Atmosphere furnace and atmosphere control method

Abstract

The present invention provides an atmosphere furnace and an atmosphere control method that can reduce carbon dioxide emissions. [Solution] An atmospheric furnace 10 for heat-treating a workpiece inside a furnace chamber filled with an atmospheric gas containing CO and CO2, comprising: a furnace body 11 having a furnace chamber; a gas supply system 12 connected to the furnace body 11 and supplying atmospheric gas to the furnace chamber; a dew point regulator 13 connected to the furnace body 11 and adjusting the dew point temperature of the atmospheric gas; an analyzer 14 for analyzing the CO concentration and CO2 concentration in the furnace chamber; a dew point meter 15 for measuring the dew point temperature of the atmospheric gas in the furnace chamber; and a controller 16 connected to the dew point regulator 13, analyzer 14 and dew point meter 15, which controls the dew point temperature of the atmospheric gas to decrease and reduce the CO2 concentration in the furnace chamber.

Description

Technical Field

[0001] The present invention relates to an atmosphere furnace for heat-treating an object to be treated and an atmosphere control method for controlling the atmosphere in the furnace chamber of the atmosphere furnace.

Background Art

[0002] Heat treatment such as annealing using steel materials or the like as an object to be treated is usually performed by using an atmosphere furnace filled with an atmosphere gas in the furnace and making the atmosphere in the furnace where the object to be treated is accommodated suitable for heat treatment. Regarding heat treatment using an atmosphere furnace, Patent Documents 1, 2, and 3 disclose an atmosphere control method in which an endothermic reformed gas is used as the atmosphere gas, and the carbon potential (hereinafter also referred to as "CP") indicating the carbon concentration (carbon equivalent) of the atmosphere in the furnace is controlled by adjusting the supply amount of the endothermic reformed gas into the furnace. The endothermic reformed gas is a gas reaction-generated from a hydrocarbon gas such as propane and is a mixed gas containing CO, CO2, H2, etc. Further, CP can be calculated based on the CO concentration and CO2 concentration in the atmosphere or gas. In addition, Patent Document 4 discloses a method of separating carbon dioxide (CO2) from flue gas using a membrane for the purpose of reducing carbon dioxide (CO2) emissions from the exhaust gas of the furnace, characterized in that the flue gas has a temperature exceeding the dew point curve of water vapor before entering the membrane. In addition, Patent Document 5 discloses a method for reducing the dew point of the atmosphere gas in the furnace using a dryer that dehumidifies the gas to a dew point of -45°C or lower for the purpose of improving the adhesion of plating.

Prior Art Documents

Patent Documents

[0003] <000D023>

Patent Document 1

Patent Document 2

Patent Document 3

[0004] In heat treatment, exhaust gas containing CO2 is discharged from the atmosphere furnace to the outside of the furnace. From the perspective of carbon-free and carbon-neutrality, it is desirable to reduce CO2 emissions, which are greenhouse gases. The atmosphere control methods disclosed in Patent Documents 1 to 3 control the CP by increasing or decreasing the supply amount of endothermic reformed gas, which is a mixed gas of CO and CO2. However, because the CO2 concentration in the endothermic reformed gas used is kept at a constant (fixed) value, the utilization efficiency of the endothermic reformed gas is poor, such as only CO being used and CO2 being exhausted without being used, resulting in a large amount of CO2 being wasted and discharged. The method disclosed in Patent Document 4 separates CO2 from exhaust gas discharged outside the furnace using a membrane, but it is essentially a technique for capturing CO2 that is about to be discharged outside the furnace, and does not consider the treatment or handling of the separated CO2. The method disclosed in Patent Document 5 is a method for reducing the dew point of an atmospheric gas aimed at improving the adhesion of plating, and does not take into consideration the reduction of CO2 emissions.

[0005] The present invention aims to solve the problems of the conventional technology and to provide an atmosphere furnace and atmosphere control method that can reduce carbon dioxide emissions. [Means for solving the problem]

[0006] To solve the above problems, the present invention is shown below. [1] The atmospheric furnace of the present invention is an atmospheric furnace that heat-treats an object to be treated inside a furnace chamber filled with an atmospheric gas containing CO and CO2, A furnace body comprising the aforementioned furnace chamber, A gas supply system connected to the furnace body and supplying the atmospheric gas to the furnace chamber, A dew point regulator connected to the furnace body for adjusting the dew point temperature of the atmospheric gas, An analyzer for analyzing the CO concentration and CO2 concentration in the aforementioned furnace chamber, A dew point meter for measuring the dew point temperature of the atmospheric gas in the furnace chamber, The gist of the system is that it includes a controller connected to the dew point adjuster, the analyzer, and the dew point meter, which controls the system to lower the dew point temperature of the atmospheric gas and thereby reduce the CO2 concentration in the furnace chamber. [2] In the atmospheric furnace of the present invention, The aforementioned dew point adjuster is A gas circulation system that circulates the atmospheric gas between the furnace body and the system, A cooler for cooling the atmospheric gas supplied from the furnace chamber of the furnace body via the gas circulation system, The system may also include a regenerator that adsorbs and removes moisture contained in the atmospheric gas cooled by the cooler, thereby regenerating the atmospheric gas. [3] In the atmospheric furnace of the present invention, The regenerator is switchable between an adsorption state in which it adsorbs moisture contained in the atmospheric gas and a standby state in which it desorbs the adsorbed moisture. The dew point regulator comprises a plurality of the regenerators, Some of the multiple regenerators may be in an adsorption state, while the other regenerators may be in a standby state. [4] In the atmospheric furnace of the present invention, The aforementioned atmospheric gas may be an endothermic modified gas. [5] In the atmospheric furnace of the present invention, The heat treatment may include heating, soaking, and slow cooling. [6] In the atmospheric furnace of the present invention, The controller can be adjusted to lower the dew point temperature of the ambient gas to 0°C or below. [7] In the atmosphere furnace of the present invention, the controller includes an arithmetic means for calculating the carbon potential of the furnace chamber based on the CO concentration and the CO2 concentration obtained from the analyzer, and a first CP control means for controlling the carbon potential by operating the dew point adjuster to adjust the CO2 concentration in the furnace chamber so that the carbon potential becomes a preset value according to the heat treatment. [8] In the atmosphere furnace of the present invention, the gas supply system includes a gas generator for generating the atmosphere gas from air and hydrocarbon gas, the gas generator is connected to the controller, the controller includes an arithmetic means for calculating the carbon potential of the furnace chamber based on the CO concentration and the CO2 concentration obtained from the analyzer, and a second CP control means for controlling the carbon potential by operating the gas generator to adjust the CO2 concentration in the atmosphere gas so that the carbon potential becomes a preset value according to the heat treatment. [9] In the atmosphere furnace of the present invention, the furnace body may further be provided with a purge device connected thereto for supplying an inert gas to the furnace chamber to purge the inside of the furnace chamber.

[10] The atmosphere control method of the atmosphere furnace of the present invention is an atmosphere control method for controlling the atmosphere in the furnace chamber of the atmosphere furnace described in [1], and includes a first management step of managing the operation of the dew point adjuster so that the carbon potential of the furnace chamber calculated based on the CO concentration and the CO2 concentration obtained from the analyzer becomes a preset value according to the heat treatment in order to make the atmosphere in the furnace chamber suitable for the heat treatment. The first management step includes a step of taking in the atmosphere gas from the furnace chamber, a step of lowering the dew point temperature of the atmosphere gas, A step of returning the atmosphere gas with the dew point temperature lowered to the furnace chamber at a temperature of 650°C or higher to reduce the CO2 concentration in the furnace chamber is the gist.

[11] The atmosphere control method of the atmosphere furnace of the present invention is an atmosphere control method for controlling the atmosphere in the furnace chamber of the atmosphere furnace described in [1], In order to make the atmosphere in the furnace chamber suitable for the heat treatment, the first management step of managing the operation of the dew point regulator and the second management step of managing the operation of the gas supply system are provided so that the carbon potential of the furnace chamber calculated based on the CO concentration and the CO2 concentration obtained from the analyzer becomes a preset value according to the heat treatment. The first management step includes a step of taking in the atmosphere gas from the furnace chamber, a step of lowering the dew point temperature of the atmosphere gas, and a step of returning the atmosphere gas with the dew point temperature lowered to the furnace chamber at a temperature of 650°C or higher to reduce the CO2 concentration in the furnace chamber. The second management step is mainly characterized by including a step of reducing or increasing the CO2 concentration in the atmosphere gas supplied to the furnace chamber.

[12] In the atmosphere control method of the atmosphere furnace of the present invention, The first management step can lower the dew point temperature of the atmosphere gas to 0°C or lower.

[13] In the atmosphere control method of the atmosphere furnace of the present invention, A furnace pressure gauge for measuring the furnace pressure of the atmosphere in the furnace chamber is provided in the furnace body. After setting the carbon potential of the furnace chamber to the set value, a furnace pressure control step of controlling the furnace pressure of the furnace chamber is provided. The furnace pressure control step is Comparing the furnace pressure obtained from the furnace pressure gauge with a preset set pressure according to the heat treatment, and supplying the atmosphere gas to the furnace chamber or exhausting the atmosphere gas from the furnace chamber so that the furnace pressure becomes the set pressure can be provided.

Advantages of the Invention

[0007] The present invention relates to an atmospheric furnace and an atmospheric furnace atmosphere control method, which reduces the amount of water vapor in the atmospheric gas using a dew point regulator. This reduces the amount of carbon dioxide in the atmospheric gas through a water-gas shift reaction, a chemical reaction, thereby reducing carbon dioxide (CO2) emissions. [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram showing one embodiment of the atmospheric furnace of the present invention. [Figure 2] A flowchart illustrating an example of the first control step in the atmosphere control method of the present invention. [Figure 3] A flowchart illustrating an example of the second control step in the atmosphere control method of the present invention. [Modes for carrying out the invention]

[0009] The matters presented herein are illustrative and illustrative to illustrate embodiments of the present invention, and are intended to provide what is considered to be the most effective and readily understandable explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond what is necessary for a fundamental understanding of the invention, and the description, in conjunction with the drawings, will make it clear to those skilled in the art how some forms of the present invention are actually embodied.

[0010] [1] Atmosphere furnace The present invention is an atmospheric furnace that heat-treats an object to be treated inside a furnace chamber filled with an atmospheric gas containing CO and CO2, A furnace body comprising the aforementioned furnace chamber, A gas supply system connected to the furnace body and supplying the atmospheric gas to the furnace chamber, A dew point regulator connected to the furnace body for adjusting the dew point temperature of the atmospheric gas, An analyzer for analyzing the CO concentration and CO2 concentration in the aforementioned furnace chamber, A dew point meter for measuring the dew point temperature of the atmospheric gas in the furnace chamber, The system is characterized by comprising a controller connected to the dew point adjuster, the analyzer, and the dew point meter, which controls the system to lower the dew point temperature of the atmospheric gas and thereby reduce the CO2 concentration in the furnace chamber.

