Industrial furnace and method for heat treatment of workpieces using this industrial furnace

Abstract

The present invention provides a novel industrial furnace capable of effectively preventing the release of dioxins into the atmosphere, and a method for heat-treating a workpiece using this industrial furnace. [Solution] The furnace is equipped with a combustion chamber 25 and carbonization boxes 16, 17 and a combustion chamber 25, which are arranged inside the heating chamber 15 and contain the material to be processed, a combustion burner 32 for heating the inside of the combustion chamber 25, a carbonization gas burner 31 that uses carbonization gas as fuel, a re-combustion furnace 3 whose interior is a re-combustion chamber 3d, a re-combustion burner 44 for heating the inside of the re-combustion chamber 3d, a temperature measuring means 41 for measuring the internal temperature of the re-combustion chamber 3d, and an exhaust pipe 43 for releasing the gas burned in the re-combustion chamber 3d into the atmosphere. The furnace is equipped with a re-combustion pipeline 48 that supplies carbonization gas generated in the carbonization boxes 16, 17 into the re-combustion chamber 3 by driving the combustion burner 32, which is started to drive after the temperature inside the re-combustion chamber 3d, as measured by the temperature measuring means 41, reaches 800 degrees Celsius or higher due to the driving of the re-combustion burner 44, and then driving the carbonization gas generated in the carbonization boxes 16, 17 into the re-combustion chamber 3.

Description

Technical Field

[0001] The present invention relates to a carbonization furnace, an incinerator, and other industrial furnaces, and a method for heat-treating a workpiece using such an industrial furnace.

Background Art

[0002] Various industrial furnaces such as carbonization furnaces (pyrolysis furnaces) and incinerators are used to pyrolyze a workpiece accommodated in the industrial furnace by means of a burner. The workpiece is for heat-treating waste containing organic substances. Particularly in recent years, in order to recover valuable substances such as lithium, nickel, or cobalt contained in a lithium-ion battery as the workpiece, it is not uncommon to pyrolyze the workpiece using a carbonization furnace, which is one of the above industrial furnaces.

[0003] Conventionally, as the above carbonization furnace (industrial furnace), the one disclosed in Japanese Patent Application Laid-Open No. 2022-164399 (Patent Document 1) has been proposed. This carbonization furnace includes a combustion chamber formed on the lower surface side of the side of the carbonization furnace and having a length in the horizontal direction, and a combustion burner for heating the inside of the combustion chamber to a high temperature is disposed outside the carbonization furnace. This combustion burner burns fossil fuel (kerosene or gas), and the tip side of the combustion burner is located inside the combustion chamber. Further, in the vicinity of the combustion chamber, a heating chamber is provided in which a workpiece accommodated in a box-shaped container is disposed, and the workpiece is carbonized (pyrolyzed or heat-treated) by the heat in the combustion chamber. And, one end of a dry distillation gas flow path including a dry distillation gas duct communicating with the inside of the container is fixed to the container in which the workpiece is accommodated, and the other end of the dry distillation gas flow path is connected to a dry distillation gas burner (blower). This dry distillation gas burner (blower) uses the dry distillation gas generated when the workpiece is heat-treated as fuel. By using the dry distillation gas burner (blower) separately from the combustion burner (as a component of the carbonization furnace), the fuel cost during use is reduced.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-164399 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, in many carbonization furnaces, including the carbonization furnace disclosed in Patent Document 1, when waste containing organic matter is heat-treated, toxic dioxins and dioxin compounds (hereinafter referred to as dioxins) are generated as by-products. When these dioxins are released into the atmosphere, they bind to particles in the atmosphere and fall to the ground, contaminating soil and water. Over long periods, they are taken up by plankton and marine life through the food chain, accumulating in living organisms and thus having adverse effects on the natural environment and human health. In particular, these dioxins are easily generated during the process of thermal decomposition of the material being treated at low temperatures, and are especially likely to be generated during incomplete combustion immediately after ignition. In other words, in the carbonization furnace disclosed in Patent Document 1, the carbonization gas generated in the container is supplied to the carbonization gas burner from the carbonization gas flow path. However, if the combustion chamber is still at a low temperature, the dioxins contained in the carbonization gas are not burned at high temperatures and are released into the atmosphere.

