Fuel preheater

Abstract

A fuel preheater (10) includes: a first mixer (1) which is provided to a fuel supply line (L1) connected to combustion facilities (100) for burning a fuel including ammonia, the fuel supply line (L1) supplying ammonia to the first mixer (1), the first mixer (1) being connected to an oxidizing-agent supply line (L2) for oxidizing-agent supply and mixing the ammonia flowing through the fuel supply line (L1) with the oxidizing agent from the oxidizing-agent supply line (L2), thereby forming a mixture gas; and a reactor (2) provided downstream from the first mixer (1) in the fuel supply line (L1) and containing a catalyst which accelerates an ammonia reaction to cause an exothermic reaction, the catalyst causing the exothermic reaction due to at least some of the ammonia contained in the mixture gas supplied from the first mixer (1), thereby heating the mixture gas.

Description

Fuel Preheater

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-097818, filed on June 14, 2023, the contents of which are incorporated herein by reference.

[0002] In combustion facilities, catalysts are sometimes used to promote combustion. For example, Patent Document 1 discloses a catalytic flameless combustion device. In this device, a mixture of air and natural gas is combusted on a catalyst packed in a combustion chamber.

[0003] Furthermore, Patent Document 2 discloses a catalytic combustion burner in which a mixture of air and a gaseous fuel such as natural gas or city gas is combusted over a catalyst.

[0004] Patent Document 3 also discloses a burner portion of a gas turbine, in which a mixture of natural gas and air is oxidized by a catalyst and then combusted in a pilot flame and a main flame.

[0005] JP 2019-511696 A JP 2019-529847 A JP 11-509307 A

[0006] Ammonia is CO ２ However, the combustion rate of ammonia is slower than that of other fuels, such as natural gas. Therefore, when using ammonia in combustion equipment, it is desirable to increase the combustion rate of ammonia.

[0007] An object of the present disclosure is to provide a fuel preheater that can supply fuel to a combustion facility at an increased combustion rate when ammonia is used as fuel in the combustion facility, and to provide a method for installing such a fuel preheater in the combustion facility.

[0008] A fuel preheater according to one aspect of the present disclosure includes: a first mixer provided in a fuel supply line connected to combustion equipment that combusts a fuel containing ammonia, the fuel supply line supplying ammonia to the first mixer; the first mixer being connected to an oxidant supply line that supplies an oxidant, and mixing the ammonia flowing through the fuel supply line with the oxidant from the oxidant supply line to generate a mixed gas; and a reactor provided downstream of the first mixer in the fuel supply line, the reactor including a catalyst that promotes a reaction of ammonia to cause an exothermic reaction, the catalyst causing an exothermic reaction by at least a portion of the ammonia in the mixed gas supplied from the first mixer, thereby heating the mixed gas.

[0009] The fuel preheater may include a second mixer provided downstream of the reactor in the fuel supply line, the second mixer connected to the oxidant supply line by a first bypass line, and mixing the mixed gas supplied from the reactor with the oxidant supplied from the first bypass line.

[0010] The fuel preheater may include a first valve provided in the oxidizer supply line to adjust the flow rate of the oxidizer supplied to the first mixer; a temperature sensor provided in the fuel supply line downstream of the reactor to measure the temperature of the mixed gas; and a control device communicatively connected to the first valve and the temperature sensor, the control device storing a predetermined threshold value associated with the temperature at which a material forming the fuel supply line begins to nitridate, and the control device controlling the first valve to adjust the flow rate of the oxidizer supplied to the first mixer so that the temperature of the mixed gas measured by the temperature sensor is below the threshold value.

[0011] The reactor may include a heating means for heating the catalyst, and the heating means may include a heater.

[0012] Alternatively or additionally, the heating means may include a first heat exchanger for heating the catalyst with exhaust gases from the combustion facility.

[0013] Alternatively or additionally, the heating means may include a second heat exchanger for heating the catalyst with steam extracted from the combustion facility.

[0014] The fuel preheater may include a third mixer that is provided downstream of the reactor in the fuel supply line, the third mixer being connected to a position upstream of the first mixer in the fuel supply line by a second bypass line, and that mixes the mixed gas supplied from the reactor with ammonia supplied from the second bypass line.

