Heat treatment facility

Abstract

To provide a heat treatment facility capable of further reducing carbon dioxide emission.SOLUTION: A heat treatment facility is a heat treatment facility for performing heat treatment on an object, and includes a heat treatment furnace into which the object is introduced, a storage unit that stores ammonia, a supply line that takes out the ammonia from the storage unit, a decomposition unit that is provided on the supply line and decomposes the ammonia into hydrogen and nitrogen, and a combustion unit that is provided in the heat treatment furnace and generates combustion gas by combusting at least hydrogen of gas supplied from the decomposition unit through the supply line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to heat treatment equipment. [Background technology]

[0002] Annealing during steelmaking and quenching and tempering of metal products require high-calorie heat. Various technologies have been proposed for using waste heat generated outside the facilities used for these types of processes. For example, Patent Document 1 listed below discloses a technology for recovering carbon dioxide gas generated within a steelworks and using it as a heat source for various purposes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6566252 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when the recovered carbon dioxide gas is used for the above-mentioned annealing process, the exhaust gas still contains carbon dioxide, which poses a problem that the achievement of the intended purpose of reducing carbon dioxide emissions is limited.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide heat treatment equipment that can further reduce carbon dioxide emissions. [Means for solving the problem]

[0006] In order to solve the above problems, the heat treatment equipment according to the present disclosure is heat treatment equipment for performing heat treatment on an object, and includes a heat treatment furnace into which the object is introduced, a storage section for storing ammonia, a supply line for extracting the ammonia from the storage section, a decomposition section provided on the supply line for decomposing the ammonia into hydrogen and nitrogen, and a combustion section provided within the heat treatment furnace for generating combustion gas by combusting at least the hydrogen of the gas supplied from the decomposition section through the supply line. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide heat treatment equipment that can further reduce carbon dioxide emissions. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a configuration of a heat treatment facility according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a heat treatment facility according to a second embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic cross-sectional view showing a modified example of the combustion section according to each embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A heat treatment facility 1 according to a first embodiment of the present disclosure will be described below with reference to Fig. 1. The heat treatment facility 1 is a facility for performing heat treatment such as annealing in a steelworks, or quenching or tempering of metal products, for example.

[0010] (Configuration of heat treatment equipment 1) As shown in FIG. 1, the heat treatment equipment 1 includes a heat treatment furnace 10, a combustion section 20, a storage section 30, a supply line 40, a decomposition section 50, an exhaust gas line 60, a chimney 70, an air line 80, a preheating section 90, a recovery section 100, an exhaust gas blower 110, and a combustion air blower 120.

[0011] (Heat treatment furnace 10) The heat treatment furnace 10 is a container that contains iron or metal products (hereinafter referred to as the target object 200) to be heat treated. A combustion section 20 is provided inside the heat treatment furnace 10. The combustion section 20 forms a flame by burning a gas, which will be described later, and uses the resulting heat to perform heat treatment such as annealing on the target object 200. The target object 200 is placed on the bottom surface of the heat treatment furnace 10 or is transported by a roller conveyor or the like, and it is desirable that multiple combustion sections 20 be provided on the upper part of the heat treatment furnace 10.

[0012] High-temperature combustion air is supplied to the combustion section 20 through an air line 80, which will be described later, together with the above gases.

[0013] (Details of combustion section 20) The combustion section 20 has a nozzle 21 and an ignition device (not shown). The nozzle 21 injects gas into the heat treatment furnace 10. The ignition device ignites the gas by emitting a spark or the like. The gas burns with combustion air to form a premixed flame or a diffusion flame, which generates high-temperature combustion gas. The heat of this combustion gas is used to heat-treat the object 200.

[0014] The temperature of the combustion gas is preferably 800°C or higher and 1200°C or lower. More preferably, this temperature is 900°C or higher and 1100°C or lower. Most preferably, the temperature of the combustion gas is 1000°C. This is the optimum temperature as the atmospheric temperature in the annealing treatment. It is also a temperature at which thermal NOx is unlikely to be generated.

[0015] (Storage section 30) The storage unit 30 is a container for storing ammonia, which is the raw material for the gas. The ammonia is stored in a liquid state. That is, the inside of the storage unit 30 may be at room temperature and pressure. The liquid ammonia in the storage unit 30 is extracted through a supply line 40.

