JP7560710B2 - Heat Treatment System - Google Patents

Description

The present invention relates to a heat treatment system.

Patent Document 1 discloses a heat treatment system equipped with a heating furnace that heats an object to be heated. The heating furnace has a furnace body in which the object to be heated is placed. The furnace body is supplied with high-temperature heating gas generated by burning a mixture of fuel gas and oxidizer gas with a burner. The furnace body is also provided with an electric heater that heats the object to be heated. The heating gas heats the object to be heated inside the furnace body. The heating gas supplied to the furnace body is discharged through an exhaust passage. A heat exchanger is disposed in the exhaust passage. In the heat exchanger, heat is exchanged between the heating gas and the oxidizer gas. In the heat treatment system described in Patent Document 1, the heat of the heating gas released from the heating furnace is transferred to the oxidizer gas supplied to the burner to increase the temperature of the oxidizer gas, thereby improving the thermal efficiency of the heating furnace.

JP 2019-70496 A

The heating furnace described in Patent Document 1 includes components such as a burner, an electric heater, a heat exchanger, and an exhaust passage in addition to the furnace body. In addition, piping is also required to supply fuel gas and oxidant gas to the burner. Therefore, the heat treatment system described in Patent Document 1 tends to be large in size, and there is room for improvement in terms of installation space.

The object of the present invention is to provide a heat treatment system that can be made compact.

The heat treatment system for solving the above problem is a heat treatment system using a heating furnace that includes a furnace body in which an object to be heated is placed, a supply passage for supplying a heating gas that heats the object to be heated to the furnace body, an exhaust passage for exhausting the heating gas from the furnace body, a combustion device that generates the heating gas by burning fuel, an electric heater that heats the object to be heated, and a circulation fan that circulates the heating gas through the supply passage, the furnace body, and the exhaust passage in that order, and the combustion device is provided with a heat exchanger that exchanges heat between the heating gas discharged from the heating furnace and an oxidizing gas supplied to the combustion device.

In the above configuration, by providing a heat exchange section in the combustion device, the combustion device and heat exchanger are integrated without being provided separately. This makes it possible to save installation space compared to a configuration in which the combustion device and heat exchanger are provided separately in a heat treatment system. Therefore, the above configuration can contribute to the miniaturization of the heat treatment system.

In addition, in the above heat treatment system, the heating furnace includes a transport device that transports the heated object into the furnace body and transports the heated object out of the furnace body, a partition plate that includes a pair of opposing first side walls and a pair of second side walls that connect the pair of first side walls and surrounds the periphery, and a control panel attached to the partition plate, and an entrance portion for transferring the heated object from the outside to the transport device and an exit portion for discharging the heated object to the outside by the transport device are formed in a side wall of the partition plate other than the side wall to which the control panel is attached, and a confirmation window for checking the control amount of the combustion device is formed in the side wall of the partition plate to which the control panel is attached, and it is preferable that a plurality of the heating furnaces are provided in a connected configuration.

The control panel and inspection window are provided for the administrator of the heat treatment system to operate and check. Therefore, in the heating furnace, a certain amount of space is required on the side wall where the control panel and inspection window are located so that the administrator can pass through.

In the above configuration, no control panel is attached to the side wall on which the inlet and outlet of the heating furnace are formed, and no inspection window is formed either. Therefore, there is no need to provide space for an administrator on the side wall on which the inlet and outlet of the heating furnace are formed, and when multiple heating furnaces are connected, it is possible to position the side wall on which the outlet of one heating furnace is formed close to the side wall on which the inlet of the other heating furnace is formed. This shortens the distance between the heating furnaces, making it possible to miniaturize a heat treatment system constructed by connecting multiple heating furnaces.

In addition, in the above heat treatment system, when the heating furnaces include a first heating furnace and a second heating furnace, and the transport device in the first heating furnace is the first transport device and the transport device in the second heating furnace is the second transport device, it is desirable that the outlet of the first heating furnace and the inlet of the second heating furnace face each other, and that the heated object be directly transferred from the first transport device to the second transport device.

In the above configuration, the objects to be heated are transferred by a transport device provided in the heating furnace. This makes it possible to omit a separate transport device for transporting objects to be heated between heating furnaces. This makes it possible to further reduce the size of a heat treatment system configured by connecting multiple heating furnaces.

In addition, in the above heat treatment system, it is preferable that the combustion device includes a first combustion section that combusts fuel and oxidant gas, and a second combustion section that mixes and combusts primary combustion gas, oxidant gas, and fuel generated by the combustion of fuel and oxidant gas in the first combustion section.

When fuel and oxidant gas are supplied separately and diffusively burned, the temperature of the generated combustion gas becomes locally high on the flame surface. On the other hand, when oxidant gas and fuel are mixed with high-temperature primary combustion gas and burned, i.e., when high-temperature air combustion is performed, the occurrence of the phenomenon of locally high temperatures in the generated combustion gas can be suppressed.

In the above configuration, after generating high-temperature primary combustion gas in the first combustion section, the primary combustion gas is mixed with oxidant gas and fuel in the second combustion section to generate a high-temperature mixture and burn it. Therefore, the phenomenon in which the secondary combustion gas generated in the second combustion section of the combustion device becomes locally hot is suppressed, and temperature variation is reduced. Such secondary combustion gas constitutes a heating gas and circulates in the heating furnace. According to the above configuration, the temperature variation of the heating gas generated by mixing the secondary combustion gas with the gas in the heating furnace is suppressed, and the temperature of the heating gas is less likely to exceed the heat-resistant temperature of each component of the heating furnace, so the temperature of the heating gas can be increased. Therefore, it is possible to supply a higher-temperature heating gas to the furnace body, and the temperature rise rate of the heated object can be improved.

The heat treatment system has a combustion section to which the combustion device is attached, and the combustion section has a double-tube structure having an inner tube and an outer tube, and the outer tube is provided with an outlet section to which the supply passage is connected, an inlet section to which the exhaust passage is connected, and an attachment section to which the combustion device is attached, and the inner tube has a cylindrical communication end section connected to the outlet section, and a cylindrical open end section extending from the communication end section toward the attachment section, with one end on the attachment section side being open, and it is desirable that the combustion device attached to the attachment section is inserted into the open end section through the one end.

In the above configuration, the heated gas discharged from the furnace body to the exhaust passage flows into the combustion section through the inlet section. Inside the combustion section, the heated gas flows between the outer tube and the inner tube to one end of the open end, and flows into the inside of the inner tube through one end of the open end. The heated gas that flows into the inside of the inner tube passes through the communication end and flows out from the outlet section to the supply passage. In this way, a gas flow path is formed inside the combustion section by the inner tube and the outer tube, which allows the heated gas that flows in from the exhaust passage to flow out to the supply passage. Therefore, the heated gas generated in the combustion device flows to the supply passage without flowing back to the exhaust passage. In addition, the gas flow path also forms a flow that guides the heated gas discharged from the heating furnace, i.e., the heated gas that flows in from the exhaust passage, to the heat exchange section of the combustion device. Therefore, according to the above configuration, it is possible to ensure flame stability in the combustion device while smoothing the flow of the heated gas and improving thermal efficiency. In addition, because these gas flow paths are formed inside the combustion section, this contributes to further miniaturization of the heat treatment system compared to configurations in which the gas flow paths are formed outside the combustion section.

In addition, in the above heat treatment system, the heating furnace includes at least two heating furnaces, a temperature-raising furnace that raises the temperature of the object to be heated, and a soaking furnace that maintains the temperature of the object to be heated in the temperature-raising furnace, and it is desirable that the flow rate of the heating gas supplied to the furnace body in the temperature-raising furnace is faster than the flow rate of the heating gas supplied to the furnace body in the soaking furnace.

When heating an object placed inside the furnace body with heating gas, the faster the flow rate of the heating gas, the more heat is transferred to the object per unit time. Therefore, when raising the temperature of the object, it is desirable to increase the flow rate of the heating gas. On the other hand, if the flow rate of the heating gas is increased when maintaining the temperature of the heated object, the part of the object where the heating gas is blown will be heated only partially, making it difficult to maintain a uniform temperature throughout the object.

In the above configuration, the flow rate of the heated gas supplied to the furnace body in the temperature-raising furnace is faster than the flow rate of the heated gas supplied to the furnace body in the soaking furnace. Therefore, with the above configuration, it is possible to realize a heat treatment system that improves the efficiency of heating the object in the temperature-raising furnace while reducing temperature variation when maintaining the temperature of the object in the soaking furnace.

In addition, in the above heat treatment system, it is desirable that the electric heater is provided in at least one of the supply passage and the exhaust passage, and is provided at a location in the circulation path of the heated gas that is different from the combustion device.

The electric heater heats the heating gas circulating as the circulation fan is driven, and can heat the objects to be heated housed in the furnace body. By providing such an electric heater in a location separate from the combustion device, the objects to be heated can be heated using the electric heater even when the combustion device is not generating heating gas. As a result, it is possible to improve the degree of freedom in the heating mode of the objects to be heated, and to increase the flexibility in the heat treatment.

The above heat treatment system makes it possible to achieve miniaturization.

FIG. 1 is a perspective view showing a schematic configuration of a heat treatment system according to an embodiment. FIG. 2 is a perspective view showing a schematic configuration of a heating furnace. FIG. 4 is a perspective view of the heating furnace as viewed from another angle. FIG. 3 is a cross-sectional view showing the schematic configuration of the furnace body. FIG. FIG. 4 is a graph showing the relationship between the distance from an ignition position in a combustion device and the temperature of combustion gas. FIG. 2 is a perspective view showing a cross-sectional structure of a combustion section of a heating furnace. FIG. 4 is a perspective view of the heat treatment system as viewed from another angle. 3 is a graph showing the heat treatment mode of aluminum in a heat treatment system. 4 is a graph showing the heating mode of the furnace body and aluminum in the first heating furnace. FIG. 4 is a cross-sectional view showing a manner in which aluminum is transported between a first heating furnace and a second heating furnace. 6 is a graph showing the heating mode of the furnace body and aluminum in the second heating furnace. 6 is a graph showing the heating mode of the furnace body and aluminum in the third heating furnace. 13 is a graph showing the heating mode of the furnace body and aluminum in the fourth heating furnace. 11 is a graph showing a comparison of primary energy consumption in the heat treatment system of Comparative Example 1, Comparative Example 2, and the present embodiment. 11 is a graph showing a comparison of temperature rise times in the heat treatment systems of Comparative Example 1, Comparative Example 2, and the present embodiment; FIG. 13 is a perspective view showing an arrangement of heating furnaces in a modified example of the heat treatment system. FIG. 13 is a plan view of a modified example of the heat treatment system.

