JP3425707B2 - Combustion control device and method for refuse incinerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refuse incinerator and a combustion control method therefor, and more specifically, a grate incinerator is provided with a secondary combustion air supply system and a control system therefor to control the amount of secondary combustion air. Combustion in a refuse incinerator that can stabilize the temperature inside the furnace and suppress fluctuations in the oxygen (O ₂ ) concentration in the furnace, and can set the carbon monoxide (CO) concentration and NOx concentration in the combustion exhaust gas to below the reference values. The present invention relates to a control device and its method.

[0002]

2. Description of the Related Art A grate-type waste incinerator is an incinerator that is often used in a city cleaning plant. It effectively collects the enormous heat energy generated by the waste incineration process to save resources and energy. From the viewpoint of achieving the above, many of them are equipped with steam turbine power generation equipment. In the power generation by this refuse incinerator, it is necessary to maintain stable combustion, that is, the calorific value in the furnace, in order to perform stable power generation.

In this type of grate type refuse incinerator, the basic operation method is constant efficiency incineration in which a fixed amount of refuse is charged and burned at a fixed time. The method of controlling the calorific value inside the furnace at a constant level is the amount of waste that is put into the refuse incinerator at a certain time and the amount of heat generated by the put-in waste, that is, the state quantity (for example, the amount of steam) according to the combustion load. Is detected and the amount of combustion air sent to the grate of the refuse incinerator is adjusted so that it becomes stable.

FIG. 13 shows a conventional grate type refuse incinerator and its combustion control system. As shown in FIG. 1, the refuse incinerator 1 includes a grate 1a to 1c, a refuse input port 2, an ash drop port 3,
A furnace outlet 4 for discharging exhaust gas, a chimney 6, and a suction port 7 for secondary air (cooling air) are provided, and a steam generating boiler 5 equipped with a heat exchanger 5a is provided at the furnace outlet 4 for discharging exhaust gas. is set up.

The refuse incinerator 1 has a combustion air supply system for supplying cooling air to the grate 1a to 1c and a cooling air supply system for supplying cooling air into the furnace. The combustion air supply system is a fan 8 Is a supply system in which combustion air is sent to the grate 1a to 1c via a flow rate adjusting mechanism 9 such as a damper. Further, the cooling air supply system is a supply system in which the fan 10 directly sends the air from the suction port 7 into the furnace through a flow rate adjusting mechanism 11 such as a damper. A computer 17 controls opening / closing of the flow rate adjusting mechanisms 9 and 11.

The flow rate adjusting mechanism 9 comprises combustion air amount control means 1
It is controlled based on the control output value (operation amount) from 6. The amount of steam generated from the boiler 5 is measured by the steam flow meter 12, and the measured value is input to the combustion air control means 16 for calculation processing. When the steam flow rate exceeds the target value, the combustion of the flow rate adjusting mechanism 9 is performed. The air flow rate is reduced to suppress the amount of heat generated in the furnace, and the temperature inside the furnace is also reduced accordingly. When the steam flow rate is below the target value, the combustion air flow rate of the flow rate adjusting mechanism 9 is increased to increase the heat generation amount in the furnace, and the temperature in the furnace rises accordingly.

The flow rate adjusting mechanism 11 is controlled based on the control output value (operation amount) from the cooling air control means 15. It is insufficient to control the temperature in the furnace only by the combustion air supply system, and in order to further stabilize the temperature in the furnace, the temperature in the furnace is measured by the in-core thermometer 14 and the measured value is cooled. The temperature in the furnace is made constant by inputting to the air control means 15 to perform arithmetic processing and adjusting the opening of the flow rate adjusting mechanism 11 based on the output (cooling air control value).

[0008]

In the conventional grate type refuse incinerator, the control means for controlling the evaporation amount generated from the boiler mainly by operating the amount of combustion air supplied from below the grate, and the inside of the furnace And a control means for controlling the temperature in the furnace by directly supplying cooling air to the furnace. However, it is difficult to constantly control the temperature change in the furnace caused by the fluctuation of the heat generation amount of the waste and the fluctuation of the situation inside the furnace such as the distribution state of the waste layer on the grate.

Further, harmful substances discharged from the refuse incinerator, such as carbon monoxide (CO) and nitrogen oxides (NOx).
However, there is a problem that it is difficult to keep the amount of occurrence of the same low.

The present invention has been made in view of the above problems, and stabilizes the temperature inside the refuse incinerator to suppress the fluctuation range of the O ₂ concentration in the furnace, and the CO concentration in the combustion exhaust gas. , NOx concentration can be controlled to be lower than a certain value, and a combustion control device for the refuse incinerator and a method therefor are provided.

