JP2005164097A - Melting furnace device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily remove molten slag deposited on a discharge passage and dust deposited on an exhaust gas passage. <P>SOLUTION: This melting furnace device 1 comprises a flame burner 25 provided at one end of a rotary furnace 3, a charge port 11 provided at the other end of the rotary furnace 3, through which ash is charged, the exhaust gas passage 59 connected to the other end for guiding exhaust gas into a secondary combustion furnace 61, and a closable on-off valve 63 provided in the exhaust gas passage 59. The discharge passage 51 is provided at one end for discharging return exhaust gas and the molten slag from the rotary furnace 3, and a second exhaust gas passage 67 is connected to the discharge passage 51 for guiding the exhaust gas from the exhaust gas passage 59 to the secondary combustion furnace 61. Because the on-off valve 63 is closed during operation, the exhaust gas is guided from one end to the discharge passage 51 and the second exhaust gas passage 67. A temperature in the discharge passage 51 becomes almost the same as that in the rotary furnace 3, and so the molten slag, if deposited on the discharge passage 51, is melted by the exhaust gas. When the combustion temperature of the flame burner 25 is lowered and the on-off valve 63 is opened, the exhaust gas is guided to the exhaust gas passage 59 having less resistance for clean-up in the duct of the second exhaust gas passage 67 to easily remove the dust. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a melting furnace apparatus for melting incineration ash etc. of municipal waste to make harmless slag, and more specifically, slag adhering to a discharge path for discharging molten slag from a rotary furnace, and exhaust gas for discharging exhaust gas The present invention relates to a melting furnace apparatus for easily removing dust adhering to a passage or improving the cooling effect of a heat exchanger connected to an exhaust gas passage of a secondary combustion furnace.

Conventionally, garbage disposal such as household waste and industrial waste has become a big social problem in terms of disposal site, but the same problem arises in the disposal of incinerated ash remaining after incineration. The applicants have developed an ash melting treatment method as a conventional technique. This is because the incinerated ash charged into the furnace is melted by combustion of an oxygen burner using a slowly rotating horizontal rotary furnace, the exhaust gas is detoxified via a slaked lime device and released into the atmosphere, and the molten slag is discharged from the outlet. It is made to flow down to the outside and transported as harmless granulated slag (for example, see Patent Document 1).
Japanese Patent No. 31153838

  By the way, conventionally, when the molten slag in the horizontal rotary furnace flows down from the discharge port and falls, the slag is cooled and adheres to the lower side wall, and this slag grows greatly. Therefore, there is a problem that it is necessary to melt and remove the adhered slag using an auxiliary burner.

  A conventional oxygen burner is supplied with kerosene and high-concentration oxygen and burns. When high-concentration oxygen is supplied, the temperature rises, but there is a problem that the combustion temperature cannot be controlled only by this high-concentration oxygen.

  In addition, the exhaust gas from the horizontal rotary furnace contains substances such as mercury and lead with a light boiling point, and these substances adhere as dust to the inner wall of the exhaust gas path from which the exhaust gas is discharged. It is necessary to clean the inside of the exhaust gas passage from time to time. For this purpose, since the dust is removed after the operation of the horizontal rotary furnace is stopped and the horizontal rotary furnace is cooled, there is a problem that much labor is required. Moreover, since the horizontal rotary furnace is made of bricks, it takes a long time to crack if it is not gradually cooled, and conversely, when raising the temperature of the horizontal rotary furnace for the same reason. It needs to be gradually raised and requires 24 to 30 hours before and after the dust removal cleaning. Accordingly, there is a problem that the ash melting processing capacity is lowered.

  Further, in the conventional heat exchanger, since the exhaust gas is cooled with water, the humidity in the exhaust gas increases, so that there is a problem that dust is easily attached to the inner wall of the heat exchanger and the amount of exhaust gas increases.

  The present invention has been made to solve the above-described problems.

The melting furnace apparatus of the present invention comprises a flame burner on one end side of the rotary furnace, and a melting furnace apparatus comprising an inlet for charging ash on the other end side of the rotary furnace,
An exhaust gas path for guiding exhaust gas to the secondary combustion furnace is connected to the other end side, and an open / close valve that can freely open and close the exhaust gas path is provided.
A discharge path for discharging the exhaust gas and the molten slag from the rotary furnace is provided on the one end side, and a second exhaust gas path for connecting the exhaust gas from the exhaust gas path to the secondary combustion furnace is connected to the discharge path. It is characterized by.

