JP3175951B2 - Heated ash treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heated ash treatment device attached to a refuse incinerator for incinerating municipal waste and industrial waste for treating fly ash discharged from the refuse incinerator.

[0002]

2. Description of the Related Art In recent years, in Europe and the United States, the problem of acid rain forests has been highlighted. This is a phenomenon in which sulfuric acid, hydrochloric acid, acetic acid, etc. in the exhaust gas dissolves in raindrops and descends, destroying the forest and creating a dead state called a black forest, especially as harmed by smoke flowing from other countries. It is becoming an international problem and developing into a global environmental problem.

On the other hand, there is no so-called black forest in Japan, but recent soil measurements (acidity) by the Environment Agency indicate PH 4.5 nationwide, which is becoming a problem. By the way, in a refuse incinerator that incinerates municipal waste and industrial waste, there are incineration ash and fly ash as incineration residue, and the exhaust gas contains HCl, SO _X , and NO _x. ,
Further, heavy metals such as Cd and Pb are contained in the dust. Recent waste incinerators in Japan have stricter exhaust gas regulations, so HCl, SO _x , and NO _x removal technologies have advanced.
Although the amount of harmful gas emitted from the chimney is extremely small, it is collected in an electric dust collector in the form of being adsorbed by dust or a desalinating agent and discharged in the form of coexistence with heavy metals such as Cd and Pb. You. Further, in order to remove dioxins and the like present in the exhaust gas together with heavy metals, cases using a bag filter are increasing. If fly ash collected by an electric dust collector or a bag filter was landfilled as it was, it was subjected to a dissolution test (regulated values Pb 3 mg / l, Cd 0.3 mg / l) using fresh water according to Notification 13 of the Environment Agency. Does not pass, it is generally landfilled after solidification of cement.

[0004] On the other hand, a method using an acid for a dissolution test has begun to be carried out in various European countries, and sulfuric acid and hydrochloric acid are used assuming acid rain, and decay of organic matter in a landfill is assumed. Acetic acid is used for each. In Japan as well, dissolution tests with acids have begun to be studied and may be implemented in the near future. Therefore,
In view of these worldwide trends, the inventor conducted an acid elution test of incinerated ash and fly ash discharged from a refuse incinerator. That is, adsorbents of heavy metals such as zeolite, shirasu, black and white, chelate, coral, peat moss and the like were mixed with incineration ash and fly ash at various ratios, and an elution test with an acid was performed. The following Table 1 is an example, and after mixing black and white or liquid chelate and a solidifying agent (using an autoset) into ash and solidifying, an elution test with acetic acid (0.67 regulation) and fresh water was performed. Things.

[0005]

[Table 1]

[0006] As is clear from Table 1, although the water dissolution test specified by the Environment Agency was passed, a large amount of heavy metal was eluted in the acid dissolution test. It turned out that the elution could not be stopped. In particular, fly ash contains more heavy metals and dioxins than incinerated ash,
Further, since the particles are fine, heavy metals and the like are easily eluted, which is a problem. Therefore, in order to prevent the elution of heavy metals, it is necessary to rely on technical treatment in the incineration plant. The following methods are generally known as this technical processing.
A method in which ash is previously washed with acid and the eluted solution is treated with heavy metals. A method in which ash is completely melted at 1400 ° C. in a melting furnace and is taken out as vitrified slag.

[0007]

However, since the above-mentioned method is a liquid treatment, there remains a problem of a waste acid and a problem of a heavy metal sludge treatment, and there are many troublesome practical devices and a problem that it is difficult to put into practical use. . In addition, since the method uses a melting furnace, a large amount of fuel such as electric power, oil, gas, etc. is required, the processing cost is increased, and a large amount of heavy metal is volatilized and collected from the melting furnace. Various problems arise, such as the necessity of a containment process.

[0008] The present invention has been made in view of such problems, and can easily and inexpensively separate heavy metals from ash, and can easily recover and treat separated volatile and non-volatile substances. It is an object of the present invention to provide a heating type ash processing device which can be used.

