Combustion control method and combustion control device for refuse incinerator

Abstract

To provide a combustion control method that enables stable combustion in a stoker type refuse incinerator.SOLUTION: A combustion control method includes processes of: determining whether a temperature of a secondary combustion chamber 5 is on a high temperature side or a low temperature side of a first set value; and setting a recirculation gas rate to a first target value when the temperature of the secondary combustion chamber 5 is on the high temperature side of the first set value and setting the recirculation gas rate to a second target value when the temperature of the secondary combustion chamber 5 is on the low temperature side of the first set value. Here, the first target value is larger than the second target value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combustion control method and a combustion control device for a garbage incinerator.

Background Art

[0002] The following Patent Documents 1 and 2 describe a stoker-type (grate-type) garbage incinerator.

[0003] In the garbage incinerator of the following Patent Document 1, the amount of secondary combustion air is adjusted based on the gas temperature in the primary combustion chamber and the gas temperature in the secondary combustion chamber, etc., thereby achieving combustion stabilization.

[0004] In the garbage incinerator of the following Patent Document 2, the temperature of the secondary combustion chamber is stabilized by controlling the flow rate of the exhaust gas (recirculated exhaust gas) that is discharged from the secondary combustion region and then returned to the secondary combustion region.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the technology of Patent Document 1, since the secondary combustion air is introduced from the outside of the incinerator, depending on the amount of the introduced secondary combustion air, the amount of exhaust gas may vary greatly. Then, there may be a shortage of the equipment capacity for removing harmful substances in the exhaust gas, and there is a possibility that the plant operation becomes difficult.

[0007] In the technology of Patent Document 2, since the flow rate of the circulating exhaust gas is controlled, the amount of exhaust gas may vary significantly depending on that flow rate. Therefore, similar to the technology of Patent Document 1, there is a risk that plant operation will become difficult.

[0008] The present invention has been made in view of the above-described situation. The main object of the present invention is to provide a technology for realizing stable combustion without significantly varying the amount of exhaust gas in a stoker-type garbage incinerator.

Means for Solving the Problems

[0009] The present invention can be expressed as an invention described in the following items.

[0010] (Item 1) A combustion control method for a garbage incinerator having a forced draft fan, a dust feeder, a drying stoker, a combustion stoker, a post-combustion stoker, a primary combustion chamber, and a secondary combustion chamber, The combustion air sent from the forced draft fan is divided into primary air and secondary air, The primary air is further divided and supplied to the drying stoker, the combustion stoker, and the post-combustion stoker, The secondary air is supplied to the secondary combustion chamber, A step of determining whether the temperature of the secondary combustion chamber is higher or lower than a first set value, When the temperature of the secondary combustion chamber is higher than the first set value, setting the recirculation gas ratio to a first target value, and when the temperature of the secondary combustion chamber is lower than the first set value, setting the recirculation gas ratio to a second target value, Here, the recirculation gas ratio is the ratio of the exhaust gas returned to the secondary combustion chamber among the exhaust gas discharged downstream from the secondary combustion chamber, The first target value is set to a value larger than the second target value A combustion control method for a garbage incinerator.

[0011] (Item 2) Furthermore, the garbage incinerator has a denitration reaction tower for detoxifying nitrogen oxides in the exhaust gas discharged from the downstream side of the secondary combustion chamber, a step of determining whether the temperature of the denitration reaction tower is higher or lower than a second set value, when the temperature of the denitration reaction tower is higher than the second set value, setting the recirculation gas ratio to a third target value, and when the temperature of the denitration reaction tower is lower than the second set value, setting the recirculation gas ratio to a fourth target value, further comprising a step of comparing the target values set in each of the above steps among the first to fourth target values, and adjusting the recirculation gas ratio using the larger target value as the actual target value, the fourth target value is set to be larger than the third target value The combustion control method of the garbage incinerator according to Item 1.

[0012] (Item 3) The fourth target value is set to be larger than the first target value The combustion control method of the garbage incinerator according to Item 2.

