JPH09126433A - Combustion control device for incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a combustion state in a furnace without a delay and to improve stability of a combustion state by a method wherein a feedback amount is computed based on an output of a generating energy amount measuring apparatus of a boiler and an output of a combustion temperature measuring apparatus, by comparing the computing result with an objective temperature, the result is outputted to an operation amount computer. SOLUTION: A produced steam amount measuring apparatus 10 is mounted as a generating energy amount measuring apparatus on a waste heat recovery boiler 11, and an output f5 from a steam produced amount measuring apparatus 10 is inputted to a combustion control system 15. Further, an output f1 of a temperature sensor (temperature measuring apparatus) 1 and an output f5 of a steam generating measuring apparatus 10 are converted into a signal one by one and inputted to a combustion control system 15. A relation therebetween is estimated in a form containing a delay of the temperature measuring apparatus and computed by a feedback computer 5. A differential content between a feedback amount f6 calculated by the feedback computer 5 and a target temperature f4 set by a setter 6 is obtained by a comparator 2, and an operation amount computer 3 computes a proper operation amount f3 according to the differential content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for an incinerator that incinerates or thermally decomposes municipal solid waste, industrial waste, etc., and more particularly to a device having excellent responsiveness.

[0002]

2. Description of the Related Art Various incinerators have been developed in order to efficiently incinerate or pyrolyze municipal waste, industrial waste, etc., which are increasing in number in recent years. Above all, there has been a demand for an excellent combustion control device that controls the combustion temperature in the incinerator so as to deal with various types of waste.

FIG. 7 is a device configuration diagram of an incinerator to which such a combustion control device is applied. In FIG. 7, the furnace body 9
A dust supply rotor 12 is provided to feed a predetermined amount of dust 13 to the exhaust gas 21, and the exhaust gas 21 generated in the furnace body 9 is extracted through the flue 22. Since the exhaust gas 21 has a high temperature, the waste heat boiler 11 is connected to a predetermined portion of the flue 22 in order to recover the thermal energy of the exhaust gas 21.
In order to incinerate or thermally decompose industrial waste efficiently, it is necessary to keep the combustion temperature in the furnace body 9 at a predetermined level. Therefore, the temperature measuring device 1 as a temperature sensor is attached to a predetermined position of the furnace body 9, and the combustion control system 14 that outputs the output f1 of the temperature measuring device 1 is provided. The combustion control system 14 forms a feedback control circuit that receives a rotor rotation speed f2 of the supply rotor 12 and outputs a command signal to the supply rotor 12.

The operation of the above-mentioned combustion furnace is as follows. First, the garbage supply rotor 1 which is a constant supply type feeder
2 to 13 are thrown into the furnace body 9. The thrown refuse 13 is incinerated or pyrolyzed in the furnace body 9. When the amount of dust 13 charged changes, the combustion temperature in the furnace body 9 also changes. Therefore, in the combustion control system 14, after the predetermined combustion temperature is set, the waste 1 from the waste supply rotor 12 is adjusted so that the combustion temperature in the furnace body 9 becomes the target temperature.
It is decided by the input amount of 3. Therefore, when the combustion temperature detected by the temperature measuring device 1 is lower than the target temperature, the rotation speed of the dust supply rotor 12 is increased, and when the combustion temperature detected by the temperature measuring device 1 is higher than the target temperature, the dust supply rotor 12 is rotated. Combustion control system 1 for controlling the rotation speed
4 is going.

In order to describe the temperature control in the temperature control system 14 in detail, the combustion control block diagram of FIG. 8 will be described. It comprises a setter 6 for setting and outputting a desired target temperature f4, a comparator 2, and a manipulated variable calculator 3. The operation amount f3 from the operation amount calculator 3 is output to the operation means 12 such as a dust supply rotor, and the combustion temperature of the furnace body 9 affected by the operation means 12 is detected by the temperature measuring device 1 as a temperature sensor. .

