JPS5855409B2 - Dry ash extraction device for municipal waste incineration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention extracts combustion residue from municipal waste incineration equipment using a dry method, and achieves airtightness with the outside air by eliminating the differential pressure between the inside of the furnace and the outside air without using a sealing mechanism. , relates to a dry ash extraction device for a municipal waste incineration facility, characterized in that the exhaust gas used for that purpose is utilized.

In most cases, combustion residue from municipal waste incineration facilities is extracted using a wet method using a flight conveyor filled with water.

The reason for this is: - The inside of the incinerator can be completely airtight with the outside air using water sealing, which is a very simple method.

■The latent heat of combustion residue can be cooled by water sealing.

Since the transport of the drawn ash from ■, ■ to ■, is carried out at the same time within the same flight conveyor, the equipment cost is low and the performance is stable.

As mentioned above, there is no method superior to this wet water-sealing method for removing municipal waste combustion residue, as it has excellent effects and is cheaper than any other method.

However, recently, water damage has been occurring due to the use of water.

In other words, (1) The leachate taken away from the flight conveyor together with the combustion residue is sent from the residue storage pit to the wastewater treatment facility and discharged after treatment.However, the heavy metals contained in the residue must be removed, so wastewater treatment is required. Equipment becomes complex and expensive.

Even after Yoshiba treatment, the removed settled sludge cannot be dumped as is, and some kind of stabilization measures must be taken. Extra energy must be wasted to perform the processing.

(2) The temperature of the water seal on the flight conveyor gradually rises due to the latent heat of the combustion residue, generating steam.

This steam has a characteristic odor and contains some sulfur dioxide gas and water vapor that corrode metals, which can corrode nearby equipment, so a large amount of make-up water is required to lower the temperature to a point where steam does not form. The capacity of wastewater treatment equipment will be increased to greatly exceed the amount of water absorbed.

(3) There are many examples of so-called semi-humid type ash extraction equipment in other countries, which are intended only for airtightness and rapid cooling of combustion residue, but this type does not allow time for the combustion residue to cool down completely. Therefore, like (2), it is accompanied by undesirable damage such as steam, odor, and corrosion.

As these inconveniences have arisen, a dry ash extraction system, which has not been widely used in the past, has become necessary.

In the wet type, the furnace can be kept airtight simply by submerging the ash removal chute, which is the contact point between the furnace and the flight conveyor, in water sealing water on the conveyor, whereas in the dry type, the negative pressure of around 10 m/m of water is sealed. This requires a mechanism, which is difficult to construct and is inevitably more expensive than the wet method.

However, due to reasons (1) and (2) above, the wet method requires huge equipment costs and maintenance costs for wastewater treatment equipment, and when comparing the overall advantages and disadvantages, there is no way to take advantage of the characteristics of the dry method. It has opened.

This facility is designed to be an afterthought in order to produce less pollution than a garbage incineration facility.

The reason why dry ash extraction equipment was not used was that it was difficult to create an airtight structure.

There is no problem if it is simply isolated from the outside air, but combustion residue is not only the ash left after burning organic matter, but also the unburned remains of the embers, dirt, debris, glass, etc. that are mixed in from the beginning.
The presence of a wide variety of inorganic materials such as ceramics and metals, especially bulky items such as canned goods and oil cans, and long items such as cords, cords, wires, and umbrella ribs, pose obstacles to the design of airtight structures.

For this reason, complex mechanisms that require rotation or sliding are not appropriate as they may lead to failures, and simple mechanisms such as 2
Only structures such as stage dampers can be used.

If the structure is simple, the degree of airtightness is poor, and if airtightness is maintained, intermittent use may result in clinker generation and other damage.

Therefore, it is difficult to design a satisfactory structure with a mechanical mechanism.

Many conventional municipal waste incineration facilities are shown in Figure 1-A and Figure 1.
As shown in -B, the combustion residue is cooled and transferred by the flight conveyor 6 through the ash removal chute 5.

The ash removal chute is connected to the flight conveyor 6 as shown in Figure 1-B.
The water tank 38 is sealed with water to maintain airtightness from the outside air.

On the flight conveyor, there is an air box and dust hopper 4゜4' for dropping the ash and unburned materials that have fallen from the combustion stoker 3 (including dried nutoka) and 3' (including the post-combustion stoker). It is connected through the shoe) 40.40' and is sealed with water like the ash removal chute.

The combustion residue and dust transferred from the flight conveyor 6 are completely immersed in water in this way, so when they are supersaturated with water and are dropped into the ash storage pit 7 and stored, the excess wastewater is stored in the ash storage pit. Since the wastewater accumulates in a large amount, a water collection pit 7a is provided as shown in FIG. 1-A, from which the wastewater from the ash pit is pumped up and sent to a wastewater treatment facility 7b for treatment.

However, although this ash pit sewage is small in quantity compared to the entire plant sewage treated in the wastewater treatment facility 7b, it has a high BOD content due to unburned organic matter in the combustion residue, and because it becomes ash treatment sewage. SS value is also high.

