JPH05133515A - Method for drying incinerated ash and melting treatment process therefor - Google Patents

Abstract

PURPOSE:To make it possible to dry incinerated ash efficiently and economically by spreading incinerated ash discharged from an incinerator over an after burning stoker of a stoker type incicerator to mix it with unburned matters on the stoker to dry the incinerated ash. CONSTITUTION:Incinerated ash A(wet ash) discharged from an incinerator 1 of municipal refuse or sludge is transported to a drying and melting plant by means of conveyors or trucks and stored in a pit 18. The incinerated ash A in the pit 18 is then fed into an ash hopper 20 by means of an ash feed crane 19 so as to be fed onto a vibrating screen 22 at a constant rate and passed through an ash spreading device 26 and uniformly spread over an after burning stoker 4 of the stoker type incinerator 1 from an incinerated ash feed port 1a, which ash is mixed with unburned matters B of high temperature on the stoker 4 to be dried. And if heating power for drying the ash A is insufficient, an auxiliary burner 7 is actuated to supplement heat. After being dried, the ash is transferred by means of conveyors 9 etc., so as to be subjected to a melting process at an ash melting furnace 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying incinerated ash having moisture and an improvement in its melting treatment method, and is mainly used in an ash melting treatment plant attached to a stoker incinerator. It is something.

[0002]

2. Description of the Related Art Generally, most of the combustion residues discharged from incinerators such as municipal waste, sewage sludge and industrial waste are treated by landfill. However, in recent years, landfills have become tight and it is becoming more difficult to secure them year by year, and along with this, there is an increasing demand for volume reduction of combustion residues.
Further, when the combustion residue is landfilled, there is a risk of environmental pollution due to elution of heavy metals and the like, and therefore there is an increasing demand for environmental protection.

On the other hand, in order to meet the above demands, a so-called incineration ash melting treatment method has been developed and put into practical use in recent years. This is because by melting the incinerated ash, it is possible to reduce the volume and prevent the elution of heavy metals, and the ash can be reused as a resource. By the way, in the ash melting furnace, a burner melting type furnace that heats and melts the incineration ash from the surface with a fuel burner, and an electric melting type furnace that heats and melts the incineration ash by arc heat or Joule heat exist, Regardless of which type of furnace is used, it is advantageous that the water content of the incinerated ash to be fed into the furnace is low, since the melting efficiency of the incinerated ash is increased.

Therefore, when an ash melting furnace is installed at the same time as the construction of an incinerator for refuse, sludge, etc., the incinerator is usually in the form of wet ash extinguished with water as shown in FIG. Instead of taking it out further, a method of taking it out from the incinerator in the form of dry ash extinguished by natural cooling is adopted. That is, as shown in FIG. 5, the combustion residue B discharged from the ash discharge chute 5 of the incinerator 1 through the gas seal damper 6 is extinguished by natural cooling. Then, the cooled dry ash C is sent to the crusher 16 by the dry ash transfer conveyor 9, and foreign substances such as clinker in the ash are crushed. Crushed dry ash C
Is continuously separated into fine dry ash C and iron D through a dry ash vibrating screen 8, a dry ash vibrating conveyor 10, a magnetic separator 11 and the like, and the separated dry ash C is attached to the incinerator 1 by a conveyor 12. It is sequentially supplied into the melting furnace 13.

On the other hand, as shown in FIG. 6, in a refuse incinerator in which a combustion residue B is cooled in water by a so-called flight conveyor 31 to extinguish the fire and a so-called wet incineration ash (wet ash) A is taken out, It is necessary to dry the incineration ash A in the melting process of the incineration ash A. Therefore, generally, the separated incinerated ash (wet ash) A is sent to the rotary kiln type dryer 32, the incinerated ash A is dried by using the exhaust gas E extracted from the ash melting furnace 13 as a heat source, and the dried ash C that has been dried is conveyed 12 Is supplied into the ash melting furnace 13. The exhaust gas E after drying is guided to the incinerator 1. still,
In FIG. 6, 7 is an auxiliary combustion device, and E ₁ is an exhaust gas from the ash melting furnace 13.

[0006]

Therefore, in the ash drying / melting system shown in FIG. 6, it is necessary to convey wet ash, dry ash and ash in an intermediate state between them, and particularly wet ash. In such a case, there is a problem that the ash adhering to the equipment is dried and adhered and the continuous operation of the equipment is easily obstructed, and the work efficiency is extremely low. In addition, in the ash drying / melting system of FIG.
In addition to the ash separation device, a rotary kiln 32 for drying incinerated ash (wet ash) A is additionally required, so equipment costs and maintenance and inspection costs increase, and it is difficult to reduce the ash melting processing cost. There is a problem to say.