  In the melting furnace apparatus according to the present invention, in the melting furnace apparatus, the flame burner includes five fluids including fuel for generating combustion gas, compressed air, oxygen, combustion air, and cooling water for cooling the burner body. A burner is preferred.

The melting furnace apparatus of the present invention comprises a flame burner on one end side of the rotary furnace, and a melting furnace apparatus comprising an inlet for charging ash on the other end side of the rotary furnace,
An exhaust gas path for guiding exhaust gas to the secondary combustion furnace is connected to the other end side, and an open / close valve that can freely open and close the exhaust gas path is provided.
A discharge path for discharging exhaust gas and molten slag from the rotary furnace is provided on the one end side, and a second exhaust gas path for connecting the exhaust gas to the secondary combustion furnace is connected to the discharge path,
A second heat exchanger is connected to the first heat exchanger connected to the exhaust gas path of the secondary combustion furnace, and a mixture of air and water is contained in the exhaust gas in the second heat exchanger. It is the structure which cools exhaust gas by injecting.

  In the melting furnace apparatus according to the present invention, preferably, the mixture of air and water is controlled so as to appropriately maintain the inlet temperature of the bag filter.

  In the melting furnace apparatus according to the present invention, in the melting furnace apparatus, the first and second heat exchangers are radiation type double cylinders (inner cylinders) that have been examined for preventing dust from adhering to the external cooling fluid. And an outer cylinder type) are preferably provided in the heat exchanger.

  As will be understood from the means for solving the above problems, according to the present invention, the on-off valve provided in the exhaust gas passage is closed during normal operation, so that the high temperature return exhaust gas from the rotary furnace is temporarily reduced. Since it is led from the side through the discharge passage to the second exhaust gas passage, the slag is prevented from being attached to the inner wall of the molten slag tapping water. Also, since the exhaust path is maintained at almost the same temperature as that in the rotary furnace by the high temperature exhaust gas, when the molten slag falls on the exhaust path, the molten slag does not adhere to the side wall of the exhaust path or even adheres However, since the high-temperature exhaust gas passes, the slag melts and falls. Therefore, it is possible to prevent the occurrence of slag adhesion on the inner wall of the hot water and the discharge passage with a simple mechanism.

  Also, when removing dust adhering to the inner wall of the exhaust gas passage, the combustion temperature is lowered by squeezing the fuel of the flame burner and then the on-off valve is opened to change the flow of the exhaust gas passage. Adhesion is easily cleaned and dust can be easily removed. Accordingly, the dust in the exhaust gas passage can be removed by a simple mechanism without stopping the operation of the rotary furnace, so that the continuous operation of the rotary furnace can be improved and the ash melting processing capacity can be greatly improved.

  In addition, since the oxygen burner is configured to be supplied with five fluids, fuel, compressed air, oxygen, combustion air, and cooling water, it can be controlled to an appropriate temperature so as to obtain high-density thermal energy. As a result, stable melting treatment can be performed on a mixture of incineration ash and incineration fly ash having a variation in moisture content. Accordingly, the amount of exhaust gas can be further reduced, the exhaust gas treatment facility can be reduced in size, and the thermal efficiency can be increased. In addition, reusable molten slag that satisfies the elution standard can be generated by homogenizing and stirring the heat storage in the furnace accompanying the rotation of the rotary furnace. Dioxins can be decomposed by high-temperature combustion, and their generation can be controlled.

  In addition, since the mixture of air and water is sprayed into the exhaust gas in the second heat exchanger in a mist form, an efficient exhaust gas cooling effect can be obtained with a small amount of water. Moreover, if the amount of the above mixture increases, the amount of exhaust gas increases. If the amount of the mixture decreases, the cooling effect decreases, but the amount of the mixture is controlled so that the inlet temperature of the bag filter is properly maintained. Therefore, the amount of exhaust gas can be reduced and an efficient cooling effect can be obtained.

