JPH1114027A - Method of controlling combustion of incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the suppression of generating hazardous gas as dioxin, etc., by detecting the density of carbon monoxide instantaneously inside an incinerating furnace and changing the quantity of secondary combustion air corresponding to the detected density of the carbon monoxide. SOLUTION: Combustible is gasified inside a fluidized bed 2 and combusted at a free board 3. A CO density detector 14 using a semiconductor laser is arranged to the middle step of the free board 3. The CO density detector 14 is a carbon monoxide density detecting means enabling the measuring of the CO density inside the fluidized bed instantaneously. The output X1 of the CO density detector 14 is input to a computing unit 15. The processing unit 15 calculates the quantity of the secondary combustion air Y1 for suppressing CO with PID operation, etc. When the CO density is higher, the secondary combustion air is increased decreasing the CO density. The quantity of the secondary combustion air Y1 calculated by the processing unit 15 is output to a secondary combustion air control valve 7 and the opening of the valve is adjusted for obtaining the set up quantity of the secondary combustion air Y1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling combustion in an incinerator.

[0002]

2. Description of the Related Art When a burnable material such as municipal waste that cannot be supplied in a fixed amount is introduced into an incinerator, the variation in the amount of the burned material is directly affected by fluctuations in the combustion gas and oxygen (O) in the combustion gas.
₂ ) Concentration variation, dioxin, NOx
And other hazardous gases. Especially,
When the O ₂ concentration was reduced, a large amount of carbon monoxide (CO) was generated, which was a cause of generating dioxin having a high correlation with the CO concentration. There is a method of injecting a sufficient amount of secondary combustion air so as not to generate CO. However, when the O ₂ concentration is increased, the correlation with the O ₂ concentration is high.
Ox is generated.

Conventionally, the following countermeasures have been taken as a control method for suppressing such harmful gases such as dioxin and NOx. 1) The CO concentration was detected by an exhaust gas analyzer and the amount of secondary combustion air was changed. That is, when the CO concentration increases, the secondary combustion air amount is increased to lower the CO concentration,
When the O concentration became sufficiently low, the secondary combustion air amount was returned.

[0004] 2) to detect the O ₂ concentration by the exhaust gas analyzer,
The amount of combustion air was changed. That is, when the O ₂ concentration is high, the amount of combustion air is reduced, and when the O ₂ concentration is low, the amount of combustion air is increased to keep the O ₂ concentration constant.

3) The furnace outlet temperature and the exhaust gas O ₂ concentration are detected,
The primary combustion air amount was changed. That is, when the combustion amount is large, the primary combustion air amount is reduced to suppress the gasification rate, and when the combustion amount is small, the primary combustion air amount is increased to activate the gasification rate. As a result, the amount of heat generated by the combustion is kept constant, and the fluctuation of the combustion is suppressed.

[0006] Conventionally, when high-calorie combustion products, such as plastics, which cannot be supplied in a fixed amount and are injected into an incinerator, the combustion products are quickly gasified in a short time. , Causing fluctuations in the amount of steam generated.

Conventionally, as a control method for suppressing such fluctuations in the amount of generated steam, the amount of generated steam is detected and the amount of fluidized air is changed. That is, when the amount of generated steam is large, the amount of fluidized air is reduced to suppress the gasification rate, and when the amount of generated steam is small, the amount of fluidized air is increased to activate the gas or velocity. As a result, the amount of generated steam was kept constant.

[0008]

However, the conventional combustion control apparatus has the following problems. 1) In the control device that detects the CO concentration (or O ₂ concentration) and changes the amount of secondary combustion air, the CO concentration (or O ₂ concentration)
₂ ) whether the function to keep the concentration constant works effectively
It depends on the detection accuracy of the CO concentration (or the O ₂ concentration).
As a means for detecting the CO concentration (or O ₂ concentration), there is a method using an exhaust gas analyzer.
Since the exhaust gas is detected at the furnace outlet, it takes time to reach the measurement point, and there is a time delay. Therefore, it could not be a valid control signal. That is, in the conventional exhaust gas analyzer, the gas is guided from the point to be measured to the analyzer through a pipe and analyzed, and the length of the actual apparatus is reduced by 20 to 30 m. Therefore, it took about 30 seconds to 1 minute from obtaining the gas to obtaining the analysis result.

2) Dioxin has a high correlation with the CO concentration in the furnace, and as the CO concentration in the furnace increases, the dioxin tends to increase. Further, NOx is high correlation between the O ₂ concentration in the furnace, NOx also tends to increase when the O ₂ concentration in the furnace increases. Therefore, in the combustion control method, whether or not harmful gases such as dioxin and NOx can be suppressed depends on how to suppress both the O ₂ concentration in the furnace and the CO concentration in the furnace, and the furnace outlet temperature and the exhaust gas O 2 _{(2) The} conventional control method for detecting the concentration and suppressing the combustion fluctuation has a problem that the harmful gas suppression control with high accuracy cannot be performed.

