JP2000093918A - Apparatus for pyrolyzing dioxin in fly ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of thermal conductivity to fly ash in a reactor and to reduce a heating time by a method in which numbers of small impact-applying solid pieces are charged into the reactor, when the pieces raised together with the fly ash by paddles fall, strong impact is applied on the fly ash adherent to the inner wall surface of the reactor, and the fly ash is peeled off. SOLUTION: Fly ash introduced into a reactor 2 is held in an oxygen shortage state and heated while being agitated by a paddle agitator so that dioxin is detoxified by a dechlorination reaction, and decomposed gas is discharged from the reactor 2. In this process, numbers of small spherical solid pieces 7 for peeling off the fly ash adherent to the inner wall surface are charged into the reactor 2. The pieces 7 are lifted with the fly ash by paddles 6 and dropped from the paddles 6 when the paddles 6 are slanted. The fly ash adherent to the inner wall surface of the reactor 2 is peeled off by using impact associated with the falling of the pieces 7. The fly ash is also peeled off by the friction with the pieces 7 lifted by the paddles 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fly ash dioxin pyrolysis apparatus in a refuse incineration plant.

[0002]

2. Description of the Related Art A fly ash dioxin pyrolysis apparatus that decomposes dioxin in fly ash by heating in a reactor while stirring fly ash from a garbage incinerator with a paddle stirrer has been known. In this device, since the length of the rotating shaft of the paddle stirrer is as long as about 5 m, in order to prevent contact between the paddle and the reactor due to thermal expansion or distortion of the shaft, the paddle and the inner wall surface of the reactor are connected. A gap of about 10 mm is provided between them.

[0003]

In the above-mentioned conventional fly ash dioxin pyrolysis apparatus, the fly ash that cannot be lifted up by the paddle in the gap between the paddle and the inner wall surface of the reactor adheres to the inner wall surface of the reactor and solidifies. However, there is a problem that the efficiency of heat transfer to fly ash is reduced.

An object of the present invention is to remove fly ash attached to the inner wall surface of a reactor, thereby improving the efficiency of heat transfer to fly ash in the reactor and shortening the heating time by a fly ash dioxin pyrolysis apparatus. Is to provide.

[0005]

A fly ash dioxin pyrolysis apparatus according to a first aspect of the present invention is a fly ash which decomposes dioxin in fly ash by heat-treating the fly ash in a reactor while stirring the fly ash with a paddle stirrer. In the dioxin pyrolysis apparatus, a large number of solid particles for impact application are placed in the reactor, and the solid particles lifted together with the fly ash by the paddle give an impact to the fly ash attached to the inner wall of the reactor when falling. It is characterized by being stripped off.

[0006] The small solid pieces are lifted by the paddle together with the fly ash, and the fly ash attached to the inner wall surface of the reactor is peeled off by the impact when falling off the paddle. This prevents a fly ash adhesion layer from being formed on the inner wall surface of the reactor, and improves the efficiency of heat transfer to fly ash in the reactor.

[0007] Preferably, the solid particles are spherical. In this manner, the solid small pieces are easily separated from the paddle, and the reactor is prevented from being damaged due to a drop impact of the solid small pieces.

[0008] The solid pieces are preferably metal (eg stainless steel) or ceramic. The reactor is usually made of stainless steel, and the solid small pieces are made of the same material, so that the impact of dropping the solid small pieces becomes sufficient and damage of the reactor due to the impact is prevented. Ceramic small pieces have a smaller drop impact than stainless steel, but are thermochemically stable and can obtain a drop impact large enough to strip fly ash. It is superior to solid metal particles in preventing damage.

[0009] It is preferable that the diameter of the solid piece is 20 to 100 mm. The gap between the paddle and the inner wall of the reactor is 1
It is preferable that the diameter is about 0 mm. For this reason, when the diameter of the solid small piece is 10 mm or less, the solid small piece may not be lifted by the paddle, and when the diameter of the solid small piece is larger than 10 mm and smaller than 20 mm, Small pieces may bite between the paddle and the inner wall of the reactor. Further, when the diameter of the solid small piece is larger than 100 mm, the impact at the time of drop becomes too large, and the reactor may be damaged.

[0010] Before the solid pieces are introduced, 400 to 500
Preferably, it is heated to ° C. In this case, the small solid pieces themselves serve as a heat source for fly ash, so that the fly ash heating efficiency is further improved.

