JP3311466B2 - Detoxification equipment for refuse incineration dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detoxification apparatus for refuse incineration dust, that is, an apparatus for treating refuse discharged from a refuse incinerator into harmless substances free of heavy metals and dioxins. .

[0002]

BACKGROUND OF THE INVENTION Traditionally, incineration ash generated in incinerators and dust collected by dust collectors have been disposed of as landfills. According to the amendment of the Law, dusts containing a large amount of harmful heavy metals and dioxins cannot be subjected to landfills or other final disposal unless they have been subjected to the prescribed intermediate treatment specified by the Minister of Health and Welfare. I have. That is, they are melt solidification, cement solidification, chemical treatment, and treatment with a solvent such as an acid.

However, various problems have been pointed out in these processes in practical use. That is, in the process (1), dust is melted in a melting furnace at 1300 to 1400 ° C. and taken out as vitrified slag.
The consumption of fuel such as oil and gas is enormous, the processing cost is high, and operation management is extremely difficult. Is a process of granulating or molding by a cement solidification facility and curing and solidifying. However, mixing with cement increases the disposal capacity and has a problem in the stabilization of the process. Is a method in which dust is kneaded with a chemical to stabilize it chemically, but the chemical is expensive, the processing cost is high, and there is a problem in the stabilization of the processing. The treatment is to wash the dust with acid or other solvent and treat the eluate with heavy metals.
Since the treatment is a liquid treatment, the problem of acid discharge and the treatment of heavy metal sludge remain, the equipment becomes complicated, and the maintenance is complicated.

[0004] In addition, regarding the removal of dioxins contained in dust, the generation of dioxins inside the incinerator is suppressed by improving combustion, and the synthesis of dioxins outside the incinerator is controlled by temperature control according to national guidelines. Measures have been taken to enhance the dust collection processing of exhaust gas discharged from incinerators, purify exhaust gas by catalytic action, and remove dioxin by thermal decomposition of dust ash and the like.

However, is only a measure for reducing the amount of dioxin emission related to the incinerator main body, and taking such measures alone is not enough to remove dioxincins.
Alternatively, it is intended to decompose dioxins by heating the collected ash to about 350 to 400 ° C., which is a very effective countermeasure for dioxin. However, heavy metals in the ash can be removed. And its practical value as a facility effect is low.

[0006] Under such circumstances, there is a strong demand for the development of a method or apparatus for effectively eliminating heavy metals and dioxins in dust.

Therefore, the present inventor has conducted various experiments and studies in order to respond to such a demand. In order to effectively remove heavy metals and dioxins in the dust, the dust was reduced to about 1%.
It was concluded that heating at 000 ° C. was the best course.

[0008] That is, heavy metals such as Pb and Cd contained in dust are considered to exist as compounds such as chlorides and sulfides, and when they are heated, they volatilize to the gas side at a relatively low temperature. However, when a dust heating experiment was performed using an electric furnace, it was found that heating the dust at about 1000 ° C. was the most effective in volatilizing heavy metals. FIG. 5 is a graph showing the relationship between the heating time and the heavy metal volatilization rate when the dust is heated at 1000 ° C. in an electric furnace based on the measurement results in this experiment. In addition, it is understood that 95% or more is volatilized by heating for about 15 minutes.

[0009] Further, it has been found from this experiment that dioxins in the dust are almost completely decomposed. That is, before treatment, dioxins (PCDDs + P
CDFs) was present at 3900 ng / g, but when dust was volatilized at 1000 ° C., 99.89% was decomposed,
Only 2.4 ng / g remained in the dust after the treatment.

