Combustion system and steam supply equipment

Abstract

To provide a combustion device that is CO2 free and can stably generate steam using ammonia, in general-purpose applications such as steam boilers.SOLUTION: A combustion system comprises: an ammonia decomposition gas generation device that decomposes ammonia and generates gas using at least one of gas generated by decomposing ammonia or ammonia as fuel; and a combustion device having a combustion furnace with a room temperature of less than 1000°C or a combustion device of a boiler with a thermal output of 22000 kW or less, which uses gas generated from the ammonia decomposition gas generation device as fuel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a combustion system and Steam supply equipment Preparation Regarding. [Background technology]

[0002] Patent Document 1 discloses an ammonia decomposition facility comprising: a heat transfer line through which a heat transfer medium heated by heat generated by a gas turbine flows; an ammonia supply line through which ammonia flows; an ammonia decomposition device connected to the heat transfer line and the ammonia supply line, which uses the heat of the heat transfer medium from the heat transfer line to thermally decompose the ammonia from the ammonia supply line to produce a decomposition gas containing hydrogen, nitrogen, and residual ammonia; an ammonia removal device that removes the residual ammonia contained in the decomposition gas from the ammonia decomposition device; and a treated gas supply line that guides the treated gas, which is the decomposition gas from which the residual ammonia has been removed by the ammonia removal device, to a gas utilization target. Furthermore, Patent Document 1 includes the ammonia decomposition equipment and the gas turbine, The gas turbine disclosed comprises an air compressor that compresses air to generate compressed air, a combustor that burns fuel in the compressed air to generate combustion gas, and a turbine driven by the combustion gas. The treated gas supply line guides the treated gas to the combustor, with the combustor being the target of the gas utilization. Patent Document 2 describes a hydrogen-containing fuel supply system for a power plant including a steam turbine, comprising a first ammonia decomposition device for decomposing ammonia to produce nitrogen and hydrogen, A hydrogen-containing fuel supply system is disclosed, comprising: a fuel supply line connected to the combustion unit of the power plant and the first ammonia decomposition unit for supplying hydrogen-containing fuel, including the hydrogen produced in the first ammonia decomposition unit, to the combustion unit; and an extraction steam line connected to the steam turbine and the first ammonia decomposition unit for guiding extracted steam from the steam turbine, which is driven by steam heated by heat exchange with the combustion gas produced in the combustion unit, to the first ammonia decomposition unit, wherein the first ammonia decomposition unit is configured to decompose ammonia using the extracted steam as a heat source. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-147481 [Patent Document 2] Japanese Patent Publication No. 2018-95512 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In the context of a society demanding decarbonization and carbon neutrality, there is a growing need for carbon dioxide (CO2)-free steam supply in the future. Ammonia is attracting attention because it does not emit CO2 when burned, but it has poor flammability compared to hydrocarbon fuels, and it is difficult to burn it well in environments with low combustion chamber temperatures. For example, when using ammonia as fuel for steam boilers, good combustion can only be achieved in special applications where the combustion chamber temperature can be kept high at all times, such as gas turbines. While the use of gas containing hydrogen and nitrogen generated from the thermal decomposition of ammonia in electric heating furnaces has been implemented, the energy required for ammonia thermal decomposition is supplied from fossil fuels such as electric heaters, oil heaters, natural gas, and propane, and the fact that the thermal decomposition is not CO2-free has been a problem. Furthermore, in furnaces other than the aforementioned electric heating furnaces, the gas produced by the decomposition of ammonia has been used as the atmosphere gas of the furnace, but because there are fossil fuels that are more combustible and cheaper than ammonia, the gas produced by the decomposition of ammonia has not been used as fuel. The present invention aims to provide a combustion device that can stably generate steam in a CO2-free manner, without using fossil fuels such as petroleum, natural gas, or propane, by using a gas produced by the decomposition of ammonia as fuel, for general-purpose applications such as steam boilers. [Means for solving the problem]