3) In a fluidized-bed furnace for industrial waste, etc., usually,
The operation is performed in a state where the excess air ratio in the fluidized bed portion is 1.0 or less. However, since fuels with different amounts of heat generated per unit volume are charged, the excess air ratio in the fluidized bed greatly varies and is 1.1 or more. It may be. FIG. 5 shows the relationship between the excess air ratio in the fluidized bed and the combustion efficiency.

When the excess air ratio in the fluidized bed is less than 1.0, increasing the amount of fluidized air improves combustion efficiency and raises the temperature. Further, when the amount of fluidized air is reduced, the combustion efficiency is deteriorated and the temperature is lowered. Therefore, when the amount of generated steam is small, it is necessary to increase the flow rate of the fluidizing air.

When the excess air ratio in the fluidized bed is greater than 1.1, increasing the amount of fluidized air decreases the combustion efficiency due to the cooling effect and lowers the temperature. Efficiency improves, temperature rises. Therefore, when the amount of generated steam is small, it is necessary to reduce the flow rate of the fluidizing air.

When the excess air ratio in the fluidized bed is 1.0 to 1.1, it is necessary to keep the O ₂ concentration at an appropriate level and not to fluctuate the operating device. Therefore, in the conventional control method in which the control parameter is fixed and the deviation of the steam generation amount is detected to change the fluidized air amount, the operating device is operated in a bad direction (in a direction in which the deviation of the steam generation amount increases). There was a possibility to control. In addition, depending on the property of the waste, the appropriate control range of the air excess ratio in the fluidized bed is 1.0 to 1.0.
Instead of 1.1, it may be changed to about 0.75 to 0.9.

The present invention has been made in view of such circumstances. First, a carbon monoxide concentration detecting means and a secondary combustion air control means capable of instantaneously measuring the carbon monoxide concentration in an incinerator are provided. Detects the concentration of carbon monoxide without time delay and changes the amount of secondary combustion air according to the detected concentration of carbon monoxide to accurately detect the concentration of CO without time delay, thereby reducing harmful gases such as dioxin. It is an object of the present invention to provide a combustion control method in an incinerator that can suppress the generation of combustion.

Second, the present invention comprises oxygen concentration detecting means capable of instantaneously measuring the oxygen concentration in the incinerator and primary combustion air control means, and detects and detects the oxygen concentration without time delay. It is an object of the present invention to provide a combustion control method in an incinerator in which the primary combustion air amount is changed in accordance with the oxygen concentration to accurately detect the O ₂ concentration without time delay, thereby suppressing the generation of harmful gases such as dioxin. Aim.

Third, the present invention provides a temperature detecting means for detecting a temperature of a combustion portion in an incinerator, an oxygen concentration in the incinerator,
Equipped with oxygen concentration detecting means capable of instantaneously measuring carbon monoxide concentration, carbon monoxide concentration detecting means, and primary and secondary combustion air control means, and detecting the combustion state without time delay,
By using the detected combustion state signal to change the primary combustion air amount and the secondary combustion air amount so as to maintain the furnace temperature, the furnace oxygen concentration, and the carbon monoxide concentration in the furnace at appropriate values, the furnace temperature, An object of the present invention is to provide a combustion control method in an incinerator that can accurately detect the in-furnace O ₂ concentration and the in-furnace CO concentration without time delay and thereby suppress generation of harmful gases such as dioxin.

Fourth, the present invention relates to a method for controlling the oxygen concentration in an incinerator,
Oxygen concentration detecting means capable of instantaneously measuring carbon monoxide concentration, carbon monoxide concentration detecting means, detecting means for detecting the amount of steam generated in a boiler connected to an incinerator, and air control means for primary and secondary combustion The excess air ratio (actual air amount / theoretical air amount) in the primary combustion field is estimated based on the oxygen concentration signal and the carbon monoxide concentration signal, and a control parameter is determined based on the excess air ratio. By controlling the amount of combustion air using parameters, the combustion state in the furnace can be accurately detected without time delay based on the output of the O ₂ concentration detector in the furnace and the output of the CO concentration detector, thereby generating steam. It is an object of the present invention to provide a combustion control method in an incinerator that can keep the amount constant.

[0018]

According to a first aspect of the present invention, the charged combustion material is gasified in a primary combustion field by primary combustion air sent from a lower portion of an incinerator, and gasified combustible gas is sent from a middle stage of the incinerator. The amount of heat generated by the combustion is kept constant irrespective of the fluctuation of the combustibles introduced into the furnace, and the dioxin, N
A combustion control method in an incinerator for suppressing generation of toxic gas such as Ox, comprising a carbon monoxide concentration detecting means capable of instantaneously measuring a carbon monoxide concentration in the incinerator and a secondary combustion air control means. A method for controlling combustion in an incinerator characterized by detecting the concentration of carbon monoxide without time delay, and changing the amount of secondary combustion air according to the detected concentration of carbon monoxide.

