JP2012125666A - Device for treating metal scrap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform temperature control of a rotary heating furnace by heating and circulating exhaust gas in the rotary heating furnace and by re-supplying it into the furnace.SOLUTION: The device for treating metal scrap comprises: a raw material supply device including a shredder for metal scrap (raw material) and a supply feeder; a rotary heating furnace which performs heat treatment by feeding the raw material from a supply path at one end and by rotating it in a cylindrical rotating body and discharges it from the other end, and which includes a heating device heating the cylindrical rotating body by electromagnetic induction heating and a circulation air supply pipe for introducing circulating high-temperature air into the cylindrical rotating body; a discharge tube provided at the other end, recovering the treated raw material, and discharging combustion gas; a dust collector removing impurity solid matter from the combustion gas and supplying it as exhaust gas to a secondary combustion furnace; the secondary combustion furnace thermally decomposing the exhaust gas at a high temperature and discharging it as the high-temperature air; a cooling tower adjusting the high-temperature air to a predetermined temperature; and a circulation fan circulating the high-temperature air to the circulation air supply pipe of the rotary heating furnace and resupplying it.

Description

  In this invention, scrap metal such as used aluminum cans is heat-treated in a rotary drum-type furnace, and unnecessary inflammables such as resin coatings and printed coatings attached to the surface of the scrap metal are incinerated and removed. It relates to processing equipment for making available resources, and in particular, it uses an electromagnetic induction heating type heating device for external heating of the rotary heating furnace and reuses the exhaust gas of the rotary heating furnace. is there.

  Conventionally, aluminum cans and the like have been frequently used as beverage containers. And from the viewpoint of resource reuse, a system has been built in which used aluminum cans are collected and recycled as raw materials for aluminum products. Similarly, recycling systems have been established for other metals.

  As an example of such recycling, taking aluminum cans as an example, the recovered aluminum cans are pulverized with a crusher or shredder, the iron pieces are recovered with a magnetic separator, and the surface is removed with a delacquer device or the like. A recycling process is comprised from the process of removing the residual resin film and printed coating film, the process of granulating the processed aluminum piece, the process of dissolving, and the like.

  The applicant has proposed a heat treatment apparatus as disclosed in Patent Document 1 as a delacquer apparatus in a process of removing a resin film or a printed film remaining on the surface of the recycling process.

JP 2009-287863 A

  In the delacquer apparatus described in Patent Document 1, an external heating apparatus of an electromagnetic induction heating type is used in order to compensate for the insufficient heat quantity and fluctuating heat quantity of the rotary heating furnace while using the combustion heat quantity of combustibles contained in the scrap material as a main heat source. Provided. However, when a heat treatment apparatus including this kind of electromagnetic induction heating type heating apparatus is actually operated, the internal temperature of the furnace (rotary kiln) can be raised only to about 450 ° C., depending on the specifications. It was confirmed. On the other hand, in order not to generate harmful substances such as dioxin during combustion, it is known that the furnace temperature is required to be around 600 ° C. Therefore, it is an object to provide means for raising the furnace temperature.

  In addition, scrap metal made by crushing used aluminum cans into a predetermined size is put into the rotary heating furnace through an appropriate supply device. Since it fluctuates, the temperature in the furnace constantly fluctuates due to fluctuations in the amount of heat generated during the combustion. For this reason, it is necessary to appropriately control the heating temperature by the electromagnetic induction heating type external heating device, but there remains a problem that temperature control by current control for electromagnetic induction heating is not always easy.

  The present invention has been invented to solve such a problem, and in order to increase the temperature in the rotary heating furnace, after heating the exhaust gas, it is circulated and re-supplied into the furnace. The purpose is to increase the temperature and control the temperature of the rotary furnace.

  In order to solve the above problems, the present invention provides a processing apparatus for metal scrap, a raw material supply apparatus including a crusher for crushing metal scrap, a supply feeder for conveying the crushed metal scrap, and one end. A rotary heating furnace in which metal scrap is charged from a provided supply path via the raw material supply device, heated while rotating in a cylindrical rotating body, and discharged from an outlet weir provided at the other end. A heating apparatus provided with a heating device for heating the rotating body by electromagnetic induction heating, a circulating air supply pipe for introducing circulating high-temperature air into the cylindrical rotating body, and a heat treatment provided at the other end of the rotating heating furnace The recovered metal scrap is recovered from the lower end, and a discharge cylinder that discharges the combustion gas generated in the rotary heating furnace, and the combustion gas discharged from the discharge cylinder is introduced to remove impure solids. In addition, a dust collector that supplies exhaust gas as a secondary combustion furnace, and a secondary combustion that exhausts the exhaust gas supplied from the dust collector, burns at a high temperature by a burner, and pyrolyzes to discharge as high-temperature air. A cooling tower that adjusts the high-temperature air discharged from the secondary combustion furnace to a predetermined temperature with humidified air, and the high-temperature air that is temperature-controlled in the cooling tower is circulated to a circulating air supply pipe of the rotary heating furnace And adopting a means of constituting with a circulation fan re-supplied to the rotary heating furnace.

