

[0065] <Combustion promotion gas supply device, combustion promotion gas supply amount control means> The ammonia reforming combustion system 30A further includes a combustion promotion gas supply device 100 that supplies a combustible gas and an oxidant gas to the combustor 33, and a combustion promotion gas supply amount control means 150 that controls the supply amounts of the combustible gas and the oxidant gas based on the combustion temperature of the combustor 33. The combustion promotion gas supply device 100 is composed of a combustible gas supply device 110 and an oxidant gas supply device 130. The combustion promotion gas supply amount control means 150 is composed of a combustible gas supply amount control means 160 and an oxidant gas supply amount control means 180.

[0066] <Combustible gas supply device> The combustible gas supply device 110 includes a combustible gas storage supply device 111 and a combustible gas supply pipe 112. As the combustible gas storage supply device 111, for example, a hydrogen storage supply device 6, a biogas storage supply device 9, a methane storage supply device 12, etc. can be used. In this example, a hydrogen storage supply device 6 is used as the combustible gas storage supply device 111. In this way, by using the hydrogen gas generated by electrolyzing water with a water electrolysis device 5 using the electric power generated by a power generation facility 4 using the heat obtained by heat exchange with exhaust gas in the boiler 3 of the combustion facility 1 as the combustible gas, it is not necessary to separately procure the combustible gas from outside the combustion facility 1, and the procurement cost of the combustible gas can be reduced. In addition, by effectively utilizing the exhaust heat of the combustion facility 1, not only can direct carbon dioxide be reduced, but also since the treatment can be completed within the combustion facility 1, carbon dioxide generated secondarily due to fuel transportation, etc. can also be reduced, thus contributing to decarbonization (the same applies to oxidant gas, etc.). Note that even when a biogas storage supply device 9 or a methane storage supply device 12 is used as the combustible gas storage supply device 111, since biogas or methane gas is generated within the combustion facility 1, it is not necessary to separately procure the combustible gas from outside the combustion facility 1, and the procurement cost of the combustible gas can be reduced. Needless to say, as the combustible gas storage supply device 111, a gas storage supply device including a combustible gas tank that stores commercially available combustible gas can be used.

[0067] The combustible gas storage supply device 111 and the combustor 33 are connected by a combustible gas supply pipe 112, and the combustible gas (hydrogen gas) from the combustible gas storage supply device 111 is supplied into the interior (combustion chamber) of the combustor 33 through the combustible gas supply pipe 112.

[0068] <Oxidant Gas Supply Device> The oxidant gas supply device 130 includes an oxidant gas storage and supply device 131 and oxidant gas supply pipes 132 and 133. As the oxidant gas storage and supply device 131, for example, an oxygen storage and supply device 7, an air storage and supply device (not shown), an air compressor, etc. can be used. In this example, the oxygen storage and supply device 7 is used as the oxidant gas storage and supply device 131. In this way, by using the oxygen gas generated by electrolyzing water with the water electrolysis device 5 using the electric power generated by the power generation facility 4 using the heat obtained by heat exchange with the exhaust gas in the boiler 3 of the combustion facility 1, it is not necessary to separately procure the oxidant gas from outside the combustion facility 1, and the procurement cost of the oxidant gas can be reduced. Needless to say, as the oxidant gas storage and supply device 131, a gas storage and supply device including an oxidant gas tank for storing commercially available oxidant gas can be used.

[0069] The oxidant gas storage and supply device 131 and the combustion air supply pipe 66 are connected by the oxidant gas supply pipe 132. More specifically, in the oxidant gas supply pipe 132, the upstream end of the oxidant gas flow is connected to the oxidant gas storage and supply device 131, and the downstream end of the oxidant gas flow is connected in a communicating state to a portion between the flow rate adjustment damper 70 and the combustor 33 in the combustion air supply pipe 66. In this way, the oxidant gas from the oxidant gas storage and supply device 131 is supplied to the inside (combustion chamber) of the combustor 33 via the oxidant gas supply pipe 132 and the combustion air supply pipe 66.