[0013] (Item 4) A combustion control device for a garbage incinerator having a forced air blower, a dust feeder, a drying stoker, a combustion stoker, a post-combustion stoker, a primary combustion chamber, a secondary combustion chamber, and a treatment unit, further comprising a secondary combustion chamber thermometer for measuring the temperature of the secondary combustion chamber, the combustion air sent from the forced air blower is distributed into primary air and secondary air, the primary air is further distributed and supplied to the drying stoker, the combustion stoker, and the post-combustion stoker, the secondary air is supplied to the secondary combustion chamber, The processing unit determines whether the temperature of the secondary combustion chamber measured by the secondary combustion chamber thermometer is higher or lower than a first set value, and when the temperature of the secondary combustion chamber is higher than the first set value, sets the recirculation gas rate to a first target value, and when the temperature of the secondary combustion chamber is lower than the first set value, performs a process of setting the recirculation gas rate to a second target value, Here, the recirculation gas rate is the ratio of the exhaust gas returned to the secondary combustion chamber among the exhaust gas discharged downstream from the secondary combustion chamber, The first target value is set to a value larger than the second target value. A combustion control device for a garbage incinerator.

Advantages of the Invention

[0014] According to the technology of the present invention, in a stoker-type garbage incinerator, it becomes possible to realize stable combustion without significantly fluctuating the amount of exhaust gas.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0016] Hereinafter, a stoker-type garbage incinerator (hereinafter sometimes referred to as "garbage incinerator" or "incinerator") according to an embodiment of the present invention will be described with reference to the accompanying drawings. Note that FIG. 1 is a schematic explanatory drawing, and the dimensional ratios and scales are not accurate.

[0017] (Configuration of the garbage incinerator of this embodiment) The garbage incinerator of this embodiment has a feeding device 1, a drying stoker 2, a combustion stoker 3, a primary combustion chamber 4, and a secondary combustion chamber 5 (see FIG. 1). Further, this garbage incinerator has a post-combustion stoker 6, a garbage input hopper 7, a processing unit 8 (see FIG. 2), and a forced draft fan 9. The feeding device 1, the drying stoker 2, the combustion stoker 3, and the post-combustion stoker 6 are configured to operate periodically (that is, at a predetermined cycle) according to a command from the processing unit 8. Here, the processing unit 8 acquires the actual garbage input amount to the feeding device 1 through input from the user or an appropriate detection device (not shown), and based on this garbage input amount, determines the operation cycles of the feeding device 1, the drying stoker 2, the combustion stoker 3, and the post-combustion stoker 6. Specifically, if the actual garbage input amount to the feeding device 1 is excessive compared to the target value, the operation cycle is lengthened, and if the actual garbage input amount is too small compared to the target value, the operation cycle is shortened.

[0018] Furthermore, the garbage incinerator of this embodiment has a primary combustion chamber thermometer 41 for measuring the temperature inside the primary combustion chamber 4, a secondary combustion chamber thermometer 51 for measuring the temperature inside the secondary combustion chamber 5, an oxygen concentration meter 52 for measuring the oxygen concentration of the exhaust gas inside the secondary combustion chamber 5, a carbon monoxide concentration meter 53 for measuring the carbon monoxide concentration of the exhaust gas inside the secondary combustion chamber 5, and a denitration reaction tower thermometer 131 (described later) for measuring the temperature of the denitration reaction tower 13.

[0019] (Feeding device) The feeding device 1 can push the garbage input from the garbage input hopper 7 toward the drying stoker 2 at a predetermined cycle, so that the garbage can be supplied to the upper part of the drying stoker 2. For example, garbage is input into the garbage input hopper 7 by a crane (not shown). Here, "garbage" refers to waste that is collected from households and the like and should be incinerated. The collection routes and properties (e.g., moisture content) of the waste are various and also differ depending on the region and time. In this embodiment, the so-called "household garbage" is taken as a premise for explanation, but it is not limited to this.

[0020] (Pushing blower) The pushing blower 9 is for sending combustion air into the garbage incinerator. The combustion air from the pushing blower 9 is divided into primary air and secondary air. The ratio of this division can be adjusted by the opening degree of the secondary air damper 10. The opening degree of the secondary air damper 10 is controlled by the processing unit 8.

[0021] (Drying stoker, combustion stoker, afterburning stoker) The drying stoker 2, the combustion stoker 3, and the afterburning stoker 6 are each supplied with primary air preheated by the air preheater 19 through the corresponding pushing air dampers 21, 31, and 61. The drying stoker 2 dries the supplied garbage with the primary air. The combustion stoker 3 burns the garbage by supplying primary air to the garbage supplied from the drying stoker 2. The afterburning stoker 6 cools the ash generated by the combustion in the combustion stoker 3 and further burns the unburned components that could not be completely burned in the combustion stoker 3. The opening degrees of the pushing air dampers 21, 31, and 61 are controlled by the processing unit 8.