One embodiment of a heat treatment system will be described with reference to Figures 1 to 17. In this embodiment, a heat treatment system that performs heat treatment on aluminum A as an object to be heated will be described as an example.

As shown in FIG. 1, the heat treatment system 10 includes a plurality of heating furnaces 11 and one water tank 12. The plurality of heating furnaces 11 include a first heating furnace 11A and a second heating furnace 11B for solutionizing aluminum A, and a third heating furnace 11C and a fourth heating furnace 11D for age-hardening aluminum A. The water tank 12 is provided for cooling aluminum A. The heat treatment system 10 includes the first heating furnace 11A, the second heating furnace 11B, the water tank 12, the third heating furnace 11C, and the fourth heating furnace 11D arranged in a line. Therefore, the second heating furnace 11B is connected to the first heating furnace 11A, and the water tank 12 is connected to the second heating furnace 11B. In addition, the third heating furnace 11C is connected to the water tank 12, and the fourth heating furnace 11D is connected to the third heating furnace 11C. The first heating furnace 11A, the second heating furnace 11B, the third heating furnace 11C, and the fourth heating furnace 11D have the same configuration. Below, the configuration of the first heating furnace 11A will be described, and the second heating furnace 11B, the third heating furnace 11C, and the fourth heating furnace 11D will be given the same reference numerals as the first heating furnace 11A and detailed descriptions will be omitted.

The first heating furnace 11A has a support base 15. The support base 15 has a bottom 16 and a plurality of legs 17 fixed to the bottom 16. A partition plate 18 is fixed to the bottom 16. The partition plate 18 has a pair of first side walls 18A that face each other in the arrangement direction of the plurality of heating furnaces 11, and a pair of second side walls 18B that connect the pair of first side walls 18A. Hereinafter, the direction in which the first side walls 18A face each other is referred to as the first direction, and the direction perpendicular to the first direction on the horizontal plane is referred to as the second direction. The second side walls 18B face each other in the second direction. The partition plate 18 is formed in a rectangular frame shape in a plan view, and surrounds the periphery of the first heating furnace 11A. The first heating furnace 11A is divided into an inside and an outside by the partition plate 18.

As shown in FIG. 2, the first heating furnace 11A has a combustion section 20 inside a space surrounded by a partition plate 18. The combustion section 20 is fixed to the bottom 16 of the support base 15. The combustion section 20 consists of a cylindrical large diameter section 21 and a small diameter section 22 that is provided above the large diameter section 21 and has a smaller diameter than the large diameter section 21. A combustion chamber 20A is formed inside the large diameter section 21. The combustion section 20 is provided with its axial direction aligned vertically.

The first heating furnace 11A has a combustion device 30 attached to the small diameter portion 22. A fuel pipe 85 for supplying fuel and an air pipe 90 for supplying air containing oxygen as an oxidizing gas are connected to the combustion device 30. The combustion device 30 burns the fuel to generate a heating gas for heating the aluminum A.

The air pipe 90 is connected to a blower 93. Air is supplied to the inside of the air pipe 90 as the blower 93 is driven. The air pipe 90 is branched into three branch pipes 90A, and each branch pipe 90A is connected to the combustion device 30. The three branch pipes 90A are arranged in a line in the first direction and are shifted forward and backward in the second direction. In this way, the three branch pipes 90A are arranged in a shifted manner in the second direction so that they overlap when viewed from the first direction, thereby shortening the length of the branch pipes 90A in the first direction compared to when they are arranged in a line in the first direction without being shifted in the second direction. The branch pipes 90A are provided with instruments 91, such as a flowmeter that measures the flow rate of the supplied air and a pressure gauge that detects the pressure of the air. The branch pipes 90A are also provided with a flow control valve 92 for controlling the flow rate of the air.

The fuel pipe 85 supplies fuel (e.g., city gas, liquefied natural gas, etc.) stored in a fuel tank (not shown) to the combustion device 30. The fuel pipe 85 is connected to the combustion device 30. Although not shown, the fuel pipe 85 branches midway and is configured to be able to supply fuel to different positions in the combustion device 30. Also, although not shown, the fuel pipe 85 is provided with instruments such as a flow meter that measures the flow rate of the fuel being supplied and a pressure gauge that detects the pressure of the fuel.

The first heating furnace 11A has a supply passage 95 connected to the combustion section 20. The supply passage 95 is connected to a position slightly lower than the vertical center of the large diameter section 21. The other end of the supply passage 95 is connected to the furnace body 100. Heating gas for heating the aluminum A is supplied from the combustion section 20 to the furnace body 100 through the supply passage 95.

As shown in FIG. 3, the furnace body 100 is arranged alongside the combustion section 20 in the second direction. The furnace body 100 is formed in a rectangular box shape with a heating chamber 100A formed inside. The furnace body 100 is fixed onto the support stand 15 by a support frame (not shown). The supply passage 95 is connected to the upper part of the furnace body 100. The length of the furnace body 100 in the first direction is set to be approximately the same as the length of the first heating furnace 11A in the first direction, i.e., the distance between the pair of first side walls 18A, although it is slightly shorter than that.

As shown in FIG. 4, aluminum A is placed on a transport pallet P and placed inside the furnace body 100. The furnace body 100 has a first wall portion 101 and a second wall portion 102 that face each other in a first direction (left-right direction in FIG. 4). The first wall portion 101 has a first opening 101A for carrying aluminum A in. The second wall portion 102 has a second opening 102A for carrying aluminum A out. The furnace body 100 is provided with a first cover wall 103 that closes the first opening 101A and a second cover wall 104 that closes the second opening 102A. The first cover wall 103 and the second cover wall 104 are provided so that they can slide up and down by a lifting mechanism (not shown).

3 and 4, the furnace body 100 is equipped with a conveying device 110. The conveying device 110 has a plurality of rollers 111 arranged in a line in the first direction, pulleys 115 provided at both ends of each roller 111, and a plurality of belts 116 wound between the pulleys 115 of adjacent rollers 111. Each roller 111 is rotatably supported by the furnace body 100. The plurality of rollers 111 include a first external roller 112 arranged in front of the first cover wall 103, a second external roller 113 arranged in front of the second cover wall 104, and a plurality of (four in this embodiment) internal rollers 114 inserted inside the furnace body 100. A drive belt (not shown) is wound around the pulley 115 of the second external roller 113. The drive belt is driven to rotate by a motor (not shown). The second external roller 113 rotates as the drive belt is driven to rotate. When the second external roller 113 rotates, rotational power is transmitted via the belts 116, causing the first external roller 112 and the internal roller 114 to rotate. A transport pallet P is placed on each roller 111, and as the rollers 111 rotate, the transport pallet P moves and the aluminum A is transported. In this embodiment, the aluminum A is transported from the first wall 101 side toward the second wall 102 side.

As shown in FIG. 3, a discharge passage 120 is connected to the lower part of the furnace body 100. The discharge passage 120 extends in the second direction and is connected to the lower end of the combustion section 20. Therefore, the part of the combustion section 20 to which the discharge passage 120 is connected is located lower than the part of the combustion section 20 to which the supply passage 95 is connected. Heated gas is discharged from the furnace body 100 to the combustion section 20 through the discharge passage 120.

As shown in Figures 2 and 3, a circulation fan 125 and an electric heater 130 are provided in the supply passage 95. The circulation fan 125 is located at the top of the furnace body 100, and is disposed on the furnace body 100 side of the electric heater 130 in the supply passage 95. The circulation fan 125 is composed of, for example, a sirocco fan. When the circulation fan 125 is driven, the heated gas circulates in the order of the combustion section 20, the supply passage 95, the furnace body 100, and the exhaust passage 120. The circulation fan 125 is provided so that the drive amount can be appropriately changed according to the supplied power.

As shown in FIG. 2, the electric heater 130 is located to the side of the combustion section 20 and the furnace body 100, and is disposed in the supply passage 95 between the circulation fan 125 and the combustion section 20. The electric heater 130 is provided in a different location from the combustion device 30 in the circulation path of the heated gas in the first heating furnace 11A. That is, the combustion device 30 is provided in the combustion section 20, and the electric heater 130 is provided in the supply passage 95. The electric heater 130 has a heater wire 130A provided in the supply passage 95 and an electric current section 130B that applies current to the heater wire 130A, and is configured to be able to heat the gas flowing through the supply passage 95.

Next, the configuration of the combustion device 30 will be described.
As shown in FIG. 5 , the combustion device 30 includes a burner section 31 that performs two-stage combustion, ie, a first combustion and a second combustion, and a heat exchange section 75 .

The burner section 31 has a rod-shaped spark rod 32 inserted into the small diameter section 22. The spark rod 32 generates a spark discharge at its tip (lower end in FIG. 5). The base end (upper end in FIG. 5) of the spark rod 32 is fixed to the connecting section 40. The connecting section 40 is formed in a roughly cylindrical shape, and a plurality of connecting ports 40A are formed on its outer circumferential surface to which the above-mentioned fuel pipe 85 and air pipe 90 are connected. The end of the fuel pipe 85 branches into three, and these three branch ends are each connected to the connecting ports 40A.

A cylindrical first inner tube 46 is provided on the outer periphery of the spark rod 32 with a small gap between them. The base end of the first inner tube 46 is fixed to the connecting portion 40. The first inner tube 46 extends to a position close to the tip of the spark rod 32. The outer periphery of the spark rod 32 and the inner periphery of the first inner tube 46 form a first fuel passage 65 for supplying fuel to the periphery of the tip of the spark rod 32. The first fuel passage 65 is supplied with fuel from a branch end (not shown) of the fuel pipe 85 through a first connection passage 41 formed in the connecting portion 40.

A cylindrical second inner tube 47 is provided on the outer periphery of the first inner tube 46, separated from the first inner tube 46 by a predetermined gap. The base end of the second inner tube 47 is fixed to the connecting portion 40. The second inner tube 47 extends to a position close to the tip of the spark rod 32. The outer periphery of the first inner tube 46 and the inner periphery of the second inner tube 47 form a first air passage 66 for supplying air around the tip of the spark rod 32. Air is supplied to the first air passage 66 from the air piping 90 through the second connection passage 42 formed in the connecting portion 40.

