JP2004183989A - Waste disposal method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste disposal method and its device for giving efficient incinerating treatment to wastes while minimizing the release of dioxines. <P>SOLUTION: A granular or grainy microwave absorptive heating medium 41 and the wastes 40 are stored in a drum body 10 which can be rotationally driven around a horizontal or oblique axis, and they are stirred and mixed with the rotation of the drum body 10. In this state, the mixture is irradiated with microwaves emitted from a magnetron 21 to cause the temperature rise and resulting combustion of the waste with the heat of the wastes 40 themselves and conductive heat from the microwave absorptive heating medium 41. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waste disposal method and an apparatus for incinerating waste such as used disposable diapers.
[0002]
[Prior art]
2. Description of the Related Art Various technologies for incinerating household waste such as garbage and used disposable diapers using microwaves have been proposed. In addition, in the method of irradiating microwaves only to the waste, it is difficult to raise the temperature of the waste, whose dielectric constant is not so large, to the combustion temperature. A technology has also been proposed in which an absorption heating element (high-temperature heating element) is attached to the bottom of an incinerator (housing), and the waste (heated object) is heated and incinerated by contact with the high-temperature microwave absorption heating element. (For example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-4-98787
[Problems to be solved by the invention]
However, according to the technology described in Patent Document 1, when a certain amount of waste is piled up in an incinerator and irradiated with microwaves, the material is rapidly heated because it is in contact with the microwave absorbing heating element. The temperature of the waste in the middle and upper layers is increased only by the heat generated by the waste itself. For this reason, there is a problem that it takes a long time until all of the input waste is burned out and the treatment efficiency is low. In addition, since the temperature rise is not rapid and the temperature of the waste is in the temperature range of 300 to 400 ° C., which is considered to be the generation temperature of dioxins, the plastic containing chlorine in the waste has a long time. If mixed, the exhaust gas may contain highly toxic dioxins.
[0005]
The present invention has been made in view of the above problems, and a waste disposal method capable of efficiently incinerating waste and suppressing release of dioxins as much as possible. It is another object of the present invention to provide a waste treatment apparatus used for implementing the treatment method.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a waste treatment method according to the present invention is characterized in that a mixture of a granular or granular microwave-absorbing heating element and waste is irradiated with microwaves to generate heat and microwave absorption of the waste itself. It is characterized in that the waste is heated and burned by conduction heat from the heating element.
[0007]
Further, a granular or granular microwave-absorbing heating element and waste are accommodated inside a drum body that is driven to rotate about a horizontal or inclined axis, and the mixture is stirred and mixed by rotating the drum body. The method is characterized by irradiating microwaves to raise the temperature of the waste by the heat generated by the waste itself and the conduction heat from the microwave absorbing and heating element, and to burn the waste.
[0008]
In addition, the waste treatment apparatus according to the present invention includes a hermetically sealable casing, a rotatable support that is rotatable about a horizontal or inclined axis in the casing, and a granular or granular microwave-absorbing heating element and waste. A drum body that can be accommodated, a driving unit that rotationally drives the drum body, and a microwave irradiation unit that can irradiate a microwave to a mixture of the microwave absorbing heating element and the waste that are stirred and mixed inside the rotating drum body. And a microwave generator attached to the casing.
[0009]
The “microwave absorbing heating element” used in the present invention is not particularly limited. However, it is difficult to transmit the irradiated microwave and efficiently absorbs the irradiated microwave, so that the waste to be treated (the water contained in the waste is It is desirable that the material has a property of generating heat at a higher heat generation efficiency than that of (excluding). That is, for example, a material having a large dielectric constant has a high microwave absorptivity and a high heat generation efficiency. Therefore, a microwave absorption heating element made of one or a plurality of such materials may be appropriately selected and used.
Specifically, for example, metal oxides or carbides containing zinc, copper, manganese, cobalt, iron or the like as a main component, or ceramics containing carbon powder, alumina, silicon carbide, zirconia or the like as a main component Such a known microwave absorption heating element can be used.
In addition, when the heating element is disposable (discarded together with the burned and incinerated waste), it is particularly preferable to use an inexpensive material, for example, carbon (graphite) together with an appropriate heat-resistant binder (for example, clay). A solid obtained by molding and drying can also be used as a microwave absorbing heating element.