[0006] Therefore, the present invention was proposed to solve the problems of the conventional carbonization apparatus (industrial furnace) described above, and aims to provide a novel industrial furnace that can effectively prevent the release of dioxins into the atmosphere, and a method for heat-treating a workpiece using this industrial furnace. [Means for solving the problem]

[0007] The present invention was proposed to solve the above problems, and the first invention (the invention described in claim 1) relates to an industrial furnace and is characterized by comprising: a heating chamber whose interior is heated; a carbonization box placed in the heating chamber and containing a workpiece to be processed that contains organic matter; a combustion chamber placed adjacent to the heating chamber; a combustion burner for heating the combustion chamber; a carbonization gas burner placed near the combustion burner and fueled by carbonization gas generated by heating the workpiece; a re-combustion furnace whose interior is a re-combustion chamber; a re-combustion burner for heating the re-combustion chamber; a temperature measuring means for measuring the internal temperature of the re-combustion chamber; an exhaust pipe for releasing the gas burned in the re-combustion chamber into the atmosphere; and a re-combustion pipeline for supplying carbonization gas generated in the carbonization box into the re-combustion chamber by driving the combustion burner, which is started to drive after the temperature in the re-combustion chamber, as measured by the temperature measuring means, reaches 800 degrees Celsius or higher due to the driving of the re-combustion burner.

[0008] The industrial furnace according to this first invention, in addition to the basic configuration of a conventional industrial furnace, comprises a re-combustion furnace with a re-combustion chamber inside, a re-combustion burner for heating the inside of the re-combustion chamber, a temperature measuring means for measuring the internal temperature of the re-combustion chamber, an exhaust pipe for releasing the gas re-combusted in the re-combustion chamber into the atmosphere, and a re-combustion pipeline for supplying the carbonization gas generated in the carbonization box into the re-combustion chamber by driving the combustion burner, which is started to drive after the temperature inside the re-combustion chamber, as measured by the temperature measuring means, reaches 800 degrees Celsius or higher. In the industrial furnace according to this first invention, the temperature in the re-combustion chamber rises when the re-combustion burner is driven, and when the combustion burner is started after the temperature in the re-combustion chamber reaches 800 degrees Celsius or higher as measured by the temperature measuring means, the heat from this combustion burner supplies the carbonization gas generated in the carbonization box (particularly gas generated in a temperature atmosphere where the temperature in the combustion chamber is less than 800 degrees Celsius and contains dioxins) into the re-combustion chamber via the re-combustion pipeline. In this re-combustion chamber, the carbonization gas is re-combusted at 800 degrees Celsius or higher and then released (exhausted) into the atmosphere through the exhaust pipe. Therefore, according to this invention, it is possible to effectively prevent the release of gas containing dioxins into the atmosphere.

[0009] The above-mentioned re-combustion pipeline supplies the carbonization gas generated in the carbonization box (particularly gas generated in a temperature atmosphere where the temperature in the combustion chamber, the heating chamber, or the carbonization box is less than 800 degrees Celsius, and which contains dioxins) into the re-combustion chamber. On the other hand, the carbonization gas burner uses the carbonization gas generated by the heating of the material to be processed as fuel. Therefore, the carbonization box and the carbonization gas burner are supplied via another pipeline (a carbonization gas pipeline constituting the second invention) that supplies the carbonization gas from the carbonization box to the carbonization gas burner. However, in this first invention, the above-mentioned re-combustion pipeline and the above-mentioned other pipeline (a carbonization gas pipeline constituting the second invention) may be separate and independent.

[0010] Furthermore, the second invention (the invention described in claim 2) is characterized in that, in the first invention, a carbonization gas pipeline for supplying the carbonization gas to the carbonization gas burner is connected to the middle of the re-combustion pipeline, and a switching valve for switching the destination of the carbonization gas to either the re-combustion chamber or the carbonization gas burner is arranged in the middle of the re-combustion pipeline or the carbonization gas pipeline.