As shown in FIG. 6, a spacer 48 is connected to the tip of the first inner tube 46. The spacer 48 maintains the distance between the first inner tube 46 and the spark rod 32. The spacer 48 also has three spokes 48A connected to the second inner tube 47, which maintain the distance between the first inner tube 46 and the second inner tube 47.

As shown in FIG. 5, a cylindrical third inner pipe 49 is provided on the outer periphery of the second inner pipe 47, with a predetermined gap between it and the second inner pipe 47. The base end of the third inner pipe 49 is fixed to the connecting portion 40. The third inner pipe 49 extends to the same position as the tip of the second inner pipe 47. The outer periphery of the second inner pipe 47 and the inner periphery of the third inner pipe 49 form a second fuel passage 67 for supplying fuel around the tip of the spark rod 32. Between the second inner pipe 47 and the third inner pipe 49, a swirl nozzle 50 is provided for swirling the fuel flowing through the second fuel passage 67. The second fuel passage 67 is supplied with fuel from the branch end 85A of the fuel pipe 85 through the third connection passage 43 formed in the connecting portion 40. A passage groove 49A is formed on the outer periphery of the tip of the third inner pipe 49.

A cylindrical fourth inner tube 51 is provided on the outer periphery of the third inner tube 49, separated from the third inner tube 49 by a predetermined gap. The base end of the fourth inner tube 51 is fixed to the connecting portion 40. The fourth inner tube 51 extends to the back of the small diameter portion 22 beyond the tip of the spark rod 32. The outer periphery of the third inner tube 49 and the inner periphery of the fourth inner tube 51 form a second air passage 68 for supplying air around the tip of the spark rod 32. Air is supplied to the second air passage 68 from the air pipe 90 through the fourth connection passage 44 formed in the connecting portion 40.

The burner section 31 is provided with a cylindrical nozzle section 55 fixed to the third inner tube 49 and the fourth inner tube 51. The thickness of the wall of the nozzle section 55 is thicker than the thickness of the wall of the first inner tube 46, the second inner tube 47, the third inner tube 49, and the fourth inner tube 51. The nozzle section 55 extends to the inner side beyond the tip of the spark rod 32 and reaches the inner area of the large diameter section 21. The nozzle section 55 has a base 56 arranged between the third inner tube 49 and the fourth inner tube 51. The base 56 is formed with a first communication passage 59 that communicates with the second air passage 68. The first communication passage 59 is connected to the passage groove 49A of the third inner tube 49, and the first communication passage 59 communicates with the second air passage 68 and the passage groove 49A. Therefore, the air supplied to the second air passage 68 is discharged from the passage groove 49A through the first communication passage 59 to the periphery of the tip of the spark rod 32. The passage groove 49A is configured to swirl the discharged air in the same direction as the fuel swirled by the swirl nozzle 50.

The nozzle portion 55 has an intermediate portion 57 that extends from the base portion 56 to the rear side of the small diameter portion 22. The intermediate portion 57 extends further rearward than the fourth inner tube 51. The nozzle portion 55 has an injection hole portion 58 that is located further rearward than the intermediate portion 57 and is disposed in the large diameter portion 21. The outer periphery of the injection hole portion 58 has a larger diameter than the intermediate portion 57. The inner peripheral surface of the injection hole portion 58 forms a tapered surface 58A that is larger in diameter as it approaches the rear of the large diameter portion 21.

The burner section 31 has a cylindrical fuel main pipe 63 arranged between the third inner pipe 49 and the fourth inner pipe 51. The base end of the fuel main pipe 63 is fixed to the connecting section 40, and the tip end is fixed to the base 56 of the nozzle section 55. The fuel main pipe 63 is arranged with a gap between the third inner pipe 49 and the fourth inner pipe 51. The fuel main pipe 63 forms part of a fuel main passage 69 for supplying fuel to the back side of the spark rod 32. Fuel is supplied to the fuel main passage 69 from the branch end 85B of the fuel pipe 85 through the fifth connection passage 45 formed in the connecting section 40.

In the nozzle portion 55, a second communication passage 60 is formed that communicates with the main fuel pipe 63 and constitutes a part of the main fuel passage 69. The second communication passage 60 is composed of a first straight passage 60A that extends linearly from the base portion 56 to the intermediate portion 57 toward the rear side, an annular passage 60B that is connected to the first straight passage 60A and is formed in an annular shape in the intermediate portion 57, and a plurality of second straight passages 60C that are connected to the annular passage 60B and extend linearly to the inner area of the large diameter portion 21. The second straight passages 60C open to the tapered surface 58A of the nozzle portion 58. In this way, the main fuel pipe 63 and the second communication passage 60 of the nozzle portion 55 constitute the main fuel passage 69.

A cylindrical head portion 64 is fixed to the outer circumferential surface of the injection hole portion 58 of the nozzle portion 55. The head portion 64 is disposed in the inner region of the large diameter portion 21 of the combustion section 20.
The burner section 31 is provided with a cylindrical outer tube 62 provided outside the fourth inner tube 51. The outer tube 62 is arranged with a predetermined gap between it and the fourth inner tube 51. The outer tube 62 has a flange portion 62A that protrudes outward, and the flange portion 62A is joined to a fixed flange 22A formed on the small diameter portion 22 in the combustion section 20. This fixes the combustion device 30 to the small diameter portion 22. An air pipe 90 is connected to the outer tube 62. The tip of the outer tube 62 is located on the outer periphery of the intermediate portion 57 in the nozzle section 55. The outer periphery surface of the fourth inner tube 51 and the inner periphery surface of the outer tube 62 form a part of the main air passage 70 for supplying air to the back side of the spark rod 32. A third communication passage 61 that communicates with the inner area of the outer tube 62 is formed in the nozzle section 55. The third communication passage 61 extends within the nozzle portion 55, spanning from the intermediate portion 57 to the injection hole portion 58, and opens to the tapered surface 58A. The opening of the third communication passage 61 is formed to face the central axis of the nozzle portion 55. A main air passage 70 is formed by the outer circumferential surface of the fourth inner tube 51, the inner circumferential surface of the outer tube 62, and the third communication passage 61 of the nozzle portion 55.

The outer tube 62 constitutes the heat exchange section 75 of the combustion device 30. The heat exchange section 75 has a first annular fixing plate 76 that connects the tip of the outer tube 62 and the middle section 57 of the nozzle section 55.

As shown in FIG. 6, the first fixing plate 76 has a number of holes formed therein, into which the tips of the heat exchange pipes 77 fit. The tips of the heat exchange pipes 77 open into the inner area of the large diameter portion 21.

As shown in FIG. 5, the heat exchange pipes 77 are arranged between the fourth inner pipe 51 and the outer pipe 62 with a gap between them. The heat exchange section 75 is provided with a plurality of baffles 78 that hold the heat exchange pipes 77. The baffles 78 function to make the air flow meander in the main air passage 70.

The base end of each heat exchange pipe 77 is fixed to a second fixed plate 79 having a circular ring shape. A junction 80 is provided between the second fixed plate 79 and the connecting part 40. The junction 80 is composed of a cylindrical peripheral wall 80A and a sealing wall 80B that connects the end of the peripheral wall 80A on the connecting part 40 side. The inner area of the junction 80 is connected to the base end of the heat exchange pipe 77. An exhaust port 81 is formed in the peripheral wall 80A of the junction 80 to exhaust the internal gas.

As shown in FIG. 2, a discharge blower 82 is connected to the exhaust port 81. The discharge blower 82 is configured, for example, by a sirocco fan. The discharge blower 82 is configured so that the amount of drive can be appropriately changed according to the power supplied.

As shown in FIG. 5, the combustion device 30 is provided with a rod-shaped photoelectric sensor 83. The photoelectric sensor 83 is fixed to the connecting portion 40, and is positioned so that its tip faces the combustion flame generated in the burner portion 31. The photoelectric sensor 83 detects the amount of light from the flame as an electrical signal.

Next, the combustion mode in the combustion device 30 will be described.
The combustion device 30 first generates a first combustion by the burner section 31. In the first combustion, fuel is supplied through the first fuel passage 65 and air is supplied through the first air passage 66 to generate a mixture of fuel and air around the tip of the spark rod 32. In this state, a spark discharge is generated in the spark rod 32 to burn the mixture and generate a pilot flame S. At the same time, fuel is supplied through the second fuel passage 67 and air is supplied through the second air passage 68 to supply fuel and air around the tip of the spark rod 32. At this time, the second fuel passage 67 swirls the fuel and the second air passage 68 swirls the air so that the fuel swirls in the same direction as the fuel. Therefore, the mixture of the fuel supplied from the second fuel passage 67 and the air supplied from the second air passage 68 is ignited by the pilot flame S and combusted, generating a swirling flame R in the inner area of the middle section 57 of the nozzle section 55. In this way, by generating the swirling flame R, the combustion continuity of the pilot flame S and the swirling flame R is improved. In addition, by generating the swirling flame R, a vortex can be generated in the primary combustion gas generated by this combustion. In this way, in the first combustion, the pilot flame S ignites and burns the fuel and the oxidizer gas to generate the primary combustion gas. The primary combustion gas flows to the nozzle hole portion 58 of the nozzle portion 55 while swirling. When the photoelectric sensor 83 detects that the pilot flame S has been generated, the combustion device 30 stops the spark discharge in the spark rod 32. In addition, the air supplied through the first air passage 66 and the second air passage 68 is the outside air around the combustion device 30, which has an oxygen gas concentration of about 20% and a temperature of about 300K, and is supplied and used as it is.

After that, the combustion device 30 generates secondary combustion by the burner section 31. That is, fuel is supplied from the nozzle hole section 58 of the nozzle section 55 through the fuel main passage 69, and air is supplied from the nozzle hole section 58 of the nozzle section 55 through the air main passage 70. At this time, the air is supplied toward the central axis of the nozzle section 55, i.e., the primary combustion gas. Therefore, the primary combustion gas generated by the combustion that generates the swirling flame R is mixed with the air to generate a high-temperature mixture with a low oxygen concentration. Then, fuel is mixed with this mixture. When such a high-temperature mixture is mixed with fuel, so-called high-temperature air combustion occurs, in which the mixture ignites and burns without an ignition source. In this embodiment, the oxygen concentration of the mixture generated by mixing the primary combustion gas and air in the inner area of the head section 64 is set to 13% or less in volume concentration and the temperature is set to 1200K or more, so that the fuel is oxidized by flameless combustion, which is high-temperature air combustion. In flameless combustion, combustion occurs without forming a visible flame surface. Compared to normal combustion, flameless combustion produces more heat and less nitrogen oxides.