[0019] The second invention of the present application is that gasified combustible gas is converted into gas by a secondary combustion air sent from a middle stage of an incinerator by primary combustion air sent from a lower part of the incinerator, and gasified combustible gas is sent from the lower part of the incinerator. A method for controlling combustion in an incinerator that suppresses the generation of toxic gases such as dioxins and NOx while keeping the amount of heat generated by combustion constant irrespective of fluctuations in the combustibles injected into the furnace. Equipped with oxygen concentration detecting means capable of instantaneously measuring oxygen concentration in the air and primary combustion air control means, detecting the oxygen concentration without time delay, and changing the primary combustion air amount according to the detected oxygen concentration. A combustion control method in an incinerator characterized by the following.

According to a third invention of the present application, the charged combustion material is gasified in a primary combustion field by primary combustion air sent from a lower portion of the incinerator, and the gasified combustible gas is converted into gas by secondary combustion air sent from a middle stage of the incinerator. A method for controlling combustion in an incinerator that suppresses the generation of toxic gases such as dioxins and NOx while keeping the amount of heat generated by combustion constant irrespective of fluctuations in the combustibles injected into the furnace. Temperature detection means for detecting the temperature of the combustion part in the furnace, oxygen concentration detection means for instantly measuring the oxygen concentration and carbon monoxide concentration in the incinerator, carbon monoxide concentration detection means, and primary and secondary combustion Air temperature control means for detecting the combustion state without time delay and using the detected combustion state signal to maintain the furnace temperature, the furnace oxygen concentration, and the furnace carbon monoxide concentration at appropriate values. A combustion control method in a incinerator, wherein varying the amount of combustion air and secondary combustion air amount.

According to a fourth aspect of the present invention, a high-temperature fluidized medium is gasified in a primary combustion field in which a high-temperature fluidized medium is fluidized by fluidizing air fed from a lower portion of the incinerator, and the combustible gas is converted to a gaseous combustible in a middle stage of the incinerator. Combustion by the secondary combustion air sent from the incinerator, and controlling the amount of fluidized air and the amount of fuel supply based on the deviation of the amount of generated steam, the oxygen concentration and carbon monoxide concentration in the incinerator Each comprising an instantaneously measurable oxygen concentration detecting means, a carbon monoxide concentration detecting means, a detecting means for detecting a steam generation amount of a boiler connected to an incinerator, and a primary / secondary combustion air control means,
The excess air ratio (actual air amount / theoretical air amount) in the primary combustion field is estimated from the oxygen concentration signal and the carbon monoxide concentration signal,
A combustion control method in an incinerator, characterized in that a control parameter is obtained based on the excess air ratio, and the amount of combustion air is controlled using the control parameter.

In the present invention, the carbon monoxide concentration detecting means or the oxygen concentration detecting means includes, for example, a semiconductor laser detector. [Action] In the combustion control method in the incinerator according to the first invention, the CO concentration in the incinerator is measured by a carbon monoxide concentration detecting means such as a semiconductor laser detector capable of instantaneously measuring the carbon monoxide concentration in the incinerator. It can be detected accurately without delay. Using this signal, the amount of secondary combustion air is calculated by PID calculation or the like so as to suppress the generation of CO. Then, the secondary combustion air amount control valve is operated so as to have the calculated secondary combustion air amount. By suppressing the generation of CO, it is possible to suppress the generation of harmful gases such as dioxin and NOx, which have a high correlation with the CO concentration.

In the combustion control method in the incinerator according to the second invention, the O ₂ concentration in the incinerator can be accurately measured without time delay by oxygen concentration detecting means capable of instantaneously measuring the oxygen concentration in the incinerator, for example, a semiconductor laser detector. Can be detected. Using this signal, the primary combustion air amount is calculated by PID calculation or the like so as to keep the O ₂ concentration constant. Then, the combustion air amount control valve is operated so as to have the calculated primary combustion air amount. By keeping the O ₂ concentration constant, dioxin,
Generation of harmful gases such as NOx can be suppressed.

In the combustion control method in the incinerator according to the third invention, the combustion state cannot be sent in time by the output of the in-furnace temperature detector, the output of the in-furnace O ₂ concentration detector, and the output of the in-furnace CO concentration detector. Can be detected accurately. Using this signal, the primary combustion air amount and the secondary combustion air amount are calculated by fuzzy calculation or the like so as to maintain the furnace temperature, the furnace O ₂ concentration, and the furnace CO concentration at appropriate values. That is, when the furnace temperature is high or the furnace CO concentration is high, the amount of primary combustion air is reduced, the gasification rate is suppressed, and the furnace CO concentration is reduced. When the furnace temperature is low or the furnace O ₂ concentration is high, the primary combustion air amount is increased, the gasification rate is increased, and the furnace O ₂ concentration is reduced. The primary combustion air amount control valve and the secondary combustion air amount control valve are operated so that the calculated primary combustion air amount and secondary combustion air amount are obtained. By maintaining the furnace temperature, the furnace O ₂ concentration, and the furnace CO concentration at appropriate values, generation of harmful gases such as dioxin and NOx can be suppressed.