[0011] Figure 1 is a block diagram showing one embodiment of the atmospheric furnace of the present invention. The atmosphere furnace 10 of the present invention is for performing heat treatment on a workpiece. The heat treatment performed by this atmosphere furnace 10 may include heating, soaking, and slow cooling. That is, the atmosphere furnace 10 may perform three heat treatments on a workpiece: heating, soaking, and slow cooling.

[0012] The heat treatment is not particularly limited in terms of its purpose or method. The purposes of processing include strain removal, stress relief, homogenization of the structure, and change of properties. Processing methods include annealing, quenching, tempering, and normalizing. As a heat treatment that includes heating, soaking, and slow cooling, preferably, annealing is performed on an object made of iron-based material, with the purpose of removing strain, softening the structure, and improving ductility. Furthermore, in addition to heating, soaking, and slow cooling, heat treatment may also include processes such as purging, which involves exhausting gases from inside the furnace chamber to the outside; preheating, which involves preheating the object; and cooling, which involves allowing the object to cool.

[0013] As for the processing methods of an atmospheric furnace, there are two types: a batch type in which heat treatment is applied intermittently to the workpieces to be processed while they are kept inside the furnace, and a continuous type in which heat treatment is applied continuously to the workpieces to be processed as they are transported inside the furnace. In the batch type, the atmosphere furnace 10 can change temperature conditions and other parameters for each heat treatment cycle, which has the advantage of being able to handle a variety of materials, such as being able to heat treat two or more materials with different iron-based compositions using the same atmosphere furnace 10. Furthermore, the batch type atmosphere furnace 10 also has advantages such as a simplified configuration and space saving. In the case of a continuous atmosphere furnace 10, the interior of the furnace body 11 is divided into multiple chambers such as a heating chamber, a soaking chamber, and a slow cooling chamber, according to each process included in the heat treatment, such as heating, soaking, and slow cooling. Since the temperature conditions of each chamber can be adjusted and maintained according to the temperature conditions of each process, it has the advantage of being able to handle mass production of the workpieces to be processed. Furthermore, the continuous atmosphere furnace 10 also has the advantage of being able to shorten the processing time and increase the number of items processed per unit time. The atmosphere furnace 10 of the present invention is not particularly limited in terms of processing method, and can employ either a continuous or batch type.

[0014] In this invention, the atmospheric furnace can reduce carbon dioxide in the atmospheric gas through a water-gas shift reaction by reducing the moisture content in the atmospheric gas using a dew point regulator. In other words, the atmospheric furnace of the present invention can arbitrarily reduce the amount of carbon dioxide in the atmospheric gas by reducing the moisture content in the atmospheric gas, that is, by lowering the dew point. In an atmospheric furnace used to heat-treat objects, arbitrarily reducing the amount of carbon dioxide in the atmospheric gas enables control of the furnace chamber's carbon potential by adjusting the CO2 concentration (hereinafter also referred to as "CP control"). In other words, the atmospheric furnace of the present invention can reduce carbon dioxide (CO2) emissions by adjusting the dew point. Furthermore, the atmospheric furnace of the present invention can control the CP of the furnace chamber based on adjusting the concentration of carbon dioxide (CO2) in the atmospheric gas by adjusting the dew point.

[0015] In a batch-type atmosphere furnace, heating, soaking, and slow cooling are performed in a single furnace chamber of the furnace body 11. A batch-type atmosphere furnace allows for dew point adjustment at each stage of the heating, soaking, and slow cooling processes, based on the objective of controlling the CP (cooling point) of a single furnace chamber. In a continuous atmosphere furnace, the interior of the furnace body 11 is divided into multiple furnace chambers corresponding to various processes such as heating, soaking, and slow cooling. A continuous atmosphere furnace allows for dew point adjustment in each furnace chamber, based on the perspective of controlling the CP (cooling point) of the multiple furnace chambers. In other words, each of the processes included in heat treatment, such as heating, soaking, and slow cooling, has a different optimal temperature (processing temperature), and the optimal carbon potential (CP) for each process also differs. Therefore, in a batch-type atmosphere furnace, the atmosphere, such as the temperature and CP of a single furnace chamber, is changed and adjusted according to each process, such as heating, soaking, and slow cooling. In relation to adjusting the atmosphere during each of these processes, such as heating, soaking, and slow cooling, dew point adjustment can be performed as CP control. Furthermore, in a continuous atmosphere furnace, the temperature and atmosphere (CP, etc.) of each of the multiple furnace chambers, such as the heating chamber where heat treatment is performed, the soaking chamber where soaking treatment is performed, and the slow cooling chamber where slow cooling treatment is performed, are adjusted in each chamber to suit the respective treatment. In relation to adjusting the atmosphere in each of these furnace chambers, dew point adjustment can be performed as CP control.

[0016] The objects to be processed in the atmosphere furnace 10 are not particularly limited in terms of shape, purpose, materials used, etc., as long as they are subjected to heat treatment. Examples of shapes of the object to be processed include linear, tubular, columnar, plate-shaped, rectangular, and the like. Examples of applications for the processed materials include parts for automobiles and equipment, as well as building materials. Examples of materials used for processing include iron and iron-based materials such as iron alloys like steel. Iron-based materials are not particularly limited as long as they consist of iron (Fe) containing carbon (C). Iron-based materials may include alloys containing silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), nickel (Ni), chromium (Cr), tungsten (W), vanadium (V), molybdenum (Mo), cobalt (Co), etc., in addition to carbon and iron. Specific examples of iron-based materials include ordinary steel, special steel, cast and forged steel, and cast iron.

[0017] The following describes the various components of the atmosphere furnace 10. (1) Furnace body The furnace body 11 is used to actually perform heat treatment on the workpiece in the atmosphere furnace 10 (see Figure 1), and it has a furnace chamber (not shown) inside for housing the workpiece. When the processing method of the atmosphere furnace 10 is batch type, the number of furnace chambers provided in the furnace body 11 can usually be one. In this case, the workpiece is kept in one furnace chamber of the furnace body 11 and subjected to at least three heat treatments: heating, soaking, and slow cooling. When the processing method of the atmosphere furnace 10 is continuous, the number of furnace chambers provided in the furnace body 11 can usually be multiple, and can be the same number as the number of processes included in the heat treatment. For example, if the heat treatment includes three processes: heating, soaking, and slow cooling, the furnace chambers provided in the furnace body 11 can be a heating chamber, a soaking chamber, and a slow cooling chamber.

[0018] In a continuous type, the workpiece is transported through the furnace body 11 across multiple furnace chambers, and each chamber undergoes the respective processes included in the heat treatment. For example, if the furnace body 11 has three furnace chambers—a heating chamber, a soaking chamber, and a slow cooling chamber—the workpiece is transported in the order of heating chamber, soaking chamber, and slow cooling chamber, and undergoes heat treatment in the heating chamber, soaking treatment in the soaking chamber, and slow cooling treatment in the slow cooling chamber. In the case of a continuous type, the furnace body 11 may have doors, partitions, curtains, etc., that separate the multiple furnace chambers. In the case of a continuous type, the furnace body 11 may be equipped with measuring instruments such as flow meters, observation instruments, and analyzers to grasp the inflow (IN) and outflow (OUT) of atmospheric gas in each furnace chamber, from the viewpoint of controlling CP.

[0019] The furnace body 11 is not particularly limited in terms of materials used, shape, size, internal volume, heating / cooling method, etc., as long as it is appropriate for the processing method of the atmosphere furnace 10. For example, the furnace body 11 may include, in addition to the furnace chamber in which heat treatment including heating, soaking, and slow cooling is performed, chambers for treatments other than heat treatment, such as a pre-chamber and a post-chamber. The anteroom can be used to hold the object W before heat treatment, or to preheat the object W before heat treatment. The post-treatment chamber can be used to retain the object W after heat treatment, or to allow the object W to cool to room temperature after heat treatment.

[0020] The furnace body 11 may have a temperature controller for adjusting the temperature of the atmosphere in the furnace chamber (hereinafter also referred to as "furnace temperature"). The temperature controller is not particularly limited in terms of configuration, type, etc., as long as it is capable of adjusting the furnace temperature. As a temperature controller, it is preferable to use one that does not release carbon dioxide contained in combustion gases or air into the furnace body. Examples include burners, heaters, and heat exchangers installed in the furnace chamber of the furnace body 11.

[0021] A burner uses gas, oil, or other fuels to raise the temperature inside the furnace body 11 using the heat generated by the combustion of those fuels. A heater is a device that converts electricity into thermal energy and uses that thermal energy to raise the temperature inside the furnace body 11. Examples include resistance heaters, infrared heaters, and induction heaters. A heat exchanger is a device that uses tubular heat exchange tubes through which a heat transfer medium such as combustion gas or a coolant such as air is passed, thereby raising or lowering the temperature inside the furnace body 11 through heat exchange. Specific examples of heat exchangers include radiant tube burners and cooling tubes.

[0022] The temperature controller is electrically connected to the controller 16, allowing the controller 16 to control operations related to heating and cooling. The temperature controller, thus controlled by the controller 16, can adjust the furnace temperature so that the furnace chamber of the furnace body 11 reaches the optimal temperature for heating, soaking, and slow cooling during heat treatment. In this case, the amount of fuel used for adjusting the furnace temperature can be optimized, avoiding wasteful use of fuel. In particular, by limiting fuel usage to an appropriate amount, carbon dioxide emissions can also be reduced. Furthermore, the optimal temperatures for each process—heating, soaking, and slow cooling—can be predetermined according to the material used for the workpiece (e.g., iron-based material), the purpose of the heat treatment (e.g., annealing), etc. Therefore, the optimal temperatures for each process—heating, soaking, and slow cooling—can be stored in the controller 16 as preset temperatures, and the temperature regulator, whose operation is controlled by the controller 16, can adjust the furnace temperature to reach the preset temperature (optimal temperature) corresponding to each process, thereby controlling the ambient temperature.

[0023] For example, in a heating process, the temperature controller adjusts the furnace temperature so that the temperature of the workpiece rises at a constant rate during the process. The upper limit of the furnace temperature in the heating process is preferably set to a temperature suitable for soaking. In the soaking process, the temperature controller adjusts the furnace temperature so that the temperature of the workpiece being processed is maintained within the optimal range for soaking. In the slow cooling process, the temperature controller adjusts the furnace temperature so that the temperature of the material being processed decreases at a constant rate during processing. The lower limit of the furnace temperature in the slow cooling process can be arbitrarily determined depending on the material of the material being processed.

[0024] (2) Gas supply system The gas supply system 12 is connected to the furnace body 11 and supplies atmospheric gas to the furnace chamber. A gas generator 21 and a first control valve 22 can be connected to this gas supply system 12 (see Figure 1). The gas generator 21 generates an atmospheric gas from air and hydrocarbon gas, and is connected to the furnace body 11 via the gas supply system 12. The first adjustment valve 22 is used to adjust the amount of atmospheric gas supplied from the gas generator 21 to the furnace body 11 by adjusting its opening.

