JP5467594B2 - Rotary kiln - Google Patents

Description

  The present invention relates to a rotary kiln that is used for heat drying, incineration, or baking treatment of various materials, and more particularly to a rotary kiln that enables incineration or the like while maintaining the inside of the kiln in a reducing atmosphere.

  In recent years, for the purpose of effective use of resources, for example, waste printed boards are collected and processed to collect valuable metals such as gold, silver, copper, and platinum contained in the boards. The waste printed circuit board has printed wiring such as gold and copper on a base made of paper base or glass fiber base hardened with thermosetting phenolic resin or epoxy resin, as well as gold, silver, Many ICs and capacitors containing copper, platinum, and other valuable metals are attached. As a method for separating and recovering these various valuable metals, for example, dry distillation treatment is performed in a reducing atmosphere and a temperature atmosphere of 500 to 1000 ° C., and unnecessary resin components are removed by evaporation, while remaining residues There is a method in which the material is cooled to a temperature at which it is not rapidly oxidized even if it is contacted with the atmosphere, and the cooled product is pulverized and then separated into valuable metal and a base material component such as glass.

  When performing a dry distillation treatment as described above using a rotary kiln, especially when adopting a direct heating method in which the object to be treated is heated directly inside the kiln body, sliding between the rotating kiln body and the hood part is performed. Unless the surface is sealed and the outside air is not prevented from entering the kiln, the reducing atmosphere is not maintained, and the heat treatment of the workpiece cannot be performed stably.

  Therefore, as a sealing member of the sliding surface of the kiln main body of the rotary kiln, a member provided with a gland packing is generally used. However, in the cited document 1 (Japanese Patent Laid-Open No. 2001-324272), the gland packing is uneven wear. May cause problems with sealing performance and durability, and some sealing members are provided in multiple stages to increase the sealing surface distance to increase the sealing effect. There is a problem that maintenance work takes time, and a main seal part is formed by winding a seal part made of gland packing etc. around the kiln main body so as to be slidable, and a sheet-like outer part of the main seal part. Proposing a sealing structure in which a sealing material is sealed by elastically pressing a packing material against the outer peripheral surface of the kiln main body via an elastic body and surrounding it slidably.

  In Cited Document 2 (Japanese Patent Publication No. 59-53963), although the kiln body is an asphalt plant dryer that does not need to maintain a reducing atmosphere, a pressure sensor is provided inside the kiln, Excessive cooling air can be obtained by variably controlling the exhaust air volume of the exhaust fan based on the pressure sensor so as to keep the internal pressure constant, so that the amount of combustion gas sent into the kiln body is sucked and exhausted by the exhaust fan without excess or deficiency. A technique for preventing suction is described. In this type of asphalt plant dryer, as a sealing member for the sliding surface of the kiln body, for example, a metal seal plate with little wear is brought into contact with the outer peripheral surface of the dryer to suppress the intrusion of outside air.

JP 2001-324272 A Japanese Patent Publication No.59-53963

  However, if a seal member made of a gland packing or the like is used to seal the sliding surface between the kiln body and the hood as in the cited document 1, wear of the seal member is unavoidable, and the seal member should be replaced periodically. Is annoying. In addition, the method of preventing the intrusion of outside air by controlling the internal pressure in the kiln body to be constant as in the cited document 2 is preferable in terms of maintenance because there is no wear part, but combustion gas is generated from the sliding surface of the kiln body. In order to avoid leakage, the internal pressure in the kiln is set to be lower than the atmospheric pressure. Therefore, outside air is inevitably sucked from the gap between the seal plates, and it is difficult to make the kiln main body into a reducing atmosphere.

  This invention makes it a subject to provide the rotary kiln which is easy to maintain in view of said point, and can maintain the inside of a kiln main body stably in a reducing atmosphere.

