Fuel preheater

Abstract

The fuel preheater 10 comprises a first mixer 1, which is provided in a fuel supply line L1 connected to a combustion unit 100 that burns fuel comprising ammonia, wherein the fuel supply line L1 supplies ammonia to the first mixer 1, the first mixer 1 being connected to an oxidizer supply line L2 which supplies an oxidizer, and mixing the ammonia flowing in the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to produce a mixed gas, and a reactor 2, which is provided downstream of the first mixer 1 in the fuel supply line L1, wherein the reactor 2 comprises a catalyst which promotes a reaction of the ammonia and which causes an exothermic reaction, wherein the catalyst causes the exothermic reaction with at least a portion of the ammonia in the mixed gas supplied by the first mixer 1, and the Mixed gas heated.

Description

Technical field

[0001] The present disclosure relates to a fuel preheater. The present application claims priority based on Japanese patent application No. 2023-097818, filed on June 14, 2023, the contents of which are incorporated herein by reference. State of the art

[0002] In a combustion plant, a catalyst can be used to promote combustion. For example, patent literature 1 discloses a catalytic flameless combustion device. In this device, a mixture of air and natural gas is burned over a catalyst that is placed in a combustion chamber.

[0003] Furthermore, patent literature 2 discloses a catalytic combustion burner. In this burner, a mixture of gaseous fuel, such as natural gas or town gas, and air is burned over a catalyst.

[0004] Furthermore, patent literature 3 discloses a burner section of a gas turbine. In this gas turbine, a mixture of natural gas and air is oxidized by a catalyst and subsequently combusted by a pilot flame and a main flame. Citation list for patent literature Patent Literature 1: JP 2019-511696 A Patent Literature 2: JP 2019-529847 A Patent Literature 3: JP H11-509307 A Brief description of the technical problem

[0005] Ammonia is known as a fuel that does not emit CO2. However, the combustion rate of ammonia is slower than that of other fuels, such as natural gas. Therefore, when ammonia is used in a combustion plant, it is desirable to increase the combustion rate.

[0006] An object of the present invention is to provide, when ammonia is used as a fuel in a combustion plant, a fuel preheater that can supply the fuel to the combustion plant at an increased combustion rate. It is also an object of the present disclosure to provide a method for incorporating such a fuel preheater into a combustion plant. Solution to the problem

[0007] A fuel preheater in accordance with one aspect of the present disclosure comprises a first mixer provided in a fuel supply line connected to a combustion plant that burns fuel comprising ammonia, the fuel supply line supplying ammonia to the first mixer, the first mixer being connected to an oxidizer supply line supplying an oxidizer, the first mixer mixing the ammonia flowing into the fuel supply line with the oxidizer from the oxidizer supply line to produce a mixed gas, and a reactor provided downstream of the first mixer in the fuel supply line, the reactor comprising a catalyst promoting a reaction of the ammonia and causing an exothermic reaction, the catalyst causing the exothermic reaction with at least a portion of the ammonia in the mixed gas.which is supplied by the first mixer and heats the mixed gas.

[0008] The fuel preheater may include a second mixer provided downstream of the reactor in the fuel supply line, wherein the second mixer is connected to the oxidizer supply line by a first bypass line, and mixes the mixed gas supplied from the reactor with the oxidizer supplied by the first bypass line.

[0009] The fuel preheater can include a first valve provided in the oxidizer feed line that adjusts the flow rate of the oxidizer supplied to the first mixer, a temperature sensor provided downstream of the reactor in the fuel feed line that measures the temperature of the mixed gas, and a controller that is communicatively linked to the first valve and the temperature sensor, wherein the controller stores a predetermined limit value associated with a temperature at which a material forming the fuel feed line begins to be nitrated, and the controller controls 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 limit value.

[0010] The reactor may include a heating device for heating the catalyst, and the heating device may include a heater.

[0011] Alternatively or additionally, the heating device can include a first heat exchanger that heats the catalyst using exhaust gas from the combustion system.

[0012] Alternatively or additionally, the heating device can include a second heat exchanger that heats the catalyst using steam taken from the combustion system.

[0013] The fuel preheater may include a third mixer located downstream of the reactor in the fuel supply line, wherein the third mixer is connected to a position upstream of the first mixer in the fuel supply line by a second bypass line and mixes the mixed gas supplied from the reactor with the ammonia supplied from the second bypass line.