A fly ash dioxin pyrolysis apparatus according to a second aspect of the present invention is a fly ash dioxin pyrolysis apparatus that decomposes dioxin in fly ash by heating in a reactor while stirring the fly ash with a paddle stirrer. At the radially outer ends of the paddles arranged at equal intervals in the axial direction of the rotating shaft, a stripping section for stripping fly ash attached to the inner wall surface of the reactor is provided. .

The paddle stirrer has one
Paddle pairs consisting of two paddles arranged at an interval of 80 ° are provided at equal intervals along the axial direction, and adjacent paddle pairs are arranged so as to be 90 ° apart from each other. .

The stripping portions are preferably arranged at regular intervals in the direction of the rotation axis of the paddle stirrer.

The stripping portion is formed, for example, by a disk cutter. The tip shape of the disk cutter is, for example, a round shape such as a circle. The material is preferably a metal such as stainless steel. It is preferable that the arrangement interval of the disk cutters is set to be equal to or less than 10 times a gap formed between the paddle and the inner wall surface of the reactor.

It is preferable that the disk cutter provided on one of the paddle pairs and the disk cutter provided on the other of the paddle pairs are arranged so as to be staggered along the axial direction. Thereby, a large number of disk cutters are arranged at equal intervals in the axial direction as a whole. The number of disk cutters provided on each paddle is, for example, one disk cutter provided on one of the paddle pairs near the end of the paddle, and one disk cutter provided on the other of the paddles provided at the center of the paddle. It is considered one.

[0016] The stripping portion is formed by a leaf spring formed of a paddle and its radial outer end is urged in a direction in which it comes into contact with the inner wall surface of the reactor. It is formed by a plurality of claws integrally provided at the end. The paddle is made of metal such as stainless steel, and is fixed to a rotating shaft via a paddle shaft.

It is preferable that the claws provided on one of the paddle pairs and the claws provided on the other are arranged so as to be staggered along the axial direction.

[0018]

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

FIG. 1 shows the basic configuration of a fly ash dioxin pyrolysis apparatus according to the present invention. The fly ash dioxin pyrolysis device (1) comprises a reactor (2) having an electric heater (3),
The fly ash is agitated in the reactor (2) and stirred in the reactor (2).
And a paddle stirrer (4) for making the temperature distribution of fly ash in the inside uniform. The paddle stirrer (4) has two paddles (6) arranged at the same location in the axial direction at 180 ° intervals.
Paddle pairs (6) (6) are provided at equal intervals along the axial direction. Adjacent paddle pairs (6), (6) are arranged so as to be 90 ° apart from each other.

According to the fly ash dioxin pyrolysis apparatus (1), the fly ash introduced into the reactor (2) from one end of the reactor (2) has a predetermined oxygen concentration in an oxygen-deficient state (for example, 1 to 2). %) And heated to a predetermined temperature (for example, 350 ° C.) while being stirred by the paddle stirrer (4), whereby the dioxin is rendered harmless by the dechlorination reaction,
Decomposed gas is discharged from the other end of the reactor (2).

FIG. 2 schematically shows a cross section of the fly ash dioxin pyrolysis apparatus according to the first invention. As described above, since the length of the rotating shaft (5) of the paddle stirrer (4) is as long as about 5 m, contact between the paddle (6) and the reactor (2) due to thermal expansion or shaft distortion is prevented. Paddle to prevent
Between the radial outer end of (6) and the inner wall of the reactor (2),
A gap (G) of about 10 mm is provided.
The fly ash adhesion layer having a thickness corresponding to (G) is easily generated.

In FIG. 1, a large number of spherical solid pieces (7) for removing fly ash adhering to the inner wall surface of the reactor (2) are placed in the reactor (2). Therefore, with the rotation of the paddle stirrer (4), the solid pieces (7)
Is lifted together with fly ash (see Fig. (B)).
The paddle (6) falls from the paddle (6) when the inner end of the paddle (6) is inclined so as to face downward (see FIG. (C)). The fly ash attached to the inner wall surface of the reactor (2) is peeled off by the impact of the drop at this time. Fly ash adhering to the inner wall of the reactor (2) is lifted by the paddle (6) and
It is also stripped off by friction with (7).

FIG. 3 shows the results of measuring the heat transfer efficiency when the fly ash adhesion layer was 10 mm, 5 mm, and without. In the figure, the vertical axis represents the temperature in the reactor (2),
The horizontal axis indicates the heating time. According to the figure,
The time for heating the temperature in the reactor (2) to 350 ° C is as follows:
If the fly ash adhesion layer is 10 mm (conventional device), 16
2,000 seconds or more, the fly ash adhesion layer is 5 mm, about 11
000 seconds, without fly ash adhesion layer (this invention)
6000 seconds or less, which shows that the fly ash dioxin pyrolysis apparatus of the present invention can heat the inside of the reactor (2) to a predetermined temperature in about one third of the conventional time.