[0011]

The present invention has been made to solve the above problems, and the invention of claim 1 is
A primary combustion air supply system and a secondary combustion air supply system for supplying combustion air to the waste incinerator, and the primary combustion air supply system to the waste incinerator based on a state quantity (for example, steam quantity) according to a combustion load. Control means for operating the amount of primary combustion air supplied to the inside, first measuring means for measuring the temperature in the refuse incinerator, and second measurement for measuring the O ₂ concentration in the combustion exhaust gas of the refuse incinerator Means, third measuring means for measuring CO concentration in the combustion exhaust gas of the refuse incinerator, fourth measuring means for measuring NOx concentration in the combustion exhaust gas of the refuse incinerator, and the first to fourth measurements A non-linear control means for operating the secondary combustion air amount according to the measured value by the means ,
The nonlinear control means has a negative temperature deviation in the furnace, and
When the amount of secondary combustion air is in the cooling area, the amount of secondary combustion air
Is decreased by a certain amount, the temperature deviation in the furnace is positive, and
When the amount of secondary combustion air is in the cooling area, the amount of secondary combustion air
Is increased by a certain amount, the temperature deviation in the furnace is negative, and
If the amount of secondary combustion air is in the combustion area, the amount of secondary combustion air
Is increased by a certain amount, the temperature deviation in the furnace is positive, and
If the amount of secondary combustion air is in the combustion area, the amount of secondary combustion air
Is decreased by a certain amount, the temperature deviation in the furnace is positive, and
The amount of secondary combustion air is in the boundary area and the oxygen concentration is constant
If it is more than the value, reduce the amount of secondary combustion air by a certain amount and
The internal temperature deviation is positive and the amount of secondary combustion air is
If the oxygen concentration is less than a certain value, the secondary
The amount of combustion air is increased by a certain amount, and the temperature deviation in the furnace is negative.
And the amount of secondary combustion air is in the boundary region,
The existing secondary combustion air amount is maintained, and the oxygen concentration is set to the lower limit value.
If it is less than, increase the amount of secondary combustion air by a certain amount,
If the NOx concentration exceeds the upper limit, secondary combustion air
If the amount of CO is reduced by a certain amount and the CO concentration exceeds the upper limit,
If the secondary combustion air amount is increased by a certain amount,
It is a combustion control device for a refuse incinerator, which is characterized by adjusting the amount of burning air .

[0012]

Further, according to the invention of claim 2 , the amount of primary combustion air of the refuse incinerator is fed forward or fed back based on the state quantity according to the amount of heat generation with respect to the amount of refuse put into the refuse incinerator for a certain period of time. Operate by control,
In addition, the temperature inside the refuse incinerator and the O ₂ concentration, CO concentration, and NOx concentration in the combustion exhaust gas are measured,
The nonlinear control unit based on these measurements, the furnace temperature
Degree deviation is negative, and the amount of secondary combustion air is in the cooling area.
In some cases, the secondary combustion air amount is reduced by a certain amount to reduce the furnace temperature.
Degree deviation is positive, and the amount of secondary combustion air is in the cooling area.
If there is, increase the secondary combustion air amount by a certain amount to increase the furnace temperature.
Degree deviation is negative, and the amount of secondary combustion air is in the combustion region.
If there is, increase the secondary combustion air amount by a certain amount to increase the furnace temperature.
Degree deviation is positive, and the amount of secondary combustion air is in the combustion region.
In some cases, the secondary combustion air amount is reduced by a certain amount to reduce the furnace temperature.
Degree deviation is positive and the amount of secondary combustion air is in the boundary area.
Yes, and if the oxygen concentration is above a certain level, secondary combustion
The amount of air is reduced by a certain amount , the temperature deviation in the furnace is positive, and
Second, the amount of secondary combustion air is in the boundary region, and the oxygen concentration is
Is less than a certain value, the secondary combustion air amount is increased by a certain amount.
Therefore, the temperature deviation in the furnace is negative, and the amount of secondary combustion air is
If it is in the boundary area, the current secondary combustion air amount is retained.
If the oxygen concentration falls below the lower limit setting value, secondary combustion
Increase the amount of air by a certain amount and the NOx concentration exceeds the upper limit.
If it is, the amount of secondary combustion air is reduced by a certain amount to reduce CO concentration.
If the temperature exceeds the upper limit, the amount of secondary combustion air remains constant.
A combustion control method for a refuse incinerator, which is characterized in that the amount of secondary combustion air is manipulated so as to increase the amount .

[0014]

[0015]

The outline of the present invention will be described below.
The primary combustion air control system includes a primary combustion air supply system for supplying primary combustion air to the grate of the refuse incinerator, a secondary combustion air supply system for supplying secondary combustion air into the furnace, and a control system for them. Controls the amount of heat generated by combustion based on the state quantity according to the combustion load, and secondarily stabilizes the temperature inside the furnace, and
The secondary combustion air is operated by the non-linear control means to control the furnace temperature and the O ₂ concentration, CO concentration, and NOx concentration of the combustion exhaust gas so as to be within the predetermined ranges.