[0010]
However, in any case, in the present invention, since the waste and the microwave-absorbing heating element are mixed and heated, the microwave-absorbing heating element is used in the form of granules or granules. Here, the particle size of the microwave-absorbing heating element is not particularly limited, but if the particle size is too small, it becomes difficult to handle, and if the particle size is too large, the surface area per unit mass (specific surface area) of the heating element is small. As a result, the microwave absorption efficiency is deteriorated, and the contact area with the waste is reduced, so that the heat transfer efficiency from the heating element to the waste is also reduced, and the waste treatment efficiency tends to be reduced. Therefore, the particle size of the microwave absorbing heat generating element is preferably about 0.1 to 30 mm, and is particularly preferably granulated or 1 to 10 mm in particle size.
[0011]
Further, the shape of the granules or the particles of the microwave absorbing heating element having the above-mentioned particle diameter is not particularly limited. Granules or granules can be used.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0013]
[Embodiment 1]
The above-mentioned granular or granular microwave-absorbing heating element and waste to be treated are previously mixed in an appropriate ratio, and this mixture is converted into a microwave-shielding casing (container, incinerator, or the like). Container) and irradiate with microwaves.
Then, the waste and the microwave-absorbing heating element that make up the mixture each generate and raise the temperature, but the rate of temperature rise is faster with the microwave-absorbing heating element, so the waste is generated by the waste itself. In addition to the above, heating and temperature rise are also caused by conduction heat from the microwave-absorbing heating element that has become hotter.
At this time, unlike the technique described in Patent Document 1, the microwave absorbing heating element is in uniform contact with all the wastes in the mixed state, so that the wastes are quickly heated to the combustion temperature to improve the efficiency. Good incineration becomes possible. Further, since the temperature rises quickly and the waste passes through the temperature range of 300 to 400 ° C. in a short time, generation and release of dioxins can be suppressed as much as possible.
[0014]
[Embodiment 2]
According to the treatment method described in the first embodiment, it is possible to perform waste incineration more efficiently than in the technique of Patent Document 1, but for example, a microwave absorbing heating element is placed under the waste. In such a case, the irradiated microwave passes through the waste and is absorbed by the microwave-absorbing heating element, so that the rate of temperature rise of the microwave-absorbing heating element may be reduced. This is because microwaves are attenuated when passing through waste.
Therefore, in order to further increase the processing efficiency, a processing method in which the microwave absorbing heat generating element and the waste are accommodated in a rotating drum body while stirring and mixing, and a microwave is irradiated onto the mixing body is considered.
[0015]
First, an example of a waste treatment apparatus used for carrying out such a treatment method will be described with reference to FIGS.
A waste treatment apparatus generally indicated by reference numeral 1 in FIG. 1 includes a sealable casing 2 made of a material having a microwave shielding property such as a metal. The casing 2 includes a cylindrical casing main body 3 and a pair of front and rear disc-shaped lids 4 and 5 for sealing both ends of the casing main body 3. The casing main body 3 is supported on a base 7 via a gantry 6 in a posture in which its axis is inclined. The lids 4 and 5 are detachably fixed to flange portions formed at both ends of the casing main body 3 using a plurality of sets of bolts 8 and nuts 9.
[0016]
Inside the casing 2, there are provided a cylindrical drum body 10 made of a heat-resistant metal or the like, and a plurality of support rollers 11 for supporting the drum body 10. The drum body 10 is rotated around the inclined axis by the respective supporting rollers 11 that are in rolling contact with the outer peripheral surface of the drum body 10 in a state where the drum body 10 is inclined so that the axial direction thereof is substantially parallel to the axial direction of the casing body 3. Supported as possible.
[0017]
A circular opening 12 is formed on the inclined upper end side of the drum body 10. On the other hand, the inclined lower end side of the drum body 10 is closed by a bottom wall portion 13, and a drive shaft 14 parallel to the axial direction of the drum body 10 is fixed at the center of the bottom wall portion 13. The drive shaft 14 protrudes out of the casing 2 through a hole formed in the lid 5, and a pulley 15 is fixed to the protruding portion. A motor 16 (drive means) is provided on the base 7, and an annular transmission belt 18 is bridged between a pulley 17 fixed to an output shaft of the motor 16 and a pulley 15 on the drive shaft 14 side. Thus, the drum body 10 can be rotationally driven by the driving force of the motor 16 (the rotation direction is counterclockwise when viewed from the upper end side of the drum body 10). The rotation speed of the drum body 10 is not particularly limited, but may be, for example, a low speed rotation of about one rotation per minute.
