Heating furnace

Abstract

To provide a heating furnace which can reduce a risk of generating cracks in a workpiece and can contribute to the uniformity improvement of an in-furnace gas temperature distribution .SOLUTION: Provided is a heating furnace which comprises plural heat storage coolers which are capable of introducing a cooling gas into the furnace and can suck an in-furnace gas. Each of the plural heat storage coolers comprises: a gas nozzle which is connected to the inside of the furnace; a gas port which is connected to the outside of the furnace, can switch air supply to the heat storage cooler and air exhaust from the heat storage cooler and connected to a gas piping system; a gas passage which connects the gas nozzle to the gas port and has a space for filling a heat storage body; and the heat storage body which is filled into the space for filling the heat storage body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heating furnace, and more particularly to a baking furnace. [Background technology]

[0002] There are batch and continuous types of kilns for firing ceramic products such as roof tiles, sanitary ware, tableware, and honeycomb structures (e.g., filters and heat exchangers). In either type, the workpiece must be cooled after it has been heat-treated.

[0003] A common method for cooling the workpiece is to directly inject the air outside the furnace as a cooling gas into the furnace and exchange heat with the workpiece to cool it (e.g., Japanese Patent No. 2859987, Japanese Patent Laid-Open No. 4-124586). In addition to direct cooling, a method of cooling using an indirect cooler is also known for the purpose of improving heat recovery efficiency and controllability of the heat curve (e.g., Japanese Patent Publication No. 3-40317, Japanese Patent Laid-Open No. 2020-29988). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2859987 [Patent Document 2] Japanese Patent Application Publication No. 4-124586 [Patent Document 3] Special Publication No. 3-40317 [Patent Document 4] JP 2020-29988 A Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the specifications of the workpiece, there is an optimal heat curve for performing the desired heat treatment on the workpiece. Therefore, the operating conditions of the heating furnace are usually set so as to obtain such an optimal heat curve. Although direct cooling and indirect cooling as described above are known for cooling the workpiece, the following problems remain.

[0006] In the case of direct cooling, the amount of cooling gas required to obtain the desired heat curve is supplied into the furnace, but it is difficult to precisely control the temperature of the cooling gas supplied into the furnace. For this reason, a large discrepancy often occurs between the temperature of the cooling gas supplied into the furnace and the gas temperature inside the furnace. In particular, in direct cooling, the surface of the workpiece passing a position close to the cooling gas supply port is rapidly cooled, which is likely to cause cracks. In addition, in the case of direct cooling, particularly in continuous heating furnaces, fluctuating the amount of cooling gas is likely to cause fluctuations in the furnace pressure in the cooling zone, which may cause irregularities in the gas flow inside the furnace.

[0007] In addition, indirect cooling has a poorer cooling capacity than direct cooling, so there is a problem that it is difficult to control the heat curve in the furnace by itself. In addition, indirect cooling does not have the ability to stir the gas in the furnace, so the gas temperature in the furnace is likely to be distributed. In particular, in the case of a continuous heating furnace, the gas temperature in the furnace is likely to be distributed in the cross section perpendicular to the direction of travel of the work. For this reason, a difference in cooling speed is likely to occur between the workpiece close to the indirect cooler and the workpiece far from the indirect cooler. If an attempt is made to optimize the cooling speed of the workpiece far from the indirect cooler, the workpiece close to the indirect cooler will be cooled excessively, and there is a risk of cracks occurring. On the other hand, if an attempt is made to optimize the cooling speed of the workpiece close to the indirect cooler, the workpiece far from the indirect cooler will be prone to insufficient heat removal.

[0008] Thus, both conventional direct and indirect cooling methods have problems in terms of suppressing cracks in the workpiece during cooling and uniformity of the in-furnace gas temperature distribution (in a continuous heating furnace, this means uniformity of the in-furnace gas temperature distribution in a cross section perpendicular to the direction of travel of the workpiece). The present invention was created in consideration of the above circumstances, and an object of the present invention is to provide a heating furnace that can reduce the risk of cracks occurring in the workpiece during cooling and can contribute to improving the uniformity of the in-furnace gas temperature distribution during cooling in one embodiment. [Means for solving the problem]

[0009] The inventors have conducted extensive research to solve the above problems and have found that by using a regenerative cooler having a specific structure, it is possible to supply a cooling gas into the furnace that has a small temperature difference from the gas temperature inside the furnace during cooling. The present invention has been completed based on this knowledge and is exemplified below.