[0025] The gas generator 21 includes a transformer 211, an air supply system 212 that supplies air to the transformer 211, and a raw material supply system 213 that supplies hydrocarbon gas as a raw material to the transformer 211 (see Figure 1). An air adjustment valve 214 can be connected to the air supply system 212. When the air adjustment valve 214 is connected, the amount of air supplied to the transformer 211 can be adjusted by adjusting the opening degree of the air adjustment valve 214. A raw material adjustment valve 215 can be connected to the raw material supply system 213. When the raw material adjustment valve 215 is connected, the amount of hydrocarbon gas supplied to the transformer 211 can be adjusted by adjusting the opening degree of the raw material adjustment valve 215.

[0026] The first adjustment valve 22, the air adjustment valve 214, and the raw material adjustment valve 215 are not particularly limited in type, as long as they can be operated by the controller 16 and each can open and close the system to which it is connected. For example, solenoid valves, electric valves, etc., can be used. Among these, electric valves are preferred for use in the first adjustment valve 22, the air adjustment valve 214, and the raw material adjustment valve 215 because the amount of opening and closing can be adjusted by operating the controller 16. The hydrocarbon gas used as a raw material is not particularly limited and can include methane, butane, propane, etc., and propane can usually be used.

[0027] The transformer 211 can mix a hydrocarbon gas with air and react the hydrocarbon gas (e.g., propane gas; C3H8) with oxygen (O2) in the air as shown in formula (1) below to generate carbon monoxide (CO) and hydrogen (H2). C3H8+(3 / 2)O2→ 3CO+4H2...Equation (1) In addition to oxygen (O2), air also contains carbon dioxide (CO2), nitrogen (N2), and water (H2O). Therefore, the gas generator 21 having the transformer 211 can generate an endothermic transformed gas (hereinafter also referred to as "RX gas") from air and hydrocarbon gas, which is a mixed gas containing multiple types of gases such as carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), water (H2O), and nitrogen (N2). The RX gas generated by this gas generator 21 is supplied to the furnace body 11 as an atmospheric gas via the gas supply system 12.

[0028] The transformer 211 is not particularly limited in its configuration, but it may be equipped with a catalyst for reacting air and hydrocarbon gas. A nickel catalyst can usually be used as the catalyst, and the reaction can be made by heating the catalyst to a high temperature (around 1000-1100°C) and bringing it into contact with air and hydrocarbon gas. The gas generator 21 is not particularly limited in its configuration, and for example, it can be configured such that a blower, compressor, fan, or other device for supplying air is connected to the air supply system 212, or a tank or cylinder for storing hydrocarbon gas is connected to the raw material supply system 213.

[0029] The gas generator 21 can adjust the CO2 concentration in the RX gas. One method for adjusting the CO2 concentration is to adjust the amount of air and hydrocarbon gas supplied to the transformer 211. Another method for adjusting the CO2 concentration is to adjust only the amount of air supplied to the transformer 211.

[0030] Specifically, when increasing the CO2 concentration by adjusting the supply of air and hydrocarbon gas, the supply of air to the transformer 211 is increased and / or the supply of hydrocarbon gas is decreased. Increasing the supply of air increases the amount of carbon dioxide (CO2) in the RX gas, resulting in a higher CO2 concentration. Conversely, decreasing the supply of hydrocarbon gas reduces the amounts of carbon monoxide (CO) and hydrogen (H2) in the RX gas, leading to a higher CO2 concentration.

[0031] When the CO2 concentration is to be lowered by adjusting the supply of air and hydrocarbon gas, the supply of air to the transformer 211 is reduced and / or the supply of hydrocarbon gas is increased. Reducing the supply of air decreases the amount of carbon dioxide (CO2) in the RX gas, resulting in a lower CO2 concentration. Conversely, increasing the supply of hydrocarbon gas increases the amounts of carbon monoxide (CO) and hydrogen (H2) in the RX gas, leading to a lower CO2 concentration.

[0032] In practice, adjusting the CO2 concentration in the RX gas can be easily done simply by adjusting the amount of air supplied to the transformer 211. Alternatively, when adjusting the CO2 concentration in RX gas, if adjustment of the CO concentration or fine and precise adjustment of the CO2 concentration is required, it is desirable to adjust both the supply rate of air and the supply rate of hydrocarbon gas.

[0033] Specifically, when increasing the CO2 concentration by adjusting only the amount of air supplied, the amount of air supplied to the transformer 211 is increased, and accordingly the amount of carbon dioxide (CO2) in the RX gas increases, resulting in a higher CO2 concentration. Alternatively, if the CO2 concentration is lowered solely by adjusting the amount of air supplied, the amount of air supplied to the transformer 211 is reduced, and accordingly, the amount of carbon dioxide (CO2) in the RX gas decreases, resulting in a lower CO2 concentration.

[0034] Furthermore, when adjusting the CO2 concentration in the RX gas solely by adjusting the amount of air supplied, it is desirable to always supply a constant amount (fixed amount) of hydrocarbon gas to the transformer 211. In this case, since the oxygen (O2) contained in the air reacts with the hydrocarbon gas and is eliminated, it is possible to avoid supplying oxygen (O2) to the furnace body 11. Alternatively, even if unreacted oxygen (O2) is produced without reacting with hydrocarbon gas, the amount of unreacted oxygen (O2) is small and will be eliminated by reacting with hydrogen (H2) and carbon monoxide (CO), so it does not pose a particular problem.

[0035] (3) Dew point regulator The dew point regulator 13 is connected to the furnace body 11 and adjusts the dew point temperature of the atmospheric gas. By adjusting the dew point temperature, the amount of moisture in the atmospheric gas can be reduced. This reduction in the amount of moisture in the atmospheric gas reduces the amount of carbon dioxide in the atmospheric gas through a water-gas shift reaction. In other words, the dew point regulator 13 of the atmospheric furnace 10 of the present invention adjusts the dew point temperature of the atmospheric gas in order to reduce the amount of moisture in the atmospheric gas in order to reduce the amount of carbon dioxide in the atmospheric gas. Furthermore, the dew point adjuster 13 of the atmosphere furnace 10 of the present invention can be said to be for controlling the CP of the furnace chamber, as it enables adjustment of the concentration of carbon dioxide (CO2) in the atmospheric gas by adjusting the dew point.

[0036] The dew point regulator 13 may include a gas circulation system that circulates the atmospheric gas between it and the furnace body 11, a cooler 32 that cools the atmospheric gas, and a regenerator 34 that regenerates the atmospheric gas (see Figure 1). The gas circulation system includes a supply pipe 31A connected to the furnace body 11 that sends atmospheric gas from the furnace body 11 to the dew point regulator 13, and a return pipe 31B connected to the furnace body 11 that returns atmospheric gas from the dew point regulator 13 to the furnace body 11. The connection points of the supply pipe 31A and return pipe 31B of the gas circulation system to the furnace body 11 are not particularly limited in the case of either a batch-type or continuous-type atmosphere furnace. In addition, the number of connections between the supply pipe 31A and return pipe 31B of the gas circulation system and the furnace body 11 is not particularly limited in the case of either a batch-type or continuous-type atmosphere furnace. That is, in Figure 1, one supply pipe 31A and one return pipe 31B are each connected to the furnace body 11, but it is also possible to configure the system so that two or more of each are connected to the furnace body 11, for example, by branching the supply pipe 31A and the return pipe 31B.

[0037] The cooler 32 is connected to the supply pipe 31A of the gas circulation system and can cool the atmospheric gas sent from the furnace body 11 to the dew point regulator 13. A known cooler or the like can be used for this cooler 32. Typically, the dew point is the temperature at which condensation begins when a gas is cooled, and can be said to indicate the amount of moisture contained in the gas. If the gas being adjusted for dew point is at a high temperature, in most cases the dew point of that gas will also be high, and it will contain a lot of moisture, making it difficult to remove the moisture from the gas. The cooler 32 cools the atmospheric gas sent from the furnace body 11, lowering its temperature and making it easier to lower the dew point. This makes it easier to remove moisture from the atmospheric gas, contributing to improved efficiency in dew point adjustment. Furthermore, when using a desiccant to remove moisture from the atmospheric gas, the desiccant has the ability to release moisture absorbed under high-temperature conditions, meaning its ability to absorb moisture decreases under high-temperature conditions. Therefore, it is preferable to cool the atmospheric gas with the cooler 32.

[0038] In the supply pipe 31A of the gas circulation system, a supply blower 33 can be connected between the cooler 32 and the regenerator 34. A known blower device can be used as the supply blower 33. The supply blower 33 can adjust the flow rate of the atmospheric gas sent to the dew point adjuster 13 (regenerator 34). In particular, the supply blower 33 can be electrically connected to the controller 16, in which case the controller 16 can control the flow rate of the atmospheric gas related to dew point adjustment. Furthermore, when using the supply blower 33, the atmospheric gas can be injected into the regenerator 34 under pressure. That is, when a gas such as the atmospheric gas is pressurized, the saturated water vapor content (the amount of water that can be contained in the gas) decreases. Therefore, when the atmospheric gas is injected into the regenerator 34 under pressure using the supply blower 33, the saturated water vapor content of the atmospheric gas decreases, making it easier to remove water and improving the efficiency of dew point adjustment.

[0039] In the return pipe 31B of the gas circulation system, a surge tank 35 and a return valve 36 can be connected between the regenerator 34 and the furnace body 11. The surge tank 35 can temporarily store the atmospheric gas that has been regenerated by removing moisture in the regenerator 34. The surge tank 35 is not particularly limited in its configuration, etc., as long as it is capable of storing atmospheric gas, and any known tank can be used. The return valve 36 can open and close the return pipe 31B, allowing or restricting the return of atmospheric gas from the dew point regulator 13 to the furnace body 11. Any valve body, such as an electric valve or a solenoid valve, can be used for the return valve 36, as long as it can open and close the return pipe 31B. In addition, the return valve 36 can be electrically connected to the controller 16 using an electric valve or the like, in which case the controller 16 can control the timing of the return of atmospheric gas from the dew point regulator 13 to the furnace body 11, as well as the flow rate of atmospheric gas from the dew point regulator 13 to the furnace body 11.

[0040] The regenerator 34 has regeneration towers 341 and 342 filled with a desiccant. As the atmospheric gas passes through the regeneration towers 341 and 342 of the regenerator 34, moisture is removed from the gas by the desiccant. Dehumidifiers include those that physically adsorb moisture by having pores, etc., and those that chemically absorb moisture by having hygroscopic properties. However, any dehumidifier capable of removing moisture from gas can be used, and there are no particular limitations. Examples of dehumidifiers that physically adsorb moisture include zeolite, activated carbon, silica gel, and alumina gel. Examples of dehumidifiers that chemically absorb moisture include lithium chloride and triethylene glycol. Among these dehumidifiers, those that physically adsorb moisture are preferred because they can release the absorbed moisture by methods such as raising the temperature or creating negative pressure, and their moisture adsorption performance can be easily regenerated.

