JP4291524B2 - Stoker-type incinerator and incineration method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stoker-type incinerator used for incineration of incineration objects such as municipal waste and industrial waste, and an incineration method using the same, and particularly to improve the incineration efficiency of the furnace and reduce the amount of unburned gas. The present invention relates to a stoker-type incinerator and an incineration method therefor.
[0002]
[Prior art]
Conventionally, a stoker type incinerator having a plurality of stoker stages having a wind box below has been widely used as an incinerator for incineration of incineration objects such as municipal waste and industrial waste. This stoker-type incinerator has a drying stoker stage (hereinafter referred to as “drying stage”), a combustion stoker stage (hereinafter referred to as “combustion stage”), and a post-combustion stoker stage (hereinafter referred to as “combustion stage”) that are inclined downward and downward at the bottom of the combustion chamber. , "Post-combustion stage") are arranged in a stepwise fashion in the front-rear direction, a dust supply port is provided at the inlet of the drying stage, an ash outlet is provided at the outlet of the post-combustion stage, and secondary combustion is performed above the combustion chamber A room is provided.
[0003]
In the stoker-type incinerator having this configuration, the incinerated material supplied from the dust supply port is dried and sequentially moved on the stocker stage of the drying stage, the combustion stage and the post-combustion stage in order from the dust supply port. Pyrolysis takes place and further combustion occurs. The incinerator supplied to the front part of the drying stage from the dust supply port is dried by the primary air from below and the radiant heat in the furnace in the drying stage. In particular, since municipal waste contains about 50% of moisture, the moisture is evaporated and a part of the pyrolysis is also performed in this drying stage. Thereafter, the combustion stage ignites the dust by the supplied primary air, and burns volatile components and fixed carbon components. The post-combustion stage burns unburned components (mainly fixed carbon components) that have passed without being burned until they completely become ash. The pyrolysis gas generated in the combustion chamber is mixed with the secondary air to reach the secondary combustion chamber where it is burned.
[0004]
A wind box is provided below each stocker stage, and outside air is introduced into the wind box using a blower or the like, for the purpose of cooling the grate or combustion air of the incinerated materials. Primary air is supplied from the grate of each stoker stage. This primary air is introduced into each wind box of each stoker stage from a common blower. In addition, outside air is also supplied to the secondary combustion chamber as secondary air for the purpose of burning unburned gas that could not be combusted in the main combustion chamber.
[0005]
In recent years, it has become indispensable to improve the efficiency of incinerators and reduce the environmental burden. In particular, it is an urgent task to reduce the amount of exhaust gas such as unburned gas and harmful gas. In order to control such pollutants such as dioxins, it is necessary to reduce the unburned content of the combustible gas. For this purpose, the furnace temperature must be increased and the amount of introduced air must be reduced. Is desirable.
[0006]
As a method for increasing the temperature in the furnace and reducing the amount of exhaust gas, for example, supplying oxygen or oxygen-enriched air as primary air or secondary air to promote oxidation is known. As this example, JP-A-3-244913 can be cited. This uses high-concentration oxygen and / or ozone as all or part of primary air and secondary air, detects the exhaust gas temperature and the amount of flue gas in the secondary combustion chamber, and supplies this high-concentration oxygen and / or ozone. By adjusting the amount, the combustion exhaust gas in the secondary combustion chamber is controlled to a high temperature.
[0007]
[Problems to be solved by the invention]
However, in order to evaporate moisture in the drying stage and dry it sufficiently to promote ignition, it is desirable to blow out more primary air, but when the amount of primary air supplied to the drying stage increases, The amount of air introduced that does not contribute to combustion will increase, and the furnace temperature will also decrease. In addition, if the primary air supply amount to the drying stage is reduced, the air pressure from the wind box is weakened even if the amount of air introduced can be reduced. This will not spread, resulting in incomplete combustion and reduced incineration efficiency. In such a state, even if oxygen or oxygen-enriched air is supplied as primary air as described in JP-A-3-244913 mentioned above, it is necessary to blow out a predetermined amount of oxygen or oxygen-enriched air from the drying stage. Instead, it is inherently difficult to reduce the amount of air introduced. Therefore, the effect of reducing the amount of exhaust gas is not sufficient, and the primary air blown from the drying stage is still a factor that prevents the combustion chamber from becoming hot, so a lot of unburned gas is brought into the secondary combustion chamber. As a result, there is a problem that the control of pollutants is not sufficient.