During operation, the target temperature f4 is input to the setting device 6. Then, the target temperature f4 is input to the comparator 2,
The difference from the output f1 of the temperature sensor (temperature measuring device) 1 is output from the comparator 2 to the manipulated variable calculator 3. The manipulated variable calculator 3 calculates an appropriate manipulated variable f3 according to the type of the operating means 12 based on the output from the comparator 2 and outputs it to the operating means 12. The manipulated variable f3 is, for example, the amount of the dust 13 input, and the combustion temperature in the furnace body 9 is changed by changing the amount. If the combustion temperature in the furnace body 9 is an appropriate temperature, the combustion temperature is set as it is. Temperature sensor (temperature measuring device)
1 detected combustion temperature f3 and target temperature f from setter 6
If 4 is the same, the manipulated variable f3 from the manipulated variable calculator 3 is kept constant. Since the combustion temperature in the furnace body 9 fluctuates at any time according to the amount of generated heat of the dust that is input, if it deviates from the target temperature, depending on the difference between the output f1 of the temperature sensor (temperature measuring device) 1 and the target temperature f4. Then, the manipulated variable calculator 3 increases / decreases the manipulated variable f3 and repeats temperature control so that an appropriate combustion temperature is maintained.

[0007]

However, the incinerator 9
Since the temperature inside is high, a temperature sensor (temperature measuring device)
1 cannot be mounted in such a way that it is directly exposed to the furnace. That is, the temperature sensor (temperature measuring device) is attached to the wall surface of the furnace body 9 in a state of being covered with a metal tube, a ceramic tube or the like in order to protect it from a failure caused by a high temperature. Due to such protection means, the measured value of the temperature sensor (temperature measuring device) 1 is considerably delayed from the actual temperature in the furnace body 9. Since the temperature control is performed by the measured value with the delay, the reaction of the control system is naturally delayed and there is a problem that the control performance is limited.

This phenomenon will be described with reference to FIG. FIG.
9A is a change diagram of input calories, FIG. 9B is a change diagram of temperature in the furnace body, and FIG. 9C is a change diagram of operation amount of the temperature control system. As shown in FIG. 9A, for example, when dust with a low carbon content is temporarily supplied, a concave change A1 occurs in the input calories. Then, as shown in FIG. 9B, the change A2 of the measured value f1 of the temperature in the furnace becomes a response with some delay. Therefore, as shown in FIG. 9C, the change A3 in the manipulated variable f3 is the measured value f1 of the furnace temperature.
Since it is a control that uses, there will be a delay.

The present invention has been completed as a result of extensive studies to solve the above-mentioned problems of the prior art, and the present invention provides both the amount of steam generated from a waste heat boiler and a temperature measurement value. It is an object of the present invention to provide a combustion control device for an incinerator, in which the combustion state in the furnace is estimated without delay by using the value of, and a combustion state with high stability can be obtained.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is a furnace main body for incinerating or thermally decomposing municipal solid waste to generate exhaust gas, and A boiler that recovers the thermal energy of exhaust gas, a temperature measuring device that is attached to the furnace body to detect the combustion temperature in the furnace body, and an operation amount such as a dust supply speed to control the combustion state in the furnace body. A manipulated variable calculator for calculating and outputting, a generated energy amount measuring device for detecting the generated energy amount in the boiler, and a feedback amount based on the output of the generated energy amount detecting means and the output of the temperature measuring device. A combustion control device for an incinerator, comprising: a feedback amount calculator; and a comparator that compares the output of the feedback amount calculator with a set target temperature and outputs the comparison result to the manipulated variable calculator. That. Temperature sensor (temperature detection means)
In order to avoid the delay of, the amount of steam generated from the boiler installed in the incinerator is used as the measurement value. The amount of steam is closely related to the combustion temperature in the furnace, and can be measured without the delay of a temperature sensor (temperature detecting means). However, note that the amount of steam is affected not only by the combustion temperature in the furnace but also by the flow velocity of the exhaust gas and the fluid around the heat exchanger, so the relationship between the combustion temperature in the furnace and the amount of steam is clearly understood. Without it, it cannot be used for control. In addition, if factors other than the amount of dust adhering to the wall of the boiler tube and the temperature are stabilized only by the amount of steam due to changes over time, the combustion temperature in the furnace will deviate from the appropriate value and will be either high or low. Excessive pollution and exhaust gas pollution (CO, NO _x
Etc.) occurs. Therefore, while taking the above precautions into consideration, the relationship between the temperature measurement value and the steam generation amount is estimated at any time, and after grasping this relationship, this is used for combustion control. By doing so, the relationship between the measured temperature value and the amount of steam can be estimated at any time, and the relationship can be grasped, whereby a combustion state with excellent responsiveness and high stability can be obtained. According to a second aspect of the present invention, the temperature measuring device is attached to the furnace body via a protection means. Although the protection means protects the temperature measuring device from high temperatures, the measured temperature is delayed, so the above estimation is effective. According to a third aspect of the present invention, the feedback amount calculator corrects and estimates the output of the temperature measuring device from the output of the generated energy amount detecting means. As described above, the amount of generated energy also changes due to various factors. Therefore, the relationship between the temperature measurement value and the amount of steam can be estimated at any time, and stable output is realized by correcting the output of the temperature measuring device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an incinerator provided with the combustion control device of the present invention, and FIG. 2 is a combustion control block diagram of the present invention. 1 and 2, parts that operate in the same way as in FIGS. 7 and 8 are given the same reference numerals and explanations thereof are omitted.

First, an incinerator equipped with the combustion control device of the present invention will be described with reference to FIG. 7 differs from the device configuration shown in FIG. 7 in that a boiler 11 for recovering waste heat is equipped with a generated steam amount measuring device 10 as a generated energy amount measuring device, and an output f5 from the steam generation amount measuring device 10 is input to the combustion control system 15. It is the point that it is configured to do. Next, in the control block of FIG. 2, the difference from FIG. 8 is that a feedback amount calculator 5 is provided between the temperature sensor 1 and the comparator 2, and the steam generation amount measuring device 4 is connected to this feedback amount calculator 5. It is a point.

The operation of the incinerator equipped with the combustion control device of the present invention will be described below. In FIG. 1, first, the setting device 6
Thus, the desired temperature in the incinerator, that is, the target temperature f3 is set in the combustion control system 15. Next, refuse supply rotor 12
The trash 13 enters and is supplied to the furnace body 9. Garbage 13
Waste heat of the exhaust gas 21 generated at the time of incineration is recovered by the boiler 11 through the flue 22 above the furnace body 9. (Up to this point, it is similar to an incinerator equipped with a conventional combustion control device). The combustion control in the furnace body 9 is performed by measuring the combustion temperature in the furnace body 9 with a temperature sensor output 7 attached to the furnace body 9, and measuring the steam generation amount 1 provided in the boiler 11.
This is performed by sending both the measured steam generation amount in the boiler 11 at the output f5 of 0 to the combustion control system 15. The operation amount calculated by the combustion control system 15 is sent to the dust supply rotor 12 as a command signal f3, and is operated at an appropriate rotor rotation speed 15. The dust supply rotor 12 sends the rotor rotation speed f2 to the combustion system 15 at any time, and feedback control is performed so as to match the command signal f3.

The dust feed rotor 12 as one of the operating means is, for example, a constant feed type feeder, and has a structure capable of throwing dust of a volume corresponding to the rotation speed of the rotor into the incinerator body 9. . In the furnace body 9 of the incinerator, the upper part of the furnace body 9 is tapered so that the heat generated in the incineration is used in the boiler 11, so that the heat can be easily collected. A flue 22 is connected to the upper part of the furnace body 9 so that the exhaust gas does not leak outside,
The boiler 11 is connected to the tip of the flue 22. Since a pipe containing water is installed in advance in the boiler 11, the water exchanges heat with the exhaust gas to become steam. The steam generation amount measuring device 10 measures the steam generation amount of the boiler 11. This steam generation amount measuring device 10 is provided in the path of the steam extracted from the boiler 11, and measures the flow rate of the steam generated in the boiler 11, for example, by measuring the pressure change of a differential pressure gauge, and measures the flow rate based on it. It is total. Output f from this differential pressure flow meter
5 is output to the combustion control system 15.

Inside the furnace body 9, a temperature measuring instrument 1 used for controlling the combustion temperature is embedded in the upper side wall of the furnace body 9. As the temperature measuring device 1, for example, a thermocouple that uses a thermoelectromotive force corresponding to the difference in temperature between the reference point and the temperature measurement point is used. Thermocouples have the advantages of simple structure and wide range temperature measurement. However, due to the structure in which the thermocouple is incorporated in a protection tube made of metal, ceramic, or the like that can withstand high temperatures, there is a delay in measuring the combustion temperature in the furnace body. Output f of temperature sensor (temperature measuring device) 1
1 and the output f5 of the steam generation amount measuring device 10 are sequentially converted into signals and input to the combustion control system 15. The combustion control system 15 estimates the relationship between the temperature measurement value and the amount of steam at any time. The combustion control system 15 estimates the relationship in a form including the delay of the temperature measuring device, and the feedback amount calculator 5 of FIG. 2 performs the calculation for that purpose.

The method of estimating the relationship between the temperature measurement value and the amount of steam in the feedback amount calculator 5 of FIG. 2 will be described below. The relationship between the measured temperature value Tm and the actual furnace temperature T can be expressed by the following equation. Tm (t) = F (T (t-d)) (1) Here, F is a low pass filter, t is time, and d is dead time of the temperature measuring device. In addition, the furnace temperature and the generated steam amount S
The relationship between and can be expressed by the following equation. S = a · T (t) + b (2) Here, a and b are coefficients determined by the state of the boiler and surrounding conditions. These coefficients are constantly changing and it is difficult to grasp them all. However, by obtaining the average value of these coefficients in a certain time zone, it is possible to estimate the steam generation amount when the combustion state in the furnace is kept stable at the target temperature. As a result, it can be estimated that if the steam generation amount is large, the combustion is overloaded, and if the steam generation amount is small, the combustion is inactive, and control can be performed based on this. The coefficient estimation is as follows. The following equation is obtained from the equations (1) and (2). Tm (t) = F (p · S (t−d) + q) (3) However, p and q can be expressed as follows by the parameters a and b. p = 1 / a q = −b / a If the dead time d is measured in advance, the equation (3) can be identified by the method of least squares, and the temperature measurement value is delayed by the dead time. By using the average value of, the low-pass filter can be ignored and the calculation can be simplified.

A block diagram of the combustion control system 15 of the present invention using the above estimation method is shown in FIG. This combustion control system includes a setter 6, a comparator 2, a manipulated variable calculator 3, a feedback amount calculator 5, and a manipulated variable calculator 3. The feedback amount calculator 5 is a calculator that performs calculation by the above estimation method. Manipulated variable calculator 3
Is the difference between the feedback amount f6 calculated by the feedback amount calculator 5 and the target temperature f4 set by the setter 6, and the appropriate manipulated variable f3 is calculated according to this difference.
Is a computing unit for computing. The feedback amount f6 is the measured value itself measured by the temperature measuring device 1 in the case of the prior art of FIG. 8, but is the value in which the delay of the temperature measuring device is corrected by the steam generation amount in the case of the present invention. Are different. During operation, the manipulated variable f3 calculated by inputting the difference between the target temperature f4 and the feedback amount f6 into the manipulated variable calculator 3 becomes the rotation speed of the dust supply rotor 12 as the operating means. If the combustion temperature in the furnace body deviates from the target temperature f4 due to a change in the heat value of the dust, the above operation is repeated to stabilize the combustion temperature.

