Atmosphere furnace and atmosphere control method

Abstract

An atmospheric furnace and an atmosphere control method are provided that can reduce carbon dioxide emissions. [Solution] An atmospheric furnace (10) for heat-treating workpieces inside a furnace chamber filled with atmospheric gas containing CO and CO2, comprising a furnace body (11) with a furnace chamber, a gas supply system (12) connected to the furnace body (11) for supplying atmospheric gas to the furnace chamber, a dew point regulator (13) connected to the furnace body (11) for 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), the analyzer (14) and the dew point meter (15) for adjusting the dew point temperature of the atmospheric gas to lower the CO2 concentration in the furnace chamber.

Description

[Technical Field]

[0001] The present invention relates to an atmosphere furnace for heat-treating a workpiece, and an atmosphere control method for controlling the atmosphere in a furnace chamber of the atmosphere furnace. [Background technology]

[0002] Heat treatment such as annealing of steel or other materials to be treated is usually carried out using an atmospheric furnace filled with atmospheric gas, and the furnace interior containing the materials to be treated is kept in an atmosphere suitable for the heat treatment. Regarding heat treatment using an atmospheric furnace, Patent Documents 1, 2, and 3 disclose an atmosphere control method in which an endothermic converted gas is used as the atmospheric gas and the carbon potential (hereinafter also referred to as "CP"), which indicates the carbon concentration (carbon equivalent) of the atmosphere in the furnace, is controlled by adjusting the amount of endothermic converted gas supplied to the furnace. Note that the endothermic converted gas is a gas produced by reaction from a hydrocarbon gas such as propane, and is a mixed gas containing CO, CO2, H2, etc. Furthermore, CP can be calculated based on the CO2 concentration and CO2 concentration in the atmosphere or gas. Furthermore, Patent Document 4 discloses a method for separating carbon dioxide (CO2) from flue gas using a membrane for the purpose of reducing carbon dioxide (CO2) emissions from furnace exhaust gas, characterized in that the flue gas has a temperature above the dew point curve of water vapor before entering the membrane. Additionally, Patent Document 5 discloses a method for reducing the dew point of the atmospheric gas in a furnace using a dryer that dehumidifies the gas to a dew point of −45° C. or lower, with the aim of improving plating adhesion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-76109 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-76986 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-76986 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-528850 [Patent Document 5] International Publication No. 2013 / 153791 Summary of the Invention [Problem to be solved by the invention]

[0004] During 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-neutral processes, it is desirable to reduce the amount of CO2 emissions, which is a greenhouse gas. The atmosphere control methods disclosed in Patent Documents 1 to 3 control CP by increasing or decreasing the supply amount of endothermic converted gas, which is a mixed gas of CO, CO2, etc. However, because the CO2 concentration in the endothermic converted gas used is kept at a constant value (fixed value), the endothermic converted gas is used inefficiently, such that only CO is used and CO2 is exhausted without being used, resulting in a lot of CO2 being wasted and exhausted. The method disclosed in Patent Document 4 uses a membrane to separate CO2 from the exhaust gas discharged outside the furnace, but in reality it is a technology for capturing CO2 that is about to be discharged outside the furnace, and does not take into consideration the processing or handling of CO2 after separation. The method disclosed in Patent Document 5 is a method for lowering the dew point of the atmospheric gas with the aim of improving plating adhesion, and does not take into consideration the reduction of CO2 emissions.

[0005] The present invention seeks to solve the problems associated with the prior art, and aims to provide an atmosphere furnace and an atmosphere control method that can reduce carbon dioxide emissions. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention is presented below. [1] The atmospheric furnace of the present invention is an atmospheric furnace in which a workpiece is heat-treated inside a furnace chamber filled with an atmospheric gas containing CO and CO, a furnace body including the furnace chamber; a gas supply system connected to the furnace body to supply 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 furnace chamber; a dew point meter that measures the dew point temperature of the atmospheric gas in the furnace chamber; The gist of the present invention is that it includes a controller that is connected to the dew point regulator, the analyzer, and the dew point meter, and that adjusts the dew point temperature of the atmospheric gas to lower the CO2 concentration in the furnace chamber. [2] In the atmosphere furnace of the present invention, The dew point regulator is a gas circulation system for circulating the atmospheric gas between the furnace body and the gas circulation system; a cooler that cools the atmospheric gas sent from the furnace chamber of the furnace body through the gas circulation system; The cooling system may further include a regenerator that adsorbs and removes moisture contained in the atmospheric gas cooled by the cooler to regenerate the atmospheric gas. [3] In the atmosphere 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 includes a plurality of the regenerators, Some of the plurality of regenerators may be in an adsorption state, and the other regenerators may be in a standby state. [4] In the atmosphere furnace of the present invention, The atmospheric gas may be an endothermic converted gas. [5] In the atmosphere furnace of the present invention, The heat treatment may include heating, soaking, and slow cooling. [6] In the atmosphere furnace of the present invention, The controller can adjust the dew point temperature of the ambient gas to drop to 0° C. or below. [7] In the atmosphere furnace of the present invention, The controller a calculation means for calculating the carbon potential of the furnace chamber based on the CO concentration and CO2 concentration obtained from the analyzer; and a first CP control means for controlling the carbon potential by adjusting the CO concentration in the furnace chamber by operating the dew point regulator 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 that generates the atmospheric gas from air and a hydrocarbon gas; the gas generator is connected to the controller; The controller a calculation means for calculating the carbon potential of the furnace chamber based on the CO concentration and CO2 concentration obtained from the analyzer; and second CP control means for controlling the carbon potential by adjusting the CO2 concentration in the atmospheric gas by operating the gas generator 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 may further include a purge device connected to the furnace body and supplying an inert gas to the furnace chamber to purge the inside of the furnace chamber.

[10] The atmosphere control method of the atmospheric furnace of the present invention is an atmosphere control method for controlling the atmosphere in the furnace chamber of the atmospheric furnace described in [1], a first control step of controlling the operation of the dew point regulator 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, in order to make the atmosphere in the furnace chamber suitable for the heat treatment; The first management step includes: taking in the atmospheric gas from the furnace chamber; lowering the dew point temperature of the atmospheric gas; The method also includes a step of returning the atmospheric gas, the dew point of which has been lowered, to the furnace chamber, the temperature of which is 650°C or higher, to reduce the CO2 concentration in the furnace chamber.

[11] The atmosphere control method of the atmospheric furnace of the present invention is an atmosphere control method for controlling the atmosphere in the furnace chamber of the atmospheric furnace described in [1], a first management step of managing the operation of the dew point regulator and a second management step of managing the operation of the gas supply system 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, 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 atmospheric gas from the furnace chamber, a step of lowering the dew point temperature of the atmospheric gas, and a step of returning the atmospheric gas whose dew point temperature has been lowered to the furnace chamber, the temperature of which is 650°C or higher, to reduce the CO2 concentration in the furnace chamber; The second control step includes a step of reducing or increasing a CO2 concentration in the atmospheric gas supplied to the furnace chamber.

[12] In the atmosphere control method of the atmosphere furnace of the present invention, The first control step can lower the dew point temperature of the atmospheric 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; a furnace pressure control step of controlling a furnace pressure in the furnace chamber after setting the carbon potential in the furnace chamber to the set value, The furnace pressure control step includes: The method may include a step of comparing the furnace pressure obtained from the furnace pressure gauge with a set pressure that is preset according to the heat treatment, and supplying the atmospheric gas to the furnace chamber or exhausting the atmospheric gas from the furnace chamber so that the furnace pressure becomes the set pressure. [Effects of the Invention]

[0007] The atmospheric furnace and the atmospheric control method for the atmospheric furnace of the present invention use a dew point regulator to reduce the moisture content in the atmospheric gas, thereby reducing the carbon dioxide content in the atmospheric gas through the water-gas shift reaction, which is a chemical reaction, and thereby reducing the amount of carbon dioxide (CO2) emissions. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an embodiment of an atmospheric furnace according to the present invention. [Figure 2] 3 is a flowchart illustrating an example of a first control step in the atmosphere control method of the present invention. [Figure 3] 4 is a flowchart illustrating an example of a second control step in the atmosphere control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this respect, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some aspects of the present invention may be actually embodied.

[0010] [1] Atmosphere furnace The atmospheric furnace of the present invention is an atmospheric furnace in which a workpiece is heat-treated inside a furnace chamber filled with an atmospheric gas containing CO and CO, a furnace body including the furnace chamber; a gas supply system connected to the furnace body to supply 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 furnace chamber; a dew point meter that measures the dew point temperature of the atmospheric gas in the furnace chamber; and a controller connected to the dew point regulator, the analyzer, and the dew point meter, for adjusting the dew point temperature of the atmospheric gas to lower the CO2 concentration in the furnace chamber.