[0010] [1] The apparatus is provided with a plurality of regenerative coolers capable of introducing a cooling gas into the furnace and sucking the gas in the furnace, Each of the plurality of regenerative coolers includes a gas nozzle communicating with the inside of the furnace, a gas port communicating with the outside of the furnace and connected to a gas piping system capable of switching between supplying air to the regenerative cooler and exhausting air from the regenerative cooler, a gas passage communicating the gas nozzle with the gas port and having a space for filling the regenerative cooler, and a regenerative cooler filled in the space for filling the regenerative cooler. Heating furnace. [2] The heating furnace is a continuous heating furnace having an inlet, a heating zone, a cooling zone, and an outlet in this order, for heat-treating at least one workpiece while transporting it from the inlet to the outlet in the furnace, The cooling zone is provided with the plurality of heat storage coolers. [1] The heating furnace according to the present invention. [3] The heating furnace according to [1] or [2], wherein at least one of the plurality of heat storage coolers has at least one inlet / outlet for heat storage exchange. [4] At least one of the plurality of storage coolers is a gas passage including a first gas passage extending horizontally from the gas nozzle and a second gas passage communicating with the first gas passage a space for filling the heat storage body located below the first gas passage; a first inlet / outlet for replacing the heat storage medium provided above the second gas passage; a communication passage that communicates the first port with a second gas passage; The heating furnace according to [3], [5] The heating furnace according to [3] or [4], wherein at least one of the plurality of heat storage coolers has a second inlet / outlet for heat storage exchange that communicates with a lower portion of the space for filling the heat storage. [6] The heating furnace according to any one of [1] to [5], wherein the heat storage body is in the form of a ball, a honeycomb or a mesh. [7] At least one of the plurality of regenerative coolers has the gas nozzle on a first inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle on a second inner wall opposite the first inner wall. The heating furnace according to any one of [1] to [6]. [8] A heating furnace according to [7], which satisfies one or both of the following conditions (1) and (2). (1) At least one of the plurality of regenerative coolers has the gas nozzle above half the height of the first inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle below half the height of the second inner wall. (2) At least one of the plurality of regenerative coolers has the gas nozzle above half the height of the second inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle below half the height of the first inner wall. [9] The heating furnace according to [7] or [8], wherein the number of regenerative coolers having the gas nozzles on the first inner wall is equal to the number of regenerative coolers having the gas nozzles on the second inner wall.

[10] A heating furnace described in any one of [7] to [9], wherein at least one regenerative cooler having the gas nozzle on the first inner wall and at least one regenerative cooler having the gas nozzle on the second inner wall are configured so that the timing of introducing cooling gas into the furnace and the timing of sucking in the gas in the furnace are reversed.

[11] The heating furnace according to [2] or any one of [3] to

[10] dependent on [2], wherein the cooling zone is provided with one or more cooling gas supply ports capable of introducing a cooling gas into the furnace, on a side closer to the outlet than the regenerative cooler among the plurality of regenerative coolers that is closest to the outlet, and each of the one or more cooling gas supply ports is connected to the gas port of at least one of the plurality of regenerative coolers, and is configured so that exhaust from the at least one regenerative cooler can be introduced into the furnace from the cooling gas supply port as a cooling gas.

[12] A heating furnace as described in

[11] , wherein the cooling zone is provided with one or more outside-furnace air inlet ports communicating with the outside of the furnace, located closer to the outlet than the cooling gas supply port closest to the outlet among the one or more cooling gas supply ports.

[13] The heating furnace according to any one of [1] to

[12] , which is a firing furnace. Effect of the Invention

[0011] According to the continuous heating furnace of the present invention, it is possible to supply cooling gas that has been heated in advance by the heat storage effect of the regenerative cooler into the furnace. Therefore, it is possible to supply cooling gas with little deviation from the furnace gas temperature into the furnace, and the risk of cracks occurring in the workpiece due to rapid cooling of the workpiece can be reduced. By using a regenerative cooler, no special energy is required to heat the cooling gas, which contributes to energy saving. In addition, the cooling gas supplied into the furnace from the gas nozzle of the regenerative cooler has a velocity and therefore has the effect of stirring the gas in the furnace. Therefore, it also contributes to improving the uniformity of the gas temperature distribution in the furnace during cooling. [Brief description of the drawings]

[0012] [Figure 1]1 is a schematic side view showing an example of the structure of a heat storage cooler according to an embodiment of the present invention; [Diagram 2] 1 is a side schematic view showing an example of the overall configuration of a continuous heating furnace according to an embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is a schematic plan view showing an example of the configuration of a cooling zone of a continuous heating furnace according to an embodiment of the present invention. [Figure 4] An exemplary cross-sectional schematic diagram of a cross section perpendicular to the direction of travel of the workpiece in a cooling zone of a continuous heating furnace according to one embodiment of the present invention, as viewed from the rear, is shown together with an exemplary schematic diagram of a gas piping system 400. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, the embodiments of the present invention will be described in detail with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate changes and improvements in the design may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0014] <1. Heat storage cooler> 1 is a schematic diagram showing an example of the configuration of a regenerative cooler 100 according to one embodiment of the present invention. The regenerative cooler 100 has a gas nozzle 110 that communicates with the inside of the furnace, a gas port 120 that communicates with the outside of the furnace and is connected to a gas piping system that can switch between supplying air to the regenerative cooler 100 and exhausting air from the regenerative cooler 100, a gas passage 140 that communicates the gas nozzle 110 with the gas port 120 and has a space 143 for filling the regenerative cooler 130, and the regenerative cooler 130 that is filled in the space 143 for filling the regenerative cooler 130.

