JP2000028123A - Secondary combustion control device of garbage incinerator - Google Patents

Abstract

(57) [Problem] To provide a target oxygen concentration for controlling the concentration of oxygen contained in exhaust gas after secondary combustion in order to simultaneously reduce the concentration of carbon monoxide and nitrogen oxide contained in exhaust gas in secondary combustion control. Provided is a secondary combustion control device for a refuse incinerator that can be operated in a short time. SOLUTION: Predetermined process data that changes according to the combustion state of a refuse incinerator 40 and oxygen concentration in exhaust gas after secondary combustion are input data, and nitrogen oxides in exhaust gas after secondary combustion in the combustion state. Exhaust gas concentration simulation means 1 using the concentration and the carbon monoxide concentration as output data, and changing the oxygen concentration as the input data within a predetermined range to determine the nitrogen oxide concentration and the carbon monoxide concentration as the output data. Target oxygen concentration setting means 2 for outputting the oxygen concentration with the lowest evaluation value as the target oxygen concentration, and setting a predetermined range of the oxygen concentration change as a part of the entire control range corresponding to the value of predetermined process data. And an oxygen concentration range setting means 3 for performing the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary combustion control device for a refuse incinerator for reducing the concentration of carbon monoxide and the concentration of nitrogen oxides in exhaust gas.

[0002]

2. Description of the Related Art Conventionally, the combustion control of a refuse incinerator has been carried out by setting an appropriate target oxygen concentration according to the combustion state and controlling the amount of secondary combustion air to maintain the target oxygen concentration. It suppresses the generation of oxides and carbon monoxide.
Therefore, as a secondary combustion control device of a garbage incinerator, a secondary combustion provided upstream of a flue for secondary combustion of flue gas discharged from a furnace having a movable grate for incineration of charged waste is provided. An air supply mechanism, a gas detection mechanism for measuring the oxygen concentration in the exhaust gas after the secondary combustion, and an air supply amount by the secondary combustion air supply mechanism to adjust the oxygen concentration detected by the gas detection mechanism to the target oxygen concentration. Is provided with an air supply amount control means for performing PID control on the air supply. Also,
As means for determining the target oxygen concentration, predetermined process data that changes in accordance with the combustion state of the refuse incinerator and the oxygen concentration are used as input data, and in the combustion state, the concentration of the nitrogen oxides in the exhaust gas after the secondary combustion. And a process model for nitrogen oxide and carbon monoxide generation using carbon monoxide concentration as output data by learning the actual data of actual furnaces using a neural network etc., and responding to changes in combustion conditions. As a method of setting an appropriate target oxygen concentration, under a specific combustion state, the predetermined process data at that time is input to the process model, and the oxygen concentration as the remaining input data is, for example, Is changed within a control range (6% to 11%) including a predetermined reference value (6% or more) indicated by Evaluating the force concentration of nitrogen oxides and carbon monoxide concentrations, there is the oxygen concentration evaluation value of the predetermined becomes minimum that has been set as the target oxygen concentration.

[0003]

In the above-described conventional secondary combustion control device for a refuse incinerator, the oxygen concentration is changed over the entire range of the preset control range every time the target oxygen concentration is set. Therefore, there is a problem that it takes a long time to perform the arithmetic processing of the process model, and it is difficult to finely adjust the target oxygen concentration.

The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems and to simultaneously reduce the concentration of carbon monoxide and the concentration of nitrogen oxide contained in exhaust gas in secondary combustion control. It is an object of the present invention to provide a secondary combustion control device for a refuse incinerator that can set a target oxygen concentration that can be reduced by a short-time calculation process and that can precisely and efficiently control a carbon monoxide concentration and a nitrogen oxide concentration. .