[0016] (Disassembly section 50) The supply line 40 is a pipe connecting the storage section 30 and the combustion section 20. A decomposition section 50 is provided on the supply line 40. The decomposition section 50 produces nitrogen and hydrogen by thermally decomposing liquid ammonia through a catalytic reaction. The decomposition section 50 has a first heat exchanger 51 (heat exchanger), a decomposition section main body 52, and a second heat exchanger 53. The decomposition section 50 may further have an ARU 54 (Ammonia Recovery Unit) as necessary. These devices are arranged in this order on the supply line 40 from the storage section 30 side (upstream side) to the combustion section 20 side (downstream side).

[0017] The first heat exchanger 51 vaporizes the ammonia by exchanging heat between the liquid ammonia supplied from the storage section 30 and the heat medium. Although not shown in detail, the heat medium of the first heat exchanger 51 can be an externally supplied gas or the like, or an exhaust gas flowing through an exhaust gas line 60, which will be described later.

[0018] The decomposition unit main body 52 thermally decomposes ammonia gas through a catalytic reaction to produce nitrogen and hydrogen. That is, the decomposition unit main body 52 contains a metal catalyst such as nickel or ruthenium. When thermal energy from the exhaust gas (described later) is applied to this catalyst, the thermal decomposition of ammonia progresses.

[0019] The second heat exchanger 53 is used to lower the temperature of the gas containing nitrogen and hydrogen produced in the decomposition section main body 52. ​​A gas or liquid introduced from the outside, or room temperature air, etc., is used as a coolant for this second heat exchanger 53. The gas that has passed through the second heat exchanger 53 is separated or classified into decomposed components and unreacted components in the ARU 54, and then sent to the combustion section 20 described above via the supply line 40.

[0020] (Exhaust gas line 60) The exhaust gas line 60 is a flow path for guiding exhaust gas generated in the heat treatment furnace 10 to the outside. The exhaust gas line 60 connects the space inside the heat treatment furnace 10 with the chimney 70. The decomposition unit main body 52 is provided midway along the exhaust gas line 60. That is, the exhaust gas is supplied to the decomposition unit main body 52 as a heat source used in the catalytic reaction.

[0021] A preheating section 90 is disposed on the exhaust gas line 60 downstream of the decomposition section main body 52 (i.e., on the chimney 70 side). The preheating section 90 is a heat exchanger that exchanges heat between low-temperature air supplied through the air line 80 and high-temperature exhaust gas. That is, the preheating section 90 heats the air using the heat of the exhaust gas. The exhaust gas that passes through the preheating section 90 is in a low-temperature state and flows to the chimney 70, through which it is released into the atmosphere. An exhaust gas blower 110 is disposed on the exhaust gas line 60 between the chimney 70 and the preheating section 90. The exhaust gas on the exhaust gas line 60 is pressure-fed by this exhaust gas blower 110 in a direction from the heat treatment furnace 10 toward the chimney 70.

[0022] (Air line 80) The air line 80 is a flow path for taking out external air and supplying it to the combustion section 20 as combustion air. A combustion air blower 120 is provided upstream of the air line 80. The combustion air blower 120 takes in external air and compresses and sends it through the air line 80. The preheating section 90 is provided midway along the air line 80. In the preheating section 90, heat exchange occurs between the air on the air line 80 and the exhaust gas on the exhaust gas line 60. The air heated by the heat exchange is led to the combustion section 20 as combustion air.

[0023] (Collection unit 100) The recovery section 100 is a flow path for recovering unreacted ammonia produced in the decomposition section 50 and returning it to the storage section 30. The recovery section 100 connects the above-mentioned ARU 54 and the storage section 30. A portion of the ammonia that was not thermally decomposed in the decomposition section main body 52 is separated or classified in the ARU 54, and then returned to the storage section 30 through the recovery section 100 for reuse.

[0024] (Action and effect) When the heat treatment equipment 1 is operated, first, ammonia in the storage section 30 is supplied to the decomposition section 50. The gas containing nitrogen and hydrogen produced through thermal decomposition in the decomposition section 50 is combusted with combustion air in the combustion section 20 to produce high-temperature combustion gas. The heat of this combustion gas is used to perform heat treatment such as annealing, quenching, or tempering on the object 200 in the heat treatment furnace 10.

[0025] Conventionally, natural gas, propane gas, coke oven gas (COG), and blast furnace gas (BFG), which contain carbon, have been used as combustion gases for heat treatment. These gases may be mixed and used as combustion gases. However, when these gases are used, the large amount of carbon contained increases the carbon dioxide emissions of the plant. Furthermore, the combustion gas contains thermal NOx, fuel NOx, and the like, which increases the environmental load. Furthermore, in order to deal with NOx levels exceeding environmental regulation values, a separate denitrification device may be required. To solve this problem, the present embodiment employs the above-described configurations.

