JP3590619B2 - Combustion ash heat treatment equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustion ash heat treatment apparatus, and more particularly, to a combustion ash heat treatment apparatus that can more efficiently treat organic halogen compounds such as dioxins contained in combustion ash.
[0002]
[Prior art]
Combustion ash (mainly fly ash and main ash) discharged from refuse incineration facilities includes dioxins, which are small amounts of aromatic halogen compounds that are highly toxic to the human body, or trichlorethylene and tetrachloroethylene. An aliphatic organic halogen compound may be contained. Therefore, recently, various processing apparatuses for further heating the combustion ash in order to decompose the above-mentioned organic halogen compounds have been studied.
[0003]
For example, Japanese Patent Application Laid-Open No. 7-328583 discloses a heat treatment apparatus ("a heat dechlorination treatment apparatus for dust ash") for completely burning unburned components in combustion ash and decomposing chlorine compounds. I have. Such a heat treatment apparatus has a vertically long cylindrical apparatus main body containing ash, a stirring screw arranged along the axis of the apparatus main body, a heating means for heating the apparatus main body, and a height of the apparatus main body. A heating air inlet provided in the center is provided, and the ash supplied from the upper inlet of the apparatus main body is stirred in a direction to be lifted by the screw while being heated in the apparatus main body, and the air is supplied from the center of the apparatus main body. It is configured to supply.
[0004]
In the above-mentioned heat treatment apparatus, by forming a stirring fluidized bed in the upper half of the apparatus main body, the contact between air and ash is promoted to completely burn unburned components, and a low By forming a moving layer at an oxygen concentration and in a high-temperature atmosphere, chlorine compounds in the ash are decomposed.
[0005]
[Problems to be solved by the invention]
By the way, while sufficient air is required to completely burn unburned components in the combustion ash, incorporation of air must be reduced as much as possible to decompose chlorine compounds. However, in the above-described heat treatment apparatus, when the supply amount of air is increased to completely burn unburned components in the upper part of the apparatus main body, a large amount of air is entrained to the lower part of the apparatus main body. If the chlorine compound cannot be sufficiently decomposed and the supply amount of air is reduced in order to surely decompose the chlorine compound, unburned components may be exhausted without being completely burned. Therefore, in order to completely burn the unburned components and reliably decompose the chlorine compound in the heat treatment apparatus having the above-described structure, more accurate adjustment of the air supply amount and a sufficient residence time are required.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a combustion ash heat treatment apparatus that can more efficiently treat unburned components and organic halogen compounds such as dioxins contained in combustion ash. To provide.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a combustion ash heat treatment apparatus, a structure of a processing tower partitioned into a plurality of processing chambers, a structure of stirring the combustion ash for each processing chamber, and each processing chamber. By adopting a structure that can supply air by controlling the flow rate every time, a necessary and sufficient residence time is secured, and the combustion process of the unburned components in the combustion ash and the decomposition process of the organic halogen compound are respectively adapted. Supply an appropriate amount of air.
[0008]
In other words, the gist of the present invention is a combustion ash heat treatment apparatus for decomposing an organic halogen compound by heat-treating a combustion ash containing an organic halogen compound, wherein the combustion ash is supplied from above and treated combustion ash is provided. The processing tower includes a cylindrical processing tower from which ash is discharged from below, a heating unit provided on an outer periphery of the processing tower, and an air supply unit that supplies air to the processing tower. A plurality of processing chambers are vertically divided by a floor plate having a ash drop hole, and each of the processing chambers is rotatable on an upper surface side of the floor plate with a stirring means for stirring the combustion ash supplied to the processing chambers. And a turntable having a large number of combustion ash passage holes formed at positions that can be superimposed on the drop holes, and the air supply means can supply air by controlling the flow rate for each of the processing chambers. Have multiple air supply pipes It consists in a heat treatment apparatus for combustion ash, wherein.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a combustion ash heat treatment apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a structure of a main part of a combustion ash heat treatment apparatus according to the present invention. FIG. 2 is a perspective view, partially broken away, showing the structure of a processing chamber provided inside the processing tower. Hereinafter, in the description of the embodiment, the heat treatment device for combustion ash is abbreviated as “heat treatment device”.