[0011] In this second invention, the intermediate section of the re-combustion pipeline is connected to the carbonization gas pipeline that supplies the carbonization gas to the carbonization gas burner. Therefore, the carbonization gas generated in the carbonization box can be supplied to the re-combustion chamber and also to the carbonization gas burner at the intermediate section of the re-combustion pipeline. Furthermore, in this second invention, a switching valve is provided at the intermediate section of either the re-combustion pipeline or the carbonization gas pipeline to switch the supply destination of the carbonization gas to either the re-combustion chamber or the carbonization gas burner. Therefore, the supply destination of the carbonization gas can be selectively changed by switching the switching valve. Accordingly, according to the industrial furnace of this second invention, the re-combustion pipeline and the other pipeline (the carbonization gas pipeline constituting this second invention) can be manufactured at a lower cost compared to separate and independent pipelines.

[0012] Furthermore, the third invention (the invention described in claim 3) is characterized in that, in the second invention, other temperature measuring means are provided in the combustion chamber, and the switching valve is switched so that the carbonization gas is supplied to the carbonization gas burner after the temperature in the combustion chamber, as measured by the other temperature measuring means, reaches 800 degrees Celsius or higher.

[0013] In the industrial furnace according to this third invention, when the temperature in the combustion chamber reaches 800 degrees Celsius or higher as measured by the other temperature measuring means, the switching valve switches the supply of the carbonization gas, which had previously been exclusively supplied to the re-combustion chamber via the re-combustion pipeline, to the carbonization gas burner. When the temperature in the combustion chamber reaches 800 degrees Celsius or higher, the possibility of dioxins being present in the carbonization gas is considerably low, and there is no need to re-combust it in the re-combustion chamber. In other words, the carbonization gas can be used as fuel for the carbonization gas burner, just like in a conventional industrial furnace. Furthermore, since the combustion chamber is heated to a temperature considerably above 800 degrees Celsius by the operation of the carbonization gas burner, gas containing dioxins is not released into the atmosphere. When the carbonization gas is switched to be supplied to the carbonization gas burner in this manner, the operation of the re-combustion burner, which had been running until then, is stopped.

[0014] Furthermore, the fourth invention (the invention described in claim 4) relates to a method for heat-treating a workpiece using an industrial furnace, comprising: a heating chamber whose interior is heated; a carbonization box placed inside the heating chamber and containing a workpiece containing organic matter; a combustion chamber located adjacent to the heating chamber; a combustion burner for heating the combustion chamber; a carbonization gas burner located near the combustion burner and fueled by the carbonization gas generated when the workpiece is heated; a re-combustion furnace whose interior is a re-combustion chamber; a re-combustion burner for heating the re-combustion chamber; a temperature measuring means for measuring the internal temperature of the re-combustion chamber; and the gas burned in the re-combustion chamber. A heat treatment method for an object to be treated using an industrial furnace, comprising an exhaust pipe for releasing the body into the atmosphere and a re-combustion pipeline for supplying the carbonized gas generated in the carbonization box into the re-combustion chamber, characterized in that it comprises a re-combustion chamber heating step of heating the re-combustion chamber with the re-combustion burner, a combustion chamber heating step of heating the heating chamber with the combustion burner after the temperature in the re-combustion chamber, as measured by the temperature measuring means, reaches 800 degrees Celsius or higher, and a carbonized gas re-combustion step of supplying the carbonized gas generated in the carbonization box by the combustion chamber heating step into the re-combustion chamber via the re-combustion pipeline.

[0015] Further, the fifth invention (the invention according to claim 5) is the same as the fourth invention described above, except that in the combustion chamber, other temperature measuring means is provided, and after the temperature in the combustion chamber measured by this other temperature measuring means reaches 800 degrees Celsius or more, the dry distillation gas reburning process is stopped, and a flow path switching process of supplying the dry distillation gas generated in the carbonization box exclusively to the dry distillation gas burner is provided.

[0016] Since the fifth invention described above is substantially the same as the first invention described above, and the fifth invention is substantially the same as the third invention described above, the description of the steps of each invention and the effects of such steps will be omitted.

Effects of the Invention

[0017] According to each of the above inventions, it is possible to effectively prevent dioxins generated at a stage where the object to be treated containing organic substances is heat-treated at a temperature less than 800 degrees Celsius, that is, at a stage before a predetermined time has elapsed after the driving of the combustion burner is started, from being released into the atmosphere.