[0026] According to the above configuration, metals can be heat-treated by burning gas containing hydrogen as a main component, which is produced by decomposing ammonia. Because ammonia is used as a raw material, it is possible to achieve a carbon-free system. Furthermore, because ammonia is decomposed before combustion, the amount of nitrogen oxides produced can be significantly reduced compared to when ammonia is directly combusted. Therefore, the environmental impact of the heat treatment equipment 1 can be significantly reduced compared to conventional systems. Furthermore, because the amount of nitrogen oxides produced can be significantly reduced, it is possible to omit the installation of a denitration device in cases where a denitration device would have been required with conventional combustion gases, and simplify the equipment.

[0027] Furthermore, the combustion speed and combustion stability can be significantly improved compared to direct combustion of ammonia. In addition, compared to direct circulation of ammonia, the possibility of corrosion and other deterioration of piping and valves can be minimized. Therefore, it is possible to continue stable operation of the heat treatment equipment 1 for a long period of time.

[0028] According to the above configuration, when decomposing ammonia, the exhaust gas from the heat treatment furnace 10 is used as thermal energy for the catalytic reaction. This eliminates the need to introduce a heat medium from an external source. This reduces the energy consumption of the heat treatment equipment 1 and significantly improves energy efficiency. This makes it possible to significantly reduce the operating costs of the heat treatment equipment 1 compared to conventional methods. As a result, the retail price of products produced using the heat treatment equipment 1 can be kept low.

[0029] According to the above configuration, combustion air is supplied to the heat treatment furnace 10 through the air line 80. This improves the combustion efficiency of the gas in the combustion section 20. Furthermore, this combustion air is heated in the preheating section 90 using the thermal energy of the exhaust gas. This makes it possible to maintain the combustion temperature of the gas in the combustion section 20 at an optimum state. This allows the heat treatment to be completed in a shorter time with even higher efficiency. As a result, it becomes possible to significantly improve the production efficiency of the final product.

[0030] According to the above configuration, unreacted ammonia generated in the decomposition section 50, i.e., ammonia that has not been decomposed, is recovered by the recovery section 100 and returned to the storage section 30. This allows the ammonia used as a fuel raw material to be fully utilized without any waste. Furthermore, since the amount of ammonia used in the entire facility can be reduced, it is possible to significantly reduce operating costs. As a result, the price of the final product can be kept low.

[0031] The first embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above-described configurations without departing from the spirit and scope of the present disclosure.

[0032] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 2. Note that the same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0033] 2, in this embodiment, the configurations of the decomposition section 50 and the exhaust gas line 60 are different from those of the first embodiment. Specifically, the decomposition section 50 has only the above-mentioned decomposition section main body 52 and ARU 54, and does not have the first heat exchanger 51 or the second heat exchanger 53. In addition, the exhaust gas line 60 does not pass through the decomposition section main body 52.

[0034] Furthermore, the heat treatment equipment 1 according to this embodiment further includes a water storage section 130, a steam generation section 140, and a steam line 150. The steam generation section 140 generates steam by heating water supplied from the water storage section 130. The steam generation section 140 is a heat exchanger. Exhaust gas flowing on the exhaust gas line 60 is used as a heat medium for the steam generation section 140. In other words, the steam generation section 140 is provided at a position midway along the exhaust gas line 60. Steam is generated when water boils due to the heat of the exhaust gas.

[0035] The steam generated in the steam generating section 140 is supplied to the decomposition section main body 52 through the steam line 150. That is, the steam line 150 connects the steam generating section 140 and the decomposition section main body 52. ​​In the decomposition section main body 52, the steam is used as a heat source for the catalytic reaction. As a result, steam is supplied at a temperature of 300°C or higher at the inlet of the decomposition section main body 52, for example.

[0036] (Action and effect) According to the above configuration, steam is used as a heat source for ammonia decomposition. To generate this steam, thermal energy from the exhaust gas is used. This reduces the energy consumption of the heat treatment equipment 1 and significantly improves energy efficiency. This makes it possible to significantly reduce the operating costs of the heat treatment equipment 1 compared to conventional methods. As a result, the retail price of products produced using the heat treatment equipment 1 can be kept low. In addition, since there is no need to directly supply the exhaust gas to the decomposition section 50, the risk of dust originating from the exhaust gas accumulating on the catalyst, piping, etc. included in the decomposition section 50 can be avoided. This makes it possible to minimize the time and cost required for maintenance of the heat treatment equipment 1.