  In order to solve the above-mentioned problems, in the rotary kiln according to claim 1 according to the present invention, both ends of a cylindrical kiln main body that is rotatably and tiltably supported are fitted to the hood, and the hood at one end is A rotary kiln having a burner for supplying hot air, an exhaust flue connected to the hood portion at the other end, and an exhaust fan for sucking and exhausting exhaust gas at the end of the exhaust flue, wherein the kiln is disposed in the hood portion An annular sealing material fixing piece is projected along the outer peripheral surface of the main body, and a sealing material that abuts against the sliding surface of the kiln main body and blocks the entry of outside air is attached to the tip of the sealing material fixing piece, A static pressure sensor that includes exhaust means for exhausting air in a gap space formed by the outer peripheral surface of the kiln main body, the sealing material fixing piece, and the sealing material with a predetermined suction force, and that detects a static pressure in the gap space; In the kiln body A static pressure sensor for detecting the static pressure of the exhaust means so that the static pressure value in the gap space detected by the static pressure sensor is maintained at a predetermined value lower than the static pressure value inside the kiln body. It is characterized by being configured to variably control the amount of exhaust air.

  Further, in the rotary kiln according to claim 2, the exhaust air amount of the exhaust fan is variably controlled based on the detection value of the static pressure sensor so that the static pressure value inside the kiln main body detected by the static pressure sensor becomes a predetermined pressure. It is characterized by being configured as described above.

  The rotary kiln according to claim 3 is characterized in that the gap between the outer peripheral surface of the kiln main body and the sealing material fixing piece has a labyrinth structure so that the flow rate of the outside air entering the gap space can be attenuated.

  The rotary kiln according to claim 4 is characterized in that the air exhausted from the gap space by the exhaust means is introduced into the exhaust flue downstream of the kiln main body.

  According to the rotary kiln according to claim 1 of the present invention, both ends of a cylindrical kiln main body that is rotatably and tiltably fitted are fitted to the hood, and the hood at one end is provided with a hot air supply burner. In addition, in the rotary kiln equipped with an exhaust flue connected to the hood portion at the other end and an exhaust fan for sucking and exhausting exhaust gas at the end of the exhaust flue, the hood portion extends along the outer peripheral surface of the kiln body. An annular sealing material fixing piece is projected, and a sealing material that abuts the sliding surface of the kiln main body and blocks the intrusion of outside air is attached to the tip of the sealing material fixing piece, and the outer peripheral surface of the kiln main body and the sealing material A static pressure sensor for detecting static pressure in the gap space, and a static pressure in the kiln main body, including exhaust means for discharging the air in the gap space formed by the fixed piece and the sealing material with a predetermined suction force Detecting static pressure cell Since the static pressure value in the gap space detected by the static pressure sensor is variably controlled so that the exhaust air amount of the exhaust means is maintained at a predetermined value lower than the static pressure value inside the kiln body, The outside air that enters the kiln body through the gap between the kiln body and the sealing material can be forcibly exhausted by the exhaust means to prevent entry into the kiln body, and the inside of the kiln body can be stably maintained in a reducing atmosphere. In addition, it is almost unnecessary to periodically replace the sealing material, and maintenance is easy.

  According to the rotary kiln according to claim 2, the amount of exhausted air from the exhaust fan is variable based on the detected value of the static pressure sensor so that the static pressure value detected by the static pressure sensor becomes a predetermined pressure. Because the static pressure value inside the kiln main body is set to be almost equal to the atmospheric pressure, the external air suction force into the kiln main body can be reduced as much as possible. The static pressure value of the gap space formed with the sealing material can also be set to a value slightly lower than the atmospheric pressure, and the forced exhaust amount and fluctuation amount by the exhaust means are small, which is preferable.

  Further, according to the rotary kiln according to claim 3, since the gap between the outer peripheral surface of the kiln body and the sealing material fixing piece has a labyrinth structure so as to be able to attenuate the flow velocity of the outside air entering the gap space, The amount of outside air that tends to enter the inside can be suppressed, and the inside of the kiln main body can be stably maintained in a reducing atmosphere more effectively.

  According to the rotary kiln of claim 4, since the air exhausted from the gap space by the exhaust means is introduced into the exhaust flue downstream of the kiln main body, the outside air and exhaust gas exhausted by the exhaust means are It can be processed at low cost using existing equipment.

It is a schematic explanatory drawing which shows one Example of the incineration facility provided with the rotary kiln which concerns on this invention. It is a partially cutaway enlarged view of the rotary kiln of FIG. FIG. 3 is an enlarged view of a main part of FIG. 2.