[0008]
The present invention has been made in view of the above circumstances, and can reduce the amount of air introduced and increase the temperature inside the furnace, improve the incineration efficiency of the furnace, and increase the unburned content of the combustible gas. Is provided, and a stoker-type incinerator and an incineration method using the same are provided.
[0009]
[Means for Solving the Problems]
Solve the above issues The present invention The stoker-type incinerator performs drying and pyrolysis while sequentially moving the incinerated product supplied from the garbage supply port into the combustion chamber on a plurality of stoker stages having a wind box below in the combustion chamber. In addition, in the stoker-type incinerator to be further burned, at least for the incinerated product stacked in the drying stage that is the stoker stage that performs the drying and pyrolysis, located near the dust supply port, Measure the static pressure of the wind box, estimate the stack thickness of the incinerated products that are stacked, according to the estimated stack thickness Having an air supply control unit that adjusts the supply amount of air supplied through the wind box to change. First Features. Here, it is desirable that the air supply control unit adjust the air supply amount so as to change, for example, intermittently or periodically.
[0010]
According to this configuration, it is possible to reduce the amount of air introduced and to sufficiently distribute the air to the entire incinerated products stacked in the drying stage. In other words, the amount of air supplied is adjusted so as to change, for example, intermittently or periodically with respect to the incinerated products stacked in the drying stage. As a result, it is possible to sufficiently spread the air throughout the whole to promote drying and to reduce the air supply amount as a whole. That is, incomplete combustion does not occur and the amount of air introduced can be reduced. Therefore, a stoker-type incinerator that reduces the amount of air introduced, raises the temperature inside the furnace, improves the incineration efficiency of the furnace, reduces unburned combustible gas, and reduces the environmental burden is obtained. be able to.
[0011]
The present invention In the stoker-type incinerator, the wind box located below at least one of the stoker stages is divided into a plurality of width directions perpendicular to the moving direction of the incinerated object, and parallel to the moving direction. The air supply control unit adjusts the supply amount of air supplied through each of the divided wind boxes to change. Second Features. Here, it is desirable that the air supply control unit adjusts the supply amount of air supplied to each wind box so as to change, for example, intermittently or periodically.
[0012]
According to this configuration First feature of the stoker-type incinerator of the present invention Compared to the above, the amount of air introduced can be further reduced, and the incineration efficiency of the furnace can be improved. Usually, the incinerated material supplied from the garbage supply port is not necessarily laminated uniformly in the width direction orthogonal to the moving direction of the incinerated material, and the stacking height near the center in the width direction is the highest. Yamagata distribution. For this reason, even if primary air is supplied from the wind box, where the stacking height of the incinerators is high, the air flow resistance is large, so that it is difficult for air to flow in, and conversely the stacking height near the end in the width direction. When the temperature is low, there is a phenomenon that air easily flows in because the air flow resistance is small. As a result, the incinerator near the center in the width direction is likely to be incompletely combusted, and further, primary air that does not contribute to combustion is likely to flow in from near the end in the width direction. However, in order to adjust the supply amount of the air supplied through each wind box divided in the width direction, for example, to change intermittently or periodically, supply according to the stacking height in the width direction, respectively. It becomes possible to optimize the amount of air. Therefore, First feature of the stoker-type incinerator of the present invention Compared to the case, a stoker-type incinerator that can further reduce the amount of air introduced and improve the incineration efficiency of the furnace can be obtained.
[0013]
The present invention The incineration method using the stoker type incinerator is to dry and heat the incinerated material supplied from the garbage supply port into the combustion chamber while sequentially moving it over a plurality of stoker stages having a wind box below in the combustion chamber. An incineration method using a stoker-type incinerator that performs decomposition and further burns, and is incinerated at least in the drying stage that is located near the dust supply port and performs the drying and thermal decomposition. Against Measure the static pressure of the wind box, estimate the stack thickness of the incinerated products that are stacked, according to the estimated stack thickness Adjust the air supply amount to be intermittently changed through the wind box. First Features. Also, The present invention The incineration method using the stoker-type incinerator is 1st characteristic of the incineration method by the stoker type incinerator of this invention The place where the air supply amount is changed intermittently in Second Features.