[0011] FIG. 1 is a block diagram showing an embodiment of an atmosphere furnace according to the present invention. The atmospheric furnace 10 of the present invention is used to perform heat treatment on a workpiece. The heat treatment performed by this atmospheric furnace 10 can include heating, soaking, and slow cooling. That is, the atmospheric furnace 10 can perform three types of heat treatment on the workpiece: heating, soaking, and slow cooling.

[0012] The heat treatment is not particularly limited with respect to the purpose of the treatment, the treatment method, etc. The purposes of treatment include removing strain, removing stress, making the structure uniform, changing properties, etc. Treatment methods include annealing, quenching, tempering, normalizing, etc. As a heat treatment including heating, soaking, and slow cooling, annealing can be mentioned, which is preferably performed on a workpiece made of an iron-based material, with the purpose of removing strain, softening the structure, improving ductility, etc. In addition to the processes of heating, soaking, and slow cooling, the heat treatment can also include processes such as a purging process in which gas inside the furnace chamber is exhausted to the outside of the furnace, a preheating process in which the object is preheated, and a cooling process in which the object is cooled naturally.

[0013] The treatment methods for atmospheric furnaces include a batch type in which heat treatment is intermittently applied to workpieces placed in the furnace, and a continuous type in which heat treatment is continuously applied to workpieces transported through the furnace. In the case of a batch type, the atmosphere furnace 10 can change the temperature conditions for each heat treatment cycle, which has the advantage of being able to handle a wide variety of workpieces, such as being able to heat treat two or more types of workpieces with different iron-based material compositions using the same atmosphere furnace 10. In addition, the batch type atmosphere furnace 10 also has the advantage of being able to simplify the configuration and save space. In the case of the continuous type, the interior of the furnace body 11 of the atmosphere furnace 10 is divided into a plurality of chambers such as a heating chamber, a soaking chamber, and a slow cooling chamber according to the processes included in the heat treatment, such as heating, soaking, and slow cooling, and the plurality of chambers can be adjusted and maintained at the temperature conditions according to each process, which has the advantage of being able to handle mass production of workpieces. In addition, the continuous type atmosphere furnace 10 also has the advantage of being able to shorten the processing time and increase the number of processes per unit time. The atmospheric furnace 10 of the present invention is not particularly limited in terms of the treatment method, and either a continuous type or a batch type can be employed.

[0014] Here, the atmospheric furnace of the present invention can reduce the moisture content in the atmospheric gas by using a dew point regulator, thereby reducing the carbon dioxide content in the atmospheric gas through the water-gas shift reaction. In other words, the atmospheric furnace of the present invention can arbitrarily reduce the 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 that performs heat treatment on a workpiece, arbitrarily reducing the carbon dioxide in the atmospheric gas enables carbon potential control (hereinafter also referred to as "CP control") in the furnace chamber by adjusting the CO2 concentration. That is, the atmosphere furnace of the present invention can reduce the amount of carbon dioxide (CO2) emissions by adjusting the dew point. Furthermore, the atmosphere furnace of the present invention can control the CP of the furnace chamber based on the adjustment of the carbon dioxide (CO2) concentration in the atmosphere gas by adjusting the dew point.

[0015] In the case of a batch-type atmosphere furnace, each process such as heating, soaking, and slow cooling is performed in one furnace chamber of the furnace body 11. The batch-type atmosphere furnace can perform dew point adjustment in each process such as heating, soaking, and slow cooling, based on the viewpoint of controlling the CP of one furnace chamber. In the case of a continuous atmosphere furnace, the interior of the furnace body 11 is divided into multiple furnace chambers corresponding to each process, such as heating, soaking, slow cooling, etc. The continuous atmosphere furnace can perform dew point adjustment in each furnace chamber based on the viewpoint of controlling the CP of the multiple furnace chambers. That is, the optimum temperature (treatment temperature) for each treatment, such as heating, soaking, and slow cooling, included in the heat treatment, is different, and the optimum carbon potential (CP) for each treatment is also different. For this reason, in the case of a batch-type atmosphere furnace, the temperature of one furnace chamber and the atmosphere of CP, etc. are changed and adjusted to suit each process such as heating, soaking, and slow cooling, and dew point adjustment can be performed as CP control regarding the adjustment of the atmosphere in each process such as heating, soaking, and slow cooling. In addition, in the case of a continuous atmosphere furnace, the temperature and atmosphere such as CP of each of multiple furnace chambers, such as the heating chamber where the heating treatment is performed, the soaking chamber where the soaking treatment is performed, and the slow cooling chamber where the slow cooling treatment is performed, are adjusted in each furnace chamber to suit each treatment, and dew point adjustment can be performed as CP control in relation to the adjustment of the atmosphere in each furnace chamber.

[0016] The object to be treated in the atmosphere furnace 10 is not particularly limited in terms of shape, use, material used, etc., as long as it is subject to heat treatment. The shape of the object to be treated may be linear, tubular, columnar, plate-like, rectangular, or the like. Examples of uses for the treated materials include parts for automobiles and devices, and building materials. Examples of materials used for the object to be treated include iron-based materials such as iron and iron alloys such as steel. The iron-based material is not particularly limited as long as it is made of iron (Fe) containing carbon (C). In addition to carbon and iron, the iron-based material can include alloys containing silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), nickel (Ni), chromium (Cr), tungsten (W), vanadium (V), molybdenum (Mo), cobalt (Co), etc. Specific examples of the iron-based material include steels such as ordinary steel, special steel, and cast and forged steel, and irons such as cast iron.

[0017] Each component of the atmosphere furnace 10 will be described below. (1) Furnace body The furnace body 11 is used to actually perform heat treatment on the object to be treated in the atmosphere furnace 10 (see FIG. 1), and includes a furnace chamber (not shown) therein for accommodating the object to be treated. When the treatment method of the atmospheric furnace 10 is a batch type, the number of furnace chambers provided in the furnace body 11 can usually be one. In this case, the workpiece is placed in one furnace chamber of the furnace body 11 and subjected to at least three heat treatments: a heating treatment, a soaking treatment, and a slow cooling treatment. When the treatment method of the atmospheric 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 treatments included in the heat treatment. For example, when the heat treatment includes three treatments, namely, heating, soaking, and slow cooling, the furnace body 11 can be provided with three furnace chambers, namely, a heating chamber, a soaking chamber, and a slow cooling chamber.

[0018] In the case of the continuous type, the workpiece is transported inside the furnace body 11 so as to pass through a plurality of furnace chambers, and is subjected to each treatment included in the heat treatment in each furnace chamber. For example, if the furnace body 11 is equipped with three furnace chambers, a heating chamber, a soaking chamber, and a slow cooling chamber, the workpiece is transported through the heating chamber, the soaking chamber, and the slow cooling chamber in this order, and is subjected to 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, analyzers, etc. to grasp the inflow (IN) and outflow (OUT) of atmospheric gas in each furnace chamber from the viewpoint of CP control.

[0019] The furnace body 11 may be of any material, shape, size, furnace internal volume, heating and cooling method, etc., as long as it is compatible with the processing method of the atmospheric furnace 10. For example, the furnace body 11 may be provided with a furnace chamber for carrying out heat treatments including heating, soaking, and slow cooling, as well as chambers for treatments other than heat treatments, such as a front chamber and a rear chamber. The antechamber can be a chamber in which the object W is kept waiting before being heat-treated, or a chamber in which the object W is preheated before being heat-treated. The rear chamber can be a chamber for storing the object W after heat treatment, or for allowing the object W after heat treatment to cool to room temperature.

[0020] The furnace body 11 may have a temperature regulator for adjusting the temperature of the atmosphere in the furnace chamber (hereinafter also referred to as "furnace temperature"). The temperature regulator is not particularly limited in configuration, type, etc., as long as it is capable of adjusting the furnace temperature. The temperature regulator is preferably one that does not release carbon dioxide contained in the combustion gas or air into the inside of the furnace body, and examples thereof include a burner, heater, heat exchanger, etc. installed in the furnace chamber of the furnace body 11.