  Further, since the exhaust gas inside the first heat exchanger is not cooled with water as in the prior art, the humidity in the exhaust gas does not increase. The structure of the second heat exchanger is the same as that of the first heat exchanger, so that dust adhering to the inner wall can be reduced and the amount of exhaust gas can be greatly reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIGS. 1 and 2, FIG. 1 shows a processing flow by the melting furnace apparatus 1 according to this embodiment. The melting furnace apparatus 1 generally has an outer diameter of 2 m, an inner diameter of 1 m, and a total length of 4 m. The cylindrical horizontal rotary furnace 3 is provided. The horizontal rotary furnace 3 is supported by a support portion 9 attached to a base 7 by two annular convex portions 5, and is configured to rotate once, for example, every 3 minutes. Further, on the left side in FIG. 1, for example, an opening portion 11 is provided as an input port for raw material charging whose outer inner diameter is slightly smaller, and this opening portion 11 is covered with a left hood 13. Also, a large-diameter internal cavity 15 is formed at the center, and the right side in FIG. 1 is a small-diameter opening 17 only on the inner diameter and is covered with a right hood 19.

  In addition, the horizontal rotary furnace 3 is configured to be capable of rotating while avoiding communication with the atmosphere by providing a seal member in a small gap with respect to both hoods 13 and 19 attached to the base 7. .

  The raw material charging machine 21 penetrating the left hood 13 mixes the raw material to be melted (mainly ash) such as incineration ash, fly ash, and crushing residue and receives it into the hopper 23, and passes through the opening 11 to the internal cavity. 15

  For example, an oxygen burner 25 as a flame burner penetrating the right hood 19 keeps the inside at a high temperature of 1350 to 1400 ° C. by combustion (primary combustion) by supplying, for example, kerosene 27 and liquefied oxygen 29 as fuel, The raw material in the internal cavity 15 is melted.

  Referring also to FIG. 3, the oxygen burner 25 will be described in detail. The oxygen burner 25 includes kerosene 27 as fuel, high-concentration oxygen 29 supplied from a liquefied oxygen tank, compressed air 31, and combustion air. 33 is supplied by being controlled by the fuel supply unit 35. In the oxygen burner 25, kerosene 27 is mixed with compressed air 31 and atomized, and then burned with high-concentration oxygen 29. Furthermore, mixing of the combustion air 33 controls the amount of combustion heat and supplies the required thermal energy to the horizontal rotary furnace 3.

  As the combustion air 33, as shown in FIG. 1, the first heat exchanger 37 and the second heat exchanger 39, which are radiant heat exchangers which will be described in detail later, are used. 1 A part of hot air blown and heat-exchanged to cool the heat exchanger 37 is used and supplied.

  Further, the burner body 41 of the oxygen burner 25 is configured to be cooled by the cooling water 43. For example, the cooling chamber 45 is provided outside the intermediate wall of the burner body 41, and the cooling water 43 is supplied from one side and drained from the other side to cool the burner body 41 in the cooling chamber 45. .

  As described above, the oxygen burner 25 of this embodiment is configured to be supplied with five fluids of kerosene 27, compressed air 31, oxygen 29 (high concentration oxygen), combustion air 33, and cooling water 43. That is, as combustion conditions, the supply amount of kerosene 27 and the oxygen amount (high concentration oxygen 29) with respect to this kerosene supply amount are the main factors, and when high concentration oxygen 29 is supplied, the temperature rises. 29 alone cannot control the temperature. Further, when a proper amount of primary air (combustion air 33) is supplied, the heat capacity of the combustion gas increases, and conversely, when the primary air 33 is throttled, the temperature can be lowered. Therefore, since the inside of the right hood 19 (exhaust hood) can be easily controlled and maintained at an appropriate temperature, the molten slag can be smoothly discharged.

  Further, by rotating the horizontal rotary furnace 3, as shown in FIG. 2, the flame from the oxygen burner 25 and the high-temperature radiant heat accumulated in the horizontal rotary furnace 3 are turned into the raw material that is the object to be melted. Further, the raw material is melted by utilizing the stirring action by the rotation of the horizontal rotary furnace 3. This molten material is separated into harmful gas and harmless slag body when moving on the furnace inner wall rotating surface functioning as a fluid stalker.