Brief Description of the Drawings

[0018] [Figure 1] It is a front view of a carbonization furnace according to an embodiment of the present invention. [Figure 2] It is a rear view of the carbonization furnace shown in FIG. 1. [Figure 3] It is a left side view of the carbonization furnace shown in FIG. 1. [Figure 4] It is a right side view of the carbonization furnace shown in FIG. 1. [Figure 5] It is a plan view of the carbonization furnace shown in FIG. 1. [Figure 6] It is a front cross-sectional view showing the internal structure on the rear side of the carbonization furnace shown in FIG. 1. [Figure 7] It is a front cross-sectional view showing the internal structure on the front side of the carbonization furnace shown in FIG. 1. [Figure 8] It is a right cross-sectional view of the carbonization furnace shown in FIG. 1. [Figure 9]It is a left cross-sectional view showing the internal structure of the reburning furnace. [Figure 10] It is a front cross-sectional view showing the reburning furnace main body.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the industrial furnace according to the best mode for carrying out the present invention will be described in detail with reference to the drawings. Note that this embodiment applies the industrial furnace according to the present invention to a carbonization furnace. First, the configuration of the carbonization furnace will be described, then each operation performed by the carbonization furnace will be described step by step, and the effects of each step will be explained.

[0020] As shown in FIG. 1, this carbonization furnace 1 includes a carbonization furnace main body 2 formed in a rectangular parallelepiped shape with an overall outer shape having a length in the horizontal direction, and a reburning furnace 31 (described later) connected to the carbonization furnace main body 2. And as shown in FIG. 6 or FIG. 7, the carbonization furnace main body 2 includes a bottom portion 4 formed in a substantially rectangular shape, a left wall portion 5 standing up from the left end of the bottom portion 4, a right wall portion 6 standing up from the right end of the bottom portion 4 and facing the left wall portion 5, and a front wall portion 7 (see FIG. 1) standing up from the front end of the bottom portion 4. Further, this carbonization furnace 1 includes a rear wall portion 8 (see FIG. 2) standing up from the rear end of the bottom portion 4 and facing the front wall portion 7, and a ceiling portion 9 (see FIG. 5). Note that inside the upper surface of the bottom portion 4, the left wall portion 5, the right wall portion 6, the front wall portion 7, the rear wall portion 8, and the ceiling portion 9, a heat insulating material (reference numerals are omitted) made of an inorganic material such as heat insulating tiles or heat insulating wool is fixed. In addition, rectangular openings (reference numerals are omitted) are respectively formed on the left and right sides of the front wall portion 7. As shown in FIG. 1, the left opening is closed by a left opening / closing door 10, and the right opening is closed by a right opening / closing door 11.

[0021] Furthermore, as shown in Figure 6 or Figure 7, a heating chamber 15 is provided inside the carbonization furnace body 2, and as shown in Figure 7, first and second carbonization boxes 16 and 17 are arranged in the heating chamber 15. These first and second carbonization boxes 16 and 17 are each molded into a box shape and are supported by the upper ends of a plurality of support columns (not shown) that rise up from the bottom 4, and their front sides are open. The front side of the first carbonization box 16 is closed by the left opening / closing door 10, and the front side of the second carbonization box 17 is closed by the right opening / closing door 11. When the openings formed on the front of the first carbonization box 16 and the second carbonization box 17 are closed by the left opening / closing door 10 or the right opening / closing door 11, the inside of the first and second carbonization boxes 16 and 17 becomes a sealed space. As shown in Figure 7, multiple carbonization containers 20 are housed in the first and second carbonization boxes 16 and 17, stacked vertically or otherwise. These carbonization containers 20 contain materials to be processed (not shown). These carbonization containers 20 are brought into and stacked in the first and second carbonization boxes 16 and 17, which are opened by opening the left opening door 10 and the right opening door 11. When the carbonization process by the carbonization furnace body 2 is completed, the left opening door 10 and the right opening door 11, which were previously closed, are opened, and the containers are removed from the first and second carbonization boxes 16 and 17 to the outside.