The solid small piece (7) is preferably made of metal or ceramic and has a diameter of 20 to 100 mm. Further, the solid small piece (7) is preferably heated to 400 to 500 ° C. before being charged into the reactor (2),
As a result, the solid small pieces (7) serve as a heat source for fly ash, and the heating efficiency of the fly ash is improved.

FIGS. 4 and 5 show a first embodiment of a fly ash dioxin pyrolysis apparatus according to the second invention. In the following description, the left and right in FIG. As shown in FIG. 4, in the fly ash dioxin pyrolysis apparatus of the present invention, the paddles (6A), (6B), (6C), and (6D) adhere to the inner wall surface of the reactor (2) at the radial outer ends. A disk cutter (8) is attached as a stripper for stripping fly ash. Here, one paddle pair is denoted by code (6A) (6
B), which are adjacent to the left and right and 9
The other paddle pair shifted by 0 ° is indicated by reference numerals (6C) and (6D). As shown in FIG. 4 (b), one paddle pair (6A) (6
In (B), the paddle of (6A) is provided with one disk cutter (8) near the left and right ends, and the paddle of (6B) is provided with one disk cutter (8) at the center. ing. Similarly, in the other paddle pair (6C) and (6D), the paddle of (6D) is provided with one disk cutter (8) near the left and right end, and the paddle of (6C) is provided with the disk cutter. One cutter (8) is provided at the center. Here, the interval between the two disk cutters (8) provided in (6A) and (6D) is set to 2 W.
The distance from the disk cutter (8) provided in (6C) is W. Further, the distance between the disk cutter (8) provided at the left end of the paddle (6A) and the disk cutter (8) provided at the right end of the paddle (6D) is
W. Thus, multiple disk cutters (8)
Are arranged at equal intervals in the axial direction of the rotating shaft (5).

Disk cutters adjacent in the axial direction
(8) is arranged at a gap (about 10 m) between the radially outer end of the paddle (6A) (6B) (6C) (6D) and the inner wall surface of the reactor (2).
m) It is 10 times or less of (G).

According to the fly ash dioxin pyrolysis apparatus, as shown in FIG. 5, the disk cutter (8) enters the fly ash adhesion layer (9) and causes cracks in the fly ash adhesion layer (9). (9) is destroyed and stripped off.

FIG. 6 shows a second embodiment of the fly ash dioxin pyrolysis apparatus according to the second invention. As shown in the figure, in this fly ash dioxin pyrolysis apparatus, the paddle (10) is a leaf spring formed by forming three metal plates having different lengths with their inner ends overlapped with each other. I have. When the paddle (10) is deformed into an arc shape in cross section, the radially outer end of the paddle (10) is urged in a direction in which it comes into contact with the inner wall surface of the reactor (2). A radially inner end of the paddle (10) is fixed to a radially outer end of a paddle shaft (12) orthogonal to the rotating shaft (11) with a bolt and nut (13). At the outer end of the paddle (10), there is provided a stripping portion (14) formed by bending the outer end of the longest metal plate at a substantially right angle. As shown in FIG. 6 (b), the stripping portion (14) is formed by a plurality of claws (14a) (14b) arranged at equal intervals in the axial direction of the rotating shaft (11). Here, the paddle (10) at the top of the figure
In the figure, five claws (14a) are arranged at equal intervals at the same pitch as the claws (14a), and in the paddle (10) below
One claw (14b) is arranged between the claw (14a) and the claw (14a) of the paddle (10) on the same figure, whereby a plurality of claws (14a) (14b) Are arranged alternately along the axial direction.

According to this fly ash dioxin pyrolysis apparatus, even if the outer end of the paddle (10) approaches the inner wall surface of the reactor (2) due to thermal expansion or axial distortion, it is a leaf spring. Since the paddle (10) is deformed and absorbs it, the stripping section (14) always comes into contact with the inner wall surface of the reactor (2) to strip off the fly ash adhesion layer.

In the above description, the adjacent paddle pairs are arranged so as to be spaced apart from each other by 90 °. However, the adjacent paddle pairs do not have to be displaced from each other, and a predetermined angle other than 90 ° is not required. They may be arranged at intervals.

According to the fly ash dioxin pyrolysis apparatus of the second invention, the fly ash adhesion layer is broken and peeled off, so that the fly ash adhesion layer becomes 0 mm, as shown in FIG.
The heat transfer efficiency is greatly improved as compared with the case where the adhesion layer is 10 mm.