[0021] The burner uses gas, oil, or the like as fuel and can raise the temperature inside the furnace body 11 by the combustion heat of the fuel. The heater converts electricity into thermal energy and can use that thermal energy to raise the temperature inside the furnace body 11, and examples of the heater include a resistance heater, an infrared heater, and an induction heater. The heat exchanger is a device that passes a heat medium such as combustion gas or a refrigerant such as air through a tubular heat exchange tube, and is capable of raising or lowering the temperature inside the furnace body 11 through heat exchange. Specific examples of the heat exchanger include a radiant tube burner and a cooling tube.

[0022] By electrically connecting the temperature regulator to the controller 16, the controller 16 can control the temperature increase and decrease operations. In this way, the temperature regulator controlled by the controller 16 can adjust the furnace temperature so that the furnace chamber of the furnace body 11 is at an optimum temperature for heating, soaking, slow cooling, etc. in the heat treatment. In this case, the amount of fuel used to adjust the furnace temperature can be optimized, and wasteful use of fuel, etc. can be avoided. In particular, by keeping the use of fuel, etc. to an appropriate amount, carbon dioxide emissions can also be reduced. The optimum temperature for each of the heating, soaking, and slow cooling processes can be determined in advance depending on the material (e.g., iron-based material, etc.) used for the workpiece, the purpose of the heat treatment (e.g., annealing, etc.), etc. Therefore, the optimum temperature for each of the heating, soaking, and slow cooling processes can be stored in the controller 16 as a preset temperature setting, and the temperature regulator, whose operation is controlled by the controller 16, can adjust the furnace temperature to the set temperature (optimum temperature) corresponding to each process, thereby controlling the temperature of the atmosphere.

[0023] For example, in a heating process, the temperature regulator adjusts the furnace temperature so that the temperature of the workpiece increases 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 regulator adjusts the furnace temperature so that the temperature of the workpiece being treated is maintained within an optimum range for soaking. In the slow cooling process, the temperature regulator adjusts the furnace temperature so that the temperature of the workpiece decreases at a constant rate during the process. The lower limit of the furnace temperature in the slow cooling process can be determined arbitrarily depending on the material of the workpiece to be processed, etc.

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

[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 FIG. 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 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] First adjustment valve 22, air adjustment valve 214, and raw material adjustment valve 215 are not particularly limited in type as long as they can be operated by controller 16 and can open and close the systems to which they are connected, and for example, solenoid valves, motor-operated valves, etc. can be used. Among these, motor-operated valves are preferable for use as first adjustment valve 22, air adjustment valve 214, and raw material adjustment valve 215, because the amount of opening and closing can be adjusted by operation by controller 16. The hydrocarbon gas used as the raw material is not particularly limited, and examples thereof include methane gas, butane gas, and propane gas, and usually propane gas can be used.

[0027] The converter 211 can mix a hydrocarbon gas with air and react the hydrocarbon gas (e.g., propane gas; C3H8) with the oxygen (O2) contained in the air as shown in the following equation (1) 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 moisture (H2O). Therefore, the gas generator 21 having the transformer 211 can generate an endothermic transformed gas (hereinafter also referred to as "RX gas"), which is a mixed gas containing multiple gases such as carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), moisture (H2O), and nitrogen (N2), from air and hydrocarbon gas. The RX gas generated in the gas generator 21 is supplied to the furnace body 11 as atmospheric gas via the gas supply system 12.

[0028] The transformer 211 is not particularly limited in terms of configuration, but may be provided with a catalyst for causing a reaction between air and hydrocarbon gas. A nickel catalyst is usually used as the catalyst, and the catalyst is heated to a high temperature (about 1000 to 1100°C) and the air and hydrocarbon gas are brought into contact with each other to cause a reaction between them. Gas generator 21 is not particularly limited in terms of configuration, and can be configured, for example, such that a blower for supplying air, such as a blower, compressor, or fan, is connected to air supply system 212, or such that a tank or cylinder for storing hydrocarbon gas is connected to 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 the amount of 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 the CO2 concentration is increased by adjusting the supply amounts of air and hydrocarbon gas, the supply amount of air to the transformer 211 is increased and / or the supply amount of hydrocarbon gas is decreased. When the amount of air supplied is increased, the amount of carbon dioxide (CO2) in the RX gas increases accordingly, and the CO2 concentration increases. Also, when the amount of hydrocarbon gas supplied is reduced, the amounts of carbon monoxide (CO) and hydrogen (H2) in the RX gas decrease, and the CO2 concentration in the RX gas increases accordingly.

[0031] When the CO2 concentration is reduced by adjusting the amounts of air and hydrocarbon gas supplied, the amount of air supplied to the transformer 211 is reduced and / or the amount of hydrocarbon gas supplied is increased. When the amount of air supplied is reduced, the amount of carbon dioxide (CO2) in the RX gas decreases accordingly, resulting in a lower CO2 concentration. Also, when the amount of hydrocarbon gas supplied is increased, the amounts of carbon monoxide (CO) and hydrogen (H2) in the RX gas increase, resulting in a lower CO2 concentration in the RX gas.

[0032] In practice, the CO 2 concentration in the RX gas can be easily adjusted by adjusting only the amount of air supplied to the transformer 211. Alternatively, when adjusting the CO2 concentration in the RX gas, or when fine and precise adjustment of the CO2 concentration is required, it is desirable to adjust both the supply amount of air and the supply amount of hydrocarbon gas.

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

[0034] When adjusting the CO2 concentration in the RX gas by adjusting only 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, the oxygen (O2) contained in the air reacts with the hydrocarbon gas and is eliminated, so it is possible to prevent oxygen (O2) from being supplied to the furnace body 11. Alternatively, even if unreacted oxygen (O2) is produced without reacting with the hydrocarbon gas, this is not a particular problem because the amount of unreacted oxygen (O2) is so small that it disappears by reacting with hydrogen (H2) or carbon monoxide (CO).

[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, and the moisture content in the atmospheric gas can be reduced by adjusting the dew point temperature. Such a reduction in the moisture content in the atmospheric gas reduces the amount of carbon dioxide in the atmospheric gas through the water-gas shift reaction. That is, 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 carbon dioxide in the atmospheric gas and to reduce the amount of moisture in the atmospheric gas. Furthermore, the dew point regulator 13 of the atmosphere furnace 10 of the present invention can be said to be for controlling the CP of the furnace chamber, since it enables the adjustment of the concentration of carbon dioxide (CO2) in the atmosphere gas by adjusting the dew point.

[0036] The dew point regulator 13 may include a gas circulation system for circulating the atmospheric gas between the furnace body 11, a cooler 32 for cooling the atmospheric gas, and a regenerator 34 for regenerating the atmospheric gas (see FIG. 1). The gas circulation system includes an outflow pipe 31A connected to the furnace body 11 for sending the atmospheric gas from the furnace body 11 to the dew point regulator 13, and a return pipe 31B connected to the furnace body 11 for returning the atmospheric gas from the dew point regulator 13 to the furnace body 11. The positions at which the supply pipe 31A and return pipe 31B of the gas circulation system are connected to the furnace body 11 are not particularly limited in either the batch type or continuous type atmosphere furnace. Additionally, the number of supply pipes 31A and return pipes 31B of the gas circulation system connected to the furnace body 11 is not particularly limited in either the batch or continuous atmospheric furnace. That is, in Fig. 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 two or more of each to be connected to the furnace body 11, for example, by branching each of the supply pipes 31A and return pipes 31B.

[0037] The cooler 32 is connected to the outgoing 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 gas is cooled, and can be said to indicate the amount of moisture contained in the gas. If the gas to be dew-point adjusted has a high temperature, the dew point of the gas is often also high and the gas contains 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 the temperature and making it easier to lower the dew point, thereby making the atmospheric gas easier to remove moisture from, and contributing to improving the efficiency of dew-point adjustment. When a dehumidifying agent is used to remove moisture from the atmospheric gas, the dehumidifying agent has the ability to release absorbed moisture in a high-temperature atmosphere. In other words, the ability to absorb moisture decreases in a high-temperature atmosphere. Therefore, it is more preferable to cool the atmospheric gas using a cooler 32.