[0014]
According to these incineration methods, it is possible to reduce the amount of air introduced and to sufficiently distribute the air to the entire incinerated objects stacked in the drying stage. That is, in order to adjust the supply amount of air so that it is intermittently or periodically changed with respect to the incinerators stacked in the drying stage, when the air supply amount is large, the incinerators are stirred to the whole. It is possible to sufficiently distribute the air and to reduce the air supply amount as a whole. That is, incomplete combustion does not occur and the amount of air introduced can be reduced. Therefore, the amount of air introduced can be reduced, the temperature inside the furnace can be increased, the incineration efficiency of the furnace can be improved, the unburned content of combustible gas can be reduced, and the incineration by the stoker-type incinerator can be used to reduce the environmental burden. A method can be provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a view schematically showing a cross section of the stoker-type incinerator 1 in order to explain the stoker-type incinerator 1 according to the present invention.
In FIG. 2, the stoker-type incinerator 1 is provided with a dust supply port 2 and a pusher-type dust transporter 3, followed by a main combustion chamber 7, and a secondary combustion chamber 8 is provided above it. The configuration continues to an exhaust pipe (not shown). The garbage supply port 2 is an open type, and the transportation speed can be controlled by the subsequent garbage transporter 3.
[0016]
The main combustion chamber 7 is installed in a staircase shape with the stocker stages 4, 5, 6 extending downwardly in order from the dust supply port 2. Each stocker means 4, 5, 6 is composed of a total of three stages of a drying stage 4, a combustion stage 5 and a post-combustion stage 6 in order from the side closest to the dust supply port 2. The incinerated material supplied to the front end of each is sequentially transported to the drying stage 4, the combustion stage 5 and the post-combustion stage 6.
[0017]
The upper wall 30 of the main combustion chamber 7 connected to the secondary combustion chamber 8 is directed upward toward the secondary combustion chamber 8 so that the generated pyrolysis gas is easily induced by the secondary combustion chamber 8 and combusted. The main combustion chamber 7 is inclined and covers the main combustion chamber 7. A secondary air inlet 20 for supplying secondary air toward the main combustion chamber 7 is provided at the inlet of the secondary combustion chamber 8. The secondary air supplied from here completely burns the unburned components contained in the combustion gas generated by the combustion in the combustion stage 5 and the post-combustion stage 6 and then exhausts it from an exhaust pipe (not shown).
[0018]
In FIG. 2, the drying stage 4, the combustion stage 5 and the post-combustion stage 6 installed in the main combustion chamber 7 all have wind boxes 4a, 5a, 6a below them, from which primary air is supplied. It has become so. Each of the stocker stages 4, 5, 6 is provided with a movable grate and a fixed grate which are not shown in the figure alternately. By moving the movable grate back and forth in the front-rear direction, dust is supplied. The incinerated material supplied from the mouth 2 can be sequentially transported backward on the drying stage 4, the combustion stage 5 and the post-combustion stage 6 while stirring the incinerated material. The feed speed of the incinerated object by each of the stocker stages 4, 5, and 6 can be arbitrarily controlled by the longitudinal movement speed of the movable grate. Further, a conveyor 29 is connected under each wind box 4a, 5a, 6a through which a ash that falls from a gap between the grate and the like can be collected via a damper 28.
[0019]
Here, a primary air supply mechanism to each of the wind boxes 4a, 5a, 6a corresponding to each of the stocker stages 4, 5, 6 will be described with reference to FIG. In FIG. 1, primary air is supplied to each wind box from a primary air blower (not shown) through a primary air pipe 50. At this time, the pipe 50 is connected to the wind boxes 4a, 5a, 6a by the distribution pipes 50a, 50b, 50c, respectively. Each distribution pipe 50a, 50b, 50c is provided with a control valve 51a, 51b, 51c capable of adjusting the amount of primary air to be supplied. Each control valve is a solenoid valve, and a valve opening command of each solenoid valve is given by the air supply control units 52 and 53, respectively. In the present embodiment, as shown in FIG. 1, the control valve 51a has an air supply control unit 52, and the control valves 51b and 51c have a configuration in which an air supply control unit 53 gives a valve opening command. It has become.