  As shown in FIG. 2, the molten harmless slag body is, for example, a downward extension 51 (as a discharge path for discharging the molten slag from a slag discharge port 49 provided in a part of the peripheral wall 47 of the opening 17. It passes below the surface of the slag water tank 53 through the lower part of the right hood 19 and is transported by the granulated slag conveyor 55 and appropriately processed. The volume reduction rate with respect to the raw material of this slag is 1 / 2-1 / 3.

  Here, when the actions and effects of the horizontal rotary furnace 3 equipped with the oxygen burner 25 are summarized, high-density thermal energy can be obtained by combustion of the oxygen burner 25 that can be controlled to an appropriate temperature, so that the moisture content varies. Stable melting treatment is possible for a mixture of incinerated ash and incinerated fly ash. Moreover, the reusable molten slag satisfying the elution standard can be generated by homogenizing and stirring the heat storage in the furnace accompanying the rotation of the horizontal rotary furnace 3. Furthermore, the generation of dioxins by high temperature combustion can be controlled. Further, the combustion by the oxygen burner 25 can further reduce the amount of exhaust gas, reduce the size of the exhaust gas treatment facility, and increase the thermal efficiency.

  Further, as one of the features of this embodiment, the upper portion of the left hood 13 is communicated from the first exhaust outlet 57 to the secondary combustion furnace 61 through, for example, a first exhaust duct 59 as an exhaust passage, For example, a damper 63 is provided as an on-off valve for opening and closing the first exhaust gas duct 59 in the vicinity immediately above the one exhaust outlet 57. Further, in the middle of the lower extension 51 at the lower part of the right hood 19, the first exhaust gas is passed from the second exhaust outlet 65 through a second exhaust duct 67 as a second exhaust gas path, for example, at a position above the damper 63. It communicates with a duct 59. Note that the damper 63 is closed during a normal melting process by the horizontal rotary furnace 3.

  With the above configuration, the damper 63 is closed, so that the exhaust gas containing harmful gas in the horizontal rotary furnace 3 generated by the combustion of the oxygen burner 25 is on the right side in FIGS. 1 and 2, that is, the dotted line in FIG. As shown by the arrows, the second exhaust gas duct 67 and the first exhaust gas duct 59 pass from the second exhaust outlet 65 through the downward extension 51 of the right hood 19 from the opening 17 so as to return to the oxygen burner 25 side. To the secondary combustion furnace 61, and is sucked by a suction fan 73 through a detoxification device such as a first heat exchanger 37, a second heat exchanger 39, a bag filter 69, a catalyst 71, etc., and an exhaust pipe 75 ( Released from the chimney) to the atmosphere.

  At this time, since the damper 63 is closed, the high-temperature return exhaust gas at 1350 to 1400 ° C. from the horizontal rotary furnace 3 passes through the opening 17 and the right hood 19, so It is possible to prevent slag from attaching to the inner wall of the outlet 49. Further, since the inner wall of the right hood 19 is maintained at substantially the same temperature by the high-temperature exhaust gas, the degree of cooling is suppressed even when the molten slag tapping falls within the lower extension 51, and the side wall of the lower extension 51 Even if slag does not adhere to the lower extension 51, even if slag adheres to the side wall of the lower extension 51, the hot return exhaust gas passes through the lower extension 51, so that the slag melts and falls downward. As a result, it is possible to prevent the occurrence of slag adhesion in the downward extension 51, which has conventionally occurred, with a simple mechanism.

  In addition, since the exhaust gas contains substances such as mercury and lead having a low boiling point, dust adheres to the inner wall of the second exhaust gas duct 67, or molten fly ash enters the second exhaust gas duct 67. As a result, the pressure loss increases and the operating performance is reduced. In addition, the mixed ash of wet ash and incineration fly ash causes the second exhaust gas duct 67 to be clogged with dust due to the solidification phenomenon. In order to prevent this, it is sometimes necessary to perform a cleaning operation for removing the dust.

  Therefore, when the damper 63 is opened after the temperature of the oxygen burner 25 is reduced to about 1000 ° C. by reducing the fuel of the oxygen burner 25 in order to perform dust removal cleaning work, the exhaust gas at about 1000 ° C. has a low resistance. 1 Passes through the exhaust gas duct 59. As described above, the dust in the second exhaust gas duct 67 can be removed without stopping the operation of the horizontal rotary furnace 3 by the simple mechanism, so that the continuous operability of the horizontal rotary furnace 3 is improved and the incineration ash melting capacity is improved. Is greatly improved.