[0010]
The heat treatment apparatus of the present invention is an apparatus for subjecting combustion ash containing an organic halogen compound to a heat treatment to decompose the organic halogen compound. Combustion ash is discharged from incineration facilities that treat municipal waste and industrial waste. In the present invention, combustion ash is mainly captured by an electric dust collector, a bag filter, a multi-cyclone, or another dust collector. Examples include fly ash collected and main ash that is a combustion residue. The above-mentioned combustion ash may contain slaked lime as a hydrogen chloride scavenger blown into the incinerator flue, activated carbon as a dioxin-type adsorbent, sand particles, and the like. Examples of the organic halogen compounds contained in the combustion ash include dioxins which are aromatic halogen compounds, that is, compounds in which hydrogen such as dibenzo-p-dioxin and dibenzofuran are substituted with chlorine, and aliphatic organic compounds such as trichloroethylene and tetrachloroethylene. Halogen compounds.
[0011]
In the present invention, in heat-treating the combustion ash, from the viewpoint of more efficiently decomposing the organic halogen compound, the combustion ash to be subjected to the heat treatment is preferably combustion ash in which an organic halogen compound decomposition catalyst is previously mixed. . As organic halogen compound decomposition catalysts, catalysts such as iron oxide, and catalysts based on iron oxide and / or titanium dioxide are known (Japanese Patent Publication No. 6-38863, JP-A-2-280816, JP-A-11-188235). And JP-A-11-188236).
[0012]
As the organic halogen compound decomposition catalyst, a composite catalyst of iron compound particles and an amine compound is particularly effective. Among such composite catalysts, the phosphorus content is 0.02% by weight or less, the sulfur content is 0.3% by weight or less, the sodium content is 0.3% by weight or less, and the average particle size is 0.01 to 2%. A composite catalyst of 0.0 μm iron compound particles and an amine compound, having an apparent density (ρa) of 0.8 g / ml or less and the iron compound particles in air at 300 ° C. for 60 minutes. 50 mg of a composite of the iron oxide powder obtained by the heat treatment and the above-described amine compound was mixed with 5.0 × 10 ⁻⁷ mol of monochlorobenzene and a temperature of 300 ° C. in an inert gas atmosphere using a pulse type catalytic reactor. More preferably, a composite catalyst having an activity capable of decomposing 50% or more of the monochlorobenzene when contacted instantaneously under the condition of SV = 150,000 h ^-1 is more preferable.
[0013]
As the iron compound particle powder of the above composite catalyst, one or more particle powders selected from iron oxide particle powders such as goethite, akagenite, lepidocrocite and the like, and iron oxide particle powders such as hematite, maghemite and magnetite And preferably goethite, hematite, and magnetite are used. Examples of the amine compound include one or more compounds selected from alkylamines such as diethylenetriamine and triethylenetetramine, alkanolamines such as triethanolamine and diethanolamine, and cyclic amines such as aniline. .
[0014]
By adding the above-described composite catalyst to the combustion ash, oxidative decomposition is further enhanced, so that the heat treatment in the presence of oxygen is further facilitated. For the combustion ash to be subjected to the heat treatment, the organic halogen compound decomposition catalyst may be a common dry mixing method using a sand mill, a Henschel mixer, a concrete mixer, a Nauta mixer or the like, or a single-shaft and twin-shaft kneader-type mixer. Mix according to the semi-dry mixing method used and adding water as needed. The addition amount of the organic halogen compound decomposition catalyst is usually 0.1 to 100 parts by weight, preferably 1.0 to 50 parts by weight, more preferably 1.0 to 30 parts by weight based on 100 parts by weight of combustion ash. .
[0015]
As shown in FIG. 1, the heat treatment apparatus of the present invention heats the processing tower and a cylindrical processing tower (1) from which combustion ash is supplied from above and treated ash is discharged from below. For this purpose, a heating means (6) provided on the outer periphery of the processing tower and an air supply means (7) for supplying air to the processing tower (1) are provided.
[0016]
The treatment tower (1) is a heating furnace having heat resistance and corrosion resistance for heat-treating the supplied combustion ash, and is usually formed in a long-axis cylindrical shape. Internal volume of the processing tower (1) is be designed appropriately in accordance with the processing amount, typically it is about 0.2~1m ^3.
[0017]
The ceiling of the treatment tower (1) is provided with a hopper (2) for introducing combustion ash into the treatment tower, and is discharged from the incineration facility by the hopper (2) as described above. The combustion ash to which the catalyst has been added is continuously supplied into the treatment tower (1). In addition, an exhaust pipe (5) for discharging gas such as water vapor and carbon dioxide generated in the processing tower (1) is provided at a ceiling portion of the processing tower (1). The exhaust pipe (5) is adapted to supply air to an intermediate portion in order to reduce the temperature and component concentration of the exhaust gas, and to supply the diluted exhaust gas to an exhaust gas treatment device (abatement device). Has been done.