[0014] The fuel preheater can include a second valve located upstream of the first mixer in the fuel supply line, which adjusts the flow rate of the ammonia supplied to the first mixer; a temperature sensor located downstream of the reactor in the fuel supply line, which measures the temperature of the mixed gas; and a control unit that is communicatively connected to the second valve and the temperature sensor, wherein the control unit stores a predetermined limit value associated with a temperature at which a material forming the fuel supply line begins to nitrate; and the control unit controls the second valve to adjust the flow rate of the ammonia supplied to the first mixer so that the temperature of the mixed gas measured by the temperature sensor is below the limit value.

[0015] The fuel preheater can supply the mixed gas to a large number of burners in the combustion plant.

[0016] The exothermic reaction in the reactor's catalyst can be a catalytic combustion.

[0017] Another aspect of the present disclosure is a method of installing a fuel preheater in a combustion plant, the method comprising preparing a first mixer designed to mix ammonia and an oxidizer, preparing a reactor comprising a catalyst that initiates an exothermic reaction with ammonia, installing the first mixer in a fuel supply line connected to a combustion plant that burns fuel comprising ammonia, the fuel supply line supplying ammonia to the first mixer, connecting an oxidizer supply line supplying an oxidizer to the first mixer, the first mixer mixing the ammonia flowing in the fuel supply line with the oxidizer from the oxidizer supply line to produce a mixed gas, and installing the reactor downstream of the first mixer in the fuel supply line.wherein the catalyst initiates the exothermic reaction with at least some of the ammonia in the mixed gas supplied by the first mixer and heats the mixed gas. Advantageous effects of the invention

[0018] According to the present disclosure, when ammonia is used as fuel in a combustion plant, the fuel can be supplied to the combustion plant at an increased combustion rate. Brief description of drawings Fig. Figure 1 is a schematic diagram of a combustion plant comprising a fuel preheater according to a first embodiment. Fig. Figure 2 is a schematic diagram of the combustion plant, which includes a fuel preheater according to a second embodiment. Fig. Figure 3 is a schematic diagram of the combustion plant, which includes a fuel preheater according to a third embodiment. Description of embodiments

[0019] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0020] Specific dimensions, materials, and numerical values ​​described in the embodiments are merely examples for better understanding and do not limit the present disclosure unless otherwise stated. In this specification and the drawings, duplicate descriptions for components that have essentially the same functions and designs have been avoided by assigning the same symbol. Furthermore, components not directly related to the present disclosure have been omitted from the figures.

[0021] Fig. Figure 1 is a schematic diagram of a combustion plant 100 comprising a fuel preheater 10 according to a first embodiment. The fuel preheater 10 is installed in a fuel supply line L1, which is connected to the combustion plant 100. Gas containing ammonia flows in the fuel supply line L1. For example, the combustion plant 100 can be a boiler, an industrial furnace, or an incinerator. The combustion plant 100 is not limited to these and can be a variety of plants that use ammonia as fuel. The combustion plant 100 can be an existing plant. In another embodiment, the combustion plant 100 can be a newly constructed plant. For example, the combustion plant 100 includes one or more burners B.

[0022] Burner B combusts fuel containing ammonia. For example, burner B can burn a mixed fuel of ammonia and another fuel, such as pulverized coal. It is also possible for burner B to burn only ammonia. Furthermore, burner B can burn fuel that does not contain ammonia, if necessary.

[0023] For example, the fuel preheater 10 comprises a first mixer 1, a reactor 2, a second mixer 3, and a control unit 90. The fuel preheater 10 may also include other components (not shown).

[0024] The first mixer 1 is provided in the fuel supply line L1. For example, the first mixer 1 can be installed for an existing fuel supply line L1 that is connected to an existing combustion plant 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.

[0025] An oxidizer supply line L2 is connected to the first mixer 1. The oxidizer supply line L2 supplies an oxidizer (for example, air) to the first mixer 1.

[0026] A valve (first valve) V1 is provided in the oxidizer supply line L2. Valve V1 is connected to the controller 90 either by wire or wirelessly and is controlled by the controller 90. The controller 90 adjusts the flow rate of the oxidizer supplied to the first mixer 1 by controlling the opening degree of valve V1.

[0027] The first mixer 1 mixes the ammonia flowing in fuel supply line L1 with the oxidizer supplied by oxidizer supply line L2, producing a mixed gas containing both ammonia and oxidizer. This mixed gas flows through fuel supply line L1 and is fed to reactor 2.

[0028] A nitrogen supply line L3 is connected to the first mixer 1. The nitrogen supply line L3 supplies nitrogen to the first mixer 1.