[0005]

Means for Solving the Problems A first characteristic configuration of a secondary combustion control device for a refuse incinerator according to the present invention for achieving this object is described in claim 1 of the claims. As shown in the figure, a secondary combustion air supply mechanism installed upstream of the flue for secondary combustion of combustion exhaust gas discharged from a furnace equipped with a mobile grate for incineration of charged waste, and exhaust gas after secondary combustion A gas detection mechanism for measuring the oxygen concentration; and an air supply control means for controlling an air supply amount by the secondary combustion air supply mechanism to adjust the oxygen concentration detected by the gas detection mechanism to a target oxygen concentration. A secondary combustion control device for a refuse incinerator, wherein predetermined process data and the oxygen concentration that change in accordance with the combustion state of the refuse incinerator are input data, and the exhaust gas content after the secondary combustion in the combustion state is included. Nitrogen oxide concentration And an exhaust gas concentration simulating means having carbon monoxide concentration as output data; and the nitrogen being an output data of the exhaust gas concentration simulating means by changing the oxygen concentration which is input data of the exhaust gas concentration simulating means within a predetermined range. Target oxygen concentration setting means for outputting, as the target oxygen concentration, an oxygen concentration at which a predetermined evaluation value of the oxide concentration and the carbon monoxide concentration is the lowest within the predetermined range, and setting the predetermined range of the oxygen concentration change to An oxygen concentration range setting means for setting as a part of the entire control range in accordance with the value of the predetermined process data is provided.

[0006] The second characteristic configuration is that, in addition to the first characteristic configuration, the refuse incinerator controls the exhaust gas temperature at the outlet of the furnace as described in claim 2 of the claims. A temperature detection mechanism for detecting the temperature of the movable grate; and a burn-off position detection mechanism for detecting a burn-off position of the movable grate. It is at the point that is the cutting position.

[0007] The third characteristic configuration may be obtained according to the combustion state of the refuse incinerator in addition to the first or second characteristic configuration, as described in claim 3 of the claims. The calculated predetermined process data is used as input data to calculate and output the appropriate oxygen concentration contained in the exhaust gas after the secondary combustion in which both the nitrogen oxide concentration and the carbon monoxide concentration in the exhaust gas after the secondary combustion are simultaneously reduced in the combustion state. The oxygen concentration range setting means sets the predetermined range such that the appropriate oxygen concentration output by the appropriate oxygen concentration calculation means is included in the predetermined range.

[0008] In a fourth feature configuration, in addition to the third feature configuration, the appropriate oxygen concentration calculating means is configured by a fuzzy inference model in addition to the third feature configuration. There is in the point.

The operation will be described below. According to the first characteristic configuration, the oxygen concentration range setting means sets the target oxygen concentration corresponding to the combustion state at that time according to the predetermined process data from the entire control range of the oxygen concentration as the predetermined range. In order to set a partial oxygen concentration range including, the target oxygen concentration setting means will change the oxygen concentration in a narrower range than the entire control range,
The processing time required for the arithmetic processing of the exhaust gas concentration simulating means and the target oxygen concentration setting means before setting the target oxygen concentration can be reduced. As a result, the target oxygen concentration can be made to closely follow the change in the combustion state, and both the nitrogen oxide concentration and the carbon monoxide concentration contained in the exhaust gas can be reduced more effectively.

