Furnace control method and device

Abstract

To provide a control method for a furnace that enables reaction between nitrogen oxide and reducing gas within the furnace, that is denitration within the furnace.SOLUTION: In a control method for a furnace having a primary combustion chamber 11 that performs primary combustion and a secondary combustion chamber 12 that performs secondary combustion of an unburned portion after the primary combustion, in the secondary combustion chamber 12 or on a downstream side of the secondary combustion chamber 12, a concentration distribution of nitrogen oxide and / or a concentration distribution of nitrogen oxide correlated gas correlated with concentration of nitrogen oxide is measured, and a concentration distribution of reducing gas for reducing nitrogen oxide and / or a concentration distribution of reducing gas correlated gas correlated with a concentration of the reducing gas is measured. On the basis of these concentration distributions, at least one of a secondary combustion air amount, a stirring gas amount for stirring gas in the secondary combustion chamber 12, a primary combustion air amount, a feeding speed of a fuel supply device 6 and a feeding speed of a fire grate 7 is controlled.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for controlling a furnace having a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned fuel after the primary combustion. [Background technology]

[0002] Some furnaces, such as stoker incinerators, fluidized bed incinerators, and ash melting furnaces, are equipped with a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned matter after primary combustion. Primary combustion air is blown into the primary combustion chamber. Secondary combustion air is blown into the secondary combustion chamber.

[0003] The combustion exhaust gas after the primary combustion contains nitrogen oxides generated by the combustion. In order to reduce the concentration of nitrogen oxides, Patent Document 1 discloses a method for measuring the oxygen concentration in each of a plurality of divided regions of a secondary combustion chamber using intersecting lasers, and controlling the amount of air for secondary combustion in each of the plurality of divided regions based on the measurement.

[0004] Moreover, Patent Document 2 discloses a method of measuring the concentration distribution of nitrogen oxides in a secondary combustion chamber using a laser and controlling the amount of denitration agent injected based on the result.

[0005] As described in Patent Documents 1 and 2, the concentration of nitrogen oxides can be reduced by measuring the oxygen concentration distribution and the nitrogen oxide concentration distribution in the secondary combustion chamber and controlling the amount of secondary combustion air and the amount of denitrification agent injected based on the results.

[0006] However, even when these methods are used, the remaining nitrogen oxides must be denitrified using a catalytic denitration device, which requires a denitration agent and / or reheating of the combustion gas to promote the denitration reaction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-105594 A [Patent Document 2] JP 2012-2463 A Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, the combustion exhaust gas after primary combustion contains reducing gas capable of reducing the nitrogen oxides in addition to the nitrogen oxides produced by the combustion. If it were possible to cause the nitrogen oxides to react with this reducing gas, the concentration of the nitrogen oxides could be reduced without injecting additional denitrification agents. However, since the nitrogen oxides are generated in large amounts in areas with high oxygen concentrations, whereas the reducing gases are generated in large amounts in areas with low oxygen concentrations, the distribution of the two is different. For this reason, there is an issue that it is difficult to cause the nitrogen oxides to react with the reducing gas in the furnace.

[0009] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a furnace control method and apparatus capable of reacting nitrogen oxides with a reducing gas in the furnace, i.e., capable of denitration in the furnace. [Means for solving the problem]

[0010] In order to solve the above problems, one aspect of the present invention is a method for controlling a furnace equipped with a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned fuel after primary combustion, the method comprising: measuring a concentration distribution of nitrogen oxides and / or a concentration distribution of a nitrogen oxide-correlated gas whose concentration is correlated with that of nitrogen oxides in the secondary combustion chamber or downstream of the secondary combustion chamber; measuring a concentration distribution of a reducing gas that reduces nitrogen oxides and / or a concentration distribution of a reducing gas-correlated gas whose concentration is correlated with that of the reducing gas; and controlling at least one of the amount of air for secondary combustion, the amount of stirring gas for stirring the gas in the secondary combustion chamber, the amount of air for primary combustion, the fuel supply device feed speed, and the grate feed speed based on these concentration distributions.