[0005] The invention described in claim 1 relates to a gas produced by the decomposition of ammonia, or ammonia, at least one of the two. Burner The system comprises an ammonia decomposition gas generator that uses ammonia as fuel to decompose and produce gas, and a combustion device having a combustion furnace at a room temperature of less than 1000°C or a boiler with a thermal output of 22000kW or less that uses the gas produced from the ammonia decomposition gas generator as fuel. The fuel in the combustion device contains ammonia. It is a combustion system. The invention described in claim 2 is the combustion system according to claim 1, wherein the combustion apparatus is a steam boiler or a hot water boiler, and is supplied with steam or hot water. 。 request request 3 The invention described herein is that the ammonia in the fuel of the combustion device is either residual or supplied during the ammonia decomposition, claim 1 This is the combustion system described. Claim 4 The invention described herein relates to the ammonia decomposition gas generator which decomposes gaseous ammonia obtained by vaporizing liquid ammonia, and recovers the waste heat of the ammonia decomposition gas generator for use in vaporizing the liquid ammonia, as described in claims 1 to 3The combustion system is one of the following:

[0006] The invention described in claim 5 is a steam supply system comprising: a tank for storing liquid ammonia; a vaporizer for vaporizing the liquid ammonia supplied from the tank; an ammonia decomposition gas generator that uses at least one of a gas produced by decomposing ammonia or ammonia itself as fuel for a burner and decomposes the gaseous ammonia produced in the vaporizer; a steam boiler that provides steam using the gas produced from the ammonia decomposition gas generator as fuel, wherein the fuel contains ammonia; and a waste heat recovery device that recovers waste heat from the ammonia decomposition gas generator and supplies it to the vaporizer. The invention described in claim 6 is a steam supply system according to claim 5, wherein the ammonia in the fuel of the steam boiler is either residual or supplied during the ammonia decomposition process. ru. [Effects of the Invention]

[0007] According to the invention of claim 1, even when using ammonia, which burns more slowly than petrochemical raw materials, as a fuel source, stable operation is possible in a combustion device having a combustion furnace at a room temperature of less than 1000°C, or in a combustion device of a boiler with a thermal output of 22000kW or less, and an overall CO2-free combustion system can be provided. According to the invention of claim 2, even when using ammonia, which has a slow combustion rate, as a fuel source, a combustion system that enables stable operation can be provided in a general-purpose steam boiler or hot water boiler. According to the inventions of claims 3 and 4, the energy supplied to the ammonia decomposition gas generator can be reduced compared to the case where the fuel of the combustion device does not contain ammonia. According to the invention of claim 5, the energy supplied to the system can be reduced compared to a case where the waste heat of the ammonia decomposition gas generator is not recovered.

[0008] According to the invention of claim 6, even when ammonia with a slow combustion rate is used as a fuel source, a steam boiler for general use can be stably operated and can provide steam without CO2. According to the inventions of claims 7 and 8, the energy supplied to the ammonia decomposition gas generator can be reduced as compared with the case where ammonia is not contained in the fuel of the steam boiler. According to the invention of claim 9, even when ammonia with a slow combustion rate compared to fossil raw materials is used as a fuel source, stable operation is possible in a combustion device having a combustion furnace that is not at a high temperature and is less than 1000 °C at room temperature or a combustion device of a boiler with a thermal output of 22000 kW or less, and a CO2-free combustion device can be provided as a whole. According to the invention of claim 10, the energy supplied to the system can be reduced as compared with the case where the fuel of the steam boiler does not contain ammonia. <于

Brief Description of the Drawings

[0009] [Figure 1] It is a flowchart showing an overview of a combustion system in a first embodiment according to the present invention. [Figure 2] It is a flowchart showing an overview of a combustion system in a second embodiment according to the present invention. [Figure 3] It is a conceptual diagram of an example of an ammonia decomposition gas generator used in the present invention.