In the combustion control method in the incinerator according to the fourth aspect of the invention, the combustion state in the furnace can be accurately detected without time delay by the output of the in-furnace O ₂ concentration detector and the output of the CO concentration detector. The excess air ratio in the fluidized bed is calculated using this signal. Then, control parameters of the combustion control device are calculated according to the excess air ratio. That is, when the excess air ratio in the fluidized bed is smaller than 1.0, the gain in the direction of increasing the fluidized air flow rate is small when the amount of generated steam is small, and when the excess air ratio in the fluidized bed is larger than 1.1. Decreases the gain in the direction of decreasing the fluidized air flow rate when the steam generation amount is small, and decreases the gain when the excess air ratio in the fluidized bed is greater than 1.0 to 1.1, and does not change the operating device. To do. Then, the fluidized air amount such that the steam generation amount becomes a set value based on the deviation between the calculated control parameter and the steam generation amount is operated by PID calculation or the like. Further, the fluidized air amount control valve is operated so as to have the calculated fluidized air amount.
Therefore, even when the excess air ratio in the fluidized bed greatly changes, the amount of generated steam can be kept constant.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a combustion control apparatus according to Embodiment 1.
It will be described in detail with reference to FIG. Reference numeral 1 in the figure denotes a fluidized bed furnace as an incinerator, which has a fluidized bed 2 at the bottom and a free board 3 thereon. A forced blower 6 is connected to the fluidized bed 2 via a pipe 5 having a primary combustion air amount control valve 4 interposed therebetween.

Between the pipe 5 connecting the primary combustion air amount control valve 4 and the push-in blower 6 and the free board 3, a pipe 8 having a secondary combustion air amount control valve 7 as air control means for secondary combustion interposed therebetween. Are connected by On the side wall of the free board 3, there is provided a combustion material supply hopper 9 for introducing a combustion material such as municipal waste into the fluidized bed 2. The combustion products are gasified in the fluidized bed 2 and burn on the free board 3.

In the upper stage of the free board 3, a gas cooler for cooling the exhaust gas obtained by burning the free board 3
10, an electrostatic precipitator 11 for removing particulate matter, an induction blower 12 for inducing exhaust gas, and a chimney 13 for discharging exhaust gas to the atmosphere.
Are sequentially connected.

In the middle of the free board 3, a CO concentration detector (semiconductor laser detector) using a semiconductor laser is provided.
14 are provided. The CO concentration detector 14 is a carbon monoxide concentration detecting means capable of instantaneously measuring the CO concentration in the fluidized-bed furnace. An arithmetic unit 15 is connected to the CO concentration detector 14 and the secondary combustion air amount control valve 7.

The combustion supply hopper 9 is provided with a screw conveyor 9a for extruding the combusted material supplied to the hopper 9 into the fluidized bed 2. This screw conveyor 9a
Are driven by a motor 16. On the other hand, an evaporation detector 17 for detecting the evaporation in the fluidized-bed furnace is provided above the fluidized-bed furnace 1.
Is provided. The motor 16 and the evaporation amount detector 17 are electrically connected via an arithmetic unit 18.

The operation of the fuel control device having such a configuration is as follows. First, combustion products such as municipal solid waste are put into the fluidized bed 2 of the fluidized bed furnace 1 from the combustion product supply hopper 9. The input combustion material is gasified in the fluidized bed 2 and the free board 3
Combustion. Then, the exhaust gas is cooled by the gas cooler 10, the particulate matter is removed by the electric precipitator 11, attracted by the induction blower 12, and discharged from the chimney 13 into the atmosphere.
The output X1 of the CO concentration detector 14 is input to the calculator 15. The calculator 15 calculates the secondary combustion air amount Y1 so as to suppress the generation of CO by PID calculation or the like. That is, when the CO concentration is high, the secondary combustion air amount is increased and the CO concentration is decreased. Then, the secondary combustion air amount Y calculated by the arithmetic unit 15
1 is output to the secondary combustion air amount control valve 7. The secondary combustion air amount control valve 7 adjusts the valve opening so that the set secondary combustion air flow rate Y1 is obtained. At the same time, the primary combustion air amount control valve 4 adjusts the valve opening so that the primary combustion air flow rate is set in advance even if the secondary combustion air amount changes. The output X2 of the evaporation amount detector 17 is input to the calculator 18. The calculator 18 outputs a signal Y2 in order to change the rotation speed of the screw conveyor 9a, that is, the fuel supply amount, based on the evaporation amount of the evaporation amount detector 17. Here, when the evaporation amount is low, the fuel supply amount is increased, and when the evaporation amount is high, the fuel supply amount is decreased. By the above operation, generation of CO is suppressed, and harmful gases such as dioxin and NOx are suppressed.

As described above, according to the first embodiment, the CO concentration detector using the semiconductor laser is provided in the middle stage of the free board 3.
14 and the secondary combustion air amount control valve 7 are provided,
Since the configuration is such that the CO concentration in the fluidized-bed furnace 1 is detected without a time delay and the amount of secondary combustion air is changed in accordance with the detected CO concentration, the amount and quality of the combustibles introduced into the furnace are reduced. Even if factors that disturb the combustion state inside the furnace such as fluctuations occur, the CO concentration is detected without time delay, and the secondary combustion air amount is changed so as to suppress the generation of CO, so that the correlation with the CO concentration is high. Harmful gases such as dioxin and NOx can be suppressed.

In the first embodiment, a case is described in which a single blower blows air to a fluidized bed of a fluidized bed furnace and a free board through a primary combustion air amount control valve and a secondary combustion air amount control valve, respectively. However, two push blowers may be separately provided for the primary combustion air amount control valve and the secondary combustion air amount control valve.

Embodiment 2 A combustion control device according to Embodiment 2 will be described in detail with reference to FIG. However, the same members as those in FIG. Reference numeral 21 in the figure denotes an O ₂ concentration detector using a semiconductor laser provided at the middle stage of the free board 3. The O ₂ concentration detector 14 is an O ₂ concentration detecting means capable of instantaneously measuring the O ₂ concentration in the fluidized bed furnace. Reference numeral 22 denotes a combustion air amount control valve as combustion air control means, which is provided in the middle of the pipe 5 connecting the fluidized bed 2 of the fluidized bed furnace 1 and the forced blower 6. The O ₂ concentration detector 21 and the combustion air amount control valve 22 are
Connected through. The pipe 5 near the fluidized bed 2 with respect to the combustion air amount control valve 22 and the free board 3 of the fluidized bed furnace 1
The spaces are connected by a pipe 23.

The operation of the combustion control device having such a configuration is as follows. First, combustion products such as municipal solid waste are put into the fluidized bed 2 of the fluidized bed furnace 1 from the combustion product supply hopper 9. The injected combustion material is gasified in the fluidized bed 2 and burns on the free board 3. Then, the exhaust gas is cooled by the gas cooler 10, the particulate matter is removed by the electric precipitator 11, attracted by the induction blower 12, and discharged from the chimney 13 into the atmosphere. The output X1 of the O ₂ concentration detector 21 is input to the calculator 15. Calculator 15 calculates the quantity of combustion air Y1 to maintain a constant O ₂ concentration by the PID calculation or the like. That is, when the O ₂ concentration is high, the amount of combustion air is reduced to lower the O ₂ concentration,
_{2 When the} concentration is low, the amount of combustion air is increased to increase the O ₂ concentration. Then, the combustion air amount Y1 calculated by the calculator 15 is output to the combustion air amount control valve 22. Combustion air amount control valve 22
Adjusts the valve opening degree so as to reach the set combustion air flow rate Y1. By the above operation, O ₂ concentration is kept constant,
Suppresses harmful gases such as dioxin and NOx.

As described above, according to the second embodiment, the O ₂ concentration detector using the semiconductor laser is provided in the middle stage of the free board 3.
Provided with a 21, provided combustion air amount control valve 22, O ₂
Since the concentration is detected without time delay and the amount of secondary combustion air is changed according to the detected O ₂ concentration, combustion in the furnace such as fluctuations in the quantity and quality of the combustion substances charged into the furnace Even if a factor that disturbs the state occurs, by detecting the O ₂ concentration without time delay and changing the combustion air amount so as to suppress the generation of O ₂ , dioxin having a high correlation with the O ₂ concentration,
It is possible to suppress harmful gases such as NOx.

Embodiment 3 A combustion control device according to Embodiment 3 will be described in detail with reference to FIG. However, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. Numbering 31 in the figure
Reference numeral denotes a temperature detector such as a CCD camera for detecting the temperature of a combustion portion in the fluidized-bed furnace 1.
It is provided on the upper part. The temperature detector 31 is electrically connected to the calculator 15. The computing unit 15 and the primary combustion air control valve 4 are also electrically connected.

The operation of the combustion control device having such a configuration is as follows. First, combustion products such as municipal solid waste are put into the fluidized bed 2 of the fluidized bed furnace 1 from the combustion product supply hopper 9. The injected combustion material is gasified in the fluidized bed 2 and burns on the free board 3. Then, the exhaust gas is cooled by the gas cooler 10, the particulate matter is removed by the electric precipitator 11, attracted by the induction blower 12, and discharged from the chimney 13 into the atmosphere. Output X4 output X3, CO concentration detector 14 outputs X1, O ₂ concentration detector 21 of the temperature detector 31 is input to the arithmetic unit 15. The computing unit 15 calculates the primary combustion air amount Y1 and the secondary combustion air amount Y3 so as to optimize the combustion state in the furnace by fuzzy operation or the like. That is, when the furnace temperature is high or the furnace CO concentration is high, the amount of primary combustion air is reduced, the gasification rate is suppressed, and the furnace CO concentration is reduced. When the furnace temperature is low or the furnace O ₂ concentration is high, the primary combustion air amount is increased to increase the gasification rate and increase the furnace O ₂ concentration. Then, the primary combustion air amount Y1 calculated by the arithmetic unit 15
Is output to the primary combustion air flow control valve 4. The primary combustion air flow control valve 4 adjusts the valve opening so that the set primary combustion air flow rate Y1 is obtained. The secondary combustion air flow rate Y3 calculated by the calculator 15 is output to the secondary combustion air flow control valve 7. The secondary combustion air flow control valve 7 adjusts the valve opening so that the set secondary combustion air flow rate Y3 is obtained. By the above operation, the furnace temperature, the furnace O ₂ concentration, and the furnace CO concentration are kept at appropriate values, and harmful gases such as dioxin and NOx are suppressed.

As described above, according to the third embodiment, the CO concentration detector 1 using a semiconductor laser is provided in the middle stage of the free board 3.
4. An O ₂ concentration detector 21 is provided, and a temperature detector 31 for detecting a temperature of a combustion portion in the fluidized-bed furnace 1 is provided above the free board 3 to detect a combustion state without a time delay and detect the detected combustion. Furnace temperature, furnace O ₂ concentration,
Since the primary combustion air amount and the secondary combustion air amount are changed so as to keep the CO concentration in the furnace at an appropriate value, combustion in the furnace such as fluctuations in the amount and quality of combustibles introduced into the furnace Even if a factor that disturbs the state occurs, harmful gases such as dioxin and NOx can be suppressed.

In the third embodiment, a case is described in which a single blower blows air to a fluidized bed of a fluidized bed furnace and a free board through a primary combustion air amount control valve and a secondary combustion air amount control valve, respectively. However, two push blowers may be separately provided for the primary combustion air amount control valve and the secondary combustion air amount control valve.

(Embodiment 4) A combustion control apparatus according to Embodiment 4 will be described in detail with reference to FIG. Reference numeral 41 in the figure denotes a fluidized bed furnace as an incinerator, which has a fluidized bed 42 at the bottom and a free board 43 thereon. A push blower 46 is connected to the fluidized bed 42 via a pipe 45 having a fluidized air amount control valve 44 as primary combustion air control means.

Between the pipe 45 connecting the fluidized air quantity control valve 44 and the push-in blower 46 and the free board 43, a pipe 48 interposed with a secondary combustion air quantity control valve 47 serving as secondary combustion air control means. Are connected by On the side wall of the free board 43, a combustion material supply hopper 49 for supplying a combustion material such as municipal waste into the fluidized bed 42 is provided. The combustion products are driven into a fluidized bed 42 by driving a screw conveyor 49 a by a motor 50 attached near a combustion product supply hopper 49, and are then gasified here and burned by a free board 43.

Above the free board 43, a boiler 52 provided with an evaporation detector 51, a gas cooler 53 for cooling the exhaust gas obtained by burning the free board 43, and an electric precipitator for removing particulate matter 54, an induction blower 55 for inducing exhaust gas, and a chimney 56 for discharging exhaust gas to the atmosphere are sequentially connected. The evaporation amount detector 51, the secondary combustion air amount control valve 47, the motor 50, and the fluidized air amount control valve 44 are each electrically connected to a computing unit 57.

In the middle of the free board 43, a CO concentration detector (semiconductor laser detector) using a semiconductor laser is provided.
58, an O ₂ concentration detector 59 using a semiconductor laser is provided. These CO concentration detector 58 and O ₂ concentration detector 59 are respectively a carbon monoxide concentration detecting means capable of instantaneously measuring the CO concentration in the fluidized bed furnace, and an O ₂ concentration in the fluidized bed furnace instantly. It is a possible oxygen concentration detecting means. The CO
The concentration detector 58 and the O ₂ concentration detector 59 are each connected to a fluidized air excess ratio estimator 60. A control parameter calculator 61 is electrically connected to the fluidized air excess ratio estimator 60, and the control parameter calculator 61 is electrically connected to the calculator 57.

The operation of the combustion control device having such a configuration is as follows. 1) First, combustion products such as municipal solid waste are supplied from a combustion product supply hopper 49 into the fluidized bed 42 of the fluidized bed furnace 41. The input combustion material is gasified in the fluidized bed 42 and burns on the free board 43. The boiler uses air heated by combustion.
Heat 52 to generate electricity. The exhaust gas is cooled by a gas cooler 53, and particulate matter is removed by an electric precipitator 54.
Attracted by 55 and released into the atmosphere from chimney 56. The evaporation amount detector 51 provided in the boiler 52 sends an output signal X1 of the evaporation amount to a calculator 57. The output X2 of the O ₂ concentration detector 59 and the output X3 of the CO concentration detector 58 are:
It is input to the fluidized air excess ratio estimator 60. The excess air ratio X4 in the fluidized bed estimated by the excess air ratio estimator 60 in the fluidized bed is input to the control parameter calculator 61. The control parameter calculator 61 calculates the input air excess ratio X in the fluidized bed.
Then, the control parameters of the computing unit 57 are determined based on (4).

2) That is, when the excess air ratio in the fluidized bed is smaller than 1.0, the excess air ratio in the fluidized bed is 1. When the ratio is larger than 1, when the excess air ratio in the furnace is 1.0 to 1.1, the gain is reduced so that the operating device is not fluctuated.