[0032]

According to the fly ash dioxin pyrolysis apparatus of the present invention, it is possible to prevent the formation of an adhering layer of fly ash on the inner wall surface of the reactor and to improve the agitation of the fly ash. The heat transfer efficiency is improved, the fly ash temperature is made uniform, and the desalination reaction of dioxin is promoted. Therefore, the heating time can be significantly reduced, and the apparatus can be made compact and the processing capacity can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a fly ash dioxin pyrolysis apparatus.

FIG. 2 is a diagram schematically showing a fly ash dioxin pyrolysis apparatus of the first invention.

FIG. 3 is a graph showing the effect of the fly ash dioxin pyrolysis apparatus of the present invention.

FIGS. 4A and 4B are diagrams schematically showing a fly ash dioxin pyrolysis apparatus of the second invention, wherein FIG. 4A is a cross-sectional view and FIG. 4B is a plan view.

FIG. 5 is a diagram schematically showing the operation of the fly ash dioxin pyrolysis apparatus of the second invention.

FIGS. 6A and 6B are diagrams schematically showing a fly ash dioxin pyrolysis apparatus of the third invention, wherein FIG. 6A is a cross-sectional view, and FIG. 6B is a vertical cross-sectional view along the line bb in FIG. .

[Explanation of symbols]

 (1) Fly ash dioxin pyrolyzer (2) Reactor (4) Paddle stirrer (6) Paddle (7) Solid pieces (8) Disk cutter (peeling part) (10) Paddle (14) Peeling part (14a ) (14b) Claw

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuhiro Maeda 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi Inside Tachibashi Shipbuilding Co., Ltd. (72) Inventor Yasuo Sato 1-7-89 Minami Kohoku, Suminoe-ku, Osaka No. Tachi Shipbuilding Co., Ltd. (72) Inventor Minoru Hasegawa 1-7-89, Minami Kohoku, Suminoe-ku, Osaka-shi Nippon Shipbuilding Co., Ltd. Issue Date Tate Shipbuilding Co., Ltd. F-term (reference) 2E191 BA12 BD11

Claims (11)

[Claims] 1. A fly ash dioxin pyrolysis apparatus that decomposes dioxin in fly ash by heating in a reactor (2) while stirring the fly ash with a paddle stirrer (4). Many solid particles for impact application
(7) is inserted, and the small solids (7) lifted with the fly ash by the paddle (6) impact the fly ash adhering to the inner wall surface of the reactor (2) when it falls and peel it off. Features Fly ash dioxin pyrolysis equipment. 2. The apparatus for pyrolysis of fly ash dioxin according to claim 1, wherein the solid pieces (7) are spherical. 3. The apparatus for pyrolysis of fly ash dioxin according to claim 2, wherein the solid pieces (7) are metal. 4. The fly ash dioxin pyrolysis apparatus according to claim 2, wherein the solid pieces (7) are ceramic. 5. The apparatus for pyrolyzing fly ash dioxin according to claim 2, wherein the diameter of the solid pieces (7) is 20 to 100 mm. 6. Before the solid piece (7) is charged, 400-
The fly ash dioxin pyrolysis apparatus according to claim 1, which is heated to 500 ° C. 7. A fly ash dioxin pyrolysis apparatus that decomposes dioxin in fly ash by heating in a reactor (2) while stirring the fly ash with a paddle stirrer (4). Fly ash adhering to the inner wall surface of the reactor (2) is attached to the radially outer ends of the paddles (6A) (6B) (6C) (6D) (10), which are arranged at equal intervals in the axial direction of (11). A fly ash dioxin pyrolyzing device, provided with stripping portions (8) and (14) for stripping off ash. 8. A paddle stirrer comprising:
The fly ash dioxin pyrolysis apparatus according to claim 7, wherein the apparatus is arranged at regular intervals in the axial direction of the rotation shafts (5) and (11). 9. The fly ash dioxin pyrolysis apparatus according to claim 8, wherein the stripping section is formed by a disk cutter. 10. The arrangement interval (W) of the disk cutter (8) along the axial direction is equal to the paddles (6A) (6B) (6C) (6D) and the reactor.
(2) The fly ash dioxin pyrolysis apparatus according to claim 9, wherein the gap is not more than ten times the gap (G) formed between the fly ash and the inner wall surface. 11. A paddle (10) is formed by a leaf spring and its radially outer end is urged in a direction in which it comes into contact with an inner wall surface of the reactor (2). (Ten)
A plurality of claws (14a) integrally provided at the radially outer end of the
The fly ash dioxin pyrolysis apparatus according to claim 8, which is formed by: