Incineration ash circulation system

Abstract

To provide an incinerated ash circulation system which inhibits increase of manufacturing costs of a stoker type incinerator and achieves long life of a fire grate.SOLUTION: One example of an incinerated ash circulation system according to an embodiment of the disclosure includes: a stoker type incinerator 2 having a combustion chamber 2A into which an incinerated object is placed through an inlet 21a, and a fire grate 24 disposed in the combustion chamber 2A; and an incinerated ash return device AS1 which returns incinerated ash discharged from the stoker type incinerator 2 to the stoker type incinerator 2 based on a weight of the incinerated object placed into the inlet 21a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a circulation system for incineration ash discharged from a stoker-type incinerator. [Background technology]

[0002] Conventionally, stoker-type incinerators have been widely used in waste treatment plants that incinerate municipal waste, industrial waste, etc. These incinerators are often equipped with boilers for heat recovery. The steam generated in the boiler is often supplied to a steam turbine generator and used to generate electricity.

[0003] Furthermore, in recent years, from the perspective of effective utilization of waste energy, there has been an increase in the use of waste fuels such as RPF and biomass, which are made primarily from waste plastics, as fuel for stoker-type incinerators and for power generation, etc. However, waste fuels such as RPF and biomass have a high calorific value, and the temperature inside the incinerator becomes extremely high, which causes the temperature of the grates to also become high, causing rapid deterioration and raising concerns about a shortened lifespan of the grates.

[0004] At the waste disposal site mentioned above, when incinerating waste that contains a lot of plastic and other high-heat-generating materials, the temperature inside the incinerator becomes extremely high, and there is a similar risk of the lifespan of the fire grates being shortened.

[0005] Patent Document 1 proposes a water-cooled fire grate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-4220 Summary of the Invention [Problem to be solved by the invention]

[0007] The water-cooled fire grate described in Patent Document 1 can prevent the shortening of life due to high-temperature deterioration, but the incorporation of a water-cooling structure inevitably increases manufacturing costs, which leads to a problem that the increase in manufacturing costs of the fire grate also leads to an increase in manufacturing costs of the incinerator.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an incineration ash circulation system that can suppress increases in manufacturing costs of stoker-type incinerators and extend the life of grates. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, an incineration ash circulation system according to one aspect of the present disclosure comprises a stoker-type incinerator having a combustion chamber into which combustible materials are fed through an inlet and a fire grate disposed within the combustion chamber, and an incineration ash return device that returns incineration ash discharged from the stoker-type incinerator to the stoker-type incinerator based on the weight of the combustible materials fed into the inlet. [Effects of the Invention]

[0010] The present disclosure has the above-described configuration and has the effect of providing an incineration ash circulation system that can suppress increases in manufacturing costs of stoker-type incinerators and extend the life of grates. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an example of an incineration ash circulation system according to this embodiment. [Figure 2] FIG. 2 is a diagram showing a schematic configuration of another example of the incineration ash circulation system of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Note that the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant explanations will be omitted. Furthermore, the drawings are schematic representations of the respective components for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted.

[0013] (Embodiment) FIG. 1 is a diagram showing a schematic configuration of an example of an incineration ash circulation system according to this embodiment.

[0014] The incineration ash circulation system of this embodiment includes a stoker-type incinerator 2 and an incineration ash return device AS1. The incineration ash return device AS1 includes a weight measuring device Ws provided on a crane 1, a falling ash conveyor 3, an incineration ash transport device 4, a discharge switching device 5, a return device 6, an ash pit 7, and a controller 11.

[0015] The stoker-type incinerator 2 has a combustion chamber 2A, a hopper 21, a feeder 22, multiple stokers 23 (23a, 23b, 23c), and a bottom ash discharge chute 25. Primary air is supplied to the combustion chamber 2A from below through each of the stokers 23a, 23b, 23c. Secondary air is also supplied from predetermined air supply ports provided on the wall of the combustion chamber 2A.

