Fuel preheater

Abstract

A fuel preheater (10) is provided with: a first mixer (1) provided in a fuel supply line (L1) connected to a combustion facility (100) for combusting an ammonia-containing fuel, 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 supplying an oxidizing agent, and the oxidizing agent supply line (L2) being connected to the combustion facility (100) for combusting the ammonia-containing fuel; mixing the ammonia flowing in the fuel supply line (L1) with the oxidant from the oxidant supply line (L2) to generate a mixed gas; and a reactor (2) provided downstream of the first mixer (1) in the fuel supply line (L1), the reactor (2) containing a catalyst that promotes the reaction of ammonia and causes 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 (1), and heating the mixed gas.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a fuel preheater. This application claims the benefit of priority of Japanese Patent Application No. 2023-097818 filed on June 14, 2023, the contents of which are incorporated herein. BACKGROUND

[0002] In combustion equipment, a catalyst is sometimes used in order to promote combustion. For example, Patent Literature 1 discloses a catalytic flameless combustion device. In this device, a mixed gas of air and natural gas is combusted on a catalyst filled in a combustion chamber.

[0003] In addition, Patent Literature 2 discloses a catalytic combustor. In this combustor, a mixed gas of a gaseous fuel such as natural gas or city gas and air is combusted on a catalyst.

[0004] In addition, Patent Literature 3 discloses a combustor portion of a gas turbine. In this gas turbine, a mixed gas of natural gas and air is oxidized by a catalyst, and then combusted by a pilot flame and a main flame.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2019-511696

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2019-529847

[0009] Patent Literature 3: Japanese Patent Application Publication No. H11-509307 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] Ammonia is known as a fuel that does not release CO2. However, the combustion speed of ammonia is slower than that of other fuels such as natural gas. Therefore, in the case where ammonia is used in combustion equipment, it is preferable to increase the combustion speed of ammonia.

[0012] An object of the present disclosure is to provide a fuel preheater that is capable of supplying a fuel to combustion equipment in a state where the combustion speed is increased, in the case where ammonia is used as a fuel in the combustion equipment. In addition, an object of the present disclosure is to provide a method for arranging such a fuel preheater in combustion equipment.

[0013] MEANS FOR SOLVING THE PROBLEMS

[0014] A fuel preheater according to an embodiment of the present invention includes a first mixer provided in a fuel supply line connected to a combustion device 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 and 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 containing a catalyst that promotes a reaction of the 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.

[0015] The fuel preheater can include a second mixer provided in the fuel supply line downstream of the reactor, the second mixer being connected to the oxidizer supply line through a first bypass line and mixing the mixed gas supplied from the reactor and the oxidizer supplied from the first bypass line.

[0016] The fuel preheater can include a first valve provided in the oxidizer supply line, the first valve adjusting a flow rate of the oxidizer supplied to the first mixer; a temperature sensor provided in the fuel supply line downstream of the reactor, the temperature sensor measuring a 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 starts nitriding, 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 less than the threshold value.

[0017] The reactor can include a heating unit for heating the catalyst, and the heating unit can include a heater.

[0018] Alternatively or additionally, the heating unit can include a first heat exchanger that heats the catalyst using exhaust gas from the combustion device.

[0019] Alternatively or additionally, the heating unit can include a second heat exchanger that heats the catalyst using steam extracted from the combustion device.

[0020] The fuel preheater can include a third mixer provided in the fuel supply line downstream of the reactor, the third mixer being connected to the fuel supply line at a position upstream of the first mixer through a second bypass line and mixing the mixed gas supplied from the reactor and the ammonia supplied from the second bypass line.

[0021] The fuel preheater can include a second valve disposed in the fuel supply line upstream of the first mixer, adjusting the flow rate of ammonia supplied to the first mixer; a temperature sensor disposed 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 the temperature at which the material forming the fuel supply line begins nitriding, 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 less than the threshold value.

[0022] The fuel preheater can supply the mixed gas to a plurality of burners of the combustion device.

[0023] The exothermic reaction in the catalyst of the reactor can be catalytic combustion.