[0038] A supply blower 33 can be connected to the outgoing pipe 31A of the gas circulation system between the cooler 32 and the regenerator 34. The supply blower 33 can be a known blower device. The supply blower 33 can adjust the flow rate of the atmospheric gas sent to the dew point regulator 13 (regenerator 34). In particular, the supply blower 33 can be electrically connected to the controller 16, and in this case, the controller 16 can control the flow rate of the atmospheric gas related to the dew point adjustment. Furthermore, when the supply blower 33 is used, the atmospheric gas can be pressure-fed into the regenerator 34. That is, when a gas such as the atmospheric gas is pressurized, the amount of saturated water vapor (the amount of moisture that can be contained in the gas) decreases. Therefore, when the atmospheric gas is pressure-fed into the regenerator 34 using the supply blower 33, the amount of saturated water vapor in the atmospheric gas decreases, making it easier to remove moisture 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 configuration, etc., as long as it can store atmospheric gas, and a known tank, etc. can be used. The return valve 36 can open and close the return pipe 31B, and can allow or restrict 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. The return valve 36 can also be electrically connected to the controller 16 using an electric valve or the like, and in this case, the controller 16 can control the timing of returning atmospheric gas from the dew point regulator 13 to the furnace body 11, the flow rate of atmospheric gas from the dew point regulator 13 to the furnace body 11, etc.

[0040] The regenerator 34 has regeneration towers 341 and 342 filled with a dehumidifying agent. When the atmospheric gas passes through the inside of the regeneration towers 341 and 342 of the regenerator 34, moisture in the gas is removed by the dehumidifying agent. Examples of dehumidifying agents include those that have pores or the like and thereby physically adsorb moisture, and those that have hygroscopic properties and thereby chemically absorb moisture, but any dehumidifying agent can be used as long as it can remove moisture from gas, and there are no particular limitations on the type. Examples of dehumidifying agents that physically adsorb moisture include zeolite, activated carbon, silica gel, alumina gel, etc. Examples of dehumidifying agents that chemically absorb moisture include lithium chloride, triethylene glycol, etc. Among these dehumidifying agents, those that physically adsorb moisture are preferred because they can release the absorbed moisture by methods such as increasing the temperature or creating a negative pressure, and their moisture adsorption performance can be easily restored.

[0041] The dew point regulator 13 may be provided with a plurality of regenerators (regenerator towers), such as the regenerator 34 having a plurality of regenerator towers. The dew point regulator 13 provided with a plurality of regenerators (regenerator towers) can be operated continuously by switching between the plurality of regenerators (regenerator towers). That is, if the dew point regulator 13 is configured with only one regenerator (regeneration tower), operation must be stopped when the dehumidifying agent in that regenerator (regeneration tower) can no longer remove moisture. If the dew point regulator 13 is configured with multiple regenerators (regeneration towers), even if the dehumidifying agent in one regenerator (regeneration tower) can no longer remove moisture, moisture can be continuously removed by switching to another regenerator (regeneration tower) in which the dehumidifying agent can remove moisture. For example, in the case of a continuous atmosphere furnace, a configuration in which the dew point regulator 13 is configured with multiple regenerators (regeneration towers) is useful because it reduces the need to stop work related to heat treatment due to dehumidifying agents, allowing the work to continue and improving work efficiency.

[0042] When the dew point regulator 13 is equipped with multiple regenerators (regenerator towers), the regenerator 34 can be freely switched between an adsorption state in which the moisture contained in the atmospheric gas is adsorbed and a standby state in which the adsorbed moisture is desorbed. For example, the atmospheric furnace 10 shown in FIG. 1 has a dew point regulator 13 equipped with two regenerators, a first regenerator 341 and a second regenerator 342. In the state shown in FIG. 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 ambient gas and the second regeneration tower 342 desorbing the adsorbed moisture to regenerate the dehumidifying agent.

[0043] Specifically, the multiple regenerators (first regenerator 341 and second regenerator 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 upstream in the flow direction of the ambient gas in the dew point regulator 13. In addition, 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, which is downstream in the flow direction of the ambient gas in the dew point regulator 13. Of the multiple regenerators (first regeneration tower 341 and second regeneration tower 342), the one (in the case of Figure 1, first regeneration tower 341) that allows atmospheric gas to flow between it and the gas circulation system (outlet pipe 31A and return pipe 31B) is put into an adsorption state by switching the first switching valve 34A and the second switching valve 34B. In addition, among the multiple regenerators (first regenerator 341 and second regenerator 342), one (in the case of Figure 1, second regenerator 342) is placed in a standby state in which the flow of atmospheric gas between it and the gas circulation system (outlet pipe 31A and return pipe 31B) is regulated by switching operation of first switching valve 34A and second switching valve 34B.

[0044] As shown in FIG. 1, the multiple regenerators (first regenerator 341 and second regenerator 342) are each connected to a release system 343 via a third switching valve 34C downstream of the dew point regulator 13 in the flow direction of the ambient gas. 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 exhausts air from the inside of the regenerators (the first regenerator 341 and the second regenerator 342) to the outside via the discharge system 343 while the discharge valve 37 opens the discharge system 343, thereby creating a negative pressure inside the regenerators (the first regenerator 341 and the second regenerator 342). Furthermore, the multiple regenerators (first regenerator 341 and second regenerator 342) are each connected to a pressure recovery system 344, and a pressure recovery valve 345 that opens and closes the pressure recovery system 344 is connected to the pressure recovery system 344.

[0045] By switching the third switching valve 34C, the regenerator (second regenerator 342 in the case of FIG. 1) placed in a standby state is allowed to have gas flow between it and the release system 343. With the release valve 37 open, the release system 343 can suck gas from inside the regenerator (second regenerator 342 in the case of FIG. 1) placed in a standby state and exhaust it to the outside by operating the release blower 38. The release system 343 exhausts the gas inside the regenerator (second regenerator 342 in the case of FIG. 1) that is on standby to the outside, thereby creating a negative pressure inside the regenerator. Inside the regenerator under negative pressure, moisture is desorbed from the dehumidifying agent, and the dehumidifying agent is regenerated, making it possible to remove moisture again. After the dehumidifying agent is regenerated, the regenerator (second regeneration tower 342 in the case of FIG. 1) has pressure recovery valve 345 to open pressure recovery system 344, thereby restoring pressure.

[0046] In the regenerator in the standby state (in the case of Figure 1, the second regeneration tower 342), the atmospheric gas is not flowing, and when the dehumidifying agent is regenerated, the gas discharged to the outside via the discharge system 343 and the discharge blower 38 is essentially only water vapor (moisture). Therefore, in the above-described dew point regulator 13, even when the dehumidifying agent in the regenerator is in a standby state, carbon dioxide is not discharged to the outside of the furnace, thereby reducing the amount of carbon dioxide discharged.

[0047] The atmospheric furnace 10 of the present invention can reduce the moisture content in the atmospheric gas by adjusting the dew point temperature of the atmospheric gas using the above-mentioned dew point regulator 13, and as a result, can reduce carbon dioxide in the atmospheric gas through the water-gas shift reaction, which is a chemical reaction. In more detail, inside the furnace body 11 (furnace chamber), a water-gas shift reaction (hereinafter also referred to as "shift reaction") occurs in which carbon monoxide and water vapor in the atmospheric gas are the reactants, and carbon dioxide and hydrogen are purified from these as the products. Normally, the shift reaction inside the furnace body 11 (furnace chamber) is in an equilibrium state. The relational expression of the shift reaction in this equilibrium state is shown in Chemical Formula 1.

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

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

[0050] [ka]

[0051] That is, the atmosphere furnace 10 of the present invention can reduce the amount of carbon dioxide in the atmosphere gas by removing moisture (water vapor) from the atmosphere gas using the dew point regulator 13, thereby causing a reverse shift reaction inside the furnace body 11. In other words, the atmospheric furnace 10 of the present invention reduces the amount of carbon dioxide by chemical means utilizing the reverse shift reaction, rather than by physical means such as capturing carbon dioxide with a filter or adsorbent.

[0052] In the shift reaction, the reverse shift reaction is likely to occur in an atmosphere of about 650°C. Therefore, from the viewpoint of favorably causing the reverse shift reaction, the lower limit of the furnace temperature of the portion (furnace chamber) inside the furnace body 11 to which the atmospheric gas from which moisture has been removed using the dew point regulator 13 is returned is preferably 650°C or higher. The lower limit of the furnace temperature of this portion (furnace chamber) is more preferably 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 for analyzing the CO concentration and CO 2 concentration inside the furnace body 11 . The analyzer 14 is electrically connected to the controller 16 (see FIG. 1), and can input information relating to the analyzed CO concentration and CO 2 concentration to the controller 16. The analyzer 14 is not particularly limited in configuration, etc., as long as it is capable of analyzing the CO concentration and CO2 concentration in the furnace chamber. For example, the analyzer 14 may include a measuring instrument (not shown) that measures the CO concentration and CO2 concentration inside the furnace body 11. Specifically, the measuring instrument may include sensors such as a CO sensor and a CO2 sensor.