[0070] Further, the oxidant gas storage and supply device 131 and the ammonia gas supply pipe 40 are connected by an oxidant gas supply pipe 133. More specifically, in the oxidant gas supply pipe 133, the upstream end of the oxidant gas flow is connected to the oxidant gas storage and supply device 131, and the downstream end of the oxidant gas flow is at a position between the upstream flow control valve 41 and the downstream flow control valve 42 in the ammonia gas supply pipe 40, and is connected in a communicating state upstream of the ammonia gas flow with respect to the position where the downstream end of the reforming air flow in the reforming air supply pipe 56 is connected. Thus, the oxidant gas from the oxidant gas storage and supply device 131 is supplied to the catalyst 45 inside the reformer 32 via the oxidant gas supply pipe 133 and the ammonia gas supply pipe 40.

[0071] <Flammable gas supply amount control means> The flammable gas supply amount control means 160 includes a measurement unit 81, a damper control unit 84, a combustor thermometer 95, a flow control damper 161, and a gas flow meter 162. Here, the flow control damper 161 is provided in the middle of the flammable gas supply pipe 112. Further, the gas flow meter 162 is arranged to measure the flow rate (flammable gas supply amount) of the flammable gas flowing from the flow control damper 161 in the flammable gas supply pipe 112 to the combustor 33. The measurement signal of the gas flow meter 162 is sent to the control device 36.

[0072] <Oxidant gas supply amount control means> The oxidizing agent gas supply amount control means 180 includes a measurement unit 81, a damper control unit 84, an oxygen concentration meter 94, a combustor thermometer 95, flow control dampers 181 and 182, and gas flow meters 183 and 184. Here, the flow control damper 181 is installed in the middle of the oxidizing agent gas supply pipe 132, and the flow control damper 182 is installed in the middle of the oxidizing agent gas supply pipe 133. Also, the gas flow meter 183 is arranged to measure the flow rate of the oxidizing agent gas (oxidizing agent gas supply amount) flowing from the flow control damper 181 in the oxidizing agent gas supply pipe 132 to the combustion air supply pipe 66, and the gas flow meter 184 is arranged to measure the flow rate of the oxidizing agent gas (oxidizing agent gas supply amount) flowing from the flow control damper 182 in the oxidizing agent gas supply pipe 133 to the ammonia gas supply pipe 40. The measurement signals of the gas flow meters 183 and 184 are sent to the control device 36.

[0073] In the combustion promoting gas supply amount control means 150, the damper control unit 84 sets a predetermined combustion temperature within an appropriate combustion temperature range as the target combustion temperature based on the combustion temperature of the combustor 33 acquired by the combustor thermometer 95 and the measurement unit 81, calculates the combustible gas supply amount and the oxidizing agent gas supply amount at which the current combustion temperature acquired by the combustor thermometer 95 and the measurement unit 81 becomes the target combustion temperature, and sends a control signal to the flow control dampers 161 and 181 so that the current combustible gas supply amount and oxidizing agent gas supply amount to the combustor 33 acquired by the gas flow meters 162, 183 and the measurement unit 81 approach the combustible gas supply amount and oxidizing agent gas supply amount calculated by this calculation, and controls the supply amounts of the combustible gas and the oxidizing agent gas supplied to the combustor 33 so as to reach the target combustion temperature.

[0074] Further, in the oxidant gas supply amount control means 180 of the combustion promotion gas supply amount control means 150, the damper control unit 84 sets a predetermined oxygen concentration within an appropriate oxygen concentration range as the target oxygen temperature based on the concentration of oxygen contained in the reformed gas acquired by the oxygen concentration meter 94 and the measurement unit 81, calculates the supply amount of the oxidant gas at which the current oxygen temperature acquired by the oxygen concentration meter 94 and the measurement unit 81 becomes the target oxygen temperature, and sends a control signal to the flow rate adjustment damper 182 so that the current supply amount of the oxidant gas to the reformer 32 acquired by the gas flow meter 184 and the measurement unit 81 approaches the supply amount of the oxidant gas calculated by this calculation, and controls the supply amount of the oxidant gas supplied to the reformer 32.