[0011] Another aspect of the present invention is a furnace control device having a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned fuel after primary combustion, the furnace control device comprising: a distribution measuring device that measures the concentration distribution of nitrogen oxides and / or the concentration distribution of a nitrogen oxide-correlated gas whose concentration is correlated with that of nitrogen oxides in the secondary combustion chamber or downstream of the secondary combustion chamber, and measures the concentration distribution of a reducing gas that reduces nitrogen oxides and / or the concentration distribution of a reducing gas-correlated gas whose concentration is correlated with that of the reducing gas; and a combustion control device that controls at least one of the amount of air for secondary combustion, the amount of stirring gas for stirring the gas in the secondary combustion chamber, the amount of air for primary combustion, the fuel supply device feed speed, and the grate feed speed based on these concentration distributions. Effect of the Invention

[0012] According to the present invention, since nitrogen oxides and a reducing gas can be mixed in the furnace, the nitrogen oxides and the reducing gas can be reacted in the furnace, that is, in-furnace denitration becomes possible. [Brief description of the drawings]

[0013] [Figure 1] 1 is a vertical cross-sectional view of an incinerator equipped with a furnace control device according to one embodiment of the present invention. [Diagram 2] FIG. 11 is a vertical cross-sectional view of another example of an incinerator. [Diagram 3] FIG. 2 is a block diagram showing the configuration of a furnace control device according to the present embodiment. [Figure 4] 1 is a block diagram showing a configuration of a distribution measurement device of the present embodiment. [Diagram 5] 1 is a schematic diagram showing a light path p and a grid q. [Figure 6] FIG. 2 is a diagram showing a two-dimensional image of the NOx concentration distribution in a measurement area displayed on the display of the distribution measurement device. [Figure 7] FIG. 1 is a diagram conceptually explaining the degree of mixing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a detailed description will be given of a method and apparatus for controlling a furnace according to an embodiment of the present invention with reference to the accompanying drawings. However, the method and apparatus for controlling a furnace according to the present invention can be embodied in various forms and is not limited to the embodiments described in the present specification. The present embodiment is provided with the intention of enabling a person skilled in the art to fully understand the invention by fully disclosing the specification. (Incinerator)

[0015] Fig. 1 shows a vertical cross-sectional view of an incinerator 1 to which a furnace control device according to one embodiment of the present invention is applied. The incinerator 1 is a stoker-type incinerator having a fire grate, and burns waste as fuel. The incinerator 1 includes a hopper 3 into which waste is fed, a furnace body 4 in which the waste is combusted, and a boiler 5 disposed downstream of the furnace outlet 13.

[0016] The waste fed into the hopper 3 is sent to the grate 7, which also serves as an operating end, by a pusher of the fuel supply device 6, which also serves as an operating end. The grate 7 reciprocates, stirring and moving the waste by this reciprocating motion. The waste on the grate 7 is dried by blowing in primary combustion air from a blower 8, and then primary combustion is carried out, producing combustion exhaust gas and ash. The grate 7 comprises a drying grate 7a that dries and ignites the waste, a combustion grate 7b that burns the waste, and a post-combustion grate 7c that burns the unburned waste. The ash after the combustion falls from an ash drop port 9 and is discharged outside the furnace.

[0017] The total amount of primary combustion air supplied to the primary combustion chamber 11 from below the grate 7 is adjusted by a primary combustion air damper 10a, which is an operating terminal provided immediately adjacent to the blower 8. The amount of primary combustion air distributed to each wind box is adjusted by under-grate combustion air dampers 10b, 10c, and 10d, which are operating terminals provided on each pipe that supplies combustion air to each wind box. A number of wind boxes and a number of under-grate combustion air dampers are also provided in the furnace width direction, i.e., in the direction perpendicular to the paper surface of FIG. 1.

[0018] The combustible gas generated above the drying grate 7a and the combustion grate 7b and the combustion exhaust gas generated above the post-combustion grate 7c join and mix in the secondary combustion chamber 12 at the furnace outlet 13. Secondary combustion air is supplied to the secondary combustion chamber 12 by a blower 14, and secondary combustion of unburned fuel after the primary combustion is performed.

[0019] The total amount of secondary combustion air supplied to the secondary combustion chamber 12 is adjusted by a secondary combustion air damper 16a as an operating terminal provided immediately adjacent to the blower 14. A plurality of blowing nozzles 15 are provided in the secondary combustion chamber 12. The distribution amount of secondary combustion air supplied to each blowing nozzle 15 is adjusted by secondary combustion air dampers 16b and 16c as operating terminals provided in the piping that supplies secondary combustion air to the blowing nozzles 15.