[0054] In the atmosphere furnace 10 of the present application, the carbon potential (hereinafter also abbreviated as "CP"), which indicates the carbon concentration (carbon equivalent), of the atmosphere inside the furnace body 11 is controlled so as to be suitable for heat treatment of the workpiece. In order to control this CP, it is necessary to obtain an actual measured value of CP inside the furnace body 11. The analyzer 14 has a function of analyzing the CO concentration and CO2 concentration during heat treatment in the calculation means provided in the controller 16 to obtain the actual measured value of CP. Specifically, the analyzer 14 can analyze the CO concentration and CO2 concentration inside the furnace body 11 constantly or at regular intervals. Information on the CO concentration and CO2 concentration analyzed by the analyzer 14 is input to the controller 16 and used to calculate the actual measured value of CP.

[0055] In the batch and continuous atmospheric furnaces 10, the attachment position of the analyzer 14 to the furnace body 11 is not particularly limited as long as the CO concentration and CO 2 concentration inside the furnace body 11 can be measured. In the case of a continuous atmospheric furnace 10, from the viewpoint of CP control, the furnace can be configured so that an analyzer 14 is attached to each of two or more furnace chambers selected from a plurality of 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 annealing chamber, has a different optimal CP for processing. Therefore, from the perspective of CP control, it is preferable to install an analyzer 14 in each of two or more furnace chambers selected from the multiple furnace chambers to monitor and manage the CO concentration and CO2 concentration. Among the multiple furnace chambers, the heating chamber and the annealing chamber are particularly preferable as furnace chambers to install the analyzer 14 in.

[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 FIG. 1), and can input information relating to the measured dew point temperature of the atmospheric gas inside the furnace body 11 to the controller 16. The dew point meter 15 is not particularly limited in configuration as long as it can measure the dew point temperature of the atmospheric gas inside the furnace body 11, and any known dew point meter can be used.

[0057] The atmospheric furnace 10 of the present application can reduce the amount of carbon dioxide in the atmospheric gas by removing moisture (water vapor) from the atmospheric gas, which means that the CO2 concentration inside the furnace body 11 (furnace chamber) can be adjusted by changing the amount of moisture (dew point temperature) in the atmospheric gas, and CP can be controlled based on this adjustment of the CO2 concentration. Therefore, to control CP by adjusting the CO2 concentration, it is necessary to measure the dew point temperature. The dew point meter 15 has a function of measuring the dew point temperature and inputting it to the controller 16. The controller 16 can control the CP by adjusting the CO2 concentration based on the dew point temperature input from the dew point meter 15. Specifically, the dew point meter 15 can constantly or at regular intervals measure the dew point temperature inside the furnace body 11. Information on the dew point temperature 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 the batch and continuous atmospheric 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 dew point meter 15 is preferably attached to the furnace body 11 in each furnace chamber, such as the heating chamber, the soaking chamber, the annealing chamber, etc., from the viewpoint of controlling CP in multiple furnace chambers. In other words, in the case of a continuous atmosphere furnace 10, in order to control CP in multiple furnace chambers, such as the heating chamber, the soaking chamber, the annealing chamber, etc., it is preferable to attach a dew point meter 15 to each furnace chamber, such as the heating chamber, the annealing chamber, the annealing chamber, etc.

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

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

[0061] Specifically, the supply section of the purge device may include a purge gas supply system 19A connected to the furnace body 11, an opening / closing 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 an inert gas as a purge gas into 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 feeding an inert gas as a purge gas into the purge gas supply system 19A, and specific examples thereof include a tank or cylinder for storing the inert gas, a generator for generating the inert gas, or a filter for collecting nitrogen (N2) as an inert gas from the air.

[0062] Specifically, the discharge section of the purge device may include a release system 18 connected to the furnace body 11 and a release valve 18A connected to the release system 18 to open and close the release system 18 (see Figure 1). The release system 18 is for discharging gas inside the furnace chamber to the outside of the furnace. Any type of release valve 18A can be used as long as it can open and close the release system 18, and 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 so that its opening and closing operation can be controlled by the controller 16 (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 above-mentioned purge device can also be used as a furnace pressure regulator for adjusting 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 section of the purge device can increase the furnace pressure by opening the purge gas supply system 19A with the opening / closing valve 19B and supplying inert gas from the purge gas supplier 19C to the furnace chamber via the purge gas supply system 19A. When the furnace pressure in the furnace body 11 is high, the exhaust section of the purge device can lower the furnace pressure by opening the release system 18 with the release valve 18A and discharging the gas inside the furnace chamber from the release system 18 to the outside of the furnace. When the purge device is used as a furnace pressure regulator as described above, the furnace pressure in the furnace chamber can be adjusted without using atmospheric gas (endothermic converted gas), which makes it possible to reduce the amount of atmospheric gas (RX gas) used in heat treatment, and by reducing the amount of atmospheric gas (RX gas) used, it is possible to reduce carbon dioxide emissions.

[0064] (6) Controller The controller 16 is for controlling the atmosphere inside the furnace body 11 (furnace chamber) to be suitable for heat treatment, and is mainly for controlling the CP of the atmosphere. More specifically, the controller 16 is connected to the dew point regulator 13, the analyzer 14, and the dew point meter 15, and adjusts the dew point temperature of the atmospheric gas to lower it, thereby controlling the CO2 concentration in the furnace chamber. The controller 16 can control the CP of the atmosphere in the furnace chamber of the furnace body 11 based on the reduction in CO2 concentration.

[0065] The controller 16 is electrically connected to the analyzer 14, and can obtain information on the CO concentration and CO 2 concentration inside the furnace body 11 (furnace chamber) analyzed by the analyzer 14. The controller 16 is provided with a calculation means for calculating the actual measured value of CP of the atmosphere inside the furnace body 11 (furnace chamber) based on the CO concentration and CO 2 concentration obtained from the analyzer 15.

[0066] The controller 16 is electrically connected to the supply blower 33 and the return valve 36 of the dew point regulator 13 and is capable of operating the supply blower 33 and the return valve 36 . The controller 16 is equipped with a first CP control means that adjusts the CO2 concentration inside the furnace body 11 (furnace chamber) by operating the supply blower 33 and return valve 36 of the dew point regulator 13 so that the CP inside the furnace body 11 (furnace chamber) becomes a preset value according to the heat treatment, thereby controlling the CP.

[0067] The controller 16 is electrically connected to the air regulating valve 214 and the raw material regulating valve 215 of the gas generator 21 , and can operate the air regulating valve 214 and the raw material regulating valve 215 . The controller 16 may be provided with a second CP control means for controlling the CP by operating the air adjustment valve 214 and the 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 has a built-in electronic calculator (computer) including a processing unit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and a storage area unit such as an HDD, SSD, or ROM. The above-mentioned calculation means, first CP control means, and second CP control means are stored in the storage area of ​​the controller 16 as programs. Furthermore, the CP suitable for the heat treatment is stored in the storage area of ​​the controller 16 as a preset CP setting value. The controller 16 can adjust the CO2 concentration inside the furnace body 11 (furnace chamber) and control the CP by having the electronic computer execute the calculation means, the first CP control means and the second CP control means as programs stored in the memory area unit based on the CP setting value stored in the memory area unit.

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

[0070] The controller 16 is electrically connected to the first adjusting valve 22 of the gas supply system 12 and is capable of operating the first adjusting 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 may be provided with a furnace pressure gauge 17 for measuring the furnace pressure inside (furnace chamber), and the furnace pressure gauge 17 may be electrically connected to the controller 16 (see FIG. 1). The furnace pressure gauge 17 is not particularly limited in type, etc., as long as it is capable of measuring the furnace pressure, and a pressure sensor or the like may be used. Furthermore, the controller 16 can store a furnace pressure suitable for the heat treatment in the storage area as a preset pressure.

[0071] The furnace pressure control means compares the furnace pressure obtained from the furnace pressure gauge 17 with a preset set 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 set pressure, thereby adjusting the furnace pressure. For example, when 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, thereby increasing the furnace pressure. On the other hand, when 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, thereby decreasing the furnace pressure.