[0015] The gas passage 140 is configured so that the cooling gas supplied from the gas port 120 passes through the space 143 filled with the heat storage body 130, and then is introduced into the furnace from the gas nozzle 110. The gas passage 140 is also configured so that the furnace gas sucked from the gas nozzle 110 passes through the space 143 filled with the heat storage body 130, and then is discharged from the gas port 120 to the outside of the furnace.

[0016] Therefore, when the furnace gas is supplied from the gas nozzle 110 to the gas passage 140, the furnace gas is cooled by heat exchange with the heat storage body 130. Then, the cooled furnace gas is discharged from the gas port 120 to the outside of the furnace. Meanwhile, the heat storage body 130 that has exchanged heat with the furnace gas is heated. After that, when the supply and exhaust are switched and the cooling gas is supplied from the gas port 120 into the gas passage 140, the cooling gas is heated by heat exchange with the heat storage body 130. Then, the heated cooling gas is supplied from the gas nozzle 110 into the furnace. This makes it possible to make the temperature of the cooling gas supplied from the regenerative cooler 100 into the furnace close to the temperature of the furnace gas.

[0017] As a method for increasing the temperature of the cooling gas supplied from the regenerative cooler 100 to the furnace and reducing the difference with the temperature of the gas in the furnace, for example, a method for increasing the temperature of the heat storage body by lengthening the exhaust time or a method for increasing the amount of filling of the heat storage body can be considered. Conversely, as a method for decreasing the temperature of the cooling gas supplied from the regenerative cooler 100 to the furnace and increasing the cooling capacity, for example, a method for suppressing the temperature rise of the heat storage body by shortening the exhaust time or a method for decreasing the amount of filling of the heat storage body can be considered. In this way, the regenerative cooler 100 can adjust the temperature of the gas in the furnace by a method other than changing the flow rate of the cooling gas. Therefore, particularly in a continuous heating furnace, even if the heat curve in the cooling zone is adjusted, the effect on the furnace pressure in the cooling zone is small, and the gas flow in the furnace can be easily stabilized.

[0018] Although not limited thereto, for example, the temperature of the cooling gas supplied from the gas nozzle 110 of the regenerative cooler 100 into the furnace immediately before it is discharged from the gas nozzle 110 is preferably about 50 to 400°C lower than the average temperature of the gas in the furnace in the case of a batch-type heating furnace (the average temperature of the gas in the furnace at the cooling zone where the regenerative cooler 100 is installed in the case of a continuous heating furnace). Also, the temperature of the exhaust gas discharged from the gas port 120 of the regenerative cooler 100 immediately before it is discharged from the gas port 120 is preferably 110°C or higher to prevent condensation, and more preferably 150°C or higher. The temperature is preferably 350°C or lower, and more preferably 300°C or lower, to protect the equipment. Therefore, the temperature is, for example, preferably 110 to 350°C, and more preferably 150°C to 300°C.

[0019] The heat storage body 130 is not particularly limited, and may be provided in the form of a ball, honeycomb, or mesh. The material of the heat storage body 130 may be appropriately selected in consideration of corrosion resistance and heat resistance, and may be made of, for example, ceramics or metal, and preferably, an optimum material may be selected from ceramics such as SiC-based materials, alumina, cordierite, mullite, and aluminum titanate.

[0020] Although air is generally used as the cooling gas, the cooling gas is not limited to air, and it is also possible to use, for example, inert gases such as N2 and Ar, either singly or in combination.

[0021] In order to prevent the heat storage body 130 from entering the gas port 120, it is preferable to separate the gas port 120 and the heat storage body 130 with a breathable separator 125. In this case, the separator 125 forms the bottom of the space 143 for filling with the heat storage body 130. As the separator 125, for example, a lattice structure or a punching plate made of metal (e.g., SUS) can be used.

[0022] Repeated intake and exhaust causes dust / impurities to accumulate around the heat storage body 130. If this accumulated dust / impurities are accidentally released into the furnace and adhere to the workpiece during transportation, it can cause discoloration. For this reason, it is preferable to provide at least one inlet / outlet 150, 160 for replacing the heat storage body in the heat storage cooler 100 so that the heat storage body 130 can be easily replaced.