[0009] The inventor of the present invention has repeatedly performed a number of tests to solve these problems. For example, the inventor of the present application has prepared samples of various types of ash at 200, 400, 60
0, 800, 1000, 1200 ° C., Cd, P
The volatilization test of b was performed. Table 2 below shows the concentrations of Cd and Pb in the ash by heating.

[0010]

[Table 2]

From these results, the volatilization rate at each temperature was obtained and graphed, as shown in FIG. 7 and FIG.
The volatilization rate is negative because the heavy metal content was higher than that at room temperature as a result of the burning loss. As is clear from these graphs, both Cd and Pb
It was found that when the temperature reached 00 ° C., the amount of volatilization rapidly increased and the rate of weight loss also increased. Incidentally, the weight loss up to 600 ° C. is presumed to be due to volatilization of other chlorides and combustion of organic substances. Further, as a result of performing an elution test on the ash after the heavy metal was volatilized using an acid, it was found that the heavy metal hardly eluted.

On the other hand, a large-scale refuse incineration plant normally generates power in a plant. For example, a plant that processes 400 tons of refuse a day can generate about 6500 kWh of power because the calories of the refuse have increased in recent years. Of which, the power used in the plant is about 1800 kWh,
In fact, about 4700 kWh of surplus power is generated and sold to power companies. Therefore, the present inventor paid attention to surplus power generated in a refuse incineration plant equipped with a power generation device, and came up with the idea of using this surplus power for heating fly ash. That is, the temperature at which the heavy metal in the ash is volatilized is 1000
When the temperature is good at about ℃, there is no need to dissolve the ash in the melting furnace, and the inventor of the present application heats the fly ash to about 1000 ° C. using the surplus power to decompose dioxin and at the same time is contained in the ash It has been found that the best method is to volatilize heavy metals such as Cd and Pb to separate them into volatile and non-volatile substances, and then cool and collect the volatile substances.

[0013]

In order to achieve the above object, a heating ash treatment apparatus of the present invention heats fly ash collected from exhaust gas of a refuse incinerator to 1000 ° C. to 1100 ° C.
An electric heater or a burner that decomposes dioxin contained in the ash and volatilizes heavy metals to separate them into volatile and non-volatile substances is provided.
Form the gutter shape and move the furnace bottom from the inlet side to the outlet side.
A fixed heating furnace of a closed type that is tilted and inclined, a leveling device provided in the fixed heating furnace and transferring the fly ash in the heating furnace from the inlet side to the outlet side while stirring, and a fixed heating furnace. A cooling device that is provided in the exhaust gas discharge path and cools the exhaust gas containing the volatile matter discharged from the fixed heating furnace, and a trap that is provided in the exhaust gas discharge path and collects the volatile matter from the exhaust gas that has passed through the cooling device. And a discharge device provided in the fixed heating furnace and capable of discharging only non-volatile substances in the heating furnace. Further, it is preferable that a plurality of rod-shaped electric heating elements are detachably inserted near the ceiling of the fixed heating furnace. Further, the scraping device is composed of a scraping bar that is swingably or rotatably supported by a fixed heating furnace and moves along the furnace bottom, and a drive mechanism that drives the scraping bar. It is preferable that the fly ash in the furnace bottom is transported while being stirred by the swinging or rotating movement of the leveling rod. In addition, it is preferable to provide a temperature detector for measuring the furnace temperature in the fixed heating furnace, and to control the electric heating element or the burner based on the furnace temperature.