Modes for Carrying Out the Invention

[0010] Embodiments of the combustion system, steam supply facility, and combustion device of the present invention will be described with reference to FIGS. 1 to 3. These descriptions and the like are illustrative of the embodiments and do not limit the scope of the invention. In the present disclosure, the description of "〇〇 or more and 〇〇 or less" or "〇〇 to 〇〇" representing a numerical range means a numerical range including the described upper and lower limits, unless otherwise specified.

[0011] "First Embodiment" As shown in Figure 1, the combustion system of this embodiment comprises a tank 10 for storing ammonia, an ammonia decomposition gas generation facility 20, an initial startup facility 30, and a combustion facility 40 such as a steam boiler. Ammonia, which serves as the fuel source for the entire combustion system, is typically transported as liquid ammonia by tank trucks or other means via ship, land, rail, etc., or by pipeline from other locations or facilities (not shown), and stored in a liquid ammonia storage tank 10. Ammonia has a boiling point of -33°C at atmospheric pressure and liquefies at 8.5 atmospheres at 20°C, so it is stored as liquid ammonia at a temperature close to its boiling point. Hydrogen, which is also a CO2-free raw material, has an extremely low boiling point of -252.9°C at atmospheric pressure, so compared to liquid hydrogen, the transportation cost of liquid ammonia is very low, and storage is also easy.

[0012] (Ammonia decomposition gas generation equipment) The ammonia decomposition gas generation equipment 20 is equipment that uses liquid ammonia as a raw material, decomposes the ammonia, and produces ammonia decomposition gas. The ammonia decomposition gas generation equipment 20 comprises an ammonia decomposition gas generator 21 that decomposes ammonia to produce gas, an ammonia vaporizer 23 that vaporizes ammonia to produce ammonia gas, and a waste heat boiler 25 that recovers waste heat from the ammonia decomposition gas generator 21. The liquid ammonia stored in tank 10 is supplied to ammonia vaporizer 23 via ammonia supply line 101, where it is converted into ammonia gas. The energy required for vaporization of liquid ammonia is mainly supplied from hot water supplied via hot water supply line 502 from waste heat recovery means such as waste heat boiler 25 (described later), and from heat exchange with liquid ammonia. Any remaining energy is supplied from power sources, boilers, etc.

[0013] Next, the obtained ammonia gas is supplied to the ammonia decomposition gas generator 21 via the ammonia supply line 102. In the ammonia decomposition gas generator 21, nitrogen and hydrogen are produced from the raw material ammonia by the decomposition reaction shown in the chemical formula below. Hereinafter, the gas produced by the decomposition of ammonia will be referred to as "ammonia decomposition gas". 2NH3 → N2 + 3H2 - 980 (kcal / Nm) 3 )···(1) As shown in equation (1), the ammonia decomposition reaction is an endothermic reaction, and is usually a thermal decomposition reaction. Therefore, in order to stably continue the decomposition reaction, the combustion chamber of the ammonia decomposition gas generator 21 needs to be kept at a high temperature by a burner 22 or the like. To achieve the required high temperature, the fuel supplied to the burner 22 in the ammonia decomposition gas generator 21 is a portion of the ammonia decomposition gas produced in the ammonia decomposition gas generator 21, supplied from the supply line 202. However, since no ammonia decomposition gas is produced before the ammonia decomposition gas generator 21 starts operation, ammonia decomposition gas separately produced in the initial start-up equipment 30 is used as fuel.

[0014] As mentioned above, ammonia decomposition gas contains at least nitrogen and hydrogen. It may also contain other substances such as water. In this embodiment, it is possible to leave unreacted ammonia in the ammonia decomposition gas. By leaving ammonia after the reaction and using it as fuel for the steam boiler 41 in the combustion equipment 40 described later, the energy required for ammonia decomposition (fuel supplied, etc.) can be reduced. Furthermore, it is also possible to add ammonia to the ammonia decomposition gas from outside the apparatus as fuel for the steam boiler 41, or to add ammonia to the unreacted residual ammonia from outside the apparatus, and in either case, the energy required for ammonia decomposition can be reduced.