[0015] The fuel preheater may include: a second valve provided in the fuel supply line upstream of the first mixer, adjusting the flow rate of ammonia supplied to the first mixer; a temperature sensor provided in the fuel supply line downstream of the reactor, measuring the temperature of the mixed gas; and a control device communicatively connected to the second valve and the temperature sensor, the control device storing a predetermined threshold value associated with a temperature at which a material forming the fuel supply line begins to nitridate, and the control device controlling the second valve to adjust the flow rate of ammonia supplied to the first mixer so that the temperature of the mixed gas measured by the temperature sensor is below the threshold value.

[0016] The fuel preheater may supply the gas mixture to multiple burners of the combustion facility.

[0017] The exothermic reaction in the reactor catalyst may be catalytic combustion.

[0018] Another aspect of the present disclosure is a method for installing a fuel preheater in a combustion facility, the method including: providing a first mixer configured to mix ammonia and an oxidizer; providing a reactor including a catalyst that causes an exothermic reaction with the ammonia; installing the first mixer in a fuel supply line connected to the combustion facility that burns the fuel including the ammonia, wherein the fuel supply line supplies the ammonia to the first mixer; connecting an oxidizer supply line that supplies the oxidizer to the first mixer, wherein the first mixer mixes the ammonia flowing through the fuel supply line with the oxidizer from the oxidizer supply line to generate a mixed gas; and installing a reactor downstream of the first mixer in the fuel supply line, wherein the catalyst causes an exothermic reaction with at least a portion of the ammonia in the mixed gas supplied from the first mixer to heat the mixed gas.

[0019] According to the present disclosure, when ammonia is used as fuel in combustion equipment, the fuel can be supplied to the combustion equipment with an increased combustion rate.

[0020] Fig. 1 is a schematic diagram of a combustion facility including a fuel preheater according to a first embodiment, Fig. 2 is a schematic diagram of a combustion facility including a fuel preheater according to a second embodiment, and Fig. 3 is a schematic diagram of a combustion facility including a fuel preheater according to a third embodiment.

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0022] FIG. 1 is a schematic diagram of a combustion equipment 100 including a fuel preheater 10 according to a first embodiment. The fuel preheater 10 is provided in a fuel supply line L1 connected to the combustion equipment 100. Ammonia-containing gas flows through the fuel supply line L1. For example, the combustion equipment 100 may be a boiler, an industrial furnace, a combustion furnace, or the like. The combustion equipment 100 is not limited to these, and may be various types of equipment that uses ammonia as fuel. The combustion equipment 100 may also be an existing equipment. In another embodiment, the combustion equipment 100 may be a newly constructed equipment. For example, the combustion equipment 100 includes one or more burners B.

[0023] Burner B burns a fuel containing ammonia. For example, burner B may burn a mixture of ammonia and other fuels such as pulverized coal. Burner B may also burn only ammonia. Burner B may also burn a fuel that does not contain ammonia, as needed.

[0024] For example, the fuel preheater 10 includes a first mixer 1, a reactor 2, a second mixer 3, and a control device 90. The fuel preheater 10 may further include other components not shown.

[0025] The first mixer 1 is provided in the fuel supply line L1. For example, the first mixer 1 may be installed in an existing fuel supply line L1 connected to an existing combustion facility 100. For example, the first mixer 1 is a gas mixer. The fuel supply line L1 supplies ammonia to the first mixer 1. For example, the fuel supply line L1 supplies gaseous ammonia to the first mixer 1.

[0026] An oxidant supply line L2 is connected to the first mixer 1. The oxidant supply line L2 supplies an oxidant (for example, air) to the first mixer 1.

[0027] A valve (first valve) V1 is provided in the oxidant supply line L2. The valve V1 is connected to a control device 90 via wire or wireless communication and is controlled by the control device 90. The control device 90 adjusts the flow rate of the oxidant supplied to the first mixer 1 by controlling the opening degree of the valve V1.

[0028] The first mixer 1 mixes ammonia flowing through the fuel supply line L1 with an oxidant supplied from the oxidant supply line L2 to generate a mixed gas containing ammonia and the oxidant. The mixed gas flows through the fuel supply line L1 and is supplied to the reactor 2.

[0029] A nitrogen supply line L3 is connected to the first mixer 1. The nitrogen supply line L3 supplies nitrogen to the first mixer 1.

[0030] A valve V2 is provided in the nitrogen supply line L3. The valve V2 is connected to the control device 90 via wire or wireless communication and is controlled by the control device 90. The control device 90 adjusts the flow rate of nitrogen supplied to the first mixer 1 by controlling the opening degree of the valve V2.