According to the present invention, as for the relationship between the in-furnace temperature and the secondary combustion air amount, as shown in FIG. 4, the region in which the in-furnace temperature has a positive correlation characteristic with the secondary combustion air amount and the negative correlation characteristic. And has a characteristic that the maximum value is obtained between the two regions (for example, the secondary combustion air amount is 4000 to 5000 Nm ³ / h). In the region with a positive correlation, the unburned components in the exhaust gas generated by primary combustion undergo secondary combustion, and the secondary combustion becomes more active as the amount of secondary combustion air increases. It has a positive relationship with the internal temperature. On the other hand, when the unburned component in the exhaust gas due to the primary combustion is burned out, the secondary combustion air beyond that functions as cooling air, which has a negative relationship. or,
As shown in FIG. 5, the O ₂ concentration in the combustion exhaust gas has a positive correlation characteristic with the secondary combustion air amount. Further, as shown in FIG. 6, the CO concentration increases as the secondary combustion air amount decreases and the oxygen concentration in the furnace becomes insufficient to increase the CO concentration. Further, the NOx concentration in the combustion exhaust gas has a positive correlation characteristic with the amount of secondary combustion air, as shown in FIG.

From this point of view, the temperature in the furnace and the O ₂ concentration, CO concentration, and NOx concentration in the exhaust gas are measured, and the nonlinear control is performed according to the above-mentioned internal combustion temperature characteristic and exhaust gas characteristic with respect to the secondary combustion air amount ( For example, fuzzy control) to control the secondary combustion air amount more finely to control both the furnace temperature and the O ₂ concentration in the furnace in a stable state, and to reduce the CO concentration and NO _X concentration in the exhaust gas. The value is controlled to be lower than a predetermined value. That is, the furnace temperature was controlled to follow a predetermined control target value by feedback control or feed forward control of the primary combustion air amount, further, O ₂ concentration, C
Since the O concentration and the NOx concentration have a significant correlation with the secondary combustion air amount, the secondary combustion air amount is nonlinearly controlled to improve the response characteristics, and the O ₂ concentration, the CO concentration, and the NOx concentration are This is a combustion control method for a refuse incinerator that can be finely controlled by control target values. Further, this non-linear control uses the temperature inside the furnace and the O ₂ concentration, CO concentration, and NOx concentration in the exhaust gas as the measured values, and the secondary combustion air amount as the manipulated variable to increase and decrease by condition.
It was realized by control .

[0019]

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 diagram showing an embodiment of a refuse incinerator and a combustion control method therefor according to the present invention. FIG. 1 shows a grate-type waste incinerator 1, which has a grate 1
a to 1c, a dust input port 2, an ash drop port 3, a furnace outlet 4 for discharging combustion exhaust gas, a steam generation boiler 5 near the furnace outlet 4, a chimney 6 for discharging combustion exhaust gas to the outside of the furnace, and a secondary An intake port 7 is provided to which combustion air is supplied.

The waste introduced into the refuse incinerator 1 through the waste inlet 2 is incinerated through the drying and combustion stages by the primary combustion air blown up from under the grate 1a to 1c, and the ash is dropped from the ash drop inlet 3 into ash. It is discharged outside the furnace. Further, secondary combustion air is supplied from the suction port 7 into the furnace to control the temperature inside the furnace and the O ₂ concentration, CO ₂ concentration and NOx concentration in the exhaust gas.

The combustion exhaust gas generated by combustion is the furnace outlet 4
Is led to the chimney 6 and discharged outside the furnace. At that time, the high-temperature combustion exhaust gas heats the heat exchanger 5a to heat the boiler 5
The water inside is boiled and the steam is used for heat supply and power generation.

This refuse incinerator 1 is provided with a combustion air supply system of two systems of primary combustion air and secondary combustion air, and the primary combustion air supply system is a grate from a fan 8 through a flow rate adjusting mechanism 9 such as a damper. The secondary combustion air supply system is a system for sending combustion air to 1a to 1c, and the secondary combustion air supply system directly sucks the secondary combustion air from a fan 10 via a flow rate adjusting mechanism 11 such as a damper.
It is a system that blows into the furnace from.

The primary and secondary combustion air is stored in the computer 2
According to the control values from the primary combustion air control means 16 and the secondary combustion air control means 20, the flow rate adjusting mechanisms 9 and 11
Are controlled by opening and closing, and their flow rates are set. The primary combustion air control system controls the steam flow rate of the boiler 5 by the steam flow meter 12
In the control system, the primary combustion air control means 16 performs arithmetic processing on the measured value to control the opening / closing of the flow rate adjusting mechanism 9. Further, the secondary combustion air control system detects the temperature inside the furnace by the temperature sensor 13 inside the furnace, and detects the temperature inside the furnace outlet 4.
The O ₂ concentration and NOx in the exhaust gas are respectively measured by the ₂ concentration sensor 18, the NOx concentration sensor 22, and the CO concentration sensor 24.
Concentration and CO concentration are respectively detected, and their outputs are respectively measured in the furnace temperature meter 14, the furnace exhaust O ₂ concentration meter 19, and the furnace discharge N.
It is input to the Ox concentration meter 23 and the furnace exhaust CO concentration meter 25, these measured values are input to the secondary combustion air control means 20 and arithmetic processing is performed, and the opening / closing control of the flow rate adjusting mechanism 11 is performed based on these measured values. .

Next, the control system of the primary combustion air control means 16 and the secondary combustion air control means 20 will be described with reference to the control blocks of FIGS. FIG. 2 is an implementation of the present invention .
The primary combustion air control means for stabilizing the amount of steam , which corresponds to the form, has a furnace temperature, a furnace O ₂ concentration stabilization, and a furnace discharge N.
O ₂ concentration, a control system that combines the secondary air control means for the secondary combustion air control was Conditional decrease control for suppressing the CO concentration, Figure 3 corresponds to the reference example, the secondary air control the same purpose This is a case where the means is a fuzzy control system.

FIG. 2 shows the primary combustion air control means 16.
The primary combustion air amount is proportional to the feed-forward or feedback in the primary combustion air amount control unit A1 due to the steam amount difference between the target amount of steam and the amount of steam obtained from the combustion process A2 of the refuse incinerator. Integral control is performed, and the amount of steam is controlled by operating the amount of primary combustion air blown into the combustion process A2 of the refuse incinerator by the output value of the primary combustion air control.

In the primary combustion air amount control section A1, the primary combustion air control output value F1 is calculated based on the arithmetic expression shown in the equation (1).

[0027]       F1 = (100 / PB) × (1 + 1 / Tis) × (STMset−STMnow) …… (1)

(However, F1 is the primary combustion air control output value, ST
Mset is the target steam amount and STMnow is the measured steam amount. Further, PB is a proportional parameter, Ti is an adjustment parameter representing an integral gain, and s represents a Laplace operator. )

The opening of the flow rate adjusting mechanism 9 for controlling the primary combustion air amount is adjusted by the primary combustion air control output value F1 calculated by the equation (1), and the primary combustion air amount supplied into the furnace is adjusted. Controlled.

Further, in the secondary combustion air control means 20, the furnace temperature deviation value between the furnace temperature from the combustion process A2 of the refuse incinerator and the furnace temperature target value, the furnace exhaust O ₂ concentration and the furnace exhaust O ₂
The secondary combustion air amount control unit A3 is obtained by comparison with the set value related to the concentration, comparison between the furnace exhausted NOx concentration and the furnace exhausted NOx concentration set value, and comparison between the CO concentration value and the CO concentration set value.
In accordance with the conditions, the increase / decrease control is performed for each condition, and the in-furnace temperature of the combustion process A2 of the refuse incinerator and the O ₂ concentration, NOx concentration, and CO concentration of the exhaust gas are controlled by the output value of the secondary combustion air control.

Next, the control method of the secondary combustion air amount control section A3 will be described in more detail. The embodiment of FIG. 2 is a condition-based increase / decrease control. Before the explanation, the furnace temperature, O ₂
The relationship between the concentration, the CO concentration, the NOx concentration and the secondary combustion air amount will be described in detail with reference to FIGS. 4 to 7.

As is apparent from FIG. 4, the secondary combustion air has a secondary combustion region functioning as secondary combustion air and a cooling region acting as cooling air. The secondary combustion region is a region of less than 4000 Nm ³ / h, and this combustion region is a region where the secondary combustion is activated and the temperature in the furnace rises. Furthermore, as the amount of secondary combustion air increases, approximately 400
In the region of 0 to 5000 Nm ³ / h, the temperature rise in the furnace due to the amount of secondary combustion air reaches the maximum region. Furthermore,
The amount of secondary combustion air increases, for example, 5000 Nm ³ / h
With the above, there is a cooling region where the temperature inside the furnace decreases.

The relationship between the O ₂ concentration in the exhaust gas and the amount of secondary combustion air is as shown in FIG. 5, as the O ₂ concentration in the exhaust gas increases as the amount of secondary combustion air increases, There is a positive correlation between the amount of combustion air and the O ₂ concentration.

Further, as shown in FIG. 6, the relationship between the CO concentration in the exhaust gas and the secondary combustion air amount is such that the CO concentration in the exhaust gas decreases as the secondary combustion air amount increases, and the secondary combustion air amount decreases. There is a negative correlation between amount and CO concentration.

As shown in FIG. 7, the relationship between the NOx concentration in the exhaust gas and the secondary combustion air amount is such that the NOx concentration in the exhaust gas increases as the secondary combustion air amount increases, and the secondary combustion air amount increases. There is a positive correlation between the amount and the NOx concentration.

By utilizing such a phenomenon, the amount of secondary combustion air
The controller A3 controls the amount of secondary combustion air. Secondary combustion air
Whether the furnace temperature deviation is negative or positive in the quantity control unit A3
Is determined by a predetermined deviation value, and the amount of secondary combustion air is
(For example, the threshold value is 4000 Nm ³/ H)), border
Boundary region (for example, 4000 to 5000 Nm³/ H and setting
Constant) or cooling area (for example, a threshold of 5000 Nm³/ H
It is judged whether it is in the above and setting) and judge those two conditions
Whether the secondary combustion air amount should be increased or decreased from the result of
Perform another increase / decrease control.