[0015] Conventionally, since burning ammonia tends to generate nitrogen oxides, it has been avoided to leave ammonia in the combustion gas. For example, when supplying ammonia decomposition gas to a power generation turbine, the goal has been to reduce the proportion of ammonia remaining in the decomposition gas, and if ammonia remains, it has been removed (see Patent Documents 1 and 2). However, in the combustion apparatus of this embodiment (such as the steam boiler 41 in the combustion equipment 40), if a technology to suppress the generation of nitrogen oxides is employed, it is possible to intentionally leave ammonia in the ammonia decomposition gas supplied from the ammonia decomposition gas generator 21 to the steam boiler 41 through the supply line. Methods for reducing nitrogen oxide generation caused by residual ammonia in a combustion device are not particularly limited, but include two-stage combustion and low NO generation. X One example is the burner method, with the two-stage combustion method being particularly preferred. Two-stage combustion is a combustion method that reduces nitrogen oxides in the combustion exhaust gas by designing the structure of the combustion burner to supply combustion air in two stages to the fuel supply and then burning the fuel. Nitrogen oxides generated by the combustion of fuel include nitrogen oxides (FuelNOx) that are generated when nitrogen in the fuel is oxidized. X ) and nitrogen oxides (Thermal NO) are generated when nitrogen in the air supplied for combustion is oxidized. X ) and the nitrogen oxides generated in this embodiment are FuelNO X This is the main focus. FuelNO X Thermal NO is produced in larger quantities as the oxygen concentration in the combustion region increases. X The higher the combustion temperature, the higher the oxygen concentration in the combustion region, and the longer the residence time of the combustion gas in the high-temperature region, the more of this substance is generated. In the two-stage combustion method, combustion air is supplied in two stages. In the first stage, the amount of air supplied is limited to about 80 - 90% of the theoretical air volume to cause combustion with insufficient oxygen concentration. Then, in the immediately following second stage, the insufficient air is supplemented and supplied, and complete combustion is achieved with an overall excess air ratio. By forming a reducing zone in the first stage, it becomes possible to lower the flame temperature and the oxygen concentration, thereby suppressing the generation of nitrogen oxides. Specifically, two-stage combustion can be implemented by attaching a secondary air nozzle to the burner, attaching a two-stage combustion port to the front wall or side wall of the boiler, adjusting the burner shape, adjusting the combustion device, etc. For example, in the case of an experiment where ammonia is burned, the nitrogen oxides generated in normal single-stage combustion were 1300 ppm, but when the two-stage combustion method was implemented using the same combustion device, it was confirmed that the nitrogen oxide concentration could be reduced to 95 ppm by adjusting the amount of air supplied. Low NO X The burner method is a nitrogen oxide reduction method that incorporates one or a combination of nitrogen oxide reduction methods such as oxygen concentration reduction, flame temperature reduction, and shortening of the gas residence time in the high-temperature region into the burner. As such burners, low NO X burners such as staged combustion type, rapid combustion type, divided flame type, self-recirculation type, etc. can be used. By including ammonia in the fuel of a combustion device such as a steam boiler 41, the total energy amount of the entire combustion system, such as the fuel supplied to the burner 22 of the ammonia decomposition gas generator 21, can be reduced, leading to cost reduction. However, since ammonia has a slower combustion rate compared to hydrogen, which is the main fuel in the ammonia decomposition gas, combustion becomes difficult when the amount of residual ammonia is excessive. For combustion property adjustment, either ammonia or hydrogen, or both, may be supplied from outside the system. The amount of residual ammonia to be left in the ammonia decomposition gas when supplied as fuel to the steam boiler 41, and the amount of ammonia, hydrogen, etc. supplied from outside the system, should preferably be determined by comprehensively considering the flammability of the ammonia decomposition gas, the energy requirements of the entire combustion system, costs, etc. In the ammonia decomposition gas, ammonia can be substantially completely decomposed, and it is also possible to leave some ammonia behind. The residual ammonia concentration can be adjusted by the ammonia decomposition conditions in the ammonia decomposition gas generator 21. Adjustment by the ammonia decomposition temperature is particularly preferred, and by lowering the decomposition temperature, ammonia can be left behind. The ammonia concentration in the ammonia decomposition gas supplied as fuel to the steam boiler 41 is preferably 60% by volume or less, and more preferably 50% by volume or less.