  According to the apparatus of the present invention having such a configuration, the combustion gas discharged from the rotary heating furnace is collected and heated to be purified, and further adjusted to a temperature suitable for decomposing toxic substances. Will be resupplied.

  Further, the processing apparatus further includes a heat exchanger that lowers the temperature of a part of the high-temperature air discharged from the cooling tower by heat exchange with outside air and supplies the air as burner combustion air for the secondary combustion furnace. Adopted means.

  Thereby, a secondary combustion furnace can be burned more efficiently.

  In addition, a hot air shut-off damper and an outside air adjustment damper for introducing outside air are provided in the middle of the circulation path for circulating the high-temperature air discharged from the cooling tower, and the air re-supplied to the rotary heating furnace through the circulation fan is provided. The means of adjusting the temperature and the amount of oxygen was adopted.

  Moreover, the said dust collector employ | adopted the means that it was equipped with the cyclone separator.

  The temperature of the high-temperature air discharged from the secondary combustion furnace is about 800 ° C., and the temperature of the air introduced into the circulating air supply pipe of the rotary heating furnace via the circulation fan is about 600 ° C. It was adopted.

  By adopting such a temperature, in the secondary combustion furnace, it is possible to make the exhaust gas completely harmless, and in the rotary heating furnace, it is possible to achieve a temperature at which harmful substances can be reliably decomposed.

  An inlet double damper device including two rotary dampers interlocking with each other is provided between the raw material supply device and the supply path of the rotary heating furnace, and the two rotations interlocking with each other are provided at the lower end of the discharge tube. A means of providing an outlet double damper device composed of a damper was adopted.

  By providing a double damper device composed of two rotary dampers interlocking with each other at the inlet and outlet of the rotary heating furnace, it is possible to prevent wasteful combustion gas from being discharged from the rotary combustion furnace.

  The metal scrap processing apparatus of the present invention according to the above configuration is configured to adjust the combustion gas discharged from the rotary heating furnace to a temperature suitable for decomposing harmful substances by heating and purifying after collecting the dust. Since it is re-supplied to the rotary heating furnace, the combustion gas generated in the rotary heating furnace is completely pyrolyzed and rendered harmless, and circulates in the equipment, so that no harmful gas is discharged and the environment is discharged. Will not pollute.

  That is, since the rotary heating furnace can be burned at a high temperature of about 600 ° C., harmful substances such as dioxins generated when burning metal scrap can be reliably decomposed.

  In this case, since the air heated to a high temperature in the secondary combustion furnace is re-supplied, no additional energy is required to raise the temperature of the rotary heating furnace, so that a processing apparatus with high energy saving efficiency can be provided. .

  In addition, since high-temperature air having a stable temperature is supplied to the rotary heating furnace, it is possible to cope with a temperature change in the furnace due to the amount of metal scrap input, and to perform a stable treatment.

1 is a circuit diagram of an embodiment of a metal scrap processing apparatus according to the present invention. It is a simplified circuit diagram which shows the flow of intake / exhaust.

  Hereinafter, a preferred embodiment of a metal scrap processing apparatus according to the present invention will be described with reference to the accompanying drawings.

  In the circuit diagram of FIG. 1, reference numeral 1 denotes a rotary heating furnace, and heat treatment is performed while rotating a metal scrap material (raw material) introduced into the furnace from a supply path 1 a provided at one end thereof, thereby causing unnecessary combustibility of the surface. The product is discharged by incineration. The basic structure of the rotary heating furnace 1 is conventionally known, but in the present invention, electromagnetic induction heating type heating devices 1b and 1b are employed as the external heating device of the rotary heating furnace 1, and the rotary heating is performed. The cylindrical rotating body 1c of the furnace 1 is heated from the outside by heating by electromagnetic induction. Further, as will be described later, it has a circulating air supply pipe 1d for introducing circulating high-temperature air so that the raw material can be burned in a predetermined high-temperature atmosphere. 2 is a raw material supply device, which comprises a crusher 2a for crushing a raw material of a metal scrap material such as an aluminum can into a predetermined size, a supply feeder 2b including a conveyor device such as a belt conveyor or a screw device, The crushed raw material is charged into the rotary heating furnace 1 from the supply path 1a. Between this raw material supply device 2 and the supply path 1a of the rotary heating furnace 1, an inlet double damper device 3 comprising two rotary dampers interlocking with each other is provided to prevent wasteful discharge of internal combustion gas. is doing. That is, the inlet double damper device 3 is composed of, for example, two rotary dampers that are operated by an air cylinder, and is configured in conjunction with each other so that when one is open, the other is closed. The high-temperature combustion gas has a structure that does not leak outside.