[0075] In addition, in the present embodiment, the combustion promotion gas supply device 100 has shown an example of a mode of supplying a combustible gas and an oxidant gas to the combustor 33, but there is also an example of a mode of supplying only one of the combustible gas or the oxidant gas, that is, only one of the combustible gas and the oxidant gas, to the combustor 33. In this case, the combustion promotion gas supply device 100 will be constituted by either one of the combustible gas supply device 110 and the oxidant gas supply device 130. Further, in the present embodiment, the combustion promotion gas supply amount control means 150 has shown an example of a mode of controlling the supply amounts of the oxidant gas and the combustible gas based on the combustion temperature of the combustor 33, but there is also an example of a mode of controlling only the supply amount of the oxidant gas or the combustible gas, that is, only one of the combustible gas and the oxidant gas, based on the combustion temperature of the combustor 33. In this case, the combustion promotion gas supply amount control means 150 will be constituted by either one of the combustible gas supply amount control means 160 and the oxidant gas supply amount control means 180.

[0076] 〔Ammonia reforming combustion method〕 Figure 3 is a flowchart showing the operation procedure of the ammonia reforming combustion system 30A. In Figure 3, the symbol "S" represents a step (the same applies in Figures 4 to 6).

[0077] <Ammonia gas supply step, reforming air supply step: S1> In the ammonia reforming combustion system 30A, ammonia gas is supplied from the ammonia gas supply device 31 to the reformer 32 through the ammonia gas supply pipe 40 (ammonia gas supply step). At the same time, reforming air is supplied from the reforming air supply device 34 to the reformer 32 through the reforming air supply pipe 56 and the ammonia gas supply pipe 40 (reforming air supply step).

[0078] <Reforming gas generation step: S2> The reformer 32 uses the heat of the high-temperature gas generated by the combustion of the mixed gas of the ammonia gas supplied from the ammonia gas supply device 31 and the reforming air supplied from the reforming air supply device 34 under the action of the catalyst 45 to reform the ammonia gas and generate a reforming gas containing hydrogen.

[0079] <Reforming gas supply step, combustion air supply step: S3> The reforming gas generated by the reformer 32 is supplied to the combustor 33 through the reforming gas supply pipe 50 (reforming gas supply step), and the combustion air from the combustion air supply device 35 is supplied to the combustor 33 through the combustion air supply pipe 66 (combustion air supply step).

[0080] <Combustion step (combustion exhaust gas generation step): S4> The combustor 33 burns the mixed gas of the reforming gas generated by the reformer 32 and the combustion air supplied by the combustion air supply device 35 to generate high-temperature (about 1500 °C) combustion exhaust gas.

[0081] At the start stage of the operation of the ammonia reforming combustion system as shown in the flowchart of FIG. 3, since the decomposition action of the ammonia gas by the catalyst 45 is insufficient, the undissociated ammonia gas is directly introduced into the combustor 33 without being decomposed by the catalyst 45, and there is a risk of poor combustion in the combustor 33. Therefore, the combustion promotion gas supply amount control step described below is performed.

[0082] FIG. 4 is a flowchart showing the processing procedure of the combustion promotion gas supply amount control step.

[0083] <S11~S12> The measurement unit 81 captures a measurement signal from at least one of the gas thermometer 93, the oxygen concentration meter 94, and the combustor thermometer 95 (S11). Based on the captured measurement signal, the measurement unit 81 measures the measurement target (combustor temperature, reformed gas temperature, oxygen concentration in the reformed gas) (S12).