[0016] The stoker-type incinerator 2 may be used, for example, in a power generation facility or the like, and may be an incinerator that burns waste-derived fuels such as RPF (Refuse Derived Paper and Plastics Densified Fuel), RDF (Refuse Derived Fuel), biomass, etc. The stoker-type incinerator 2 may also be an incinerator that burns municipal waste or industrial waste. Therefore, examples of materials to be combusted in the stoker-type incinerator 2 include waste-derived fuels such as RPF, RDF, biomass, municipal waste, industrial waste, etc. The fuel stoker-type incinerator 2 may also use a mixture of the above fuels as the material to be combusted.

[0017] In this stoker-type incinerator 2, materials to be combusted are appropriately thrown into the hopper 21 from the inlet 21a by, for example, a crane 1. The crane 1 is, for example, an overhead crane with a bucket. The crane 1 is configured to lift the materials to be combusted from a temporary storage location for the materials to be combusted, such as a garbage pit, and throw them into the hopper 21, either automatically or manually. A weight measuring device Ws is installed on the crane 1. The weight measuring device Ws measures the weight of the materials to be combusted that the crane 1 throws into the inlet 21a of the hopper 21, and transmits the measured weight to the controller 11. The inlet 21a of the hopper 21 is the inlet of the stoker-type incinerator 2.

[0018] Materials to be combusted, appropriately fed into the inlet 21a by the crane 1, are temporarily stored in the hopper 21 and then pushed out from the entrance of the combustion chamber 2A onto the drying stoker 23a by, for example, a pusher-type feeder 22. The materials to be combusted dry and ignite as they are transported by the drying stoker 23a. The ignited materials to be combusted are burned on the combustion stoker 23b, and the remaining unburned materials are burned as they are transported by the post-combustion stoker 23c, and the bottom ash remaining after combustion is discharged from the discharge chute 25 to the incineration ash transport device 4.

[0019] As is well known, the stoker 23 has fixed grates 24a and movable grates 24b arranged alternately, and the movable grates 24b move back and forth in the direction indicated by the arrows, thereby transporting the material to be burned on the grates 24 toward the discharge chute 25. A plurality of fixed grates 24a and movable grates 24b are arranged side by side in the furnace width direction, which is the depth direction of the paper in Figure 1.

[0020] The stoker-type incinerator 2 described above is an example, and various other known stoker-type incinerators can be used. Specifically, the number of stokers 23 is not limited to three. The installation angle of the stokers 23 may also be changed. Furthermore, the hopper 21 may be configured so that the material to be combusted input from the input port 21a automatically enters the combustion chamber 2A without being provided with the supply device 22.

[0021] Furthermore, in the above description, the crane 1 is used as an example of a means for supplying the combustible material to the hopper 21, but the present invention is not limited to this and may be any means capable of supplying the combustible material to the hopper 21. For example, a weighing conveyor equipped with a weight measuring device such as a load cell for measuring the weight of the material being conveyed may be used. In this case, the weight measuring device of the weighing conveyor transmits the measured weight of the combustible material to the controller 11.

[0022] The falling ash from each stoker 23 is transported by the falling ash conveyor 3 and discharged to the incineration ash transporting device 4. In other words, the incineration ash, which includes the main ash discharged from the discharge chute 25 and the falling ash from the stoker 23, is transported by the incineration ash transporting device 4. The falling ash from each stoker 23 may be transported to a location different from the incineration ash transporting device 4.

[0023] The incineration ash transport device 4 may be, for example, a scraper conveyor. Alternatively, it may be a conveyor with water filled in the trough of a scraper conveyor. Alternatively, the incineration ash transport device 4 may be, for example, a dry conveyor. Alternatively, an ash extrusion device may be used instead of the incineration ash transport device 4. This ash extrusion device is a known device equipped with a water tank and a device below the water tank that extrudes ash to the outside.

[0024] The incineration ash transported by the incineration ash transport device 4 is supplied to the discharge switching device 5. The discharge switching device 5 switches the discharge direction between a first direction and a second direction to discharge the supplied incineration ash. The discharge switching device 5 can be configured, for example, by a branch damper that switches the discharge direction between two directions by driving a cylinder or a motor.

[0025] Here, when the discharge switching device 5 is set to the first direction, the incineration ash is discharged to the return device 6, and when the discharge direction is set to the second direction, the incineration ash is discharged to the ash pit 7. The return device 6 is a device that transports the incineration ash supplied from the discharge switching device 5 to the stoker-type incinerator 2, and can be configured using a bucket conveyor or the like. The incineration ash returned by this return device 6 is supplied to the inlet 21a of the hopper 21. Note that the incineration ash returned by the return device 6 may also be supplied to the combustion chamber 2A from a specified supply port provided on the wall surface of the combustion chamber 2A without going through the hopper 21.