[0020] A stirring gas is supplied to the secondary combustion chamber 12 of the furnace body 4 by a blower 17. The gas in the secondary combustion chamber 12 is stirred by the stirring gas. The supply amount of the stirring gas is adjusted by a stirring gas damper 19 as an operating end provided on a pipe that supplies the stirring gas to the blowing nozzle 18. The location of the blowing nozzle 18 is not particularly limited, and it may be upstream or downstream of the blowing nozzle 15. The type of the stirring gas is also not particularly limited, and may be air or a circulating gas obtained by circulating the combustion exhaust gas discharged from the furnace body 4.

[0021] Reference numeral 40 denotes a measurement area of ​​the distribution measuring device 22 that measures the concentration distribution of nitrogen oxides (hereinafter referred to as NOx) and the concentration distribution of reducing gas. The measurement area 40 is disposed in the secondary combustion chamber 12 or downstream of the secondary combustion chamber 12. The measurement area 40 is disposed downstream of the blowing nozzles 15, 18. The distribution measuring device 22 measures the concentration distribution of NOx and the concentration distribution of reducing gas downstream of the blowing nozzles 15, 18. The combustion control device 21 controls the distribution amount of secondary combustion air, the amount of stirring gas, etc. so that the measured concentration distribution of NOx and the concentration distribution of reducing gas are mixed into a concentration distribution. The distribution measuring device 22 and the combustion control device 21 will be described later.

[0022] A boiler 5 is installed downstream of the measurement area 40. Thermal energy of the combustion exhaust gas is recovered by the boiler 5 and the combustion exhaust gas is discharged to the outside through a chimney (not shown).

[0023] Thermometers for measuring the gas temperature in the furnace body 4 are provided at multiple positions within the furnace body 4. For example, a primary combustion chamber gas thermometer for measuring the temperature of the primary combustion chamber 11 is provided in the primary combustion chamber 11, a main flue gas thermometer is provided at a position below the furnace outlet 13, a furnace outlet lower thermometer is provided at a lower position of the furnace outlet 13, a furnace outlet middle gas thermometer is provided at a central position of the furnace outlet 13, and a furnace outlet gas thermometer is provided at a downstream position of the furnace outlet 13.

[0024] A boiler outlet oxygen concentration meter that measures the concentration of oxygen in the combustion exhaust gas is provided on the outlet side of the boiler 5. A gas concentration meter 31 that measures the concentrations of nitrogen oxides and carbon monoxide in the combustion exhaust gas is provided in the exhaust gas duct 30 connected to the chimney. In addition, a gas flow meter that measures the flow rate of the combustion exhaust gas is provided in the exhaust gas duct 30.

[0025] The measurement values ​​of the gas temperature, concentration, and flow rate measured by the various thermometers, gas concentration meter 31, boiler outlet oxygen concentration meter, and gas flow meter are transmitted to the combustion control device 21 as combustion process data and stored in the memory unit of the combustion control device 21. (Another example of an incinerator)

[0026] FIG. 2 shows another example of the incinerator 1. In this example, the measurement area 40 of the distribution measurement device 22 is arranged in the secondary combustion chamber 12. As in this example, the measurement area 40 may be arranged upstream of the blowing nozzle 15. Also, although not shown, the measurement area 40 may be arranged upstream of the blowing nozzle 18. When the measurement area 40 is arranged upstream of the blowing nozzles 15, 18, the distribution measurement device 22 measures the NOx concentration distribution and the reducing gas concentration distribution upstream of the blowing nozzles 15, 18. The combustion control device 21 predicts the required distribution amount of secondary combustion air, the amount of stirring gas, etc. based on the measured NOx concentration distribution and reducing gas concentration distribution. (Control device)

[0027] The control device 2 includes a distribution measuring device 22 that measures the NOx concentration distribution and the reducing gas concentration distribution in the secondary combustion chamber 12, and a combustion control device 21 that controls the operation amount of each operation terminal. Instead of measuring the NOx concentration distribution, the distribution measuring device 22 may measure the concentration distribution of oxygen (NOx-correlated gas) whose concentration is correlated with NOx.