[0024] Another aspect of the present disclosure is a method of installing a fuel preheater to a combustion device, the method including: preparing a first mixer configured to mix ammonia and an oxidizing agent; preparing a reactor including a catalyst that causes an ammonia-based exothermic reaction; disposing the first mixer in a fuel supply line connected to a combustion device that combusts a fuel containing ammonia, the fuel supply line supplying ammonia to the first mixer; connecting an oxidizing agent supply line that supplies an oxidizing agent to the first mixer, the first mixer mixing the ammonia flowing through the fuel supply line and the oxidizing agent from the oxidizing agent supply line to generate a mixed gas; and disposing the reactor downstream of the first mixer in the fuel supply line, the catalyst causing the exothermic reaction by at least a portion of the ammonia in the mixed gas supplied from the first mixer, the mixed gas being heated.

[0025] Effects of the Invention

[0026] According to the present disclosure, in the case where ammonia is used as a fuel in a combustion device, the fuel can be supplied to the combustion device at a state where the combustion speed is improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a schematic view of a combustion device equipped with the fuel preheater of the first embodiment.

[0028] Figure 2 is a schematic view of a combustion device equipped with the fuel preheater of the second embodiment.

[0029] Figure 3 is a schematic view of a combustion device equipped with the fuel preheater of the third embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The specific dimensions, materials, and numerical values and the like shown in the embodiment are merely examples for easy understanding, and do not limit the present disclosure unless otherwise specified. Furthermore, in the present specification and the drawings, elements having substantially the same function, structure, and the like are denoted by the same reference numerals, and repeated explanation is omitted, and elements having no direct relation to the present disclosure are omitted from the illustration.

[0031] Figure 1 is a schematic view of a combustion device 100 provided with the fuel preheater 10 of the first embodiment. The fuel preheater 10 is provided in a fuel supply line L1 connected to the combustion device 100. An ammonia-containing gas flows in the fuel supply line L1. The combustion device 100 can be, for example, a boiler, an industrial furnace, or a combustion furnace, and the like. The combustion device 100 is not limited thereto, and can be various devices that use ammonia as a fuel. In addition, the combustion device 100 can also be an existing device. In other embodiments, the combustion device 100 can also be a newly installed device. For example, the combustion device 100 includes one or more burners B.

[0032] The burner B causes the ammonia-containing fuel to burn. For example, the burner B can also cause a mixed fuel of ammonia and other fuel such as pulverized coal to burn. In addition, the burner B can also cause only ammonia to burn. In addition, the burner B can also cause a fuel not containing ammonia to burn as needed.

[0033] 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 can also include other constituent elements not illustrated.

[0034] The first mixer 1 is provided in the fuel supply line L1. For example, the first mixer 1 can also be provided in an existing fuel supply line L1 connected to an existing combustion device 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.

[0035] An oxidizing agent supply line L2 is connected to the first mixer 1. The oxidizing agent supply line L2 supplies an oxidizing agent (for example, air) to the first mixer 1.

[0036] A valve (first valve) V1 is provided in the oxidizing agent supply line L2. The valve V1 is communicably connected to the control device 90 in a wired or wireless manner, and is controlled by the control device 90. The control device 90 adjusts the flow rate of the oxidizing agent supplied to the first mixer 1 by controlling the opening degree of the valve V1.

[0037] The first mixer 1 mixes ammonia flowing in the fuel supply line Ll with an oxidizing agent supplied from the oxidizing agent supply line L2, to generate a mixed gas containing ammonia and the oxidizing agent. The mixed gas flows in the fuel supply line Ll, and is supplied to the reactor 2.

[0038] The first mixer 1 is connected to a nitrogen supply line L3. The nitrogen supply line L3 supplies nitrogen to the first mixer 1.

[0039] A valve V2 is provided in the nitrogen supply line L3. The valve V2 is communicably connected to the control device 90 in a wired or wireless manner, and is controlled by the control device 90. The control device 90 adjusts the flow rate of the nitrogen supplied to the first mixer 1 by controlling the opening degree of the valve V2.

[0040] The reactor 2 is provided in the fuel supply line Ll downstream of the first mixer 1. As with the first mixer 1, the reactor 2 can also be provided in the existing fuel supply line Ll connected to the existing combustion device 100. The reactor 2 receives the mixed gas from the first mixer 1. The reactor 2 contains a catalyst that promotes the reaction of ammonia to cause an exothermic reaction. Specifically, the catalyst promotes the reaction of at least a part of the ammonia in the mixed gas supplied from the first mixer 1, to cause catalytic combustion. The mixed gas is heated by the catalytic combustion. The heated mixed gas flows in the fuel supply line Ll, and is supplied to the second mixer 3.