[0084] <s13> Next, the damper control unit 84 determines whether the measured value of the measurement target exceeds the upper limit value or is less than the lower limit value of the appropriate range (S13). For example, when the measurement target is the gas temperature of the reformed gas, it is determined whether the measured value of the gas temperature of the reformed gas obtained by the gas thermometer 93 and the measurement unit 81 is less than the lower limit value of the appropriate gas temperature range. When the measurement target is the concentration of oxygen contained in the reformed gas, it is determined whether the measured value of the oxygen concentration in the reformed gas obtained by the oxygen concentration meter 94 and the measurement unit 81 exceeds the upper limit value of the appropriate oxygen concentration range. When the measurement target is the combustion temperature of the combustor 33, it is determined whether the measured value of the combustion temperature of the combustor 33 obtained by the combustor thermometer 95 and the measurement unit 81 is less than the lower limit value of the appropriate combustion temperature range.

[0085] <S14~S15> If it exceeds the upper limit value or is less than the lower limit value (``YES'' in step S13), the damper control unit 84 sets a predetermined value within the appropriate measurement value range of the measurement target as the target value, and calculates the amount of combustible gas supply and the amount of oxidant gas supply required for the current measurement value obtained by the measuring instruments 93 to 95 and the measurement unit 81 to reach the target value. A control signal is sent to the flow control dampers 161 and 181 so that the current supply amounts of the combustible gas and the oxidant gas to the combustor 33 obtained by the gas flow meters 162 and 183 and the measurement unit 81 approach the calculated supply amounts of the combustible gas and the oxidant gas (S14), and the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 are controlled so that the measured value reaches the target value (S15).

[0086] In steps S11 to S15, when any one of the combustion temperature, the reformed gas temperature, and the oxygen concentration in the reformed gas is selected as the measurement target, the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 are controlled so that the measured value of the selected one measurement target reaches the target value.

[0087] In steps S11 to S15, when two of the combustor temperature, the reformed gas temperature, and the oxygen concentration in the reformed gas are selected as the measurement targets, it is preferable to control the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 so that the measured values of the two selected measurement targets reach the target values. It can be said that such control is highly reliable as control for stabilizing combustion in the combustor 33. However, it is not limited to this. For example, a priority order may be set for the two selected measurement targets, and the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 may be controlled so that the measured value of the measurement target with the higher priority reaches the target value, that is, a form of control with weighting may be used.

[0088] In steps S11 to S15, when all three of the combustor temperature, the reformed gas temperature, and the oxygen concentration in the reformed gas are selected as the measurement targets, it is preferable to control the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 so that all the measured values of the three selected measurement targets reach the target values. It can be said that such control is the most reliable as control for stabilizing combustion in the combustor 33. However, it is not limited to this. For example, a priority order may be set for the three selected measurement targets, and the supply amounts of the combustible gas and the oxidant gas supplied to the combustor 33 may be controlled so that the measured value of the measurement target with the highest priority reaches the target value, or so that the measured values of the top two measurement targets with the higher priority reach the target values, that is, a form of control with weighting may be used.

[0089] Thus, in a situation where ammonia gas cannot be completely decomposed in the reformer 32 at the start-up stage and the undecomposed ammonia gas is introduced from the reformer 32 into the combustor 33, a combustible gas and an oxidant gas are supplied to the combustor 33. When the combustible gas is supplied to the combustor 33, the combustible gas burns, and since the ammonia gas is ignited by the burned combustible gas, the combustion in the combustor 33 becomes stable. Also, when the oxidant gas is supplied to the combustor 33, the amount of the supporting combustible gas in the combustor 33 relatively increases, so the combustion in the combustor 33 becomes stable. In this way, by supplying both the oxidant gas and the combustible gas to the combustor 33, the combustion in the combustor 33 becomes more stable due to the synergistic effect. Therefore, even in a situation where the undecomposed ammonia gas is introduced into the combustor 33 at the start-up stage, the combustion in the combustor 33 can be stabilized.