3) According to the calculated control parameter X5, the calculator 57 calculates the flow or air amount Y1 and the secondary combustion air amount Y such that the combustion state in the furnace is optimized by PID calculation or the like.
2 is calculated. That is, when the excess air ratio in the fluidized bed is high and the amount of generated steam is large, the amount of fluidized air is increased to cool the inside of the furnace. When the excess air ratio in the fluidized bed is high and the amount of generated steam is small, the amount of fluidized air is reduced and the furnace is heated. On the other hand, when the excess air ratio in the furnace is low and the amount of generated steam is large, the amount of fluidized air is reduced, the gasification rate is suppressed, and the amount of generated heat is reduced. When the excess air ratio in the fluidized bed is low and the amount of generated steam is small, the amount of fluidized air is increased, the gasification rate is increased, and the amount of generated heat is increased.

4) The fluidized air amount Y1 calculated by the calculator 57 is output to the fluidized air amount control valve 44. The fluidizing air amount control valve 44 adjusts the valve opening so that the fluidizing air flow rate Y1 is set. The secondary combustion air amount Y2 calculated by the calculator 57 is output to the secondary combustion air amount control valve 47.
The secondary combustion air amount control valve 47 adjusts the valve opening so that the set secondary combustion air flow rate Y2 is obtained.

As described above, according to the fourth embodiment, O ₂ in the furnace
O ₂ concentration detector 59 for detecting the concentration, the CO concentration instantaneously, C
An O concentration detector 58 is provided at the middle stage of the fluidized bed furnace 41, and an evaporation detector 51 for detecting the amount of steam generated in the boiler 52,
A fluidized air amount control valve 44 and a secondary combustion air amount control valve 47 are provided at predetermined positions, respectively, and an excess air ratio (actual air amount / theoretical air amount) in the primary combustion field is obtained by an oxygen concentration signal and a carbon monoxide concentration signal. ) Is estimated, a control parameter is obtained based on the excess air ratio, and the combustion air amount is controlled using the control parameter. Thus, other factors disturbing the quantity and quality combustion conditions such as variations furnace combustion product to be introduced into the furnace is generated, furnace O ₂ concentration, estimated fluidized bed the excess air ratio of the furnace in a CO concentration Then, the parameters of the controller are changed based on the estimated excess air ratio in the fluidized bed, and the fluidized air amount is controlled using the changed parameters, whereby the steam generation amount can be stabilized. The method of the present invention can also be applied to a stoker combustion furnace or the like.

In the fourth embodiment, a case is described in which a single blower blows air to a fluidized bed of a fluidized bed furnace and a free board through a fluidized air amount control valve and a secondary combustion air amount control valve, respectively. However, two push blowers may be separately installed for the fluidized air amount control valve and the secondary combustion air amount control valve.

[0051]

As described above in detail, according to the first aspect of the present invention, a carbon monoxide concentration detecting means capable of instantaneously measuring the carbon monoxide concentration in a furnace and a secondary combustion air control means are provided. Then, by detecting the carbon monoxide concentration without time delay, and by changing the amount of the secondary combustion air in accordance with the detected carbon monoxide concentration, the CO concentration can be accurately detected without time delay, and thus dioxin, NOx, etc. A combustion control method in an incinerator that can suppress generation of harmful gas can be provided.

According to the second aspect of the invention, there is provided an oxygen concentration detecting means capable of instantaneously measuring the oxygen concentration in the furnace and an air control means for primary combustion, and the oxygen concentration is detected without a time delay. By changing the amount of primary combustion air in accordance with the concentration, it is possible to provide a combustion control method in an incinerator that can accurately detect the O ₂ concentration without time delay and thereby suppress the generation of harmful gases such as dioxin and NOx.

According to the third aspect of the present invention, the temperature detecting means for detecting the temperature of the combustion portion in the furnace, the oxygen concentration detecting means capable of instantaneously measuring the oxygen concentration and the carbon monoxide concentration in the furnace, Equipped with carbon concentration detection means and primary and secondary combustion air control means, detects the combustion state without time delay, and uses the detected combustion state signal to determine the furnace temperature, furnace oxygen concentration, furnace monoxide. by changing the primary combustion air amount so as to maintain the concentration of carbon aptitude value and the secondary combustion air amount, furnace temperature, furnace O ₂ concentration, and accurately detecting without delay furnace CO concentration time, it has been dioxin It is possible to provide a combustion control method in an incinerator that can suppress generation of harmful gases such as NOx and NOx.

According to a fourth aspect of the present invention, an oxygen concentration detecting means and a carbon monoxide concentration detecting means capable of instantaneously measuring the oxygen concentration and the carbon monoxide concentration in the furnace, and the steam generation amount of the boiler connected to the incinerator. It comprises a detecting means for detecting and an air control means for primary and secondary combustion, and estimates an excess air ratio (actual air amount / theoretical air amount) in the primary combustion field based on the oxygen concentration signal and the carbon monoxide concentration signal. By obtaining a control parameter based on the excess air ratio and controlling the amount of combustion air using the control parameter, the output of the in-furnace O ₂ concentration detector,
It is possible to provide a combustion control method in an incinerator in which the combustion state in the furnace can be accurately detected without time delay based on the output of the CO concentration detector, and the steam generation amount can be kept constant.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a combustion control method in a combustion furnace according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a combustion control method in a combustion furnace according to Embodiment 2 of the present invention.

FIG. 3 is an explanatory diagram of a combustion control method in a combustion furnace according to Embodiment 3 of the present invention.

FIG. 4 is an explanatory diagram of a combustion control method in a combustion furnace according to Embodiment 4 of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between an excess air ratio and combustion efficiency in a combustion control method according to a fourth embodiment.

[Explanation of symbols]

1, 41: fluidized bed furnace, 2, 42: fluidized bed, 3, 43: free board, 4: primary combustion air amount control valve, 6, 46: push-in blower, 7, 47: secondary combustion air amount control valve, 9, 49 ... fuel supply hopper, 9a, 49a ... screw conveyor, 10, 53 ... gas cooler, 11, 54 ... electric dust collector, 12, 55 ... induction blower, 14, 58 ... CO concentration detector, 15, 18, 57 ... calculator, 17,51 ... evaporation amount detector, 21,59 ... O ₂ concentration detector, 31 ... temperature detector, 52 ... boiler, 60 ... fluidized bed the excess air ratio estimator, 61 ... control parameter calculation vessel.

 ──────────────────────────────────────────────────の Continued from the front page (72) Inventor Satoshi Okuno 12 Nishikicho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Heavy Industries, Ltd.

Claims (6)

[Claims] 1. The charged combustion material is gasified in a primary combustion field by primary combustion air sent from a lower part of the incinerator, and the gasified combustible gas is burned by secondary combustion air sent from a middle stage of the incinerator. A method of controlling combustion in an incinerator that suppresses the generation of toxic gases such as dioxin and NOx while maintaining the amount of heat generated by combustion irrespective of the fluctuation of the combustion material injected into the incinerator. Equipped with carbon monoxide concentration detection means and secondary combustion air control means capable of instantaneously measuring the concentration,
A combustion control method in an incinerator, characterized by detecting the concentration of carbon monoxide without a time delay, and changing the amount of secondary combustion air according to the detected concentration of carbon monoxide. 2. The charged combustion material is gasified in a primary combustion field by primary combustion air sent from a lower part of the incinerator, and the gasified combustible gas is burned by secondary combustion air sent from a middle stage of the incinerator. Irrespective of the fluctuation of the combustion material injected into the incinerator, the amount of heat generated by the combustion is kept constant and the combustion control method in the incinerator that suppresses the generation of toxic gas such as dioxin and NOx. Incineration characterized by comprising oxygen concentration detecting means and primary combustion air control means capable of instantaneously measuring, detecting the oxygen concentration without time delay, and changing the primary combustion air amount according to the detected oxygen concentration. Combustion control method in furnace. 3. The charged combustion material is gasified in a primary combustion field by primary combustion air sent from a lower portion of the incinerator, and the gasified combustible gas is burned by secondary combustion air sent from a middle stage of the incinerator. In the combustion control method in an incinerator, which keeps the calorific value of combustion constant and suppresses the generation of toxic gas such as dioxin and NOx, regardless of the fluctuation of the combustibles injected into the incinerator, Temperature detecting means for detecting a temperature,
Oxygen concentration detecting means and carbon monoxide concentration detecting means capable of instantaneously measuring each of the oxygen concentration and the carbon monoxide concentration in the incinerator;
Equipped with primary and secondary combustion air control means, detects the combustion state without time delay, and uses the detected combustion state signal to set the furnace temperature, furnace oxygen concentration, and furnace carbon monoxide concentration to appropriate values. A combustion control method in an incinerator, wherein the amount of primary combustion air and the amount of secondary combustion air are changed so as to keep them. 4. A gasified combustible gas is sent from a middle stage of the incinerator by gasifying gas in a primary combustion field in which a high-temperature fluidized medium is fluidized by fluidizing air fed from a lower portion of the incinerator. Combustion by combustion air, the combustion control method in an incinerator that controls the amount of fluidized air and the amount of fuel supply based on the deviation of the amount of generated steam. The oxygen concentration and carbon monoxide concentration in the incinerator can be measured instantaneously. Oxygen concentration detecting means, carbon monoxide concentration detecting means,
It has detection means for detecting the amount of steam generated from the boiler connected to the incinerator, and air control means for primary and secondary combustion, and the excess air ratio in the primary combustion field (actually based on the oxygen concentration signal and the carbon monoxide concentration signal). The combustion control method in an incinerator characterized by estimating the air amount / theoretical air amount), obtaining a control parameter based on the excess air ratio, and controlling the combustion air amount using the control parameter. 5. The combustion control method in an incinerator according to claim 1, wherein the carbon monoxide concentration detecting means is a semiconductor laser detector. 6. An apparatus according to claim 2, wherein said oxygen concentration detecting means is a semiconductor laser detector.
A combustion control method in the incinerator according to the above.