On the inner peripheral surface of the drum body 10, a plurality of plate-like stirring blades 19 inclined with respect to the axial direction of the drum body 10 are provided so as to protrude in the radial direction and the axial direction. Reference numeral 20 denotes a mechanical seal provided to prevent gas and / or microwave from leaking from between the hole formed in the lid 5 and the drive shaft 14 and to secure the hermeticity of the casing 2. Is shown.
[0018]
A magnetron 21 (microwave generator) is attached to the lid 4 of the casing 2. The magnetron 21 is a known magnet used for a microwave oven or the like, and is fixed to a mounting seat 22 formed integrally with the lid 4 as shown in FIG. Reference numeral 21a indicates an output section of the magnetron 21 that emits microwaves. A tip portion of the output portion 21a protrudes inward of the casing 2 from an inner surface of the lid 4, and a cylindrical cover portion 23 that covers the output portion 21a is formed integrally with the mounting seat 22. The tip of the cover 23 is sealed with a partition plate 24 made of a microwave-permeable material (for example, quartz glass). The partition plate 24 is sandwiched between a flange portion formed at the tip of the cover portion 23 and an annular pressing member 25, and is fixed by bolts and nuts 26.
[0019]
The magnetron 21 is provided in a state inclined with respect to the plate surface of the lid 4. This is because the microwave radiated from the magnetron 21 (output unit 21a) is directed toward the mixture of the microwave absorbing heating element and the waste that are stirred and mixed in the drum body 10, as indicated by the arrow in FIG. This is for the purpose of irradiation.
[0020]
Further, as shown in FIG. 1, an air supply port 28 is formed at a lower portion of the casing body 3 and an exhaust port 29 is formed at an upper portion thereof. An air supply pipe 30 is connected to the air supply port 28, and air supply means 31 such as a fan or an air pump is provided at a tip of the air supply pipe 30, and an open / close valve 32 is provided in the middle of the air supply pipe 30. I have. On the other hand, an exhaust pipe 34 having an on-off valve 33 in the middle thereof is connected to the exhaust port 29, and the end of the exhaust pipe 34 is connected to exhaust gas purifying means 35. The exhaust gas purifying means 35 in this embodiment includes a chamber 36 and a burner 37, and burns fuel such as propane gas supplied from a fuel supply source (not shown) to the burner 37 in the chamber 37, thereby forming an exhaust pipe 34. A method of secondary combustion of the exhaust gas from the fuel at a high temperature is employed. Reference numeral 38 denotes a discharge pipe for discharging purified exhaust gas to the atmosphere.
[0021]
Further, although not shown, the waste treatment apparatus 1 is provided with a pressure sensor for detecting the pressure in the casing 2, a control means for controlling the operation of the magnetron 21 in accordance with the detection value of the pressure sensor, and the like. .
[0022]
Next, a waste disposal method performed using the above-described waste disposal apparatus 1 will be described.
First, the nut 9 is loosened, the lid 4 is removed from the casing body 3 together with the magnetron 21, and the waste 40 such as a used disposable diaper and the microwave absorbing and heating element 41 are put into and housed in the drum 10 through the opening 12. I do. In addition, as the microwave absorption heating element 41, a granular or granular thing as described in the above-mentioned [Means for Solving the Problems] is used. The waste 40 and the microwave-absorbing heating element 41 are charged at an appropriate ratio (mass ratio) according to the flammability of the waste to be treated, the dielectric constant of the microwave-absorbing heating element to be used, and the like.
[0023]
After the lid 4 is attached as before and the casing 2 is closed by closing both the on-off valves 32 and 33, the rotation of the drum 10 is started by the motor 16, and at the same time, the microwave is generated by the magnetron 21. Start irradiation.