[0022] Furthermore, as shown in Figure 7, the first carbonization box 16 and the second carbonization box 17 are connected to each other by a connecting pipe 21, and the interiors of the first carbonization box 16 and the second carbonization box 17 are in communication with each other. In addition, one end of a carbonization gas transfer pipeline 22, which consists of multiple pipes (reference numerals omitted), is fixed to the left wall 16a of the first carbonization box 16, and the middle part of the carbonization gas transfer pipeline 22 is inserted into an opening (not shown) formed in the left wall 5, while the other end of the carbonization gas transfer pipeline 22 is located outside the carbonization furnace body 2 and is connected to the first four-way cross pipe 23. The carbonization gas transfer pipeline 22 is through which the carbonization gas generated by the carbonization treatment (thermal decomposition or heat treatment) of the material to be treated in the first and second carbonization boxes 16 and 17 flows.

[0023] Furthermore, as shown in Figure 6, a combustion chamber 25 is formed inside the carbonization furnace body 2 along the length of the rear wall 8. As shown in Figure 8, this combustion chamber 25 is surrounded by the inner surface 25a at the lower end of the rear wall 8, a partition 25c that faces the top plate 25b and the inner surface 25a at the lower end of the rear wall 8, and an insulating floor 25d fixed to the upper surface of the bottom 4. As shown in Figure 6, this is a space that extends from the left wall 5 to the right wall 6 of the carbonization furnace 1. On the right wall 6 side of the combustion chamber 25, a rear exhaust pipe 26 is formed, which communicates with the combustion chamber 25 and is shaped like an L. The upper end of the rear exhaust pipe 26 is connected to the lower end of a main duct 27 that has length in the vertical direction and consists of multiple ducts (reference numerals omitted) connected vertically. An opening (notation omitted) is formed at the upper end of the main duct 27 through which gas is released into the atmosphere. A branch pipe section 27b is formed in the base end duct 27a located at the lowest end of the main duct 27, as shown in Figure 6 or Figure 1. One end of this branch pipe section 27b communicates with the base end duct 27a, and the other end communicates with the heating chamber 15 through an opening (notation omitted) formed in the right wall 6 of the carbonization furnace body 2. In other words, the combustion chamber 25 and the heating chamber 15 are connected via the branch pipe section 27b. Furthermore, an opening / closing damper 27c is located inside the lower end of the main duct 27, above the position of the base end duct 27a, as shown in Figure 6. Furthermore, as shown in Figure 7 or Figure 8, the upper surface of the top plate portion 25b constituting the combustion chamber 25 is located slightly above the lower surfaces of the first and second carbonization boxes 16 and 17. As shown in Figure 6, a first thermocouple 28 for measuring the temperature inside the combustion chamber 25 is arranged on the rear wall portion 8 constituting the combustion chamber 25. This first thermocouple 28 is another temperature measuring means constituting the present invention.

[0024] Furthermore, as shown in Figure 6, a refractory molded member 29, made of a refractory material such as alumina (aluminum oxide) and with its inner surface facing the combustion chamber 25, is fixed to the lower rear side of the left wall portion 5. This refractory molded member 29 has one cylindrical opening 29a and another opening 29b formed below the first opening 29a. The first carbonization gas burner 31 is fixed with its tip inserted into the first opening 29a, and the combustion burner 32 is fixed with its tip inserted into the other opening 29b. The first carbonization gas burner 31 uses carbonization gas generated by carbonization (thermal decomposition or heat treatment) of the material to be processed in the first and second carbonization boxes 16 and 17 as fuel, as will be described later. Furthermore, as shown in Figure 1 or Figure 6, a second four-way cross pipe 33, which will be described later, is fixed to the base end of the first carbonization gas burner 31. The combustion burner 32 uses natural gas as the combustion material and is a gas burner that has been used in general carbonization furnaces until now. It is equipped with a fan (not shown), a damper, a manifold, a pilot burner, and a gas supply passage whose base end is connected to a gas pipe, etc., located in the air transfer passage of the fan.