[0018]
On the other hand, at the bottom of the processing tower (1), a discharge pipe (3) for discharging the treated combustion ash to the outside of the system is provided, and a screw conveyor (4) is provided downstream of the discharge pipe (3). Be placed. Then, the treated combustion ash is transferred to a collection container (not shown) or the like by the discharge pipe (3) and the screw conveyor (4). In addition, it is preferable that the discharge pipe (3) is configured to be heatable by a heater in order to prevent adhesion of the treated combustion ash.
[0019]
The inside of the processing tower (1) is divided into a plurality of processing chambers vertically by a floor plate (10) to heat and supply air in accordance with the progress of the processing of the combustion ash. Specifically, the inside of the processing tower (1) is partitioned into three to five processing chambers (1A). In the apparatus illustrated in the figure, it is divided into four processing chambers (1A).
[0020]
Also, as shown in FIG. 2, the floor plate (10) is provided with a drop hole (10c) for sequentially moving the combustion ash to a region below. The drop holes (10c) of the floor plate (10) of each processing chamber (1A) are positioned so as not to overlap each other when viewed in a plan view, for example, the upper and lower floor plates, in order to prevent a through path of untreated combustion ash. In (10), the phase is shifted by 180 degrees.
[0021]
Each of the processing chambers (1A) stirs the stored ash and stirs the combustion ash supplied to these processing chambers in order to promote the combustion of unburned components and the decomposition of the organic halogen compound. ) And a turntable (12) rotatably arranged on the upper surface side of the floorboard (10). A drive shaft (11) that rotates at a constant speed in one direction by a geared motor is inserted through the processing tower (1) along the center line of the processing tower (1). It is constituted by a stirring rod attached to the drive shaft (11).
[0022]
The turntable (12) of each processing chamber (1A) is configured to be rotatable integrally with a stirring rod (stirring means (13)) by being attached to a drive shaft (11). Each turntable (12) is formed with a large number of holes (12c) for burning ash at positions that can be superimposed on the falling holes (10c) of the floor plate (10). Through the passage hole (12c) superimposed on the drop hole (10c) of the floor plate (10) to the lower processing chamber (1A) or the discharge pipe (3).
[0023]
Further, on the upper surface side of the turntable (12), in order to move the combustion ash to the lower processing chamber (1A) or the discharge pipe (3) more smoothly, the combustion on the turntable is performed by rotating the turntable (12). A scraper (14) for relatively moving the ash in the circumferential direction is arranged. The scraper (14) is formed of a band-shaped plate and is installed in a state of being curved in the rotation direction of the turntable (12). One end of the scraper (14) is fixed to the peripheral wall of the processing tower (1), and the other end is slidably mounted on the drive shaft (11) via a tubular member for preventing vibration.
[0024]
The heating means (6) is constituted by a plurality of heaters (61) arranged corresponding to the plurality of processing chambers (1A). Usually, an electric heater is used as the heater (61). The heat generating capacity of the heater (61) is determined according to the temperature of the combustion ash, the throughput, and the like. The heating means (6) includes a plurality of temperature sensors (62) provided in each processing chamber (1A), and each heater (61) is controlled by each temperature sensor (62). ing. Thereby, a necessary amount of heat can be supplied to each processing chamber (1A), and energy costs can be reduced.
[0025]
The air supply means (7) is provided to supply air for burning unburned components in the combustion ash and air for enhancing the catalytic activity when the above-described composite catalyst is used. Can be In the present invention, in order to supply each processing chamber (1A) with air in an amount suitable for the combustion process of the unburned components and the decomposition process of the organic halogen compound in these processing chambers, the air supply means (7) It is important to provide a plurality of air supply pipes (71) that can supply air by controlling the flow rate for each processing chamber (1A).
[0026]
Specifically, the plurality of air supply pipes (71) are obtained by branching a common air supply pipe extending from an air supply tank (not shown) of the compressor toward each processing chamber (1A). The air supply pipe (71) is connected to, for example, each processing chamber (1A) inside the processing tower (1) divided into four sections. Each air supply pipe (71) is provided with a flow detector (72) and a flow control valve (73) that is controlled based on a signal from the flow detector, and each processing chamber (1A). In), air can be supplied at a preset flow rate by controlling the flow control valve (73).