Then, as the drum 10 rotates, the waste 40 and the microwave absorbing and heating element 41 are stirred and mixed. That is, the waste 40 and the microwave-absorbing heating element 41 scraped in the circumferential direction by the stirring blade 19 are dropped slightly forward (toward the opening 12) because the stirring blade 19 is inclined, and the drum body While repeating the operation of rolling backward (toward the bottom wall portion 13) along the inclination of the inner peripheral surface of the inner peripheral surface 10 and being raked up by the stirring blade 19 again, the mixture is uniformly mixed. The mixture thus stirred and mixed is irradiated with microwaves emitted from the output portion 21a of the magnetron 21 and transmitted through the partition plate 24, so that the waste 40 and the microwave absorbing and heating element 41 each generate heat.
[0024]
Here, when the pressure in the casing 2 rises due to the water vapor evaporated from the waste 40 and the thermally expanded air, the control unit turns on and off the power supply to the magnetron 21 based on the detection value of the pressure sensor. Then, control is performed to maintain the pressure in the casing 2 at a predetermined pressure (for example, about 0.2 MPa in gauge pressure). By performing microwave heating in such a “steamed” state for a predetermined time (for example, about 30 minutes), the waste 40 is sterilized. (If the waste does not require sterilization, this sterilization step can be omitted.)
[0025]
Next, while continuing to rotate the drum body 10 and irradiate the microwave, the burner 37 is ignited and the on-off valve 33 on the exhaust pipe 34 side is opened. As a result, the gas containing water vapor filled in the casing 2 flows into the chamber 36 as exhaust gas and is exposed to a high temperature due to the flame from the burner 37, thereby causing harmful effects such as carbon monoxide and nitrogen oxide. The components are further oxidized and made harmless, and bacteria that have not been killed in the sterilization step are also sterilized, and the purified exhaust gas is released from the discharge pipe 38 into the atmosphere. By opening the on-off valve 33, the pressure in the casing 2 becomes substantially equal to the atmospheric pressure.
[0026]
Since the irradiation of the microwave from the magnetron 21 is continued thereafter, the temperature of the waste 40 and the microwave absorber 41 starts to rise rapidly from the time when the moisture is completely evaporated from the waste 40. Here, the rate of temperature rise is higher in the microwave absorbing and heating element 41, so that the waste 40 is heated and raised not only by its own heat generation but also by the conduction heat from the higher temperature microwave absorbing and heating element 41. Let it warm.
When the temperature of the waste 40 exceeds the spontaneous ignition temperature, the on-off valve 32 on the air supply pipe 30 side is opened and the operation of the air supply means 31 is started, and outside air is sent into the casing 2 from the air inlet 28. Then, the waste 40 starts burning (thermal decomposition) by a reaction with oxygen contained in the sent outside air. After the start of combustion, the rotation of the drum body 10 and the irradiation of microwaves are continued, in principle, so that the temperature of the waste 40 (and the microwave absorbing heat generating body 41) is reduced to at least about 800 to 900 ° C. to generate dioxin. The combustion (incineration) of the waste 40 is advanced while maintaining the temperature in a temperature range that does not occur.
[0027]
When the combustion is completed and the waste 40 is incinerated, the rotation drive of the drum body 10 and the irradiation of the microwave are stopped, and the operation of the air supply means 31 and the fuel supply to the burner 37 are also stopped. Then, the lid 4 is opened after the inside of the casing 2 has cooled to some extent, and the mixture of the ash (incineration residue) of the waste 40 remaining inside the drum body 10 and the microwave-absorbing heating element 41 is taken out. . In addition, the taken-out microwave absorption heating element 41 may be discarded together with the ash, or may be separated from the ash and reused.
[0028]
As described above, in this embodiment, the granular or granular microwave-absorbing heating element 41 and the waste 40 are housed inside the drum body 10 that is driven to rotate about the inclined axis, and the drum body Since the mixture is irradiated with microwaves while being stirred and mixed by the rotation of 10, the microwaves do not pass through the waste 40, and the microwaves are directly irradiated and absorbed by the microwave-absorbing heating element 41, so that the rate of microwave irradiation increases. The temperature rising speed of the wave absorbing heating element 41 is improved. Further, the microwave-absorbing heating element 41 that has become high temperature uniformly contacts the waste 40, and the heat transfer efficiency from the microwave-absorbing heating element 41 to the waste 40 becomes extremely good. Therefore, even if the waste 40 is not so large in dielectric constant, the waste heat 40 can be very quickly heated to the combustion temperature by the heat of conduction from the microwave absorbing and heating element 41 and incinerated. Processing can be performed even more efficiently.