  4 is a discharge tube provided at the other end of the rotary heating furnace 1, and drops and collects the heat-treated metal scrap material (product) discharged from the outlet weir 1e operated by the air cylinder, and rotates and heats it. The combustion gas generated in the furnace 1 is discharged as exhaust gas to the dust collector 6 described below. Reference numeral 5 denotes an outlet double damper device provided at the lower end of the discharge cylinder 4, which is composed of, for example, two rotary dampers that are operated by an air cylinder. When one is open, the other is closed so that the other is closed. In addition, the high temperature combustion gas in the furnace is not leaked to the outside when the scrap metal (product) after the treatment is recovered.

  6 is a dust collector, which introduces the exhaust gas discharged from the discharge cylinder 4, and removes impure solids such as dust with a cyclone separator 6a, for example, and passes the exhaust gas to the next secondary combustion furnace. Supply. The impure solids removed by the cyclone separator 6a are discharged and collected via the rotary valve 6b at the lower end.

  7 is a secondary combustion furnace, which sends LPG or the like to the burner 7a and burns the exhaust gas sent from the dust collector 6 at a higher temperature, thermally decomposes the gas to make it harmless, and turns it into hot air It is. The combustion temperature at this time is about 800 ° C. Burner combustion air is introduced into the secondary combustion furnace 7 from a heat exchanger 12 described later. The amount of air is controlled by a damper.

  8 is a cooling tower which adjusts the temperature of the high-temperature air discharged from the secondary combustion furnace 7 with humidified air. The air discharged from the cooling tower 8 is resupplied to the rotary heating furnace 1 through the circulation fan 9. The air temperature at this time is about 600 ° C. That is, the rotary heating furnace 1 is provided with a circulating air supply pipe 1d. The circulating high temperature air is introduced into the furnace, and the combustion temperature in the furnace is set to a temperature at which harmful substances such as dioxins are reliably decomposed. Raise to.

  The circulating fan 9 is supplied with the circulating air mixed with the outside air for supplying oxygen. The circulating air is provided with a hot air blocking damper 10 and the outside air is provided with an outside air adjusting damper 11 for rotation. The temperature of the air supplied to the heating furnace 1 and the amount of oxygen are adjusted.

  Reference numeral 12 denotes a heat exchanger. A part of the air discharged from the cooling tower 8 is subjected to heat exchange with the outside air by the heat exchanger 12 to lower the temperature, and is again returned to the secondary combustion furnace 7 for burner combustion air. Supply as. Some are also introduced into the dust collector 6 (see * 1).

  In the figure, T,... Are thermometers in each pipeline.

  As described above, in the metal scrap processing apparatus according to the present invention, the combustion gas generated in the rotary heating furnace 1 is first removed from the impure solids by the dust collector 6 and burned at a high temperature by the secondary combustion furnace 7. Then, it is further purified by thermal decomposition, and this high-temperature air is again introduced into the rotary heating furnace 1 so that the metal scrap material is burned in a high-temperature atmosphere. Therefore, the generated combustion gas is completely detoxified and circulates, so that not only there is no risk of polluting the environment, it is also possible to reduce the energy to burn the furnace at a high temperature, and a processing device with high energy saving efficiency Can provide.

  In the above configuration, the metal scrap material (raw material) charged into the rotary heating furnace 1 may be preliminarily washed or the like, but if the raw material contains too much water at this time, the rotary heating furnace 1 at the time of charging is used. There is a possibility that an adverse effect such as a crack in the heating furnace 1 may be caused by rapidly cooling the inside of the furnace. In particular, when the water content exceeds 10%, there is a concern about adverse effects. However, if the water content is about 2-3%, no problem occurs. Therefore, it is preferable to adjust the raw material charged into the rotary heating furnace 1 so that the water content is lowered by preheating the raw material.

  Next, an example of the temperature change of intake and exhaust in the processing apparatus will be described with reference to FIG. In this example, an example will be described in which raw material containing 6.5% of moisture and paint is charged by the raw material supply device 2 at 3210 kg per hour.

  First, the cylindrical rotating body of the rotary heating furnace 1 is externally heated by an electromagnetic induction heating type heating device having an output of 315 kw. At this time, the temperature of the kiln outlet air discharged from the discharge tube 4 was 318.4 ° C. This combustion gas is introduced into a dust collector 6 equipped with a cyclone separator and collects dust while being mixed with 291.6 ° C. humidified air sent from the heat exchanger 12. The temperature of the kiln exhaust discharged from the dust collector 6 is 318.4 ° C., and is introduced into the secondary combustion furnace 7 as it is. In the secondary combustion furnace 7, the exhaust gas is burned at a higher temperature and made harmless by thermal decomposition using LPG as fuel, but the temperature of the air in the secondary combustion furnace 7 has reached 800.0 ° C.