[0016] Since the exhaust gas 501 discharged from the combustion chamber of the ammonia decomposition gas generator 21 is at a high temperature of about 500°C to 600°C, it is preferable to recover the waste heat using a waste heat recovery means such as a waste heat boiler 25. In this embodiment, the exhaust gas 501 is used as a heat source to obtain hot water heated from the waste heat boiler 25, and this hot water is supplied to the ammonia vaporizer 23 by a hot water supply line 502. This allows the recovered waste heat to be used for vaporizing liquid ammonia, and reduces the amount of energy supplied from outside during ammonia vaporization.

[0017] (Initial startup equipment) Here, the initial startup equipment 30 will be described. As described above, the initial startup equipment 30 is equipment for providing fuel for the gaseous ammonia decomposition reaction carried out in the ammonia decomposition gas generator 21 before the ammonia decomposition gas generator 21 starts operation. The initial startup equipment 30 comprises a starting ammonia vaporizer 33 and a starting ammonia decomposition gas generator 31 (hereinafter abbreviated as "starting gas generator 31"). In the initial startup equipment 30, before the ammonia decomposition gas generator 21 starts operation, a portion of the liquid ammonia supplied from the tank 10 is separated and supplied via the supply line 301 to a startup ammonia vaporizer 33, which is provided separately from the ammonia vaporizer 23. In the startup ammonia vaporizer 33, the liquid ammonia is converted to ammonia gas through heat exchange with the atmosphere, and ammonia decomposition gas containing at least nitrogen and hydrogen is produced in the startup ammonia decomposition gas generator 31, similar to the ammonia decomposition gas generator 21. Although there are no restrictions on the fuel used for the startup ammonia decomposition gas generator 31, electric heating is usually used. This is because the amount of ammonia decomposed in the startup gas generator 31 is small compared to the ammonia used as raw material for the ammonia decomposition gas generator 21, and the operating time of the startup equipment is limited to the short period until the ammonia decomposition gas generator 21 starts operation. The ammonia decomposition gas generated by the startup ammonia decomposition gas generator 31 is supplied to the burner 22 of the ammonia decomposition gas generator 21 via the supply line 303, and serves as fuel for the ammonia decomposition reaction in the ammonia decomposition gas generator 21. Once the ammonia decomposition gas generator 21 starts operating and ammonia decomposition gas is generated, the startup ammonia decomposition gas generator 31 has completed its role and is shut down. After that, a portion of the ammonia decomposition gas generated by the ammonia decomposition gas generator 21 is supplied to the burner 22 via the supply line 202, and serves as fuel for the decomposition reaction of the ammonia decomposition gas generator 21 itself.

