JPH0526421A - Refuse combustion method in dust incinerator - Google Patents

Abstract

PURPOSE:To reduce a rate of remaining unburned gas and to perform a more complete combustion of refuses by a method wherein the unburned gas in the discharged gas generated by the primary combustion is ignited again. CONSTITUTION:Hot primary air is blown from a lower part of each of a drying stoker 5, a combustion stoker 6 and a post-combustion stoker 7 so as to perform a stable combustion of refuse on each of the stokers, and then the generated discharged gas is fed into the secondary combustion chamber 15. In turn, an amount of secondary air corresponding to that of primary air is blown into the secondary combustion chamber 15 from a secondary air blower 11 through an air preheater 23 so as to promote a mixing of the remained unburned gas in the discharged gas. In this case, the amount of secondary air is about 1/1.5 of that of the primary air. In addition, the discharged gas generated through the secondary combustion ascends with the discharged gas generated through the primary combustion and reaches the third combustion chamber 16. In turn, the third air is sucked from the third air blower 12 into the third combustion chamber 16 through a plurality of third air suction nozzles 12A so as to promote mixing with the remained unburned gas in the discharged gas and further to promote the third combustion at the third combustion chamber 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of burning waste in an incinerator for reburning residual unburned gas in exhaust gas from the incinerator.

[0002]

2. Description of the Related Art In general, combustible waste discharged from homes is collected and incinerated in a refuse incinerator as disclosed in Japanese Patent Laid-Open No. 3-28617. Generally, such an incinerator has a hopper to which waste is supplied by a waste crane (not shown), a hopper chute that guides the waste from the hopper, and a waste extruder that transfers the waste of the hopper chute. It is provided with a dust device, a dry stoker that dries the dust supplied by the dust supply device, a combustion stoker that burns the dust from the dry stoker, and a post-combustion stoker that burns the dust from the burning stoker and burns it. The dry stoker, the combustion stoker, and the post-combustion stoker are provided in the lower part of the furnace body, the exhaust gas cooling chamber is formed in the upper part of the furnace body, and the exhaust port for discharging the exhaust gas is formed in the upper end of the furnace body.

High-temperature primary air is blown into the dry stoker, the combustion stoker, and the post-combustion stoker of the furnace body from their respective lower air blowing ports. In the dry stoker, the waste is transferred to the front while being stirred and unraveled, is transported from the dry stoker to the combustion stoker, and is further burned by the combustion stoker while being stirred and unraveled, and is transferred to the front and post-combusted. Carried to the stalker.

A blower, called a furnace cooling fan, provided near the furnace outlet is operated so as to blow air at room temperature when the combustion temperature rises, and is guided to the exhaust gas cooling chamber above the furnace body. The exhaust gas was being cooled.

That is, only when the combustion temperature due to the primary combustion rises, combustion was controlled by blowing cooling air as the exhaust gas temperature control at the furnace outlet of the refuse incinerator.

[0006]

As described above, the blower provided in the vicinity of the furnace outlet is called a furnace cooling fan, and is operated so as to blow it when the furnace temperature becomes high, and the furnace temperature is controlled. However, it was not combustion control. In the secondary combustion of the conventional refuse incinerator, it is better to make the residence time longer by bringing the hot exhaust gas and unburned gas into contact with each other by devising the shape of the furnace body. The re-injection of the reburning air for the secondary combustion was not performed.

Under these circumstances, in recent years, due to the problem of dioxins and the like, achievement of complete combustion of waste has been required. A higher level of complete combustion control has been required from the conventional furnace temperature control, which only requires the furnace temperature to be within a certain range. Achieving complete combustion requires C in the exhaust gas
It is evaluated based on the O concentration, the amount of carbon remaining in the exhaust gas, and the like.

While the purification of the exhaust gas is demanded in this way, the dust in the combustor on the combustion stoker of the furnace body is completely burned or burned in a state close to that, and exhaust gas of complete combustion is generated. In the dry bed on the stoker, since the garbage that has not dried sufficiently is burned, incomplete combustion exhaust gas is likely to be generated.