By the way, the exhaust gas after the secondary combustion with respect to each of the combustion exhaust gas temperature at the furnace outlet of the existing refuse incinerator (furnace outlet temperature) and the burn-off point in the combustion zone constituting the movable grate is also shown. Examining the relationship between the oxygen content, the carbon monoxide concentration, and the nitrogen oxide concentration, the appropriate exhaust gas oxygen concentration for simultaneous reduction of the carbon monoxide concentration and the nitrogen oxide concentration depends on the furnace outlet temperature and It turns out that it changes according to the burn-off point. That is, when the furnace outlet temperature is high and when the furnace outlet temperature is low for the same burn-off area, as shown in FIG. 4, the carbon monoxide is lower when the furnace outlet temperature is lower than when the furnace outlet temperature is higher. Fig. 5 shows that the appropriate exhaust gas oxygen concentration range for reduction becomes narrower and higher as a whole, and that the burn-off point is on the upstream side and the downstream side with respect to the same furnace outlet temperature range. As shown, when the burn-off point is on the upstream side, the lower limit of the suitable exhaust gas oxygen concentration range for reducing carbon monoxide is higher than when the burn-off point is on the downstream side, and the entire suitable exhaust gas oxygen concentration range is As shown in FIGS. 4 and 5, the nitrogen oxides have a positive correlation with the exhaust gas oxygen concentration and a negative correlation with the carbon monoxide. The lower the exhaust gas oxygen concentration, the lower the nitrogen oxide concentration. By doing. That is, the combustion state in the flue has a non-linear relationship with both the furnace exit temperature condition and the burn-off position condition, and the burn-off position condition indicates the stirring and mixing conditions of the combustion exhaust gas in the furnace. It is presumed that the stirring and mixing are inadequate for the upstream side.

Therefore, according to the second characteristic configuration, the furnace exit temperature, the furnace outlet temperature,
Since the burn-off point is used, it is possible to perform secondary combustion control in which the concentrations of carbon monoxide and nitrogen oxide are simultaneously and effectively reduced. In this case, by incorporating the furnace outlet temperature into the input data, the combustion temperature conditions of the residence time (corresponding to the combustion time) in the secondary combustion area, the combustion temperature, and the stirring and mixing, which are the important conditions of the secondary combustion, are obtained. The stirring and mixing conditions are taken into account by incorporating the burn-off point into the input data. The significance of introducing the burn-off point here is that the stirring and mixing conditions of the combustion exhaust gas inside the furnace upstream of the secondary combustion area are taken into consideration, and this makes it appropriate, that is, a smaller amount of fuel gas is used. It is possible to simultaneously reduce the concentration of carbon monoxide and the concentration of nitrogen oxide by the amount of the next combustion air. The above residence time condition can be improved by design consideration of the furnace shape of the secondary combustion area.

Further, according to the third characteristic configuration, the appropriate oxygen concentration calculating means simultaneously determines both the nitrogen oxide concentration and the carbon monoxide concentration under a combustion state specified by the predetermined process data. A suitable oxygen concentration that can be reduced is determined, and the predetermined range is set so as to include the appropriate oxygen concentration without directly setting the appropriate oxygen concentration as the target oxygen concentration. However, the target oxygen concentration can be reliably obtained within the range. In the case where the appropriate oxygen concentration calculated by the appropriate oxygen concentration calculating means is directly used as the target oxygen concentration, the appropriate oxygen concentration calculating means is configured so that the appropriate oxygen concentration can be processed at high speed and with high accuracy. Although it is necessary, according to this characteristic configuration, the calculation accuracy of the appropriate oxygen concentration calculation means can be set lower than when used alone.

According to the fourth feature, the furnace outlet temperature when both the concentration of carbon monoxide and the concentration of nitrogen oxide are appropriate,
Since the relationship between the predetermined process data such as the burn-off point and the exhaust gas oxygen concentration is non-linear, the fuzzy inference effective for non-linear modeling is used for the appropriate oxygen concentration calculation means to correspond to the predetermined process data. An appropriate exhaust gas oxygen concentration can be easily estimated.