In this embodiment, the secondary combustion gas generated by the flameless combustion is supplied as heated gas from the head section 64 into the combustion chamber 20A. The heated gas supplied to the combustion section 20 is mixed with the gas flowing in the combustion section 20 by driving the circulation fan 125, and flows into the furnace body 100 through the supply passage 95. The heated gas flowing through the supply passage 95 may also be heated by the electric heater 130. The heated gas supplied to the furnace body 100 is returned to the combustion section 20 through the exhaust passage 120. Then, it is supplied again from the combustion section 20 to the furnace body 100 through the supply passage 95. In this way, the heated gas circulates inside the first heating furnace 11A.

In addition, in the first heating furnace 11A, the heated gas returned to the combustion section 20 can also be discharged to the outside through the heat exchange section 75 of the combustion device 30. That is, by driving the discharge blower 82, the heated gas returned to the large diameter section 21 of the combustion section 20 flows into the heat exchange pipe 77 of the combustion device 30. When the heated gas flows through the heat exchange pipe 77, it transfers heat to the air in the main air passage 70 flowing on the outer periphery of the heat exchange pipe 77. This increases the temperature of the air supplied from the main air passage 70 to the nozzle section 55, making it easier to increase the temperature of the mixture when this air is mixed with the primary combustion gas to 1200K or more. In this way, in the heat exchange section 75 of the combustion device 30, heat exchange is performed between the heated gas discharged to the exhaust passage 120 and discharged through the combustion device 30, and the air supplied to the combustion device 30 to cause secondary combustion. As a result, the heat wasted from the first heating furnace 11A can be recovered and reused, which contributes to improving the thermal efficiency of the first heating furnace 11A. The heated gas that flows through the heat exchange pipe 77 to the junction 80 is discharged from the exhaust port 81 through the discharge blower 82 to the top of the first heating furnace 11A.

Incidentally, it is desirable for the temperature of the heating gas circulating within the first heating furnace 11A to be high in order to shorten the time it takes for the aluminum A to heat up. However, since the above-mentioned components constituting the first heating furnace 11A have a heat-resistant temperature, it is difficult to heat the heating gas to a temperature that exceeds this heat-resistant temperature. In this embodiment, since the heat-resistant temperature Tr (e.g., 600°C) of the circulation fan 125 is lower than the heat-resistant temperatures of the other components, the temperature of the heating gas is set so as not to exceed the heat-resistant temperature Tr of the circulation fan 125.

7, when fuel and outside air are diffusively burned, the temperature of the generated combustion gas becomes locally high on the flame surface. In such combustion, the heating gas in the combustion section 20 becomes locally high temperature, but the temperature of the heating gas drops rapidly as it moves away from the combustion device 30. Therefore, if the temperature of the heating gas is set not to exceed the heat-resistant temperature Tr at the first position D1 corresponding to the circulation fan 125, the temperature of the heating gas drops significantly (for example, 500 ° C) at the second position D2 corresponding to the heating chamber 100A, which is further downstream. On the other hand, in this embodiment, the heating gas is generated by the above-mentioned flameless combustion. Therefore, as shown by the solid line in FIG. 7, it is difficult for the combustion gas to become locally high temperature, and if the heat generation amount by the flameless combustion is the same as the heat generation amount by the combustion shown by the dashed line in FIG. 7, the heating gas will maintain a high temperature over a wide range. That is, in flameless combustion, even if the temperature of the heated gas is set so as not to exceed the heat-resistant temperature Tr at the first position D1 corresponding to the circulation fan 125, the temperature of the heated gas can be maintained at a relatively high temperature (e.g., 590°C) at the second position D2 corresponding to the heating chamber 100A. In this way, by performing flameless combustion in the combustion device 30, it is possible to raise the temperature of the heated gas to a temperature close to the heat-resistant temperature Tr, which promotes heat transfer to the aluminum A and increases the temperature rise rate.

In the combustion device 30 of this embodiment, the first combustion section that burns the fuel and the oxidizer gas is composed of the spark rod 32, the connecting section 40, the first inner tube 46, the second inner tube 47, the third inner tube 49, the fourth inner tube 51, and the nozzle section 55. The second combustion section that mixes and burns the primary combustion gas, the oxidizer gas, and the fuel is composed of the connecting section 40, the fourth inner tube 51, the nozzle section 55, the main fuel tube 63, and the outer tube 62. The heat exchange section 75 is composed of the outer tube 62, the heat exchange pipe 77, the first fixing plate 76, the baffle 78, the second fixing plate 79, and the junction section 80.

As shown in FIG. 8, the combustion section 20 to which the combustion device 30 is attached has a double-tube structure having an inner tube 23 and an outer tube 24. The outer tube 24 constitutes the large diameter section 21 and the small diameter section 22 described above. The small diameter section 22 corresponds to the attachment section to which the combustion device 30 is attached. The outer tube 24 has an outlet section 24A to which the supply passage 95 is connected, and an inlet section 24B to which the exhaust passage 120 is connected. As described above, since the exhaust passage 120 is connected below the supply passage 95, the inlet section 24B is located below the outlet section 24A.

The inner tube 23 has a cylindrical communicating end 23A connected to the outlet 24A, and a cylindrical open end 23B extending from the communicating end 23A toward the small diameter portion 22, i.e., upward, with one end (upper end in FIG. 8) on the small diameter portion 22 side being open. The open end 23B is formed in a shape with an expanded diameter on the small diameter portion 22 side. The open end 23B extends to the outer periphery of the head portion 64 of the combustion device 30. Therefore, the head portion 64 of the combustion device 30 attached to the small diameter portion 22 is inserted into the open end 23B through the one end.

8, in this type of combustion section 20, the heated gas discharged from the furnace body 100 to the exhaust passage 120 flows into the lower end of the large diameter section 21 through the inlet section 24B. The heated gas then flows upward between the outer tube 24 and the inner tube 23 to one end side of the open end 23B, and flows into the inside of the inner tube 23 by turning back downward at the upper end portion of the large diameter section 21. At this time, the heated gas flows into the inside of the inner tube 23 through one end of the open end 23B. The heated gas then flows downward inside the inner tube 23 and flows out to the supply passage 95 through the outlet section 24A.

By this gas flow in the combustion section 20, the heated gas (secondary combustion gas) generated in the inner region of the head section 64 of the combustion device 30 is guided to the inside of the inner tube 23. Then, this secondary combustion gas is mixed with the gas circulating in the first heating furnace 11A to form a heated gas, which is supplied to the supply passage 95. In this way, by forming a flow path for the heated gas inside the combustion section 20 by the inner tube 23 and the outer tube 24, a flow is formed that flows the heated gas generated by the combustion device 30 to the supply passage 95. Therefore, the heated gas generated by the combustion device 30 flows to the supply passage 95 side without flowing back to the exhaust passage 120 side. In addition, in the combustion section 20, a gas flow path is formed so that the gas flows from the lower end to the upper end of the large diameter section 21, forming a flow that guides the heated gas discharged from the first heating furnace 11A to the heat exchange section 75 of the combustion device 30.

As shown in FIG. 9, the first heating furnace 11A is provided with a control panel 88. The control panel 88 is attached to the inner surface of the second side wall 18B of the partition plate 18. More specifically, the control panel 88 is attached to the second side wall 18B of the pair of second side walls 18B that is closer to the gauge 91 and flow control valve 92 of the air pipe 90 and the gauge of the fuel pipe 85. In the second side wall 18B, an opening is provided at a position corresponding to the part where the control panel 88 is attached, allowing the manager to operate, monitor, and inspect the control panel 88 from the outside. The control panel 88 executes various controls in the first heating furnace 11A according to the control parameters set by the manager. The various controls include, for example, combustion control in the combustion device 30, opening and closing control of the furnace body 100, drive control of the conveying device 110, drive control of the circulation fan 125, drive control of the electric heater 130, and drive control of the discharge blower 82.

The second side wall 18B to which the control panel 88 is attached has a confirmation window 181B formed as an opening. The confirmation window 181B is formed at a position corresponding to the gauge 91 and flow control valve 92 of the air pipe 90, and the gauge of the fuel pipe 85. In this embodiment, each gauge and flow control valve 92 are positioned close to the second side wall 18B so that the manager can operate them by inserting his or her hand into the confirmation window 181B. The manager operates, monitors, and inspects each gauge and flow control valve 92 through the confirmation window 181B. In other words, the combustion device 30 is operated, monitored, and inspected through these operations.

As shown in FIG. 1, an inlet portion 181A is formed in one of the pair of first side walls 18A. The inlet portion 181A is provided at a position corresponding to the first cover wall 103 of the furnace body 100. Aluminum A can be transferred from outside the first heating furnace 11A to the transport device 110 through the inlet portion 181A.

As shown in FIG. 9, an outlet portion 182A is formed in the other of the pair of first side walls 18A. The outlet portion 182A is provided at a position corresponding to the second cover wall 104 of the furnace body 100. The conveying device 110 can discharge aluminum A to the outside through the outlet portion 182A.

In the heat treatment system 10, aluminum A is treated as follows using a first heating furnace 11A, a second heating furnace 11B, a water tank 12, a third heating furnace 11C, and a fourth heating furnace 11D.
As shown in FIG. 10, first, the aluminum A is heated to a temperature T1 for solution treatment by the first heating furnace 11A. The temperature T1 is, for example, 480°C to 530°C, and is set to 500°C in this embodiment. After the aluminum A is heated to the temperature T1, it is then moved to the second heating furnace 11B and the temperature of the aluminum A is maintained at the temperature T1. After maintaining the temperature for a predetermined time, the aluminum A is moved to the water tank 12 and cooled and quenched. In this embodiment, the temperature of the aluminum A is cooled to a temperature T3 (room temperature to 70°C). The water tank 12 has a known configuration, and is configured to allow the aluminum A to be moved into the water tank 12 by, for example, a robot hand or a conveyor. As an example, in this embodiment, the water tank 12 is equipped with a lifting device that can lift and lower the aluminum A discharged from the outlet 182A of the second heating furnace 11B together with the transport pallet P to be submerged in the water tank 12.

In the heat treatment system 10, the aluminum A is moved to the water tank 12 to cool, and then heated to temperature T2 in the third heating furnace 11C to age harden the aluminum A. Temperature T2 is, for example, 180°C to 240°C, and is set to 220°C in this embodiment. Once the aluminum A has been heated to temperature T2, it is then moved to the fourth heating furnace 11D and the temperature of the aluminum A is maintained at temperature T2. After maintaining this temperature for a predetermined period of time, the aluminum A is removed from the fourth heating furnace 11D and allowed to cool naturally. This completes the series of heat treatments for the aluminum A.