[0072] When adjusting the amount of atmospheric gas supplied to control the furnace pressure, the CO2 concentration and CP (PF) may fluctuate inside (furnace chamber) of the furnace body 11. Therefore, if furnace pressure control is to be performed without changing the CO2 concentration and CP (PF), the above-mentioned purge device can be used as a furnace pressure regulator, and adjustment of the amount of inert gas supplied can be used to control the furnace pressure. Furthermore, when the above-mentioned purge device is used as a furnace pressure regulator to control the furnace pressure, if the furnace pressure is abnormally higher than the set pressure, the exhaust part of the purge device can be used to exhaust the gas inside the furnace body 11 (furnace chamber) to the outside of the furnace, thereby lowering the furnace pressure. In particular, the atmosphere furnace of the present invention uses the dew point regulator 13, the first CP control means, etc. to adjust the CO2 concentration inside the furnace body 11 (furnace chamber) to a value necessary and sufficient to maintain a CP (PF) suitable for heat treatment. Therefore, in the atmosphere furnace of the present invention, the amount of CO2 contained in the gas inside the furnace body 11 (furnace chamber) is less than that of a normal atmosphere furnace, so even if the gas inside the furnace body 11 (furnace chamber) is exhausted to the outside of the furnace, it is possible to reduce the amount of carbon dioxide emissions.

[0073] (7) Calculation means The calculation means is a program for calculating the measured value of CP of the atmosphere inside the furnace body 11 (furnace chamber). The calculation means performs calculations to calculate the actual measured value of CP 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 by 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. In addition, in equation (2), K is an equilibrium constant, and based on the Boudouard 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 the above formula (2), Cs and K are constants. Therefore, the potential factor (hereinafter abbreviated as "PF") calculated by the following formula (3) can be treated as a value synonymous with CP. PF=(CO concentration) 2÷(CO2 concentration)...Equation (3)

[0076] Regarding CP control, from equation (2) or equation (3), CP(PF) can be changed according to the CO2 concentration. Therefore, in the CP control, the CP (PF) of the atmosphere can be controlled by adjusting the CO2 concentration inside the furnace body 11 (furnace chamber) by the first CP control means and / or the second CP control means. Specifically, in the CP control, the first CP control means can increase the CP (PF) by reducing the CO2 concentration inside the furnace 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, or 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), and controls the CP (PF) by comparing the actual measured value of CP (PF) with the set value of CP (PF) and adjusting the CO2 concentration inside the furnace body 11 (furnace chamber) by operating the dew point regulator 13 so that the actual measured value of CP (PF) becomes the set value. In the first CP control means, the actual measured value of CP(PF) is calculated by the above-mentioned 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 set in advance depending on the heat treatment. In addition, the first CP control means can adjust the dew point temperature inside the furnace body 11 (furnace chamber) to reduce the CO2 concentration in order to control the CP (PF), and such a reduction in CO2 concentration contributes to a reduction in carbon dioxide emissions and further contributes to the regeneration of atmospheric gas.

[0078] The first CP control means has a first management means for operating the dew point regulator 13. This first management means is a program for managing the operation of the dew point regulator 13, and is included in the first CP control means. The first control means can adjust the amount of atmospheric gas taken into the dew point regulator 13 from the furnace body 11 (in other words, the amount of atmospheric gas discharged from the furnace body 11) by operating the supply blower 33 of the dew point regulator 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 regulator 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 regulator 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) 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 management means controls the operation of the dew point regulator 13, thereby taking in atmospheric gas containing a large amount of moisture from the inside of the furnace body 11 (furnace chamber) into the dew point regulator 13, and returning the atmospheric gas from which moisture has been removed by the dew point regulator 13 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 lowers the dew point temperature of the atmospheric gas, thereby causing the above-mentioned shift reaction (reverse shift reaction) to occur inside the furnace body 11 (furnace chamber), thereby reducing the CO2 concentration.

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

[0082] In the case of a batch-type atmospheric furnace, it is preferable to perform dew point adjustment at each process step, such as heating, soaking, and slow cooling.For this reason, it is also preferable to return the atmospheric gas from which moisture has been removed to the inside of the furnace body 11 (furnace chamber) at each process step. In a batch-type atmospheric furnace, it is more preferable to return the atmospheric gas from which moisture has been removed to the interior (furnace chamber) of the furnace body 11 after adjusting the temperature to the temperature range for each treatment such as heating, soaking, and slow cooling. In a batch-type atmosphere furnace, the furnace temperature during each process, such as heating, soaking, and slow cooling, increases over time in the case of heating treatment, decreases over time in the case of slow cooling treatment, and remains constant during the treatment in the case of soaking treatment. However, in all cases, there is a point at which the temperature reaches 650°C or higher, at which point the atmospheric gas from which moisture has been removed can be returned. Alternatively, in order to adjust the temperature of the ambient gas returned to the inside of the furnace body 11 (furnace chamber) to the temperature range of each process, a heater for heating the ambient gas, such as a heater, a cooler for cooling the ambient gas, such as a cooler, or a temperature regulator for heating and cooling the ambient gas, such as an air conditioner, can be connected between the dew point regulator 13 and the furnace body 11.

[0083] In the case of a continuous atmosphere furnace, since each process such as heating, soaking, and slow cooling is performed in multiple furnace chambers, it is preferable to select a furnace chamber where the furnace temperature is 650°C or higher and return the atmosphere gas from which moisture has been removed to that furnace chamber. In the case of a continuous atmospheric furnace, the number of furnace chambers to which the atmospheric gas from which moisture has been removed is returned may be one or two or more, provided that the furnace temperature is 650°C or higher. For example, in the case of a continuous atmospheric furnace having multiple furnace chambers connected to each other and atmospheric gas flowing back and forth between the multiple furnace chambers, the moisture (water vapor) in the atmospheric gas can be reduced throughout the interior of the furnace body 11 by returning the atmospheric gas to one furnace chamber. Alternatively, in the case of a continuous atmosphere furnace, since the CP differs between each furnace chamber, such as the heating chamber, soaking chamber, and annealing chamber, the CP of the atmosphere in each furnace chamber can be controlled using the first CP control means by returning atmospheric gas to each furnace chamber. In particular, since the CP differs greatly between the heating chamber and the annealing chamber, it is useful to return atmospheric gas to the heating chamber and the annealing chamber and control the CP of the atmosphere using the first CP control means. 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, and in that case, CP control can be performed at each furnace temperature (each processing temperature) while lowering the dew point in each furnace chamber. In a configuration in which multiple furnace chambers are connected to each other and atmospheric gas flows back and forth between the multiple furnace chambers, and atmospheric gas is returned to one furnace chamber, CP control can be performed using the first CP control means in each furnace chamber by knowing the amount of atmospheric gas entering (IN) and leaving (OUT) each furnace chamber by installing a measuring instrument in the furnace body 11, for example.

[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 favorably causing the shift reaction (reverse shift reaction), the upper limit is preferably 0°C or lower. 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 more, the moisture content can be significantly reduced, but the efficiency of the dew-point adjustment operation decreases and the load on the dew-point regulator 13 increases. Therefore, 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, and 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 uses hydrocarbon gas 13A gas as the raw material, and with a furnace temperature of 720°C, when the dew point temperature is 12°C, the CO2 concentration is 1.1% and the PF is 151, but when 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), and controls the CP (PF) by comparing the actual measured value of CP (PF) with the set value of CP (PF) and operating the gas generator 21 to adjust the CO2 concentration in the atmospheric gas so that the actual measured value of CP (PF) becomes the set value. In the second CP control means, the actual measured value of CP(PF) is calculated by the above-mentioned 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 set in advance depending on the heat treatment. In addition, the second CP control means can suppress the generation of excess CO2 by adjusting the CO concentration and CO2 concentration in the atmospheric gas supplied to the inside (furnace chamber) of the furnace body 11 to optimal values ​​so that the CP (PF) of the atmosphere inside (furnace chamber) of the furnace body 11 becomes a value suitable for heat treatment.Such adjustment of the 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 has a second management means for operating the gas supply system 12. This second management means is a program for managing 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 supply amount of the atmospheric gas (RX gas) supplied to the furnace body 11 by operating the first adjustment valve 22 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 the raw material adjustment valve 215 electrically connected to the controller 16. The second control means can reduce or increase the CO2 concentration in the atmospheric gas (RX gas) obtained in the transformer 211 by adjusting the amount of air and / or hydrocarbon gas supplied to the transformer 211.

[0087] The controller 16 is electrically connected to the analyzer 14, and can obtain information on the CO concentration and CO 2 concentration inside the furnace body 11 (furnace chamber) 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 information obtained from the analyzer 14.

[0088] Specifically, the second control means controls the operation of the gas generator 21 to reduce or increase the CO2 concentration in the atmospheric gas, thereby varying the CO2 concentration inside the furnace body 11 (furnace chamber). Moreover, the second control means adjusts the amount of atmospheric gas supplied to the furnace body 11 as necessary, thereby varying the CO2 concentration inside the furnace body 11 (furnace chamber). The second CP control means utilizes the fluctuation of the CO2 concentration by the second control means to adjust the CO2 concentration inside the furnace body 11 (furnace chamber), thereby being able to control the CP of the atmosphere.