  The rotary kiln is fitted with the hood part at both ends of a cylindrical kiln body that is rotatably and tiltably supported. The hood part at one end is provided with a hot air supply burner and the hood part at the other end is exhausted. A flue is connected to the exhaust flue, and an exhaust fan for sucking and exhausting exhaust gas is provided at the end of the exhaust flue. An annular sealing material fixing piece projects from the hood portion along the outer peripheral surface of the kiln main body, and the tip of the sealing material fixing piece abuts against the sliding surface of the kiln main body to prevent the intrusion of outside air. A sealing material is installed.

  Further, an exhaust duct is connected to a gap space formed by the outer peripheral surface of the kiln main body, the sealing material fixing piece, and the sealing material, and the amount of exhaust air by the exhaust means provided downstream of the exhaust duct is adjusted by adjusting the opening of the damper. Variable control is possible, and a predetermined amount of air can be sucked and exhausted from the gap space. And a static pressure sensor for detecting the static pressure in the gap space and a static pressure sensor for detecting the static pressure inside the kiln main body, the static pressure value detected by both static pressure sensors is taken into the controller, and the static pressure The exhaust air amount of the exhaust means is maintained so that the static pressure value detected in the gap space detected by the sensor is maintained at a predetermined value lower than the static pressure value inside the kiln body, for example, a low value of about −10 to −20 mmAq. It is configured to be variably controlled.

  Further, the controller that captures the static pressure value inside the kiln body detected by the static pressure sensor compares the captured static pressure value with a preset static pressure set value, and based on the difference value amount, It is preferable to variably control the amount of exhausted air so that the static pressure value inside the kiln main body is always maintained at the set value. The static pressure setting value inside the kiln main body is preferably set so as to be substantially equal to the atmospheric pressure. The atmospheric pressure ratio is about −several mmAq to −several tens mmAq, and the combustion gas from the kiln main body to the outside is preferable. Is set to an appropriate value that can reduce the external air suction force into the kiln body as much as possible.

  The gap between the outer peripheral surface of the kiln main body and the sealing material fixing piece has a labyrinth structure so that the flow rate of outside air entering the gap space can be attenuated and the amount of intrusion can be suppressed. The air exhausted from the gap space is introduced into the exhaust flue downstream of the kiln main body, and the exhaust gas derived from the kiln main body is combined with the exhaust gas to perform dust collection processing etc. to simplify the device I am doing so.

  Then, when recovering valuable materials such as valuable metals by incinerating processed materials such as waste printed boards in the rotary kiln, the burner is operated with an appropriate combustion amount according to the supply amount of the processed materials. Then, waste printed circuit boards, which are processed products, are supplied to the kiln main body by a predetermined amount by a supply means such as a screw conveyor or pusher, and unnecessary temperatures such as unnecessary resin components in the printed circuit boards are burned and vaporized for removal. Then, incineration is performed while maintaining the valuable metal, which is a useful material that remains later, at about 550 ° C. so that it can be suitably recovered.

  At this time, the static pressure value in the gap formed by the outer peripheral surface of the kiln main body, the sealing material fixing piece, and the sealing material detected by the static pressure sensor and the static pressure value inside the kiln main body are sequentially taken into the controller. The controller variably controls the exhaust air flow rate so that the static pressure value in the gap space is kept lower than the static pressure value inside the kiln body, for example, about -10 to -20 mmAq. To do. As a result, the air in the gap space is guided to the exhaust flue downstream of the kiln main body through the exhaust duct, and the outside air entering from the gap of the sealing material that contacts the sliding surface of the kiln main body is also on the exhaust duct side. The outside air does not enter the kiln body. A part of the combustion gas in the kiln body is also sucked and exhausted through the exhaust duct.

  In addition, if the exhaust air amount of the exhaust fan is variably controlled so that the static pressure inside the kiln body is maintained at an atmospheric pressure ratio, for example, about −3 to −4 mmAq, there is no blowing of combustion gas from the kiln body to the outside, and The external air suction force into the kiln body can be reduced as much as possible, and the static pressure value in the gap space formed by the outer peripheral surface of the kiln body, the sealing material fixing piece, and the sealing material can be set slightly lower than the atmospheric pressure. The forced exhaust amount and fluctuation amount by the exhaust means are also preferably reduced. Further, if the gap between the outer peripheral surface of the kiln main body and the sealing material fixing piece has a labyrinth structure, the flow rate of the outside air entering the gap space can be attenuated and the amount of outside air entering the space can be suppressed.