  Incidentally, in the prior art, the operation of the horizontal rotary furnace 3 is stopped in order to occasionally perform the operation of scraping and removing the molten fly ash inside the second exhaust gas duct 67. In order to stop the horizontal rotary furnace 3, since the horizontal rotary furnace 3 is made of brick, the brick will be cracked unless the temperature is gradually lowered over about 30 hours. In addition, in order to start the operation of the horizontal rotary furnace 3 after cleaning, it takes about 24 hours to reach a temperature of 1400 ° C. for the same reason. Therefore, the melting process could not be performed during this period.

  With reference to FIG. 1 again, a normal melting processing operation by the melting furnace apparatus 1 of this embodiment will be described. The exhaust gas sent to the secondary combustion furnace 61 is subjected to secondary combustion at a temperature of 800 to 880 ° C. in the secondary combustion furnace 61 by a kerosene burner 77 provided in the upper part of the secondary combustion furnace 61. The secondary-burned exhaust gas is cooled by a first heat exchanger 37 and a second heat exchanger 39, which are radiant heat exchangers, from a secondary combustion furnace 61 through an exhaust gas passage 79.

  The periphery of the first heat exchanger 37 is covered with a cooling chamber 81, and for example, air as a cooling fluid is supplied from the combustion air fan 83 to the cooling chamber 81 to cool the outer wall of the first heat exchanger 37. Is done. Further, the first heat exchanger 37 has a double-layered double cylinder (radiation-type structure that examines dust adhesion prevention) consisting of an inner cylinder and an outer cylinder that communicate with the cooling chamber 81 and through which air passes. Is provided, and when the exhaust gas passes through the inside of the first heat exchanger 37, heat is efficiently exchanged by the double cylinder. A part of the hot air whose temperature has risen in the cooling chamber 81 and the double cylinder is sent to the fuel supply unit 35 through the combustion air duct 85 and used as the combustion air 33, and the remaining hot air is used. Is discharged from the exhaust cylinder 75 into the atmosphere.

  The second heat exchanger 39 has substantially the same configuration as the first heat exchanger 37, and the periphery of the second heat exchanger 39 is also covered with a cooling chamber 87. For example, air as a cooling fluid is supplied from the air fan 89 to cool the outer wall of the second heat exchanger 39. Furthermore, a double cylinder that communicates with the cooling chamber 87 and through which air passes is provided inside the second heat exchanger 39, and when the exhaust gas passes through the inside of the second heat exchanger 39, It is a structure in which heat is exchanged efficiently with a heavy cylinder. Further, the warm air whose temperature has risen in the cooling chamber 87 and the double cylinder is discharged to the atmosphere through the pipe 91.

  Further, the second heat exchanger 39 is configured such that a mixture 93 of air and water is injected into the inside from an injection nozzle 95 provided at the upper part of the second heat exchanger 39. For example, the exhaust gas passage 97 for sending the exhaust gas from the second heat exchanger 39 to the bag filter 69 is provided with a temperature sensor 99 for detecting the exhaust gas temperature in the exhaust gas passage 97 on the inlet side of the bag filter 69. The detected detection signal is sent to, for example, the controller 101 as a control device. The controller 101 has a configuration in which the air and water mixture 93 is controlled to be supplied to an appropriate amount by a diaphragm provided in the controller 101 so that the temperature of the temperature sensor 99 becomes 200 to 210 ° C., for example.

  With the above configuration, the first heat exchanger 37 and the second heat exchanger 39 cool the exhaust gas with the air passing through the double cylinder, and are not cooled with water as in the prior art. Will not increase significantly. As a result, the amount of dust adhering to the inner walls of the first heat exchanger 37 and the second heat exchanger 39 and the periphery of the double cylinder is less than that in the prior art, and the amount of exhaust gas is greatly reduced.

  By the way, if the exhaust gas in the heat exchanger is cooled with water as in the past, the humidity in the exhaust gas increases, so dust is easily attached to the inner wall of the heat exchanger, and the amount of exhaust gas also increases. Since the air volume had to be increased, a large facility was required.