On the other hand, in the ash melting system shown in FIG. 5, since the dry ash C is taken out directly from the incinerator 1, although sufficient dustproof measures are required,
Continuous operation of the ash fractionation device and the like becomes easy, and a drying device such as the rotary kiln 32 is not required. However, even in the dry ash receiving type melting furnace as shown in Fig. 5, the incinerator ash (wet ash) A discharged from another existing refuse incinerator or the like is received and simultaneously melted and processed. Cases that have to occur often occur. In order to deal with such a case, it is necessary to additionally install a drying device for incinerated ash (wet ash) A similar to that in FIG. 6 in the system of FIG. There are problems that the operating cost rises, the continuous operation of the melting furnace is disturbed, and the processing efficiency decreases.

The present invention is intended to solve the above-described problems in the conventional drying of incineration ash and its melting treatment, and the incineration ash moistened by using a post-burning stoker in a stoker type incinerator. A method for drying wet incineration ash and a method for melting the same, by efficiently drying A, so that the incineration ash A can be efficiently dried or dried and melt-processed without separately providing a drying device such as a rotary kiln. Is provided.

[0009]

According to the invention described in claim 1, the incineration ash (wet ash) A discharged from another incinerator or the like is sprayed on the post-combustion stoker 4 of the stoker type incinerator 1. The basic constitution of the invention is to dry the incineration ash A by mixing with the combustion residue B on the post-combustion stoker 4 and to take out the combustion residue B and the dried incineration ash A in the dry state to the outside of the incinerator 1. To do.

In the invention according to claim 4, the incinerator ash A discharged from another incinerator or the like is stoker-type incinerator 1
The incineration ash A is sprayed onto the post-combustion stoker 4 to dry it, and the combustion residue B on the post-combustion stoker 4 and the dried incineration ash A are taken out of the incinerator 1 in a dry state, and iron D is also included. The dry ash C after the removal is supplied to the ash melting furnace 13 as a basic constitution of the invention.

[0011]

[Operation] By spraying the moist incineration ash A from the upper side of the furnace side wall onto the post-combustion stoker 4 on which the stoker incinerator 1 is burning dust, the incineration ash A becomes a high temperature combustion residue B on the stoker 4. While being mixed, the high temperature combustion air blown from below the stoker 4 is touched and dried. The dried incinerated ash A is discharged to the outside of the furnace in a dry state together with the combustion residue B on the stoker 4, cooled, and then supplied as dry ash C into the ash melting furnace 13.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a structural explanatory view of a wet incineration ash drying / melting plant used for carrying out the present invention. In FIG. 1, the same reference numerals are used for the portions common to FIGS. 5 and 6 of the conventional example. In the figure, 1 is an incinerator for refuse and the like, 2 is a dry stoker, 3 is a combustion stoker, 4 is a post-combustion stoker, 5 is an ashing chute, 6 is a gas seal damper, 7 is an auxiliary burner, and 8 is dry ash. Vibrating screen, 9 dry ash transfer conveyor, 10 dry ash vibrating conveyor, 11 magnetic separator, 12 conveyor, 13 ash melting furnace,
14 is a metal bunker, 15 is a conveyor, 16 is a crusher,
17 is a conveyor, 18 is an incineration ash pit, 19 is an ash supply crane, 20 is an ash hopper, 21 is an incinerator ash supply pusher, 22 is an incinerator ash vibrating screen, 23 is a conveyor, 2
4 is a gas seal damper, 25 is an incineration ash introduction chute,
26 is an ash disperser, A is moist incineration ash, B is a combustion residue,
C is dry ash and D is iron.

As shown in FIGS. 2 and 3, the ash dispersion device 26 is provided in the vicinity of the incineration ash supply port 1a formed in the upper part of the side wall of the post combustion stoker 4 of the incinerator 1. That is, the ash disperser 26 includes a cylindrical body 26a that is rotatably supported.
And a plurality of ribs 26b fixed to the outer surface thereof and the like, and a driving device (not shown) at a constant speed in the arrow direction.
The incineration ash A is evenly scattered on the post-combustion stoker 4 by being rotated by. Although the incineration ash supply port 1a is provided in the upper part of the furnace side wall in this embodiment, the supply port 1a is provided in the furnace ceiling wall to disperse the ash directly or on the post-combustion stoker using the ash dispersion device 26. You may do it. Further, in the present embodiment, a rotary drum type device is used as the ash dispersion device 26, but in the case where the supply port 1a is provided on the furnace ceiling wall, the upper end of the guide plate is pivoted so that it can swing. It may be a dispersion device 26 of a type that supports the ash to drop it onto a swinging guide plate, or any type of device that can effectively disperse the ash A.