[0010] Further, the electric furnace in the crucible release state, soot
The dust was heated at 1000 ° C. for 15 minutes in the presence of air
Above, Cr of the treated ash⁶⁺When a dissolution test was performed, C
r⁶⁺Was 3 mg / l (the pH of the treated ash was
9.0). Also, under the same conditions, dust is removed from the air.
Low O shut off_TwoAfter heating in an atmosphere, the Cr of the treated ash
⁶⁺The dissolution test of⁶⁺Elution value is 0.0
(The pH of the treated ash was 10.5
). In addition, the latter treated ash is removed from the air and into the air.
When each was cooled below, in each case, Cr⁶⁺Elution
The value was less than 0.05 mg / l (pH of the cooled ash)
Is 9.2 for cooling in air, and
Total was 9.5). From these experimental results, it was found that Cr⁶⁺Is soot
Cr in dust ³⁺Although it exists stably as³⁺Is empty
By heating at high temperature in air ⁶⁺Oxidized to
This oxidation is effectively suppressed by shutting off air.
Ash that has been heat-treated with air shut off
As for, even if exposed to air during the cooling process,
³⁺Cr⁶⁺It has been found that the oxidation to is suppressed. You
That is, it is preferable that the heat treatment of the dust be performed in an enclosed space.
No.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made based on such knowledge, and is capable of effectively detoxifying refuse incineration dust, and has a simple facility and easy operation. It is an object of the present invention to provide a detoxification apparatus for refuse incineration dust that is advantageous from the point of view.

[0012]

The detoxification apparatus for refuse incineration dust according to the present invention, which has solved the above-mentioned problems, comprises a first furnace and a first furnace for sealing both ends of a cylindrical furnace body so as to be relatively rotatable. A two-lid body, a support mechanism for fixedly supporting the two lid bodies and rotatably supporting the furnace body in an inclined state, a driving mechanism for rotating and driving the furnace body in a certain direction, and a two-lid body penetrating through the furnace body And is connected to a rod-shaped electric heating element that heats and maintains the inside of the furnace at 1000 ° C. and a first lid that seals a high-side end of the furnace body, and supplies dust into the furnace body. A dust supply mechanism, a processing ash discharging mechanism for discharging the processing ash from the furnace body, and a processing ash discharging mechanism for discharging the processing ash from the furnace body, the processing ash discharging mechanism being connected to at least one of the lids. And an exhaust mechanism for discharging exhaust gas from the furnace body. In such an apparatus, it is preferable that the electric heating element is disposed in a furnace body area that does not directly come in contact with the dust, and it is preferable that the furnace body and both lids are made of a heat-resistant fire-resistant structure. Further, it is preferable that the inner peripheral surface of the furnace body is formed as an uneven surface in which a plurality of ridges or grooves extending over the entire width in the axial direction are arranged in parallel at predetermined intervals in the circumferential direction.

[0013]

The dust in the furnace is transferred while being mixed and stirred by the rotation of the furnace in a certain direction. Therefore, the dust is uniformly and efficiently heated to about 1000 ° C. by the radiant heat of the electric heater and the heat transfer from the peripheral portion of the furnace. As a result, the decomposition of diokincin contained in the dust and the volatilization of heavy metals are effectively performed. In addition, since the furnace body is sealed with a lid and the dust is heated in a low O ₂ atmosphere in which air is shut off, the change of Cr ³⁺ to Cr ⁶⁺ is favorably suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be specifically described below with reference to the embodiments shown in FIGS. In the following description, for convenience, front and rear mean left and right in FIG. 1 and left and right mean left and right in FIG. 2, respectively.

In the detoxifying apparatus of this embodiment,
As shown in FIG. 1, a cylindrical furnace body 1 is rotatably supported by a support mechanism 2 in a posture inclined downward and backward.

That is, the support mechanism 2 includes an inclined table 4 supported on the base (or installation floor) 3 in a downwardly inclined manner.
, And a plurality of support rollers 5 rotatably supported on the inclined table 4. The furnace body 1 is rolled and supported by a pair of front and rear annular guides 6, 6 fitted on the peripheral wall 1a thereof by rollers 5. It is rotatably supported (in a downwardly inclined position) at an angle that matches θ. Guides 6, 6
Have annular flanges 6 which can be engaged with the rollers 5.
a, 6a are formed, and are designed so that a thrust load in the axial direction of the furnace body 1 can be received. The inclined table 4 has a rear end portion pivotally supported on the base 3 so as to be vertically swingable, and a suitable vertical expander / contractor (for example, a screw type jack, interposed between the front end and the base 3). The tilt angle θ can be arbitrarily adjusted by expanding and contracting the hydraulic jacks 8). It should be noted that the residence time of the dust 40a in the furnace body 1 is about 15 minutes, as can be understood from the experimental results shown in FIG. Therefore, in this embodiment, the inclination angle θ of the inclined table 4, that is, the inclination angle of the furnace body 1 is
It is set so that a residence time of about 15 minutes is secured.