[0014]

[Function] Fly ash collected from the exhaust gas of a refuse incinerator by an electric dust collector or the like is supplied to a fixed-rate fixed heating furnace. Fly ash supplied into the heating furnace falls to the bottom of the furnace, and is transferred from the inlet side to the outlet side while being uniformly stirred by the correlation between the swinging or rotating movement of the scraper and the inclination angle of the furnace bottom. In the meantime, it is uniformly heated by radiant heat from the electric heating element. As a result, dioxin contained in fly ash is decomposed, and heavy metals such as Cd and Pb are volatilized and separated into volatile and non-volatile substances. During the operation of the heating furnace, the temperature inside the furnace is detected by a temperature detector so that the temperature inside the furnace always keeps a constant temperature. I have.
Then, the separated volatile matter is discharged from the heating furnace together with the exhaust gas, cooled by the cooling device, and then supplied to the collection device, where it is collected together with the dust. Further, the exhaust gas that has passed through the trapping device is discharged into the atmosphere. In this way,
The volatile matter and dust collected by the collection device are either sealed and landfilled, or used for the regeneration of heavy metals such as Cd and Pb. On the other hand, non-volatile matter, that is, ash containing no heavy metal, at the bottom of the heating furnace is discharged by the discharge device. Since the non-volatile substances have been removed from heavy metals and the like, they can be directly landfilled or used for effective use.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are schematic longitudinal sectional views of a heated ash treatment device according to a first embodiment of the present invention, wherein the heated ash treatment device includes a fixed heating furnace 1, a scraping device 2, a cooling device. It comprises a device 3, a collecting device 4, a discharging device 5, and the like, and is attached to a refuse incinerator (not shown) of a refuse incineration plant with a power generation device.

The stationary heating furnace 1 uses the electric heating element 6 to remove fly ash A collected from the exhaust gas of the refuse incinerator for about 1000 times.
Heated to ℃ to decompose dioxin contained in the ash, and at the same time, it is configured to be able to volatilize heavy metals and separate them into volatile and non-volatile substances. That is, the fixed heating furnace 1 is formed in a box shape by front and rear walls 1a, 1b, left and right side walls 1c, 1d, a ceiling wall 1e, and a bottom wall 1f formed of refractory such as refractory bricks, respectively. A discharge port 7 for discharging non-volatile substances, that is, ash containing no heavy metal, is formed at a lower portion of 1b, and an exhaust port 8 for discharging exhaust gas is formed at one end of the ceiling wall 1e. The heating furnace 1
Is formed in a gutter shape (having a semicircular cross section) and is inclined at an inclination angle of 10 to 20 degrees from the inlet side to the outlet side. The left and right side walls 1c, 1d
A plurality of rod-shaped electric heating elements 6 for heating the fly ash A to about 1000 ° C. are detachably inserted at regular intervals in the upper part of the upper part. The surplus electric power generated by the power generation device of the refuse incineration plant is used as the electric power for heating the fly ash A. Further, a supply device 9 for introducing fly ash A into the heating furnace 1 is disposed on the front wall 1a. The supply device 9 includes a closed hopper 11 having a rotary damper 10 and a hopper 1
1 and a screw feeder 12 that supplies fly ash A to the heating furnace 1 in a fixed amount. The fixed heating furnace 1 is provided with a temperature detector 13 for measuring the temperature inside the furnace, and the inside of the heating furnace 1 is always kept at a constant temperature (100 ° C.).
(About 0 ° C. to 1100 ° C.), the temperature in the heating furnace 1 is detected by the temperature detector 13, and the amount of electricity is controlled by the controller 14.

The scraping device 2 transfers the fly ash A in the heating furnace 1 from the inlet side to the outlet side while stirring, and swings on the front and rear walls 1a and 1b of the fixed heating furnace 1. And a pair of rake bars 15 swinging along the furnace bottom 1f ', and a drive mechanism 16 for alternately driving the pair of rake bars 15 to swing. Specifically, the rake rod 15 is swingably supported by the front and rear walls 1a and 1b via bearings 17 and moves along the arc-shaped furnace bottom 1f '. And a sheath 15b made of a refractory material for covering the cooling pipe 15a. The cooling water is
The cooling water supply pipe 18 enters the cooling pipe 15a via a rubber pipe 19 connected to one end of the cooling pipe 15a.
After cooling, the rubber pipe 2 connected to the other end of the cooling pipe 15a
The cooling water is discharged from the cooling water drain pipe 21 through 0. The driving mechanism 16 includes a motor 22 and the motor 2.
Transmission mechanism 2 interposed between the drive shaft 2 and the cooling pipe 15a
3 and is controlled so as to alternately swing the pair of scraping rods 15 along the furnace bottom 1f 'within a certain angle range. That is, as shown in FIG. 2, the drive mechanism 16 stops one scraping rod 15 at the point b and swings the other scraping rod 15 to transfer the fly ash A toward the point b. After the transfer, the scraping rod 15 is reversed to stop at the point a, and then the other scraping rod 15 stopped at the point b is swung to transfer the fly ash A toward the point a. After the transfer, it is controlled so that it is reversed and stopped at the point b, and the pair of scraping bars 15 are alternately swung in the same manner. Thus, the hearth 1
The fly ash A of f ′ is caused by the swinging motion of the scraper 15 and the hearth 1
According to the correlation with the inclination angle of f ', the mixture is transferred from the inlet side to the outlet side while being uniformly stirred, and is discharged from the outlet 7.

The cooling device 3 is disposed in an exhaust gas discharge path of the fixed heating furnace 1, and cools the exhaust gas including the volatile matter discharged from the fixed heating furnace 1 to about 200 ° C. or less to reduce heavy metals in the exhaust gas. To make it easier to collect. In the present embodiment, a water-cooled or air-cooled jacket type exhaust pipe is used for the cooling device 3, and one end of the exhaust pipe is connected to the exhaust port 8 of the fixed heating furnace 1.

The trapping device 4 is connected to an exhaust pipe serving as the cooling device 3 and traps volatile matter from the cooled exhaust gas. In this embodiment, a bag filter type is used as the collection device 4. Further, a suction ventilator 24 is connected to the outlet side of the collection device 4.

The discharge device 5 is provided near the discharge port 7 of the fixed heating furnace 1 and discharges non-volatile substances in the heating furnace 1, that is, ash containing no heavy metals. In this embodiment, a damper having a sealing function is used for the discharge device 5.

Next, the operation of the above-mentioned heated ash treatment device will be described. Fly ash A collected from the exhaust gas of the refuse incinerator by an electric dust collector or the like is supplied to a closed hopper 11 and is supplied to a fixed-rate heating furnace 1 by a screw feeder 12.
Supplied inside. Fly ash A supplied into the heating furnace 1 falls to the furnace bottom 1f ', and the oscillating movement of the scraping rod 15 and the furnace bottom 1f'.
While being uniformly stirred by the correlation with the inclination angle of f ', it is transferred from the inlet side to the outlet side, and is heated (about 1000 ° C.) evenly by the radiant heat from the electric heating element 6 during that time.
As a result, dioxin contained in fly ash A is decomposed, and heavy metals such as Cd and Pb are volatilized and separated into volatile and non-volatile substances. During the operation of the heating furnace 1, the temperature inside the furnace is always constant (1000 ° C to 110 ° C).
(0 ° C.), the temperature inside the furnace is detected by the temperature detector 13, and based on this, the controller 14 controls the amount of electricity. The separated volatile matter is sucked together with the exhaust gas into an exhaust pipe serving as a cooling device 3, cooled there, sent to a collecting device 4, and collected there together with dust. Further, the exhaust gas having passed through the trapping device 4 is discharged into the atmosphere through the suction ventilator 24. Thus, the collecting device 4
The volatile matter and dust collected in the area are contained and landfilled. That is, a pool-shaped pit made of reinforced concrete is created, and volatiles and the like are put into the pit. When the pit is full, the upper opening is sealed with concrete. The volatile matter is C
It can be used as a raw material for regenerating d, Pb, and the like. On the other hand, non-volatile matter, that is, ash containing no heavy metal, at the furnace bottom 1f 'of the heating furnace 1 is discharged from the discharge port 7 through the damper.
Since the non-volatile substances have been removed from heavy metals and the like, they can be directly landfilled or used for effective use.