[0023] In one embodiment, the gas passage 140 has a first gas passage 141 extending horizontally from the gas nozzle 110, and a second gas passage 142 communicating with the first gas passage 141 and a space 143 for filling the thermal storage body 130 located below the first gas passage 141. The second gas passage 142 preferably extends vertically. In addition, the space 143 for filling the thermal storage body 130 preferably has a tapered portion 144 in which the passage narrows as it approaches the second gas passage 142, for the purpose of making the thermal storage cooler compact while ensuring thermal insulation. Here, the "horizontal direction" in this specification is a concept that includes not only a direction strictly perpendicular to the direction of gravity, but also an approximately horizontal direction. The approximately horizontal direction includes a direction within 20° of the strictly horizontal direction. In addition, the "vertical direction" in this specification is a concept that includes not only a direction strictly parallel to the direction of gravity, but also an approximately vertical direction. The approximately vertical direction includes a direction within 20° of the strictly vertical direction.

[0024] The regenerative cooler 100 having the first gas passage 141 and the second gas passage 142 may have a first inlet / outlet 150 for replacing the regenerative body provided above the second gas passage 142, and a communication passage 151 that communicates the first inlet / outlet 150 with the second gas passage 142. The regenerative body 130 introduced from the first inlet / outlet 150 falls through the communication passage 151 by gravity and can be accommodated in the space 143 via the second gas passage 142. The first inlet / outlet 150 may be provided above the second gas passage 142 and above the first gas passage 141. In this case, the communication passage 151 may communicate the first inlet / outlet 150 with an opening 152 provided in the first gas passage 141, and the first inlet / outlet 150 communicates with the second gas passage 142 via the first gas passage 141. The first access port 150 can be preferably used for refilling the thermal store 130, but may also be used for removing the thermal store 130.

[0025] Moreover, the thermal storage cooler 100 according to one embodiment may have a second inlet / outlet 160 for exchanging the thermal storage material, which is connected to the lower part of the space 143 for filling the thermal storage material 130. The thermal storage cooler 100 according to this embodiment may have a communication passage 161 that communicates the lower part of the space 143 with the second inlet / outlet 160. The "lower part" of the space 143 refers to a part that is lower than half the height H from the lowest point to the highest point of the thermal storage material 130 filled in the space 143 (before the removal operation). The second inlet / outlet 160 is preferably installed at a position that allows access to the thermal storage material 130 filled at the bottom of the space 143. At this time, if the separator 125 is inclined downward toward the communication passage 161, the thermal storage material 130 filled in the space 143 will naturally move to the second inlet / outlet 160 via the communication passage 161 due to gravity, making it easier to remove the thermal storage material 130. The second access port 160 can be preferably used for removing the thermal store 130, but may also be used for refilling the thermal store 130.

[0026] The walls 145 that divide the gas passages 140 are preferably made of a ceramic material such as alumina, mullite, magnesia, etc., from the viewpoints of heat resistance, thermal shock resistance, wear resistance, etc. In particular, the surfaces of the first gas passage 141 and the second gas passage 142 that come into contact with high-temperature gas are preferably made of at least bricks containing the above-mentioned ceramic material. In the regenerative cooler 100 according to the embodiment shown in FIG. 1, the parts made of bricks are surrounded by dotted lines. In the regenerative cooler 100 according to the embodiment shown in FIG. 1, other parts that require heat resistance are made of castable (unshaped refractory) or fiberboard containing the above-mentioned ceramic material.

[0027] In one embodiment, the gas port 120 is connected to an intake fan via piping, and a cooling gas, such as cooling air, can be supplied from the intake fan to the regenerative cooler 100. The gas port 120 is also connected to an exhaust fan via piping, and exhaust air from the regenerative cooler 100 can be sent to the exhaust fan. The supply of cooling gas to the regenerative cooler 100 and the exhaust air from the regenerative cooler 100 can be switched by operating a valve installed, for example, in the middle of the piping.

[0028] <2. Continuous heating furnace> 2 is a schematic side view showing an example of the overall configuration of a continuous heating furnace 10 equipped with a regenerative cooler according to the embodiment described above. The continuous heating furnace 10 is equipped with an entrance 11, a heating zone 12, a cooling zone 13, and an exit 14 in that order, and can heat-treat a workpiece (not shown) loaded on a cart 15 while transporting it from the entrance 11 to the exit 14 within the furnace.

[0029] The heating zone refers to the range in the direction of travel of the work from the entrance of the continuous heating furnace to the heating equipment installed closest to the exit side for heating the inside of the furnace. The cooling zone refers to the range in the direction of travel of the work from just after the heating equipment installed closest to the exit side to the exit of the continuous furnace. The concept of "heating" includes "firing". When manufacturing ceramic products, the heating zone 12 can be divided into a preheating zone 12a where debinding is performed and a firing zone 12b where firing is performed.

[0030] The workpiece is an article to be subjected to heat treatment, and is not particularly limited, but examples thereof include electronic components such as ferrite and ceramic capacitors, semiconductor products, ceramic products, pottery, oxide-based refractories, glass products, metal products, and carbon-based refractories such as alumina-graphite and magnesia-graphite. The continuous heating furnace according to this embodiment can be suitably used when heating the workpiece to 1000°C or higher, typically 1200°C or higher, more typically 1400°C or higher, for example, 1000 to 2000°C.