Therefore, in order to achieve complete combustion of dust, more stable combustion on the primary combustion side (waste supply amount, primary air amount control) and unburned gas in the high-temperature exhaust gas left behind in the primary combustion, In the secondary combustion section, it is required to mix with secondary air to promote secondary combustion.

However, even if an attempt is made to promote the secondary combustion, in the control for sending the primary air to the secondary combustion section for cooling the furnace, the secondary air is not blown in particularly when the temperature of the furnace is lowered, so that the secondary air is not blown. Is insufficient for the primary air amount, or the wind speed for mixing cannot be obtained, and it is far from achieving complete combustion. For example, the CO concentration is 10 to 100 times the peak at the normal furnace temperature. It may be a value.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to reburn unburned gas in exhaust gas generated in primary combustion to reduce the residual rate of unburned gas. It is an object of the present invention to provide a combustion control method in a refuse incinerator that can burn the refuse more completely.

[0012]

SUMMARY OF THE INVENTION The present invention is a waste incinerator waste combustion method for supplying waste air to a stoker of a waste incinerator to burn the waste and leading the waste gas to a furnace body. The secondary air is supplied to the furnace body in an amount corresponding to the primary air so as to promote mixing with unburned gas, and further,
It is characterized in that a predetermined amount of tertiary air is supplied into the furnace body so as to promote remixing with residual unburned gas in the exhaust gas.

[0013]

In the present invention, a secondary air blower provided in the furnace body supplies a predetermined amount of secondary air into the furnace body so as to promote mixing with residual unburned gas in the exhaust gas. , Tertiary air is supplied into the furnace body to promote remixing with residual unburned gas in the exhaust gas.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a refuse incinerator according to an embodiment of the present invention. In FIG. 1, reference numeral 1 indicates a refuse incinerator. The waste incinerator 1 includes a hopper 2 to which waste is supplied by a waste crane (not shown), and the hopper 2
From a hopper chute 3 that guides trash, a dust extruder having a trash chute 3 that transfers trash from the hopper chute 3, a drying stoker 5 that dries the dust supplied by the dust hopper, and a drying stoker 5 It is provided with a combustion stoker 6 that burns the waste and a post-combustion stoker 7 that burns the waste from the combustion stoker 6 and burns it. The waste extruder 4 is provided below the hopper chute 3.
Dry stoker 5, Burning stoker 6, Post-burning stoker 7
Are housed in a furnace body 8, and an exhaust port 9 for discharging combustion gas is formed at an upper end of the furnace body 8. A side wall surface of the furnace body 8 is provided with a cooling water supply port 10 and secondary air. Supply unit 11A of blower 11, cooling water supply port 10 and blower 11 for secondary air
A blower 12 for the tertiary air is provided between the supply sections 11A of the above, and an auxiliary combustion burner 13 is provided at the lower end of the furnace body 8. Inside the furnace body 8, a primary combustion chamber 14 above the dry stoker 5, the combustion stoker 6, and the post-combustion stoker 7,
It is composed of a secondary combustion chamber 15 near the blower 11 for the secondary air, a tertiary combustion chamber 16 above the secondary combustion chamber 15, and a gas cooling chamber 17 above the tertiary combustion chamber 16. The blower 11 for the secondary air is provided directly above the primary combustion chamber 14 of the furnace body 8. The cross section of the furnace body 8 near the tertiary combustion chamber 16 and the gas cooling chamber 17 is formed into a circular shape. As shown in FIG. 2, the wall surface of the furnace body 8 in the tertiary combustion chamber 16 has a blower for tertiary air. A plurality of tertiary air blowing nozzles 12 </ b> A to which air is sent from 12 are circumferentially provided at predetermined intervals. The blowing direction of each of the tertiary air blowing nozzles 12A is a predetermined inclination angle with respect to the wall surface of the furnace body 8 and the same inclination angle with respect to the tangential direction of the furnace body 8, It is designed to generate a swirl of secondary air.