[0020]
In the air supply control part 52, it adjusts so that the supply amount of the air supplied to the wind box 4a may be changed intermittently by giving the opening degree command of the control valve 51a so as to be repeatedly turned on and off.
Also in the air supply control unit 53, as with the air supply control unit 52, the air supplied to the wind boxes 5a and 6a is given by repeatedly giving ON / OFF instructions to the control valves 51b and 51c. The supply amount can be changed intermittently.
Note that both the air control units 52 and 53 may be provided so as to periodically change the opening command of each control valve.
As described above, the stoker-type incinerator 1 according to this embodiment is configured.
[0021]
Next, the incineration process of the incinerated object by the stoker type incinerator 1 having the above-described structure will be described below. First, in FIG. 2, incinerated materials such as municipal waste are supplied onto the drying stage 4 so as to be pushed out by the waste transporter 3 through the waste supply port 2. On the drying stage 4, moisture in the incinerated material evaporates, and ignition is promoted, and partial thermal decomposition is performed. In this drying process, drying is promoted mainly by two types of heat transfer. One is due to the primary air supplied from the wind box 4a. This primary air is supplied in a state heated to a predetermined temperature by an external heating device (not shown). Then, the incinerated material is dried in the process from the drying stage 4 through the incinerated material to the main combustion chamber 7. The other is due to radiant heat radiated from the upper surface wall 30 heated to a high temperature to the surface layer of the incinerated object moving through the drying stage 4.
[0022]
At this time, in FIG. 1, the air supply control unit 52 gives an opening command of the control valve 51a so as to repeat ON and OFF. Here, the on-time and the off-time are given based on a pattern determined in advance according to the supply amount of the incinerated materials. Thus, the supply amount of air supplied to the wind box 4a is adjusted to be changed intermittently. For this reason, while being able to reduce the amount of air introduction, it becomes possible to distribute air enough to the whole to-be-incinerated thing laminated | stacked on a drying stage. That is, in order to adjust the supply amount of air so that it is intermittently changed with respect to the incinerators stacked in the drying stage, when the air supply amount is large, the incinerators are agitated so that the air is fully aired. As a whole, it is possible to reduce the air supply amount. That is, incomplete combustion does not occur and the amount of air introduced can be reduced.
[0023]
Next, the incinerated product that has undergone the drying process is moved to the combustion stage 5. Here, the primary air supplied from the wind box 5a ignites, and the volatile component and the fixed carbon component are combusted.
After that, in the post-combustion stage 6, the unburned portion that has passed without being burned is burned until it becomes completely ash. The pyrolysis gas generated in the combustion chamber 7 is mixed with the secondary air to reach the secondary combustion chamber 8 where it is burned.
In the combustion stage 5 and the post-combustion stage 6 as well, as with the air supply control unit 52, the air supply control unit 53 gives the opening commands of the control valves 51b and 51c to repeat ON and OFF as appropriate. ing.
[0024]
The above is the incineration process of the incineration object by the stoker type incinerator 1 according to the present embodiment. According to this, the amount of air introduced can be reduced, the inside of the furnace can be heated, and the incineration efficiency of the furnace Can be obtained, and a stoker-type incinerator that reduces unburned combustible gas and reduces environmental burden can be obtained. In addition, since the amount of air introduced can be reduced and the combustion exhaust gas can be raised in temperature, the effect of improving the efficiency of a boiler or the like for heating the primary air can also be obtained.
In addition, description of said Example of embodiment serves as description of embodiment of the incineration method by the stoker type incinerator concerning this invention.
[0025]
Further, the embodiment is not limited to the above, and for example, the embodiment may be modified as follows.