[0041] The dew point regulator 13 may be equipped with multiple regenerators (regenerator towers), such as the regenerator 34 having multiple regenerator towers. The dew point regulator 13 equipped with multiple regenerators (regenerator towers) can be operated continuously by switching between the multiple regenerators (regenerator towers). In other words, if the dew point regulator 13 is configured to have only one regenerator (regeneration tower), it is necessary to stop operation when the desiccant in that regenerator (regeneration tower) can no longer remove moisture. If the dew point regulator 13 is configured to have multiple regenerators (regeneration towers), even if the desiccant in one regenerator (regeneration tower) can no longer remove moisture, it is possible to continuously remove moisture by switching to another regenerator (regeneration tower) in which the desiccant can remove moisture. For example, in the case of a continuous atmosphere furnace, a configuration in which the dew point regulator 13 has multiple regenerators (regeneration towers) is useful because it can reduce the interruption of heat treatment work caused by the desiccant, allowing the work to continue and improving work efficiency.

[0042] If the dew point regulator 13 is equipped with multiple regenerators (regeneration towers), the regenerator 34 can be switched between an adsorption state in which moisture contained in the atmospheric gas is adsorbed and a standby state in which the adsorbed moisture is desorbed. For example, the atmosphere furnace 10 shown in Figure 1 has a dew point regulator 13 equipped with two regenerators, a first regeneration tower 341 and a second regeneration tower 342. In the state shown in Figure 1, the dew point regulator 13 has the first regeneration tower 341 in an adsorption state and the second regeneration tower 342 in a standby state, with the first regeneration tower 341 removing moisture from the atmospheric gas, and the second regeneration tower 342 regenerating the desiccant by desorbing the adsorbed moisture.

[0043] Specifically, the multiple regenerators (first regeneration tower 341 and second regeneration tower 342) are each connected via a first switching valve 34A to the supply pipe 31A (or supply blower 33) of the gas circulation system, which is on the upstream side in the flow direction of the atmospheric gas in the dew point regulator 13. Furthermore, the multiple regenerators (first regeneration tower 341 and second regeneration tower 342) are each connected via a second switching valve 34B to the return pipe 31B (or surge tank 35) of the gas circulation system that is downstream in the flow direction of the atmospheric gas in the dew point regulator 13. Multiple regenerators (first regeneration tower 341 and second regeneration tower 342) are configured to allow atmospheric gas flow between them and the gas circulation system (supply pipe 31A and return pipe 31B) by switching the first switching valve 34A and the second switching valve 34B, with the one that allows this flow being placed in an adsorption state (first regeneration tower 341 in the case of Figure 1). Furthermore, in the case of Figure 1, the second regeneration tower 342 is placed in a standby state when the flow of atmospheric gas between the regeneration towers (first regeneration tower 341 and second regeneration tower 342) and the gas circulation system (supply pipe 31A and return pipe 31B) is restricted by switching the first switching valve 34A and the second switching valve 34B.

[0044] As shown in Figure 1, multiple regenerators (first regeneration tower 341 and second regeneration tower 342) are connected to the discharge system 343 via a third switching valve 34C, downstream of the flow direction of the atmospheric gas in the dew point regulator 13. The discharge system 343 is connected to a discharge valve 37 and a discharge blower 38. The discharge valve 37 opens and closes the discharge system 343. The discharge blower 38, when the discharge system 343 is opened by the discharge valve 37, exhausts air from inside the regenerator (first regeneration tower 341 and second regeneration tower 342) to the outside via the discharge system 343, thereby creating negative pressure inside the regenerator (first regeneration tower 341 and second regeneration tower 342). Furthermore, multiple regenerators (first regeneration tower 341 and second regeneration tower 342) are each connected to a pressure restoration system 344, and a pressure restoration valve 345 that opens and closes the pressure restoration system 344 is connected to this pressure restoration system 344.

[0045] The regenerator (second regeneration tower 342 in Figure 1), which is in a standby state, is allowed to flow gas with the discharge system 343 by switching the third switching valve 34C. When the discharge system 343 is opened by the discharge valve 37, the discharge blower 38 is operated, which allows gas to be drawn from inside the regenerator (second regeneration tower 342 in Figure 1) that is in a standby state and exhausted to the outside. The discharge system 343 creates negative pressure inside the regenerator by exhausting the gas inside the regenerator (second regeneration tower 342 in the case of Figure 1) which is in a standby state, to the outside. Inside the regenerator, which is under negative pressure, moisture is removed from the desiccant, regenerating the desiccant and enabling further moisture removal. Furthermore, after the desiccant is regenerated, the regenerator (second regeneration tower 342 in the case of Figure 1) is repressurized by opening the repressurization system 344 via the repressurization valve 345.

[0046] In the regenerator (second regeneration tower 342 in Figure 1), which is in standby mode, the atmospheric gas is not flowing, and the gas exhausted to the outside via the discharge system 343 and discharge blower 38 when regenerating the desiccant is essentially only water vapor (moisture). Therefore, the aforementioned dew point regulator 13 ensures that carbon dioxide is not emitted outside the furnace even during the regeneration of the desiccant in the regenerator, which is in standby mode, thereby reducing carbon dioxide emissions.

[0047] The atmosphere furnace 10 of the present invention can reduce the amount of water in the atmosphere gas by adjusting the dew point temperature of the atmosphere gas using the dew point adjuster 13 described above, and as a result, it can reduce the amount of carbon dioxide in the atmosphere gas through a chemical reaction called the water-gas shift reaction. More specifically, inside the furnace body 11 (furnace chamber), a water-gas shift reaction (hereinafter also referred to as the "shift reaction") occurs in which carbon monoxide and water vapor in the atmospheric gas are used as reactants, and carbon dioxide and hydrogen are purified from them as products. Normally, the shift reaction inside the furnace body 11 (furnace chamber) reaches an equilibrium state. The relationship of the shift reaction in this equilibrium state is shown in Chemical Formula 1.

[0048] [ka] However, in formula 1, "CO", "H2O", "H2", and "CO2" represent the concentration or partial pressure of each gas, respectively, and "K" represents the equilibrium constant.

[0049] In equation 1, the equilibrium constant K is a value determined by the temperature (furnace temperature). As shown in equation 1, in a shift reaction, if the amount of H2O in the numerator decreases, the amount of CO2 in the denominator must also decrease. More specifically, inside the furnace body 11 (furnace chamber), when the amount of water vapor (H2O), which is on the reactant side, decreases, a reverse shift reaction occurs in an attempt to maintain equilibrium, where the reaction shifts from the product side to the reactant side (see Chemical Formula 2). Due to this reverse shift reaction, inside the furnace body 11 (furnace chamber), the amount of carbon dioxide (CO2) also decreases as the amount of water vapor (H2O) decreases.

[0050] [ka]

[0051] In other words, the atmospheric furnace 10 of the present invention can reduce the amount of carbon dioxide in the atmospheric gas by removing moisture (water vapor) from the atmospheric gas using the dew point adjuster 13, thereby generating a reverse shift reaction inside the furnace body 11. In other words, the atmospheric furnace 10 of the present invention reduces carbon dioxide not by physical means such as filters or adsorbents, but by chemical means utilizing a reverse shift reaction.

[0052] In the above-mentioned shift reaction, a reverse shift reaction is more likely to occur in an atmosphere of about 650°C. Therefore, from the viewpoint of suitably generating a reverse shift reaction, it is preferable that the lower limit of the furnace temperature in the part of the furnace body 11 where the atmospheric gas from which moisture has been removed using the dew point adjuster 13 is returned (furnace chamber) be 650°C or higher. More preferably, the lower limit of the furnace temperature in this part (furnace chamber) is 670°C or higher, even more preferably 690°C or higher, and particularly preferably 700°C or higher.

[0053] (4) Analyzers and dew point meters The analyzer 14 is used to analyze the CO concentration and CO2 concentration inside the furnace body 11. The analyzer 14 is electrically connected to the controller 16 (see Figure 1), and can input information related to the analyzed CO concentration and CO2 concentration into the controller 16. The analyzer 14 is not particularly limited in its configuration, as long as it is capable of analyzing the CO concentration and CO2 concentration in the furnace chamber. For example, the analyzer 14 may be equipped with a measuring instrument (not shown) for measuring the CO concentration and CO2 concentration inside the furnace body 11. Specifically, examples of measuring instruments include sensors such as CO sensors and CO2 sensors.

[0054] In the atmospheric furnace 10 of this invention, the carbon potential (hereinafter abbreviated as "CP"), which indicates the carbon concentration (carbon equivalent) of the atmosphere inside the furnace body 11, is controlled to be suitable for heat treatment of the workpiece. In order to control this CP, it is necessary to determine the measured value of CP inside the furnace body 11. The analyzer 14 is equipped with a calculation means in the controller 16 for determining the measured value of CP, and it has a function to analyze the CO concentration and CO2 concentration during heat treatment. Specifically, the analyzer 14 can analyze the CO concentration and CO2 concentration inside the furnace body 11 continuously or at regular intervals. The CO concentration and CO2 concentration information analyzed by the analyzer 14 is input to the controller 16 and used to calculate the measured value of CP.

[0055] In batch-type and continuous-type atmosphere furnaces 10, the mounting position of the analyzer 14 on the furnace body 11 is not particularly limited, as long as the CO concentration and CO2 concentration inside the furnace body 11 can be measured. In the case of a continuous atmosphere furnace 10, from the standpoint of controlling the CP (Cooling Pressure), the analyzer 14 can be installed in each of two or more furnace chambers selected from among multiple furnace chambers such as a heating chamber, a soaking chamber, and a slow cooling chamber. In other words, each furnace chamber, such as the heating chamber, soaking chamber, and slow cooling chamber, has a different optimal CP (Coefficient of Processing). Therefore, from the standpoint of controlling the CP, it is preferable to install analyzers 14 in each of two or more furnace chambers selected from among the multiple furnace chambers to monitor and manage the CO concentration and CO2 concentration. Among the multiple furnace chambers, the heating chamber and slow cooling chamber are particularly preferred as the furnace chambers to which the analyzers 14 are installed.

[0056] The dew point meter 15 is used to measure the dew point temperature of the atmospheric gas inside the furnace body 11. The dew point meter 15 is electrically connected to the controller 16 (see Figure 1), and can input information related to the dew point temperature of the atmospheric gas inside the furnace body 11 that it has measured into the controller 16. The dew point meter 15 is not particularly limited in its configuration, etc., as long as it is capable of measuring the dew point temperature of the atmospheric gas inside the furnace body 11; any known dew point meter can be used.