Further, it is judged whether or not the NOx concentration and the CO concentration exceed the upper limit values. If the NOx concentration exceeds the upper limit value, the secondary combustion air amount is reduced by a certain amount and the CO concentration exceeds the upper limit value. If so, the secondary combustion air amount is adjusted so as to be increased by a fixed amount, and control is performed so as to suppress an increase in NOx concentration and CO concentration.

The control method of the secondary combustion air amount control section A3 for controlling the secondary combustion air amount will be described in detail below with reference to Table 1. The secondary combustion air amount is calculated and detected sequentially under the conditions (1) to (10), and when the conditions (8) to (10) are satisfied, the control indicated by the arrow (->) is executed sequentially. To do.

[0039]

[Table 1]

The control methods shown in Table 1 are (1)-
(6) is a control process for increasing or decreasing the secondary combustion air amount for the temperature deviation in the furnace, and a control process for adjusting the increment or decrement of the constant value of the secondary combustion air for each cycle. . (7) shows the control process for maintaining the current amount of secondary combustion air. (8) is for controlling the oxygen concentration, (9) is for the NOx concentration upper limit set value, and (10) is the control process for the CO concentration upper limit set value. These controls can be set individually.

Next, the calculation method of the secondary combustion air amount control unit (secondary combustion air control means 20) will be described based on the flow chart of FIG. The measured values from the controlled object are sampled at regular intervals, and the secondary combustion air amount is controlled based on those measured values. 12 (a)-
(D) is a flow chart showing a concrete control method of the secondary combustion air amount shown in Table 1. In these flow charts, each control method (1) to (10) in Table 1 is ) ~(Ten)
Is illustrated as.

FIG. 12A shows each control method (1)-
The control method for calculating (7) is shown in FIG. 12 (b), which is the control method in Table 1 (8), and in FIG. 12 (c), which is the control method in Table 1.
(9) and FIG. 12 (d) show the control method (10) in Table 1. 12A to 12D show start1, start2, start3.
Then, control is started from start4 and start4, and it is determined whether each condition is satisfied according to the flowchart, and the final adjustment parameter (z1
~ Z4) values are determined. The secondary combustion air amount output value is calculated from the previous value of the secondary combustion air amount output value (F2 (k−1)) and the adjustment parameter z1 to z4 as shown in the following equation. Current value (secondary combustion air control amount in a certain cycle)
(F2 (k)) has been calculated.

[0043]               F2 (k) = F2 (k-1) ＋ z1 ＋ z2 ＋ z3 ＋ z4 ………………… (2)

The adjustment parameters z1 to z4 are shown in FIG.
It is calculated based on the flow chart of (d). 12
In (a) to (d), Te is the temperature deviation in the furnace, F2now is the secondary combustion air amount, O2 is the oxygen concentration, NOx is the NOx concentration, and CO is the CO concentration. Further, C ₁ and C ₂ are adjustment parameters for distinguishing the combustion region, the boundary region, and the cooling region by the secondary combustion air amount. Ox1 is an adjustment parameter for determining the upper limit setting value of oxygen concentration, Ox2 is an adjustment parameter for determining the lower limit setting value of oxygen concentration, NOx1 is an adjustment parameter for determining the upper limit setting value of NOx concentration, and CO1 is It is an adjustment parameter for determining the upper limit set value of the CO concentration. y1 to y10 are increments of the secondary combustion air amount,
This is an adjustment parameter that gives a decrement amount.

Explaining FIG. 12A, first,
In step S1, the temperature deviation Te in the furnace is controlled by the control condition (Te <
0), and if the control condition (Te <0) is satisfied, the process proceeds to step S2. In step S2, when the secondary combustion air amount satisfies the control condition (F2now ≧ C ₂ ), the adjustment parameter z1 is set to y1. If the control condition (F2now ≧ C ₂ ) of step S2 is not satisfied, step S3
Then, the control condition (F2now ≤ C ₁ ) is determined. If the control condition (F2now ≤ C ₁ ) is satisfied, the adjustment parameter z1
Is set to y3, and when the control condition (F2now ≤ C ₁ ) is not satisfied, the adjustment parameter z1 is set to y7. When the control condition (Te <0) of step S1 is not satisfied, the process proceeds to step S4. When the control condition (F2now ≧ C ₂ ) of step S4 is satisfied, the adjustment parameter z1 is set to y2, and the control condition (F2
If now ≧ C ₂ ) is not satisfied, the process proceeds to step S5.
At step S5 control conditions (F2now ≦ C ₁₎ is determined, when satisfied with the adjustment parameter z1 and y4, it is not satisfied the control condition (F2now ≦ C ₂₎ Step S
Go to 6. In step S6, the control condition (O2 ≧ Ox1)
When the control condition is satisfied, the adjustment parameter z1 is set to y5, and when the control condition is not satisfied, the adjustment parameter z1 is set to y6.