In this way, in the heat treatment system 10, the first heating furnace 11A and the third heating furnace 11C function as heating furnaces that heat the aluminum A. Also, in the heat treatment system 10, the second heating furnace 11B and the fourth heating furnace 11D function as soaking furnaces that maintain the temperature of the aluminum A heated in the heating furnaces.

Next, the temperature regulation control in each heating furnace 11 will be described.
As shown by the solid line in FIG. 11, in the first heating furnace 11A, fuel and air are first supplied to the combustion device 30, and primary and secondary combustion is performed in the burner section 31 to generate high-temperature heating gas, and the internal temperature of the furnace body 100 is raised to a set temperature. The set temperature of the first heating furnace 11A is set according to the above-mentioned temperature T1 at which aluminum A is dissolved. Then, after timing t1 when the internal temperature of the furnace body 100 reaches the set temperature, the combustion mode in the combustion device 30 is controlled so that the internal temperature of the furnace body 100 is maintained at the set temperature. That is, when the internal temperature of the furnace body 100 is raised by the combustion device 30, it is necessary to increase the amount of heat generated compared to when the internal temperature of the furnace body 100 is maintained. Therefore, the amount of fuel and air supplied to the combustion device 30 is greater before timing t1 than after timing t1. In addition, in the first heating furnace 11A, the drive amount of the circulation fan 125 is set so that the flow rate of the heating gas is high. The flow rate of the heating gas can be determined and set in advance by simulation or experiment so as to be a flow rate preferable for raising the temperature of the aluminum A. When the aluminum A is carried into the furnace body 100 of the first heating furnace 11A in this state, the temperature of the aluminum A rises due to exposure to the heating gas, as shown by the dashed line in Fig. 11, and reaches temperature T1. When the temperature of the aluminum A rises to temperature T1, the aluminum A is moved from the first heating furnace 11A to the second heating furnace 11B.

As shown in FIG. 12, aluminum A is transported from the furnace body 100 of the first heating furnace 11A to the furnace body 100 of the second heating furnace 11B as follows. The transport device 110 of the first heating furnace 11A is referred to as the first transport device 110A, and the transport device 110 of the second heating furnace 11B is referred to as the second transport device 110B. The outlet 182A of the first heating furnace 11A and the inlet 181A of the second heating furnace 11B face each other. The distance between the first side wall 18A of the first heating furnace 11A and the first side wall 18A of the second heating furnace 11B is set to a distance that allows the transport pallet P to be transferred directly from the first transport device 110A to the second transport device 110B.

When the temperature of the aluminum A in the first heating furnace 11A is raised to temperature T1, the control panel 88 of the first heating furnace 11A moves the second cover wall 104 of the furnace body 100 to open the second opening 102A. Then, the control panel 88 of the first heating furnace 11A drives the first conveying device 110A to convey the aluminum A from the inside of the furnace body 100 to the outside. The control panel 88 of the second heating furnace 11B is configured to be able to communicate with the control panel 88 of the first heating furnace 11A. Therefore, when the second opening 102A of the furnace body 100 of the first heating furnace 11A is opened, the control panel 88 of the second heating furnace 11B moves the first cover wall 103 to open the first opening 101A in the furnace body 100 of the second heating furnace 11B and drives the second conveying device 110B. As a result, as shown by the solid line in FIG. 12, the transport pallet P transported by the first transport device 110A is transferred to the second transport device 110B. Then, as shown by the two-dot chain line in FIG. 12, the transport pallet P is accommodated inside the furnace body 100 of the second heating furnace 11B by the second transport device 110B. When aluminum A is accommodated inside the furnace body 100 together with the transport pallet P, the first cover wall 103 is moved in the second heating furnace 11B to close the first opening 101A. In addition, after the transport pallet P is handed over to the second transport device 110B in the first heating furnace 11A, the second cover wall 104 is moved to close the second opening 102A. In this way, when aluminum A is moved between the first heating furnace 11A and the second heating furnace 11B, aluminum A is directly transferred from the first transport device 110A to the second transport device 110B.

As shown by the solid line in FIG. 13, in the second heating furnace 11B, before the aluminum A is carried in, fuel and air are first supplied to the combustion device 30, and primary and secondary combustion is performed in the burner section 31 to generate high-temperature heated gas, and the internal temperature of the furnace body 100 is raised to the set temperature. The set temperature of the second heating furnace 11B is the same as the set temperature of the first heating furnace 11A. Then, after timing t2 when the internal temperature of the furnace body 100 reaches the set temperature, the combustion mode in the combustion device 30 is controlled so that the internal temperature of the furnace body 100 is maintained at the set temperature. In other words, after timing t2 when the internal temperature of the furnace body 100 has risen to the set temperature, the amount of fuel and air supplied to the combustion device 30 is reduced compared to before timing t2.

As shown by the dashed line in FIG. 13, aluminum A is carried into the second heating furnace 11B from the first heating furnace 11A while the internal temperature of the furnace body 100 is maintained by the combustion device 30. The aluminum A carried into the second heating furnace 11B is in a state after it has been heated to temperature T1 by the first heating furnace 11A. Therefore, the second heating furnace 11B requires less heat to maintain the temperature of the aluminum A. In the second heating furnace 11B, the amount of fuel after timing t2 is set to be less than the amount of fuel set in the first heating furnace 11A after timing t1.

In addition, in the second heating furnace 11B, the drive amount of the circulation fan 125 is set so that the flow rate of the heating gas supplied to the furnace body 100 is slower than the flow rate of the heating gas supplied to the furnace body 100 in the first heating furnace 11A. The flow rate of the heating gas in the second heating furnace 11B can be determined in advance by simulation or experiment and set to a flow rate that is favorable for maintaining the temperature of the aluminum A uniformly throughout.

As shown by the solid line in FIG. 14, in the third heating furnace 11C, before the aluminum A cooled in the water tank 12 is carried in, fuel and air are first supplied to the combustion device 30, and primary and secondary combustion is performed in the burner section 31 to generate high-temperature heated gas, and the internal temperature of the furnace body 100 is raised to the set temperature. The set temperature of the third heating furnace 11C is set to the above-mentioned temperature T2 for age-hardening the aluminum A. In addition, in the third heating furnace 11C, the amount of fuel and air supplied to the combustion device 30 is suppressed during the temperature rise by the combustion device 30, and the electric heater 130 is operated. As a result, in the third heating furnace 11C, the temperature is raised by the combustion device 30 and the electric heater 130. In this way, by using the combustion device 30 and the electric heater 130 together as a heat source, the primary energy consumption required for raising the temperature of the furnace body 100 can be reduced. In the third heating furnace 11C, at time t3 when the internal temperature of the furnace body 100 reaches the set temperature, the combustion in the combustion device 30 is stopped and only the electric heater 130 is driven. As a result, from time t3 onwards, the internal temperature of the furnace body 100 is maintained at the set temperature by the electric heater 130.

As shown by the dashed line in FIG. 14, while heating is being performed by the electric heater 130, aluminum A is transported from the water tank 12 to the third heating furnace 11C. In the third heating furnace 11C, the driving amount of the circulation fan 125 is set so that the flow rate of the heated gas is high. In this embodiment, the driving amount of the circulation fan 125 is set so that the flow rate of the heated gas supplied to the furnace body 100 in the third heating furnace 11C is the same as the flow rate of the heated gas supplied to the furnace body 100 in the first heating furnace 11A. When aluminum A is transported into the furnace body 100 of the third heating furnace 11C in this state, the temperature of the aluminum A rises due to exposure to the heated gas and reaches temperature T2. When the temperature of the aluminum A rises to temperature T2, the aluminum A is moved from the third heating furnace 11C to the fourth heating furnace 11D. The temperature T2 for age-hardening the aluminum A is lower than the temperature T1 for solutionizing the aluminum A. Therefore, the thermal energy required to heat the aluminum A in the third heating furnace 11C is less than the thermal energy required to heat the aluminum A in the first heating furnace 11A. Therefore, in the third heating furnace 11C, the heat source is limited to the electric heater 130 after timing t3, thereby further reducing primary energy consumption while still ensuring the necessary thermal energy.

As shown by the solid line in FIG. 15, in the fourth heating furnace 11D, before the aluminum A is carried in, fuel and air are first supplied to the combustion device 30, and primary and secondary combustion is performed in the burner section 31 to generate high-temperature heated gas, and the internal temperature of the furnace body 100 is raised to the set temperature. The set temperature of the fourth heating furnace 11D is the same as that of the third heating furnace 11C. In addition, in the fourth heating furnace 11D, the amount of fuel and air supplied to the combustion device 30 is suppressed during the temperature rise by the combustion device 30, and the electric heater 130 is operated. As a result, in the fourth heating furnace 11D, the temperature is raised by the combustion device 30 and the electric heater 130. In this way, by using the combustion device 30 and the electric heater 130 together as a heat source, the primary energy consumption required for raising the temperature of the furnace body 100 can be reduced. In the fourth heating furnace 11D, at the timing t4 when the internal temperature of the furnace body 100 reaches the set temperature, the combustion in the combustion device 30 is stopped and only the electric heater 130 is driven. As a result, after the timing t4, the internal temperature of the furnace body 100 is maintained at the set temperature by the electric heater 130. As shown by the dashed line in FIG. 15, while heating is being performed by the electric heater 130, aluminum A is carried into the fourth heating furnace 11D from the third heating furnace 11C. The transport mode of aluminum A from the third heating furnace 11C to the fourth heating furnace 11D is the same as the transport mode of aluminum A from the first heating furnace 11A to the second heating furnace 11B described above. The aluminum A carried into the fourth heating furnace 11D is in a state after it has been heated to temperature T2 by the third heating furnace 11C. Therefore, in the fourth heating furnace 11D, the amount of heat required to maintain the temperature of aluminum A is small. In the fourth heating furnace 11D, the heat source is limited to the electric heater 130 after timing t4, thereby further reducing primary energy consumption while still ensuring the necessary thermal energy.

In addition, in the fourth heating furnace 11D, the drive amount of the circulation fan 125 is set so that the flow rate of the heated gas supplied to the furnace body 100 is slower than the flow rate of the heated gas supplied to the furnace body 100 in the third heating furnace 11C. In this embodiment, the drive amount of the circulation fan 125 is set so that the flow rate of the heated gas supplied to the furnace body 100 in the fourth heating furnace 11D is the same as the flow rate of the heated gas supplied to the furnace body 100 in the second heating furnace 11B.