[0057] The atmospheric furnace 10 of this invention can reduce the amount of carbon dioxide in the atmospheric gas by removing moisture (water vapor) from the atmospheric gas. In other words, by changing the amount of moisture (dew point temperature) in the atmospheric gas, the CO2 concentration inside the furnace body 11 (furnace chamber) can be adjusted, and the CP can be controlled based on this adjustment of CO2 concentration. Therefore, measuring the dew point temperature is necessary to control the CP by adjusting the CO2 concentration. The dew point meter 15 has the function of measuring the dew point temperature and inputting it to the controller 16. Based on the dew point temperature input from the dew point meter 15, the controller 16 can control the CP by adjusting the CO2 concentration. Specifically, the dew point meter 15 can measure the dew point temperature inside the furnace body 11 continuously or at regular intervals. The dew point temperature information measured by the dew point meter 15 is input to the controller 16 and used to control the CP by adjusting the CO2 concentration.

[0058] In batch-type and continuous-type atmosphere furnaces 10, the mounting position of the dew point meter 15 on the furnace body 11 is not particularly limited, as long as the dew point temperature of the atmospheric gas inside the furnace body 11 can be measured. In a continuous atmosphere furnace 10, the mounting position of the dew point meter 15 on the furnace body 11 is preferably in each furnace chamber, such as the heating chamber, soaking chamber, and slow cooling chamber, based on the viewpoint of controlling the CP of multiple furnace chambers. In other words, in the case of a continuous atmosphere furnace 10, it is preferable to install the dew point meter 15 in each furnace chamber, such as the heating chamber, soaking chamber, and slow cooling chamber, in order to perform CP control in multiple furnace chambers such as the heating chamber, soaking chamber, and slow cooling chamber.

[0059] (5) Purge device In an atmosphere furnace 10, if air originating from the outside air, particularly oxygen (O2) contained in the air, remains in the furnace chamber of the furnace body 11, problems such as abnormal combustion occurring when supplying an atmospheric gas (for example, an endothermic modification gas) to the furnace chamber, or oxidation of the workpiece during heat treatment, are likely to occur. For this reason, the atmosphere furnace 10 may be equipped with a purging device that purges the inside of the furnace chamber at the start and end of heat treatment. Here, purging is the process of exhausting gases from inside the furnace chamber, such as oxygen (O2), to the outside of the furnace by supplying and filling the furnace chamber with an inert gas as a purge gas. In other words, the purging device supplies an inert gas to the furnace chamber and purges the furnace chamber, thereby making the atmosphere inside the furnace chamber suitable for heat treatment. The inert gas is not particularly limited as long as it is a gas that does not affect the material used on the object being treated during heat treatment, that is, a gas that is inert to the material used on the object being treated. Examples of inert gases include nitrogen (N2) gas, helium gas, neon gas, argon gas, krypton gas, xenon gas, radon gas, and other noble gases, and nitrogen (N2) gas can usually be used.

[0060] The purging device may include a supply unit that supplies inert gas to the furnace chamber and a discharge unit that exhausts gas from the furnace chamber. The supply unit of the purge device is not particularly limited in its configuration, as long as it can supply inert gas to the furnace chamber. The discharge section of the purge device is not particularly limited in its configuration, as long as it can exhaust gases such as oxygen (O2) and inert gases used for purging from inside the furnace chamber.

[0061] Specifically, the supply unit of the purge device may include a purge gas supply system 19A connected to the furnace body 11, an on / off valve 19B connected to the purge gas supply system 19A, and a purge gas supplier 19C connected to the furnace body 11 via the purge gas supply system 19A (see Figure 1). The purge gas supply system 19A is for supplying inert gas as purge gas to the inside of the furnace chamber. The on / off valve 19B is for opening and closing the purge gas supply system 19A. The purge gas supplier 19C is for supplying inert gas as purge gas to the purge gas supply system 19A. Specific examples include a tank or cylinder for storing inert gas, a generator for producing inert gas, or a filter for capturing nitrogen (N2), which is an inert gas, from the air.

[0062] Specifically, the discharge section of the purge device can include a release system 18 connected to the furnace body 11 and a release valve 18A connected to the release system 18 for opening and closing the release system 18 (see Figure 1). The release system 18 is for venting gas from inside the reactor chamber to the outside of the reactor. Any release valve 18A that can open and close the release system 18 can be used. Specific examples include valve bodies such as check valves, motorized valves, and solenoid valves, as well as pressure regulating valves and dampers that open and close at a predetermined operating pressure. When a motorized valve is used for the release valve 18A, it can be electrically connected to the controller 16, allowing the controller 16 to control its opening and closing operation (see Figure 1). When the opening and closing operation of the release valve 18A is controlled by the controller 16, the amount of gas discharged outside the furnace can be controlled.

[0063] The purging device described above can also be used as a furnace pressure regulator to adjust the pressure inside the furnace body 11 (hereinafter referred to as "furnace pressure"). When the furnace pressure in the furnace body 11 is low, the supply unit of the purge device can increase the furnace pressure by opening the purge gas supply system 19A with the on / off valve 19B and supplying inert gas to the furnace chamber from the purge gas supplier 19C via the purge gas supply system 19A. When the furnace pressure in the furnace body 11 is high, the discharge section of the purge device opens the release system 18 with the release valve 18A, and the gas inside the furnace chamber is discharged to the outside of the furnace through the release system 18, thereby lowering the furnace pressure. As described above, when a purge device is used as a furnace pressure regulator, the furnace pressure in the furnace chamber can be adjusted without using an atmospheric gas (endothermic modified gas). This reduces the amount of atmospheric gas (RX gas) used in heat treatment, and by reducing the amount of atmospheric gas (RX gas) used, carbon dioxide emissions can be reduced.

[0064] (6) Controller The controller 16 is used to control the atmosphere inside the furnace body 11 (furnace chamber) to a state suitable for heat treatment, and is primarily used to control the atmospheric pressure (CP). More specifically, the controller 16 is connected to the dew point adjuster 13, analyzer 14, and dew point meter 15, and controls them to lower the dew point temperature of the atmospheric gas and reduce the CO2 concentration in the furnace chamber. Based on the reduction in CO2 concentration, the controller 16 can control the CP of the atmosphere in the furnace chamber of the furnace body 11.

[0065] The controller 16 is electrically connected to the analyzer 14 and can obtain information on the CO concentration and CO2 concentration inside the furnace body 11 (furnace chamber) as analyzed by the analyzer 14. The controller 16 is equipped with a calculation means that calculates the measured value of the CP of the atmosphere inside the furnace body 11 (furnace chamber) based on the CO concentration and CO2 concentration obtained from the analyzer 15.

[0066] The controller 16 is electrically connected to the supply blower 33 and return valve 36 of the dew point adjuster 13, and can operate the supply blower 33 and return valve 36. The controller 16 includes a first CP control means that controls the CO2 concentration inside the furnace chamber of the furnace body 11 by operating the supply blower 33 and return valve 36 of the dew point adjuster 13 so that the CP inside the furnace chamber of the furnace body 11 becomes a preset value according to the heat treatment.

[0067] The controller 16 is electrically connected to the air adjustment valve 214 and the raw material adjustment valve 215 of the gas generator 21, and can operate the air adjustment valve 214 and the raw material adjustment valve 215. The controller 16 may be equipped with a second CP control means that controls the CP by operating the air adjustment valve 214 and raw material adjustment valve 215 of the gas generator 21 to adjust the CO2 concentration in the atmospheric gas so that the CP inside the furnace body 11 (furnace chamber) becomes a preset value according to the heat treatment.

[0068] Specifically, the controller 16 incorporates a computer that includes an arithmetic processing unit such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit), and a storage area such as an HDD, SSD, or ROM. The above-mentioned calculation means, first CP control means, and second CP control means are stored as a program in the memory area of ​​the controller 16. Furthermore, CP suitable for heat treatment is stored in the memory area of ​​the controller 16 as a preset CP setting value. The controller 16 can control the CP by adjusting the CO2 concentration inside the reactor body 11 (furnace chamber) by having the computer execute calculation means, first CP control means, and second CP control means as programs stored in the memory area based on the CP setting value stored in the memory area.

[0069] The controller 16 may be equipped with furnace pressure control means that controls the furnace pressure so that the furnace pressure inside the furnace body 11 (furnace chamber) is suitable for heat treatment. Here, changes in furnace pressure can cause problems such as condensation and blockage in the gas supply system 12 and the supply pipe 31A and return pipe 31B of the gas circulation system. Therefore, it is desirable to implement furnace pressure control in order to suppress changes in furnace pressure.

[0070] The controller 16 is electrically connected to the first control valve 22 of the gas supply system 12 and can operate the first control valve 22. The furnace pressure control means can control the furnace pressure by operating the first adjustment valve 22 and adjusting the amount of atmospheric gas supplied from the gas generator 21 to the furnace body 11. Regarding the furnace pressure control means, the furnace body 11 can be equipped with a furnace pressure gauge 17 for measuring the furnace pressure inside (furnace chamber), and the furnace pressure gauge 17 can be electrically connected to the controller 16 (see Figure 1). The furnace pressure gauge 17 is not particularly limited in type, etc., as long as it is capable of measuring furnace pressure, and a pressure sensor or the like can be used. Furthermore, the controller 16 can store a furnace pressure suitable for heat treatment as a preset pressure in its memory area.

[0071] The furnace pressure control means compares the furnace pressure obtained from the furnace pressure gauge 17 with a preset pressure, and adjusts the amount of atmospheric gas supplied from the gas generator 21 to the furnace body 11 so that the furnace pressure becomes the preset pressure, thereby adjusting the furnace pressure. For example, if the furnace pressure is lower than the set pressure, the furnace pressure control means increases the amount of atmospheric gas supplied from the gas generator 21 to the furnace body 11 to raise the furnace pressure. Conversely, if the furnace pressure is higher than the set pressure, the furnace pressure control means decreases the amount of atmospheric gas supplied from the gas generator 21 to the furnace body 11 to lower the furnace pressure.

[0072] Furthermore, when adjusting the supply amount of atmospheric gas for furnace pressure control, the CO2 concentration and CP (PF) inside the furnace body 11 (furnace chamber) may fluctuate. For this reason, if furnace pressure control is to be performed without fluctuating the CO2 concentration or CP (PF), the aforementioned purge device can be used as a furnace pressure regulator, and the supply amount of inert gas can be adjusted for furnace pressure control. Furthermore, when the aforementioned purge device is used as a furnace pressure regulator for furnace pressure control, if the furnace pressure is abnormally higher than the set pressure, the furnace pressure can be lowered by using the discharge section of the purge device to exhaust the gas from inside the furnace body 11 (furnace chamber) to the outside of the furnace. In particular, the atmosphere furnace of the present invention uses a dew point adjuster 13 and a first CP control means, etc., to adjust the CO2 concentration inside the furnace body 11 (furnace chamber) to a level that is necessary and sufficient to maintain a CP (PF) suitable for heat treatment. Therefore, since the amount of CO2 contained in the gas inside the furnace body 11 (furnace chamber) of the atmosphere furnace of the present invention is less than that of a normal atmosphere furnace, even if the gas inside the furnace body 11 (furnace chamber) is exhausted to the outside of the furnace, the amount of carbon dioxide emissions can be reduced.