FIG. 3 shows that in the combustion control using the value in which the delay of the temperature measuring device is corrected by the amount of steam generated in the waste heat boiler as described above, the change in the manipulated value shows a quick reaction. FIG. 3 is a change diagram of the combustion system, and FIG.
Is a change in input calorie, FIG. 3 (b) is a change in steam generation amount measurement value, and FIG. 3 (c) is a graph showing change in operating amount of the combustion system of the present invention. In FIG. 3A, when the input calorie changes at the concave change point B1, FIG.
As described above, it can be seen that the change in the measured value f5 of the amount of steam generated by the waste heat boiler shows a considerably quick response like the change point B2. In FIG. 3 (c), the change in the manipulated variable f3 of the combustion system can be naturally changed quickly like the change point B3 because of the control using the measured value f5 of the steam generation amount. Compared with the change in the manipulated variable in the change diagram of the conventional combustion system shown in FIG. 9C, the difference in response time is noticeable.

Further, as a practical combustion control device, in order to efficiently incinerate dust and obtain a stable combustion state, FIG.
In addition to the above configuration, a refuse supply conveyor 12 is connected to the refuse supply rotor 12, and the operation amount of the combustion control system 15 is not limited to the rotor rotation speed but also the primary air flow rate 19 and the primary air temperature 2
It may be extended to zero. FIG. 4 is a device block diagram of another temperature control device of an incinerator in which the target of the manipulated variable to be controlled is expanded. The parts that operate in the same manner as in FIG. In order to convey the refuse to the refuse supply rotor 12, a refuse supply conveyor 18 using a belt conveyor or the like is connected to the refuse supply rotor 12. Further, the waste supply conveyor 18 has a control method based on an identification model capable of ignoring the influence of disturbance (fluctuation of the way dust is placed, etc.) in the combustion control system 15 to control the speed of the belt conveyor. . A pipe is connected to the bottom of the furnace body 9 to supply primary air. This pipe is equipped with a temperature variable device 20 and a variable valve 19 for freely changing the air temperature and the air flow rate. When operating,
In addition to the operation of FIG. 1, waste is supplied from the waste supply conveyor 18, and air is blown out from the bottom of the incinerator to float the waste. It can be incinerated efficiently by suspending the garbage. At this time, the air flow rate and the air temperature are controlled by the manipulated variables from the combustion control system 15 so that the combustion temperature becomes stable. The values of the air flow rate and the air temperature are as required.
Has been sent to 5.

FIG. 5 is used to explain the combustion control system 15 in detail. The arrows pointing toward the block diagram show the flow of data, and the arrows passing through the block show that the parameters in the block change depending on the data. In this block diagram, the primary air flow rate and the primary air temperature are newly added to the manipulated variables in FIG.
In addition, the speed of the waste supply belt is controlled by the identification model. The identification model 16 is for controlling the speed of the belt conveyor by ignoring the influence of disturbance (fluctuation in how dust is placed, etc.), and its control method will be described below. A primary model is used that inputs the conveyor speed and outputs the measured temperature value. y [k + 1] + ay [k] = bu [k] (1) where y [k] is an output, u [k] is an input, and a and b are unknown parameters. Therefore, a and b are obtained.
In order to obtain a and b, an adaptive identification method with a dead zone such as equation (3) is used. The dead zone is m [k]. θ _e [k] = θ _e [k−1] + K [k] m [k] (2) m [k] = 0: W ₁ ≦ e [k] ≦ W _u = e [k] −W ₁ : e [k] <W ₁ (3) = e [k] -W _u: e [k]> W _u e [k] = y [k] -y _e [k] (4) y _e [k + 1] = theta _e ^T [k] phi [k] (5) K [k] = P [k] phi [k] (6) P [k] = (I-K [k] phi ^T [k]) P [k −1] / λ (7) θ _e ^T [k] = [− a _e [k] be _e [k]] (8) φ ^T [k] = [y [k] u [k]] (9) a _e [k], b _e [k] a, an estimate of b, e [k] estimates the _{error, W 1 <0, W u} > 0 is the lower limit of each of the dead zone, the upper limit, 0 <lambda <1 is a forgetting factor. here,
The dead zone calculation method of equation (3) is converted to equation (10). m [k] = 0: W ₁ ≦ e [k] ≦ W _u = e [k]: e [k] <W ₁ , e [k]> W _u (10) It becomes an identification model that ignores the influence. Using this identification model, the conveyor speed is controlled from the values of the rotor speed and the temperature measuring device to stabilize the combustion state of the incinerator.