[0029] A valve V2 is provided in the nitrogen supply line L3. Valve V2 is connected to the controller 90 either by wire or wirelessly and is controlled by the controller 90. The controller 90 adjusts the flow rate of the nitrogen supplied to the first mixer 1 by controlling the opening degree of valve V2.

[0030] Reactor 2 is located downstream of the first mixer 1 in the fuel supply line L1. Like the first mixer 1, reactor 2 can also be installed for an existing fuel supply line L1 connected to an existing combustion unit 100. Reactor 2 receives the mixed gas from the first mixer 1. Reactor 2 includes a catalyst that promotes a reaction of ammonia and initiates an exothermic reaction. Specifically, the catalyst promotes the reaction of at least a portion of the ammonia in the mixed gas supplied by the first mixer 1, initiating 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.

[0031] For example, the catalyst can include a transition element (also called a transition metal). For instance, the catalyst can be a noble metal, such as ruby ​​(Ru), or a non-noble metal, such as iron (Fe), cobalt (Co), nickel (Ni), or a non-noble metal, also from the transition metal group. Non-noble metals can be highly active when combined with a specific support. For example, an oxide, such as Al₂O₃ or SiO₂, can be used as a support. Additionally, a support that inhibits sintering, such as ceo₂, can be used if necessary.

[0032] A temperature sensor S1 is provided at reactor 2. The temperature sensor S1 is designed to measure the temperature of the catalyst. The temperature sensor S1 is connected to the controller 90 via a wire or wirelessly and transmits measured data to the controller 90.

[0033] Reactor 2 is equipped with a heating device H. The heating device H heats the catalyst. For example, the heating device H can include an electric heater. Alternatively or additionally, the heating device H can include a first heat exchanger that heats the catalyst using exhaust gas from the combustion unit 100. Alternatively or additionally, if the combustion unit 100 includes a boiler, the heating device H can include a second heat exchanger that heats the catalyst using steam taken from the combustion unit 100. The heating device H is communicatively connected to the control unit 90 by means of a wire or wirelessly and is controlled by the control unit 90.

[0034] For example, when the fuel preheater 10 starts operating, the controller 90 starts the heating unit H to heat the catalyst until the temperature measured by the temperature sensor S1 reaches a temperature at which the catalyst begins to be active (for example, 400 °C). When the temperature measured by the temperature sensor S1 reaches the temperature at which the catalyst begins to be active, the controller 90 stops the operation of the heating unit H. Afterward, the catalyst is kept at a sufficient temperature by catalytic combustion.

[0035] The second mixer 3 is located downstream of reactor 2 in the fuel supply line L1. Like the first mixer 1 and reactor 2, the second mixer 3 can also be installed for an existing fuel supply line L1 that is connected to an existing combustion unit 100. For example, the second mixer 3 is a gas mixer. The second mixer 3 receives the heated mixed gas from reactor 2.

[0036] The second mixer 3 is connected to the oxidizer supply line L2 via a bypass line (first bypass line) BL1. The bypass line BL1 connects the oxidizer supply line L2 directly to the second mixer 3, bypassing the first mixer 1 and the reactor 2. Accordingly, at least a portion of the oxidizer flowing in the oxidizer supply line L2 is fed to the first mixer 1, and the remainder is fed to the second mixer 3.

[0037] A valve V3 is provided in the bypass line BL1. Valve V3 is connected to the controller 90 either wired or wirelessly and is controlled by the controller 90. The controller 90 adjusts the flow rate of the oxidizer supplied to the second mixer 3 by controlling the opening degree of valve V3.

[0038] The second mixer 3 further mixes the mixed gas flowing in the fuel supply line L1 with the oxidizer supplied by the bypass line BL1. The mixed gas flows through the fuel supply line L1 and is fed to the burners B as fuel (premix combustion system). In another embodiment, the burner B can be a diffusion combustion system.

[0039] A temperature sensor S2 is provided at a position downstream of the reactor 2 in the fuel supply line L1, specifically at a position downstream of the second mixer 3 in the present embodiment. The temperature sensor S2 is designed to measure the temperature of the mixed gas flowing in the fuel supply line L1. The temperature sensor S2 is communicatively connected to the controller 90 by means of a wire or wirelessly and transmits measured data to the controller 90.

[0040] The fuel supply line L1 branches into a multitude of lines at a position downstream of the temperature sensor S2 and is connected to each of the multitude of burners B.