Further, the support mechanism 2 fixedly supports lids 9 and 10 that seal each end of the furnace body 1. That is, as shown in FIG. 1 and FIG.
The lids 9 and 10 are fixedly supported in a front-rear manner via brackets 9a and 10a. As shown in FIGS. 1 and 2, each of the lids 9 and 10 is a disk having peripheral walls 9 b and 10 b which are rotatably fitted to the end of the furnace body 1. An annular sealing material 11 provided on a peripheral portion,
11 seals the end of the furnace body 1 so as to be relatively rotatable.

The furnace body 1 and the lids 9 and 10 are both constituted by a heat-insulating fire-resistant structure in which a heat-insulating and heat-resistant fire-resistant material layer is formed on the inner surface of a steel plate casing. As the sealing material 11, a material having heat resistance, for example, a braided packing made of heat-resistant fiber is used. In particular, as shown in FIG. 3, the inner peripheral surface of the furnace body 1 has a plurality of ridges 1c (or concave grooves 1d) extending over the entire width in the axial direction and arranged in parallel at predetermined intervals in the circumferential direction. It is configured on the surface 1b, and is designed so that when the furnace body 1 is rotated, the dust 40a surely follows and moves with the movement of the inner peripheral surface 1b. In other words, an appropriate frictional force is applied between the dust 40a and the inner peripheral surface 1b of the furnace so that the dust 40a does not slip on the inner peripheral surface 1b of the furnace. Of course,
Since each ridge 1c (or groove 1d) extends in the axial direction, the axial movement of the dust 40a on the inner peripheral surface 1b is hindered by the presence of the ridge 1c (or groove 1d). Never. Although not shown, suitable lids 9 and 10 and the furnace body peripheral wall 1a are provided with appropriate viewing windows, and the second cover 10 is provided with a temperature detector for detecting the temperature inside the furnace body 1. Installed.

The rotatable and sealed furnace body 1
Is driven to rotate in a fixed direction by an appropriate drive mechanism 12. That is, this mechanism 12
As shown in the figure, a sprocket ring 13 is fitted to the furnace body peripheral wall 1a, and a speed reduction motor 14 is mounted on the inclined base 4, and the sprocket wheel 14a provided on the output shaft of the motor 14 and the sprocket ring 13 are connected to an endless chain. 15 to link the furnace body 1 to X
It is configured to be driven to rotate in the direction. Since the furnace 1 and the drive mechanism 12 are supported by the inclined table 4, even when the inclination angle θ of the inclined table 4 is changed, the driving system of the furnace 1 has no influence.

Further, both lids 9 and 10 are provided in FIG. 1 and FIG.
As shown in the figure, a plurality of rod-shaped electric heating elements 1 penetrating inside the furnace body 1
Are fixedly supported so that the inside of the furnace body 1 is heated and maintained at about 1000 ° C. Each of the electric heating elements 16 has a rod-shaped siliconite heating element 16b inserted and held in a ceramic protection pipe 16a. By making both ends of the protection pipe 16a penetrate and supported by both lids 9, 10, a furnace body is provided. It is fixed to the lids 9 and 10 in a state parallel to one axis. The power supply line 16c connected to the heating element 16b
Are guided from the end of the protective tube 16a to a power source outside the furnace body 1.