[0031] There is no particular restriction on the type of continuous heating furnace. For example, it may be a tunnel kiln, a roller hearth kiln, a pusher kiln, etc. In addition, a continuous heating furnace is typically an air firing furnace, and is usually operated without intentionally lowering the oxygen concentration in the furnace, except for the reduction in the oxygen concentration due to burner combustion.

[0032] 3 shows a schematic plan view illustrating a configuration example of the cooling zone 13. The cooling zone 13 includes a plurality of regenerative coolers 100 according to the above-described embodiment, which are capable of introducing cooling gas supplied from an air supply fan into the furnace and exhausting gas in the furnace and sending it to an exhaust fan. Although not limited thereto, the plurality of regenerative coolers 100 can be installed on the furnace wall at a location in the cooling zone 13 where the average temperature of the gas in the furnace is in the range of, for example, 1400°C to 400°C.

[0033] At least one of the multiple regenerative coolers 100 has a gas nozzle 110 on the furnace wall 18 (first inner wall) on the left side with respect to the traveling direction of the workpiece, and at least one of the multiple regenerative coolers 100 has a gas nozzle 110 on the furnace wall 19 (second inner wall) on the right side with respect to the traveling direction of the workpiece. In a preferred embodiment, the multiple regenerative coolers 100 have a gas nozzle 110 on the furnace wall 18 (first inner wall) on the left side with respect to the traveling direction of the workpiece, and the multiple regenerative coolers 100 have a gas nozzle 110 on the furnace wall 19 (second inner wall) on the right side with respect to the traveling direction of the workpiece. The number of regenerative coolers 100 having gas nozzles 110 on the furnace wall 18 (first inner wall) on the left side of the workpiece traveling direction, and the number of regenerative coolers 100 having gas nozzles 110 on the furnace wall 19 (second inner wall) on the right side of the workpiece traveling direction may be set appropriately taking into consideration the cooling speed, furnace length / width, amount of heat removed, etc., and may, for example, be installed every 3 to 10 m in the workpiece traveling direction.

[0034] In order to improve the uniformity of the gas temperature distribution in the furnace in a cross section perpendicular to the direction of travel of the workpiece, a gas nozzle 110 is provided on the furnace wall 18 (first inner wall) on the left side of the direction of travel of the workpiece. Multiple It is preferable to match the number of regenerative coolers 100 with the number of regenerative coolers 100 having gas nozzles 110 on the furnace wall 19 (second inner wall) on the right side with respect to the traveling direction of the work. In order to increase the uniformity of the gas temperature distribution in the furnace in a cross section perpendicular to the traveling direction of the work, it is also preferable to match the installation location in the traveling direction of the work of the regenerative coolers 100 having gas nozzles 110 on the furnace wall 18 (first inner wall) on the left side with respect to the traveling direction of the work with the installation location in the traveling direction of the work of the regenerative coolers 100 having gas nozzles 110 on the furnace wall 19 (second inner wall) on the right side with respect to the traveling direction of the work.

[0035] In one embodiment, at least one, preferably 50% or more, more preferably 80% or more, and even more preferably all of the regenerative coolers 100 having a gas nozzle 110 on the left furnace wall 18 (first inner wall) and at least one, preferably 50% or more, more preferably 80% or more, and even more preferably all of the regenerative coolers 100 having a gas nozzle 110 on the right furnace wall 19 (second inner wall) are configured so that the timing of introducing the cooling gas into the furnace and the timing of sucking the gas in the furnace are reversed. With this configuration, for example, when the cooling gas is introduced into the furnace from at least one regenerative cooler 100 having a gas nozzle 110 on the left furnace wall 18 (first inner wall), the cooling gas crosses the furnace in the left-right direction and is sucked in by at least one regenerative cooler 100 having a gas nozzle 110 on the right furnace wall 19 (second inner wall). This makes it easier for the cooling gas to diffuse left-right and up-down in a cross section perpendicular to the workpiece travel direction within the furnace, contributing to improving the uniformity of the gas temperature distribution within the furnace in a cross section perpendicular to the workpiece travel direction.

[0036] The gas inside the furnace drawn from the regenerative cooler 100 is sent to the exhaust fan by the suction force of the exhaust fan. The exhaust gas from the exhaust fan may be discharged to the atmosphere, but it is advantageous from the viewpoint of energy saving to reuse it to cool a lower temperature workpiece downstream. Therefore, in one embodiment, the cooling zone 13 is provided with one or more cooling gas supply ports 180 capable of introducing the exhaust gas from at least one regenerative cooler 100 into the furnace as a cooling gas, on the side closer to the outlet 14 than the regenerative cooler 100 closest to the outlet 14 among the multiple regenerative coolers 100, preferably only on the side closer to the outlet 14. Each of the one or more cooling gas supply ports 180 is in communication with the gas port 120 of at least one regenerative cooler 100 among the multiple regenerative coolers 100 via an exhaust fan, and the exhaust gas from at least one regenerative cooler 100 can be introduced into the furnace as a cooling gas from the cooling gas supply port 180. Although not limited thereto, one or more cooling gas supply ports 180 can be installed on the furnace wall at a portion of the cooling zone 13 where the average temperature of the furnace gas is in the range of, for example, 150° C. to 600° C. The temperature of the cooling gas supplied into the furnace from the cooling gas supply port 180 immediately before being discharged from the cooling gas supply port 180 is preferably about 50° C. to 250° C. lower than the average temperature of the furnace gas at the portion of the cooling zone 13 where the cooling gas supply port 180 is installed.