[0041] The controller 90 controls the fuel preheater 10. The controller 90 can also control at least some components in the combustion unit 100. Furthermore, the combustion unit 100 can, for example, include a main controller (not shown), and the controller 90 can communicate with the main controller. The controller 90 comprises components such as a processor 90a, a memory 90b, and a connector 90c, and these components are interconnected by bus lines. For example, the processor 90a comprises a CPU (Central Processing Unit). For example, the memory 90b comprises a hard disk, a read-only memory (ROM) in which programs are stored, and a working memory (RAM). The controller 90 is communicatively connected to each component of the fuel preheater 10 by means of a wire or wirelessly via the connector 90c.For example, the controller 90 can further include other components, such as a display, like an LCD or a touch panel, and an input device, like a keyboard, a button, and a touch panel. For example, operation of the controller 90 can be realized by executing programs stored in memory 90b on the processor 90a.

[0042] The catalyst in reactor 2 promotes the reaction of ammonia, which causes the following reactions (1), (2) or a combination thereof. (1) NH3 → 1.5H2 + 0.5N2 ΔH = 45.4 (kJ / mol) (2) 2NH3 + 1.502 → N2 + 3H2O ΔH = -382.6 (kJ / mol)

[0043] For example, in the present embodiment, the catalyst can initiate both reactions (1) and (2). For example, the controller 90 can control the valve V1 to adjust the amount of oxidizer supplied from the oxidizer supply line L2 to the first mixer 1, i.e., the amount of oxidizer supplied to the reactor 2, so that the majority of the oxidizer in the mixed gas supplied to the reactor 2 is used by reaction (2), which is an exothermic reaction. The controller 90 can also control the valve V3 if necessary.

[0044] For example, if reactor 2 requires more oxidizer for catalytic combustion, control 90 increases the flow rate of the oxidizer supplied to reactor 2 from oxidizer supply line L2. Conversely, if the amount of oxidizer supplied to reactor 2 is excessive, control 90 decreases the flow rate of the oxidizer supplied to reactor 2 from oxidizer supply line L2.

[0045] The oxidizer required for combustion in burners B is supplied from oxidizer supply line L2 to the second mixer 3 via bypass line BL1 and mixed with the heated mixed gas in the second mixer 3. Control unit 90 operates valve V3 to adjust the amount of oxidizer supplied from oxidizer supply line L2 to bypass line BL1, i.e., the amount of oxidizer supplied to the second mixer 3. Control unit 90 can also control valve V1 if necessary.

[0046] For example, if the burners B require more oxidizer for combustion, the controller 90 can increase the flow rate of the oxidizer supplied from the oxidizer supply line L2 to the second mixer 3. Conversely, if the amount of oxidizer supplied to the burners B is excessive, the controller 90 can, for example, decrease the flow rate of the oxidizer supplied from the oxidizer supply line L2 to the second mixer 3.

[0047] Furthermore, the controller 90 stores a predetermined limit value in memory 90b. This limit 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 made of steel, such as stainless steel. It is known that many steels nitride when exposed to an ammonia-containing environment at temperatures essentially between 400 °C and 600 °C. Thus, many steels will not nitride, even when exposed to an ammonia-containing environment, if the temperature is below the aforementioned range. Specifically, the limit value may, for example, be 400 °C.

[0048] Furthermore, the limit can be determined experimentally. For example, a sample made of the same material that forms 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 (e.g., one month, several months, one year, or several years). Afterward, the nitrated shell depth of the sample is measured, and a nitration rate per year (mm / year) is calculated. The experiment is performed at several temperatures. For example, a temperature at which the nitration rate is less than a predetermined value can be determined as the limit (e.g., less than 1 mm / year).For example, the nitrided shell depth can be measured by the “Method of Measurement by Hardness Test” or the “Method of Measurement by Metallographic Test” of the “Method of Measurement of Nitrided Shell Depth for Iron and Steel” defined by JIS G0562.

[0049] The control unit 90 can control at least one of the valves V1 and V3 to adjust the flow rate of the oxidizer supplied to reactor 2 and the flow rate of the oxidizer supplied to the second mixer 3, so that the temperature of the mixed gas, measured by the temperature sensor S2, is below the limit value.

[0050] If the temperature of the mixed gas, measured by the temperature sensor S2, is excessively high, i.e., if the catalyst is excessively heated by the exothermic reaction, the control unit 90 can open valve V2 to add nitrogen as an emergency coolant to the mixed gas.

[0051] It should be noted that the fuel supply line L1 may be equipped with a valve (not shown) for adjusting the flow rate of ammonia supplied to the first mixer 1. Furthermore, each of the lines L1, L2, and L3 may be equipped with a pump (not shown) for pumping fluid. The valve and pumps may be connected to the controller 90 via a wire or wirelessly and may be controlled by the controller 90.