FIG. 4 shows a system for supplying combustion air to the lower part of the stoker of the incinerator 1. Room temperature air S ₁ is passed through the forced draft fan 27 and about 2 air is passed through the air preheater 28.
High-temperature air S ₂ of about 50 ° C. is supplied from below the dry stoker 2, the combustion stoker 3, and the post-combustion stoker 4, respectively. In addition, 29 and 30 are dampers for adjusting the air flow.

Next, the method for drying the wet incinerated ash A and the method for melting the same according to the present invention will be described. Incinerated ash (wet ash) discharged from the incinerator 1 for existing municipal solid waste and sludge
A is carried into the processing plant by a conveyor, a truck, or the like, and stored in the incineration ash pit 18. The stored incinerated ash A is put into the ash hopper 20 by the ash supply crane 19 and is supplied in a fixed amount onto the incinerated ash vibrating screen 22 by the operation of the incinerated ash supply pusher 21. The selected large lumps such as clinker are crushed by the crusher 16 and then returned to the incineration ash pit 18 via the conveyor 17.

Fine ash from the incineration ash vibrating screen 22 is supplied to an ash dispersion device 26 through a conveyor 23, a gas seal damper 24 and an incineration ash introduction chute 25, and is fixed to the body of a cylindrical body 26a rotating at high speed. The ribs 26b evenly spread the ash on the post-combustion stoker 4 through the incineration ash supply port 1a. That is, the scattered incineration ash A is dried by being mixed with the hot combustion residue B on the post-combustion stoker 4. When the amount of heat for drying the incinerated ash A is insufficient, the auxiliary burner 7 is operated to replenish the amount of insufficient heat.

Although the incinerator 1 completely burns dust through the processes of drying, burning, and post-burning, the wet incinerator ash A is transferred to the post-burning stoker 4, which has the least influence on the burning process of dust, It is desirable to apply as evenly as possible the thickness. Further, since the incineration ash A scattered on the post-combustion stoker 4 rides above the high temperature combustion residue B in the post-combustion stage, there is a risk of extinguishing the flame during post-combustion. Therefore, damp incineration ash A
When sprayed on the post-combustion stoker 4, it is desirable to maintain the combustion air supplied from below the post-combustion stoker 4 in a high temperature state and perform aeration drying with high-temperature air (up to about 250 ° C.). That is, by controlling the air volume adjusting damper 29 to open and the damper 30 to close, increasing the combustion air to the post-combustion stoker 4 and raising the temperature thereof, the extinction of the flame due to the spraying of the incineration ash A is prevented. To do.

Further, each of the stokers 2, 3, of the incinerator 1 is
4. The temperature and air volume of the combustion air supplied downward can be arbitrarily adjusted for each stoker as shown in FIG. 4, so that the combustion air S supplied to the upstream drying stoker 2 and the combustion stoker 3 can be adjusted. Even if the incineration ash A is sprayed by adjusting the temperature and air volume of the stoker to a value that suits the quality of the waste, the combustion of the waste on both stokers 2 and 3 will not be affected and will be good. The combustion state can be continued.

The dried incineration ash A is the combustion residue B of the lower layer.
Along with the ash discharge chute 5, it is taken out of the incinerator 1 in a dry state, and as in the case of FIG. 5, the dry ash vibrating screen 8, the dry ash transfer conveyor 9, the dry ash vibrating conveyor 10 and the magnetic separator 11 are used. The fine-grained dry ash C is separated through the above. The separated dry ash C is supplied to the ash melting furnace 13 by the conveyor 12, and so-called ash melting processing is performed here.