  In this way, the outside air that enters the kiln from the gap between the kiln body and the sealing material is forcibly exhausted by the exhaust means to prevent entry into the kiln body, so the inside of the kiln body is reduced to a reducing atmosphere. Thus, the combustion temperature rises extremely due to the intrusion of outside air into the kiln body and greatly exceeds the set temperature of 550 ° C. It is possible to prevent glass fibers from melting and mixing and making it difficult to separate and recover, or the recovered valuable metals to oxidize, leading to a decrease in the recovery rate. Can be recovered efficiently and suitably.

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

  1 in the figure is an incineration facility that incinerates a processed material such as a waste printed circuit board at a predetermined temperature, and recovers valuable materials such as valuable metals from the residue remaining later. A rotary kiln 2 is provided that can incinerate a processed product such as a waste printed circuit board in a reducing atmosphere, and an outlet hood portion 3 is provided on the downstream side of the rotary kiln 2, and an exhaust flue is provided in the outlet hood portion 3. 4, the exhaust gas is sucked by the exhaust fan 5 interposed in the middle of the exhaust flue 4 to maintain the high-temperature gas flow passing through the kiln, and the combustible gas contained in the exhaust gas A secondary combustion furnace 6 that completely burns and decomposes unburned components and the like, a cooling tower 7 that rapidly cools the exhaust gas to prevent resynthesis of dioxins, and a dust collector 8 such as a bag filter are sequentially passed through a chimney 9 at the end. As a structure that releases to the atmosphere more That.

  The rotary kiln 2 supports a cylindrical kiln main body 10 on a machine base 11 so as to be rotatable and tilted at an appropriate angle (for example, about 2 degrees), and a drive device (not shown) and an inverter (not shown). )) At an appropriate speed. The kiln main body 10 is provided with a heat-resistant caster 13 such as refractory bricks or ceramics on the inner peripheral surface of a steel plate 12 formed in a cylindrical shape, and protects from high-temperature hot air supplied from a burner 15 described later. It is storing heat with.

  The end of the kiln main body 10 is provided with a hood portion. An inlet hood portion 14 on the supply side of a processed product R such as a waste printed circuit board is provided with a burner 15 for supplying hot air and a screw as a processed product supply means. While having the conveyor 16 and the supply hopper 17, the outlet hood portion 3 on the processed material discharge side has a discharge portion 18 for discharging the processed material R ′ mainly composed of valuable metals through incineration processing, and exhaust gas derivation. And an exhaust flue 4 for use. In addition, a heat-resistant caster 13 is attached to the inner peripheral surfaces of the inlet hood part 14 and the outlet hood part 3 in the same manner as the kiln body 10.

  The inlet hood portion 14 and the outlet hood portion 3 are provided with annular sealing material fixing pieces 19 and 20 projecting along the outer peripheral surface of the kiln body 10 fitted therein, and the sealing material fixing pieces. For example, a base end portion of a metal seal plate 21 is fixed to the tip portions of 19 and 20 as a sealing material for preventing the entry of outside air, and the free end portion of the seal plate 21 is used as an outer peripheral surface of the kiln body 10. The gap between the outer peripheral surface of the kiln body 10 and the inlet hood part 14 and the outlet hood part 3 is sealed without interfering with the rotation of the kiln body 10. I try to suppress the intrusion of outside air.

  The inlet hood portion 14 is provided with a static pressure sensor 22 for detecting the static pressure inside the kiln main body 10, and the static pressure value detected by the static pressure sensor 22 is taken in. A controller 24 for adjusting and controlling the opening degree of the air volume adjusting damper 23 provided downstream of the exhaust flue 4 based on the value is provided.

  The above control will be described in detail. The static pressure sensor 22 prevents the combustion gas G in the kiln from leaking out of the outer peripheral surface of the kiln main body 10 and the inlet hood 14 or the outside air A from being excessively sucked. While detecting the static pressure inside the kiln main body 10, the opening of the damper 23 is appropriately adjusted based on the detected value to adjust the suction force by the downstream exhaust fan 5, and the static pressure inside the kiln main body 10 is changed to atmospheric pressure. (Slight negative pressure is preferable, for example, about atmospheric pressure ratio is about −several mmAq to −several tens mmAq). The exhaust fan 5 may be controlled by an inverter, and the suction force may be controlled by controlling the rotational speed of the exhaust fan 5 in place of the opening of the damper 23 to adjust the static pressure inside the kiln body 10 as described above. .