When the dust 40a is supplied into the furnace body 1, the dust 40a is stored in the lower part of the furnace body 1. When the furnace body 1 is rotated in the X direction from this state, the peripheral wall is Since the left half portion 1a (hereinafter referred to as “rising peripheral wall portion”) 1′a of 1a rises, the dust 40a is generated by the dust surface 40a in combination with the fact that the peripheral surface in the furnace is formed as the uneven surface 1b as described above. It will be raised with the rising peripheral wall portion 1'a (see FIG. 4A). However, when this dust 40a is raised to a position P slightly below the X direction (hereinafter, referred to as a “lifting position”) P immediately above the rotation center of the furnace body 1, the rising peripheral wall portion 1′a exerts the rising action. It cannot be received, and is naturally dropped from the lift release point P (see FIGS. 4B and 4C). That is, as shown in FIG. 4, the dust 40 a is driven by rotating the furnace 1 so that the dust 40 a is generally located on the left side of the inclined surface that passes through the rotation center of the furnace 1 and the lift release point P (hereinafter, the “stirring area”). ), The mixture is repeatedly mixed and stirred in Y.

The electric heating element groups 16 are similar to those shown in FIGS.
As shown in the figure, the dust 40a is arranged so as to pass through a region Z (hereinafter, referred to as a "non-stirring region") deviating from such a stirring region Y, and when the dust 40a is mixed and stirred by the rotational driving of the furnace body 1, Also, the dust 40a is devised so as not to directly touch the electric heating elements 16. The heat generation capacity and the number of heaters of the electric heating element 16 are appropriately set according to processing conditions such as the amount of accumulated dust in the furnace body 1 on condition that the inside of the furnace body 1 can be heated to about 1000 ° C. as described above. .

A dust supply mechanism for supplying dust 40a discharged from the refuse incinerator into the furnace body 1 is provided on the first lid 9 for sealing the front end, which is the upper end of the furnace body 1. 17
Are connected. That is, as shown in FIGS. 1 and 2, the mechanism 17 includes a supply port 18 formed in the lid 9, a supply hopper 19 connected to the supply port 18, and a pusher 20 disposed at a lower end of the hopper 19. And Pusher 2
0 moves forward and backward in the front-rear direction due to the expansion and contraction operation of the cylinder 20 a, so that the dust 40 a in the hopper 19 is quantitatively supplied to the supply port 18.
From the furnace body 1. Thus, the supply port 18 is
As shown in FIG. 4, it is formed at a position substantially at the same height as the center of rotation of the furnace body 1 and at a position close to the ascending peripheral wall portion 1'a, so that the dust 40a interferes with the electric heating elements 16. Instead, it can be supplied to the stirring area Y. The region from the hopper 19 to the supply port 18 is always filled with dust 40a, so that the supply port 18 is so-called material-sealed. That is, care is taken so that the airtightness in the furnace body 1 is not impaired by opening the supply port 18 in the lid body 9.

Further, a processing ash discharging mechanism 21 for discharging the processing ash 40b out of the furnace 1 is connected to the second lid 10 which seals the rear end, which is the lower end of the furnace 1. Have been.
That is, as shown in FIG.
And an ash conveyor 24 which is connected to the discharge port 22 via a discharge pipe 23. The discharge port 22 is opened at the lowest end region in the furnace body 1, and the processing ash 40 b in the furnace body 1 is quantitatively discharged by a rotary feeder 25 interposed in a discharge pipe 23 so that the ash extraction conveyor 24 The paper is supplied to the transport start end.
The driving device 26 of the rotary feeder 25 is mounted on the inclined table 4.
And the conveyor connection portion 23a of the discharge pipe 23 has a structure having flexibility and elasticity,
It is devised so as to cope with a change in the inclination angle θ of the inclination table 4. Further, the area from the outlet 22 to the rotary feeder 25 is always filled with the processing ash 40b.
So-called material seal, and the lid 1
By opening the discharge port 22 at 0, care is taken so that the airtightness inside the furnace body 1 is not impaired.

Further, an exhaust mechanism 27 for discharging the exhaust gas 40c generated in the furnace body 1 is connected to the first lid body 9. That is, as shown in FIGS. 1 to 4, the mechanism 27 has an exhaust port 28 that opens to the non-stirring zone Z at the upper end of the lid 9, and the exhaust port 28 has a cooling port such as a gas cooler. The exhaust gas 40c is discharged from the exhaust port 28 to the atmosphere through the gas cooler 30, the bag filter 31, and the induction blower 32 by connecting the exhaust line 29 provided with the filter 30, the dust collector 31 such as a bag filter, and the induction blower 32. It is supposed to.