[0041] For example, the catalyst contains a transition element (may also be referred to as a transition metal). For example, the catalyst can also contain a noble metal such as Ru. In addition, for example, the catalyst can contain a non-noble metal such as Fe, Co, Ni, or the like among the transition elements. The non-noble metal sometimes exhibits high activity in combination with a specific carrier. As the carrier, for example, an oxide such as Al2O3 or SiO2 can be used. In addition, as needed, a carrier capable of suppressing sintering such as CeO2 can also be used.

[0042] 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 in a wired or wireless manner, and transmits the measurement data to the control device 90.

[0043] A heating unit H is provided in the reactor 2. The heating unit H heats the catalyst. For example, the heating unit H can also include an electric heater. Alternatively or additionally, the heating unit H can also include a first heat exchanger that heats the catalyst using exhaust gas from the combustion device 100. Furthermore, alternatively or additionally, in the case where the combustion device 100 includes a boiler, the heating unit H can also include a second heat exchanger that heats the catalyst using steam drawn from the combustion device 100. The heating unit H is communicably connected to the control device 90 in a wired or wireless manner, and is controlled by the control device 90.

[0044] For example, when the fuel preheater 10 starts operation, the control device 90 starts the operation of the heating unit H to heat the catalyst until the temperature measured by the temperature sensor S1 reaches a temperature at which the catalyst starts to activate (for example, 400°C). When the temperature measured by the temperature sensor S1 reaches the temperature at which the catalyst starts to activate, the control device 90 stops the operation of the heating unit H. Thereafter, the catalyst is maintained at a sufficient temperature by catalytic combustion.

[0045] The second mixer 3 is provided downstream of the reactor 2 in the fuel supply line L1. As with the first mixer 1 and the reactor 2, the second mixer 3 can also be provided in the existing fuel supply line L1 connected to the 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.

[0046] The second mixer 3 is connected to the oxidizer supply line L2 by a bypass line (first bypass line) BL1. The bypass line BL1 connects the oxidizer supply line L2 directly to the second mixer 3 without passing through the first mixer 1 and the reactor 2. Therefore, at least a part of the oxidizer flowing in the oxidizer supply line L2 is supplied to the first mixer 1, and the remaining part of the oxidizer is supplied to the second mixer 3.

[0047] A valve V3 is provided in the bypass line BL1. The valve V3 is communicably connected to the control device 90 in a wired or wireless manner and is controlled by the control device 90. The control device 90 adjusts the flow rate of the oxidizer supplied to the second mixer 3 by controlling the opening degree of the valve V3.

[0048] The second mixer 3 further mixes the mixed gas flowing in the fuel supply line L1 with the oxidizer supplied from the bypass line BL1. The mixed gas flows in the fuel supply line L1 and is supplied as fuel to the combustor B (premixed combustion system). In other embodiments, the combustor B can also be a diffusion combustion system.

[0049] A temperature sensor S2 is provided in the fuel supply line L1 at a position downstream of the reactor 2, specifically at a position downstream of the second mixer 3 in the present embodiment. The temperature sensor S2 is configured to measure the temperature of the mixed gas flowing in the fuel supply line L1. The temperature sensor S2 is communicably connected to the control device 90 in a wired or wireless manner and transmits the measurement data to the control device 90.

[0050] The fuel supply line L1 branches into a plurality of lines at a position downstream of the temperature sensor S2 and is connected to the plurality of combustors B, respectively.

[0051] The control device 90 controls the fuel preheater 10. In addition, the control device 90 can also control at least a part of the constituent elements of the combustion device 100. In addition, for example, the combustion device 100 can be provided with a main control device not shown, and the control device 90 can communicate with the main control device. The control device 90 includes, for example, a processor 90a, a storage device 90b, a connector 90c, and the like, which are connected to each other via a bus. The processor 90a includes, for example, a CPU (Central Processing Unit) or the like. The storage device 90b includes, for example, a hard disk, a ROM storing a program, and a RAM serving as a work area, or the like. The control device 90 is communicably connected to the constituent elements of the fuel preheater 10 via the connector 90c in a wired or wireless manner. The control device 90 can further include, for example, a display device such as a liquid crystal display or a touch panel, an input device such as a keyboard, a button, or a touch panel, and other constituent elements. The operation of the control device 90 can be realized, for example, by causing the processor 90a to execute a program stored in the storage device 90b.

[0052] The catalyst in the reactor 2 promotes the reaction of ammonia, causing the following reactions (1), (2), or a combination thereof.