[0022] In addition, the dry stoker 2, the combustion stoker 3, and the afterburning stoker 6 are each provided with refuse layer level sensors 22, 32, and 62, respectively, so that the height (level) of the refuse on each stoker can be detected. Each output of the refuse layer level sensors 22, 32, and 62 is sent to the processing unit 8. As a result, when the height of the refuse on any of the stokers is too high (for example, exceeds a certain set value), the processing unit 8 changes the operation cycle so that the operation cycle of the relevant stoker becomes shorter, thereby promoting the combustion of the refuse.

[0023] (Primary combustion chamber and secondary combustion chamber) The exhaust gas from the primary combustion chamber 4 is sent to the secondary combustion chamber 5, where the unburned components in the exhaust gas are burned. The secondary combustion chamber 5 is supplied with secondary air branched from the primary air via the secondary air damper 10. The downstream side of the secondary combustion chamber 5 is a boiler 11 having a superheater or the like for recovering the heat of the exhaust gas.

[0024] The exhaust gas from the boiler 11 of the secondary combustion chamber 5 is discharged from the chimney 17 in a detoxified state via the bag filter 12, the denitration reaction tower 13, the induced draft fan 14, the chimney damper 16, etc.

[0025] (Denitration reaction tower) The denitration reaction tower 13 is for promoting the reaction between nitrogen oxides (NOx) in the exhaust gas and ammonia by a catalyst to render them harmless. Near the denitration reaction tower 13, a denitration reaction tower thermometer 131 for measuring the temperature of the denitration reaction tower 13 (more specifically, the temperature of the exhaust gas immediately after being discharged from the denitration reaction tower 13) is attached.

[0026] (Concentration measurement) An instrument 18 for measuring the concentration of substances in various exhaust gases is attached to the chimney 17. Specifically, as the instrument 18 of the present embodiment, a hydrogen chloride concentration meter 181, a sulfur oxide concentration meter 182, a nitrogen oxide concentration meter 183, a carbon monoxide concentration meter 184, an oxygen concentration meter 185, and a moisture concentration (water vapor concentration) meter 186 are used. Among these, the hydrogen chloride concentration meter 181, the nitrogen oxide concentration meter 183, and the sulfur oxide concentration meter 182 measure the concentration of harmful substances (hydrogen chloride, nitrogen oxides, sulfur oxides) in the exhaust gas and function as harmful substance concentration sensors.

[0027] (Exhaust gas recirculation damper) A part of the exhaust gas on the downstream side of the induced draft fan 14 is returned to the secondary combustion chamber 5 through the exhaust gas recirculation damper 15. The opening degree of the exhaust gas recirculation damper 15 is controlled by the processing unit 8, and thus the processing unit 8 of the present embodiment can control the recirculation gas rate. Here, the recirculation gas rate is the ratio of the exhaust gas returned to the secondary combustion chamber 5 among the exhaust gases discharged from the secondary combustion chamber 5 to the downstream side. It should be noted that it is also possible to use an exhaust gas circulation blower (not shown) instead of the exhaust gas recirculation damper 15.

[0028] (Processing unit) The processing unit 8 (see FIG. 2) is configured to receive measurement values from various instruments (such as a thermometer and a concentration meter) in the incinerator of the present embodiment.

[0029] The processing unit 8 of the present embodiment determines whether the temperature of the secondary combustion chamber 5 is higher or lower than the first set value. When the temperature of the secondary combustion chamber 5 is higher than the first set value, the recirculation gas rate is set to the first target value. When the temperature of the secondary combustion chamber 5 is lower than the first set value, the processing of setting the recirculation gas rate to the second target value is performed. Here, the first target value is set to be larger than the second target value.

[0030] As the processing unit 8 of the present embodiment, computer hardware, computer software, or a combination thereof can be used. The processing unit 8 may be a combination of a plurality of functional elements, or may be implemented by a plurality of functional elements distributed and arranged at remote locations. The detailed operation of the processing unit 8 will be described later as the operation of the garbage incinerator according to the present embodiment.

[0031] In addition, as the overall configuration of the garbage incinerator excluding the processing unit 8, it can be the same as the conventional one, so further detailed description of the entire garbage incinerator will be omitted.

[0032] (Operation of the garbage incinerator of the present embodiment) Next, the operation of the above-described garbage incinerator will be further described with reference to FIGS. 3 to 6.