[0026]
(1) In this embodiment, as shown in FIG. 1, the primary air is supplied to the wind box 5 a through the distribution pipe 50 b, and the air supply amount is determined by a command from the air supply control unit 53. It is determined by periodically adjusting the valve opening degree of the control valve 51b controlled based on the control valve 51b. However, as shown in another embodiment of FIG. 3, the wind box 5a is divided into a plurality of width directions perpendicular to the moving direction of the incinerated object 54, and arranged in parallel with the moving direction, The air supply control unit 53 may adjust the supply amount of air supplied through each of the divided wind boxes so as to change intermittently or periodically.
In this case, the distribution pipe 50b for supplying primary air to the wind box 5a is further distributed to the pipes 55a, 55b, and 55c, and these pipes are connected to the divided wind boxes 56a, 56b, and 56c, respectively. The pipes 55a, 55b, and 55c are respectively provided with control valves 57a, 57b, and 57c. These control valves are repeatedly turned on and off by the air supply control unit 53, or the air supply amount. Is controlled to increase or decrease periodically. The control of the air supply amount to each divided wind box may be performed in a separate and independent pattern, or may be performed with a mutual dependency. When control is performed with mutual dependency, for example, by sequentially supplying air to the divided wind boxes 56a, 56b, and 56c, an effect of suppressing the pressure fluctuation of the primary air supply system can be obtained. It is done.
[0027]
According to this example of another embodiment, the amount of air introduced can be further reduced and the incineration efficiency of the furnace can be improved as compared with the case of this embodiment. Usually, the incinerated material supplied from the garbage supply port is not necessarily laminated uniformly in the width direction orthogonal to the moving direction of the incinerated material, and the stacking height near the center in the width direction is the highest. Yamagata distribution. For this reason, even if primary air is supplied from the wind box, where the stacking height of the incinerators is high, the air flow resistance is large, so that it is difficult for air to flow in, and conversely the stacking height near the end in the width direction. When the temperature is low, there is a phenomenon that air easily flows in because the air flow resistance is small. As a result, the incinerator near the center in the width direction is likely to be incompletely combusted, and further, primary air that does not contribute to combustion is likely to flow in from near the end in the width direction. However, in order to adjust the supply amount of the air supplied through each wind box divided in the width direction so as to change intermittently or periodically, respectively, according to the stacking height in the width direction, The amount can be optimized.
[0028]
(2) In this embodiment, the supply amount of primary air is adjusted by giving a valve opening degree command to the control valve so as to repeat on and off. However, the present invention is not limited to this example. For example, a valve opening command is given in a sine curve, or a stepwise change is made so that the normal flow rate is significantly reduced periodically. Good. Even in this case, the same effect as the present embodiment can be obtained.
[0029]
(3) In the present embodiment, the valve opening degree is controlled based on a pattern set in advance according to the supply amount of the incinerated material. However, the present embodiment may not necessarily be the same as the embodiment, for example, by measuring the static pressure of the wind box, estimating the stacking thickness of the incinerated products stacked, and according to this, the air supply amount It may be one having a configuration for adjusting the valve opening so as to intermittently change.
[0030]
(4) In another embodiment of FIG. 3, the structure of the wind box 5a of the combustion stage 5 is shown divided into a plurality of parts in the width direction, but this structure is not necessarily applied to the wind box 5a. It may not be a thing, and may be applied to the wind box 4a of the drying stage 4 or the wind box 6a of the post-combustion stage 6.
[0031]
(5) In FIG. 1 and FIG. 2, the stoker type incinerator has been described in which the stoker steps are stepped down step by step. However, even if the stoker steps are of a type in which each stoker step is horizontally disposed, The apparatus and method of the invention can be applied.
[0032]
(6) In FIG. 1 to FIG. 3, examples of each stoker-stage wind box include one each arranged one by one or one arranged in parallel, but a plurality of, for example, two wind boxes are used. It may be arranged in series. The apparatus and method of the present invention can also be applied to a stoker-type incinerator of the type in which the combustion stage 5 and the post-combustion stage 6 are integrated.