FIG. 12B is a flow chart showing the control of the secondary combustion air amount by the oxygen concentration. The oxygen concentration O2 measured in a predetermined cycle is the lower limit setting value Ox2 of the oxygen concentration.
The control condition (O2 <
Ox2), and if this control condition is satisfied, the adjustment parameter z2 is set to y8, and if it is not satisfied,
The adjustment parameter z2 is zero. FIG. 12C shows NOx.
It is a flow chart which shows control of the amount of secondary combustion air by concentration. The NOx concentration NOx1 measured in a predetermined cycle is determined by a control condition (NOx> NOx1) for determining whether the NOx concentration is higher than the upper limit set value NOx1 of the NOx concentration. If this control condition is satisfied, adjustment is made. If the parameter z3 is set to y9 and it is not satisfied, the adjustment parameter z3
Is 0. FIG. 12D is a flow chart showing the control of the secondary combustion air amount according to the CO concentration. A control condition (CO> C) for determining whether or not the CO concentration measured in a predetermined cycle is higher than the CO concentration upper limit set value CO1.
If it is determined by O1) and this control condition is satisfied, the adjustment parameter z4 is set to y10, and if not satisfied, the adjustment parameter z4 is set to 0.

The values of the adjustment parameters z1 to z4 calculated according to the flowchart of FIG. 12 are substituted into the equation (2) to calculate the secondary combustion air amount output value F2 (k).

Next, a reference example will be described. This reference
In the example , the secondary combustion air amount control A3 is fuzzy control,
A description will be given based on the control block of FIG. The rules for fuzzy control are shown in Table 2.

[0049]

[Table 2]

FIG. 8 illustrates rules (1) to (10) in Table 2, and the operations of these rules (1) to (10) are performed by the antecedent part membership function shown in FIG. Is based on. The inference result of the consequent part of each rule obtained by the secondary air amount control means 20 is integrated, and the inference result of the entire rule (secondary combustion air amount control value) is output. The flow rate adjusting mechanism 9 is adjusted based on this control output value to control the amount of secondary combustion air. For integrating the consequent inference results of each rule, a general method of fuzzy operation, for example, min-max
The centroid method or the product-sum centroid method is used.

In addition, when the calculation results of the rules (1) to (10) in Table 2 do not satisfy the conditions, the output is set to zero, and the calculation results of the rules (1) to (10) are The amount of change in the secondary combustion air amount is calculated by the sum of the calculation results, and the secondary combustion air amount is adjusted. The operations of these rules (1) to (10) are continuously obtained.

Incidentally, in the rules (4) and (8), the calculated value of the change in the secondary air amount in the mutually opposite directions is calculated. Therefore, the secondary combustion air amount is manipulated so that the final output increases or decreases the secondary combustion air amount or maintains the current state according to the added value.

A calculation method of the control unit of the secondary combustion air when a specific fuzzy control is applied will be described by using the antecedent part membership function of FIG. First, the suitability of the antecedent part is calculated. The measured value Te of the temperature deviation in the furnace is a ₁ in the membership function of the antecedent part of FIG. 9A, which is a ₁ in conformity with the condition “the temperature deviation in the furnace is negative”. Similarly, the goodness of fit is a ₂ for “zero” and the goodness of fit is a ₃ (“0”) for “positive”. In the membership function of the antecedent part of FIG. 7B, the measured value at the furnace outlet O ₂ concentration is O ₂ , and the degree of conformity to the condition “high” is b ₁
(“0”), and the matching degree is “b” for b
₂ (“1”), the degree of conformity to “low” is b ₃ (“0”)
Is. For the current value of secondary combustion air amount, see Figure (c).
In the antecedent part membership function of, the measured value is F2now
The fitness for the condition of “small” is c ₁ , the fitness for “middle” is c ₂ , and the fitness for “large” is c ₃ (“0”). The furnace outlet NOx concentration, the antecedent membership function in FIG. (D), the measured value is NOx, fit for the condition of "high" is d _1, fit to "relevant" is d _{Is 2} . Regarding the CO concentration at the furnace outlet, the measured value is CO in the membership function of the antecedent part of FIG.
The goodness of fit for the “high” condition is e ₁ (“0”), and the goodness of fit for “adequate” is e ₂ (“1”).

Then, the conformance X ₁ is calculated by the equation (3) according to the rule (1) of FIG. The rule (1) is "fitness a ₁ and c ₃ " because "the temperature deviation in the furnace is negative and the secondary combustion air amount present value is large". Similarly, the goodnesses of fit X _{2 to} X ₈ for the rules (2) to (10) are calculated by the following formulas (4) to (12).