[0089] Here, in the case of a batch-type atmospheric furnace, heat treatment including heating, soaking, and slow cooling is performed in one furnace chamber, so the second CP control means can be configured to control the furnace temperature and CP in coordination. That is, in the case of a batch-type atmospheric furnace, the second CP control means can have a third management means for operating the temperature regulator. This third management means is a program for managing the operation of the temperature regulator. The third control means operates the temperature regulator according to each of the heating, soaking, and slow cooling treatments, for example, by increasing the furnace temperature for the heating treatment, maintaining the furnace temperature for the soaking treatment, and decreasing the furnace temperature for the slow cooling treatment. Furthermore, the second CP control means can coordinately control the furnace temperature and CP by utilizing the second and third management means. For example, in the case of a heat treatment, CP can be increased as the furnace temperature increases, in the case of a soaking treatment, CP (PF) can be maintained along with the furnace temperature, and in the case of a slow cooling treatment, CP can be decreased as the furnace temperature decreases.

[0090] It should be noted that the second CP control means adjusts the CO2 concentration in the atmospheric gas (RX gas), but does not adjust the CP of the atmospheric gas (RX gas) itself, and in fact does not take into account the CP of the atmospheric gas (RX gas) itself. That is, the second CP control varies the CP of the atmosphere in one furnace chamber in a batch-type atmosphere furnace, and maintains the CP of the atmosphere in each furnace chamber in a continuous-type atmosphere furnace, but adjusts the CO2 concentration in the atmosphere gas (RX gas) to vary or maintain the CP of the atmosphere. Essentially, the second CP control performs CP control by adjusting the amount of CO2 supplied to the furnace body, and does not perform CP control by adjusting the CP of the atmosphere gas (RX gas). Furthermore, the second CP control involves adjusting the amount of CO2 supplied to the furnace body, and this adjustment optimizes the amount of CO2 in the atmospheric gas (RX gas) and reduces the amount of CO2 emitted as surplus, etc., thereby reducing carbon dioxide (CO2) emissions.

[0091] [2] Atmosphere control method 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, comprising: a first control step of controlling the operation of the dew point regulator 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, in order to make the atmosphere in the furnace chamber suitable for the heat treatment; The first management step includes: taking in the atmospheric gas from the furnace chamber; lowering the dew point temperature of the atmospheric gas; and a step of returning the atmospheric gas whose dew point temperature has been lowered to the furnace chamber, the temperature of which is 650°C or higher, to reduce the CO2 concentration in the furnace chamber.

[0092] Further, an 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, comprising: a first management step of managing the operation of the dew point regulator and a second management step of managing the operation of the gas supply system 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, 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 atmospheric gas from the furnace chamber, a step of lowering the dew point temperature of the atmospheric gas, and a step of returning the atmospheric gas whose dew point temperature has been lowered to the furnace chamber, the temperature of which is 650°C or higher, 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 for controlling the atmosphere inside the furnace body 11 (furnace chamber) in the above-mentioned atmosphere furnace 10 so that the CP inside the furnace body 11 (furnace chamber) becomes a preset value depending on the heat treatment. The atmospheric furnace 10 is equipped with a dew point regulator 13 and a controller 16 connected to the furnace body 11 to adjust the dew point temperature of the atmospheric gas (see Figure 1), and 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, in which the controller 16 controls the operation of the dew point regulator 13.

[0094] In addition, 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, in which the controller 16 controls the operation of the gas supply system 12 including the gas generator 21. Furthermore, the atmosphere control method can include a furnace pressure control step of controlling the furnace pressure after setting the CP (PF) inside the furnace body 11 (furnace chamber) of the atmosphere furnace 10 to a set value. Each step of the atmosphere control method will be described below.

[0095] (1) First management process The first control step is a step in which the controller 16 controls the operation of the dew point regulator 13 . The first control step can be executed by the controller 16 operating the dew point regulator 13 using the first control means (program) of the first CP control means (program) included in the controller 16.

[0096] FIG. 2 is a flowchart showing a specific example of the first management step. The first management process includes the following steps. A step of taking in atmospheric gas (S11). A step of lowering the dew point temperature (S12). A step of returning the atmospheric gas (S13). A step (S14) of determining whether the dew point temperature is 0°C or lower. A step (S15) of determining whether CP is a set value.

[0097] In step (S11), the controller 16 operates the supply blower 33 of the dew point regulator 13 to take in the atmospheric gas from the inside of the furnace body 11 (furnace chamber) into the dew point regulator 13 via the outflow pipe 31A of the gas circulation system. In this step (S11), the atmospheric gas taken into the dew point regulator 13 is cooled by the cooler 32 and then pressure-fed into the regenerator 34. In step (S12), the dew point temperature of the atmospheric gas taken into dew point regulator 13 is lowered. Specifically, the atmospheric gas pressurized into regenerator 34 passes through the inside of the regenerator in an adsorption state (first regeneration tower 341 in the state shown in FIG. 1), and during this passage, moisture (water vapor) contained in the gas is adsorbed by the dehumidifying agent and removed, thereby lowering the dew point temperature. In addition, the atmospheric gas whose dew point temperature has been lowered is temporarily stored in surge tank 35.

[0098] In step (S13), the controller 16 operates the return valve 36 of the dew point regulator 13 to return the atmospheric gas from the dew point regulator 13 to the inside (furnace chamber) of the furnace body 11 via the return pipe 31B of the gas circulation system. The atmospheric gas returned from the dew point regulator 13 has a lowered dew point temperature and a reduced moisture content, so the dew point temperature of the atmospheric gas inside the furnace body 11 (furnace chamber) drops. 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 at a temperature of 650°C or higher. This is because the reverse shift reaction occurs favorably in an atmosphere at a temperature of 650°C or higher. In other words, in a furnace chamber with a temperature of 650°C or higher, the amount of moisture (water vapor) in the atmospheric gas decreases when atmospheric gas with a lowered dew point is returned, so a reverse shift reaction occurs in which carbon dioxide and hydrogen in the atmospheric gas are purified into carbon monoxide and water vapor, thereby maintaining chemical equilibrium in the atmosphere. As a result, the amount of carbon dioxide in the atmospheric gas decreases, which contributes to reducing carbon dioxide emissions.

[0099] In step (S14), it is determined whether the dew point temperature inside (furnace chamber) of the furnace body 11 is 0°C or lower based on measurement by the dew point meter 15. In step (S14), for the furnace chamber to which the atmospheric gas is returned from the dew point regulator 13, it is determined from the dew point temperature whether the atmosphere in the furnace chamber is suitable for causing the shift reaction (reverse shift reaction). The dew point temperature can be set to 0°C or lower from the viewpoint of causing the shift reaction (reverse shift reaction) to occur favorably. In step (S14), if 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) is continuously lowered by returning the atmospheric gas from the dew point regulator 13. In step (S14), if it is determined that the dew-point temperature is 0° C. or lower (S14; yes), step (S15) is executed.

[0100] In step (S15), based on the measured value of CP calculated from the CO concentration and CO2 concentration obtained from the analyzer 14, it is determined whether CP is at the set value. In the step (S15), if it is determined that CP is the set value (S15; yes), the first management step is ended. In step (S15), if it is determined that CP is not the set value (S15; no), steps (S11) to (S14) are repeatedly executed. In other words, the first management process sends atmospheric gas from the inside of the furnace body 11 (furnace chamber) to the dew point regulator 13, removes moisture from the atmospheric gas, and returns it to the inside of the furnace body 11 (furnace chamber), thereby continuously causing a shift reaction (reverse shift reaction) to occur inside the furnace body 11 (furnace chamber), and adjusting the CO2 concentration to set the CP to a set value.

[0101] In the first control step, the CO2 concentration can be reduced by the shift reaction (reverse shift reaction). Therefore, it is preferable to use the first control step to control CP mainly when increasing CP. Furthermore, during the heat treatment of the workpiece, the CO concentration decreases and the CO2 concentration increases as the treatment progresses, which tends to decrease the CP. Normally, in order to suppress the decrease in CP, atmospheric gas (RX gas) is continuously supplied to the inside of the furnace body 11 (furnace chamber) during treatment. In contrast to this, the present invention performs so-called "regeneration treatment of atmospheric gas (RX gas)" in which moisture in the atmospheric gas is removed using the dew point regulator 13, causing a shift reaction (reverse shift reaction) inside the furnace body 11 (furnace chamber), increasing the CO concentration and decreasing the CO2 concentration. Therefore, it is possible to reduce the amount of atmospheric gas (RX gas) used, and also reduce the amount of carbon dioxide in the atmospheric gas (RX gas), thereby reducing CO2 emissions.