[0037] Furthermore, with the above configuration, the exhaust gas does not pass through the decomposition unit main body 52, so the NOx contained in the exhaust gas does not come into contact with the pipes and valves of each section. This eliminates the possibility of corrosion of these pipes and valves. In particular, when the equipment is started or stopped, the temperature of the decomposition unit main body 52 is expected to reach approximately 100°C. At this temperature range, there is a risk that the condensed water produced by the combustion of ammonia will react with NOx to produce highly corrosive nitric acid. However, with the above configuration, the exhaust gas does not come into contact with ammonia, so it is possible to eliminate the possibility of corrosive substances such as nitric acid being produced. This allows the heat treatment equipment 1 to continue operating stably for an even longer period of time.

[0038] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present disclosure.

[0039] For example, in each of the above-described embodiments, the combustion section 20 has been described as having only a nozzle 21 and an ignition device. However, as a modified example, the configuration shown in FIG. 3 can also be adopted. Specifically, the combustion section 220 has a nozzle 21, an ignition device (not shown), and a casing 221. The casing 221 covers the nozzle 21 and the ignition device from the outside. When a flame is emitted from the nozzle 21, the heat is dissipated into the heat treatment furnace 10 through the casing 221. In this case, it is desirable that the upstream portion of the exhaust gas line 60 be branched so as to collect exhaust gas from the space within each casing 221.

[0040] According to the above configuration, the combustion section 220 uses a so-called radiant tube system, which includes a nozzle 21 and a casing 221. In this system, the metal is heat-treated not by heat from a combustion flame, but by radiant heat from the combustion gas generated within the casing 221. This minimizes the risk of excessive heat input to the metal or unexpected changes in the metal. This further improves the quality of the final product and significantly increases the yield in the production process.

[0041] In addition, it is also possible to further add the first heat exchanger 51 and the second heat exchanger 53 described in the first embodiment to the configuration described in the second embodiment. Also, it is possible to adopt a configuration without the preheating section 90. Furthermore, it is also possible to store gaseous ammonia in the storage section 30 instead of liquid ammonia and use it as the raw material gas. In addition, the air line 80 for guiding combustion air may not be necessary depending on the combustion characteristics and combustion efficiency of the combustion section 20. Even with these configurations, it is possible to obtain the main effect of significantly reducing the environmental load, similar to the above-mentioned configurations.

[0042] Furthermore, in the above embodiment, an example has been described in which the ARU 54 is provided. However, depending on the specifications and requirements of the final product, it may be acceptable for a small amount of ammonia to remain. In this case, the ARU 54 may be omitted.

[0043] Heat treatment equipment in the industrial field is not only used for annealing in the steel metals field as exemplified in this embodiment, but also for firing in the ceramics and civil engineering industry and for decomposition reactions in the chemical and petroleum industries, and similar effects can be obtained by adopting the contents of the present disclosure.

[0044] The heat treatment equipment 1 described in each embodiment can be understood, for example, as follows.

[0045] (1) The heat treatment equipment 1 according to the first aspect is a heat treatment equipment 1 for subjecting an object 200 to heat treatment, and includes a heat treatment furnace 10 into which the object 200 is introduced, a storage section 30 for storing ammonia, a supply line 40 for extracting the ammonia from the storage section 30, a decomposition section 50 provided on the supply line 40 for decomposing the ammonia into hydrogen and nitrogen, and a combustion section 20 provided within the heat treatment furnace 10 for generating combustion gas by combusting at least the hydrogen from the gas supplied from the decomposition section 50 through the supply line 40.

[0046] According to the above configuration, ammonia is used as the raw material, so that carbon-free operation can be achieved.

[0047] (2) The heat treatment equipment 1 according to the second aspect is the heat treatment equipment 1 of (1), further comprising an exhaust gas line 60 that guides high-temperature exhaust gas discharged from the heat treatment furnace 10 to the decomposition section 50, and the decomposition section 50 decomposes the ammonia through a catalytic reaction using the heat of the exhaust gas.

[0048] According to the above configuration, the amount of energy consumed by the heat treatment equipment 1 can be reduced, and the energy efficiency can be significantly improved.

[0049] (3) The heat treatment equipment 1 according to the third aspect is the heat treatment equipment 1 of (2), further comprising a steam generating section 140 provided on the exhaust gas line 60 to generate steam by heat exchange between water introduced from the outside and the exhaust gas, and a steam line 150 to supply the steam to the decomposition section 50 as a heat source.

[0050] According to the above configuration, the amount of energy consumed by the heat treatment equipment 1 can be reduced, and the energy efficiency can be significantly improved.