[0014]

As described above, according to the secondary combustion control system for a refuse incinerator according to the present invention, the setting of the target oxygen concentration in the secondary combustion control can be performed at high speed and with high accuracy, so that control is possible. Garbage incinerator, which can greatly reduce the carbon monoxide concentration and the concentration of nitrogen oxides contained in the exhaust gas, and which is extremely excellent in environmental protection. The present invention has an excellent effect that it is possible to prevent the processing equipment from increasing in size and to prevent a rise in equipment costs.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a garbage incinerator (plant) 40 is a movable grate 1 that burns while transporting garbage by moving stokers arranged in multiple stages back and forth.
A furnace 30 provided with an exhaust gas 4, a flue 31 for secondary combustion of the combustion exhaust gas discharged from the furnace 30, and a waste heat boiler 17 for generating steam by using heat retained by the exhaust gas from the flue 31, The exhaust gas passing through the boiler 17 is purified by an exhaust gas treatment device 18 and then exhausted from a chimney.
The municipal garbage transported in 1 is thrown into the garbage hopper 12,
The dust is supplied to the furnace 30 by a dust supply device 13 provided below the dust hopper 12. The refuse supplied to the movable grate 14 is conveyed from the upstream side to the ash pit via primary combustion air supplied from below and from the side wall, through drying, gasification, gas combustion, and solid combustion. The grate that is dried and gasified is a dry zone, the grate that is mainly solid-fired from gas combustion is the combustion zone, and the grate that is mainly incinerated from solid combustion is the post-combustion zone. A secondary combustion air supply mechanism 16 for supplying secondary combustion air to completely burn unburned harmful substances such as carbon monoxide in the combustion exhaust gas generated in the furnace 30;
A supply pipe having a secondary combustion air supply nozzle and a damper mechanism for adjusting the amount of air supplied to the nozzle is provided at the furnace outlet upstream of the flue 31. The power consumed in the facility is provided by a combined power generation system including a gas turbine generator 20 and a steam turbine generator 19 to which steam generated by the waste heat boiler 17 is supplied.

As shown in FIGS. 1 and 2, the secondary combustion control device measures the secondary combustion air supply mechanism 16 provided upstream of the flue 31 and the concentration of oxygen contained in exhaust gas after secondary combustion. A gas detection mechanism, and air supply amount control means 6 for controlling an air supply amount by the secondary combustion air supply mechanism 16 so as to adjust the oxygen concentration detected by the gas detection mechanism to a target oxygen concentration. is there.

The air supply amount control means 6 uses predetermined process data and oxygen concentration, which change in accordance with the combustion state of the refuse incinerator 40, as input data. Exhaust gas concentration simulation means 1 using the oxide concentration and the carbon monoxide concentration as output data;
A predetermined evaluation value of the nitrogen oxide concentration and the carbon monoxide concentration which are output data of the exhaust gas concentration simulating means 1 by changing the oxygen concentration which is input data of the exhaust gas concentration simulating means 1 within a predetermined range. A target oxygen concentration setting means 2 for outputting the lowest oxygen concentration within the predetermined range as the target oxygen concentration, and the nitrogen oxide concentration and the carbon monoxide in the combustion state using the predetermined process data as input data. The appropriate oxygen concentration calculating means 4 for calculating the appropriate oxygen concentration when both of the concentrations are simultaneously reduced, and the predetermined range is set so that the appropriate oxygen concentration output by the appropriate oxygen concentration calculating means 4 is included in the predetermined range. An oxygen concentration range setting means 3 that is set as a part of the entire oxygen concentration control range in accordance with the value of the predetermined process data;
The PID control unit 5 controls the air supply amount by the secondary combustion air supply mechanism 16 (that is, adjusts the opening degree of the damper) to adjust the detected oxygen concentration to the target oxygen concentration.

The predetermined process data as input data of the exhaust gas concentration simulating means 1 and the appropriate oxygen concentration calculating means 4 include an exhaust gas temperature at the outlet of the furnace 30 (hereinafter referred to as a furnace outlet temperature) and the furnace exhaust gas temperature. The burn-off position of the movable grate 14 is adopted. Therefore, a temperature detection mechanism 33 for detecting the furnace outlet temperature is provided at the outlet portion,
Further, an industrial television camera provided with a burn-off position detecting mechanism 32 for detecting a burn-off position of the movable grate 14 facing the movable grate 14 from the rear side wall of the furnace 30; Image processing of the burning flame taken by the camera,
Image processing means for extracting a position at which gas combustion shifts to solid combustion as a burn-off point; and 0% to 100% of a position between the most upstream position and the most downstream position of the combustion zone.
And an arithmetic means for outputting a numerical value of%.