[0073] (7) Calculation means The calculation means is a program for calculating the measured value of the CP (Coefficient of Performance) of the atmosphere inside the furnace body 11 (furnace chamber). The calculation means performs calculations to calculate the measured value of the CP (Coefficient of Pressure) of the atmosphere inside the furnace body 11 (furnace chamber) based on the CO concentration and CO2 concentration obtained from the analyzer.

[0074] Specifically, CP can be calculated using the following formula (2). CP=〔(CO concentration) 2 ×Cs〕÷〔(CO2 concentration)×K〕 Formula (2) In equation (2), Cs represents the saturated carbon concentration in the material used for the object. Furthermore, in equation (2), K is the equilibrium constant, and based on the Boudouer reaction shown as "C + CO2 = 2CO", K = (CO concentration) 2 It can be calculated using the formula ÷ [C × (CO2 concentration)] (where C = CP / Cs).

[0075] In equation (2) above, Cs and K are constants. Therefore, the potential factor calculated by equation (3) below (hereinafter also abbreviated as "PF") can be treated as a value equivalent to CP. PF=(CO concentration) 2÷(CO2 concentration)...Equation (3)

[0076] Regarding CP control, from equation (2) or equation (3), CP(PF) can be varied according to the CO2 concentration. Therefore, in CP control, the atmospheric CP (PF) can be controlled by adjusting the CO2 concentration inside the furnace body 11 (furnace chamber) using the first CP control means and / or the second CP control means. Specifically, in CP control, the first CP control means can increase CP (PF) by reducing the CO2 concentration inside the reactor body 11 (furnace chamber). The second CP control means can increase CP(PF) by lowering the CO2 concentration in the RX gas as needed, for example, when the adjustment of the CO2 concentration by the first CP control means is insufficient, and can decrease CP(PF) by increasing the CO2 concentration in the RX gas.

[0077] (8) First CP control means The first CP control means is a program for controlling the CP(PF) of the atmosphere inside the furnace body 11 (furnace chamber). It compares the measured value of CP(PF) with the set value of CP(PF) and controls CP(PF) by operating the dew point adjuster 13 to adjust the CO2 concentration inside the furnace body 11 (furnace chamber) so that the measured value of CP(PF) becomes the set value. In the first CP control means, the measured value of CP(PF) is calculated by the calculation means based on the CO concentration and CO2 concentration obtained from the analyzer 14. In addition, in the first CP control means, the set value of CP(PF) is a value that is set in advance according to the heat treatment. Furthermore, the first CP control means can reduce the CO2 concentration by adjusting the dew point temperature inside the furnace body 11 (furnace chamber) in order to control the CP(PF). This reduction in CO2 concentration contributes to reducing carbon dioxide emissions and also contributes to the regeneration of the atmospheric gas.

[0078] The first CP control means includes a first management means for operating the dew point adjuster 13. This first management means is a program that manages the operation of the dew point adjuster 13 and is included in the first CP control means. The first control means can adjust the amount of atmospheric gas taken in from the furnace body 11 to the dew point adjuster 13 (in other words, the amount of atmospheric gas discharged from the furnace body 11) by operating the supply blower 33 of the dew point adjuster 13, which is electrically connected to the controller 16. The first control means can adjust the amount of atmospheric gas returned from the dew point adjuster 13 to the furnace body 11 (in other words, the amount of atmospheric gas supplied to the furnace body 11) by operating the return valve 36 of the dew point adjuster 13, which is electrically connected to the controller 16.

[0079] The controller 16 is electrically connected to the dew point meter 15 and can obtain information on the dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber) as measured by the dew point meter 15. The first control means can adjust the dew point temperature inside the furnace body 11 (furnace chamber) by adjusting the amount of atmospheric gas taken in from the furnace body 11 and / or the amount of atmospheric gas returned to the furnace body 11, based on information obtained from the dew point meter 15.

[0080] Specifically, the first control means manages the operation of the dew point regulator 13, thereby drawing in atmospheric gas containing a large amount of moisture from inside the furnace body 11 (furnace chamber) to the dew point regulator 13, and returning the atmospheric gas from which moisture has been removed by the dew point regulator 13 back to the furnace body 11, thereby lowering the dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber). Furthermore, the first control means reduces the CO2 concentration by lowering the dew point temperature of the atmospheric gas, thereby causing the aforementioned shift reaction (reverse shift reaction) inside the furnace body 11 (furnace chamber).

[0081] The first CP control means can control the atmospheric CP by adjusting the CO2 concentration inside the furnace body 11 (furnace chamber) using the reduction of CO2 concentration by the first control means. In the first CP control means, the atmospheric gas from which moisture has been removed is returned to the inside of the furnace body 11 (furnace chamber) under the control of the operation of the dew point adjuster 13 by the first control means. The location to which it is returned (furnace chamber) can be a location (furnace chamber) with a temperature (furnace temperature) of 650°C or higher, from the viewpoint of suitably generating a shift reaction (reverse shift reaction).

[0082] In the case of a batch-type atmosphere furnace, it is preferable to perform dew point adjustment at each processing step such as heating, soaking, and slow cooling. For this reason, it is also preferable to return the atmosphere gas from which moisture has been removed to the inside of the furnace body 11 (furnace chamber) at each processing step. In a batch-type atmosphere furnace, it is preferable to return the atmosphere gas, from which moisture has been removed, to the inside of the furnace body 11 (furnace chamber) after adjusting its temperature to match the temperature range of each process, such as heating, soaking, and slow cooling. In batch-type atmosphere furnaces, the furnace temperature during each process, such as heating, soaking, and slow cooling, increases with the progress of the process in the case of heating, decreases with the progress of the process in the case of slow cooling, and remains constant during the process in the case of soaking. However, in all processes, there is a point at which the temperature exceeds 650°C, and at that point, the atmospheric gas from which moisture has been removed can be returned. Alternatively, in order to adjust the temperature of the atmospheric gas returned to the inside of the furnace body 11 (furnace chamber) to the temperature range of each process, a heater that heats the atmospheric gas, such as a heater, a cooler that cools the atmospheric gas, such as a cooler, or a temperature controller that heats and cools the atmospheric gas, such as an air conditioner, can be connected between the dew point adjuster 13 and the furnace body 11.

[0083] In the case of a continuous atmosphere furnace, heating, soaking, and slow cooling are performed in multiple furnace chambers, so it is preferable to return the atmosphere gas, from which moisture has been removed, to a furnace chamber where the furnace temperature is 650°C or higher. Furthermore, in the case of a continuous atmosphere furnace, the number of furnace chambers to which the atmosphere gas from which moisture has been removed is limited to one or two or more, as long as the furnace temperature is 650°C or higher. For example, in a continuous atmosphere furnace, if multiple furnace chambers are connected to each other and the atmospheric gas circulates between the multiple furnace chambers, returning the atmospheric gas to one furnace chamber can reduce the amount of moisture (water vapor) in the atmospheric gas throughout the entire interior of the furnace body 11. Alternatively, in the case of a continuous atmosphere furnace, since the CP differs in each furnace chamber such as the heating chamber, soaking chamber, and slow cooling chamber, the configuration allows the atmosphere gas to be returned to each furnace chamber, enabling the CP control of the atmosphere in each chamber to be performed using the first CP control means. In particular, since the CP of the heating chamber and the slow cooling chamber differ significantly, it is useful to control the atmosphere CP of the first CP control means by configuring the system to return the atmosphere gas to the heating chamber and the slow cooling chamber. In a continuous atmosphere furnace, it is preferable to perform CP control using the first CP control means in each of the multiple furnace chambers. In this case, in each furnace chamber, CP control can be performed at each furnace temperature (each processing temperature) while simultaneously lowering the dew point. The multiple furnace chambers are connected to each other, and the atmospheric gas flows back and forth between the multiple furnace chambers. When returning the atmospheric gas to one furnace chamber, measuring instruments are installed in the furnace body 11 to grasp the amount of atmospheric gas entering (IN) and leaving (OUT) in each furnace chamber, making it possible to perform CP control using the first CP control means in each furnace chamber.

[0084] The dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber) that is lowered by the first control means is not particularly limited, but from the viewpoint of suitably generating a shift reaction (reverse shift reaction), it is preferably 0°C or lower as the upper limit. The upper limit of the dew point temperature is more preferably -1°C or lower, even more preferably -3°C or lower, and particularly preferably -5°C or lower. Furthermore, as the dew point temperature of the atmospheric gas decreases, the amount of moisture can be greatly reduced, but the work efficiency related to dew point adjustment deteriorates and the load on the dew point adjuster 13 increases, so the lower limit is preferably -40°C or higher, more preferably -30°C or higher, even more preferably -20°C or higher, and particularly preferably -10°C or higher. The dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber) indicates the amount of moisture in the atmospheric gas. A low dew point temperature means that the amount of moisture in the atmospheric gas is low. For example, in an atmospheric furnace using RX gas, which is a hydrocarbon gas 13A gas used as the raw material, and with a furnace temperature of 720°C, if the dew point temperature is 12°C, the CO2 concentration is 1.1% and the PF is 151. However, if the dew point temperature is 0°C, the CO2 concentration is 0.58% and the PF is 310.

[0085] (9) Second CP control means The second CP control means is a program for controlling the CP(PF) of the atmosphere inside the furnace body 11 (furnace chamber). It compares the measured value of CP(PF) with the set value of CP(PF) and controls CP(PF) by operating the gas generator 21 to adjust the CO2 concentration in the atmospheric gas so that the measured value of CP(PF) becomes the set value. In the second CP control means, the measured value of CP(PF) is calculated by the calculation means based on the CO concentration and CO2 concentration obtained from the analyzer 14. In the first CP control means, the set value of CP(PF) is a value that is set in advance according to the heat treatment. Furthermore, the second CP control means adjusts the CO concentration and CO2 concentration in the atmospheric gas supplied to the inside of the furnace body 11 (furnace chamber) to optimal values ​​so that the CP (PF) of the atmosphere inside the furnace body 11 (furnace chamber) becomes a value suitable for heat treatment. This suppresses the generation of excess CO2, and this adjustment of CO concentration and CO2 concentration contributes to reducing carbon dioxide emissions and further contributes to reducing the amount of atmospheric gas containing CO2 used.

[0086] The second CP control means includes a second management means for operating the gas supply system 12. This second management means is a program that manages the overall operation of the gas supply system 12, including the gas generator 21, and is included in the second CP control means. The second control means can adjust the amount of atmospheric gas (RX gas) supplied to the furnace body 11 by operating the first adjustment valve 22, which is electrically connected to the controller 16. The second control means can adjust the amount of air and / or hydrocarbon gas supplied to the transformer 211 by operating the air adjustment valve 214 and / or raw material adjustment valve 215, which are electrically connected to the controller 16. By adjusting the amount of air and / or hydrocarbon gas supplied to the transformer 211, the second control means can reduce or increase the CO2 concentration in the atmospheric gas (RX gas) obtained in the transformer 211.