[0018] (Combustion equipment) The combustion equipment 40 includes a combustion device having a combustion furnace with a room temperature of less than 1000°C, or a combustion device of a boiler with a thermal output of 22000kW or less, which uses ammonia decomposition gas produced by the ammonia decomposition gas generator 21 as fuel. Because ammonia has poor flammability, using ammonia as fuel has been limited to special applications such as gas turbines with a combustion furnace room temperature of 1000°C or higher, or power generation boilers with a thermal output of 22000kW or more. In contrast, the present invention enables stable combustion even in combustion devices with a combustion furnace at a room temperature of less than 1000°C, or in a combustion device of a boiler with a thermal output of 22000kW or less, by decomposing ammonia and using ammonia decomposition gas, which mainly consists of hydrogen, as fuel. In this invention, a combustion device having a combustion furnace with a room temperature of less than 1000°C refers to a combustion device having a combustion chamber where the minimum temperature inside the combustion chamber is less than 1000°C. Furthermore, a combustion device for a boiler with a thermal output of 22000kW or less refers to a boiler with a thermal output of 22000kW or less. In this invention, it is sufficient for the boiler to meet at least one of the following conditions: a combustion chamber temperature of less than 1000°C or a thermal output of 22000kW or less. In the case of a boiler with a small combustion chamber, such as a normal steam boiler, the combustion chamber is almost entirely filled with flames, making it difficult to determine the temperature inside the combustion chamber. Therefore, the determination of whether or not the device meets the criteria is based on the thermal output of the boiler. Thermal output is the output per combustion device, and when multiple combustion devices are used in combination, the determination is based on the combustion chamber temperature or thermal output of each combustion device. Preferably, the thermal output is 11000kW or less, more preferably 5000kW or less, and even more preferably 2000kW or less. Boilers that meet these conditions are generally called "general-purpose boilers," and in the case of steam boilers, those with an evaporation rate of 30 tons / hour or less are typical. These boilers are small compared to other boilers, and the applicable equipment can be transported and installed at the point of use. In contrast, large boilers outside the scope of the present invention (equipment with a thermal output exceeding 22,000 kW), such as power generation boilers, are typical examples, but when supplying CO2-free steam, fuel supply equipment such as the ammonia decomposition gas generation equipment 20 must be newly designed, manufactured, and installed separately. In the present invention, because the combustion device is small, other equipment such as the ammonia decomposition gas generation equipment 20 and the initial startup equipment 30 in this embodiment can be easily repurposed as is or with minor modifications from general-purpose equipment for other uses (metal processing, etc.). Furthermore, because it is general-purpose and relatively small equipment, it is easy to operate this embodiment using only CO2-free ammonia as the raw material for the entire embodiment, without using fossil fuels in combination. On the other hand, combustion devices outside the scope of the present invention (devices with a minimum combustion chamber temperature of 1000°C or higher and a thermal output exceeding 22000kW) often require the combined use of fossil fuels as well as ammonia as power generation fuel (see Patent Document 2), making it difficult to achieve the objective of the present invention, which is to provide a CO2-free combustion device capable of stably generating steam. The combustion device is not limited to those that satisfy the above conditions, and examples include general-purpose boilers such as steam boilers, hot water boilers, and heat transfer fluid boilers, as well as aluminum heat treatment furnaces, drying furnaces, gas engines, and gas turbines. Steam boilers and hot water boilers are particularly suitable for implementing the present invention.

[0019] In this embodiment shown in Figure 1, the combustion equipment 40 includes a steam boiler 41 that supplies room temperature water in exchange for steam, and a feedwater meter 42. The fuel used to burn the steam boiler 41 is the ammonia decomposition gas produced by the ammonia decomposition gas generator 21 described above, which mainly consists of hydrogen and nitrogen, and may also contain inert gases such as water. In addition, as described above, a predetermined amount of unreacted ammonia is left behind, and if necessary, at least one of ammonia or hydrogen may be added from outside the system to adjust the combustibility. This ammonia decomposition gas is supplied from the ammonia decomposition gas generator 21 to the steam boiler 41 via the supply line 201. Meanwhile, the water used as the raw material for steam is supplied from supply line 401 as suitable water source such as industrial water or tap water, and is supplied to the steam boiler 41 from supply line 402 via feedwater meter 42. In the steam boiler 41, the ammonia decomposition gas is converted into steam by the combustion heat, and the steam is sent from supply line 403 to the steam user (not shown).