Next, the operation of each part of the air supply amount control means 6 will be described. The appropriate oxygen concentration calculating means 4
Calculates the appropriate oxygen concentration sequentially using the furnace outlet temperature and the burn-off position as input data. When the appropriate oxygen concentration is input, the oxygen concentration range setting means 3 sets an oxygen concentration range for changing ± 1% around the appropriate oxygen concentration as input data of the exhaust gas concentration simulation means 1, for example. Output as Based on the oxygen concentration range set by the oxygen concentration range setting means 3, the target oxygen concentration setting means 2 sends an oxygen concentration to the exhaust gas concentration simulating means 1 at a predetermined interval from a minimum value to a maximum value. The oxygen concentration range setting means 3 outputs the oxygen concentration range setting means 3 under the conditions according to the furnace exit temperature and the burn-off position which are separately inputted and the preset operation algorithm every time the oxygen concentration is inputted. The nitrogen oxide concentration and the carbon monoxide concentration are calculated, and the results are sequentially output to the target oxygen concentration setting means 2. When the target oxygen concentration setting means 2 receives the nitrogen oxide concentration and the carbon monoxide concentration for each of the oxygen concentrations, the target oxygen concentration setting means 2 sets a predetermined evaluation value (for example,
A simple average value or a weighted average value) is calculated for each of the oxygen concentrations, and the oxygen concentration giving the minimum value is output to the PID control unit 5 as the target oxygen concentration. The PID
The controller 5 controls the amount of air supplied by the secondary combustion air supply mechanism 16 to adjust the detected oxygen concentration detected by the gas detection mechanism 34 to the target oxygen concentration by well-known PID control. In the present embodiment, the number of calculations of the exhaust gas concentration simulation means 1 required to calculate the target oxygen concentration is proportional to the width of change of the oxygen concentration. Thus, an improvement of 2.5 times can be achieved as compared with the conventional example in which the variation range of the oxygen concentration is 6% to 11%.

Since the arithmetic processing of the target oxygen concentration setting means 2 and the oxygen concentration range setting means 3 is a simple arithmetic processing, an increase in the arithmetic processing time as compared with the arithmetic processing time of the exhaust gas concentration simulating means 1 is not considered. It can be ignored. If the calculation accuracy of the appropriate oxygen concentration calculated by the appropriate oxygen concentration calculation means 4 is within ± 1% in terms of oxygen concentration, the final target concentration is set by the exhaust gas concentration simulation means 1 and the target oxygen concentration setting means 2. Since the oxygen concentration is calculated and an accurate target oxygen concentration can be obtained, the calculation time of the appropriate oxygen concentration calculating means 4 can be shortened by sacrificing the calculation accuracy to some extent, and the exhaust gas concentration simulating means 1 can be reduced. The calculation time does not increase significantly with respect to the calculation time, and the total calculation time until the final target oxygen concentration calculation can be reduced.

Incidentally, the exhaust gas concentration simulating means 1 comprises:
The process model using the furnace outlet temperature, the burn-off position, and the oxygen concentration as input variables may be configured to be processed by a computer, but in the present embodiment, the process model is configured by a known neural network. . Thereby, a highly accurate process model for a complicated process can be automatically generated by learning the neural network.

The appropriate oxygen concentration calculating means 4 uses the furnace outlet temperature and the burn-out position as input data, performs inference processing based on a predetermined fuzzy rule, and performs an appropriate exhaust gas-containing oxygen concentration after secondary combustion. Is output as output data. More specifically, as shown in FIG.
A plurality of fuzzy rules 22 having a furnace outlet temperature and a burn-off point as antecedents and a target oxygen concentration as a consequent, and fuzzy inference means 21 for calculating and deriving a required target oxygen concentration in accordance with the fuzzy rules 22. The fuzzy rule 22 is provided with an automatic adjustment mechanism 23 that automatically tunes by a neural learning using the input / output data satisfying the required combustion conditions of the actual furnace as a teacher signal.