  The high-temperature air discharged from the secondary combustion furnace 7 is introduced into the cooling tower 8, adjusted and cooled by the humidified air, and then discharged from the cooling tower 8 and circulated to the rotary heating furnace 1. The temperature of the air is 634.6 ° C. This circulating air is mixed with outside air (circulating leak air) at 20.0 ° C. and then re-supplied to the rotary heating furnace 1 via the circulating fan 9. The temperature of the circulating mixed air at this time was 600.3 ° C. That is, the temperature of the air blown into the rotary heating furnace (kiln) 1 is about 600 ° C., and the combustion temperature in the furnace at this time is a temperature that can reliably decompose harmful substances such as dioxins.

  A part of the air discharged from the cooling tower 8 is introduced into the heat exchanger 12 as the secondary combustion furnace exhaust air at 634.6 ° C., and is cooled to 291.6 ° C. by the heat exchanger with the outside air. . A part of this air is introduced into the secondary incinerator 7 as burner combustion air, while a part of the air is sent to the dust collector 6 as humidified air.

  Thus, in the metal scrap processing apparatus according to the present invention, the combustion gas of the rotary heating furnace 1 is thermally decomposed and rendered harmless by the dust collector 6, the secondary combustion furnace 7, etc., and the temperature is adjusted. By re-supplying the rotary heating furnace 1 as kiln blowing air of about 600 ° C., the temperature inside the rotary heating furnace 1 can be set to an appropriate temperature that can decompose harmful substances.

DESCRIPTION OF SYMBOLS 1 Rotary heating furnace 1a Supply path 1b Electromagnetic induction heating type heating device 1c Cylindrical rotating body 1d Circulating air supply pipe 1e Outlet weir 2 Raw material supply device 2a Crusher 2b Supply feeder 3 Inlet double damper device 4 Outlet cylinder 5 Outlet double Damper device 6 Dust collector 6a Cyclone separator 7 Secondary combustion furnace 8 Cooling tower 9 Circulating fan 12 Heat exchanger

Claims (6)

A raw material supply device comprising a crusher for crushing metal scrap, and a supply feeder for conveying the crushed metal scrap,
A rotary heating furnace in which metal scrap is introduced from a supply path provided at one end through the raw material supply device, is heated while rotating in a cylindrical rotating body, and is discharged from an outlet weir provided at the other end. A rotary heating furnace comprising a heating device for heating the cylindrical rotating body by electromagnetic induction heating, and a circulating air supply pipe for introducing circulating high-temperature air into the cylindrical rotating body;
A discharge tube that is provided at the other end of the rotary heating furnace, drops and recovers the heat-treated metal scrap from the lower end, and discharges the combustion gas generated in the rotary heating furnace,
A dust collector for removing the impure solids by introducing the combustion gas discharged from the discharge cylinder, and supplying it to the next secondary combustion furnace as the exhaust gas;
A secondary combustion furnace in which the exhaust gas supplied from the dust collector is burned at a high temperature by a burner, pyrolyzed, and discharged as high-temperature air;
A cooling tower for adjusting the high-temperature air discharged from the secondary combustion furnace to a predetermined temperature with humidified air;
A circulating fan that circulates the high-temperature air whose temperature is adjusted in the cooling tower to the circulating air supply pipe of the rotary heating furnace and re-supply the rotary heating furnace;
A metal scrap processing apparatus comprising:   2. The metal scrap according to claim 1, further comprising a heat exchanger that lowers the temperature of a part of the high-temperature air discharged from the cooling tower by heat exchange with outside air and supplies the air as burner combustion air for the secondary combustion furnace. Processing equipment.   In the middle of the circulation path for circulating the high-temperature air discharged from the cooling tower, a hot air blocking damper and an outside air adjusting damper for introducing outside air are provided, and the temperature of the air re-supplied to the rotary heating furnace via the circulation fan; The metal scrap processing apparatus according to claim 1 or 2, wherein the amount of oxygen is adjusted.   The metal dust processing apparatus according to any one of claims 1 to 3, wherein the dust collector includes a cyclone separator.   The temperature of the high-temperature air discharged from the secondary combustion furnace is about 800 ° C, and the temperature of the air introduced into the circulating air supply pipe of the rotary heating furnace via the circulation fan is about 600 ° C. The metal scrap processing apparatus according to claim 4.   An inlet double damper device comprising two rotary dampers interlocking with each other is provided between the raw material supply device and the supply path of the rotary heating furnace, and two rotary dampers interlocking with each other are provided at the lower end of the discharge cylinder. The metal scrap processing apparatus according to any one of claims 1 to 5, further comprising an outlet double damper device.

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