[0055]

[Formula 1] Goodness of fit of rule (1) X ₁ = a ₁ × c ₃ ………… (3) Goodness of fit of rule (2) X ₂ = a ₃ × c ₃ ………… (4) Rule ( Goodness of fit of 3) X ₃ = a ₁ × c ₁ ………… (5) Goodness of fit of rule (4) X ₄ = a ₃ × c ₁ ………… (6) Goodness of fit of rule (5) X ₅ = a ₃ × c ₂ × b ₁ ………… (7) Goodness of fit of rule (6) X ₆ = a ₃ × c ₂ × b ₂ ………… (8) Goodness of fit of rule (7) X ₇ = a ₁ × c ₂ ………… (9) Goodness of fit of rule (8) X ₈ ＝ d ₁ ………… (10) Goodness of fit of rule (9) X ₉ ＝ e ₁ ………… ( 11) Goodness of fit of rule (10) X ₁₀ = b ₃ ………… (12)

Next, in the consequent part membership function, in order to make an inference, the secondary combustion air amount changes Y _{1 to} Y
Determine ₁₀ Then, the inference is performed by the following equation (11) and the inference result Z is obtained.

[0057]

[Equation 2]

Finally, the present value (F2 (k)) of the secondary combustion air amount output value is obtained from the inference result Z and the previous value (F2 (k-1)) of the secondary fuel air amount output value from the inference result.

[0059]       F2 (k) = F2 (k-1) + Z ............ (14)

FIG. 11 shows an example of a control test result by the control method of the refuse incinerator according to the present invention.
0 shows the result by the conventional proportional control method of the refuse incinerator.

As is clear from these figures, as a result of applying the present invention, the average value of NOx concentration in exhaust gas is 100 p
It was possible to reduce the pm level to 70 ppm level, which is about 30 ppm. On the other hand, in the case of CO concentration, C
The peak of O concentration mainly occurs due to the temperature decrease in the furnace,
By suppressing the temperature change width in the furnace by about 25%, the temperature decrease in the furnace was less likely to occur, and in the present invention, the CO concentration peak generation was suppressed, and the flat characteristics could be obtained. Further, the fluctuation range of the O ₂ concentration could be reduced by about 30%, and a very satisfactory result was obtained. In this embodiment,
Although the temperature deviation in the furnace is used as an input to the control system for the secondary combustion air amount, when the waste incinerator is equipped with a boiler,
The steam flow rate deviation may be used instead of the furnace temperature deviation.

[0062]

As described above, according to the present invention,
Secondary combustion air amount nonlinear control, in particular, furnace temperature, the furnace O ₂ concentration stabilized by Rukoto Gyosu Conditional decrease system of secondary combustion air amount, and, CO concentration in the exhaust gas, NOx concentration Is controlled to a predetermined value, the harmful components in the exhaust gas can be controlled to a predetermined value or less, and the life of the refuse incinerator can be extended. Further, since the temperature inside the furnace can be stabilized, it has the effect of stabilizing the amount of steam in the boiler, and the energy of exhaust gas can be effectively used.

Further, when the temperature in the furnace is too low, although there is a sufficient oxygen concentration in the furnace, secondary combustion becomes difficult to occur, and the CO concentration in the exhaust gas increases. If it is possible to detect that the secondary combustion air amount is in the cooling region from the O ₂ concentration in the exhaust gas that is correlated with the secondary combustion air amount, the secondary combustion air amount is decreased to raise the temperature in the furnace, There is an advantage that the increase of CO concentration in exhaust gas can be prevented.

Further, according to the present invention, the fluctuation range of the O ₂ concentration in the exhaust gas is suppressed, and when the CO concentration and the NOx concentration increase, the secondary combustion is dealt with to cancel the increase in the concentration. by adjusting the air amount, prevention of increase in exhaust CO concentration due to incomplete combustion due to a decrease in O ₂ concentration, or increase in emission NOx concentration by the O ₂ concentration increase can be advantageously prevented.

Even if there is a change in the calorific value of the waste that is put into the waste incinerator, the temperature inside the furnace and the O _{2 in the} exhaust gas
Since both the concentrations are controlled in a stable state, there is an advantage that combustion can always be performed with good combustion efficiency. Therefore, in the grate type refuse incinerator equipped with a boiler for power generation and the like, the calorific value is stabilized, so that the power generation efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a combustion control device for a refuse incinerator and a method therefor according to the present invention.

FIG. 2 is a control block diagram of a combustion control method.

FIG. 3 is a control block diagram of a combustion control method by fuzzy control.

FIG. 4 is a diagram showing a relationship between a furnace temperature and an amount of secondary combustion air.

FIG. 5 is a diagram showing the relationship between the O ₂ concentration in exhaust gas and the amount of secondary combustion air.

FIG. 6 is a diagram showing the relationship between the CO concentration in exhaust gas and the amount of secondary combustion air.

FIG. 7 is a diagram showing the relationship between the NOx concentration in exhaust gas and the amount of secondary combustion air.

FIG. 8 is a diagram showing an antecedent part (input) and a consequent part (output) of fuzzy control.

FIG. 9 is a diagram showing an antecedent part membership function.

FIG. 10 is a diagram showing a control test result of CO concentration and NOx concentration by a conventional refuse incinerator.