[0053] (1) NH3→ 1.5H2+ 0.5N2 ΔH = 45.4 (kJ / mol)

[0054] (2) 2NH3+ 1.5O2→ N2+ 3H2O ΔH = -382.6 (kJ / mol)

[0055] For example, in the present embodiment, the catalyst can cause both reactions (1) and (2). For example, the control device 90 can control the valve V1, adjust the amount of oxidant distributed from the oxidant supply line L2 to the first mixer 1, that is, the amount of oxidant supplied to the reactor 2, in such a manner that a large part of the oxidant in the mixed gas supplied to the reactor 2 is used as reaction (2) which is an exothermic reaction. In addition, the control device 90 can control the valve V3 as needed.

[0056] For example, in the case where the reactor 2 requires more oxidant for catalytic combustion, the control device 90 increases the flow rate of the oxidant supplied from the oxidant supply line L2 to the reactor 2. In contrast, for example, in the case where the amount of oxidant supplied to the reactor 2 is excessive, the control device 90 reduces the flow rate of the oxidant supplied from the oxidant supply line L2 to the reactor 2.

[0057] The oxidizer required for combustion in the combustor B is supplied from the oxidizer supply line L2 to the second mixer 3 via the bypass line BLl, and mixed with the heated mixed gas in the second mixer 3. The control device 90 controls the valve V3 to adjust the amount of oxidizer distributed from the oxidizer supply line L2 to the bypass line BLl, that is, the amount of oxidizer supplied to the second mixer 3. In addition, the control device 90 can also control the valve VI as needed.

[0058] For example, in the case where the combustor B requires more oxidizer for combustion, the control device 90 can also increase the flow rate of oxidizer supplied from the oxidizer supply line L2 to the second mixer 3. In contrast, for example, in the case where the amount of oxidizer supplied to the combustor B is excessive, the control device 90 can also decrease the flow rate of oxidizer supplied from the oxidizer supply line L2 to the second mixer 3.

[0059] In addition, the control device 90 stores a predetermined threshold value in the storage device 90b. The threshold value is associated with the temperature at which the material forming the fuel supply line Ll begins to nitride. For example, the fuel supply line Ll can also be formed of steel such as stainless steel. It is known that many steels nitride when exposed to an environment containing ammonia at approximately 400°C to 600°C. Therefore, most steels do not nitride even when exposed to an environment containing ammonia as long as the temperature is below the above range. Specifically, for example, the threshold value can be 400°C.

[0060] In addition, the threshold value can also be determined by experiment. For example, a test piece formed of the same material as the material forming the fuel supply line Ll is disposed in an environment simulating the inside of the fuel supply line Ll. The environment is maintained for a predetermined period (for example, one month, a plurality of months, one year, or a plurality of years). Then, the depth of the nitrided layer of the test piece is measured, and the nitriding speed per one year (mm / year) is calculated. The experiment is performed at a plurality of temperatures. For example, the temperature at which the nitriding speed is less than a predetermined value can be determined as the threshold value (for example, less than 1 mm / year). For example, the depth of the nitrided layer can be measured by the "determination method based on hardness test" or the "determination method based on metal structure test" of the "method for measuring the depth of the nitrided layer of steel" prescribed in JIS G0562.

[0061] The control device 90 can also control at least one of the valve VI and the valve V3 to adjust the flow rate of oxidizer supplied to the reactor 2 and the flow rate of oxidizer supplied to the second mixer 3 so that the temperature of the mixed gas measured by the temperature sensor S2 is less than the threshold value.

[0062] In addition, in the case where the temperature of the mixed gas measured by the temperature sensor S2 is excessively high, that is, in the case where the catalyst is excessively heated due to the exothermic reaction, the control device 90 can also open the valve V2 to add nitrogen to the mixed gas as an emergency coolant.

[0063] Furthermore, a valve (not shown) may be provided on the fuel supply line L1 for adjusting the flow rate of ammonia supplied to the first mixer 1. Furthermore, pumps (not shown) may be provided on each of the lines L1, L2, and L3 for conveying fluids. These valves and pumps may be communicatively connected to the control device 90 via wired or wireless communication and may be controlled by the control device 90.

[0064] Next, the operation of the fuel preheater 10 will be described.

[0065] When the fuel preheater 10 starts operating, the control device 90 starts the operation of the heating unit H. The catalyst is heated until the temperature measured by the temperature sensor S1 reaches a temperature at which the catalyst starts to activate.