[0037] The cooling zone 13 may be provided with one or more outside-furnace air inlets 190 communicating with the outside of the furnace, on the side closer to the outlet 14 than the cooling gas supply port 180 closest to the outlet 14 among the one or more cooling gas supply ports 180, preferably only on the side closer to the outlet 14. The outside-furnace air (typically outside air) can be sucked in by one or more fans 192 and can be supplied into the furnace through a duct or other piping 194. The air that enters the furnace from the outside-furnace air inlet 190 can be used for direct cooling of the workpiece. Although not limited thereto, the one or more outside-furnace air inlets 190 can be installed at a location in the cooling zone where the average temperature of the furnace gas is in the range of, for example, 50°C to 300°C. When the furnace gas temperature is in such a temperature range, the temperature of the workpiece is sufficiently reduced, and there is almost no risk of cracks occurring even if the workpiece is directly cooled using the outside-furnace air. The temperature of the air supplied into the furnace from the outside-furnace air inlet 190 immediately before being discharged from the outside-furnace air inlet 190 is preferably about 50 to 200°C lower than the average temperature of the furnace gas at the location of the cooling zone 13 where the outside-furnace air inlet 190 is installed.

[0038] In order to improve the uniformity of the furnace gas temperature distribution in the cross section perpendicular to the workpiece traveling direction, it is also advantageous to improve the stirring ability of the furnace gas. Therefore, in a preferred embodiment, a plurality of regenerative coolers 100 are arranged so that one or both of the following conditions (1) and (2) are satisfied. (1) At least one of the multiple regenerative coolers 100 has a gas nozzle 110 above half the height of the left furnace wall 18 (first inner wall) in the direction of travel of the workpiece, and at least one of the multiple regenerative coolers 100 has a gas nozzle 110 below half the height of the right furnace wall 19 (second inner wall) in the direction of travel of the workpiece. (2) At least one of the multiple regenerative coolers 100 has a gas nozzle 110 above half the height of the right-side furnace wall 19 (second inner wall) in the direction of travel of the workpiece, and at least one of the multiple regenerative coolers 100 has a gas nozzle 110 below half the height of the left-side furnace wall 18 (first inner wall) in the direction of travel of the workpiece.

[0039] In a preferred embodiment, the cooling gas is introduced into the furnace so that, in addition to one or both of the conditions (1) and (2), one or both of the following conditions (3) and (4) are satisfied. (3) At least one, preferably at least 50% of the total, more preferably at least 80% of the total, and even more preferably all of the regenerative coolers 100 having a gas nozzle 110 above half the height of the left furnace wall 18 (first inner wall), and at least one, preferably at least 50% of the total, more preferably at least 80% of the total, and even more preferably all of the regenerative coolers 100 having a gas nozzle 110 below half the height of the right furnace wall 19 (second inner wall) are configured so that the timing of introducing cooling gas into the furnace and the timing of sucking in the gas in the furnace are reversed. (4) Right furnace wall 1 9 (Part two At least one, preferably 50% or more, more preferably 80% or more, and even more preferably all, of the regenerative coolers 100 have a gas nozzle 110 above half the height of the inner wall of the furnace, and the left furnace wall 1 8 (Part one At least one, preferably at least 50%, more preferably at least 80%, and even more preferably all of the regenerative coolers 100 having a gas nozzle 110 located below half the height of the inner wall are configured so that the timing of introducing cooling gas into the furnace and the timing of sucking in gas from the furnace are reversed. With this configuration, the cooling gas is more likely to flow vertically within the furnace in addition to horizontally, which further contributes to improving the uniformity of the gas temperature distribution within the furnace in a cross section perpendicular to the direction in which the workpiece travels.

[0040] FIG. 4 shows a cooling zone of a continuous heating furnace equipped with at least one first regenerative cooler 100a having a gas nozzle 110 above half the height of the furnace wall 18 (first inner wall) on the left side with respect to the traveling direction of the work 600, and at least one second regenerative cooler 100b having a gas nozzle 110 below half the height of the furnace wall 19 (second inner wall) on the right side with respect to the traveling direction of the work 600. ofAn exemplary schematic cross-sectional view as viewed from the rear with respect to the traveling direction of the workpiece 600 is shown together with an exemplary schematic view of the gas piping system 400. Note that half the height of the furnace wall (first inner wall or second inner wall) means a position half the height from the hearth 21 to the ceiling 22 along the furnace wall (first inner wall or second inner wall) at the location where the first regenerative cooler 100a or the second regenerative cooler 100b is installed.