[0033]
【The invention's effect】
As explained above, First feature of the stoker-type incinerator of the present invention According to this, it is possible to reduce the amount of air introduced and to sufficiently distribute the air to the entire incinerated products stacked in the drying stage. In other words, the amount of air supplied is adjusted so as to change, for example, intermittently or periodically with respect to the incinerated products stacked in the drying stage. As a result, it is possible to sufficiently spread the air throughout the whole to promote drying and to reduce the air supply amount as a whole. That is, incomplete combustion does not occur and the amount of air introduced can be reduced. Therefore, a stoker-type incinerator that reduces the amount of air introduced, raises the temperature inside the furnace, improves the incineration efficiency of the furnace, reduces unburned combustible gas, and reduces the environmental burden is obtained. be able to.
[0034]
Second feature of the stoker-type incinerator of the present invention according to, First feature of the stoker-type incinerator of the present invention Compared to the above, the amount of air introduced can be further reduced, and the incineration efficiency of the furnace can be improved. Usually, the incinerated material supplied from the garbage supply port is not necessarily laminated uniformly in the width direction orthogonal to the moving direction of the incinerated material, and the stacking height near the center in the width direction is the highest. Yamagata distribution. For this reason, even if primary air is supplied from the wind box, where the stacking height of the incinerators is high, the air flow resistance is large, so that it is difficult for air to flow in, and conversely the stacking height near the end in the width direction. When the temperature is low, there is a phenomenon that air easily flows in because the air flow resistance is small. As a result, the incinerator near the center in the width direction is likely to be incompletely combusted, and further, primary air that does not contribute to combustion is likely to flow in from near the end in the width direction. However, in order to adjust the supply amount of the air supplied through each wind box divided in the width direction, for example, to change intermittently or periodically, supply according to the stacking height in the width direction, respectively. It becomes possible to optimize the amount of air. Therefore, compared with the case of Claim 1, the stoker type incinerator which can further reduce the air introduction amount and improve the incineration efficiency of the furnace can be obtained.
[0035]
1st characteristic or 2nd characteristic of the incineration method by the stoker type incinerator of this invention According to this, it is possible to reduce the amount of air introduced and to sufficiently distribute the air to the entire incinerated products stacked in the drying stage. That is, in order to adjust the supply amount of air so that it is intermittently or periodically changed with respect to the incinerators stacked in the drying stage, when the air supply amount is large, the incinerators are stirred and As a result, the air supply amount can be reduced as a whole. That is, incomplete combustion does not occur and the amount of air introduced can be reduced. Therefore, the amount of air introduced can be reduced, the temperature inside the furnace can be raised, the incineration efficiency of the furnace can be improved, the unburned content of combustible gas can be reduced, and the incineration by the stoker-type incinerator that reduces the environmental burden A method can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an air supply system in a stoker-type incinerator according to the present invention.
FIG. 2 is a view schematically showing a cross section of a side surface of a stoker-type incinerator according to the present invention.
FIG. 3 is a diagram showing another embodiment of the stoker-type incinerator according to the present invention.
[Explanation of symbols]
1 Stoker-type incinerator
2 Garbage supply port
4 Drying stage
5 Combustion stage
6 Post combustion stage
4a, 5a, 6a wind box
50 Piping for primary air supply
50a, 50b, 50c Distribution piping
51a, 51b, 51c Control valve
52, 53 Air supply control unit

Claims (1)

Stoker-type incineration in which the incinerated product supplied from the garbage supply port is dried and pyrolyzed while being sequentially moved on a plurality of stoker stages having a wind box below in the combustion chamber, and further combusted In the furnace,
At least, the static pressure of the wind box is measured and stacked on the incineration object stacked on the drying stage, which is the stoker stage that performs drying and thermal decomposition, located near the dust supply port. wherein estimating the stacked thickness of the object to be incinerated, have a air supply control unit to be adjusted to vary the supply amount of the air supplied through the air box in accordance with the lamination thickness was estimated,
The wind box located below at least one of the stalker stages is divided into a plurality of width directions perpendicular to the moving direction of the incinerated object and arranged in parallel with the moving direction. The air supply control unit changes the supply amount of air supplied through each of the divided wind boxes and adjusts the air to be sequentially supplied to the divided wind boxes in the width direction. A stoker-type incinerator characterized by that.

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