[0066] When the temperature measured by the temperature sensor reaches the catalyst activation temperature, the control device 90 controls valve V1 to start supplying the oxidant to the first mixer 1. Furthermore, the first mixer 1 receives ammonia from the fuel supply line L1. The first mixer 1 mixes the ammonia and the oxidant to produce a mixed gas. The mixed gas is supplied to the reactor 2 via the fuel supply line L1.

[0067] In addition, the control device 90 stops the operation of the heating unit H. Thereafter, the catalyst is maintained at a sufficient temperature by catalytic combustion.

[0068] At least a portion of the oxidant in the mixed gas, for example, a majority of the oxidant in the mixed gas, reacts with ammonia on the catalyst in reactor 2, causing catalytic combustion. This heats the mixed gas. The heated mixed gas is supplied to the second mixer 3 via fuel supply line L1.

[0069] The control device 90 controls valve V3 to start supplying the oxidant required for combustion in the burner B to the second mixer 3. Furthermore, the second mixer 3 receives the heated mixed gas from the fuel supply line L1. The second mixer 3 further mixes ammonia and the oxidant. The heated mixed gas is then supplied as premixed fuel to the multiple burners B via the fuel supply line L1.

[0070] The fuel preheater 10 as described above is provided with the first mixer 1 provided in the fuel supply line L1 connected to the combustion apparatus 100 that combusts the fuel containing ammonia, and the reactor 2 provided in the fuel supply line L1 downstream of the first mixer 1. The fuel supply line L1 supplies ammonia to the first mixer 1. The first mixer 1 is connected to the oxidizer supply line L2 that supplies the oxidizer, and mixes the ammonia flowing in the fuel supply line L1 and the oxidizer from the oxidizer supply line L2 to generate a mixed gas. The reactor 2 contains a catalyst that promotes a reaction of ammonia to cause an exothermic reaction. The catalyst causes an exothermic reaction by at least a part of the ammonia in the mixed gas supplied from the first mixer 1 to heat the mixed gas. According to such a structure, the mixed gas containing ammonia and heated by the exothermic reaction in the reactor 2 can be supplied to the combustion apparatus 100. The mixed gas is heated by the exothermic reaction, and therefore the ammonia in the mixed gas is also heated, and the combustion speed of ammonia is increased. Therefore, the fuel can be supplied to the combustion apparatus 100 in a state where the combustion speed is increased.

[0071] In addition, the fuel preheater 10 is provided with the second mixer 3 provided in the fuel supply line L1 downstream of the reactor 2. The second mixer 3 is connected to the oxidizer supply line L2 through the bypass line BL1, and mixes the mixed gas supplied from the reactor 2 and the oxidizer supplied from the bypass line BL1. According to such a structure, the amount of the oxidizer supplied from the oxidizer supply line L2 to the reactor 2 can be adjusted more finely.

[0072] In addition, the fuel preheater 10 is provided with the valve V1 provided in the oxidizer supply line L2 to adjust the flow rate of the oxidizer, the temperature sensor S2 provided in the fuel supply line L1 downstream of the reactor 2 to measure the temperature of the mixed gas, and the control device 90 communicably connected to the valve V1 and the temperature sensor S2. The control device 90 stores a predetermined threshold value associated with a temperature at which the material forming the fuel supply line L1 starts nitriding. 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 less than the threshold value. According to such a structure, the embrittlement of the fuel supply line L1 caused by nitriding can be suppressed.

[0073] In addition, the reactor 2 can contain a heating unit H for heating the catalyst, and the heating unit H can contain a heater. According to such a structure, the catalyst can be rapidly heated to a temperature at which the catalyst starts to be activated.

[0074] Alternatively or additionally, the heating unit H can include a first heat exchanger that heats the catalyst using exhaust gas from the combustion apparatus 100. According to such a structure, the catalyst can be rapidly heated to a temperature at which the catalyst starts to be activated, and the exhaust gas can be reused.

[0075] Alternatively or additionally, the heating unit H can include a second heat exchanger that heats the catalyst using steam drawn from the combustion device 100. According to such a configuration, the catalyst can be rapidly heated to a temperature at which the catalyst starts to activate.

[0076] In addition, the fuel preheater 10 supplies the mixed gas to the plurality of burners B of the combustion device 100. According to this configuration, it is not necessary to provide the fuel preheater for each burner B.