[0087] The controller 16 is electrically connected to the analyzer 14 and can obtain information on the CO concentration and CO2 concentration inside the furnace body 11 (furnace chamber) as analyzed by the analyzer 14. The second control means can adjust the CO2 concentration inside the furnace body 11 (furnace chamber) by adjusting the CO2 concentration in the atmospheric gas supplied to the furnace body 11 and the amount supplied to the furnace body 11, based on the information obtained from the analyzer 14.

[0088] Specifically, the second control means controls the operation of the gas generator 21, thereby reducing or increasing the CO2 concentration in the atmospheric gas, and thus fluctuating the CO2 concentration inside the furnace body 11 (furnace chamber). Furthermore, the second control means adjusts the amount of atmospheric gas supplied to the furnace body 11 as needed, thereby fluctuating the CO2 concentration inside the furnace body 11 (furnace chamber). The second CP control means can control the atmospheric CP by adjusting the CO2 concentration inside the furnace body 11 (furnace chamber) using the fluctuations in CO2 concentration caused by the second control means.

[0089] In the case of a batch-type atmosphere furnace, since the heat treatment including heating, soaking, and slow cooling is performed in a single furnace chamber, the second CP control means can be configured to control the furnace temperature and CP in coordination. In other words, in the case of a batch-type atmosphere furnace, the second CP control means may include a third control means for operating the temperature controller. This third control means is a program that manages the operation of the temperature controller. The third control means operates the temperature controller according to the heating, soaking, and slow cooling processes. For example, it raises the furnace temperature during the heating process, maintains the furnace temperature during the soaking process, and lowers the furnace temperature during the slow cooling process. Furthermore, the second CP control means can coordinately control the furnace temperature and CP by utilizing the second and third control means. For example, in the case of heat treatment, CP can be increased as the furnace temperature rises; in the case of soaking treatment, CP (PF) can be maintained along with the furnace temperature; and in the case of slow cooling treatment, CP can be decreased as the furnace temperature decreases.

[0090] The second CP control means adjusts the CO2 concentration in the ambient gas (RX gas), but does not adjust the CP of the ambient gas (RX gas) itself; in practice, the CP of the ambient gas (RX gas) itself is not considered. In other words, the second CP control adjusts the CO2 concentration in the atmospheric gas (RX gas) to control the atmosphere CP of one furnace chamber in the case of a batch-type atmosphere furnace, and to maintain the atmosphere CP of each furnace chamber in the case of a continuous-type atmosphere furnace. This adjustment of the CO2 concentration in the atmospheric gas (RX gas) is necessary to control the atmosphere CP. Essentially, the second CP control performs CP control by adjusting the amount of CO2 supplied to the furnace body, and not by adjusting the CP of the atmospheric gas (RX gas). Furthermore, the second CP control involves adjusting the amount of CO2 supplied to the reactor body during its implementation. This adjustment optimizes the amount of CO2 in the atmospheric gas (RX gas), reducing the amount of CO2 emitted as surplus, thereby reducing carbon dioxide (CO2) emissions.

[0091] [2] Atmosphere control method The present invention relates to an atmosphere control method for controlling the atmosphere in the furnace chamber of the above-mentioned atmosphere furnace, In order to make the atmosphere of the furnace chamber suitable for the heat treatment, the system includes a first control step of managing the operation of the dew point adjuster so that the carbon potential of the furnace chamber, calculated based on the CO concentration and CO2 concentration obtained from the analyzer, becomes a preset value according to the heat treatment. The first control process described above is: A step of taking in the atmospheric gas from the furnace chamber, A step of lowering the dew point temperature of the aforementioned atmospheric gas, The invention is characterized by comprising the step of returning the atmospheric gas, whose dew point temperature has been lowered, to the furnace chamber where the temperature is 650°C or higher, thereby reducing the CO2 concentration in the furnace chamber.

[0092] Furthermore, the atmosphere control method of the present invention is an atmosphere control method for controlling the atmosphere in the furnace chamber of the above-mentioned atmosphere furnace, In order to make the atmosphere of the furnace chamber suitable for the heat treatment, the system includes a first control step of managing the operation of the dew point adjuster and a second control step of managing the operation of the gas supply system, such that the carbon potential of the furnace chamber, calculated based on the CO concentration and CO2 concentration obtained from the analyzer, becomes a preset value according to the heat treatment. The first control step includes taking in the atmospheric gas from the furnace chamber, lowering the dew point temperature of the atmospheric gas, and returning the atmospheric gas, whose temperature has been lowered to the furnace chamber where the temperature is 650°C or higher, in order to reduce the CO2 concentration in the furnace chamber. The second control step is characterized by comprising a step of reducing or increasing the CO2 concentration in the atmospheric gas supplied to the furnace chamber.

[0093] The atmosphere control method of the present invention is a method of controlling the atmosphere inside the furnace body 11 (furnace chamber) in the above-described atmosphere furnace 10 so that the CP inside the furnace body 11 (furnace chamber) becomes a preset value according to the heat treatment. The atmosphere furnace 10 is equipped with a dew point regulator 13 and a controller 16 connected to the furnace body 11, which adjust the dew point temperature of the atmospheric gas (see Figure 1). The dew point regulator 13 can be used to control the atmosphere inside the furnace body 11 (furnace chamber). The atmosphere control method includes a first control step, which is a step in which the operation of the dew point adjuster 13 is controlled by the controller 16.

[0094] Furthermore, the atmosphere furnace 10 is equipped with a gas supply system 12 connected to the furnace body 11 to supply atmospheric gas to the furnace chamber (see Figure 1), and the gas supply system 12, including the gas generator 21, can be used to control the atmosphere inside the furnace body 11 (furnace chamber). The atmosphere control method includes a second control step, which is a process in which the controller 16 manages the operation of the gas supply system 12, including the gas generator 21. Furthermore, the atmosphere control method may include a furnace pressure control step in which the CP (PF) inside the furnace body 11 (furnace chamber) of the atmosphere furnace 10 is set to a set value, and then the furnace pressure is controlled. The following describes the various processes involved in the atmosphere control method.

[0095] (1) First management process The first control process is the process of managing the operation of the dew point adjuster 13 using the controller 16. The first control process can be performed by the controller 16 operating the dew point adjuster 13 using the first control means (program) of the first CP control means (program) provided in the controller 16.

[0096] Figure 2 is a flowchart showing a specific example of the first control process. The first control process comprises the following steps: Process of introducing atmospheric gas (S11). Step (S12) to lower the dew point temperature. The process of returning the atmospheric gas (S13). A step (S14) to determine whether the dew point temperature is 0°C or lower. Step (S15) to determine if CP is at the set value.

[0097] In step (S11), the controller 16 operates the supply blower 33 of the dew point regulator 13, drawing in atmospheric gas from inside the furnace body 11 (furnace chamber) to the dew point regulator 13 via the supply pipe 31A of the gas circulation system. In step (S11), the atmospheric gas drawn into the dew point regulator 13 is cooled in the cooler 32 and then injected under pressure into the regenerator 34. In step (S12), the dew point temperature of the atmospheric gas taken into the dew point regulator 13 is lowered. Specifically, the atmospheric gas injected into the regenerator 34 passes through the inside of the regenerator (first regeneration tower 341 in the state shown in Figure 1) which is in an adsorption state. As it passes through, the moisture (water vapor) contained in the gas is adsorbed and removed by the desiccant, thereby lowering the dew point temperature. The atmospheric gas with the lowered dew point temperature is then temporarily stored in the surge tank 35.

[0098] In step (S13), the controller 16 operates the return valve 36 of the dew point regulator 13, returning the atmospheric gas from the dew point regulator 13 to the inside of the furnace body 11 (furnace chamber) via the return pipe 31B of the gas circulation system. As the atmospheric gas returned from the dew point regulator 13 has a lower dew point temperature and a lower moisture content, the dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber) decreases. Furthermore, in step (S13), the atmospheric gas whose dew point temperature has been lowered by the dew point regulator 13 is returned to the furnace chamber where the temperature is 650°C or higher. This is because the reverse shift reaction occurs favorably in an atmosphere with a temperature of 650°C or higher. In other words, in furnace chambers with temperatures above 650°C, the amount of moisture (water vapor) in the atmospheric gas decreases when the atmospheric gas, which has a lowered dew point, is returned. This triggers a reverse shift reaction in which carbon dioxide and hydrogen in the atmospheric gas are purified into carbon monoxide and water vapor, in an attempt to maintain chemical equilibrium in the atmosphere. As a result, the amount of carbon dioxide in the atmospheric gas decreases, which contributes to a reduction in carbon dioxide emissions.

[0099] In step (S14), it is determined whether the dew point temperature inside the furnace body 11 (furnace chamber) is 0°C or lower based on measurements by the dew point meter 15. Step (S14) determines, based on the dew point temperature, whether the atmosphere inside the furnace chamber, from which the atmospheric gas has been returned from the dew point regulator 13, is suitable for generating a shift reaction (reverse shift reaction). The dew point temperature can be set to 0°C or lower from the viewpoint of suitably generating a shift reaction (reverse shift reaction). If, in step (S14), it is determined that the dew point temperature is not below 0°C (S14; no), step (S13) is repeated, and the dew point temperature inside the furnace body 11 (furnace chamber) continues to decrease by returning the atmospheric gas from the dew point regulator 13. If it is determined in step (S14) that the dew point temperature is 0°C or lower (S14; yes), then step (S15) is executed.

[0100] In step (S15), it is determined whether the CP is at the set value based on the measured CP values ​​calculated from the CO concentration and CO2 concentration obtained from the analyzer 14. If it is determined in process (S15) that CP is at the set value (S15; yes), the first control process is terminated. If it is determined in step (S15) that CP is not the set value (S15; no), steps (S11) to (S14) are executed repeatedly. In other words, the first control process involves sending atmospheric gas from the inside of the furnace body 11 (furnace chamber) to the dew point adjuster 13, removing moisture from the atmospheric gas, and returning it to the inside of the furnace body 11 (furnace chamber). This continuously generates a shift reaction (reverse shift reaction) inside the furnace body 11 (furnace chamber), adjusting the CO2 concentration and setting the CP to the set value.