In addition, while passing through a temperature range of 300 to 400 ° C., which is the generation temperature of dioxins, in a short time and continuing microwave irradiation during combustion, the combustion temperature can be maintained at a high temperature. Even when chlorine-containing plastics or the like are mixed in the waste 40, the generation of dioxins and their release into the atmosphere can be suppressed as much as possible.
Further, by performing a sterilization step of irradiating microwaves in a state where the casing 2 is sealed and keeping the waste 40 in a steamed state for a predetermined time, bacteria or the like attached to or contained in the waste 40 are released to the atmosphere. It is possible to prevent the surrounding environment from being polluted.
[0029]
It is needless to say that the processing method and the processing apparatus of the present invention are not limited by the above embodiments. For example, in the above-described case, the inside of the opening 12 on one end side of the drum body 10 was irradiated with microwaves. A configuration in which a large number of holes having an appropriate opening diameter are formed in a porous shape or a mesh shape in which a number of holes are formed, and microwaves are transmitted through the peripheral wall to irradiate the internal waste and the microwave absorbing heating element. It is also possible.
Further, in the above, the casing 2 and the drum body 10 are formed in a cylindrical shape. However, these shapes are arbitrary, and for example, a box-shaped casing may be adopted. Any shape such as a cylindrical shape can be adopted.
[0030]
Further, in the above, the drum body 10 is supported in a state where its axis is inclined. However, the drum body may be supported with its axial direction being horizontal, and the supporting method is not limited to the one by the support roller 11 and is optional. It is. Similarly, the transmission mechanism for transmitting the rotation of the motor 16 (drive means) to the drum body is not limited to the one using a pulley and a transmission belt, and for example, a transmission mechanism using gears may be employed. Of course, a power source (for example, an engine) other than the motor may be employed as the driving means.
Further, in the above, the waste and the microwave-absorbing heating element are accommodated from the opening formed by removing the lid 4, but if the lid can be closed so that the gas and the microwave in the casing do not leak out, the opening may be opened. The arrangement position and the shape of are arbitrary.
[0031]
Further, in the above description, air is injected into the casing 2 by the air supply means 31 during combustion. However, by providing exhaust means such as a suction pump on the exhaust port 29 side to reduce the pressure in the casing, the air is supplied from the air supply port. A configuration in which outside air is sucked into the casing may be adopted. It is also conceivable to supply oxygen from the oxygen cylinder into the casing in order to promote the combustion of the waste.
Furthermore, in the above, the afterburner-type exhaust gas purifying means 35 is provided. It is also conceivable to employ exhaust gas purifying means configured to purify the exhaust gas.
[0032]
【The invention's effect】
As described above, according to the present invention, waste having a relatively low dielectric constant can be promptly heated to the combustion temperature and efficiently incinerated, and the emission of dioxins can be reduced as much as possible. It is also possible to suppress it.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a configuration of a waste disposal apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing a configuration near a magnetron.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Waste treatment apparatus 2 Casing 10 Drum body 16 Motor (drive means)
21 magnetron (microwave generator)
40 Waste 41 Microwave absorption heating element

Claims (3)

Irradiating a microwave to a mixture of granular or granular microwave absorbing heat generating material and waste, and raising the temperature of the waste by the heat generated by the waste itself and the conduction heat from the microwave absorbing heat generating material and burning the waste; Waste treatment method characterized by the above-mentioned. A granular or granular microwave-absorbing heating element and waste are accommodated inside a drum body that is driven to rotate about a horizontal or inclined axis, and the mixture is stirred and mixed by the rotation of the drum body. Irradiating the waste with heat of the waste itself and conduction heat from the microwave-absorbing heating element to heat and burn the waste. A sealable casing, a drum body rotatably supported inside the casing so as to be rotatable about a horizontal or inclined axis, and capable of containing a granular or granular microwave-absorbing heating element and waste, and rotating the drum body Driving means for driving, and a microwave generator attached to a casing so as to be able to irradiate a microwave toward a mixture of a microwave absorbing heating element and waste which are stirred and mixed inside the rotating drum body. A waste treatment device comprising:

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