The primary energy consumption in the heat treatment system 10 of this embodiment will be described with reference to FIG. 16. FIG. 16 shows a graph of the primary energy consumption when aluminum A is subjected to the above-mentioned heat treatment by transporting it in sequence from the first heating furnace 11A to the fourth heating furnace 11D after the temperature rise of the furnace body 100 in each heating furnace 11 is completed. That is, the graph shows the amount of primary energy consumed from when aluminum A is brought into each heating furnace 11 until it is taken out. The initial temperature of aluminum A brought into the first heating furnace 11A is 25°C.

Figure 16 shows Comparative Example 1, which is a comparative example of the above-mentioned heat treatment system 10, in which heat treatment is performed using only the combustion device 30 without using the electric heater 130 in all heating furnaces 11 from the first heating furnace 11A to the fourth heating furnace 11D. In Comparative Example 1, the flow rate of the heating gas is set to a low speed in all of the first heating furnace 11A to the fourth heating furnace 11D. In Figure 16, the total amount of primary energy consumption in the first heating furnace 11A to the fourth heating furnace 11D in Comparative Example 1 is shown as 100%. In Comparative Example 1, the ratio of the primary energy consumption of each heating furnace 11 to the total amount of primary energy consumption is also shown. That is, in Comparative Example 1, the ratio of the primary energy consumption in the first heating furnace 11A to the total amount of primary energy consumption is shown as 21% (= primary energy consumption in the first heating furnace 11A in Comparative Example 1 / total amount of primary energy consumption in Comparative Example 1 x 100).

On the other hand, as a comparative example for the above-mentioned heat treatment system 10, the first heating furnace 11A and the second heating furnace 11B use only the combustion device 30, and the third heating furnace 11C and the fourth heating furnace 11D use only the electric heater 130 to perform heat treatment. In addition, in Comparative Example 2, the flow rate of the heating gas in the temperature-raising furnaces of the first heating furnace 11A and the third heating furnace 11C is set to high speed, and the flow rate of the heating gas in the soaking furnaces of the second heating furnace 11B and the fourth heating furnace 11D is set to low speed. Figure 16 shows the ratio of the primary energy consumption of each heating furnace 11 in Comparative Example 2 to the total amount of primary energy consumption in Comparative Example 1. That is, in Comparative Example 2, the ratio of the primary energy consumption in the first heating furnace 11A is 13% (= the primary energy consumption in the first heating furnace 11A in Comparative Example 2 / the total amount of primary energy consumption in Comparative Example 1 × 100). Therefore, it can be seen that in Comparative Example 2, the primary energy consumption in the first heating furnace 11A can be reduced by 7% compared to Comparative Example 1. Similarly, in Comparative Example 2, the primary energy consumption in the second heating furnace 11B can be reduced by 14% compared to Comparative Example 1, and the primary energy consumption in the third heating furnace 11C can be reduced by 9%. Furthermore, in Comparative Example 2, the primary energy consumption in the fourth heating furnace 11D can be reduced by 22% compared to Comparative Example 1. Thus, in the second comparative example, the primary energy consumption in the entire heat treatment system can be reduced by a total of 53% compared to the first comparative example.

On the other hand, the heat treatment system 10 of this embodiment corresponds to the case where the temperature of the heating gas in the first heating furnace 11A is further increased to 590°C in the configuration of Comparative Example 2. In Comparative Examples 1 and 2, the temperature of the heating gas in the first heating furnace 11A is 510°C. In the configuration of this embodiment, the proportion of primary energy consumption in the first heating furnace 11A is 7% (= primary energy consumption in the first heating furnace 11A of this embodiment / total amount of primary energy consumption in Comparative Example 1 x 100). Therefore, in this embodiment, the primary energy consumption when raising the temperature in the first heating furnace 11A to the temperature T1 for solutionizing aluminum A can be reduced by 14% compared to Comparative Example 1 and by 6% compared to Comparative Example 2. Because the control modes of the second heating furnace 11B to the fourth heating furnace 11D are the same as those of Comparative Example 2, the primary energy consumption in the entire heat treatment system 10 of this embodiment is reduced compared to Comparative Example 2 by the difference (6%) in the primary energy consumption in the first heating furnace 11A, and is reduced by a total of 59% compared to Comparative Example 1.

Also, referring to FIG. 17, the heating time of aluminum A in the first heating furnace 11A and the third heating furnace 11C is compared in Comparative Example 1, Comparative Example 2, and the heat treatment system 10 of this embodiment. In Comparative Example 1, in both the first heating furnace 11A and the third heating furnace 11C, heat treatment is performed using only the combustion device 30, and the flow rate of the heating gas is set to a low speed. On the other hand, in Comparative Example 2, heat treatment is performed using only the combustion device 30 in the first heating furnace 11A, and heat treatment is performed using only the electric heater 130 in the third heating furnace 11C. In Comparative Example 2, the flow rate of the heating gas in the first heating furnace 11A and the third heating furnace 11C is set to a high speed. In Comparative Example 2, the heating time in the first heating furnace 11A is increased by 2% compared to Comparative Example 1, but the heating time in the third heating furnace 11C is decreased by 4%, and the total heating time in both the first heating furnace 11A and the third heating furnace 11C is decreased by 2%.

In contrast, in the heat treatment system 10 of this embodiment, in the configuration of Comparative Example 2, the temperature of the heating gas in the first heating furnace 11A is further increased to 590°C. That is, in the heat treatment system 10, the heat treatment is performed using only the combustion device 30 in the first heating furnace 11A, and the heat treatment is performed using only the electric heater 130 in the third heating furnace 11C. In addition, the flow rate of the heating gas in the first heating furnace 11A and the third heating furnace 11C is set to a high speed. Then, in the first heating furnace 11A, the temperature of the heating gas is increased to 590°C. As a result, in the heat treatment system 10, the temperature rise time in the first heating furnace 11A is reduced by 32% compared to Comparative Example 1, and when combined with the 4% reduction in the temperature rise time in the third heating furnace 11C, the temperature rise time can be reduced by a total of 36%.

As described above, in the present embodiment, in the heat treatment system 10, the primary energy consumption is significantly reduced, and the temperature rise time of the aluminum A is significantly shortened.
The operation and effects of this embodiment will be described.

(1) In this embodiment, the combustion device 30 is provided with a heat exchange section 75 that exchanges heat between the heated gas discharged to the exhaust passage 120 and the air supplied to the combustion device 30. In this way, by providing the heat exchange section 75 in the combustion device 30, the combustion device 30 and the heat exchanger are integrated without being provided separately. Therefore, it is possible to reduce the installation space compared to a configuration in which the combustion device 30 and the heat exchanger are provided separately in the heat treatment system 10. This can therefore contribute to the miniaturization of the heat treatment system 10.

(2) In this embodiment, the partition plate 18 of each heating furnace 11 has an entrance portion 181A for transferring aluminum A from the outside to the transport device 110 and an exit portion 182A for discharging aluminum A to the outside by the transport device 110 formed on the first side wall 18A. Then, in the partition plate 18 of each heating furnace 11, a control panel 88 is attached to the second side wall 18B, and a confirmation window 181B is formed in this second side wall 18B. The control panel 88 and the confirmation window 181B are provided for the administrator of the heat treatment system 10 to operate, monitor, and inspect. Therefore, in the heating furnace 11, a predetermined space is required on the second side wall 18B side where the control panel 88 and the confirmation window 181B are arranged so that the administrator can pass through. On the other hand, it is not necessary to provide the above-mentioned space on the first side wall 18A side where the entrance portion 181A and the exit portion 182A are formed. Therefore, when multiple heating furnaces 11 are connected, the side wall in which the outlet portion 182A of one heating furnace 11 is formed is arranged close to the side wall in which the inlet portion 181A of the other heating furnace 11 is formed. This shortens the distance between the heating furnaces 11, making it possible to reduce the size of the heat treatment system 10 formed by connecting multiple heating furnaces 11.

In addition, by shortening the distance between the heating furnaces 11, the travel distance for transporting the aluminum A is also shortened. This makes it possible to reduce the amount of heat dissipated during the movement of the aluminum A between the heating furnaces 11, thereby improving the thermal efficiency of the heat treatment system 10.

(3) In this embodiment, the outlet 182A of the first heating furnace 11A and the inlet 181A of the second heating furnace 11B are opposed to each other, and aluminum A is directly transferred from the first conveying device 110A to the second conveying device 110B. Also, the outlet 182A of the third heating furnace 11C and the inlet 181A of the fourth heating furnace 11D are opposed to each other, and aluminum A is directly transferred from the conveying device 110 of the third heating furnace 11C to the conveying device 110 of the fourth heating furnace 11D. In this way, if aluminum A is transferred by the conveying device 110 provided in the heating furnace 11, there is no need to provide a separate conveying device for conveying aluminum A between the heating furnaces 11. Therefore, in a heat treatment system 10 configured by connecting multiple heating furnaces 11, it is possible to eliminate the space required for providing a separate conveying device, thereby further reducing the size.

(4) In the combustion device 30, the primary combustion gas, air, and fuel generated by burning fuel and air are mixed to generate heated gas by flameless combustion. In flameless combustion, the phenomenon that the generated heated gas becomes locally hot is suppressed, and the temperature variation is reduced. Therefore, even if the temperature of the heated gas generated by mixing the secondary combustion gas generated by flameless combustion with the gas in the heating furnace 11 is set to 590 ° C. and the temperature is close to 600 ° C., which is the heat resistance temperature Tr of the circulation fan 125, the temperature variation of the heated gas is suppressed, so that it is difficult to exceed the heat resistance temperature Tr of the circulation fan 125. Therefore, it is possible to supply a higher temperature heated gas to the furnace body 100, which contributes to improving the temperature rise rate of aluminum A. As shown in FIG. 17, the temperature rise rate of aluminum A brought into the furnace body 100 can be improved, which contributes to reducing the primary energy consumption of the heat treatment system 10 as shown in FIG. 16.