[0025] Furthermore, as shown in Figure 7 or Figure 8, an exhaust chamber 34 is formed inside the carbonization furnace body 2, on the inside of the front wall 7. This exhaust chamber 34 is parallel to the combustion chamber 25, and on the left side of the exhaust chamber 34, on the right wall 6 side, a front exhaust pipe 35 is formed in an L-shape and communicates with the exhaust chamber 34. The lower end of a front exhaust duct 36, to which multiple ducts are connected, is fixed to the upper end of the front exhaust pipe 35. The upper end of the front exhaust duct 36 is curved in an arc and connected to the middle of the main duct 27. The position where the front exhaust duct 36 is connected to the main duct 27 is above the position where the opening / closing damper 27c shown in Figure 6 is located, and below the position where the exhaust pipe 43, which will be described later, is connected to the main duct 27. Furthermore, as shown in Figure 7, the left side of the exhaust chamber 34 is in communication with the heating chamber 15 through an opening (the reference numeral is omitted).

[0026] As described above, the carbonization furnace body 2 is equipped with the re-combustion furnace 3 described at the beginning, as shown in Figures 1 to 6. As shown in Figure 6 or 8, the re-combustion furnace 3 comprises a cylindrical section 3a formed into a cylindrical shape, a left cylindrical plate 3b fixed to the left end of the cylindrical section 3a (in Figure 6), and a right cylindrical plate 3c fixed to the right end of the cylindrical section 3a (in Figure 6), with the interior forming a re-combustion chamber 3d. A refractory material such as alumina is fixed to the inside of the re-combustion furnace 3. Furthermore, as shown in Figure 10, a second thermocouple 41 for measuring the temperature inside the re-combustion chamber 3d is positioned in the cylindrical section 3a. This second thermocouple 41 is a temperature measuring means that constitutes the present invention. Furthermore, as shown in Figure 8, an exhaust pipe section 3e is formed in the re-combustion furnace 3 at the middle of the right end of the cylindrical section 3a, at an eccentric position from the center when viewed from the right side of the cylindrical section 3a (from 12 o'clock to 2 o'clock on a clock face), and the base end of the exhaust pipe 43 is connected to this exhaust pipe section 3e. The tip of this exhaust pipe 43 is connected to the middle of the upper end of the main duct 27, as shown in Figures 1 to 4. Also, as shown in Figure 9, a first burner conduit 3f is formed on the left end of the cylindrical section 3a, and the tip of the re-combustion burner 44 is inserted and fixed inside this first burner conduit 3f. This re-combustion burner 44 uses natural gas as the combustion material and is a gas burner that has been used in general carbonization furnaces until now. Furthermore, the first burner conduit 3f is oriented eccentrically from the center of the cylindrical portion 3a so that the flame from the re-combustion burner 44 irradiates the inner circumference of the cylindrical portion 3a. In addition, a second burner conduit 3g is formed in a clockwise direction from the formation position of the first burner conduit 3f to the cylindrical portion 3a. The tip of the second carbonization gas burner 45 is inserted and fixed into this second burner conduit 3g.Therefore, the flame from the re-combustion burner 44 is radiated clockwise in Figure 9 within the cylindrical section 3a, and the carbonized gas radiated from the second carbonized gas burner 45 is also radiated clockwise in Figure 9. Within the re-combustion chamber 3d, the entire carbonized gas is burned in a swirling manner, and then passes through the exhaust pipe section 3e shown in Figure 8, through the exhaust pipe 43, through the main duct 27, and is released into the atmosphere.

[0027] Furthermore, the base end of the second carbonization gas burner 45 and the first four-way cross pipe 23 are connected by a re-combustion pipeline 48 via a first valve-integrated pipe 47, which has a first switching valve built in between, as shown in Figure 1 or Figure 2. In addition, the first four-way cross pipe 23 and the second four-way cross pipe 33, which is fixed to the base end of the first carbonization gas burner 31, are connected by a connecting pipe 51 via a second valve-integrated pipe 50, which has a second switching valve built in between. The first four-way cross pipe 23 has first to fourth connection parts (reference numerals omitted). The other end of the carbonization gas transfer pipeline 22 is fixed to the first connection part formed in the first four-way cross pipe 23. The lower end of the first valve-integrated pipe 47, whose upper end is connected to the lower end of the re-combustion pipeline 48, is fixed to the second connection part. The third connection part is closed by a blocking plate (reference numerals omitted). The upper end of the connecting pipe 51 is fixed to the fourth connection part formed below the first connection part. The second four-way cross pipe 33 also has first to fourth connection parts (reference numerals omitted). The base end of the first carbonization gas burner 31 is fixed to the first connection part formed in the second four-way cross pipe 33. The lower end of the second valve-integrated pipe 50, whose upper end is fixed to the lower end of the connecting pipe 51, is fixed to the second connection part. Furthermore, the third connection portion is closed by a blocking plate (the reference numeral is omitted), and the fourth connection portion formed below the first connection portion is also closed by a blocking plate (the reference numeral is omitted).