[0041] A large number of workpieces 600 can be loaded onto multiple shelves 520 installed on a kiln tool 500 placed on a cart 15.

[0042] An air supply fan 410 is installed in the middle of the pipe 452 through which a cooling gas such as air outside the furnace flows. The pipe 452 branches into a pipe 452a connected to the gas port 120 of the first regenerative cooler 100a and a pipe 452b connected to the gas port 120 of the second regenerative cooler 100b downstream of the air supply fan 410. Air supply valves 428a and 428b are installed in the middle of the pipe 452a and the pipe 452b, respectively. The pipe 452a branches into a pipe 453a in the middle, and the pipe 452b branches into a pipe 453b in the middle. Exhaust valves 428c and 428d are installed in the middle of the pipe 453a and the pipe 453b, respectively. The pipe 453a and the pipe 453b merge with the pipe 453 downstream of the exhaust valves 428c and 428d. An exhaust fan 420 is installed in the middle of the pipe 453.

[0043] FIG. 4 shows a state in which the first regenerative cooler 100a is in a supply mode in which cooling gas is supplied into the furnace, while the second regenerative cooler 100b is in an exhaust mode in which gas in the furnace is exhausted. Switching between air supply and exhaust is performed between the first regenerative cooler 100a and the second regenerative cooler 100b every certain time. By switching, the first regenerative cooler 100a, which was previously in the supply mode, goes into the exhaust mode, and the second regenerative cooler 100b, which was previously in the exhaust mode, goes into the supply mode. This switching can be performed by reversing the open / closed state of the air supply valves 428a, 428b and the exhaust valves 428c, 428d. The switching between air supply and exhaust can be repeated at predetermined time intervals, which can be, for example, 10 to 300 seconds.

[0044] In FIG. 4, two-way valves are shown as the air supply valves 428a, 428b and the exhaust valves 428c, 428d, but three-way valves may also be used. Electrically driven valves such as solenoid valves may be used as the valves. In addition, in FIG. 4, one each of the first and second heat storage coolers 100a and 100b is shown installed, but it is preferable to arrange a plurality of the first and second heat storage coolers 100a and 100b in parallel in the direction of travel of the work. For example, by branching the piping 452a and arranging a plurality of first heat storage coolers 100a in parallel, it is possible to switch the supply and exhaust for a plurality of first heat storage coolers 100a collectively. Similarly, by branching the piping 452b and arranging a plurality of second heat storage coolers 100b in parallel, it is possible to switch the supply and exhaust for a plurality of second heat storage coolers 100b collectively. In addition, an exhaust pipe and an air supply pipe may be prepared independently and connected to the gas port 120, respectively.

[0045] Although a continuous heating furnace has been described in the above embodiment, the mechanism is the same in a batch heating furnace, and it will be understood that the installation of a regenerative cooler has the effect of reducing the risk of cracks occurring in the workpiece and improving the uniformity of the gas temperature distribution inside the furnace. [Explanation of symbols]

[0046] 10: Continuous heating furnace 11: Entrance 12: Heating zone 12a: Pre-tropical zone 12b: Firing zone 13: Cooling zone 14:Exit 15: Cart 18: Furnace wall (first inner wall) 19: Furnace wall (second inner wall) 21: Hearth 22: Ceiling 100: Heat storage cooler 100a: First heat storage cooler 100b:Second heat storage cooler 110: Gas nozzle 120: Gas port 125: Separator 130: Heat storage body 140: Gas passage 141: First gas passage 142: Second gas passage 143:Space 144: Tapered section 145: Wall 150:First entrance / exit 151:Communication path 152 :Aperture 160:Second entrance 161: Communication path 180: Cooling gas supply port 190: Furnace air inlet 192: Fan 194: Piping 400: Gas piping system 410: Supply air fan 420: Exhaust fan 428a: Air supply valve 428b: Air supply valve 428c: Exhaust valve 428d: Exhaust valve 452: Piping 452a :Plumbing 452b :Plumbing 453: Piping 453a :Plumbing 453b :Plumbing 500: Kiln tools 520: Shelf 600: Work

Claims

1. A heating furnace capable of introducing a cooling gas into the furnace and having a plurality of regenerative coolers capable of sucking gas in the furnace, Each of the plurality of regenerative coolers has a gas nozzle communicating with the inside of the furnace, a gas port communicating with the outside of the furnace and connected to a gas piping system capable of switching between supplying air to the regenerative cooler and exhausting air from the regenerative cooler, a gas passage communicating the gas nozzle with the gas port and having a space for filling the regenerative cooler, and a regenerative cooler filled in the space for filling the regenerative cooler, and is not configured to be supplied with gas as a fuel. Heating furnace.