The fuzzy rule 22 employs the Takagi-Sugeno method in which the output of the rule is represented by a linear expression of an input variable. That is, the input fuzzy variable is x ₁ (furnace outlet temperature;
3 levels of “High”, “Aptitude” and “Low”), x ₂ (Burning point;
"Upstream", "Aptitude", "Downstream") and output y
Assuming (target oxygen concentration), the rule is represented by a series of arithmetic expressions shown in Expression 1. Here, ω _{i1 and i2} are expressed by _Expression 2, and A
_i1,1 and A _i2,2 are membership functions of the antecedent part.
It is represented by the sigmoid function shown in

[0024]

## EQU1 ## if x ₁ = A _i1,1 & x ₂ = A _i2,2 th
en y = ω _{i1, i2}

Ω _{i1, i2} = a _{i1, i2} × ₁ + b _{i1, i2} × ₂ +
c _{i1, i2} ; i = 1,..., n

A _ij (x) = 1 / (1 + exp (−a (x−b)))

Finally, the fuzzy inference means 21 obtains the fuzzy inference output y ^* by the following equation (4). Here, μ _{i1 and i2} are the degrees of conformity of the antecedent part expressed by _Expression 5.

[Equation 4] y ^* = Σ (μ _{i1, i2} · ω _{i1, i2} ) / Σμ _{i1, i2}

## _EQU5 ## μ _{i1, i2} = A _i1,1 (x ₁ ) · A _i2,2 (x ₂ )

As shown in FIG. 3, the automatic adjustment mechanism 23
Is a target oxygen concentration y ^* obtained by inputting an input teacher signal 24 consisting of a furnace outlet temperature and a burn-off point determined on the basis described later to the fuzzy inference means 21, and also determined on the basis described later. The evaluation function E shown in Expression 6 representing the error from the output teacher signal 25 consisting of the oxygen concentration y ^r is represented by a neural learning, that is, a membership function and a parameter a, b and c are adjusted and calculated.

[0027]

[6] E = 1/2 · (y * -y r) 2

That is, three-dimensional input data (x ₁ , x ₂ ,
Every time y ^r ) is given, the steepest descent vector of E is obtained by partial differential operation on a, b, and c, and the calculation is repeated so that the value becomes zero. This method is the same as a general back propagation neural network learning method.

Hereinafter, another embodiment will be described. <1> In the above embodiment, the exhaust gas concentration simulation means 1
The furnace outlet temperature and the burn-off position are adopted as the predetermined process data as input data of the appropriate oxygen concentration calculating means 4, but other process data may be used. Further, by adding the ratio of the secondary combustion air flow rate to the total exhaust gas flow rate for the furnace outlet temperature and the burn-off position to the total exhaust gas flow rate to the input data, to output the exhaust gas-containing oxygen concentration after the secondary combustion, More appropriate secondary combustion air supply control becomes possible. For example, in the case of flammable garbage such as crushed garbage, incineration may be performed while squeezing the primary combustion air supplied from the lower part of the grate, in which case the concentration of carbon monoxide tends to increase. Even if the furnace outlet temperature and burn-out point are equal, the degree of carbon monoxide concentration varies depending on the supply amount of primary combustion air, so by adding the secondary combustion air flow rate ratio to the input data, Even so, effective control becomes possible.

<2> Even though the process model of the exhaust gas concentration simulating means 1 is not necessarily configured by a neural network, it is a mathematical model expressed by a general state equation using the predetermined process data as an input variable. It does not matter. Further, the fuzzy rule 22 of the appropriate oxygen concentration calculating means 4 may be a simplified fuzzy inference in which the fuzzy rule output is a real value, or may adopt a mamdani method. Further, the fuzzy rule 22 does not necessarily have to be automatically tuned by neuro-learning.