[0020] "Second Embodiment" The combustion system of the second embodiment will be described with reference to Figure 2. Numbers that are the same as in Figure 1 have the same meaning as in Figure 1. In this system, as shown in Figure 2, similar to Figure 1, it includes an ammonia storage tank 10, an ammonia decomposition gas generation facility 20, and combustion equipment 40 such as a steam boiler, and instead of the initial startup equipment 30 in Figure 1, it includes an ammonia supply facility 60 for the burner. This section will focus on explaining the differences from the first embodiment. The ammonia supply equipment 60 for the burner includes an ammonia vaporizer 63 for the burner. The ammonia vaporizer 63 receives a portion of the liquid ammonia stored in the tank 10 from the supply line 601, vaporizes it into gaseous ammonia through heat exchange with air, and supplies it to the burner 22 via the supply line 602 as fuel for the ammonia decomposition gas generator 21. In the second embodiment, unlike the first embodiment, gaseous ammonia supplied from the burner ammonia supply equipment 60 through the supply line 602 is used as fuel for ammonia decomposition carried out in the ammonia decomposition gas generator 21. By using gaseous ammonia as fuel, the gaseous ammonia fuel can be obtained as needed by vaporizing liquid ammonia, so unlike the first embodiment, equipment corresponding to the initial startup equipment 30 in Figure 1 is not required.

[0021] The ammonia decomposition gas generation equipment 20, similar to the first embodiment, includes an ammonia decomposition gas generator 21 that decomposes ammonia to produce gas, an ammonia vaporizer 23 that vaporizes ammonia to produce ammonia gas, and a waste heat boiler 25 that recovers waste heat from the ammonia decomposition gas generator 21. The ammonia decomposition gas contains at least nitrogen and hydrogen, and may also contain water and other substances. In this embodiment as well, it is preferable to leave unreacted ammonia in the ammonia decomposition gas supplied to the combustion equipment 40. Unlike the first embodiment, the fuel used in the ammonia decomposition gas generator 21 is gaseous ammonia, not ammonia decomposition gas. Therefore, unlike the first embodiment, gaseous ammonia is supplied from the burner ammonia vaporizer 63, and the ammonia decomposition gas generated by the ammonia decomposition gas generator 21 is supplied entirely to the steam boiler 41. The combustion equipment 40 of the second embodiment shown in Figure 2 is the same as the combustion equipment 40 of the first embodiment. Specifically, the combustion equipment 40 includes a combustion device having a combustion furnace with a room temperature of less than 1000°C, or a boiler with a thermal output of 22000kW or more, which uses ammonia decomposition gas generated by the ammonia decomposition gas generator 21 as fuel. The combustion equipment 40 includes a steam boiler 41 that converts room temperature water into steam and supplies it, and a feedwater meter 42. The description of the combustion equipment 40 is the same as that of the first embodiment shown in Figure 1, so it is omitted here.

[0022] "Ammonia decomposition gas generator" One embodiment of the ammonia decomposition gas generator 21 will be described with reference to Figure 3. Figure 3 is a conceptual diagram of the ammonia decomposition gas generator 21, showing an ammonia decomposition gas generator 21 in a form similar to the second embodiment. The same numbers as in Figures 1 and 2 have the same meaning. In the ammonia vaporizer 23, liquid ammonia undergoes heat exchange with hot water from the waste heat boiler 25 (described later) to become gaseous ammonia. A portion of the gaseous ammonia is supplied to the burner 22 via the supply line 601 as fuel for the ammonia decomposition gas generator 21. Unlike the second embodiment, the embodiment in Figure 3 does not have a burner ammonia vaporizer 63, and the ammonia vaporizer 23 performs the functions of both the ammonia vaporizer 23 and the burner ammonia vaporizer 63 in Figure 2. The remaining gaseous ammonia is the main raw material for the decomposition gas and is supplied from the ammonia supply line 102 to the heat exchanger 26. In the heat exchanger 26, the gaseous ammonia exchanges heat with the ammonia decomposition gas sent from the reactor via the supply line 201 and is heated to about 100°C. Further preheating of the gaseous ammonia to about 500°C in the ammonia preheater 27, it comes into contact with the catalyst 28 in the reaction chamber 81, and a decomposition reaction occurs. The reaction catalyst is not limited as long as it exhibits a catalytic effect for ammonia decomposition, but examples include noble metals such as ruthenium, and transition metals such as nickel, cobalt, and iron, with ruthenium or nickel being preferred. Since the decomposition temperature of gaseous ammonia is about 500°C, it is preferable to raise the reaction chamber temperature to about 900°C using the burner 22. Lowering the reaction temperature of the ammonia to be decomposed and leaving some ammonia after the reaction, as described above, is also a preferred configuration. It is preferable to use fire-resistant materials such as bricks that can withstand the reaction temperature for the reaction chamber walls of the reaction chamber 81 where the ammonia decomposition reaction takes place.