[0027]
In the heat treatment apparatus of the present invention, the supply amount of air to the treatment chamber (1A) is set so as to gradually decrease from the upper stage to the lower stage. That is, the upper processing chamber (1A) mainly burns unburned components in the combustion ash in the upper processing chamber (1A) and mainly decomposes organic halogen compounds in the lower processing chamber (1A). ), A larger amount of air is supplied, and the lower processing chamber (1A) supplies a smaller amount of air. Preferably, the supply amount of air to each processing chamber (1A) is set so as to satisfy the following ratio as a ratio of volume or weight.
[0028]
(Equation 2)
Upper processing chamber: Middle processing chamber: Lower processing chamber = 100: 2-50: 0-30
[0029]
When the inside of the processing tower (1) is divided into four to five processing chambers (1A), in the above formula, the upper processing chamber refers to the uppermost processing chamber, and the lower processing chamber. Means the lowermost processing chamber. The middle processing chamber refers to the second and third processing chambers (1A) from above when partitioned into four processing chambers (1A), and is partitioned into five processing chambers (1A). In this case, it indicates the processing chamber (1A) at the second to fourth stages from the top. When there are a plurality of processing chambers (1A) in the middle stage, the supply amount of air is set so as to gradually decrease from the upper stage to the lower stage between the processing chambers (1A), or is partially equal or partially equal. They are set to be approximately equivalent.
[0030]
For example, when the processing tower (1) is divided into four processing chambers (1A) as shown in the figure, the supply amount of air is set such that the uppermost first processing chamber (1A) is 100%. Then, the second-stage processing chamber (1A) is 20 to 50%, the third-stage processing chamber (1A) is 2 to 40%, and the lowermost fourth-stage processing chamber (1A) is 1 to 30%. It is said. Usually, the supply amount of air to the uppermost processing chamber (1A) is about 50 to 200 liter / min in the case of the processing tower (1) having the above-mentioned internal volume.
[0031]
To treat the combustion ash in the heat treatment apparatus of the present invention, the combustion ash is continuously supplied to the treatment tower (1) through the hopper (2), and the combustion ash is supplied to the uppermost stage in the treatment tower (1). It is sequentially moved from the processing chamber (1A) to the lower processing chamber (1A). The movement of the combustion ash from the processing chamber (1A) to the lower processing chamber (1A) is performed by a natural fall through the passage hole (12c) of the turntable (12) and the drop hole (10c) of the floor plate (10). Is
[0032]
While the combustion ash moves in each processing chamber (1A) in the processing tower (1), in each processing chamber (1A), the combustion ash is heated by the heater (61) while being stirred by the stirring means (13). The temperature of each processing chamber (1A) is set in the range of 350 to 400 ° C. by controlling each heater (61). During the stirring, a predetermined amount of air is supplied to each processing chamber (1A) from each air supply pipe (71), and a required amount of air is mixed with the combustion ash.
[0033]
In the uppermost processing chamber (1A), the water in the combustion ash is mainly removed and the combustion ash is dried by the above-described stirring and heating operations and the supply of air. In the second stage processing chamber (1A), the combustion of unburned components is mainly promoted. In the third processing chamber (1A), the combustion of unburned components and decomposition of organic halogen compounds are promoted. In the lowermost processing chamber (1A), organic compounds are mainly produced under a slight oxygen atmosphere. Decomposes halogen compounds.
[0034]
In the heat treatment apparatus of the present invention, a plurality of air supply pipes (71) capable of supplying air by controlling the flow rate for each processing chamber (1A) are provided. Is set to gradually decrease from the upper stage to the lower stage, so that the unburned components in the combustion ash can be sufficiently burned in the first half, and the organic halogen compounds can be surely decomposed in the second half. .
[0035]
That is, since the steam, the combustion exhaust gas, and the decomposition gas generated by the processing sequentially move upward through the falling holes (10c) of the floor plate (10), the oxygen concentration in the upper processing chamber (1A) tends to decrease. In the heat treatment apparatus of the present invention, as described above, since the supply amount of air is set larger in the upper processing chamber (1A), unburned components are reliably burned in the upper processing chamber (1A). Can be made. Then, since only a necessary amount of air is supplied to the lower processing chamber (1A) for the decomposition reaction, the organic halogen compound can be surely decomposed and its regeneration can be prevented.
[0036]
Further, when an organic halogen compound decomposition catalyst containing a volatile component is used, there is a possibility that the concentration of the volatile component may decrease due to excessive supply of air. However, in the heat treatment apparatus of the present invention, each of the processing chambers ( Since the supply of excess air can be suppressed by controlling the flow rate of air to 1A), a decrease in the concentration of volatile components in the processing chamber (1A) can be prevented, and the catalyst can exhibit sufficient resolution. Further, in the heat treatment apparatus of the present invention, in order to sufficiently dry the combustion ash in the uppermost processing chamber (1A), when the combustion ash is transferred to the lower processing chamber (1A), the combustion ash in these processing chambers may be removed. Adhesion can be reduced, and continuous processing can be performed more smoothly.