[0033] (During steady operation) In the garbage incinerator of the present embodiment, the dust feeder 1, the drying stoker 2, the combustion stoker 3, and the afterburning stoker 6 operate at a predetermined cycle (for example, at 5-minute intervals), and periodically input garbage into the primary combustion chamber 4 and can stir and burn the garbage. This is the same as the conventional garbage incinerator. Note that this predetermined cycle is determined by the processing unit 8 in the present embodiment.

[0034] Here, in the garbage incinerator of the present embodiment, the processing unit 8 determines whether the temperature of the secondary combustion chamber 5 is higher or lower than the first set value (described later). Also, in the garbage incinerator of the present embodiment, the processing unit 8 also determines whether the temperature of the denitration reaction tower 13 is higher or lower than the second set value (described later).

[0035] (Operation based on the temperature of the secondary combustion chamber) The processing unit 8 receives the temperature of the secondary combustion chamber 5 from the secondary combustion chamber thermometer 51 and determines whether the temperature of the secondary combustion chamber 5 is higher or lower than the first set value as described above (step SA-1 in FIG. 3).

[0036] When the temperature of the secondary combustion chamber 5 is higher than the first set value, the processing unit 8 sets the recirculation gas ratio to the first target value (step SA-2 in FIG. 3). When the temperature of the secondary combustion chamber is lower than the first set value, the processing unit 8 sets the recirculation gas ratio to the second target value (step SA-3 in FIG. 3). Here, as described above, the first target value is set to a value larger than the second target value. However, as will be described later, in the present embodiment, the actual target value for the recirculation gas ratio is determined by comparing with the target value (described later) based on the temperature of the denitration reaction tower.

[0037] The first set value is, for example, any value between 900 and 950 °C, but is not limited to this.

[0038] The first target value is, for example, a recirculation gas ratio of 25%, and the second target value is, for example, a recirculation gas ratio of 20%, but is not limited to this. Different values can be used according to the plant situation and operation policy.

[0039] (Operation based on the denitration reaction tower temperature) The processing unit 8 receives the temperature of the denitration reaction tower 13 from the denitration reaction tower thermometer 131, and determines whether the temperature of the denitration reaction tower 13 is higher or lower than the second set value as described above (step SB-1 in FIG. 4).

[0040] When the temperature of the denitration reaction tower 13 is higher than the second set value, the recirculation gas ratio is set to the third target value (step SB-2 in FIG. 4). When the temperature of the denitration reaction tower 13 is lower than the second set value, the recirculation gas ratio is set to the fourth target value (step SB-3 in FIG. 4). Here, the fourth target value is set to a value larger than the third target value.

[0041] The second set value is, for example, any value between 185 and 190 °C, but is not limited to this.

[0042] As the third target value, for example, the recirculation gas rate is 20%, and as the fourth target value, for example, the recirculation gas rate is 30%, but it is not limited to this. Different values can be used according to the situation of the plant and the operation policy. Also, in this embodiment, the second target value and the third target value are the same, but they may be different values.

[0043] (Determination of the actual target value) By the above-described steps SA-1 to SA-3 and SB-1 to SB-3, at least two target values can be temporarily obtained. In this case, the processing unit 8 of this embodiment compares the two target values (corresponding to the "target values set in each process" in the present invention) with each other, and sets the larger target value as the actual target value. Further, the processing unit 8 uses this actual target value to adjust the opening degree of the damper 15 for exhaust gas recirculation, and adjusts the recirculation gas rate. Here, when increasing the opening degree of the damper 15 for exhaust gas circulation to an opening degree exceeding, for example, 70% does not increase the recirculation gas rate, the opening degree of the chimney damper 16 can be reduced (that is, the chimney damper 16 is closed) to increase the recirculation gas rate.

[0044] In this embodiment, since the combustion air from the forced draft fan 9 is distributed into primary air and secondary air, the total amount of combustion air is maintained substantially constant. Further, in this embodiment, since the configuration is such that the recirculation gas rate is adjusted, fluctuations in the amount of exhaust gas to be subjected to harmful substance removal can be suppressed to a low level. Then, there is an advantage that the management of the operation of the denitration reaction tower 13 and the chemical liquid injection in the removal of harmful substances becomes easy, and the operation of the plant becomes easy. On the contrary, if secondary air is introduced from the outside, the amount of combustion air itself fluctuates greatly. Moreover, when adjusting the recirculation gas amount instead of the recirculation gas rate, there is a possibility that the amount of exhaust gas to be subjected to harmful substance removal fluctuates greatly, and the management of the operation of the denitration reaction tower 13 and the chemical liquid injection in the removal of harmful substances becomes difficult, and the operation of the plant may become complicated.