According to the detoxifying apparatus for refuse incineration soot and dust constructed as described above, the inside of the furnace body 1 is heated and held at about 1000 ° C. by the electric heating elements 16 and the furnace body 1 is driven to rotate in the X direction. In this state, the dust 40 a is supplied from the supply port 17 into the furnace body 1 by the pusher 20.
The dust 40a can be efficiently and effectively detoxified.

That is, when the dust 40a is supplied from the supply port 18 into the furnace body 1, the front side of the dust 4a is heated by the radiant heat from the electric heating elements 16, and on the other hand, the back side (contact with the peripheral wall 1a). Is heated by the heat transfer from the peripheral wall 1a. As described above, the dust 40a is repeatedly mixed and agitated by repeatedly rising and falling as described above with the rotation of the furnace body 1 (see FIG. 4). Given to. This mixing and stirring operation is reliably performed because the inner peripheral surface of the furnace is formed as the uneven surface 1b as shown in FIG. By the way, furnace body 1
The rotation speed (peripheral speed of the inner peripheral surface of the furnace) is set according to the properties of the dust 40a and the like so that the mixing and stirring action is effectively performed. / S is preferable.

Then, the dust 40a sequentially flows backward along the inclination of the furnace body 1 while being mixed and stirred as described above. Therefore, during this time, the dust 40a is uniformly and sufficiently heated (about 1000 ° C.),
The decomposition of dioxins and the volatilization of heavy metals contained in water are efficiently performed.

By the way, in the dust 40a, Cr ⁶⁺
Exists in a stable state as Cr ³⁺ , but as described at the beginning, Cr ³⁺ has a property that it is easily oxidized to Cr ⁶⁺ by high-temperature heating in air. But,
The inside of the furnace body 1 is sealed by lids 9 and 10, and the dust 4
Since the heating of 0a is performed in a reducing atmosphere in which air does not enter, Cr ³⁺ contained in the dust 40a does not change to Cr ⁶⁺ . That is, unburned carbon contained in the dust 40a is burned in the closed space in the furnace body 1 to generate CO, and Cr ³⁺ is converted to C ³ by the reduction action of the CO.
Oxidation to r ⁶⁺ is effectively suppressed.

Further, since the electric heating elements 16 are located in the non-stirring zone Z, the dust 40a supplied from the supply port 18 or the dust 40a to be mixed and stirred does not directly touch the electric heating elements 16. In addition, the electric heating element 16 is not damaged by the adhesion and burning of the dust 40a, and the durability of the electric heating element 16 is greatly improved.

The detoxified dust, that is, the treated ash 40b, flows down along the inclination of the furnace body 1 to the rear end of the furnace body 1 as described above, and then is operated from the discharge port 22 by the operation of the rotary feeder 25. It is discharged and brought to a predetermined ash processing section by the ash conveyor 24.

On the other hand, exhaust gas 40c generated in the furnace body 1
Is exhausted from an exhaust port 28 to an exhaust line 29 by an induction blower 32, cooled by a gas cooler 30, collected and removed by a bag filter 31 for dust (a very small amount) and volatile matter, and then discharged to the atmosphere. Released during.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.

For example, the residence time and transfer speed of the dust 40a in the furnace body 1 are extremely important factors for stabilizing the treatment performance and improving the treatment efficiency. In order to keep the number, the following measures can be taken. That is, both lids 9, 1
0, a level detector for detecting the upper and lower limit levels of the dust 4a in the furnace body 1 is provided.
Is provided with a piezoelectric measuring device capable of measuring the weight of the apparatus main body such as the inclined table 4 and the furnace body 1 supported by the inclined table 4, and continuously detects a change in the amount of dust in the furnace body 1, Supply amount by the pusher 20 and the rotary feeder 25 based on the
It is configured to control the amount of discharge due to.

The electric heating element 16, the dust supply mechanism 17, the treated ash discharge mechanism 21, and the exhaust mechanism 27 are all connected to the fixed lids 9 and 10, so that the movable furnace 1 Thus, there is no structural restriction as in the case of connecting them to each other, and an optimal configuration according to the processing conditions can be achieved.