[0077] In addition, the exothermic reaction in the catalyst of the reactor 2 is catalytic combustion. According to such a configuration, the reaction in the reactor 2 proceeds as surface reaction-based flameless combustion, and thus is highly safe. In addition, by changing the flow rate of the oxidizer, it is possible to change the air ratio in the reactor 2, and control the temperature of the mixed gas. It is possible to increase the temperature of the mixed gas, and improve the ignition property of the ammonia that is a flame retardant in the burner B, and the combustion stability.

[0078] In addition, the fuel preheater 10 described above can be provided to an existing combustion device 100. The method of installing the fuel preheater 10 of the present embodiment to the combustion device 100 includes preparing a first mixer 1 configured to mix ammonia and an oxidizer, preparing a reactor 2 that contains a catalyst that causes an exothermic reaction based on ammonia, and providing the first mixer 1 to a fuel supply line L1 that is connected to the combustion device 100 that combusts a fuel containing ammonia. Thereby, the fuel supply line L1 supplies ammonia to the first mixer 1. In addition, the method of the present embodiment includes connecting an oxidizer supply line L2 that supplies an oxidizer to the first mixer 1. Thereby, the first mixer 1 mixes the ammonia flowing in the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to generate a mixed gas. In addition, the method of the present embodiment includes providing the reactor 2 to the fuel supply line L1 downstream of the first mixer 1. Thereby, the catalyst causes an exothermic reaction by at least a portion of the ammonia in the mixed gas supplied from the first mixer 1, and heats the mixed gas. According to such a configuration, it is possible to supply the fuel to the existing combustion device 100 in a state in which the combustion speed is improved without a large amount of work.

[0079] Further, in Figure 1 and the following Figure 2 and Figure 3 , the fuel preheaters 10, 10A, and 10B have the constituent elements surrounded by the broken lines. Therefore, the method of installing the fuel preheater 10, 10A, or 10B of the present disclosure to the combustion device 100 can further include providing the constituent elements in the broken lines other than the first mixer 1 and the reactor 2 to the existing fuel supply line L1.

[0080] Next, other embodiments will be described.

[0081] Figure 2 is a schematic view of a combustion device 100 provided with the fuel preheater 10A of the second embodiment. The fuel preheater 10A differs from the fuel preheater 10 of the first embodiment in that a bypass line (second bypass line) BL2 of ammonia and a third mixer 4 are provided instead of the bypass line BL1 of oxidant and the second mixer 3. As for other structures, the fuel preheater 10A can be the same as the fuel preheater 10.

[0082] The third mixer 4 is provided in the fuel supply line L1 downstream of the reactor 2. The third mixer 4 can also be provided in the existing fuel supply line L1 connected to the existing combustion device 100. The third mixer 4 is, for example, a gas mixer. The third mixer 4 receives the heated mixed gas from the reactor 2.

[0083] The third mixer 4 is connected to a position in the fuel supply line L1 upstream of the first mixer 1 via the bypass line BL2. 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 part of the ammonia flowing in the fuel supply line L1 is supplied to the first mixer 1, and the remaining part of the ammonia is supplied to the third mixer 4.

[0084] In the present embodiment, a valve (second valve) V4 is provided in the fuel supply line L1 between the connection portion with the bypass line BL2 and the first mixer 1. The valve V4 is communicably connected to the control device 90 in a wired or wireless manner and is controlled by the control device 90. The control device 90 adjusts the flow rate of the ammonia supplied to the first mixer 1 by controlling the opening degree of the valve V4.

[0085] A valve V5 is provided in the bypass line BL2. The valve V5 is communicably connected to the control device 90 in a wired or wireless manner and is controlled by the control device 90. The control device 90 adjusts the flow rate of the ammonia supplied to the third mixer 4 by controlling the opening degree of the valve V5.

[0086] The third mixer 4 further mixes the mixed gas flowing in the fuel supply line L1 with the ammonia supplied from the bypass line BL2. The mixed gas flows in the fuel supply line L1 and is supplied as fuel to the combustor B.

[0087] For example, the control device 90 can control the valve V4 to adjust the flow rate of the ammonia distributed from the fuel supply line L1 to the first mixer 1, that is, the flow rate of the ammonia supplied to the reactor 2, so that most of the ammonia in the mixed gas supplied to the reactor 2 is used as the reaction (2) of the exothermic reaction. In addition, the control device 90 can also control the valve V5 as needed.