FIG. 11 C by the combustion control device of the refuse incinerator of the present invention
It is a figure which shows the control test result of O concentration and NOx concentration.

FIG. 12 is a flowchart illustrating an embodiment of a combustion control device for a refuse incinerator and a method thereof according to the present invention.

FIG. 13 is a diagram showing a conventional refuse incinerator and its combustion control method.

[Explanation of symbols]

1 Garbage Incinerator 1a to 1c Grate 2 Garbage Inlet 3 Ash Drop Out 4 Furnace Outlet 5 Boiler 6 Chimney 7 Inlet 8,10 Fan 9,11 Flow Control Mechanism (Damper) 12 Steam Flow Meter 13 In-Temperature Sensor 14 In-furnace thermometer 16 Primary combustion air control means 18 O ₂ concentration sensor 19 Reactor exhaust O ₂ concentration meter 20 Secondary combustion air control means 21 Computer 22 NOx concentration sensor 23 Reactor exhaust NOx concentration meter 24 CO concentration sensor 25 Reactor exhausted CO concentration Total

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-332501 (JP, A) JP-A-6-31299 (JP, A) JP-A-5-196220 (JP, A) JP-A-62- 169920 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F23G 5/50 ZAB F23G 5/14 ZAB F23G 5/46 ZAB

Claims (2)

(57) [Claims] 1. A primary combustion air supply system and a secondary combustion air supply system for supplying combustion air to the refuse incinerator, and the primary combustion air supply system to the inside of the refuse incinerator based on a state quantity according to a combustion load. Control means for operating the amount of primary combustion air supplied to the waste incinerator, first measuring means for measuring the temperature in the waste incinerator, and second measuring means for measuring the O ₂ concentration in the combustion exhaust gas of the waste incinerator. And third measuring means for measuring the CO concentration in the combustion exhaust gas of the refuse incinerator, and fourth measuring means for measuring the NOx concentration in the combustion exhaust gas of the waste incinerator,
Non-linear control means for operating the secondary combustion air amount according to the measurement values of the first to fourth measuring means , wherein the non-linear control means has a negative furnace temperature deviation, and the secondary combustion air amount is cooling
If it is in the region, the secondary combustion air amount is reduced by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is cooled.
In the range, the secondary combustion air amount is increased by a certain amount, the furnace temperature deviation is negative, and the secondary combustion air amount is burned.
In the range, the secondary combustion air amount is increased by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is burned.
In the region, the secondary combustion air amount is reduced by a certain amount, the furnace temperature deviation is positive, and the secondary combustion air amount is the boundary.
If it is in the region and the oxygen concentration is above a certain level,
The secondary combustion air amount is reduced by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is the boundary.
If the oxygen concentration is less than a certain value,
The secondary combustion air amount is increased by a certain amount , the temperature deviation in the furnace is negative, and the secondary combustion air amount is the boundary.
If it is in the range, the current amount of secondary combustion air is maintained, and if the oxygen concentration is below the lower limit setting value, the secondary combustion air is maintained.
If the NOx concentration exceeds the upper limit by increasing the amount by a certain amount , the secondary combustion air
If the CO concentration exceeds the upper limit value, the amount of secondary combustion air is reduced.
The secondary combustion air amount so that
That the combustion control system of the incinerator, characterized in that. 2. Garbage that is put into a refuse incinerator for a certain period of time
Based on the state quantity according to the calorific value relative to the quantity
Feedforward control of the primary combustion air volume of the incinerator
Operate by feedback control and
Reactor internal temperature, O ₂ concentration in combustion exhaust gas , CO concentration
Degree and NOx concentration are measured respectively, and these measured values are
Based on the nonlinear control means , the temperature deviation in the furnace is negative and the amount of secondary combustion air is cooled.
If it is in the region, the secondary combustion air amount is reduced by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is cooled.
In the range, the secondary combustion air amount is increased by a certain amount, the furnace temperature deviation is negative, and the secondary combustion air amount is burned.
In the range, the secondary combustion air amount is increased by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is burned.
In the region, the secondary combustion air amount is reduced by a certain amount, the furnace temperature deviation is positive, and the secondary combustion air amount is the boundary.
If it is in the region and the oxygen concentration is above a certain level,
The secondary combustion air amount is reduced by a certain amount , the temperature deviation in the furnace is positive, and the secondary combustion air amount is the boundary.
If the oxygen concentration is less than a certain value,
The secondary combustion air amount is increased by a certain amount , the temperature deviation in the furnace is negative, and the secondary combustion air amount is the boundary.
If it is in the range, the current amount of secondary combustion air is maintained, and if the oxygen concentration is below the lower limit setting value, the secondary combustion air is maintained.
If the NOx concentration exceeds the upper limit by increasing the amount by a certain amount , the secondary combustion air
If the CO concentration exceeds the upper limit value, the amount of secondary combustion air is reduced.
Manipulate the amount of secondary combustion air so that
A combustion control method for a refuse incinerator, which is characterized by the above.