[0052] Next, the operation of the fuel preheater 10 will be described.

[0053] When the fuel preheater 10 starts operation, the control unit 90 starts operation of the heating device H. The catalyst is heated until the temperature measured by the temperature sensor S1 reaches the temperature at which the catalyst begins to be active.

[0054] When the temperature measured by the temperature sensor reaches the temperature at which the catalyst becomes active, the control unit 90 activates valve V1 and begins 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 with the oxidizer to produce the mixed gas. The mixed gas is then supplied to reactor 2 via the fuel supply line L1.

[0055] Control unit 90 stops the operation of heating device H. Afterwards, the catalyst is kept at a sufficient temperature by catalytic combustion.

[0056] At least a portion of the oxidizer in the mixed gas, i.e., most of the oxidizer in the mixed gas, reacts with the ammonia on the catalyst in reactor 2, initiating catalytic combustion. This heats the mixed gas. The heated mixed gas is fed through fuel supply line L1 to the second mixer 3.

[0057] Control unit 90 controls valve V3 to start supplying the second mixer 3 with the oxidizer required for combustion in the burners B. The second mixer 3 also receives the heated mixed gas from the fuel supply line L1. The second mixer 3 further mixes the ammonia with the oxidizer. The heated mixed gas is then supplied to the multiple burners B via the fuel supply line L1 as a premixed fuel.

[0058] The fuel preheater 10, as described above, comprises the first mixer 1, which is provided in the fuel supply line L1 connected to the combustion unit 100, which burns fuel comprising ammonia, and the reactor 2, which is provided downstream of the first mixer 1 in the fuel supply line L1. The fuel supply line L1 feeds the ammonia to the first mixer 1. The first mixer 1 is connected to the oxidizer supply line L2, which supplies the oxidizer, and mixes the ammonia flowing in the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to produce the mixed gas. The reactor 2 comprises the catalyst, which promotes the reaction of the ammonia and initiates the exothermic reaction. The catalyst initiates the exothermic reaction with at least some of the ammonia in the mixed gas supplied by the first mixer 1, and heats the mixed gas.According to this configuration, the mixed gas, which contains ammonia and is heated by the exothermic reaction in reactor 2, can be fed to combustion unit 100. Since the mixed gas is heated by the exothermic reaction, the ammonia in the mixed gas is also heated, thereby increasing the combustion rate of ammonia. Thus, the fuel can be fed to combustion unit 100 with the increased combustion rate.

[0059] Furthermore, the fuel preheater 10 includes the second mixer 3, which is located downstream of reactor 2 in the fuel supply line L1. The second mixer 3 is connected to the oxidizer supply line L2 via the bypass line BL1 and mixes the mixed gas supplied by reactor 2 with the oxidizer supplied by the bypass line BL1. This design allows for more precise control of the amount of oxidizer supplied from the oxidizer supply line L2 to reactor 2.

[0060] Furthermore, the fuel preheater 10 comprises the valve V1, which is provided in the oxidizer supply line L2 and adjusts the flow rate of the oxidizer; the temperature sensor S2, which is provided downstream of the reactor 2 in the fuel supply line L1 and measures the temperature of the mixed gas; and the controller 90, which is communicatively connected to the valve V1 and the temperature sensor S2. The controller 90 stores the predetermined limit value associated with the temperature at which the material forming the fuel supply line L1 begins to nitrate. The controller 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, as measured by the temperature sensor S2, remains below the limit value. According to this design, embrittlement of the fuel supply line L1 due to nitriding can be prevented.

[0061] Furthermore, reactor 2 includes the heating device H, which heats the catalyst, and the heating device H may include a heater. According to such a design, the catalyst can be heated quickly to the temperature at which it begins to be active.

[0062] Alternatively or additionally, the heating device H can include the first heat exchanger in which the catalyst is heated by the exhaust gas from the combustion unit 100. According to such a design, the catalyst can be heated quickly to the temperature at which it begins to be active, and the exhaust gas can be reused.

[0063] Alternatively or additionally, the heating device H can include the second heat exchanger, which heats the catalyst with the steam taken from the combustion unit 100. According to such a design, the catalyst can be heated quickly to the temperature at which it begins to be active.

[0064] Furthermore, the fuel preheater 10 supplies the mixed gas to the multiple burners B in the combustion plant 100. According to this design, it is not necessary to provide a fuel preheater for each burner B.