[0088] For example, in a case where the reactor 2 needs to further heat the mixed gas, the control device 90 can increase the flow rate of ammonia supplied from the fuel supply line Ll to the reactor 2. In contrast, for example, in a case where the reactor 2 excessively heats the mixed gas, the control device 90 can decrease the flow rate of the oxidizing agent supplied from the fuel supply line Ll to the reactor 2.

[0089] The ammonia required for combustion in the combustor B is supplied from the fuel supply line Ll to the third mixer 4 via the bypass line BL2, 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 distributed from the fuel supply line Ll to the bypass line BL2, that is, the amount of ammonia supplied to the third mixer 4. In addition, the control device 90 can also control the valve V4 as needed.

[0090] For example, in a case where the combustor B needs more ammonia for combustion, the control device 90 can also increase the flow rate of ammonia supplied from the fuel supply line Ll to the third mixer 4. In contrast, for example, in a case where the amount of ammonia supplied to the combustor B is excessive, the control device 90 can also decrease the flow rate of ammonia supplied from the fuel supply line Ll to the third mixer 4.

[0091] In addition, the control device 90 can also control at least one of the valve V4 and the valve V5 to adjust the flow rate of ammonia supplied to the reactor 2 and the flow rate of ammonia supplied to the third mixer 4 so that the temperature of the mixed gas measured by the temperature sensor S2 is less than a threshold value (for example, 400°C), as in the first embodiment.

[0092] The fuel preheater 10A as described above functions substantially the same as the fuel preheater 10 of the first embodiment. In addition, the fuel preheater 10A is provided with the third mixer 4 disposed in the fuel supply line Ll downstream of the reactor 2. The third mixer 4 is connected to a position in the fuel supply line Ll upstream of the first mixer 1 via the bypass line BL2, and mixes the mixed gas supplied from the reactor 2 with ammonia supplied from the bypass line BL2. According to such a structure, it is possible to more finely adjust the amount of ammonia supplied from the fuel supply line Ll to the reactor 2.

[0093] Further, the fuel preheater 10A is provided with: a valve V4 provided in the fuel supply line L1 upstream of the first mixer 1, which adjusts the flow rate of ammonia supplied to the first mixer 1; a temperature sensor S2 provided in the fuel supply line L1 downstream of the reactor 2, which measures the temperature of the mixed gas; and a control device 90 communicably 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 the material forming the fuel supply line L1 starts nitriding. The control device 90 controls the valve V4 to adjust 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 less than the threshold value. According to such a configuration, the embrittlement of the fuel supply line L1 caused by nitriding can be suppressed.

[0094] Figure 3 is a schematic view of a combustion device 100 provided with a fuel preheater 10B of the third embodiment. The fuel preheater 10B differs from the fuel preheater 10 of the first embodiment in that it is not provided with the bypass line BL1 and the second mixer 3. As for other configurations, the fuel preheater 10B can be the same as the fuel preheater 10.

[0095] In the present embodiment, each burner B of the combustion device 100 is of a diffusion combustion type. Air required for diffusion combustion is supplied to each burner B. The combustion device 100 can include an air regulator and a damper, and other unillustrated constituent elements for adjusting the amount of air supplied to each burner B. Further, in Figure 3 In the present embodiment, air is shown only for the uppermost burner B.

[0096] For example, the control device 90 controls the valve V1 to adjust the amount of oxidizer supplied from the oxidizer supply line L2 to the reactor 2 via the first mixer 1 so that most of the oxidizer in the mixed gas supplied to the reactor 2 is used as the reaction (2) of the exothermic reaction.

[0097] Further, as in the first embodiment, the control device 90 controls the valve V1 to adjust the flow rate of oxidizer 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 (for example, 400°C).

[0098] The fuel preheater 10B as described above has substantially the same effects as the fuel preheater 10 of the first embodiment.

[0099] The above-described embodiments have been described with reference to the drawings, but the present disclosure is not limited to the above-described embodiments. It is obvious to those skilled in the art that various modifications or corrections are conceivable within the scope described in the claims, and it is understood that they also belong to the technical scope of the present disclosure. In addition, the procedures of the method of the above-described embodiments can also be performed in a different order from the above-described order, as long as there is no technical contradiction.