[0031] The reactor 2 is provided downstream of the first mixer 1 in the fuel supply line L1. Like the first mixer 1, the reactor 2 may be installed on an existing fuel supply line L1 connected to an existing combustion facility 100. The reactor 2 receives the mixed gas from the first mixer 1. The reactor 2 includes a catalyst that promotes the reaction of ammonia to cause an exothermic reaction. Specifically, the catalyst promotes the reaction of at least a portion of the ammonia in the mixed gas supplied from the first mixer 1, causing catalytic combustion. The mixed gas is heated by the catalytic combustion. The heated mixed gas flows through the fuel supply line L1 and is supplied to the second mixer 3.

[0032] For example, the catalyst may contain a transition element (which may also be referred to as a transition metal). For example, the catalyst may contain a noble metal such as Ru. Alternatively, for example, the catalyst may contain a non-noble metal such as Fe, Co, or Ni among the transition elements. Non-noble metals may exhibit high activity when combined with a specific support. Examples of the support include Al. ２ O ３ or SiO ２ Oxides such as CeO may also be used as needed. ２ A carrier capable of suppressing sintering such as may be used.

[0033] A temperature sensor S1 is provided in the reactor 2. The temperature sensor S1 is configured to measure the temperature of the catalyst. The temperature sensor S1 is communicably connected to the control device 90 via wire or wirelessly, and transmits measurement data to the control device 90.

[0034] The reactor 2 is provided with a heating means H. The heating means H heats the catalyst. For example, the heating means H may include an electric heater. Alternatively or additionally, the heating means H may include a first heat exchanger that heats the catalyst with exhaust gas from the combustion equipment 100. Further alternatively or additionally, in the case where the combustion equipment 100 includes a boiler, the heating means H may include a second heat exchanger that heats the catalyst with steam extracted from the combustion equipment 100. The heating means H is communicatively connected to the control device 90 via wire or wirelessly and is controlled by the control device 90.

[0035] For example, when the fuel preheater 10 starts operation, the control device 90 starts the operation of the heating means H to heat the catalyst until the temperature measured by the temperature sensor S1 reaches the temperature at which the catalyst begins to activate (e.g., 400°C). When the temperature measured by the temperature sensor S1 reaches the temperature at which the catalyst begins to activate, the control device 90 stops the operation of the heating means H. From this point on, the catalyst is maintained at a sufficient temperature by catalytic combustion.

[0036] The second mixer 3 is provided downstream of the reactor 2 in the fuel supply line L1. Similar to the first mixer 1 and the reactor 2, the second mixer 3 may be installed on an existing fuel supply line L1 connected to an existing combustion facility 100. For example, the second mixer 3 is a gas mixer. The second mixer 3 receives the heated mixed gas from the reactor 2.

[0037] The second mixer 3 is connected to the oxidant supply line L2 by a bypass line (first bypass line) BL1. The bypass line BL1 connects the oxidant supply line L2 directly to the second mixer 3 without passing through the first mixer 1 and the reactor 2. Therefore, at least a portion of the oxidant flowing through the oxidant supply line L2 is supplied to the first mixer 1, and the remainder of the oxidant is supplied to the second mixer 3.

[0038] A valve V3 is provided in the bypass line BL1. The valve V3 is connected to the control device 90 so as to be able to communicate with the control device 90 via wire or wirelessly, and is controlled by the control device 90. The control device 90 adjusts the flow rate of the oxidant supplied to the second mixer 3 by controlling the opening degree of the valve V3.

[0039] The second mixer 3 further mixes the mixed gas flowing through the fuel supply line L1 with an oxidizer supplied from the bypass line BL1. The mixed gas flows through the fuel supply line L1 and is supplied as fuel to the burner B (premixed combustion system). In another embodiment, the burner B may be of a diffusion combustion system.

[0040] A temperature sensor S2 is provided in the fuel supply line L1 at a position downstream of the reactor 2, specifically, in this embodiment, at a position downstream of the second mixer 3. The temperature sensor S2 is configured to measure the temperature of the mixed gas flowing through the fuel supply line L1. The temperature sensor S2 is connected to the control device 90 so as to be able to communicate with the control device 90 via wire or wirelessly, and transmits measurement data to the control device 90.

[0041] The fuel supply line L1 branches into a plurality of lines at a position downstream of the temperature sensor S2 and is connected to each of the plurality of burners B.