[Brief description of the drawings]

FIG. 1 is a block diagram of a refuse incinerator.

FIG. 2 is a block diagram of a secondary combustion control device of the refuse incinerator.

FIG. 3 is a block diagram of a fuzzy inference unit.

FIG. 4 is a characteristic diagram of CO and NOx concentrations with respect to exhaust gas O ₂ concentration when the furnace outlet temperature changes at a constant burn-off point.

FIG. 5 is a characteristic diagram of the CO and NOx concentrations with respect to the exhaust gas O ₂ concentration when the burn-out point changes at a constant furnace outlet temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas concentration simulation means 2 Target oxygen concentration setting means 3 Oxygen concentration range setting means 4 Appropriate oxygen concentration calculation means 5 PID control unit 6 Air supply amount control means 16 Secondary combustion air supply mechanism 30 Furnace 31 Stack 32 Detection of burn-off position Mechanism 33 Temperature detection mechanism 34 Gas detection mechanism 40 Garbage incinerator (plant)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K062 AA02 AB01 AC01 AC19 BA02 CA01 CB08 DA01 DA22 DA23 DA25 DA40 DB08 3K078 AA06 BA03 BA22 BA24 CA03

Claims (4)

[Claims] 1. A secondary combustion air supply mechanism provided upstream of a flue for secondary combustion of combustion exhaust gas discharged from a furnace provided with a movable grate for incinerating charged waste, and after secondary combustion. A gas detection mechanism for measuring the concentration of oxygen contained in the exhaust gas, and air supply amount control means for controlling an air supply amount by the secondary combustion air supply mechanism to adjust the oxygen concentration detected by the gas detection mechanism to a target oxygen concentration. A secondary combustion control device for a refuse incinerator, comprising: predetermined process data that changes in accordance with the combustion state of the refuse incinerator and the oxygen concentration as input data, and after secondary combustion in the combustion state. Exhaust gas concentration simulating means having the exhaust gas-containing nitrogen oxide concentration and carbon monoxide concentration as output data, and changing the oxygen concentration which is input data of the exhaust gas concentration simulating means within a predetermined range, Target oxygen concentration setting means for outputting, as the target oxygen concentration, an oxygen concentration at which a predetermined evaluation value of the nitrogen oxide concentration and the carbon monoxide concentration, which are output data of gas concentration simulation means, is the lowest within the predetermined range. An oxygen concentration range setting means for setting the predetermined range of the oxygen concentration change as a part of the entire control range in accordance with the value of the predetermined process data, the secondary combustion control of a refuse incinerator comprising: apparatus. 2. The refuse incinerator includes a temperature detection mechanism for detecting an exhaust gas temperature at an outlet of the furnace, and a burn-off position detection mechanism for detecting a burn-off position of the movable grate, wherein the process data Are the temperature detected by the temperature detecting mechanism and the burn-off position detected by the burn-off position detecting mechanism.
A secondary combustion control device for a garbage incinerator according to the above. 3. Using predetermined process data obtained according to the combustion state of the refuse incinerator as input data, in the combustion state, both the nitrogen oxide concentration and the carbon monoxide concentration in the exhaust gas after the secondary combustion simultaneously decrease. An appropriate oxygen concentration calculating means for calculating and outputting an appropriate oxygen concentration contained in the exhaust gas after the secondary combustion, wherein the oxygen concentration range setting means sets the appropriate oxygen concentration output by the appropriate oxygen concentration calculating means within the predetermined range. The said predetermined range is set so that it may contain.
Or the secondary combustion control device for a refuse incinerator according to 2. 4. The secondary combustion control device for a refuse incinerator according to claim 3, wherein said proper oxygen concentration calculating means is constituted by a fuzzy inference model.