2. The heating furnace is a continuous heating furnace having an inlet, a heating zone, a cooling zone, and an outlet in this order, for heat-treating at least one workpiece while transporting it from the inlet to the outlet in the furnace, The cooling zone is provided with the plurality of heat storage coolers. The heating furnace according to claim 1 .

3. 3. A heating furnace as claimed in claim 1 or 2, wherein at least one of said plurality of regenerative coolers has at least one port for exchange of regenerative mass.

4. A heating furnace capable of introducing a cooling gas into the furnace and having a plurality of heat storage coolers capable of sucking in the gas in the furnace, Each of the plurality of regenerative coolers has a gas nozzle communicating with the inside of the furnace, a gas port communicating with the outside of the furnace and connected to a gas piping system capable of switching between supplying air to the regenerative cooler and exhausting air from the regenerative cooler, a gas passage communicating the gas nozzle with the gas port and having a space for filling a regenerative body, and a regenerative body filled in the space for filling the regenerative body, At least one of the plurality of storage coolers is a gas passage including a first gas passage extending horizontally from the gas nozzle and a second gas passage communicating with the first gas passage a space for filling the heat storage body located below the first gas passage; a first inlet / outlet for replacing the heat storage medium provided above the second gas passage; a communication passage that communicates the first port with a second gas passage; A heating furnace having a

5. 4. The heating furnace of claim 3, wherein at least one of said plurality of regenerative coolers has a second access for replacing the regenerative heat storage medium, said second access opening communicating with a lower portion of said space for filling said regenerative heat storage medium.

6. 3. A heating furnace according to claim 1 or 2, wherein the heat reservoir is in the form of a ball, a honeycomb or a mesh.

7. 3. The heating furnace of claim 1, wherein at least one of the plurality of regenerative coolers has the gas nozzle on a first inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle on a second inner wall opposite the first inner wall.

8. A heating furnace capable of introducing a cooling gas into the furnace and having a plurality of heat storage coolers capable of sucking in the gas in the furnace, Each of the plurality of regenerative coolers has a gas nozzle communicating with the inside of the furnace, a gas port communicating with the outside of the furnace and connected to a gas piping system capable of switching between supplying air to the regenerative cooler and exhausting air from the regenerative cooler, a gas passage communicating the gas nozzle with the gas port and having a space for filling a regenerative body, and a regenerative body filled in the space for filling the regenerative body, At least one of the plurality of regenerative coolers has the gas nozzle on a first inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle on a second inner wall opposite the first inner wall; A heating furnace that satisfies one or both of the following conditions (1) and (2). (1) At least one of the plurality of regenerative coolers has the gas nozzle above half the height of the first inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle below half the height of the second inner wall. (2) At least one of the plurality of regenerative coolers has the gas nozzle above half the height of the second inner wall, and at least one of the plurality of regenerative coolers has the gas nozzle below half the height of the first inner wall.

9. 8. The heating furnace of claim 7, wherein the number of regenerative coolers having the gas nozzles on the first inner wall is equal to the number of regenerative coolers having the gas nozzles on the second inner wall.

10. 8. The heating furnace according to claim 7, wherein at least one regenerative cooler having the gas nozzle on the first inner wall and at least one regenerative cooler having the gas nozzle on the second inner wall are configured so that the timing of introducing the cooling gas into the furnace and the timing of sucking in the gas in the furnace are reversed.

11. A heating furnace having a plurality of heat storage coolers capable of introducing a cooling gas into the furnace and sucking the gas in the furnace, The heating furnace is a continuous heating furnace which sequentially includes an inlet, a heating zone, a cooling zone, and an outlet, and which heat-treats at least one workpiece while transporting it from the inlet to the outlet in the furnace, and which includes the plurality of regenerative coolers in the cooling zone; Each of the plurality of regenerative coolers has a gas nozzle communicating with the inside of the furnace, a gas port communicating with the outside of the furnace and connected to a gas piping system capable of switching between supplying air to the regenerative cooler and exhausting air from the regenerative cooler, a gas passage communicating the gas nozzle with the gas port and having a space for filling a regenerative body, and a regenerative body filled in the space for filling the regenerative body, A heating furnace, wherein the cooling zone is provided with one or more cooling gas supply ports capable of introducing cooling gas into the furnace, located closer to the outlet than the heat storage cooler closest to the outlet among the plurality of heat storage coolers, and each of the one or more cooling gas supply ports is connected to the gas port of at least one of the plurality of heat storage coolers, and is configured so that exhaust from the at least one heat storage cooler can be introduced into the furnace as cooling gas from the cooling gas supply port.

12. The heating furnace according to claim 11, wherein the cooling zone is provided with one or more outside-furnace air inlet ports communicating with the outside of the furnace, located closer to the outlet than the cooling gas supply port closest to the outlet among the one or more cooling gas supply ports.

13. 3. The heating furnace according to claim 1 or 2, which is a baking furnace.

Images