[0090] In the reforming air supply process of step S1 in the flowchart of FIG. 3, when the supply amount (Q1) of the reforming air supplied to the reformer 32 is large, the combustion of the mixed gas of ammonia gas and reforming air on the combustion catalyst 46 is promoted and the temperature of the high-temperature gas generated by the combustion rises. Therefore, while promoting the reaction of reforming ammonia gas, the ammonia gas to be reformed is consumed by combustion, so the hydrogen content in the reformed gas decreases as the amount of ammonia gas to be reformed decreases. On the other hand, when the supply amount (Q1) of the reforming air supplied to the reformer 32 is small, the combustion of the mixed gas of ammonia gas and reforming air on the combustion catalyst 46 is suppressed and the temperature of the high-temperature gas generated by the combustion decreases. Therefore, the reaction of reforming ammonia gas does not proceed sufficiently, and the hydrogen content in the reformed gas decreases. Thus, whether the supply amount (Q1) of the reforming air is large or small, the hydrogen content in the reformed gas decreases. Therefore, the reforming air supply amount control process described below is performed.

[0091] FIG. 5 is a flowchart showing the processing procedure of the reforming air supply amount control process.

[0092] <S21~S22> The measurement unit 81 captures the measurement signals from each measurement means (gas flow meter 91, gas thermometer 93, rotational speed meter 60) (S21). Based on the captured measurement signals, the measurement unit 81 measures the flow rate of ammonia gas (supply amount (Q2) of ammonia gas) by the gas flow meter 91 and / or the temperature of the reformed gas by the gas thermometer 93 (S22).

[0093] <S23~S24> The blower control unit 82 outputs a control signal to the inverter 59 so that the ratio (Q1 / Q2) of the supply amount (Q1) of the reforming air supplied by the reforming air blower 55 to the supply amount (Q2) of the ammonia gas measured by the gas flow meter 91 is within a predetermined range, and controls the rotational speed of the motor 58 of the reforming air blower 55 to control the supply amount (Q1) of the reforming air. In the present embodiment, for example, the rotational speed of the motor 58 of the reforming air blower 55 is controlled so that Q1 / Q2 is 0.47 to 1.04.

[0094] Note that between the supply amount Q1 [L / min] of the reforming air, the supply amount Q2 [L / min] of the ammonia gas, the combustion air ratio n, the oxygen concentration in the air (20.95%), and the ratio (0.75) of the oxygen that reacts with ammonia in the chemical reaction formula (4NH 3 +3O 2 →2N 2 +6H 2 O), the relationships of the following formulas (1) and (2) are established. Therefore, when Q1 / Q2 is 0.47 to 1.04, n is 0.13 to 0.29.

[0095]

Equation

[0096] In the combustion air supply process of step S3 in the flowchart of FIG. 3, whether the supply amount (Q3) of the combustion air supplied to the combustor 33 is large or small, combustion becomes unstable in the combustor 33. Therefore, the combustion air supply amount control process described below is performed.

[0097] FIG. 6 is a flowchart showing the procedure of the process for controlling the combustion air supply amount.

[0098] <S31~S32> The measurement unit 81 captures each measurement signal from the gas flow meter 91, the gas thermometer 93, and the oxygen concentration meter 94 (S31). Based on the captured measurement signals, the measurement unit 81 measures the flow rate of the ammonia gas (the supply amount (Q2) of the ammonia gas) by the gas flow meter 91, measures the temperature of the reformed gas by the gas thermometer 93, and measures the concentration of oxygen contained in the reformed gas by the oxygen concentration meter 94 (S32). Note that the supply amount (Q1) of the reforming air is grasped by the blower control unit 82 in real time.

[0099] <S33~S36> The fan control unit 83 transmits a control signal to the motor 68 of the combustion air fan 65 (S33), and controls the motor 68 to keep it at a predetermined rotational speed constantly so as to send out a predetermined air volume. The damper control unit 84 calculates a target value of the supply amount of the combustion air, which is the amount of oxygen to be supplied for stable combustion in the combustor 33, based on the measured values of the supply amount (Q1) of the reforming air, the supply amount (Q2) of the ammonia gas, the measured value of the temperature of the reformed gas, and the measured value of the concentration of oxygen contained in the reformed gas (S34), and outputs a control signal to the flow rate adjustment damper 70 to control the opening degree of the flow rate adjustment damper 70 so that the supply amount (Q3) of the combustion air reaches the target value (S35~S36).

[0100] In this way, since the supply amount (Q3) of the combustion air is controlled to reach the above target value, stable combustion can be performed in the combustor 33.

[0101] During the operation of the ammonia reforming combustion system as shown in the flowchart of FIG. 3, the decomposition of ammonia gas in the reformer 32 may be delayed due to changes in operating conditions or the like, and the un-decomposed ammonia gas may be introduced into the combustor 33, resulting in unstable combustion. In such a case, by performing the combustion promotion gas supply amount control step as shown in the flowchart of FIG. 4, even when the un-decomposed ammonia gas is introduced into the combustor 33 during operation, the combustion in the combustor 33 can be stabilized. Further, in the oxidant gas supply amount control means 180, by controlling the oxygen concentration contained in the reformed gas acquired by the oxygen concentration meter 94 and the measurement unit 81 within an appropriate range, the reforming in the reformer 32 can be stabilized.

[0102] In the combustion exhaust gas generation step of step S4 in the flowchart of FIG. 3, the combustion exhaust gas generated by the combustion in the combustor 33 is introduced into, for example, a wind box provided on the lower side of the afterburning stoker when the combustion furnace 2 is a stoker-type combustion furnace. In this way, by utilizing the combustion heat generated in the combustor 33 at the start-up of the furnace operation, not only can the direct reduction of carbon dioxide due to non-use of fuel be achieved, but also the carbon dioxide generated secondarily due to fuel transportation, etc. can be reduced, so that the total amount of carbon dioxide generated can be significantly reduced.

[0103] 〔Second Embodiment〕 FIG. 7 is a block diagram showing the schematic configuration of an ammonia reforming combustion system 30B according to the second embodiment of the present invention. In the second embodiment, for those that are the same or similar to the first embodiment, the same reference numerals are given in the figure and the detailed description thereof is omitted. Hereinafter, the description will be centered on the parts specific to the second embodiment.

[0104] In the ammonia reforming combustion system 30B of the second embodiment, a pilot burner 200 is attached to the combustor 33, and the combustible gas from the combustible gas supply device 110 is configured to be supplied to the pilot burner 200. Otherwise, it is the same as the ammonia reforming combustion system 30A of the first embodiment, and the processes shown in the flowcharts of FIGS. 3 to 6 are executed in the same manner. Note that by attaching a spark plug (not shown) to the combustor 33 so as to be attached to the pilot burner 200, the pilot burner 200 can be surely ignited inside the combustor 33. In FIG. 7, an example in which one pilot burner 200 is provided for the combustor 33 is shown, but the present invention is not limited to this, and a plurality of pilot burners 200 may be appropriately arranged and provided at a plurality of locations for the combustor 33.

[0105] Also in the ammonia reforming combustion system 30B of the second embodiment, in a situation where ammonia gas cannot be completely decomposed in the reformer 32 due to changes in the operating conditions at the start of operation or during operation, and the undecomposed ammonia gas is introduced from the reformer 32 into the combustor 33, the combustible gas is supplied to the pilot burner 200 attached to the combustor 33. When the combustible gas is supplied to the pilot burner 200, the combustible gas ejected from the pilot burner 200 into the combustor 33 burns to form a flame, and the flame of the pilot burner 200 transfers fire to the ammonia gas, so the combustion in the combustor 33 becomes stable. Therefore, even in a situation where undecomposed ammonia gas is introduced into the combustor 33 due to changes in the operating conditions at the start of operation or during operation, the combustion in the combustor 33 can be stabilized. Note that the effect of supplying the oxidant gas is the same as that of the first embodiment.