[0026] The controller 11 has a CPU, memory, etc., and controls the stoker-type incinerator 2 and the incineration ash return device AS1. Specifically, the controller 11 controls the supply device 22, the drive device for the movable grate 24b, the incineration ash transport device 4, the discharge switching device 5, and the return device 6. The controller 11 may be configured as a single controller that performs centralized control, or may be configured as a plurality of controllers that cooperate with each other to perform decentralized control.

[0027] In this incineration ash return device AS1, the controller 11 switches the discharge direction of the discharge switching device 5, so that a portion of the incineration ash discharged from the stoker-type incinerator 2 is returned to the stoker-type incinerator 2, and the remainder is discharged to the ash pit.

[0028] Next, the operation of the incineration ash return device AS1 will be explained. Here, during operation of the stoker-type incinerator 2, the falling ash conveyor 3, the incineration ash transport device 4, and the return device 6 are each operated at a predetermined transport speed. Below, we will mainly explain an example of a method for switching the discharge direction of the discharge switching device 5 by the controller 11.

[0029] For example, when the combustible material is removed from a pit where it is stored by a crane 1 and placed into a hopper 21, the weight of the removed combustible material is measured by a weight measuring device Ws, and the measured weight W1 is transmitted to the controller 11.

[0030] The controller 11 calculates the required time t1 required for the material to pass over the grate 24 by a weight equivalent to the measured weight W1 of the material measured by the weight measuring device Ws. Here, for example, the speed at which the material is supplied to the drying stoker 23a by the supply device 22 and the speed at which the movable grate 24b in each stoker 23a, 23b, and 23c moves back and forth are constant, and the time ta required for a predetermined weight Wa of material to pass over the grate 24 is determined in advance. The required time t1 may be calculated using the measured weight W1 as t1 = ta × W1 / Wa. Note that instead of the predetermined values ta and Wa, a value tb of ta / Wa may be determined in advance, and the required time t1 may be calculated as t1 = tb × W1.

[0031] Furthermore, the controller 11 calculates the return time t2, which is the time required for the discharge direction of the discharge switching device 5 to be the first direction, that is, the direction of the return device 6, based on the measured weight W1 of the combustible material. The return time t2 is shorter than the required time t1. Here, the weight W2 of the incineration ash returned to the stoker-type incinerator 2 during the return time t2 is determined as k times the measured weight W1. In other words, W2 = k × W1. k is a predetermined value within the range of 0.01 to 0.20, for example.

[0032] To summarize the above explanation, of the incineration ash discharged from the stoker-type incinerator 2 within the time t1 during which the combustible material with a weight of W1 passes over the grate 24 and burns, the incineration ash with a weight of W2 is supplied to the return device 6 and returned to the stoker-type incinerator 2. Here, the time during which the discharge direction of the discharge switching device 5 is changed to the direction of the return device 6 in order to supply the incineration ash with a weight of W2 to the return device 6 is the return time t2.

[0033] It has been found through experiments that the heat load on the grate 24 can be reduced by approximately 90% by depositing a predetermined thickness of incineration ash, for example, several millimeters to 10 mm, on the grate 24. Therefore, when combustible material with a measured weight W1 is charged into the hopper 21, in order to deposit a predetermined thickness of incineration ash on the grate 24, it is decided that incineration ash with a weight of k × W1 is returned and charged into the hopper 21.

[0034] Furthermore, the weight per unit time of the incineration ash discharged from the stoker-type incinerator 2 is set to a predetermined value Wt. This predetermined value Wt may be an experimental value or a statistical value. The conveying speed of the incineration ash conveying device 4 is set so that the incineration ash discharged from the stoker-type incinerator 2 is smoothly supplied to the discharge switching device 5. Therefore, the weight per unit time of the incineration ash supplied from the incineration ash conveying device 4 to the discharge switching device 5 is also set to the predetermined value Wt, and the return time t2 when the discharge direction of the discharge switching device 5 is the direction of the return device 6 can be calculated by the following formula.