[0028] The carbonization furnace 1 according to this embodiment described above is driven through various processes described below. Therefore, these processes will be explained in order below, along with the effects of each process.

[0029] First, the re-combustion burner 44 is started. By operating this re-combustion burner 44, the temperature of the re-combustion chamber 3d formed in the re-combustion furnace 3 is heated (re-combustion chamber heating process). In this case, the first switching valve built into the first valve-built-in pipe 47 and the second switching valve built into the second valve-built-in pipe 50 are both closed. Then, as the temperature inside the re-combustion chamber 3d gradually rises due to the re-combustion chamber heating process, when the temperature inside the re-combustion chamber 3d reaches 800 degrees Celsius or higher, the combustion burner 32 is started to heat the heating chamber 15 (combustion chamber heating process), and the first switching valve, which had been closed until then, is opened. Whether or not the temperature inside the re-combustion chamber 3d has reached 800 degrees Celsius or higher is determined by the measurement result of the second thermocouple (temperature measuring means) 41. As a result, the temperature inside the combustion chamber 25 rises, and the gas heated in the combustion chamber 25 passes through the branch pipe section 27b and flows into the heating chamber 15. This influx of gas into the heating chamber 15 raises the temperature inside the heating chamber 15, which in turn heats the first and second carbonization boxes 16 and 17 located inside the heating chamber 15, causing the material to be carbonized. Before this combustion chamber heating process is performed, the opening / closing damper 27c located at the top of the base end duct 27a may be kept closed. Closing the opening / closing damper 27c effectively raises the temperature inside the heating chamber 15. Furthermore, as the carbonization boxes 16 and 17 inside the first and second carbonization boxes 16 and 17 are heated, the material to be carbonized inside the carbonization container 20 is gradually carbonized, and carbonization gas is generated inside the first and second carbonization boxes 16 and 17. The carbonized gas then passes through the carbonized gas transfer pipeline 22, the first four-way cross pipe 23, and the re-combustion pipeline 48, flows into the second carbonized gas burner 45, and is supplied into the re-combustion chamber 3d. The carbonized gas supplied into the re-combustion chamber 3d, which contains dioxins, is re-combusted at a temperature of 800 degrees Celsius or higher (carbonized gas re-combustion process), and is then released into the atmosphere from the exhaust pipe 43 and the upper end of the main duct 27.

[0030] Then, when the temperature inside the combustion chamber 25 reaches 800 degrees Celsius or higher as measured by the first thermocouple (other temperature measuring means) 28 due to the operation of the combustion burner 32, the operation of the re-combustion burner 44, which had been operating up to that point, is stopped, the first switching valve, which had been open up to that point, is closed, and the second switching valve, which had been closed up to that point, is opened (flow path switching process). If the opening / closing damper 27c had been closed up to that point, this opening / closing damper 27c is opened. As a result, the carbonization gas generated in the first and second carbonization boxes 16 and 17 passes through the carbonization gas transfer pipeline 22, the first four-way cross pipe 23, the connecting pipe 51, and the second four-way cross pipe 33, and is supplied to the first carbonization gas burner 31 and used as fuel to heat the heating chamber 15. The gas inside the carbonization furnace 1 is then released into the atmosphere from the upper end of the main duct 27.