FIGS. 3 to 5 are schematic longitudinal sectional views of a heating type ash processing apparatus according to a second embodiment of the present invention. The other configuration is the same as that of the first embodiment. This heated ash treatment device is attached to a refuse incinerator of a refuse incineration plant without a power generation device. That is, an oil or gas burner 25 is disposed on the front wall of the heating furnace 1, and the fly ash A on the furnace bottom 1f 'is heated by the combustion gas from the burner 25. The heating furnace 1 is provided with a temperature detector 13 for measuring the temperature inside the furnace.
(1100 ° C.), the temperature in the heating furnace 1 is detected by the temperature detector 13, and the controller 14 controls the supply amounts of fuel and combustion air based on the detected temperature. In this heating ash treatment device, the burner 25
In order to prevent fly ash A from being scattered by the combustion gas from the fly ash A, the fly ash A absorbs water, and the fly ash A is supplied into the heating furnace 1 in the form of pellets. This heated ash treatment device also has the same operation and effect as the heated ash treatment device of the first embodiment.

Table 3 below shows the results obtained by heating fly ash A at about 1000 ° C. with the above-mentioned heating ash treatment apparatus and then performing an elution test with hydrochloric acid.

[0024]

[Table 3]

As is apparent from Table 3, Cd and Pb hardly eluted from the ash after the heat treatment, and as a result, no problem occurs even if the ash after the heat treatment is landfilled as it is. .

In each of the above-described embodiments, the rod-shaped electric heating element 6 is removably inserted into the left and right side walls 1c and 1d of the heating furnace 1. In other embodiments, the bottom wall of the heating furnace 1 is used. The fly ash A may be heated by burying the electric heating element 6 in 1f or the like.

In each of the above embodiments, a pair of rake bars 15 are provided in the heating furnace 1 and the rake bars 15 are alternately oscillated. In addition, as shown in FIG. 6, the scraping rod 15 may be made into a single piece, and the fly ash A may be transported while being agitated, rotated or rotated forward or backward.

In each of the above embodiments, the scraping device 2
Is water-cooled, but in another embodiment, the scraping device 2 may be air-cooled.

In each of the above embodiments, the furnace bottom 1f 'of the heating furnace 1 is tilted, and the fly ash A is correlated with the swinging motion of the scraping bar 15 and the tilt angle of the furnace bottom 1f'. Is transferred from the inlet side to the outlet side while stirring uniformly, but in another embodiment, the furnace bottom 1f 'is formed horizontally, and the fly ash A is stirred only by the scraping device 2. Alternatively, it may be transferred from the entrance side to the exit side.

[0030]