[0102] (2)Second control process The second control step is a step in which the controller 16 controls the operation of the gas supply system 12 . The second management process can be carried out by 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] FIG. 3 is a flowchart showing a specific example of the second management step. The second management process includes the following steps. A step of supplying an atmospheric gas (S21). A step of calculating and analyzing CP (S22). A step (S23) of determining whether CP is a set value. A step of reducing or increasing the CO2 concentration in the gas (S24).

[0104] In step (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 operates the first adjustment valve 22 to supply the atmospheric gas (RX gas) to the inside of the furnace body 11 (furnace chamber). In step (S22), the analyzer 14 measures the CO concentration and CO2 concentration inside the furnace body 11 (furnace chamber), and CP is calculated based on the measurements and analyzed as an actual measured value of CP.

[0105] In step (S23), it is determined whether CP is at a set value based on the analysis of the actual measured value of CP in step (S22). In the step (S23), if it is determined that CP is the set value (S23; yes), the second management step is ended. In step (S23), if it is determined that CP is not the set value (S23; no), step (S24) is executed. In the step (S24), the CO2 concentration in the atmospheric gas (RX gas) generated by the transformer 211 is reduced or increased by operating the air adjusting valve 214 and the raw material adjusting valve 215. After step (S24), steps (S22) and (S23) are repeated, and CP is set to the set value.

[0106] In other words, the second management process operates the gas supply system 12, including the gas generator 21, and adjusts the CO concentration and CO2 concentration in the atmospheric gas (RX gas) supplied to the inside (furnace chamber) of the furnace body 11, thereby setting the CP to a set value. Usually, in the second control step, the amount of hydrocarbon gas supplied to the transformer 211 is kept constant, and the amount of air supplied is increased or decreased, thereby making it possible to suitably adjust the CO2 concentration in the atmospheric gas (RX gas). The second control step appropriately adjusts the CO2 concentration in the atmospheric gas (RX gas) and suppresses the generation of excess CO2, thereby contributing to a reduction in carbon dioxide emissions.

[0107] In the present invention, since the first management process essentially performs the regeneration process of the atmospheric gas (RX gas), the second management process assists the first management process, enabling appropriate adjustment of the CO2 concentration in the regenerated atmospheric gas (RX gas). For example, in the case of a batch-type atmospheric furnace, there may be a transient period in which the CO2 concentration in the furnace chamber changes from moment to moment. In such cases, it is necessary to finely adjust and control the CP of the atmosphere by increasing and / or decreasing the CO2 concentration, so it is preferable to control the CP using the second control step in addition to the first control step.

[0108] (3) Furnace pressure control process The above-mentioned atmosphere control method can include a furnace pressure control process in which, after setting CP (PF) to a set value when controlling CP using the first control process and the second control process, the furnace pressure of the atmosphere inside the furnace body 11 (furnace chamber) is controlled. The furnace pressure control process can be performed by comparing the furnace pressure (actual value) obtained from the furnace pressure gauge 17 with a set pressure that is preset 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 (actual value) becomes the set pressure. Specifically, the furnace pressure control step can be performed by the controller 16 operating the first adjustment valve 22 in step (S21) of the second management step described above, to adjust the supply amount of the atmospheric gas (RX gas). Furthermore, since the furnace pressure is likely to change during the slow cooling process included in the heat treatment, it is preferable to carry out the furnace pressure control step during the process related to the slow cooling. [Industrial Applicability]

[0109] The present invention is extremely useful from the viewpoint of carbon neutrality, since it can reduce the amount of carbon dioxide emitted in an atmospheric furnace that heat-treats workpieces. [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; opening / closing valve, 19C; purge gas supplier, 21; gas generator, 22; first adjusting valve, 211; transformer, 212; air supply system, 213; raw material supply system, 214; air adjusting valve, 215; raw material adjusting valve, 31A; gas circulation system supply pipe, 31B; gas circulation system return pipe, 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 recovery system, 345; pressure recovery valve.

Claims

1. CO and CO ２ An atmospheric furnace for heat-treating a workpiece in a furnace chamber filled with an atmospheric gas containing a furnace body including the furnace chamber; a gas supply system connected to the furnace body to supply 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; The CO concentration and CO ２ an analyzer for analyzing the concentration; a dew point meter that measures the dew point temperature of the atmospheric gas in the furnace chamber; The dew point regulator is connected to the analyzer and the dew point meter, and is adjusted to lower the dew point temperature of the atmospheric gas, thereby reducing the CO ２ and a controller that controls the atmosphere furnace so as to reduce the concentration.

2. The dew point regulator is a gas circulation system for circulating the atmospheric gas between the furnace body and the gas circulation system; a cooler that cools the atmospheric gas sent from the furnace chamber of the furnace body through the gas circulation system; 2. The atmospheric furnace according to claim 1, further comprising: a regenerator that adsorbs and removes moisture contained in the atmospheric gas cooled by the cooler to regenerate the atmospheric 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 includes a plurality of the regenerators, 3. The atmosphere furnace according to claim 2, wherein some of the plurality of regenerators are in an adsorption state, and the regenerators other than the regenerator in the adsorption state are in a standby state.

4. 2. The atmospheric furnace according to claim 1, wherein the atmospheric gas is an endothermic converted gas.

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

6. 2. The atmospheric furnace according to claim 1, wherein the controller adjusts the dew point temperature of the atmospheric gas to be lowered to 0° C. or lower.

7. The controller The CO concentration and CO ２ A calculation means for calculating a carbon potential of the furnace chamber based on the concentration; The dew point regulator is operated to adjust the carbon potential of the furnace chamber to a preset value according to the heat treatment. ２ 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 a hydrocarbon gas; the gas generator is connected to the controller; The controller The CO concentration and CO ２ A calculation means for calculating a carbon potential of the furnace chamber based on the concentration; The gas generator is operated to adjust the carbon potential to a preset value according to the heat treatment. ２ 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. 2. The atmospheric furnace according to claim 1, further comprising a purge device connected to the furnace body and supplying an inert gas to the furnace chamber to purge the interior of the furnace chamber.

10. 2. An atmosphere control method for controlling the atmosphere in a furnace chamber of an atmosphere furnace according to claim 1, comprising: The CO concentration and CO concentration obtained from the analyzer are used to make the atmosphere in the furnace chamber suitable for the heat treatment. ２ a first control step of controlling the operation of the dew point regulator so that the carbon potential of the furnace chamber calculated based on the concentration becomes a preset value corresponding to the heat treatment; The first management step includes: taking in the atmospheric gas from the furnace chamber; lowering the dew point temperature of the atmospheric gas; The atmospheric gas whose dew point temperature has been lowered is returned to the furnace chamber whose temperature is 650°C or higher, and the CO ２ and reducing the concentration of the fluorine-containing compound.

11. 2. An atmosphere control method for controlling the atmosphere in a furnace chamber of an atmosphere furnace according to claim 1, comprising: The CO concentration and CO concentration obtained from the analyzer are used to make the atmosphere in the furnace chamber suitable for the heat treatment. ２ a first control step of controlling an operation of the dew point regulator and a second control step of controlling an operation of the gas supply system so that a carbon potential in the furnace chamber calculated based on the concentration becomes a preset value corresponding to the heat treatment, The first management step includes a step of taking in the atmospheric gas from the furnace chamber, a step of lowering the dew point temperature of the atmospheric gas, and a step of returning the atmospheric gas whose dew point temperature has been lowered to the furnace chamber whose temperature is 650° C. or higher to reduce the CO 2 in the furnace chamber. ２ and reducing the concentration of the mixture, The second control step is to control the amount of CO in the atmospheric gas supplied to the furnace chamber. ２ An atmosphere control method comprising a step of reducing or increasing a concentration.

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

13. a furnace pressure gauge for measuring the furnace pressure of the atmosphere in the furnace chamber is provided in the furnace body; a furnace pressure control step of controlling a furnace pressure in the furnace chamber after setting the carbon potential in the furnace chamber to the set value, The furnace pressure control step includes:

12. The atmosphere control method according to claim 10, further comprising a step of comparing the furnace pressure obtained from the furnace pressure gauge with a set pressure that is preset depending on the heat treatment, and supplying the atmospheric gas to the furnace chamber or exhausting the atmospheric gas from the furnace chamber so that the furnace pressure becomes the set pressure.

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