During the operation, since the identification model 16 is added, the influence of the disturbance during operation can be ignored in addition to the operation shown in FIG. Here, the relationship between the steam generation amount and the temperature measurement value was estimated, and the combustion state in the furnace was estimated and controlled without delay by using both values. By adding a correction based on the amount of combustion air blown into the furnace, it becomes possible to perform more accurate relationship estimation and control.

[0022]

EXAMPLE An incinerator having the combustion apparatus of the present invention shown in FIG. 1 and an incinerator having the conventional combustion apparatus shown in FIG. FIG. 6 shows the result. Hereinafter, description will be made with reference to FIG. FIG. 6A shows an incinerator equipped with the combustion apparatus of the present invention, in which the target temperature is set to 860 ° C. and the temperature in the furnace is measured for 1 hour. FIG. 6 (b) shows an incinerator equipped with a conventional combustion device,
The target temperature was set to 850 ° C. and the furnace temperature was measured for 1 hour. According to the measurement results, the average temperature fluctuation in 1 hour was almost the target temperature in both cases, but the magnitude of the fluctuation in the temperature in the furnace was much smaller in the incinerator of the present invention as indicated by the standard deviation. It can be seen that a combustion state that is suppressed and has high stability is obtained.

[0023]

As described above, according to the first aspect of the present invention, the combustion in the furnace is performed based on the steam generation amount and the temperature measurement value, despite the temperature measurement with a delay. The temperature can be kept constant, which makes it possible to stabilize combustion and reduce pollution. The invention described in claim 2 is claim 1
The described effect works effectively when using a temperature measuring device which is prone to delay as a protection means. The invention according to claim 3 is particularly effective when the effect according to claim 1 is used when a feedback amount calculator for correcting and estimating the output of the temperature measuring device from the output of the generated energy amount detecting means is used. To do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an incinerator equipped with a combustion control device of the present invention.

FIG. 2 is a combustion control block diagram of the present invention.

FIG. 3 is a change diagram of combustion control according to the present invention.

FIG. 4 is a schematic view of another incinerator equipped with the combustion control device of the present invention.

FIG. 5 is a combustion control block diagram in FIG.

FIG. 6 is a comparison diagram of an embodiment of the incinerator of the present invention and the conventional incinerator.

FIG. 7 is a schematic diagram of an incinerator having a conventional combustion control device.

FIG. 8 is a conventional combustion control block diagram.

FIG. 9 is a change diagram of conventional combustion control.

[Explanation of symbols]

 1 Temperature Measuring Device 2 Comparator 3 Manipulation Amount Calculator 5 Feedback Amount Calculator 9 Furnace Main Body 10 Generated Steam Amount Measuring Device (Generated Energy Amount Measuring Device) 11 Boiler 12 Waste Supply Rotor (Operating Means) 15 Combustion Control System f1 Measured Temperature f3 manipulated variable f4 target temperature f5 generated steam amount

Claims (3)

[Claims] 1. A furnace body for incinerating or thermally decomposing municipal waste or the like to generate exhaust gas, a boiler for recovering thermal energy of the exhaust gas, and a temperature attached to the furnace body for detecting combustion temperature in the furnace body. A measuring instrument, a manipulated variable computing device for computing and outputting a manipulated variable such as a dust supply speed in order to control the combustion state in the furnace body, and a generated energy amount measuring instrument for detecting the amount of energy generated in the boiler. , A feedback amount calculator for calculating a feedback amount based on the output of the generated energy amount measuring device and the output of the temperature measuring device, and comparing the output of the feedback amount calculating device with a set target temperature, the manipulated variable A combustion control device for an incinerator, which comprises a comparator for outputting to a computing unit. 2. The combustion control device for a combustion furnace according to claim 1, wherein the temperature measuring device is attached to the furnace body via a protection means. 3. The combustion control device for a combustion furnace according to claim 1, wherein the feedback amount calculator corrects and estimates the output of the temperature measuring device from the output of the generated energy amount measuring device.