Then, one end of the air supply pipe 18 is connected to the dust pit 19, and the other end side is branched midway to connect to the lower part 8A of the drying stoker 5 of the furnace body 8; The second branch pipe 18B connected to the lower portion 8B of the combustion stoker 6 and the third branch pipe 18B connected to the lower portion 8C of the post-combustion stoker 7.
It constitutes a branch pipe 18C. An air volume adjustment damper 18D, a primary air blower 20 and a primary air temperature adjustment damper 20A are provided in the middle of the air supply pipe 18 described above. In the middle of the first branch pipe 18A, the primary air distribution first
The damper 21A, the primary air distribution second damper 21B is provided in the middle of the second branch pipe 18B, and the primary air distribution third damper 21C is provided in the middle of the third branch pipe 18C.

A discharge pipe 22 is connected to the discharge port 9 of the furnace body 8, and an air preheater 23 and an electrostatic precipitator 24 are provided in this order in the middle thereof. Air supply pipe 18-1
The heat exchange air pipes 25, 25 passing through the air preheater 23 are connected to both side portions of the next air temperature adjusting damper 20A. Exhaust gas in the exhaust pipe 22 and the primary air in the heat exchange air pipes 25, 25 are heat-exchanged with each other via the air preheater 23, and the temperature of the primary air in the air supply pipe 18 becomes high and the exhaust pipe 22 The exhaust gas inside is cooled.

In the present embodiment, however, high temperature primary air is blown into the lower portion 8A of the dry stoker 5, the lower portion 8B of the combustion stoker 6, and the lower portion 8C of the post-combustion stoker 7, respectively, and the dust supply amount, By the air amount control, the dust on the dry stoker 5, the combustion stoker 6, and the post-combustion stoker 7 is stably burned to generate an exhaust gas, which rises in the furnace body 8 and reaches the secondary combustion chamber 15.

On the other hand, an amount of secondary air corresponding to the primary air is blown from the secondary air blower 11 through the air preheater 23 into the secondary combustion chamber 15 with an appropriate blowing speed. In the secondary combustion chamber 15, mixing with the residual unburned gas in the exhaust gas is promoted. Here, the amount of secondary air is
It is set to about 1 / 1.5 of the amount of primary air. Also,
Regarding the secondary air, air at room temperature has been conventionally used for the purpose of cooling the furnace, whereas in the present embodiment, the secondary air is blown mainly for the purpose of secondary combustion. The secondary air is also set to a high temperature, making secondary combustion more effective.

Further, the exhaust gas produced by the secondary combustion rises together with the exhaust gas produced by the primary combustion,
It reaches the tertiary combustion chamber 16. On the other hand, the tertiary air is blown into the tertiary combustion chamber 16 from the tertiary air blower 12 through the plurality of tertiary air blowing nozzles 12A with an appropriate blowing speed, and the tertiary air is blown in the tertiary combustion chamber 16 in the tertiary combustion chamber 16. And the mixing with the residual unburned gas in the exhaust gas that has not yet been burned by the secondary combustion is promoted. In this case, the tertiary air is at room temperature, which makes the cooling of the exhaust gas more effective,
In addition, the furnace body 8 is inserted through the plurality of tertiary air blowing nozzles 12A.
Since the tertiary air at room temperature is blown into it,
It effectively promotes the mixing of the tertiary air and the residual unburned gas in the exhaust gas. In this state, in the tertiary combustion chamber 15,
The tertiary combustion is promoted.

Exhaust gas produced by the primary combustion, secondary combustion, and tertiary combustion is guided to the gas cooling chamber 17 and cooled by the cooling water sprayed from the cooling water supply port 10.
It is guided to the discharge port 9, further cooled from the discharge pipe 22 through the air preheater 23, and reaches the electric dust collector 24. In addition, the cooling operation of the furnace temperature when the furnace temperature rises is appropriately controlled by the operation of the amount of refuse feed.

According to the above-mentioned structure, the secondary air is supplied into the furnace body 8 in an amount corresponding to the primary air so as to promote the mixing with the residual unburned gas in the exhaust gas. The secondary combustion of the residual unburned gas in the generated exhaust gas can be promoted, and thus the residual rate of the unburned gas in the exhaust gas can be reduced and the dust can be burned more completely.

Particularly, even when the furnace temperature is lowered, the secondary air is blown in, and the supply amount of the secondary air corresponds to the primary air amount, so that the secondary air amount does not become insufficient, or , Can obtain the wind speed of the secondary air for mixing,
It is close to achieving complete combustion, for example, the CO concentration can be reduced.