[0037]
The steam, the combustion exhaust gas, and the like generated in each processing chamber (1A) by the heat treatment as described above move upward due to the difference in specific gravity, and can be discharged out of the system through the exhaust pipe (5). The treated combustion ash from which the organic halogen compound has been decomposed is passed from the lowermost processing chamber (1A) through the passage hole (12c) of the turntable (12) and the drop hole (10c) of the floor plate (10). It is discharged by a natural fall to a discharge pipe (3), and is carried out of the system by a screw conveyor (4).
[0038]
As described above, the heat treatment apparatus of the present invention has a structure of a processing tower (1) partitioned into a plurality of processing chambers (1A), a structure for stirring combustion ash for each processing chamber (1A), and With a structure that can supply air by controlling the flow rate in each processing chamber (1A), an appropriate amount of air is mixed into the combustion ash according to the combustion process of unburned components and the decomposition process of organic halogen compounds in the combustion ash. Thus, unburned components can be reliably burned with a shorter residence time, and organic halogen compounds can be decomposed.
[0039]
【The invention's effect】
According to the combustion ash heat treatment apparatus according to the present invention, the structure of the processing tower divided into a plurality of processing chambers, the structure of stirring the combustion ash for each processing chamber, the flow rate control for each processing chamber, and air With the structure that can be supplied, an appropriate amount of air can be mixed into the combustion ash according to the combustion process of the unburned components in the combustion ash and the decomposition process of the organic halogen compound, and the unburned components are more efficiently and reliably burned. It can decompose organic halogen compounds.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a structure of a main part of a combustion ash heat treatment apparatus according to the present invention.
FIG. 2 is a perspective view partially broken away showing a structure of a processing chamber provided inside the processing tower.
[Explanation of symbols]
1: treatment tower 10: floor plate 10c: drop hole 11: drive shaft 12: turntable 12c: passage hole 13: stirring means (stirring rod)
14: Scraper 1A: Processing chamber 2: Hopper 3: Discharge pipe 5: Exhaust pipe 6: Heating means 61: Heater 62: Temperature sensor 7: Air supply means 71: Air supply pipe 73: Flow control valve

Claims (6)

A combustion ash heat treatment apparatus that heat-treats combustion ash containing an organic halogen compound to decompose the organic halogen compound, wherein the combustion ash is supplied from above and the treated combustion ash is discharged from below. -Shaped processing tower, heating means provided on the outer periphery of the processing tower, and air supply means for supplying air to the processing tower, the inside of the processing tower is a floor plate having a combustion ash drop hole A plurality of processing chambers are partitioned vertically, and each of the processing chambers is provided with a stirring means for stirring the combustion ash supplied to the processing chambers, and a rotatable arrangement on the upper surface side of the floor plate and the drop hole. A turntable in which a large number of combustion ash passage holes are formed at positions that can be superimposed, and the air supply means includes a plurality of air supply pipes that can supply air by controlling the flow rate for each of the processing chambers. Combustion ash heating process Apparatus. The heating of the combustion ash according to claim 1, wherein the inside of the processing tower is divided into three to five processing chambers, and the amount of air supplied to the processing chambers is set to gradually decrease from the upper stage to the lower stage. Processing equipment. 3. The heating unit according to claim 1, wherein the heating unit includes a plurality of temperature sensors provided in each processing chamber, and a plurality of heaters arranged corresponding to each processing chamber and controlled by each of the temperature sensors. 4. A heat treatment apparatus for the combustion ash according to the above. A drive shaft is inserted into the processing tower along its center line, the stirring means of each processing chamber is constituted by a stirring rod mounted on the drive shaft, and the turntable of each processing chamber is mounted on the drive shaft. The apparatus for heat treating combustion ash according to any one of claims 1 to 3, wherein the apparatus is rotatable integrally with the stirring rod. The scraper for moving the combustion ash on the turntable relatively in the circumferential direction by rotating the turntable is disposed on the upper surface side of the turntable. Heat treatment equipment. The combustion ash heating device according to any one of claims 1 to 5, wherein the combustion ash to be subjected to the heat treatment is a combustion ash containing an organic halogen compound and mixed with an organic halogen compound decomposition catalyst.

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