[0042] The control device 90 controls the fuel preheater 10. The control device 90 may also control at least some of the components of the combustion equipment 100. For example, the combustion equipment 100 may include a main control device (not shown), and the control device 90 may communicate with the main control device. The control device 90 includes components such as a processor 90a, a storage device 90b, and a connector 90c, which are connected to each other via a bus. For example, the processor 90a includes a central processing unit (CPU). For example, the storage device 90b includes a hard disk, a ROM for storing programs, and a RAM as a work area. The control device 90 is connected to each component of the fuel preheater 10 via the connector 90c so as to be able to communicate with them via a wired or wireless connection. For example, the control device 90 may further include other components, such as a display device such as a liquid crystal display or a touch panel, and an input device such as a keyboard, buttons, or a touch panel. For example, the operation of the control device 90 may be realized by the processor 90a executing a program stored in the storage device 90b.

[0043] The catalyst in reactor 2 promotes the reaction of ammonia, resulting in the following reactions (1), (2), or a combination thereof: (1) NH ３ →1.5H ２ +0.5N ２ ΔH=45.4 (kJ / mol) (2) 2NH ３ +1.5O ２ →N ２ +3H ２ O ΔH = -382.6 (kJ / mol)

[0044] For example, in this embodiment, the catalyst can cause both reactions (1) and (2). For example, the control device 90 may control the valve V1 to adjust the amount of oxidant allocated from the oxidant supply line L2 to the first mixer 1, i.e., the amount of oxidant supplied to the reactor 2, so that most of the oxidant in the mixed gas supplied to the reactor 2 is used by the exothermic reaction (2). The control device 90 may also control the valve V3 as necessary.

[0045] For example, if reactor 2 requires more oxidant for catalytic combustion, controller 90 increases the flow rate of the oxidant supplied from oxidant supply line L2 to reactor 2. In contrast, for example, if the amount of oxidant supplied to reactor 2 is excessive, controller 90 reduces the flow rate of the oxidant supplied from oxidant supply line L2 to reactor 2.

[0046] The oxidizer required for combustion in the burner B is supplied from the oxidizer supply line L2 through the bypass line BL1 to the second mixer 3, where it is mixed with the heated mixed gas. The control device 90 controls the valve V3 to adjust the amount of oxidizer allocated from the oxidizer supply line L2 to the bypass line BL1, i.e., the amount of oxidizer supplied to the second mixer 3. The control device 90 may also control the valve V1 as necessary.

[0047] For example, if burner B requires more oxidizer for combustion, the control device 90 may increase the flow rate of the oxidizer supplied from the oxidizer supply line L2 to the second mixer 3. In contrast, for example, if the amount of oxidizer supplied to burner B is excessive, the control device 90 may reduce the flow rate of the oxidizer supplied from the oxidizer supply line L2 to the second mixer 3.

[0048] The control device 90 also stores a predetermined threshold value in the storage device 90b. This threshold value is associated with the temperature at which the material forming the fuel supply line L1 begins to nitride. For example, the fuel supply line L1 may be formed of steel such as stainless steel. It is known that many steels are nitrided when exposed to an environment containing ammonia at temperatures of approximately 400°C to 600°C. Therefore, most steels will not nitride even when exposed to an environment containing ammonia at temperatures below the above range. Specifically, the threshold value may be 400°C, for example.

[0049] The threshold value may also be determined by testing. For example, a test piece made of the same material as that forming the fuel supply line L1 is placed in an environment simulating the interior of the fuel supply line L1. The environment is maintained for a predetermined period of time (e.g., one month, several months, one year, or several years). The nitride layer depth of the test piece is then measured, and the annual nitriding rate (mm / year) is calculated. This test is performed at a plurality of temperatures. For example, the temperature at which the nitriding rate is less than a predetermined value may be determined as the threshold value (e.g., less than 1 mm / year). For example, the nitride layer depth may be measured by the "measurement method by hardness test" or the "measurement method by metallographic test" in the "method for measuring nitride layer depth of steel" defined in JIS G0562.

[0050] The control device 90 may control at least one of the valves V1 and V3 to adjust the flow rate of the oxidant supplied to the reactor 2 and the flow rate of the oxidant supplied to the second mixer 3 so that the temperature of the mixed gas measured by the temperature sensor S2 is below a threshold value.

[0051] In addition, if the temperature of the mixed gas measured by temperature sensor S2 is excessively high, i.e., if the catalyst is excessively heated due to an exothermic reaction, control device 90 may open valve V2 and add nitrogen to the mixed gas as an emergency coolant.

[0052] The fuel supply line L1 may be provided with a valve (not shown) for adjusting the flow rate of ammonia supplied to the first mixer 1. Each of the lines L1, L2, and L3 may be provided with a pump (not shown) for sending a fluid. These valves and pumps may be connected to the control device 90 so as to be able to communicate with it via wire or wirelessly, and may be controlled by the control device 90.

[0053] Next, the operation of the fuel preheater 10 will be described.

[0054] When the fuel preheater 10 starts operation, the control device 90 starts the operation of the heating means H. The catalyst is heated until the temperature measured by the temperature sensor S1 reaches a temperature at which the catalyst starts to become active.

[0055] When the temperature measured by the temperature sensor reaches a temperature at which the catalyst begins to activate, the control device 90 controls the valve V1 to start supplying the oxidizer to the first mixer 1. The first mixer 1 also receives ammonia from the fuel supply line L1. The first mixer 1 mixes the ammonia and the oxidizer to generate a mixed gas. The mixed gas is supplied to the reactor 2 via the fuel supply line L1.

[0056] The control device 90 also stops the operation of the heating means H. After this, the catalyst is maintained at a sufficient temperature by catalytic combustion.

[0057] At least a portion of the oxidant in the mixed gas, for example, most of the oxidant in the mixed gas, reacts with ammonia on the catalyst in the reactor 2, causing catalytic combustion. This heats the mixed gas. The heated mixed gas is supplied to the second mixer 3 through the fuel supply line L1.

[0058] The control device 90 controls the valve V3 to start supplying the oxidizer required for combustion in the burner B to the second mixer 3. The second mixer 3 also receives the heated mixed gas from the fuel supply line L1. The second mixer 3 further mixes the ammonia and the oxidizer. The heated mixed gas is supplied to the multiple burners B via the fuel supply line L1 as premixed fuel.

[0059] The fuel preheater 10 described above includes a first mixer 1 provided in a fuel supply line L1 connected to a combustion facility 100 that combusts a fuel containing ammonia, and a reactor 2 provided downstream of the first mixer 1 on the fuel supply line L1. The fuel supply line L1 supplies ammonia to the first mixer 1. The first mixer 1 is connected to an oxidizer supply line L2 that supplies an oxidizer, and mixes the ammonia flowing through the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to generate a mixed gas. The reactor 2 includes a catalyst that promotes the reaction of ammonia to cause an exothermic reaction. The catalyst causes an exothermic reaction with at least a portion of the ammonia in the mixed gas supplied from the first mixer 1, thereby heating the mixed gas. With this configuration, a mixed gas containing ammonia and heated by the exothermic reaction in the reactor 2 can be supplied to the combustion facility 100. Because the mixed gas is heated by the exothermic reaction, the ammonia in the mixed gas is also heated, increasing the combustion rate of the ammonia. Therefore, fuel can be supplied to the combustion facility 100 with an increased combustion rate.

[0060] The fuel preheater 10 also includes a second mixer 3 provided downstream of the reactor 2 in the fuel supply line L1. The second mixer 3 is connected to the oxidant supply line L2 via a bypass line BL1, and mixes the mixed gas supplied from the reactor 2 with the oxidant supplied from the bypass line BL1. With this configuration, the amount of oxidant supplied from the oxidant supply line L2 to the reactor 2 can be adjusted more precisely.

[0061] The fuel preheater 10 also includes a valve V1 provided in the oxidizer supply line L2 to adjust the flow rate of the oxidizer, a temperature sensor S2 provided in the fuel supply line L1 downstream of the reactor 2 to measure the temperature of the mixed gas, and a control device 90 communicatively connected to the valve V1 and the temperature sensor S2. The control device 90 stores a predetermined threshold value associated with the temperature at which nitriding of the material forming the fuel supply line L1 begins. The control device 90 controls the valve V1 to adjust the flow rate of the oxidizer supplied to the first mixer 1 so that the temperature of the mixed gas measured by the temperature sensor S2 is below the threshold value. This configuration makes it possible to suppress embrittlement of the fuel supply line L1 due to nitriding.

[0062] The reactor 2 further includes a heating means H for heating the catalyst, and the heating means H may include a heater. With this configuration, the catalyst can be quickly heated to a temperature at which the catalyst starts to become active.

[0063] Alternatively or additionally, the heating means H may include a first heat exchanger that heats the catalyst with exhaust gas from the combustion equipment 100. With such a configuration, the catalyst can be quickly heated to a temperature at which the catalyst begins to become active, and the exhaust gas can be reused.

[0064] Alternatively or additionally, the heating means H may include a second heat exchanger that heats the catalyst with steam extracted from the combustion equipment 100. With such a configuration, the catalyst can be quickly heated to a temperature at which the catalyst begins to become active.

[0065] Furthermore, the fuel preheater 10 supplies the mixed gas to a plurality of burners B of the combustion equipment 100. With this configuration, it is not necessary to provide a fuel preheater for each burner B.

[0066] Furthermore, the exothermic reaction in the catalyst of reactor 2 is catalytic combustion. With this configuration, flameless combustion, mainly involving a surface reaction, is carried out in reactor 2, resulting in a high level of safety. Furthermore, by changing the flow rate of the oxidizer, the air ratio in reactor 2 can be changed, thereby controlling the temperature of the mixed gas. By increasing the temperature of the mixed gas, the ignition ability and combustion stability of the flame-retardant ammonia in burner B can be improved.

[0067] Furthermore, the fuel preheater 10 as described above can be installed in an existing combustion equipment 100. A method for installing the fuel preheater 10 in the combustion equipment 100 according to this embodiment includes: preparing a first mixer 1 configured to mix ammonia and an oxidizer; preparing a reactor 2 including a catalyst that causes an exothermic reaction with ammonia; and installing the first mixer 1 in a fuel supply line L1 connected to the combustion equipment 100 that burns a fuel containing ammonia. Thus, the fuel supply line L1 supplies ammonia to the first mixer 1. The method according to this embodiment also includes connecting an oxidizer supply line L2 that supplies an oxidizer to the first mixer 1. Thus, the first mixer 1 mixes the ammonia flowing through the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to generate a mixed gas. The method according to this embodiment also includes installing the reactor 2 downstream of the first mixer 1 in the fuel supply line L1. Thus, the catalyst causes an exothermic reaction with at least a portion of the ammonia in the mixed gas supplied from the first mixer 1, heating the mixed gas. With this configuration, fuel can be supplied to the existing combustion facility 100 at an increased combustion rate without requiring major construction work.

[0068] 1 and the following Figures 2 and 3, fuel preheaters 10, 10A, and 10B include components surrounded by dashed lines. Therefore, a method of installing fuel preheater 10, 10A, or 10B in combustion equipment 100 according to the present disclosure may further include installing components other than first mixer 1 and reactor 2 within the dashed lines to an existing fuel supply line L1.

[0069] Next, other embodiments will be described.

[0070] 2 is a schematic diagram of a combustion facility 100 including a fuel preheater 10A according to the second embodiment. The fuel preheater 10A differs from the fuel preheater 10 according to the first embodiment in that it includes an ammonia bypass line (second bypass line) BL2 and a third mixer 4 instead of the oxidant bypass line BL1 and the second mixer 3. The other configurations of the fuel preheater 10A may be the same as those of the fuel preheater 10.

[0071] The third mixer 4 is provided downstream of the reactor 2 in the fuel supply line L1. The third mixer 4 may be installed on the existing fuel supply line L1 connected to the existing combustion equipment 100. For example, the third mixer 4 is a gas mixer. The third mixer 4 receives the heated mixed gas from the reactor 2.

[0072] The third mixer 4 is connected by a bypass line BL2 to a position in the fuel supply line L1 upstream of the first mixer 1. The bypass line BL2 connects the fuel supply line L1 directly to the third mixer 4 without passing through the first mixer 1 and the reactor 2. Therefore, at least a portion of the ammonia flowing through the fuel supply line L1 is supplied to the first mixer 1, and the remainder of the ammonia is supplied to the third mixer 4.

[0073] In this embodiment, a valve (second valve) V4 is provided in the fuel supply line L1 between the connecting portion to the bypass line BL2 and the first mixer 1. The valve V4 is connected to the control device 90 so as to be able to communicate with the control device 90 via wire or wirelessly, and is controlled by the control device 90. The control device 90 adjusts the flow rate of ammonia supplied to the first mixer 1 by controlling the opening degree of the valve V4.

[0074] A valve V5 is provided in the bypass line BL2. The valve V5 is communicably connected to the control device 90 via wire or wirelessly and is controlled by the control device 90. The control device 90 adjusts the flow rate of ammonia supplied to the third mixer 4 by controlling the opening degree of the valve V5.

[0075] The third mixer 4 further mixes the mixed gas flowing through the fuel supply line L1 with ammonia supplied from the bypass line BL2. The mixed gas flows through the fuel supply line L1 and is supplied to the burner B as fuel.

[0076] For example, the control device 90 may control the valve V4 to adjust the flow rate of ammonia allocated from the fuel supply line L1 to the first mixer 1, i.e., the flow rate of ammonia supplied to the reactor 2, so that most of the ammonia in the mixed gas supplied to the reactor 2 is used by the exothermic reaction (2). The control device 90 may also control the valve V5 as necessary.

[0077] For example, if reactor 2 needs to heat the mixed gas more, controller 90 may increase the flow rate of ammonia supplied from fuel supply line L1 to reactor 2. In contrast, for example, if reactor 2 is overheating the mixed gas, controller 90 may decrease the flow rate of oxidant supplied from fuel supply line L1 to reactor 2.

[0078] Ammonia required for combustion in the burner B is supplied from the fuel supply line L1 through the bypass line BL2 to the third mixer 4, and is mixed with the heated mixed gas in the third mixer 4. The control device 90 controls the valve V5 to adjust the amount of ammonia allocated from the fuel supply line L1 to the bypass line BL2, i.e., the amount of ammonia supplied to the third mixer 4. The control device 90 may also control the valve V4 as necessary.

[0079] For example, if burner B requires more ammonia for combustion, the control device 90 may increase the flow rate of ammonia supplied from the fuel supply line L1 to the third mixer 4. In contrast, for example, if the amount of ammonia supplied to burner B is excessive, the control device 90 may reduce the flow rate of ammonia supplied from the fuel supply line L1 to the third mixer 4.

[0080] Furthermore, similarly to the first embodiment, the control device 90 may adjust the flow rate of ammonia supplied to the reactor 2 and the flow rate of ammonia supplied to the third mixer 4 by controlling at least one of the valves V4 and V5 so that the temperature of the mixed gas measured by the temperature sensor S2 becomes less than a threshold value (for example, 400°C).

[0081] The fuel preheater 10A described above achieves substantially the same effects as the fuel preheater 10 according to the first embodiment. The fuel preheater 10A also includes a third mixer 4 provided downstream of the reactor 2 in the fuel supply line L1. The third mixer 4 is connected to the fuel supply line L1 at a position upstream of the first mixer 1 via a bypass line BL2, and mixes the mixed gas supplied from the reactor 2 with ammonia supplied from the bypass line BL2. This configuration allows for more precise adjustment of the amount of ammonia supplied from the fuel supply line L1 to the reactor 2.

[0082] The fuel preheater 10A also includes a valve V4 located upstream of the first mixer 1 in the fuel supply line L1 and regulating the flow rate of ammonia supplied to the first mixer 1, a temperature sensor S2 located downstream of the reactor 2 in the fuel supply line L1 and measuring the temperature of the mixed gas, and a control device 90 communicatively connected to the valve V4 and the temperature sensor S2. The control device 90 stores a predetermined threshold value associated with the temperature at which nitriding of the material forming the fuel supply line L1 begins. The control device 90 controls the valve V4 to regulate the flow rate of ammonia supplied to the first mixer 1 so that the temperature of the mixed gas measured by the temperature sensor S2 is below the threshold value. This configuration can suppress embrittlement of the fuel supply line L1 due to nitriding.

[0083] 3 is a schematic diagram of a combustion facility 100 including a fuel preheater 10B according to a third embodiment. The fuel preheater 10B differs from the fuel preheater 10 according to the first embodiment in that it does not include a bypass line BL1 and a second mixer 3. The other configurations of the fuel preheater 10B may be the same as those of the fuel preheater 10.

[0084] In this embodiment, each burner B of the combustion equipment 100 is of a diffusion combustion type. Air necessary for diffusion combustion is supplied to each burner B. The combustion equipment 100 may include components (not shown), such as an air register and a damper, for adjusting the amount of air supplied to each burner B. Note that air is shown only for the top burner B in FIG. 3 .

[0085] For example, the control device 90 controls the valve V1 to adjust the amount of oxidant supplied from the oxidant supply line L2 to the reactor 2 via the first mixer 1 so that most of the oxidant in the mixed gas supplied to the reactor 2 is used by the exothermic reaction (2).

[0086] Furthermore, as in the first embodiment, the control device 90 controls the valve V1 to adjust the flow rate of the oxidant supplied to the reactor 2 so that the temperature of the mixed gas measured by the temperature sensor S2 is less than a threshold value (e.g., 400°C).

[0087] The fuel preheater 10B as described above provides substantially the same effects as the fuel preheater 10 according to the first embodiment.

[0088] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also fall within the technical scope of the present disclosure. Furthermore, the steps of the method of the above embodiments do not have to be performed in the order described above, and may be performed in a different order as long as no technical contradiction occurs.