As described above, the heating ash treatment apparatus of the present invention heats fly ash discharged from a refuse incinerator to the extent that heavy metals are volatilized by an electric heater or a burner, and contains the fly ash contained in the ash. Dioxin is decomposed, and heavy metals are volatilized to separate them into volatile and non-volatile substances, and the volatile substances can be collected from the exhaust gas containing the separated volatile substances. Without the problem of waste acid and heavy metal sludge treatment when liquid is treated with acid,
Also, compared to the case where fly ash is melted in a melting furnace,
In addition to requiring less fuel such as oil and gas, there is no problem in treating heavy metals volatilized in the melting furnace, and heavy metals can be easily and inexpensively separated from fly ash. In particular, when the heated ash treatment device of the present invention is attached to a refuse incinerator of a refuse incineration plant equipped with a power generator, surplus power can be used, so that the treatment cost can be significantly reduced. In addition, the collected volatilized matter is sealed and landfilled, or Cd, P
It can be used as a raw material for regenerating b and the like, which is hygienic and practical. Furthermore, since the non-volatile substances have been removed from dioxins and heavy metals, there is no problem if they are landfilled as they are, and they can be used for effective utilization of ash. Needless to say, the power is only required for the scraping device, and the power is small. In addition, since only the fly ash collected from the exhaust gas can be treated, the size of the heated ash treatment device itself can be reduced. According to the apparatus of claims 2 to 5, in addition to the above effects, the following effects can be further obtained. That is, in the apparatus of the second aspect, since the heating furnace is of a fixed type and has a closed box shape, it is fixedly attached when a cooling device or a discharge device is connected to the heating furnace. And the number of sealing mechanisms can be reduced, and the structure can be simplified. Also, there is no leakage of flue gas including fly ash particles and volatile matter,
Fly ash can be safely and sanitarily processed. Further, since the bottom of the heating furnace is inclined from the inlet side to the outlet side, the fly ash can be easily transferred. In the apparatus according to the third aspect, since a plurality of rod-shaped electric heating elements are detachably inserted near the ceiling of the fixed heating furnace, the electric heating elements can be easily and easily replaced.
In addition, since the electric heating element is attached to the fixed heating furnace, power supply to the electric heating element is also simplified. In the apparatus according to the fourth aspect, the wiping device is supported by the fixed heating furnace so as to be swingable or rotatable, and drives the wiping rod moving along the furnace bottom and the wiping rod. The fly ash can be heated uniformly because the fly ash at the furnace bottom is transferred while being stirred by the swinging or rotating motion of the scraping rod. In the apparatus according to claim 5, a temperature detector for measuring the furnace temperature is provided in the fixed heating furnace, and the electric heating element or the burner is controlled based on the furnace temperature. , And the decomposition of dioxin and the volatilization of heavy metals can be performed reliably and efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional side view of a heated ash treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic vertical sectional front view of the heated ash treatment apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic vertical sectional side view of a heating ash treatment apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic vertical sectional front view of a heated ash treatment apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic longitudinal sectional view of a main part of a fixed heating furnace according to a second embodiment of the present invention.

FIG. 6 is a schematic longitudinal sectional front view showing another embodiment of the scraping device.

FIG. 7 is a graph showing the volatilization rate of Cd in ash.

FIG. 8 is a graph showing the volatilization rate of Pb in ash.

[Explanation of symbols]

A is fly ash, 1 is a fixed heating furnace, 2 is a scraping device, 3 is a cooling device, 4 is a collecting device, 5 is a discharging device, 6 is an electric heating element,
13 is a temperature detector, 15 is a rake bar, 16 is a drive mechanism, and 25 is a burner.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-97774 (JP, A) JP-A-58-58182 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B09B 3/00 303 B09B 5/00

Claims (3)

(57) [Claims] Claims 1. Fly collected from the exhaust gas of a refuse incinerator
The ash is heated to 1000 ° C. to 1100 ° C., provided with an electric heating element or a burner capable of decomposing dioxins contained in the ash and volatilizing heavy metals to separate into volatile and non-volatile substances , and has a box shape. When the furnace bottom is formed into a gutter shape
Closed type with both furnace bottoms inclined from the inlet side to the outlet side
A fixed heating furnace, a leveling device that is provided in the fixed heating furnace and transfers the fly ash in the heating furnace from the inlet side to the outlet side while stirring, and is provided in the exhaust gas discharge path of the fixed heating furnace A cooling device that cools the exhaust gas containing the volatile matter discharged from the fixed heating furnace, and a collecting device that is disposed in the exhaust gas discharge path and collects the volatile matter from the exhaust gas that has passed through the cooling device,
A heating ash treatment device, comprising: a discharge device provided in a fixed heating furnace and capable of discharging only non-volatile substances in the heating furnace. 2. A plurality of rod-shaped electric heating elements are detachably inserted near a ceiling of a fixed heating furnace.
A heated ash processing apparatus according to item 1. 3. A scraping device, comprising: a scraping rod supported swingably or rotatably in a fixed heating furnace and moving along the furnace bottom; and a drive mechanism for driving the scraping rod. 2. The heated ash treatment apparatus according to claim 1, wherein the fly ash at the bottom of the furnace is transported while being stirred by a swinging motion or a rotating motion of the scraping rod.