(5) The combustion section 20 has a double-tube structure having an inner tube 23 and an outer tube 24, and a gas flow path is formed inside. This gas flow path allows the heated gas generated by the combustion device 30 to flow through the inner tube 23 to the supply passage 95, and allows the heated gas that has flowed into the combustion section 20 to flow between the outer tube 24 and the inner tube 23, and then flows from the open end 23B where the combustion device 30 is located to the inner tube 23 and flows out again to the supply passage 95. This gas flow path formed inside the combustion section 20 forms a flow that allows the heated gas generated by the combustion device 30 to flow through the inner tube 23 to the supply passage 95. Therefore, the heated gas generated by the combustion device 30 flows to the supply passage 95 without flowing back to the exhaust passage 120 side. In addition, in the combustion section 20, a gas flow path is formed so that the gas flows from the lower end to the upper end of the large diameter section 21, forming a flow that guides the heated gas discharged from the heating furnace 11 to the heat exchange section 75 of the combustion device 30. Therefore, it is possible to ensure flame stability by suppressing the inflow of gas into the head portion 64 of the combustion device 30 while smoothing the flow of the heated gas and improving thermal efficiency. In addition, because such a gas flow path is formed inside the combustion portion 20, it can contribute to further miniaturization of the heat treatment system 10 compared to a configuration in which the gas flow path is formed outside the combustion portion 20.

(6) In this embodiment, a first heating furnace 11A and a third heating furnace 11C are provided as heating furnaces for heating the aluminum A, and a second heating furnace 11B and a fourth heating furnace 11D are provided as soaking furnaces for maintaining the temperature of the aluminum A heated in the heating furnaces.

When heating aluminum A placed inside the furnace body 100 with heating gas, the faster the flow rate of the heating gas, the greater the amount of heat transferred to the aluminum A per unit time. Therefore, when heating the aluminum A, it is desirable to increase the flow rate of the heating gas. On the other hand, if the flow rate of the heating gas is increased when maintaining the temperature of the heated aluminum A, the part of the aluminum A on which the heating gas is blown will be heated partially, making it difficult to maintain a uniform temperature throughout the aluminum A.

In this embodiment, the flow rate of the heated gas supplied to the furnace body 100 in the first heating furnace 11A and the third heating furnace 11C is set to be faster than the flow rate of the heated gas supplied to the furnace body 100 in the second heating furnace 11B and the fourth heating furnace 11D. Therefore, a heat treatment system 10 can be realized that improves the efficiency of heating the aluminum A in the first heating furnace 11A and the third heating furnace 11C while reducing the temperature variation when maintaining the temperature of the aluminum A in the second heating furnace 11B and the fourth heating furnace 11D. As a result of being able to improve the efficiency of heating the aluminum A in this way, as shown in FIG. 16, it is possible to contribute to reducing the primary energy consumption in the first heating furnace 11A and the third heating furnace 11C.

(7) In this embodiment, the electric heater 130 is provided in the supply passage 95 . Therefore, the electric heater 130 is disposed at a location different from the combustion device 30 in the circulation path of the heated gas.
The electric heater 130 heats the heating gas circulating with the driving of the circulation fan 125, and heats the aluminum A contained in the furnace body 100. By providing such an electric heater 130 at a location different from the combustion device 30, the aluminum A can be heated using the electric heater 130 even when the heating gas is not generated by the combustion device 30. That is, in the third heating furnace 11C and the fourth heating furnace 11D, the electric heater 130 is driven even when the internal temperature of the furnace body 100 is increased, and after the internal temperature of the furnace body 100 is increased to the set temperature, the heating gas is heated only by the electric heater 130. In this way, the degree of freedom of the heating mode in each heating furnace 11 is improved, and the flexibility in the heating process can be increased. In addition, heating by the electric heater 130 does not require intake and exhaust as in the combustion device 30, so it is desirable from the viewpoint of energy saving, and can contribute to reducing the primary energy consumption in each heating furnace 11 as shown in FIG. 16.

In addition, by arranging the electric heater 130 at a different location from the combustion device 30 in the circulation path of the heated gas, the combustion device 30 can be driven quickly even when the electric heater 130 is at a high temperature. In other words, if the combustion device 30 and the electric heater 130 are arranged as one unit, there is a possibility that erroneous ignition will occur in the combustion device 30 if fuel is supplied to the combustion device 30 when the electric heater 130 is at a high temperature. In this embodiment, such erroneous ignition is suppressed, making it possible to quickly transition from a state in which the electric heater 130 is driven to a state in which the combustion device 30 is driven. Therefore, it is also possible to respond to demand response for electricity.

(8) In this embodiment, the circulation fan 125 is disposed at the top of the furnace body 100, and is provided in a position close to the inlet of the heating chamber 100A in the circulation path of the heating gas. The circulation fan 125 stirs and flows the heating gas, so that the heating gas with a uniform temperature can be supplied to the heating chamber 100A. Therefore, the temperature variation when the aluminum A is heated can be reduced.

The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.
In the above embodiment, the circulation fan 125 and the electric heater 130 are provided in the supply passage 95. In this case, the circulation fan 125 and the electric heater 130 are arranged so that the circulation fan 125 is located on the furnace body 100 side. These arrangements can be changed as appropriate. For example, the electric heater 130 may be provided between the circulation fan 125 and the furnace body 100 in the supply passage 95. It is also possible to arrange the circulation fan 125 and the electric heater 130 in the exhaust passage 120. In this case, the circulation fan 125 and the electric heater 130 may be arranged in the exhaust passage 120 from the furnace body 100 side, or the electric heater 130 and the circulation fan 125 may be arranged in the exhaust passage 120 from the furnace body 100 side. In addition, the circulation fan 125 may be arranged in the supply passage 95 and the electric heater 130 may be arranged in the exhaust passage 120, or the electric heater 130 may be arranged in the supply passage 95 and the circulation fan 125 may be arranged in the exhaust passage 120. In order to increase the temperature of the heated gas in the heating chamber 100A while keeping the temperature of the heated gas flowing through the circulation fan 125 below the heat-resistant temperature Tr, it is desirable to provide the circulation fan 125 in the exhaust passage 120 so that the circulation fan 125 is disposed as far away as possible from the combustion device 30. In addition, the number of electric heaters 130 and circulation fans 125 is not limited to one, and a plurality of electric heaters 130 and circulation fans 125 may be provided.

In the above embodiment, an electric heater 130 may also be provided in the furnace body 100, and a configuration may be adopted in which the object to be heated is directly heated by radiant heat from the electric heater 130.
In the above embodiment, an example was shown in which the combustion device 30 was used to heat the furnace body 100 in the first heating furnace 11A and the second heating furnace 11B, but both the electric heater 130 and the combustion device 30 may be used to heat the furnace body 100. In addition, in at least one of the first heating furnace 11A to the fourth heating furnace 11D, it is also possible to heat the furnace body 100 using only the electric heater 130. That is, the electric heater 130 can generate heating gas that heats the object to be heated by heating the air circulating in the heating furnace 11 in conjunction with the driving of the circulation fan 125. The temperature of the furnace body 100 can be raised by supplying such heating gas to the furnace body 100.

In addition, in the third heating furnace 11C and the fourth heating furnace 11D, an example was shown in which an electric heater 130 is used instead of a combustion device 30 when the temperature of the furnace body 100 is raised and then maintained at a constant temperature. Instead of this configuration, a combustion device 30 may be used to maintain the temperature of the furnace body 100. For example, when an electric heater 130 is used, it is conceivable that the maximum daily usable power set by the contract may be exceeded. If electricity is used in excess of this maximum power, a surcharge may be added to the electricity usage fee. Therefore, in such cases, it may be preferable to use a combustion device 30 instead of an electric heater 130 from the perspective of electricity usage fees.

- In the above embodiment, an example was shown in which the object to be heated is transported to the next heating furnace 11 when the temperature of the object to be heated rises to a predetermined temperature in the first heating furnace 11A and the third heating furnace 11C, but the object to be heated may also be transported to the next heating furnace 11 when a preset time has elapsed.

In the above embodiment, the electric heater 130 may be integrated into the combustion device 30 .
In the above embodiment, the change in the flow rate of the heating gas in the heating furnace 11 is realized by controlling the drive amount of the circulation fan 125. The method of controlling the flow rate of the heating gas is not limited to this. For example, a control valve capable of changing the flow rate cross-sectional area may be provided at the connection portion of the furnace body 100 with the supply passage 95, and the flow rate of the heating gas supplied to the furnace body 100 may be temporarily increased by reducing the flow rate cross-sectional area with the control valve.

- In the above embodiment, the flow rate of the heated gas supplied to the furnace body 100 in the first heating furnace 11A and the third heating furnace 11C is faster than the flow rate of the heated gas supplied to the furnace body 100 in the second heating furnace 11B and the fourth heating furnace 11D. Such a configuration can be modified as appropriate. For example, the flow rate of the heated gas in the solution treatment may be faster than the flow rate of the heated gas in the age hardening treatment. In other words, it is possible to make the flow rate of the heated gas in the first heating furnace 11A faster than the flow rate of the heated gas in both the second heating furnace 11B and the third heating furnace 11C, and to make the flow rate of the heated gas in the second heating furnace 11B faster than the flow rate of the heated gas in the fourth heating furnace 11D. In addition, the flow rate of the heating gas may be changed depending on the situation in one heating furnace 11, for example, by setting the flow rate of the heating gas to a low rate when the furnace body 100 in the first heating furnace 11A is heated, and setting the flow rate of the heating gas to a high rate when the object to be heated is heated. It is also possible to set the flow rate of the heating gas in all heating furnaces 11 to the same rate, and not change the flow rate of the heating gas between the heating furnaces 11.

- In the above embodiment, the combustion device 30 generates heated gas by generating flameless combustion, but flameless combustion does not necessarily have to be performed. For example, heated gas may be generated by high-temperature air combustion, which has a higher oxidant gas concentration than flameless combustion, or primary combustion gas generated by igniting and burning fuel and oxidant gas may be generated as heated gas.

In the above embodiment, the heating furnace 11 and the water tank 12 are arranged in series. However, the arrangement of the heating furnace 11 in the heat treatment system is not limited to this.
18, in the heat treatment system 200, the first heating furnace 11A and the second heating furnace 11B are arranged in series in the first direction, and the third heating furnace 11C and the fourth heating furnace 11D are arranged in series in the first direction, and are arranged in two rows spaced apart in the second direction. The water tank 12 is arranged between these rows on the side of the second heating furnace 11B and the third heating furnace 11C. The heat treatment system 200 is provided with a 21st conveying device 201 for conveying the object to be heated from the outlet 182A of the second heating furnace 11B to the water tank 12, and a 22nd conveying device 202 for conveying the object to be heated from the water tank 12 to the inlet 181A of the third heating furnace 11C.