[0045] Also, in this embodiment, since the target value can be changed according to the temperature of the denitration reaction tower 13, it becomes easier to maintain the function of the denitration reaction tower 13. Here, in this embodiment, as described above, the fourth target value (specifically 30%) is set to be larger than the third target value (specifically 20%). On the premise that when the temperature of the denitration reaction tower 13 drops, the activity of the denitration catalyst decreases, resulting in deterioration of the efficiency of the denitration reaction. When the recirculation gas rate increases, the amount of exhaust gas sent to the denitration reaction tower 13 slightly increases, so it becomes easier to maintain the temperature of the exhaust gas between the secondary combustion chamber 5 and the denitration reaction tower 13, and it becomes easier to maintain the temperature of the denitration reaction tower 13 at a high temperature. Thereby, the function of the denitration reaction tower 13 can be maintained. On the other hand, in this embodiment, since the recirculation gas rate is adjusted instead of the recirculation gas amount, as described above, fluctuations in the exhaust gas amount can be suppressed to a low level, and there is an advantage that the complexity of plant operation can be avoided.

[0046] Furthermore, in this embodiment, when the temperature of the secondary combustion chamber 5 is higher than the first set value, the recirculation gas rate can be increased (see step SA-2 in FIG. 3). Since the temperature of the recirculation gas is generally lower than the temperature of the secondary combustion chamber 5, according to this embodiment, overheating of the secondary combustion chamber 5 can be suppressed. Also, in this embodiment, when the temperature of the secondary combustion chamber 5 is lower than the first set value, the recirculation gas rate can be decreased (see step SA-3 in FIG. 3). Thereby, according to this embodiment, a decrease in the temperature of the secondary combustion chamber 5 can be suppressed.

[0047] On the other hand, in this embodiment, among the temporarily set target values, the higher target value is adopted as the actual target value (see step SC-2 in FIG. 5). Adopting a higher target value ultimately means prioritizing the temperature maintenance of the denitration reaction tower 13 over the temperature adjustment of the secondary combustion chamber 5. For example, even if the second target value (specifically, a recirculation gas rate of 20%) is obtained in step SA-3, if it is in the state of step SB-3, the fourth target value (specifically, a recirculation gas rate of 30%) will be adopted. Thereby, in this embodiment, the temperature of the denitration reaction tower 13 can be made high, and as a result, plant operation that prioritizes the suppression of harmful substance concentration becomes possible.

[0048] Also, in the present embodiment, the fourth target value is set to a value larger than the first target value. That is, even when the first target value is obtained as the recirculation gas rate required for temperature suppression in the secondary combustion chamber 5 (step SA-2 in FIG. 3), when the temperature of the denitration reaction tower 13 is too low (step SB-3 in FIG. 4), the fourth target value is used (step SC-2 in FIG. 5). As a result, the recirculation gas rate can be further increased with priority given to the operation of the denitration reaction tower 13. Also in this regard, plant operation that prioritizes suppression of harmful substance concentration becomes possible.

[0049] The transition state of the recirculation gas rate finally adopted by the above-described operation is shown in FIG. 6.

[0050] Note that the description of the above embodiment is merely an example and does not show the essential configuration of the present invention. The configuration of each part is not limited to the above as long as it can achieve the gist of the present invention.

[0051] In the description of the above embodiment, the actual target value is determined by comparing the first or second target value with the third or fourth target value. However, it is possible to use the first or second target value as the actual target value without performing this comparison. In this case, the temperature of the denitration reaction tower 13 is not considered.

[0052] Also, for example, during normal operation, operation based on the first target value or the second target value (see FIG. 3) is performed, and when the third target value or the fourth target value is set (see FIG. 4), the obtained target values are compared (see FIG. 5) to adjust the recirculation gas rate. Conversely, during normal operation, operation based on the third target value or the fourth target value is performed, and when the first target value or the second target value is set, the obtained target values are compared to adjust the recirculation gas rate.

[0053] Here, in this specification, "higher than or lower than the set value" shall include the case where it is the same as the set value. Therefore, when it is the same as the set value, whether to determine it as the high-temperature side or the low-temperature side can be appropriately determined according to the operation policy.