[0089] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0090] REFERENCE SIGNS LIST 1 First mixer 2 Reactor 3 Second mixer 4 Third mixer 10 Fuel preheater 10A Fuel preheater 10B Fuel preheater 90 Control device 100 Combustion equipment B Burner BL1 Bypass line (first bypass line) BL2 Bypass line (second bypass line) H Heating means L1 Fuel supply line L2 Oxidizer supply line L3 Nitrogen supply line S1 Temperature sensor S2 Temperature sensor V1 Valve (first valve) V4 Valve (second valve)

Claims

1. A fuel preheater comprising: a first mixer provided in a fuel supply line connected to a combustion facility that combusts a fuel containing ammonia, the fuel supply line supplying ammonia to the first mixer, the first mixer being connected to an oxidizer supply line that supplies an oxidizer, and mixing the ammonia flowing through the fuel supply line with the oxidizer from the oxidizer supply line to generate a mixed gas; and a reactor provided in the fuel supply line downstream of the first mixer, the reactor including a catalyst that promotes a reaction of ammonia to cause an exothermic reaction, the catalyst causing the exothermic reaction by at least a portion of the ammonia in the mixed gas supplied from the first mixer, and heating the mixed gas.

2. A fuel preheater as described in claim 1, comprising a second mixer provided downstream of the reactor in the fuel supply line, the second mixer being connected to the oxidizer supply line by a first bypass line, and mixing the mixed gas supplied from the reactor with the oxidizer supplied from the first bypass line.

3. The fuel preheater according to claim 1 or 2, comprising: a first valve provided in the oxidizer supply line and adjusting the flow rate of the oxidizer supplied to the first mixer; a temperature sensor provided in the fuel supply line downstream of the reactor and measuring the temperature of the mixed gas; and a control device communicatively connected to the first valve and the temperature sensor, the control device storing a predetermined threshold value associated with a temperature at which a material forming the fuel supply line begins to be nitriding, and the control device controlling the first valve to adjust the flow rate of the oxidizer supplied to the first mixer such that the temperature of the mixed gas measured by the temperature sensor is less than the threshold value.

4. The fuel preheater of claim 1, wherein said reactor includes a heating means for heating said catalyst, said heating means including a heater.

5. A fuel preheater as described in claim 1, wherein the reactor includes a heating means for heating the catalyst, the heating means including a first heat exchanger for heating the catalyst with exhaust gas from the combustion facility.

6. A fuel preheater as described in claim 1, wherein the reactor includes a heating means for heating the catalyst, the heating means including a second heat exchanger for heating the catalyst with steam extracted from the combustion facility.

7. The fuel preheater according to claim 1, further comprising a third mixer provided downstream of the reactor in the fuel supply line, the third mixer being connected by a second bypass line to a position upstream of the first mixer in the fuel supply line, and mixing the mixed gas supplied from the reactor with ammonia supplied from the second bypass line.

8. The fuel preheater according to claim 1 or 7, comprising: a second valve provided in the fuel supply line upstream of the first mixer, adjusting a flow rate of ammonia supplied to the first mixer; a temperature sensor provided in the fuel supply line downstream of the reactor, measuring a temperature of the mixed gas; and a control device communicatively connected to the second valve and the temperature sensor, the control device storing a predetermined threshold value associated with a temperature at which a material forming the fuel supply line starts to be nitriding, and the control device controlling the second valve to adjust the flow rate of ammonia supplied to the first mixer such that the temperature of the mixed gas measured by the temperature sensor is less than the threshold value.

9. The fuel preheater of claim 1, wherein the fuel preheater supplies the mixed gas to a plurality of burners of the combustion facility.

10. The fuel preheater of claim 1, wherein the exothermic reaction in the catalyst of the reactor is catalytic combustion.

11. A method for installing a fuel preheater in a combustion facility, comprising: preparing a first mixer configured to mix ammonia and an oxidizer; preparing a reactor including a catalyst that induces an exothermic reaction with ammonia; installing the first mixer in a fuel supply line connected to a combustion facility that burns a fuel including ammonia, the fuel supply line supplying ammonia to the first mixer; connecting an oxidizer supply line that supplies an oxidizer to the first mixer, the first mixer mixing the ammonia flowing through the fuel supply line with the oxidizer from the oxidizer supply line to generate a mixed gas; and installing the reactor downstream of the first mixer in the fuel supply line, the catalyst inducing the exothermic reaction with at least a portion of the ammonia in the mixed gas supplied from the first mixer, and heating the mixed gas.