  Further, in the substantially closed gap space 25 formed by the outer peripheral surface of the kiln body 10, the sealing material fixing piece 19 of the inlet hood portion 14, and the seal plate 21, a static pressure for detecting the static pressure inside the gap space 25 is detected. A pressure sensor 26 and exhaust means 27 for exhausting air A ′ in the gap space 25 with a predetermined suction force are provided.

  The exhaust means 27 has one end portion of the exhaust duct 28 connected to the gap space 25, and the other end portion connected to the exhaust flue 4 downstream of the outlet hood portion 3 and in the middle of the exhaust duct 28. Is provided with a damper 29 for adjusting the air volume, and the controller 24 takes in the static pressure value in the gap space 25 detected by the static pressure sensor 26, and takes in the static pressure value and the static pressure sensor 22. The suction force is adjusted by appropriately adjusting the opening of the damper 29 based on the static pressure value in the kiln. At this time, the static pressure in the gap space 25 is slightly lower than the atmospheric pressure, for example, a state slightly lower than the static pressure inside the kiln maintained at about −3 to −4 mmAq (for example, the static pressure ratio in the kiln). The air A ′ in the gap space 25 is forcibly exhausted and introduced into the downstream exhaust flue 4.

  By controlling as described above, the outside air A constantly enters the kiln body 10 where the static pressure is kept lower than the atmospheric pressure from the gap space 25 and the like, but the static air in the gap space 25 is constantly entering. Since the pressure is sucked slightly stronger by the exhaust duct 28 so as to be kept lower than the inside of the kiln main body 10, the outside air A entering the gap space 25 does not go to the inside of the kiln but from the exhaust duct 28. The air is forcibly exhausted, thereby preventing the outside air A from entering the kiln body 10 as much as possible, and the inside of the kiln body 10 can be stably maintained in a reducing atmosphere.

  Further, the gap between the outer peripheral surface of the kiln body 10 and the sealing material fixing piece 19 of the inlet hood portion 14 is shown in FIG. 3 so that the flow rate of the outside air A entering the gap space 25 can be sufficiently attenuated. As shown, the baffle plates 30 for external air collision are arranged in a zigzag pattern to form a labyrinth structure. In the gap between the outer peripheral surface of the kiln main body 10 and the sealing material fixing piece 20 of the outlet hood portion 3, the baffle plates 30 are similarly arranged in a staggered manner to form a labyrinth structure, so that excess outside air into the kiln main body 10 is formed. It tries to prevent A from entering as much as possible. In addition, according to the exhaust means 27, a part of the combustion gas G in the kiln main body 10 is also sucked and exhausted together with the outside air A that tends to enter the kiln main body 10, but these mixed air to be exhausted is exhausted. A ′ is introduced into the exhaust flue 4 downstream of the kiln and joined with the combustion gas G derived from the kiln main body 10 so that dust collection processing and the like can be performed together without requiring a separate dust collector or the like. Processing can be suitably performed while simplifying the apparatus.

  Then, in the incineration facility 1 having the rotary kiln 2, for example, when the processed material R such as a waste printed board is incinerated in a reducing atmosphere to recover the valuable material R ′ such as a valuable metal, first, the processed material R The burner 15 is operated at an appropriate combustion amount so that valuable metals can be recovered in a suitable state in accordance with the supply amount of the burner 15, and the static pressure inside the kiln main body 10 at that time is operated. The damper 23 opening is appropriately adjusted based on the value, and the static pressure in the kiln main body 10 is controlled to be maintained at a slightly negative pressure (for example, about −3 to −4 mmAq in terms of the atmospheric pressure ratio) from the atmospheric pressure.