[0051] (4) The heat treatment equipment 1 according to the fourth aspect is the heat treatment equipment 1 of (2) or (3), further comprising an air line 80 for supplying combustion air introduced from the outside into the heat treatment furnace 10, and a preheating section 90 provided on the air line 80 for heat exchange between the exhaust gas and the combustion air.

[0052] According to the above configuration, the combustion efficiency of gas in the combustion section 20 can be improved.

[0053] (5) The heat treatment equipment 1 according to the fifth aspect is the heat treatment equipment 1 according to any one of the aspects (1) to (4), and further includes a recovery section 100 that recovers unreacted ammonia produced in the decomposition section 50 and returns it to the storage section 30.

[0054] According to the above configuration, ammonia, which is a raw material for fuel, can be utilized to the maximum extent without being wasted.

[0055] (6) The heat treatment equipment 1 according to the sixth aspect is the heat treatment equipment 1 according to any one of the aspects (1) to (5), wherein the combustion section 20 has a nozzle 21 for injecting the gas supplied from the decomposition section 50 and a casing 221 for covering the nozzle 21 from the outside.

[0056] According to the above configuration, the quality of the final product is further improved, and the yield in the production process can be significantly improved.

[0057] (7) The heat treatment equipment 1 according to a seventh aspect is the heat treatment equipment 1 according to any one of the aspects (1) to (6), wherein the decomposition section has a decomposition section main body that decomposes ammonia and a heat exchanger that adjusts the temperature of the ammonia flowing through the decomposition section main body, and the heat exchanger adjusts the temperature of the ammonia using the heat of the exhaust gas.

[0058] According to the above configuration, the energy efficiency of the entire facility can be further improved.

[0059] (8) The heat treatment equipment 1 according to an eighth aspect is the heat treatment equipment 1 according to any one of the aspects (1) to (7), wherein the temperature of the combustion gas is 800°C or higher and 1200°C or lower.

[0060] According to the above configuration, the amount of thermal NOx produced can be reduced. [Explanation of symbols]

[0061] 1...Heat treatment equipment 10...Heat treatment furnace 20...Combustion section 21...Nozzle 30...Storage section 40...Supply line 50...Decomposition section 51...First heat exchanger 52...Decomposition section main body 53...Second heat exchanger 54...ARU 60...Exhaust gas line 70...Chimney 80...Air line 90...Preheating section 100...Recovery section 110...Exhaust gas blower 120...Combustion air blower 130...Water storage section 140...Steam generation section 150...Steam line 200...Object 220...Combustion section 221...Casing

Claims

1. A heat treatment facility for performing heat treatment on an object, a heat treatment furnace into which the object is introduced; a storage unit that stores ammonia; a supply line for extracting the ammonia from the reservoir; a decomposition section provided on the supply line for decomposing the ammonia into hydrogen and nitrogen; a combustion unit provided in the heat treatment furnace, the combustion unit generating a combustion gas by combusting at least the hydrogen in the gas supplied from the decomposition unit through the supply line; Heat treatment equipment equipped with:

2. an exhaust gas line that guides high-temperature exhaust gas discharged from the heat treatment furnace to the decomposition section; The heat treatment facility according to claim 1 , wherein the decomposition section decomposes the ammonia through a catalytic reaction using heat from the exhaust gas.

3. a steam generating unit provided on the exhaust gas line and configured to generate steam by exchanging heat between water introduced from the outside and the exhaust gas; a steam line that supplies the steam to the decomposition section as a heat source; The heat treatment facility of claim 2 further comprising:

4. an air line for supplying combustion air introduced from the outside into the heat treatment furnace; a preheating section provided on the air line for heat exchange between the exhaust gas and the combustion air; The heat treatment facility according to claim 2 or 3, further comprising:

5. The heat treatment facility according to claim 1 , further comprising a recovery section that recovers unreacted ammonia produced in the decomposition section and returns the recovered ammonia to the reservoir section.

6. the combustion unit includes a nozzle for injecting the gas supplied from the decomposition unit; a casing that covers the nozzle from the outside; The heat treatment facility according to any one of claims 1 to 3, comprising:

7. The decomposition unit a decomposition unit main body that decomposes ammonia; a heat exchanger for adjusting the temperature of the ammonia flowing through the decomposition unit body; and The heat treatment facility according to claim 2 or 3, wherein the heat exchanger adjusts the temperature of the ammonia by using the heat of the exhaust gas.

8. The heat treatment facility according to claim 1 , wherein the temperature of the combustion gas is 800° C. or higher and 1200° C. or lower.

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