[0100] The present disclosure can contribute to the use of ammonia in relation to the reduction of CO2 emissions, and thus, for example, can contribute to the achievement of SDG 7 "Ensure access to affordable, reliable, sustainable, and modern energy for all" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0101] Explanation of Reference Signs

[0102] 1 first mixer,

[0103] 2 reactor,

[0104] 3 second mixer,

[0105] 4 third mixer,

[0106] 10 fuel preheater,

[0107] 10A fuel preheater,

[0108] 10B fuel preheater,

[0109] 90 control device,

[0110] 100 combustion device,

[0111] B burner,

[0112] BL1 bypass line (first bypass line),

[0113] BL2 bypass line (second bypass line),

[0114] H heating unit,

[0115] L1 fuel supply line,

[0116] L2 oxidant supply line,

[0117] L3 nitrogen supply line,

[0118] S1 temperature sensor,

[0119] S2 temperature sensor,

[0120] V1 valve (first valve),

[0121] V4 valve (second valve).

Claims

1. A fuel preheater, characterized in that: The fuel preheater has: a first mixer provided on a fuel supply line connected to a combustion device that burns a fuel containing ammonia, the fuel supply line supplying ammonia to the first mixer, the first mixer being connected to an oxidant supply line supplying an oxidant, and mixing ammonia flowing through the fuel supply line with the oxidant from the oxidant supply line to generate a mixed gas; and A reactor is 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 with at least a portion of the ammonia in the mixed gas supplied from the first mixer, and heating the mixed gas.

2. The fuel preheater according to claim 1, characterized in that The fuel preheater includes a second mixer provided downstream of the reactor in the fuel supply line, the second mixer being connected to the oxidant supply line via a first bypass line and mixing the mixed gas supplied from the reactor with the oxidant supplied from the first bypass line.

3. The fuel preheater according to claim 1 or 2, characterized in that: The fuel preheater has: a first valve, disposed in the oxidant supply line, for adjusting a flow rate of the oxidant supplied to the first mixer; a temperature sensor, disposed in the fuel supply line downstream of the reactor, for measuring the temperature of the mixed gas; as well as A control device is communicatively connected to the first valve and the temperature sensor, the control device storing a predetermined threshold value associated with the temperature at which the material forming the fuel supply pipeline begins to nitride, and the control device controls the first valve to adjust the flow rate of the oxidant supplied to the first mixer so that the temperature of the mixed gas measured by the temperature sensor is less than the threshold value.

4. The fuel preheater according to claim 1, characterized in that The reactor includes a heating unit for heating the catalyst, and the heating unit includes a heater.

5. The fuel preheater according to claim 1, characterized in that The reactor includes a heating unit for heating the catalyst, and the heating unit includes a first heat exchanger for heating the catalyst by exhaust gas from the combustion device.

6. The fuel preheater according to claim 1, characterized in that The reactor comprises a heating unit for heating the catalyst, the heating unit comprising a second heat exchanger for heating the catalyst by steam extracted from the combustion device.

7. The fuel preheater according to claim 1, characterized in that The fuel preheater has: a third mixer disposed 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 via a second bypass line, and mixing the mixed gas supplied from the reactor with the ammonia supplied from the second bypass line.

8. The fuel preheater according to claim 1 or 7, characterized in that: The fuel preheater has: a second valve provided in the fuel supply line upstream of the first mixer to adjust a flow rate of ammonia supplied to the first mixer; a temperature sensor, disposed in the fuel supply line downstream of the reactor, for measuring the temperature of the mixed gas; as well as 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 nitridation of a material forming the fuel supply line begins, and 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 less than the threshold value.

9. The fuel preheater according to claim 1, characterized in that The fuel preheater supplies the mixed gas to a plurality of burners of the combustion equipment.

10. The fuel preheater according to claim 1, characterized in that The exothermic reaction in the catalyst of the reactor is catalytic combustion.

11. A method for installing a fuel preheater on a combustion device, characterized in that: include: preparing a first mixer configured to mix ammonia and an oxidant; preparing a reactor containing a catalyst for inducing an exothermic ammonia-based reaction; The first mixer is provided in a fuel supply line connected to a combustion device that burns ammonia-containing fuel, and the fuel supply line supplies ammonia to the first mixer; connecting an oxidant supply line for supplying an oxidant to the first mixer, the first mixer mixing ammonia flowing through the fuel supply line with the oxidant from the oxidant supply line to generate a mixed gas; and The reactor is provided in the fuel supply line downstream of the first mixer, and the catalyst causes the exothermic reaction with at least a portion of the ammonia in the mixed gas supplied from the first mixer, thereby heating the mixed gas.

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