  Moreover, the damper 29 opening degree of the exhaust duct 28 connected to the clearance space 25 between the outer peripheral surface of the kiln main body 10 and the sealing material fixing piece 19 of the inlet hood portion 14 is adjusted, and the static pressure in the clearance space 25 is adjusted. 10 is controlled to be slightly lower than the static pressure inside the kiln (for example, about -10 to -20 mmAq in the kiln static pressure ratio), and the ambient air A that is about to enter the kiln from the gap space 25 is flowed by the labyrinth structure. The air is forcedly exhausted from the exhaust duct 28 while suppressing the intrusion and the air inside the kiln body 10 is cut off as much as possible to maintain the reducing atmosphere.

  Then, in the above operation state, the processed material R such as the waste printed board in the supply hopper 17 is sequentially sent to the kiln main body 10 by the screw conveyor 16 and supplied. The treated material R supplied into the kiln main body 10 is exposed to hot air from the burner 15 in a reducing atmosphere while flowing down in the kiln, and is stably incinerated at a preset temperature of about 550 ° C. Unnecessary resin components and the like contained in the processed product R such as the printed circuit board are removed by combustion and vaporization, and the valuable material R ′ is discharged from the downstream discharge unit 18.

  As described above, in the rotary kiln 2, even when the air inside the kiln main body 10 is cut off as much as possible, that is, when it is required to perform incineration or the like in a reducing atmosphere, it will enter through the gap between the kiln main body and the hood. By forcibly exhausting the outside air, it is possible to prevent the outside air from entering the kiln as much as possible, thereby stably maintaining the inside of the kiln in a reducing atmosphere, and processing such as incineration in a suitable state. It becomes possible.

  In the present embodiment, the case where the treated product is incinerated while maintaining the inside of the kiln in a reducing atmosphere has been described. For example, even when the treated product is fired or heat-dried. By adopting the same configuration as that of the present embodiment, it is possible to prevent the entry of excess outside air into the kiln.

DESCRIPTION OF SYMBOLS 1 ... Incineration facility 2 ... Rotary kiln 3 ... Outlet hood part (hood part) 4 ... Exhaust flue 5 ... Fan exhaust 10 ... Kiln main body 14 ... Inlet hood part (hood part) 15 ... Burner 19, 20 ... Sealing material fixed piece 21 ... Seal plate (seal material)
DESCRIPTION OF SYMBOLS 22 ... Static pressure sensor 23 ... Damper 24 ... Controller 25 ... Crevice space 26 ... Static pressure sensor 27 ... Exhaust means 28 ... Exhaust duct (exhaust means) 29 ... Damper (exhaust means)
30 ... Baffle plate A ... Outside air G ... Combustion gas A '... Air in crevice space R ... Processed material R' ... Valuable material

Claims (4)

  Both ends of a cylindrical kiln main body that is tiltably supported so as to be rotatable are fitted to the hood, and a hood part at one end is provided with a burner for supplying hot air, and an exhaust flue is provided at the hood part at the other end. In the rotary kiln equipped with an exhaust fan that sucks and exhausts exhaust gas at the exhaust flue end, an annular sealing material fixing piece projects from the hood portion along the outer peripheral surface of the kiln body, and the sealing material A seal member that abuts the sliding surface of the kiln main body and blocks the intrusion of outside air is attached to the distal end portion of the fixed piece, and in the gap space formed by the outer peripheral surface of the kiln main body, the seal material fixed piece, and the seal material. An exhaust means for exhausting air with a predetermined suction force, a static pressure sensor for detecting a static pressure in the gap space, and a static pressure sensor for detecting a static pressure inside the kiln body are provided, and the static pressure sensor In the gap space Rotary kiln, characterized in that the value was constructed the exhaust air of the exhaust means so as to be maintained at a low predetermined value than the kiln body of the static pressure so as to variably control.   The exhaust air amount of the exhaust fan is variably controlled based on a detection value of the static pressure sensor so that a static pressure value inside the kiln main body detected by the static pressure sensor becomes a predetermined pressure. Item 10. A rotary kiln according to Item 1.   The rotary kiln according to claim 1 or 2, wherein a gap between the outer peripheral surface of the kiln main body and the sealing material fixing piece has a labyrinth structure so that the flow velocity of the outside air entering the gap space can be attenuated.   The rotary kiln according to claim 1, 2 or 3, wherein the air exhausted from the gap space by the exhaust means is introduced into an exhaust flue downstream of the kiln body.

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