[0101] Furthermore, in the first control step, the CO2 concentration can be reduced by a shift reaction (reverse shift reaction). For this reason, it is preferable to use the first control step to control CP primarily when increasing CP. Furthermore, the heat treatment of the workpiece tends to cause a decrease in CO concentration and an increase in CO2 concentration as the treatment progresses, which in turn causes a decrease in CO concentration. Therefore, to suppress the decrease in CO concentration, an atmospheric gas (RX gas) is continuously supplied to the inside of the furnace body 11 (furnace chamber) during the treatment. In contrast, the present invention performs a so-called "regeneration treatment of the atmospheric gas (RX gas)" by removing moisture from the atmospheric gas using a dew point regulator 13, thereby generating a shift reaction (reverse shift reaction) inside the furnace body 11 (furnace chamber), increasing the CO concentration and decreasing the CO2 concentration. As a result, it is possible to reduce the amount of atmospheric gas (RX gas) used, reduce the amount of carbon dioxide in the atmospheric gas (RX gas), and reduce CO2 emissions.

[0102] (2)Second control process The second control process is the process of managing the operation of the gas supply system 12 using the controller 16. The second management process can be executed by the controller 16 using the second management means (program) of the second CP control means (program) provided in the controller 16, and by the controller 16 operating the gas supply system 12, including the gas generator 21.

[0103] Figure 3 is a flowchart showing a specific example of the second control process. The second control process comprises the following steps: Process of supplying atmospheric gas (S21). Process of calculating and analyzing CP (S22). The process of determining whether CP is at the set value (S23). A process (S24) to reduce or increase the CO2 concentration in the gas.

[0104] In process (S21), the controller 16 operates the air adjustment valve 214 and the raw material adjustment valve 215 of the gas generator 21 to generate atmospheric gas (RX gas) in the transformer 211, and also operates the first adjustment valve 22 to supply the atmospheric gas (RX gas) to the inside of the furnace body 11 (furnace chamber). In process (S22), the CO concentration and CO2 concentration inside the furnace body 11 (furnace chamber) are measured by the analyzer 14, and the CP is calculated based on these measurements and analyzed as an actual measured value of CP.

[0105] In process (S23), based on the analysis of the measured value of CP in process (S22), it is determined whether CP is at the set value. If it is determined in process (S23) that CP is at the set value (S23; yes), the second control process is terminated. If it is determined in step (S23) that CP is not the set value (S23; no), then step (S24) is executed. In step (S24), the CO2 concentration in the atmospheric gas (RX gas) generated in the transformer 211 is reduced or increased by operating the air adjustment valve 214 and the raw material adjustment valve 215. After process (S24), processes (S22) and (S23) are repeated until CP reaches the set value.

[0106] In other words, the second control process operates the gas supply system 12, including the gas generator 21, to adjust the CO concentration and CO2 concentration in the atmospheric gas (RX gas) supplied to the inside of the furnace body 11 (furnace chamber), thereby setting the CP to a set value. Typically, in the second control process, the amount of hydrocarbon gas supplied to the transformer 211 is kept constant, and the amount of air supplied is increased or decreased, which allows for optimal adjustment of the CO2 concentration in the atmospheric gas (RX gas). The second control process then adjusts the CO2 concentration in the atmospheric gas (RX gas) to an appropriate level, thereby suppressing the generation of excess CO2 and contributing to the reduction of carbon dioxide emissions.

[0107] In this invention, since the first control step essentially regenerates the atmospheric gas (RX gas), the second control step assists the first control step, enabling appropriate adjustment of the CO2 concentration in the regenerated atmospheric gas (RX gas). For example, in the case of a batch-type atmosphere furnace, a transient period may occur in which the CO2 concentration in the furnace chamber changes moment by moment. In such cases, it is necessary to finely adjust and control the atmospheric pressure (CP) by increasing and / or decreasing the CO2 concentration. Therefore, it is preferable to control the CP using a second control process together with the first control process.

[0108] (3) Furnace pressure control process The above atmosphere control method may include a furnace pressure control step that controls the furnace pressure of the atmosphere inside the furnace body 11 (furnace chamber) after setting CP(PF) to a set value when controlling CP using the first and second control steps. The furnace pressure control process can be performed by comparing the furnace pressure (measured value) obtained from the furnace pressure gauge 17 with a preset pressure according to the heat treatment, and adjusting the amount of atmospheric gas (RX gas) supplied to the furnace body 11 so that the furnace pressure (measured value) becomes the preset pressure. Specifically, the furnace pressure control process can be performed in step (S21) of the second control process described above, by the controller 16 operating the first adjustment valve 22 to adjust the supply amount of atmospheric gas (RX gas). Furthermore, since furnace pressure is prone to change during the slow cooling process included in the heat treatment, it is preferable to perform the furnace pressure control process during the slow cooling process. [Industrial applicability]

[0109] This invention is extremely useful from the standpoint of carbon neutrality because it can reduce carbon dioxide emissions in an atmospheric furnace used for heat treatment of materials. [Explanation of symbols]

[0110] 10; Atmosphere furnace, 11; Furnace body, 12; Gas supply system, 13; Dew point regulator, 14; Analyzer, 15; Dew point meter, 16; Controller, 17; Furnace pressure gauge, 18; Release system, 18A; Release valve, 19A; Purge gas supply system, 19B; On / off valve, 19C; Purge gas supplier, 21; Gas generator, 22; First control valve, 211; Transformer, 212; Air supply system, 213; Raw material supply system, 214; Air control valve, 215; Raw material control valve, 31A; supply pipe of the gas circulation system, 31B; return pipe of the gas circulation system, 32; cooler, 33; supply blower, 34; regenerator, 35; surge tank, 36; return valve, 37; discharge valve, 38; discharge blower, 341; first regeneration tower, 342; second regeneration tower, 34A; first switching valve, 34B; second switching valve, 34C; third switching valve, 343; discharge system, 344; pressure restoration system, 345; pressure restoration valve.

Claims

1. CO and CO ２ An atmospheric furnace that heat-treats an object to be treated inside a furnace chamber filled with an atmospheric gas containing the following: A furnace body comprising the aforementioned furnace chamber, A gas supply system connected to the furnace body and supplying the atmospheric gas to the furnace chamber, A dew point regulator connected to the furnace body for adjusting the dew point temperature of the atmospheric gas, CO concentration and CO in the aforementioned furnace chamber ２ An analyzer for analyzing concentration, A dew point meter for measuring the dew point temperature of the atmospheric gas in the furnace chamber, The dew point regulator, the analyzer, and the dew point meter are connected and adjusted to lower the dew point temperature of the atmospheric gas, thereby reducing the CO2 in the furnace chamber. ２ An atmosphere furnace characterized by comprising a controller for controlling the concentration to be reduced.

2. The aforementioned dew point adjuster is A gas circulation system that circulates the atmospheric gas between the furnace body and the system, A cooler for cooling the atmospheric gas supplied from the furnace chamber of the furnace body via the gas circulation system, The atmosphere furnace according to claim 1, further comprising a regenerator that adsorbs and removes moisture contained in the atmosphere gas cooled by the cooler, thereby regenerating the atmosphere gas.

3. The regenerator is switchable between an adsorption state in which it adsorbs moisture contained in the atmospheric gas and a standby state in which it desorbs the adsorbed moisture. The dew point regulator comprises a plurality of the regenerators, The atmosphere furnace according to claim 2, wherein some of the multiple regenerators are in an adsorption state, and the regenerators other than those in the adsorption state are in a standby state.

4. The atmosphere furnace according to claim 1, wherein the aforementioned atmosphere gas is an endothermic modified gas.

5. The atmosphere furnace according to claim 1, wherein the heat treatment includes heating, soaking, and slow cooling.

6. The atmosphere furnace according to claim 1, wherein the controller adjusts the dew point temperature of the atmosphere gas to 0°C or below.

7. The controller is, The CO concentration and CO obtained from the aforementioned analyzer ２ A calculation means for calculating the carbon potential of the reactor chamber based on the concentration, The dew point adjuster is operated so that the carbon potential in the furnace chamber becomes a preset value according to the heat treatment. ２ The atmosphere furnace according to claim 1, further comprising a first CP control means for adjusting the concentration and controlling the carbon potential.

8. The gas supply system includes a gas generator that generates the atmospheric gas from air and hydrocarbon gas. The gas generator is connected to the controller, The controller is, The CO concentration and CO obtained from the aforementioned analyzer ２ A calculation means for calculating the carbon potential of the reactor chamber based on the concentration, The gas generator is operated so that the carbon potential in the atmospheric gas becomes a preset value according to the heat treatment, thereby controlling the CO in the atmospheric gas. ２ The atmosphere furnace according to claim 1, further comprising a second CP control means for adjusting the concentration and controlling the carbon potential.

9. The atmosphere furnace according to claim 1, further comprising a purging device connected to the furnace body for supplying an inert gas to the furnace chamber to purge the inside of the furnace chamber.

10. An atmosphere control method for controlling the atmosphere in the furnace chamber of an atmosphere furnace according to claim 1, In order to make the atmosphere of the furnace chamber suitable for the heat treatment, the CO concentration and CO obtained from the analyzer ２ The system includes a first control step for managing the operation of the dew point adjuster so that the carbon potential of the furnace chamber, calculated based on the concentration, becomes a preset value according to the heat treatment. The first control process is, A step of taking in the atmospheric gas from the furnace chamber, A step of lowering the dew point temperature of the aforementioned atmospheric gas, Return the atmosphere gas with the dew point temperature lowered to the furnace chamber where the temperature is 650 °C or higher to reduce the CO ２ concentration in the furnace chamber, and an atmosphere control method characterized by comprising the step of

11. An atmosphere control method for controlling the atmosphere in the furnace chamber of an atmosphere furnace according to claim 1, In order to make the atmosphere of the furnace chamber suitable for the heat treatment, the CO concentration and CO obtained from the analyzer ２ The system includes a first management step for managing the operation of the dew point adjuster so that the carbon potential of the furnace chamber, calculated based on the concentration, becomes a preset value according to the heat treatment, and a second management step for managing the operation of the gas supply system. The first control step includes taking in the atmospheric gas from the furnace chamber, lowering the dew point temperature of the atmospheric gas, and returning the atmospheric gas with the lowered dew point temperature to the furnace chamber where the temperature is 650°C or higher to reduce CO2 in the furnace chamber. ２ A process for reducing the concentration is included. The second control step involves the CO2 in the atmospheric gas supplied to the furnace chamber. ２ An atmosphere control method characterized by comprising a step of reducing or increasing the concentration.

12. The atmosphere control method according to claim 10 or 11, wherein the first control step is to lower the dew point temperature of the atmosphere gas to 0°C or below.

13. The furnace body is provided with a furnace pressure gauge for measuring the furnace pressure of the atmosphere in the furnace chamber. After setting the carbon potential of the furnace chamber to the set value, the furnace pressure control process is provided to control the furnace pressure in the furnace chamber. The furnace pressure control process is as follows: The atmosphere control method according to claim 10 or 11, further comprising the steps of comparing the furnace pressure obtained from the furnace pressure gauge with a preset pressure according to the heat treatment, and supplying the atmosphere gas to the furnace chamber or exhausting the atmosphere gas from the furnace chamber so that the furnace pressure becomes the preset pressure.

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