Explanation of Signs

[0054] 1 Dust Feeding Device 2 Dry Stoker 21 Dry Stoker Inlet Air Damper 22 Dry Stoker Waste Layer Level Sensor 3 Combustion Stoker 31 Combustion Stoker Inlet Air Damper 32 Combustion Stoker Waste Layer Level Sensor 4 Primary Combustion Chamber 41 Primary Combustion Chamber Thermometer 5 Secondary Combustion Chamber 51 Secondary Combustion Chamber Thermometer 52 Exhaust Gas Oxygen Concentration Meter 53 Exhaust Gas Carbon Monoxide Concentration Meter 6 Afterburning Stoker 61 Afterburning Stoker Inlet Air Damper 62 Afterburning Stoker Waste Layer Level Sensor 7 Garbage Hopper 8 Treatment Unit 9 Forced Blower 10 Secondary Air Damper 11 Boiler 12 Bag Filter 13 Denitration Reactor 131 Denitration Reactor Thermometer 14 Induced Draft Fan 15 Exhaust Gas Recirculation Damper 16 Chimney Damper 17 Chimney 18 Instruments 181 Hydrogen Chloride Concentration Meter 182 Sulfur Oxide Concentration Meter 183 Nitrogen Oxide Concentration Meter 184 Carbon Monoxide Concentration Meter 185 Oxygen Concentration Meter 186 Moisture Concentration (Water Vapor Concentration) Meter 19 Air preheater

Claims

1. A combustion control method for a garbage incinerator having a forced draft fan, a dust feeder, a drying stoker, a combustion stoker, a post-combustion stoker, a primary combustion chamber, and a secondary combustion chamber, the combustion air sent from the forced draft fan is distributed into primary air and secondary air, the primary air is further distributed and supplied to the drying stoker, the combustion stoker, and the post-combustion stoker, the secondary air is supplied to the secondary combustion chamber, a step of determining whether the temperature of the secondary combustion chamber is higher or lower than a first set value, when the temperature of the secondary combustion chamber is higher than the first set value, setting the recirculation gas ratio to a first target value, and when the temperature of the secondary combustion chamber is lower than the first set value, setting the recirculation gas ratio to a second target value, wherein the recirculation gas ratio is the ratio of the exhaust gas returned to the secondary combustion chamber among the exhaust gas discharged from the downstream side of the secondary combustion chamber, the first target value is set to a value larger than the second target value A combustion control method for a garbage incinerator.

2. Furthermore, the garbage incinerator has a denitration reaction tower for detoxifying nitrogen oxides in the exhaust gas discharged from the downstream side of the secondary combustion chamber, a step of determining whether the temperature of the denitration reaction tower is higher or lower than a second set value, when the temperature of the denitration reaction tower is higher than the second set value, setting the recirculation gas ratio to a third target value, and when the temperature of the denitration reaction tower is lower than the second set value, setting the recirculation gas ratio to a fourth target value, further comprising a step of comparing the target values set in each of the above steps among the first to fourth target values, and adjusting the recirculation gas ratio using the larger target value as the actual target value, the fourth target value is set to a value larger than the third target value The combustion control method for a garbage incinerator according to Claim 1.

3. The fourth target value is set to a value larger than the first target value The combustion control method for a garbage incinerator according to Claim 2.

4. A combustion control device for a garbage incinerator having a forced draft fan, a dust feeder, a drying stoker, a combustion stoker, a post-combustion stoker, a primary combustion chamber, a secondary combustion chamber, and a treatment unit, further comprising a secondary combustion chamber thermometer for measuring the temperature of the secondary combustion chamber, The combustion air fed from the forced blower is distributed into primary air and secondary air. The primary air is further distributed and supplied to the drying stoker, the combustion stoker, and the afterburning stoker. The secondary air is supplied to the secondary combustion chamber. The processing unit determines whether the temperature of the secondary combustion chamber measured by the secondary combustion chamber thermometer is higher or lower than a first set value, and when the temperature of the secondary combustion chamber is higher than the first set value, sets the recirculation gas rate to a first target value, and when the temperature of the secondary combustion chamber is lower than the first set value, sets the recirculation gas rate to a second target value. Here, the recirculation gas rate is the ratio of the exhaust gas returned to the secondary combustion chamber among the exhaust gas discharged from the secondary combustion chamber to the downstream side. The first target value is set to a value larger than the second target value. A combustion control device for a garbage incinerator.

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