[0023] The ammonia decomposition gas after the reaction is cooled from approximately 500°C (the decomposition temperature) to approximately 100°C by heat exchange with gaseous ammonia in the aforementioned heat exchanger 26. Then, it is cooled to room temperature by the cooling water in the cooler 29 and supplied to the steam boiler 41 (not shown in Figure 3) via the supply line 201. The exhaust gas at 500°C to 600°C discharged from the reaction chamber 81 is sequentially sent via exhaust gas discharge lines 503, 504, and 505 to the steam boiler or air preheater 82, waste heat boiler 25, and exclusion device 83, where it is discharged from discharge line 506 at 200°C to 300°C. In the steam boiler or air preheater 82, the exhaust gas at approximately 500°C to 600°C is used for air preheating, steam boiling, etc. In the waste heat boiler 25, heat is recovered using hot water circulated in the hot water supply line 502 between it and the ammonia vaporizer 23 mentioned above, and the exclusion device 83 removes any remaining ammonia in the exhaust gas using a scrubber or the like.

[0024] The present invention is not limited to the embodiments described above, and other embodiments are possible within the spirit of the present invention. For example, it is possible to use both ammonia decomposition gas and ammonia as fuel for the ammonia decomposition gas generator 21. Furthermore, it is possible to perform ammonia decomposition without a catalyst. [Explanation of Symbols]

[0025] 10...Tank, 20...Ammonia decomposition gas generation equipment, 21...Ammonia decomposition gas generator, 22...Burner, 23...Ammonia vaporizer, 25...Waste heat boiler, 27...Ammonia preheater, 28...Catalyst, 30...Initial startup equipment, 31...Startup ammonia decomposition gas generator, 33...Startup ammonia vaporizer, 40...Combustion equipment, 41...Steam boiler, 60...Ammonia supply equipment for burner, 63...Ammonia vaporizer for burner, 81...Reaction chamber

Claims

1. An ammonia decomposition gas generator that uses at least one of the gas produced by the decomposition of ammonia, or ammonia itself, as fuel for a burner, and produces gas by decomposing ammonia, A combustion device having a combustion furnace at a room temperature of less than 1000°C, or a combustion device of a boiler with a thermal output of 22000 kW or less, which uses the gas produced from the ammonia decomposition gas generator as fuel, Equipped with, The fuel in the aforementioned combustion device contains ammonia. Combustion system.

2. The combustion system according to claim 1, wherein the combustion apparatus is a steam boiler or a hot water boiler that supplies steam or hot water.

3. The ammonia in the fuel of the combustion device is either residual ammonia from the ammonia decomposition process or ammonia that was supplied. The combustion system according to claim 1.

4. The ammonia decomposition gas generator decomposes gaseous ammonia obtained by vaporizing liquid ammonia, recovers waste heat from the ammonia decomposition gas generator and uses it to vaporize the liquid ammonia. The combustion system according to any one of claims 1 to 3.

5. A tank for storing liquid ammonia, A vaporizer that vaporizes liquid ammonia supplied from the aforementioned tank, An ammonia decomposition gas generator that uses at least one of ammonia or a gas produced by the decomposition of ammonia as fuel for a burner, and decomposes the gaseous ammonia produced in the vaporizer, A steam boiler that provides steam using gas generated from the ammonia decomposition gas generator as fuel, wherein the fuel contains ammonia, A waste heat recovery device that recovers waste heat from the ammonia decomposition gas generator and supplies it to the vaporizer, A steam supply system equipped with the following features.

6. The ammonia in the fuel of the steam boiler is either residual ammonia from the ammonia decomposition process or ammonia that was supplied. The steam supply equipment according to claim 5.

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