[0035] t2=W2 / Wt=k×W1 / Wt The memory of the controller 11 stores in advance the formulas for calculating the required time t1 and the return time t2, as well as the predetermined values ta, Wa, k, Wt, etc. included therein.

[0036] In addition, in this example, the conveying speed of the return device 6 is determined so that the incineration ash supplied to the return device 6 within the return time t2, which is shorter than the required time t1, is dumped from the return device 6 into the hopper 21 within the same time as the required time t1, and the return device 6 operates at a constant conveying speed.

[0037] In the above description, the supply rate of the material to be combusted by the supply device 22 to the drying stoker 23a and the speed at which the movable grate 24b in each of the stokers 23a, 23b, and 23c moves back and forth are constant, i.e., the passing speed of the material to be combusted is constant on the stoker 23. If the passing speed of the material to be combusted on the stoker 23 varies, i.e., if the supply rate of the supply device 22 and the speed at which the movable grate 24b in each of the stokers 23a, 23b, and 23c moves back and forth are changed, formulas for calculating the required time t1 and the return time t2 may be prepared in advance using the supply rate and the speed at which the movable grate 24b moves back and forth as variables, and the required time t1 and the return time t2 may be calculated.

[0038] Then, based on the calculated required time t1 and return time t2, the controller 11 switches the discharge direction of the discharge switching device 5 so that the time during which the discharge direction of the discharge switching device 5 is toward the return device 6 within the required time t1 coincides with the return time t2. For example, after receiving the measured weight W1 of the combustible material thrown from the crane 1 from the weight measuring device Ws, the controller 11 switches the discharge direction of the discharge switching device 5 toward the return device 6 at a predetermined timing. After that, when the same time as the return time t2 has elapsed, the discharge direction of the discharge switching device 5 is switched to the direction of the ash pit 7. In this example, the discharge direction of the discharge switching device 5 is continuously set to the direction of the return device 6 during the return time t2, but this is not limited to this. For example, the discharge direction of the discharge switching device 5 may be intermittently set to the direction of the return device 6 within the required time t1 from the predetermined timing, so that the total time during which the discharge direction is in the direction of the return device 6 coincides with the return time t2.

[0039] As described above, the controller 11 calculates the return time t2 based on the measured weight W1 of the combustible material put into the input port 21a, and performs first control to switch the discharge direction of the discharge switching device 5 so that the time during which the discharge direction of the discharge switching device 5 is set to the direction of the return device 6 within the aforementioned required time t1 coincides with the return time t2. Note that while the discharge direction of the discharge switching device 5 is not set to the first direction, the direction of the return device 6, the discharge direction of the discharge switching device 5 is the second direction, the direction of the ash pit 7. Therefore, when the discharge direction of the discharge switching device 5 is set to the first direction, the discharge destination of the combustible material is the return device 6, and when the discharge direction of the discharge switching device 5 is set to the second direction, the discharge destination of the combustible material is a facility other than the return device 6, such as the ash pit 7.

[0040] As described above, by the controller 11 performing the first control, a predetermined percentage of the incineration ash discharged from the stoker-type incinerator 2 is returned to the stoker-type incinerator 2. The incineration ash sequentially returned by the return device 6 is deposited on the surface of the grate 24, suppressing an increase in the temperature of the grate 24. Therefore, the life of the grate 24 can be extended without using a water-cooled grate, which is expensive to manufacture. Furthermore, by not using a water-cooled grate, an increase in the manufacturing cost of the stoker-type incinerator 2 can be suppressed. Furthermore, there is no possibility of water leakage, which would occur if a water-cooled grate were used.

[0041] Furthermore, the controller 11 may be configured to perform the following second control. In this case, for example, the grate 24 of the combustion stoker 23b is provided with a temperature sensor Ts that detects the surface temperature of the grate 24, and the temperature detected by the temperature sensor Ts is transmitted to the controller 11. The temperature sensor Ts can be configured, for example, by a thermocouple or the like.

[0042] Then, when the detected temperature of the temperature sensor Ts becomes equal to or higher than the first reference temperature while the discharge direction of the discharge switching device 5 is set to the second direction, that is, the direction toward the ash pit 7, by the first control, the controller 11 stops the first control and performs a second control to switch the discharge direction of the discharge switching device 5 to the first direction, that is, the direction toward the return device 6.