[0020]

In the present invention, since the wet incineration ash A is dried by using the post-combustion stoker 4 of the stoker type incinerator, a wet ash drying device such as a rotary kiln and its associated equipment are completely eliminated. This eliminates the need for the equipment, simplifies the equipment, and eliminates the occurrence of problems such as wet ash sticking, which greatly improves the efficiency of drying and drying / melting incinerated ash. Further, water vapor, odor, etc. generated during the drying of the incineration ash A are mixed with the high temperature combustion gas in the incinerator 1 to be deodorized, and are also treated by the exhaust gas treatment device of the refuse incinerator. Therefore, it is extremely advantageous since it does not require a separate treatment facility for gas generated during drying. Further, in the present invention, since the incineration ash A is sprayed onto the post-combustion stoker 4, there is almost no adverse effect on the burning state of the incineration material on the dry stoker 2 and the combustion stoker 3, and the operation of the incinerator 1 The state can always be kept in good condition. In addition, by adjusting the temperature and the air volume of the combustion air supplied from below the respective stokers 2, 3 and 4, the incineration ash A can be efficiently dried while maintaining a good combustion state. Compared to the case where a dedicated dryer is installed, the consumption of auxiliary fuel is also greatly reduced. The present invention is as described above.
It has excellent practical utility.

[Brief description of drawings]

FIG. 1 Drying of wet incineration ash used in the practice of the present invention
It is a structure explanatory view of a melting plant.

FIG. 2 is a schematic vertical sectional view of an incinerator.

FIG. 3 is a sectional view taken along line E-I of FIG.

FIG. 4 is a system diagram for supplying combustion air to the lower part of the stoker of the incinerator.

FIG. 5 is an explanatory diagram of an incinerator ash melting plant attached to a conventional incinerator of a dry ash extraction method.

FIG. 6 is an explanatory view of an incinerator ash drying / melting plant attached to a conventional wet ash extraction type incinerator.

[Explanation of symbols]

A is incineration ash (wet ash), B is high temperature combustion residue, C is dry ash,
D is iron, E is exhaust gas, S is combustion air, 1 is an incinerator,
1a is an incineration ash supply port, 2 is a dry stoker, 3 is a combustion stoker, 4 is a post-combustion stoker, 5 is an ash discharge chute, 6 is a gas seal damper, 7 is an auxiliary combustion burner, 8 is a dry ash vibrating screen, and 9 is dry. Ash transfer conveyor, 10 is a dry ash vibration conveyor, 11 is a magnetic separator, 12, 15, 17 are conveyors, 1
3 is an ash melting furnace, 14 is a metal bunker, 16 is a crusher, 1
8 is an incineration ash pit, 19 is an ash supply crane, 20 is an ash hopper, 21 is an incineration ash supply pusher, 22 is an incineration ash vibrating screen, 23 is a conveyor, 24 is a gas seal damper, 25 is an incineration ash introduction chute, and 26 is Ash disperser,
26a is a cylindrical body, 26b is a rib, 27 is a forced draft fan, 2
8 is an air preheater, 29 and 30 are air volume adjustment dampers.

Claims (5)

[Claims] 1. Incinerator ash (A) discharged from other incinerators, etc.
Is sprayed onto the post-combustion stoker (4) of the stoker incinerator (1) and mixed with the combustion residue (B) on the post-combustion stoker (4) to dry the incineration ash (A), and at the same time, the combustion residue (B) and dried incineration ash (A) are taken out to the outside of an incinerator (1) in a dry state, The incinerator ash drying method characterized by the above-mentioned. 2. The incinerator ash (A) is formed by forming an incinerator ash supply port (1a) above the furnace side wall of the incinerator (1) and using an ash dispersion device (26) provided at the incinerator ash supply port (1a). The method for drying incinerated ash according to claim 1, wherein the composition is sprayed onto the combustion residue (B) of the post-combustion stoker (4). 3. An incinerator ash supply port (1a) is formed on a furnace ceiling wall of the incinerator (1), and the incinerated ash (A) is directly supplied from the incinerator ash supply port (1a) or through an ash dispersion device (26). The method for drying incinerated ash according to claim 1, wherein the) is sprayed onto the combustion residue (B) of the post-combustion stoker (4). 4. The incineration ash (A) sprinkled on the post-combustion stoker (4) is aerated and dried by hot air by adjusting the temperature of the combustion air supplied from below the post-combustion stoker (4) arbitrarily. The method for drying incinerated ash according to claim 1, wherein the ash is dried. 5. The incinerator ash (A) discharged from another incinerator or the like is sprayed onto the post-combustion stoker (4) of the stoker type incinerator (1) to dry the incinerator ash (A), and at the same time. The combustion residue (B) on the combustion stoker (4) and the dried incineration ash (A) are taken out of the incinerator (1) in a dry state, and the iron ash (D) is further removed to obtain the dried ash (C).
Is a method for melting incineration ash so that the ash is supplied into the ash melting furnace (13).