In many cases, various heavy metals are eluted and contained, which has the disadvantage of making wastewater treatment equipment larger and more complex.

In order to eliminate this drawback, it is necessary to eliminate wastewater from the ash pit and, by extension, water removed from the flight conveyor, and to this end, it is necessary to perform ash treatment in a dry manner.

If it is a dry type, it is not easy to design a mechanism to maintain airtightness with the incinerator.

The present invention maintains airtightness without providing a difficult mechanical mechanism, and furthermore, it is a composite system that utilizes the fluid (mixture of air and combustion gas) used as the airtightness means for other purposes. It was developed to have both effects.

A detailed explanation will be given below with reference to the drawings.

In Fig. 2, garbage supplied by a garbage supply crane (not shown) passes through a hopper and a chute 1, and a fixed amount is supplied to a drying and combustion stoker 3 by a supply feeder 2, where it is combusted, and then a combustion and post-combustion stoker 3'. completely ashed,
It falls from the Ashide chute 5 onto the flight conveyor 6.

The combustion gases are in the radiant zones 11 and 11 of the gas-cooled boiler.
It is a normal incineration facility type in which the exhaust gas is cooled in the contact zone 11'', passes through a gas duct 43, is removed by an electrostatic precipitator 13, passes through a gas duct 14 and a suction blower 15, and is released into a chimney not shown in the figure. .

In this incinerator configuration, the present invention does not provide the ash removal chute 5 with a mechanical structure that normally maintains airtightness between the furnace internal pressure of about -10 m/m water column in this part and the outside air, and the flight conveyor 6 is water-sealed. Combustion residue is removed without getting wet.

The combustion residue is transferred as it is by a flight conveyor,
If it falls into the ash storage pit 7, the airtightness between the inside of the furnace and the outside air will not be maintained as there is no airtight mechanism as described above, and a large amount of cold air will enter the incinerator, making it impossible to continue combustion and the ash storage pit 7 It is clear that the dust buildup will result in a very inconvenient working environment.

Therefore, FIG. 3 was prepared for detailed explanation of the present invention.

FIG. 3-A partially shows a compartment of the flight conveyor 6.

That is, the combustion residue enters the first compartment of the flight conveyor 6 from the ash removal chute 5.

The boundaries of the compartments are separated by a curtain 17 made of a heat-resistant flexible material suspended from an upper lid 39.

This curtain 17 is the part shown by diagonal lines in the sectional view of FIG. 3-B, and the hem of the curtain 17 has a length that reaches the bottom of the conveyor tank 38.

The conveyor has a flight 35 that scrapes up and transfers the residue moving along the drive chain 36, so it cannot be completely airtight, but the negative pressure inside the furnace creates ventilation resistance for outside air that tries to enter. If you can, that's fine.

Several such curtains hang down to form the required number of compartments.

The second chamber (FIG. 3-A) is the most distinctive part of the present invention. The upper lid of the second chamber is connected to an inverted conical intake chamber 18 and an intake blower 20 (FIG. 2) that sucks inside air. A suction duct 19 is provided, and automatic control 41 is performed by a damper 42 so that the pressure inside the furnace and the second chamber become the same pressure.

Therefore, the internal pressure of the second chamber is a negative pressure outside the ventilation resistance of the indenter curtain 17 in the furnace.

The outside air has positive pressure, and the final chamber→・・・・・・→4th chamber→3rd chamber
The pressure in the chamber and outside the curtain resistance gradually becomes negative, and the internal pressure in the third chamber becomes approximately the same as that in the first chamber or slightly higher.

Therefore, the intake air sucked into the second chamber is a mixture of mostly outside air and some combustion gas inside the furnace passing through the first chamber.

The second chamber is provided with an air blowing nozzle 28.

Here, a compressor 29 shown in FIG. 2 blows a small amount of high-pressure air through a conduit 30 and directly onto the combustion residue being transferred.

Then, the light ash in the combustion residue is stirred up and this dust is also sucked by the intake blower 20, and the cyclone separator 21
I will have it collected.

The purpose of this is to prevent dust problems in the ash storage pit, but when the outside air passes through the gaps in the curtains inside the flight conveyor, the wind speed becomes quite high, making it impossible to prevent dust inside the flight conveyor.

Rather than preventing this, it is more reliable to forcibly raise dust and remove it separately, and if the removed light ash can be disposed of separately or used as a neutralizing agent, it is a way to kill two birds with one stone.

Returning to FIG. 3-A-, the injection nozzle 39 is installed in the third and fourth chambers.
The reason for this is to spray cooling water into the ash storage pit for finishing purposes to prevent dust. Instead, it uses a known method of using a quenching cooler, which lowers the ambient temperature and cools the residue.

FIG. 3-B is a cross-sectional view of the flight conveyor taken along line a-a', and FIG. 3C is a sectional view of the flight conveyor, and the present invention is applicable to an apron conveyor 37 or a packet conveyor-type transfer device, rather than a flight conveyor-type transfer device. It shows what can be done.