[0065] Furthermore, the exothermic reaction at the catalyst of reactor 2 is catalytic combustion. According to this design, flameless combustion is carried out as the primary surface reaction in reactor 2, thereby increasing safety. Additionally, the air-fuel ratio in reactor 2 can be changed by altering the flow rate of the oxidizer, and the temperature of the mixed gas can be controlled. Increasing the temperature of the mixed gas improves the ignitability and combustion stability of ammonia, which is flame-retardant, in burners B.

[0066] Furthermore, the fuel preheater 10 can be installed in an existing combustion plant 100 as described above. The process of installing the fuel preheater 10 in the combustion plant 100 comprises preparing the first mixer 1, which is designed to mix ammonia and the oxidizer; preparing the reactor 2, which includes the catalyst that initiates the exothermic reaction with ammonia; and installing the first mixer 1 in the fuel supply line L1, which is connected to the combustion plant 100, which burns fuel comprising ammonia. The fuel supply line L1 feeds the ammonia to the first mixer 1. The process also includes connecting the oxidizer supply line L2, which supplies the oxidizer, to the first mixer 1. This allows the first mixer 1 to mix the ammonia flowing in the fuel supply line L1 with the oxidizer from the oxidizer supply line L2 to produce the mixed gas.The process also includes installing reactor 2 in the fuel supply line L1 downstream of the first mixer 1. This causes the catalyst to initiate an exothermic reaction with at least some of the ammonia in the mixed gas supplied by the first mixer 1, thus heating the mixed gas. According to this design, the fuel can be supplied to the existing combustion plant 100 with an increased combustion rate without major construction work.

[0067] It should be noted that in Fig. 1 and below Fig. 2 and Fig. 3. The fuel preheaters 10, 10A, and 10B comprise components enclosed by dashed lines. Accordingly, the method of installing the fuel preheater 10, 10A, or 10B in the combustion plant 100 according to the present disclosure may further comprise installing components enclosed by dashed lines other than the first mixer 1 and the reactor 2 in the existing fuel supply line L1.

[0068] Other embodiments will be described next.

[0069] Fig. Figure 2 is a schematic diagram of the combustion plant 100, which includes a fuel preheater 10A according to a second embodiment. The fuel preheater 10A differs from the fuel preheater 10 of the first embodiment in that it has a bypass line (second bypass line) BL2 for ammonia and a third mixer 4 instead of the bypass line BL1 for the oxidizer and the second mixer 3. With respect to other configurations, the fuel preheater 10A can be the same as the fuel preheater 10.

[0070] The third mixer 4 is located downstream of reactor 2 in the fuel supply line L1. The third mixer 4 can be installed in an existing fuel supply line L1 that is connected to an existing combustion unit 100. For example, the third mixer 4 is a gas mixer. The third mixer 4 receives the heated mixed gas from reactor 2.

[0071] The third mixer 4 is connected to the fuel supply line L1 at a position 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. Accordingly, at least a portion of the ammonia flowing in the fuel supply line L1 is fed to the first mixer 1, and the remainder is fed to the third mixer 4.

[0072] In the present embodiment, a valve (second valve) V4 is provided in the fuel supply line L1 between a section connected to the bypass line BL2 and the first mixer 1. The valve V4 is communicatively connected to the controller 90 by means of a wire or wirelessly and is controlled by the controller 90. The controller 90 adjusts the flow rate of the ammonia supplied to the first mixer 1 by controlling the opening degree of the valve V4.

[0073] A valve V5 is provided in the bypass line BL2. The valve V5 is connected to the controller 90 via a wire or wirelessly and is controlled by the controller 90. The controller 90 adjusts the flow rate of the ammonia supplied to the third mixer 4 by controlling the opening degree of the valve V5.

[0074] 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 through the fuel supply line L1 and is supplied to the burners B as fuel.

[0075] For example, the controller 90 can control valve V4 to adjust the flow rate of the ammonia supplied from fuel supply line L1 to the first mixer 1, i.e., the flow rate of the ammonia supplied to reactor 2, so that the majority of the ammonia in the mixed gas supplied to reactor 2 is used by reaction (2), which is the exothermic reaction. The controller 90 can also control valve V5 if necessary.

[0076] For example, if reactor 2 needs to heat the mixed gas more, control unit 90 can increase the flow rate of the ammonia supplied to reactor 2 from fuel supply line L1. Conversely, if reactor 2 overheats the mixed gas, control unit 90 can, for example, decrease the flow rate of the oxidizer supplied to reactor 2 from fuel supply line L1.