[0106] As described above, the ammonia reforming combustion system of the present invention has been described based on a plurality of embodiments. However, the present invention is not limited to the configurations described in the above embodiments, and the configuration can be appropriately changed without departing from the spirit thereof.

Industrial Applicability

[0107] The ammonia reforming combustion system of the present invention can be used, for example, for burning combustibles during the startup of a combustion furnace or a boiler.

Explanation of Signs

[0108] 1 Combustion facility 30 Ammonia reforming combustion system 31 Ammonia gas supply device 32 Reformer 33 Combustor 34 Air supply device for reforming 35 Air supply device for combustion 100 Combustion promoting gas supply device 110 Combustible gas supply device 130 Oxidant gas supply device 150 Combustion promoting gas supply amount control means 160 Combustible gas supply amount control means 180 Oxidant gas supply amount control means 200 Pilot burner

Claims

1. An ammonia reforming combustion system comprising an ammonia gas supply device for supplying ammonia gas, a reforming air supply device for supplying reforming air, and a combustion air supply device for supplying combustion air, wherein a reformer that reforms the ammonia gas by using the heat of high-temperature gas generated by the combustion of a mixed gas of the ammonia gas supplied by the ammonia gas supply device and the reforming air supplied by the reforming air supply device to generate a reformed gas containing hydrogen; a combustor that combusts a mixed gas of the reformed gas generated by the reformer and the combustion air supplied by the combustion air supply device; a combustion promoting gas supply device that supplies a combustible gas and / or an oxidant gas to the combustor; An ammonia reforming combustion system comprising the above.

2. The ammonia reforming combustion system according to claim 1, further comprising combustion promoting gas supply amount control means for controlling the supply amount of the combustible gas and / or the oxidant gas based on at least one of the combustion temperature of the combustor, the gas temperature of the reformed gas, and the concentration of oxygen contained in the reformed gas.

3. The combustible gas and / or the oxidant gas is hydrogen gas and / or oxygen gas generated by electrolyzing water with electric power generated by using the heat obtained by heat exchange with exhaust gas in a combustion facility, according to claim 1 or 2 of the ammonia reforming combustion system.

4. An ammonia reforming combustion system comprising an ammonia gas supply device for supplying ammonia gas, a reforming air supply device for supplying reforming air, and a combustion air supply device for supplying combustion air, wherein a reformer that reforms the ammonia gas by using the heat of high-temperature gas generated by the combustion of a mixed gas of the ammonia gas supplied by the ammonia gas supply device and the reforming air supplied by the reforming air supply device to generate a reformed gas containing hydrogen; a combustor that combusts a mixed gas of the reformed gas generated by the reformer and the combustion air supplied by the combustion air supply device; a pilot burner attached to the combustor; a combustible gas supply device that supplies a combustible gas to the pilot burner; An ammonia reforming combustion system comprising the above.

5. The ammonia reforming combustion system according to claim 4, further comprising combustible gas supply amount control means for controlling the supply amount of the combustible gas based on the combustion temperature of the combustor.

6. The ammonia reforming combustion system according to claim 4, comprising an oxidant gas supply device for supplying an oxidant gas to the combustor.

7. The ammonia reforming combustion system according to claim 6, comprising an oxidant gas supply amount control means for controlling the supply amount of the oxidant gas based on the combustion temperature of the combustor.

8. The ammonia reforming combustion system according to any one of claims 4 to 7, wherein the combustible gas is hydrogen gas generated by electrolyzing water with electric power generated by using heat obtained by heat exchange with exhaust gas in a combustion facility.

9. The ammonia reforming combustion system according to claim 6 or 7, wherein the oxidant gas is oxygen gas generated by electrolyzing water with electric power generated by using heat obtained by heat exchange with exhaust gas in a combustion facility.

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