[0031] Therefore, according to the carbonization furnace 1 and the heat treatment method for the workpiece using this carbonization furnace 1 described above, it is possible to effectively prevent the release of carbonization gas containing dioxins into the atmosphere, which is generated when the temperature inside the combustion chamber 25 has not yet reached 800 degrees Celsius, that is, shortly after the start of operation of the carbonization furnace 1. [Explanation of symbols]

[0032] 1. Carbonization furnace 3. Re-combustion reactor 3D Re-combustion Chamber 15 Heating chamber 16. First carbonization box 17. Second carbonization box 22. Carbonization gas transfer pipeline 25 Combustion chamber 28. First thermocouple (other temperature measuring means) 31. First carbonization gas burner 32 Combustion burners 41. Second thermocouple (temperature measuring means) 44 Re-combustion burner 43 Exhaust pipe 45. Second carbonization gas burner 47. First valve-integrated tube 48. Re-combustion pipeline 50 Second valve built-in tube

Claims

1. A heating chamber whose interior is heated, a carbonization box placed inside the heating chamber and containing a material to be processed that includes organic matter, a combustion chamber located adjacent to the heating chamber, a combustion burner for heating the combustion chamber, and a carbonization gas burner located near the combustion burner and fueled by the carbonization gas generated when the material to be processed is heated. A re-combustion furnace with an internal re-combustion chamber, a re-combustion burner for heating the inside of the re-combustion chamber, a temperature measuring means for measuring the internal temperature of the re-combustion chamber, and an exhaust pipe for releasing the gas burned in the re-combustion chamber into the atmosphere. An industrial furnace characterized by comprising: a combustion burner that is started to operate after the temperature inside the re-combustion chamber, as measured by the temperature measuring means, reaches 800 degrees Celsius or higher due to the operation of the re-combustion burner, and a re-combustion pipeline that supplies the carbonization gas generated in the carbonization box into the re-combustion chamber.

2. A carbonization gas pipeline is connected to the middle of the aforementioned re-combustion pipeline to supply the carbonization gas to the carbonization gas burner. The industrial furnace according to claim 1, characterized in that a switching valve is provided in the middle of the above-mentioned re-combustion pipeline or the above-mentioned carbonization gas pipeline to switch the supply destination of the carbonization gas to either the re-combustion chamber or the carbonization gas burner.

3. Other temperature measuring means are provided in the combustion chamber. The industrial furnace according to claim 2, characterized in that the switching valve is switched so that the carbonization gas is supplied to the carbonization gas burner after the temperature inside the combustion chamber, as measured by the other temperature measuring means, reaches 800 degrees Celsius or higher.

4. A method for heat treatment of a workpiece using an industrial furnace comprising: a heating chamber whose interior is heated; a carbonization box placed inside the heating chamber and containing a workpiece containing organic matter; a combustion chamber located adjacent to the heating chamber; a combustion burner for heating the combustion chamber; a carbonization gas burner located near the combustion burner and fueled by carbonization gas generated when the workpiece is heated; a re-combustion furnace whose interior is a re-combustion chamber; a re-combustion burner for heating the re-combustion chamber; a temperature measuring means for measuring the internal temperature of the re-combustion chamber; an exhaust pipe for releasing the gas burned in the re-combustion chamber into the atmosphere; and a re-combustion pipeline for supplying carbonization gas generated in the carbonization box into the re-combustion chamber, wherein A re-combustion chamber heating step in which the re-combustion chamber is heated by the re-combustion burner described above, A combustion chamber heating step is performed in which, after the temperature inside the re-combustion chamber measured by the above temperature measuring means reaches 800 degrees Celsius or higher, the heating chamber is heated by the above combustion burner. This combustion chamber heating process involves supplying the carbonized gas generated in the carbonization box to the re-combustion chamber via the re-combustion pipeline in a carbonized gas re-combustion process, A method for heat-treating an object to be treated using an industrial furnace, characterized by comprising the following:

5. Other temperature measuring means are provided in the combustion chamber. After the temperature inside the combustion chamber, as measured by the other temperature measuring means, reaches 800 degrees Celsius or higher, the carbonization gas re-combustion process is stopped. A flow path switching process that exclusively supplies the carbonization gas generated in the carbonization box to the carbonization gas burner, A method for heat treatment of an object to be treated using an industrial furnace according to claim 4, characterized by comprising the above.

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