[0077] The ammonia required for combustion in burners B is supplied from fuel line L1 to the third mixer 4 via bypass line BL2 and mixed with the heated mixed gas in the third mixer 4. Control unit 90 operates valve V5 to adjust the amount of ammonia supplied from fuel line L1 to bypass line BL2, i.e., the amount of ammonia supplied to the third mixer 4. Control unit 90 can also control valve V4 if necessary.

[0078] For example, if burners B require more ammonia for combustion, control 90 can increase the flow rate of ammonia supplied from fuel supply line L1 to the third mixer 4. Conversely, if the amount of ammonia supplied to burners B is excessive, control 90 can decrease the flow rate of ammonia supplied from fuel supply line L1 to the third mixer 4.

[0079] As in the first embodiment, the control unit 90 can also control at least one of the valves V4 and V5 to adjust the flow rate of the ammonia supplied to the reactor 2 and the flow rate of the ammonia supplied to the third mixer 4, so that the temperature of the mixed gas, measured by the temperature sensor S2, is below the limit (e.g. 400 °C).

[0080] The fuel preheater 10A, as described above, generally has the same effects as the fuel preheater 10 of the first embodiment. In addition, the fuel preheater 10A includes the third mixer 4, which is provided downstream of the reactor 2 in the fuel supply line L1. The third mixer 4 is connected to the fuel supply line L1 upstream of the first mixer 1 via the bypass line BL2 and mixes the mixed gas supplied by the reactor 2 with the ammonia supplied by the bypass line BL2. According to this design, the amount of ammonia supplied from the fuel supply line L1 to the reactor 2 can be adjusted more precisely.

[0081] Furthermore, the fuel preheater 10A comprises the valve V4, which is located upstream of the first mixer 1 in the fuel supply line L1 and adjusts the flow rate of the ammonia supplied to the first mixer 1; the temperature sensor S2, which is located downstream of the reactor 2 in the fuel supply line L1 and measures the temperature of the mixed gas; and the controller 90, which is communicatively connected to the valve V4 and the temperature sensor S2. The controller 90 stores the predetermined limit value associated with the temperature at which the material forming the fuel supply line L1 begins to nitrate. The controller 90 controls the valve V4 to adjust the flow rate of the ammonia supplied to the first mixer 1 so that the temperature of the mixed gas, as measured by the temperature sensor S2, remains below the limit value.According to such a design, embrittlement of the fuel supply line L1 due to nitriding can be inhibited.

[0082] Fig. Figure 3 is a schematic diagram of the combustion plant 100, which includes a fuel preheater 10B according to a third embodiment. The fuel preheater 10B differs from the fuel preheater 10 of the first embodiment in that it does not include the bypass line BL1 and the second mixer 3. With respect to other configurations, the fuel preheater 10B can be the same as the fuel preheater 10.

[0083] In the present embodiment, each burner B of the combustion system 100 is a diffusion combustion system. Each burner B is supplied with air necessary for diffusion combustion. The combustion system 100 may include components not shown, such as an air register and a damper for adjusting the amount of air to each burner B. It should be noted that in Fig. 3 Air only for the top burner B is shown.

[0084] For example, the control unit 90 controls the valve V1 to adjust the amount of oxidizer supplied from the oxidizer supply line L2 through the first mixer 1 to the reactor 2, so that most of the oxidizer in the mixed gas supplied to the reactor 2 is used by reaction (2), which is the exothermic reaction.

[0085] As in the first embodiment, the control unit 90 also controls the valve V1 to adjust the flow rate of the oxidizer supplied to the reactor 2, so that the temperature of the mixed gas, measured by the temperature sensor S2, is below the limit (e.g. 400 °C).

[0086] The fuel preheater 10B as described above generally has the same effects as the fuel preheater 10 of the first embodiment.

[0087] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, the present disclosure is not limited thereto. It is obvious that a person skilled in the art could conceive of various examples of modifications or variations within the scope of the claims which would also be understood as belonging to the technical scope of the present disclosure. Furthermore, the processes of the method of the above embodiments need not be carried out in the order given above and may be carried out in a different order, provided there is no technical contradiction.