In Figure 2, the ash and unburnt materials that fall from each stoker 3, 3' into the lower air box/dust hopper 4, 4' pass through a chute and are normally led to a flight conveyor as shown in Figure 1-A. As mentioned above, this unburned material is returned to the furnace once again to reduce the amount of heat loss of the entire incineration residue.

Using pneumatic transport, commonly known as the riddling reduction method, is a method generally used in coal-fired boilers, etc., but the present invention is characterized by using air transport after collecting dust in the flight conveyor. ing.

That is, the exhaust from the collection cyclone 21 is carried out through the conduit 22.
A chute 9.9' is connected to this conduit for ash and unburnt material (ridling).

This chute is provided with rotary valves 10, 10' or a flap damper (not shown) for the purpose of airtightness and quantitative supply.

The liquid in the conduit 22 is carried by the suction blower 25, but a cyclone separator 23 and a bag filter 24 are installed in the middle of the conduit to collect it.
It is returned to the incinerator through the conduit 44 for complete combustion, either directly or using a transport device such as the case conveyor 27 or flow conveyor as shown.

The exhaust gas from the ridling suction blower 25 is connected to the inlet of the electrostatic precipitator 13 to collect even the finest dust.

According to the present invention configured in this way, by dry processing the combustion residue of municipal waste incinerators, compared to the conventional wet processing method, the wastewater treatment equipment is simplified by the amount of excess sewage produced by the wet method, and at the same time, the ash It is possible to load overly moist residue from storage pits onto transport trucks, eliminating the pollution caused by dripping sewage onto the streets.

Then, if the dried ash is collected in a system using this device and treated separately with the ash collected by the electrostatic precipitator, which contains a lot of heavy metals, although I did not explain this, it is possible to raise the overall pH. It is convenient for processing.

It will also be possible to incorporate resource-saving pollution prevention equipment into the plan to utilize ash.

Furthermore, the same equipment can also be used with a ridgling reduction device that improves the performance of the incinerator equipment, and its multi-dimensional benefits are immeasurable in terms of pollution prevention, cost reduction, and performance improvement. There is something.

[Brief explanation of the drawing]

FIG. 1-A is an explanatory diagram showing an ash processing device of a conventional municipal waste incineration facility, FIG. 1-B is a sectional view of a flight conveyor taken along line a-a in FIG. 1-A, and FIG. 2 is a municipal waste according to the present invention. 3-A is an enlarged explanatory diagram of the main parts; FIG. 3-B is a sectional view taken along line a'-a' of FIG. 3A; FIG. 3-C is a diagram of b of FIG. 3A. It is a sectional view along line -b. Names of component equipment in the drawing: 1: Garbage hopper and chute, 2: Supply feeder, 3 Nistoker, 4: Air box and dust removal hopper, 5: Ash removal chute, 6: Flight conveyor, 7: Combustion residue storage pit, 8 : Ash removal crane, 9:
Ridding shoe, 10: rotary valve, 11: radiant and contact sawn boiler, 12: boiler drum, 13
: Electrostatic precipitator, 14, 43: Gas dust, 15: Suction blower, 16: E/P ash transfer conveyor, 17: Curtain, 18: Intake chamber, 19: Suction duct, 20; Intake blower, 21, 23: Cyclone Separator, 22,
30, 32, 44: conduit, 24: bag filter,
25: Ridling suction blower, 26: Exhaust duct, 27
: Cane conveyor, 28: Air blowing nozzle, 29: Compressor, 31: Cooling water spray nozzle, 33: Cooling water injection pump, 34: Cooling water tank, 35: Conveyor fly,
36: Drive chain 37: Apron conveyor, 38:
Conveyor water tank, 39: Conveyor top lid, 40: Dust chute, 41: Automatic control device, 42: Damper.

Claims (1)

[Claims] 1. An ash removal chute for dropping combustion residue from a municipal waste incinerator is connected to a flight conveyor, the inside of the flight conveyor is divided into a plurality of compartments, and an automatic control device is operated from one of the compartments. A dry ash extraction device for municipal waste incineration equipment, which prevents outside air from entering the incinerator by sucking inside air with a blower and keeping it at the same pressure as the pressure inside the lower part of the incinerator. 2. Blow compressed air with an air blowing nozzle toward the combustion residue being transferred in the room, which is sucked in by the blower, to forcibly scatter the light ash in the residue, and then suck it in with the blower to remove the transferred combustion residue. A dry ash extraction device for a municipal waste incineration facility according to claim 1, characterized in that it prevents generation of dust when the ash falls into a storage pit. 3 After the dust in the intake air sucked in by the blower is removed by a cyclone separator, it is guided to the lower hopper conduit of the incinerator, and the unburned carbon and drying ash that fall from the incinerator grate air groove is transported as a gas, and the Dry ash from a municipal waste incineration facility as set forth in claim 1 or 2, characterized in that the ash is collected by a cyclone separator and returned to an incinerator to burn unused carbon. Bow-shooting device.