[0043] By this second control, when the surface temperature of the grate 24 becomes high, equal to or higher than the first reference temperature, the discharge direction of the discharge switching device 5 is changed so that the incineration ash is returned to the stoker-type incinerator 2. This shortens the time that the surface temperature of the grate 24 remains high, and suppresses the progression of deterioration of the grate 24. Note that after the discharge direction of the discharge switching device 5 is switched to the direction of the return device 6 by the second control, the first control may be resumed when the temperature detected by the temperature sensor Ts becomes lower than the first reference temperature.

[0044] Furthermore, the controller 11 may be configured to perform the following third control: In this case, when the discharge direction of the discharge switching device 5 is set to the first direction, toward the return device 6, by either the first control or the second control, and the temperature detected by the temperature sensor Ts becomes equal to or lower than a second reference temperature that is lower than the first reference temperature, the controller 11 performs the third control to stop one of the above controls and switch the discharge direction of the discharge switching device 5 to the second direction, toward the ash pit 7.

[0045] By this third control, when the surface temperature of the grate 24 becomes a low temperature equal to or lower than the second reference temperature, the discharge direction of the discharge switching device 5 is changed to the direction of the ash pit 7 so that the incineration ash is not returned to the stoker-type incinerator 2. This makes it possible to suppress a decrease in combustion efficiency within the stoker-type incinerator 2. Note that after the discharge direction of the discharge switching device 5 is switched to the direction of the ash pit 7 by the third control, if the temperature detected by the temperature sensor Ts exceeds the second reference temperature, the first control may be resumed.

[0046] FIG. 2 is a diagram showing a schematic configuration of another example of the incineration ash circulation system of this embodiment. The incineration ash circulation system shown in Figure 2 differs from the incineration ash circulation system shown in Figure 1 in that a magnetic separator 8 is provided between the incineration ash conveying device 4 and the discharge switching device 5 in the incineration ash return device AS2. In this case, the incineration ash discharged from the incineration ash conveying device 4 has had magnetic matter such as iron removed by the magnetic separator 8, and the resulting incineration ash is supplied to the discharge switching device 5. In addition, the magnetic matter such as iron removed by the magnetic separator 8 is transported to an iron container 10 by an iron conveyor 9.

[0047] In the incineration ash circulation system shown in Figure 2, similar effects can be obtained by the controller 11 performing the first control described above, as in the incineration ash circulation system shown in Figure 1. Furthermore, similar effects can be obtained by the controller 11 performing the second control described above. Furthermore, similar effects can be obtained by the controller 11 performing the third control described above.

[0048] From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present disclosure.

[0049] (summary) An incineration ash circulation system according to one aspect of the present disclosure includes a stoker-type incinerator having a combustion chamber into which combustible materials are fed through an inlet and a fire grate disposed within the combustion chamber, and an incineration ash return device that returns incineration ash discharged from the stoker-type incinerator to the stoker-type incinerator based on the weight of the combustible materials fed into the inlet.

[0050] With this configuration, the incineration ash returned to the stoker-type incinerator is deposited on the surface of the grate, suppressing the rise in the temperature of the grate. Therefore, the life of the grate can be extended without using a water-cooled grate, which is expensive to manufacture. Furthermore, by not using a water-cooled grate, the increase in manufacturing costs of the stoker-type incinerator can be suppressed. Furthermore, there is no possibility of water leakage, which occurs when a water-cooled grate is used.

[0051] The incineration ash return device comprises a discharge switching device to which the incineration ash discharged from the stoker-type incinerator is supplied and which switches the discharge direction between a first direction and a second direction to discharge the supplied incineration ash, a return device to which the incineration ash discharged from the discharge switching device is supplied when the discharge direction of the discharge switching device is the first direction and which returns the supplied incineration ash to the stoker-type incinerator, and a controller that switches the discharge direction of the discharge switching device, and the controller may perform first control to control the time for which the discharge direction of the discharge switching device is in the first direction based on the weight of the combustible material fed into the inlet of the stoker-type incinerator.