[0088] The present disclosure may promote the use of ammonia to reduce CO2 emissions, thus contributing, for example, to Sustainable Development Goals (SDGs), Goal 7 “Ensure access to affordable, reliable, sustainable and modern energy” and Goal 13 “Take urgent action to combat climate change and its impacts”. Reference symbol list 1 first mixer 2 reactors 3 second mixer 4 third mixer 10 fuel preheaters 10A Fuel preheater 10B Fuel preheater 90 Control 100 incineration plant B Brenner BL1 Bypass Line (First Bypass Line) BL2 Bypass Line (Second Bypass Line) H Heating system 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) QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023 - 097818

[0001] JP 2019-511696 A

[0004] JP 2019-529847 A

[0004] JP H11-509307 A

[0004]

Claims

[1] Fuel preheater which features: a first mixer provided in a fuel supply line connected to a combustion plant that burns fuel comprising ammonia, the fuel supply line supplying ammonia to the first mixer, the first mixer being connected to an oxidizer supply line supplying an oxidizer, the first mixer mixing the ammonia flowing in the fuel supply line with the oxidizer from the oxidizer supply line to produce a mixed gas; and a reactor provided downstream of the first mixer in the fuel supply line, the reactor comprising a catalyst which promotes a reaction of ammonia and which causes an exothermic reaction, wherein the catalyst causes the exothermic reaction with at least a part of the ammonia in the mixed gas supplied by the first mixer and heats the mixed gas. [2] Fuel preheater according to claim 1, comprising: a second mixer provided downstream of the reactor in the fuel supply line, wherein the second mixer is connected to the oxidizer supply line by a first bypass line and mixes the mixed gas supplied from the reactor with the oxidizer supplied from the first bypass line. [3] Fuel preheater according to claim 1 or 2, comprising: a first valve provided in the oxidizer supply line that adjusts the flow rate of the oxidizer supplied to the first mixer; a temperature sensor, which is provided downstream of the reactor in the fuel supply line and measures the temperature of the mixed gas; and a controller that is communicatively connected to the first valve and the temperature sensor, wherein The controller stores a predetermined limit value associated with a temperature at which a material forming the fuel supply line begins to nitrate, and The control system controls the first valve to adjust the flow rate of the oxidizer supplied to the first mixer, ensuring that the temperature of the mixed gas measured by the temperature sensor is below the limit. [4] Fuel preheater according to claim 1, wherein the reactor comprises a heating device for heating the catalyst and the heating device comprises a heater. [5] Fuel preheater according to claim 1, wherein the reactor comprises a heating device for heating the catalyst and the heating device comprises a first heat exchanger which heats the catalyst by means of an exhaust gas from the combustion plant. [6] Fuel preheater according to claim 1, wherein the reactor comprises a heating device for heating the catalyst and the heating device comprises a second heat exchanger which heats the catalyst by means of steam taken from the combustion plant. [7] Fuel preheater according to claim 1, comprising: a third mixer provided downstream of the reactor in the fuel supply line, wherein the third mixer is connected to a position upstream of the first mixer in the fuel supply line by a second bypass line and mixes the mixed gas supplied from the reactor with the ammonia supplied from the second bypass line. [8] Fuel preheater according to claim 1 or 7, comprising: a second valve, which is provided upstream of the first mixer in the fuel supply line and adjusts the flow rate of the ammonia supplied to the first mixer; a temperature sensor, which is provided downstream of the reactor in the fuel supply line and measures the temperature of the mixed gas; and a control unit that is communicatively connected to the second valve and the temperature sensor, wherein The controller stores a predetermined limit value associated with a temperature at which a material forming the fuel supply line begins to nitrate, and The control unit regulates the second valve to adjust the flow rate of the ammonia supplied to the first mixer, so that the temperature of the mixed gas measured by the temperature sensor is lower than the limit value. [9] Fuel preheater according to claim 1, wherein the fuel preheater supplies the mixed gas to a plurality of burners in the combustion plant. [10] Fuel preheater according to claim 1, wherein the exothermic reaction at the catalyst of the reactor is a catalytic combustion. [11] Method of installing a fuel preheater in a combustion plant, wherein the method comprises: Preparing a first mixer designed to mix ammonia and an oxidizer; Preparing a reactor that includes a catalyst which causes an exothermic reaction with ammonia; Installing the first mixer in a fuel supply line connected to a combustion plant that burns fuel comprising ammonia, wherein the fuel supply line supplies ammonia to the first mixer; Connecting an oxidizer supply line, which supplies an oxidizer, to the first mixer, the first mixer mixing the ammonia flowing in the fuel supply line with the oxidizer from the oxidizer supply line to produce a mixed gas; and Installing the reactor downstream of the first mixer in the fuel supply line, wherein the catalyst causes the exothermic reaction with at least some of the ammonia in the mixed gas supplied by the first mixer and heats the mixed gas.

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