As shown by the arrows in FIG. 19, in this configuration, the object to be heated brought in from the entrance 181A of the first heating furnace 11A passes from the first heating furnace 11A to the second heating furnace 11B and is transported to the 21st conveying device 201. The 21st conveying device 201 conveys the object to be heated transported from the second heating furnace 11B toward the water tank 12. Therefore, the conveying direction in the 21st conveying device 201 is rotated 90° with respect to the conveying direction in the first heating furnace 11A and the second heating furnace 11B. The object to be heated transported from the 21st conveying device 201 to the water tank 12 is transported to the 22nd conveying device 202. The 22nd conveying device 202 conveys the object to be heated transported from the water tank 12 to the entrance 181A of the third heating furnace 11C. Therefore, the transport direction from the 22nd transport device 202 to the third heating furnace 11C is rotated by 90° with respect to the transport direction from the water tank 12 to the 22nd transport device 202. The heated object carried in from the inlet 181A of the third heating furnace 11C is transported from the third heating furnace 11C to the fourth heating furnace 11D, and is carried out from the outlet 182A of the fourth heating furnace 11D. The transport direction in the third heating furnace 11C and the fourth heating furnace 11D is rotated by 180° with respect to the transport direction in the first heating furnace 11A and the second heating furnace 11B. In this way, in the heat treatment system 200, the heated object can be transported along a U-shaped path in a plan view and subjected to heat treatment. As shown in FIG. 18, even in such a configuration, it is preferable to arrange the control panel 88 and the confirmation window 181B on the second side wall 18B on the side that does not face the second side wall 18B of the other heating furnace 11.

- When transporting the objects to be heated between the heating furnaces 11, a configuration is adopted in which the objects are handed over directly from one transport device 110 to the other transport device 110, but such a configuration is not essential. For example, a separate transport device may be provided between the heating furnaces 11, and the objects to be heated may be transported between the heating furnaces 11 by the separate transport device.

- The configuration of the transport device 110 is not limited to that described above. For example, a known configuration such as a robot arm or a belt conveyor may be used. Also, the object to be heated may be transported to the heating furnace 11 by human power without providing the transport device 110 to the heating furnace 11.

- In the above embodiment, a control panel 88 is provided for each heating furnace 11, but this configuration can be changed. For example, instead of providing a control panel 88 for each heating furnace 11, a single control panel that controls all of the heating furnaces 11 may be provided separately. Even in this configuration, it is preferable that the control panel for overall control is provided on the second side wall 18B of the partition plate 18.

Although the control panel 88 is attached to the inner circumferential surface of the second side wall 18B, the control panel 88 may be attached to the outer circumferential surface of the second side wall 18B.
In the above embodiment, the control panel 88 and the confirmation window 181B may be provided in the first side wall 18A in which the inlet portion 181A and the outlet portion 182A are formed. Also, the inlet portion 181A and the outlet portion 182A may be provided in the second side wall 18B.

In the above embodiment, at least a portion of the partition plate 18 may be omitted. For example, the pair of first side walls 18A may be omitted. Also, in the partition plate 18, at least one of the first side wall 18A and the second side wall 18B may be formed in a curved plate shape rather than a flat plate shape.

- In the above embodiment, the temperature of the heating gas is increased to 590°C, but the temperature of the heating gas may be increased to 510°C as in Comparative Example 2. That is, the heat treatment system also includes one that performs heat treatment control as in Comparative Example 2. It goes without saying that the heat treatment system may also perform heat treatment control as in Comparative Example 1 using the above-mentioned heating furnace 11. Therefore, the heat treatment system 10 includes one that performs heat treatment control as in Comparative Example 1. That is, even if a heat treatment system that performs heat treatment control as in Comparative Examples 1 and 2 is adopted, it is possible to obtain the above action and effect (1) by adopting a configuration similar to that of this embodiment as the configuration of the heating furnace 11.

- In the above embodiment, the combustion section 20 has a double-tube structure, but the inner tube 23 may be omitted. Also, the combustion section 20 may be omitted, and the combustion device 30 may be provided in another location, such as the supply passage 95.

- In the above embodiment, the heat treatment system 10 that performs heat treatment including quenching has been described as an example, but the form of heat treatment can be changed as appropriate. For example, it is also possible to apply a configuration similar to that of the above embodiment to a heat treatment system that performs heat treatment without quenching. In such a case, the water tank 12 can be omitted. In addition, the number of heating furnaces 11 is not limited to four, and can be changed to any number greater than or equal to one.

- In the above embodiment, aluminum is used as an example of the object to be heated, but the object to be heated is not limited to this. For example, the heat treatment may be performed using metals other than aluminum, glass, resin, etc. as the object to be heated. Furthermore, as the heat treatment, in addition to solution treatment, annealing treatment, drying treatment, etc. can also be performed.

10... Heat treatment system 11... Heating furnace 11A... First heating furnace (heating furnace)
11B...Second heating furnace (soaking furnace)
11C: Third heating furnace (heating furnace)
11D...Fourth heating furnace (soaking furnace)
12: Water tank 15: Support base 16: Bottom 17: Legs 18: Partition plate 18A: First side wall 181A: Inlet portion 182A: Outlet portion 18B: Second side wall 181B: Inspection window 20: Combustion portion 20A: Combustion chamber 21: Large diameter portion 22: Small diameter portion (mounting portion)
Reference Signs List 22A: fixed flange 23: inner tube 23A: communicating end 23B: open end 24: outer tube 24A: outflow section 24B: inflow section 30: combustion device 31: burner section 32: spark rod 40: connection section 40A: connection port 41: first connecting passage 42: second connecting passage 43: third connecting passage 44: fourth connecting passage 45: fifth connecting passage 46: first inner tube 47: second inner tube 48: spacer 48A: spokes 49: third inner tube 49A: passage groove 50: swirl nozzle 51: fourth inner tube 55: nozzle section 56: base section 57: middle section 58: nozzle hole section 58A: tapered surface 59: first connecting passage 60: second connecting passage 60A: first straight passage 60B: annular passage 60C...Second straight path 61...Third communication passage 62...Outer pipe 62A...Flange portion 63...Main fuel pipe 64...Head portion 65...First fuel passage 66...First air passage 67...Second fuel passage 68...Second air passage 69...Main fuel passage 70...Main air passage 75...Heat exchange portion 76...First fixing plate 77...Heat exchange pipe 78...Baffle 79...Second fixing plate 80...Confluence portion 80A...Peripheral wall 80B...Sealing wall 81...Exhaust port 82...Discharge blower 83...Photoelectric sensor 85...Fuel pipe 85A, 85B...Branch end portion 88...Control panel 90...Air pipe 90A...Branch pipe 91...Instrument 92...Flow rate control valve 93...Blower 95...Supply passage 100...Furnace body 100A...Heating chamber REFERENCE SIGNS LIST 101...first wall portion 101A...first opening 102...second wall portion 102A...second opening 103...first cover wall 104...second cover wall 110...conveyor device 110A...first conveyor device 110B...second conveyor device 111...roller 112...first outer roller 113...second outer roller 114...internal roller 115...pulley 116...belt 120...discharge passage 125...circulation fan 130...electric heater 130A...heater wire 130B...electric current supply section 200...heat treatment system 201...21st conveyor device 202...22nd conveyor device A...aluminum (object to be heated)
P...Transport pallet S...Pilot flame R...Rotating flame R

Claims (7)

A furnace body in which an object to be heated is placed;
A supply passage for supplying a heating gas for heating the object to the furnace body;
a discharge passage for discharging the heating gas from the furnace body;
A combustion device that generates the heated gas by burning a fuel;
An electric heater for heating the object to be heated;
A heat treatment system using a heating furnace including a circulation fan that circulates the heating gas through the supply passage, the furnace body, and the exhaust passage in this order,
the combustion device is provided with a heat exchanger that exchanges heat between the heating gas discharged from the heating furnace and an oxidant gas supplied to the combustion device. The heating furnace is
A conveying device that conveys the object to be heated into the furnace body and conveys the object to be heated out of the furnace body;
a partition plate including a pair of first side walls opposed to each other and a pair of second side walls connecting the pair of first side walls to surround the periphery;
A control panel attached to the partition plate,
An inlet portion for transferring the object to be heated from the outside to the conveying device and an outlet portion for discharging the object to be heated to the outside by the conveying device are formed on a side wall of the partition plate other than the side wall to which the control panel is attached,
A confirmation window for confirming a control amount of the combustion device is formed in the side wall of the partition plate to which the control panel is attached,
The heat treatment system according to claim 1 , wherein a plurality of the heating furnaces are provided in a connected relationship. The heating furnace includes a first heating furnace and a second heating furnace,
When the conveying device in the first heating furnace is a first conveying device and the conveying device in the second heating furnace is a second conveying device,
The outlet of the first heating furnace and the inlet of the second heating furnace are opposed to each other,
The heat treatment system according to claim 2 , wherein the object to be heated is directly transferred from the first transfer device to the second transfer device. The combustion device includes:
a first combustion section that combusts fuel and an oxidant gas;
The heat treatment system according to any one of claims 1 to 3, further comprising: a second combustion section that mixes and burns a primary combustion gas, an oxidant gas, and a fuel generated by combustion of a fuel and an oxidant gas in the first combustion section. A combustion unit to which the combustion device is attached,
The combustion section has a double-tube structure having an inner tube and an outer tube,
the outer tube is provided with an outlet portion to which the supply passage is connected, an inlet portion to which the exhaust passage is connected, and a mounting portion to which the combustion device is attached,
the inner pipe has a communicating end portion connected to the outflow portion and formed in a cylindrical shape, and a cylindrical open end portion extending from the communicating end portion toward the attachment portion, the one end of the open end portion being open on the attachment portion side,
The heat treatment system according to any one of claims 1 to 4, wherein the combustion device attached to the mounting portion is inserted into the open end through the one end. The heating furnace includes at least two heating furnaces, a temperature-raising furnace for raising the temperature of the object to be heated and a soaking furnace for maintaining the temperature of the object to be heated in the temperature-raising furnace,
The heat treatment system according to any one of claims 1 to 5, wherein a flow rate of the heating gas supplied to the furnace body in the temperature-raising furnace is set to be faster than a flow rate of the heating gas supplied to the furnace body in the soaking furnace. The heat treatment system according to any one of claims 1 to 6, wherein the electric heater is provided in at least one of the supply passage and the exhaust passage, and is provided at a position in a circulation path of the heating gas different from the combustion device.