[0036]

As is apparent from the above description, according to the detoxification apparatus for refuse incineration dust of the present invention, the dust in the furnace is heated to about 1000 ° C. while mixing and stirring, so that the dust is evenly distributed. To be able to efficiently decompose dioxins and volatilize heavy metals in a short time,
Detoxification treatment equivalent to the case of melting dust can be realized. Moreover, unlike the dust melting device, the device structure is simple, the operation management and maintenance management are easy, and the cost required for these is low.

Further, since the heat treatment is performed in a state where the furnace body is sealed and the air is shut off, the change of Cr ³⁺ to Cr ⁶⁺ in the treated ash can be performed regardless of the cooling condition of the treated ash. , Can be effectively suppressed.

Further, since the electric heating element, the dust supply mechanism, the treated ash discharge mechanism, and the exhaust mechanism are connected to the fixed cover, there are structural restrictions such as the case where they are connected to the movable side. Therefore, the degree of freedom in design is extremely high, and the design and maintenance are extremely easy. Therefore, the electric heating element can be arranged in the in-furnace area (non-stirring area Z) where the electric heating element does not directly contact with the dust, and by doing so, the durability of the electric heating element can be greatly improved.

Furthermore, by providing the furnace body and both lids forming a closed heating space as a heat-insulating refractory structure, the heat efficiency becomes extremely high in combination with the above-mentioned mixing and stirring of the dust. It is possible to greatly reduce the power consumption unit required for the above, and to realize extremely economical dust harmless treatment.

Further, by forming the inner peripheral surface of the furnace body as an uneven surface in which convex ridges or grooves extending in the axial direction are arranged in parallel in the circumferential direction, the above-mentioned mixing and stirring of dust can be performed more reliably and better. As a result, the processing efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing one embodiment of a detoxification processing apparatus according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged detail view showing a main part of FIG. 2;

FIG. 4 is an explanatory view corresponding to FIG. 2 and illustrating a stirring state of dust;

FIG. 5 is a graph showing the relationship between the volatilization rate of heavy metals and heating time.

[Description of Signs] 1 ... furnace body, 1a ... peripheral wall, 1b ... inner peripheral surface (irregular surface), 1c
... convex ridge, 1d ... concave groove, 2 ... support mechanism, 4 ... inclined table, 5 ...
Support roller, 9: first lid, 10: second lid, 11: sealing material, 12: drive mechanism, 16: electric heating element, 17: dust supply mechanism, 18: supply port, 21: treated ash discharge mechanism, 22 ...
Outlet, 27 ... exhaust mechanism, 28 ... exhaust port.

Claims (4)

(57) [Claims] 1. A cylindrical furnace body, first and second lids for sealing both ends of the furnace body so as to be rotatable relative to each other, and both the lids are fixedly supported and the furnace body is rotatable in an inclined state. A supporting mechanism for supporting, a driving mechanism for rotating and driving the furnace body in a certain direction,
A rod-shaped electric heating element penetrating through the furnace body and fixedly supported by both lid bodies, and being heated and maintained at 1000 ° C. inside the furnace body, and a first lid body that seals a high-side end of the furnace body are connected to each other. A dust supply mechanism that supplies dust into the furnace, a processing ash discharging mechanism that is connected to a second lid that seals a lower end of the furnace, and that discharges processing ash from the furnace; A detoxification apparatus for refuse incineration dust, comprising: an exhaust mechanism connected to one lid and discharging exhaust gas from the furnace body. 2. The detoxifying apparatus for refuse incineration dust according to claim 1, wherein the electric heating element is disposed in an area inside the furnace that does not directly contact the dust. 3. The detoxification apparatus for refuse incineration dust according to claim 1, wherein the furnace body and the both lids are made of a refractory structure having heat insulation properties. 4. An inner peripheral surface of the furnace body is characterized in that a plurality of ridges or concave grooves extending over the entire width in the axial direction are formed on an uneven surface which is arranged at predetermined intervals in the circumferential direction. Do
The detoxifying apparatus for refuse incineration dust according to claim 1, claim 2 or claim 3.