Then, the residual unburned gas in the exhaust gas produced in the primary combustion is secondarily combusted, and the exhaust gas temperature after the secondary combustion is about 800 ° C. to 900 ° C. The residual unburned gas in the exhaust gas can be reburned by sending tertiary air into it and remixing it. Therefore, it is possible to reduce the remaining rate of unburned gas in the exhaust gas and burn the dust more completely.

Moreover, even if the residual unburned gas is almost eliminated in the exhaust gas that has undergone secondary combustion, the cooling effect by blowing in the tertiary air can be obtained. Therefore, the amount of cooling water supplied to the gas cooling chamber 17 of the furnace body 8 can be reduced, the moisture in the exhaust gas can be reduced, and the amount of white smoke discharged from the refuse incinerator 1 can be reduced.

Further, as a measure against dioxin, for example, even in an existing refuse incinerator, the discharge pipe 22 of the furnace body 8
When the exhaust gas temperature at the entrance of the electrostatic precipitator 24 provided in the middle of
In order to control to a target value of 0 ° C. to 280 ° C., it is often necessary to repair the capacity of the gas cooling chamber 17 and the cooling water spray equipment including the cooling water supply port 10 and the like.

Even in such an existing refuse incinerator,
By increasing the secondary air supply as well as the tertiary air supply, the overall cooling capacity of the refuse incinerator is improved,
The cooling target value of the exhaust gas temperature can be achieved without modifying the capacity of the gas cooling chamber 17 or the cooling water spray equipment.

In this embodiment, the amount of secondary air should be the amount corresponding to the primary air, and the amount of secondary air is about 1 / 1.5 of the amount of primary air. However, the air amount of the secondary air is not limited to this value, and the air amount of the secondary air can be proportional to the air amount of the primary air by another appropriate ratio. , It is also possible to have an appropriate functional relationship with the amount of primary air.

[0028]

As described above, according to the present invention,
Secondary air is supplied to the furnace body in an amount corresponding to the primary air so as to promote mixing with the residual unburned gas in the exhaust gas. The combustion can be promoted, and therefore, the residual rate of unburned gas in the exhaust gas can be reduced and the dust can be burned more completely.

Particularly, even when the furnace temperature is lowered, the secondary air is blown in, and the supply amount of the secondary air corresponds to the amount of the primary air, so that the amount of the secondary air does not become insufficient, or , Can obtain the wind speed of the secondary air for mixing,
It is close to achieving complete combustion, for example, the CO concentration can be reduced.

Then, the residual unburned gas in the exhaust gas produced in the primary combustion is secondarily combusted, and the tertiary air is fed into the exhaust gas which has been secondarily combusted to remix it.
It is possible to reburn the residual unburned gas in the exhaust gas. Therefore, it is possible to reduce the remaining rate of unburned gas in the exhaust gas and burn the dust more completely.

Moreover, even if the residual unburned gas is almost eliminated from the secondary combustion exhaust gas, it is possible to obtain the cooling effect by blowing the tertiary air. Therefore, it is possible to reduce the amount of cooling water supplied from the gas cooling chamber of the furnace body, reduce the water content in the exhaust gas, and reduce the amount of white smoke discharged from the refuse incinerator.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refuse incinerator according to an embodiment of the present invention.

FIG. 2 is a sectional view of the furnace body showing a tertiary air blowing nozzle of the furnace body of FIG.

[Explanation of symbols]

 1 Waste incinerator 5 Dry stoker 6 Combustion stoker 7 Post-combustion stoker 8 Furnace body

Claims (1)

What is claimed is: 1. A method for incinerating waste in an incinerator, wherein primary air is supplied to a stoker in an incinerator to burn the waste and introduce the exhaust gas into a furnace body. Supply secondary air in an amount corresponding to the primary air into the furnace to promote mixing with the gas, and further promote a predetermined amount of tertiary air to re-mix with residual unburned gas in the exhaust gas. A method for burning waste in a refuse incinerator, which is characterized in that it is supplied into the furnace body.