[0052] According to this configuration, when the controller performs the first control, a predetermined percentage of the incineration ash discharged from the stoker-type incinerator is returned to the stoker-type incinerator. The returned incineration ash accumulates on the surface of the grate, suppressing the rise in the grate temperature. Therefore, the life of the grate can be extended without using a water-cooled grate, which is expensive to manufacture. Furthermore, by not using a water-cooled grate, the manufacturing cost of the stoker-type incinerator can be suppressed.

[0053] In addition, the first control may be a control that calculates a return time, which is the time it takes for the discharge direction of the emission switching device to be in the first direction, based on the weight of the combustible material fed into the inlet of the stoker-type incinerator, and switches the discharge direction of the emission switching device so that the time it takes for the discharge direction of the emission switching device to be in the first direction matches the return time within the time it takes for the combustible material equivalent to the weight used to calculate the return time to pass over the grate.

[0054] The stoker-type incinerator may further include a temperature sensor that detects the surface temperature of the grate, and the controller may be configured to perform second control to stop the first control and switch the discharge direction of the discharge switching device to the first direction when the temperature detected by the temperature sensor becomes equal to or higher than a first reference temperature while the discharge direction of the discharge switching device is set to the second direction under the first control. By this second control, when the surface temperature of the grate becomes high enough to be equal to or higher than the first reference temperature, the discharge direction of the discharge switching device is changed to the first direction so that the incineration ash is returned to the stoker-type incinerator. This shortens the time the surface temperature of the grate remains high, and suppresses the progression of grate deterioration.

[0055] The controller may be configured to perform a third control to stop one of the first and second controls and switch the discharge direction of the discharge switching device to the second direction when the temperature detected by the temperature sensor falls below a second reference temperature that is lower than the first reference temperature while the discharge direction of the discharge switching device is set to the first direction by either the first control or the second control. By this third control, when the surface temperature of the grate falls below the second reference temperature, the discharge direction of the discharge switching device is changed to the second direction so that the incineration ash is not returned to the stoker-type incinerator. This can suppress a decrease in combustion efficiency in the stoker-type incinerator.

[0056] The return device may be configured to feed the returned incineration ash into the inlet of the stoker-type incinerator. [Explanation of symbols]

[0057] AS1, AS2 Incineration ash return device 2. Stoker-type incinerator 2A combustion chamber 5. Emission switching device 6 Return device 11 Controller 21a Inlet 24 Grate Ws Weight Measuring Instrument Ts temperature sensor

Claims

1. a stoker-type incinerator having a combustion chamber into which materials to be burned are fed through an inlet and a fire grate disposed within the combustion chamber; an incineration ash return device that returns to the stoker-type incinerator incineration ash that is a predetermined percentage of the weight of the combustible material that is input into the input port, out of the incineration ash discharged from the stoker-type incinerator; An incineration ash circulation system equipped with the above.

2. The incineration ash return device is A discharge switching device to which the incineration ash discharged from the stoker-type incinerator is supplied and which switches the discharge direction between a first direction and a second direction to discharge the incineration ash supplied; A return device to which the incineration ash discharged from the discharge switching device is supplied when the discharge direction of the discharge switching device is the first direction, and which returns the supplied incineration ash to the stoker-type incinerator; a controller for switching the discharge direction of the discharge switching device; The controller A first control is performed to control the time during which the discharge direction of the discharge switching device is in the first direction based on the weight of the combustible material fed into the feed port of the stoker-type incinerator. The incineration ash circulation system according to claim 1.

3. The stoker-type incinerator further includes a temperature sensor for detecting the surface temperature of the grate, The controller When the temperature detected by the temperature sensor becomes equal to or higher than a first reference temperature while the discharge direction of the discharge switching device is set to the second direction by the first control, the first control is stopped and a second control is performed to switch the discharge direction of the discharge switching device to the first direction. The incineration ash circulation system according to claim 2.

4. The controller When the temperature detected by the temperature sensor becomes equal to or lower than a second reference temperature that is lower than the first reference temperature while the discharge direction of the discharge switching device is set to the first direction by one of the first control and the second control, a third control is performed to stop one of the first control and switch the discharge direction of the discharge switching device to the second direction. The incineration ash circulation system according to claim 3.

5. The incineration ash return device is configured to feed the incineration ash to be returned into the inlet of the stoker-type incinerator, The incineration ash circulation system according to any one of claims 1 to 4.

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