  Further, in addition to the cooling by the double cylinder, the air and water mixture 93 is sprayed in the second heat exchanger 39 in the form of a mist, so that the exhaust gas can be efficiently cooled with a small amount of water. If the amount of the mixture 93 increases, the amount of exhaust gas increases, and if the amount of the mixture 93 is small, the cooling effect decreases. In this embodiment, the amount of the mixture 93 decreases. It is controlled by the controller 101 and properly maintained, and the amount of exhaust gas is reduced to obtain a highly efficient cooling effect.

  In the first heat exchanger 37, the temperature of the exhaust gas is cooled to about 430 to 530 ° C, and in the second heat exchanger 39, the temperature of the exhaust gas is cooled to about 230 to 270 ° C.

  From the above, in this embodiment, when the exhaust gas passes through the catalyst 71, for example, dioxin becomes 0.01 ppm, and in the exhaust cylinder 75 (chimney), the exhaust gas temperature becomes a harmless gas of about 160 to 180 ° C. To be released.

  In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change.

It is a system diagram which shows the process flow which fuse | melts raw materials, such as incineration ash, and makes them harmless using the melting furnace apparatus of embodiment of this invention. FIG. 2 is a schematic explanatory cross-sectional view in which the vicinity of the horizontal rotary furnace of FIG. 1 is enlarged. It is an expanded sectional view of the oxygen burner of an embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melting furnace apparatus 3 Horizontal rotary furnace 7 Base 9 Support part 11 Opening part (input port)
13 Left hood 17 Opening 19 Right hood 21 Raw material charging machine 25 Oxygen burner (flame burner)
27 Kerosene (fuel)
29 Oxygen (high concentration oxygen)
31 Compressed air 33 Combustion air (primary air)
35 Fuel supply unit 37 1st heat exchanger 39 2nd heat exchanger 43 Cooling water 45 Cooling chamber 49 Slag discharge port 51 Downward extension part (discharge path)
57 First exhaust outlet 59 First exhaust duct (exhaust passage)
61 Secondary combustion furnace 63 Damper (open / close valve)
65 Second exhaust outlet 67 Second exhaust duct (second exhaust passage)
69 Bag filter 75 Exhaust pipe (chimney)
77 Kerosene burner 81 Cooling chamber 83 Combustion air fan 85 Combustion air duct 87 Cooling chamber 89 Cooling air fan 91 Pipe 93 Mixture 95 Injection nozzle 97 Exhaust gas path 99 Temperature sensor 101 Controller (control device)

Claims (5)

In the melting furnace apparatus comprising a flame burner on one end side of the rotary furnace, and an inlet for charging ash on the other end side of the rotary furnace,
An exhaust gas path for guiding exhaust gas to the secondary combustion furnace is connected to the other end side, and an open / close valve that can freely open and close the exhaust gas path is provided.
A discharge path for discharging the exhaust gas and the molten slag from the rotary furnace is provided on the one end side, and a second exhaust gas path for connecting the exhaust gas from the exhaust gas path to the secondary combustion furnace is connected to the discharge path. A melting furnace apparatus.   The melt according to claim 1, wherein the flame burner is a five-fluid burner comprising fuel for generating combustion gas, compressed air, oxygen, combustion air, and cooling water for cooling the burner body. Furnace equipment. In the melting furnace apparatus comprising a flame burner on one end side of the rotary furnace, and an inlet for charging ash on the other end side of the rotary furnace,
An exhaust gas path for guiding exhaust gas to the secondary combustion furnace is connected to the other end side, and an open / close valve that can freely open and close the exhaust gas path is provided.
A discharge path for discharging exhaust gas and molten slag from the rotary furnace is provided on the one end side, and a second exhaust gas path for connecting the exhaust gas to the secondary combustion furnace is connected to the discharge path,
A second heat exchanger is connected to the first heat exchanger connected to the exhaust gas path of the secondary combustion furnace, and a mixture of air and water is contained in the exhaust gas in the second heat exchanger. A melting furnace apparatus characterized by being configured to inject and cool exhaust gas.   4. The melting furnace apparatus according to claim 3, wherein the mixture of air and water is configured to be controlled so as to appropriately maintain the inlet temperature of the bag filter. The first and second heat exchangers have a configuration in which a double cylinder of a radiation type structure that examines dust adhesion prevention that allows a cooling fluid from the outside to pass therethrough is provided inside the heat exchanger. The melting furnace apparatus according to claim 3 or 4.

Images