[0028] The reducing gas is a gas that mainly reduces NO of NOx, and is at least one of ammonia, hydrogen, and hydrocarbon. Instead of measuring the concentration distribution of the reducing gas, the concentration distribution of carbon monoxide (reducing gas-correlated gas) whose concentration is correlated with that of the reducing gas may be measured. The concentration of carbon monoxide is correlated with the concentration of the entire reducing gas. By measuring the concentration distribution of carbon monoxide, the concentration distribution of the entire reducing gas can be estimated. (Combustion control device)

[0029] Next, the combustion control device 21 will be described. In this embodiment, the manipulated variables of each operating end (secondary combustion air volume, mixing gas volume, primary combustion air volume, fuel supply device feed rate, and grate feed rate) are controlled by the combustion control device 21. The combustion control device 21 controls the manipulated variables of each operating end based on a predetermined manipulated variable reference setting relational expression. The manipulated variable reference setting relational expression is a predetermined relational expression between the waste incineration amount set value (incineration amount target value) and the manipulated variable reference value of the operating end (manipulated variable target value). The manipulated variable reference setting relational expression is separately determined corresponding to each operating end, and is used to derive the manipulated variable reference value of the corresponding operating end based on the incineration amount set value.

[0030] As shown in FIG. 3, the combustion control device 21 includes a combustion process data acquisition unit 35, an operation quantity reference value calculation unit 32, an operation quantity control unit 33 such as a secondary combustion air amount control unit 33a described later, and an evaluation unit 34.

[0031] The operation amount reference value calculation unit 32 of the combustion control device 21 prestores the operation amount reference setting relational expression, and calculates the operation amount reference value of each operation terminal based on the incineration amount setting value. The combustion process data acquisition unit 35 acquires combustion process measurement values ​​(e.g., measurements by each thermometer, each concentration meter, and exhaust gas flow meter) as combustion state quantities in the furnace body 4 from the incinerator 1 in operation as combustion process data. The operation amount reference value calculation unit 32 adjusts (corrects) the operation amount reference value based on a control algorithm prestored in advance, such as fuzzy inference, according to the fluctuation of the combustion process data acquired by the combustion process data acquisition unit 35. Furthermore, the operation amount reference value calculation unit 32 adjusts (corrects) the operation amount reference value based on a control algorithm prestored in advance, such as fuzzy inference, based on the evaluation result of the evaluation unit 34. The evaluation unit 34 will be described later.

[0032] The control element control unit 33 outputs the operation amounts to the control elements so that the operation amounts (secondary combustion air amount, mixing gas amount, primary combustion air amount, fuel supply device feed rate, and grate feed rate) follow the operation amount reference value (operation amount reference value calculated or adjusted by the operation amount reference value calculation unit 32) based on a control algorithm stored in advance, such as PID control. That is, the secondary combustion air amount control unit 33a outputs the operation amounts to the secondary combustion air dampers 16a, 16b, and 16c (see FIG. 1) so that the secondary combustion air amount (total amount and distribution amount) follows the operation amount reference value. The mixing gas control unit 33b outputs the operation amount to the mixing gas damper 19 (see FIG. 1) so that the mixing gas amount follows the operation amount reference value. The primary combustion air amount control unit 33c outputs the operation amount to the primary combustion air damper 10a and the under-grate combustion air dampers 10b, 10c, and 10d (see FIG. 1) so that the primary combustion air amount (total amount and distribution amount) follows the operation amount reference value. The fuel supply device feed speed control unit 33d outputs the operation amount to the fuel supply device 6 (see FIG. 1) so that the fuel supply device feed speed follows the operation amount reference value. The grate speed control unit 33e outputs the operation amount to the grate 7 (see FIG. 1) so that the grate feed speed follows the operation amount reference value.

[0033] The combustion control device 21 includes a processor such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor), and a main storage unit such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The combustion control device 21 also includes a storage unit such as a volatile memory such as a RAM, a non-volatile memory such as a ROM, an EPROM (Erasable Programmable ROM), a hard disk drive, and a solid state drive. The above functions of the combustion control device 21 are realized by the processor executing various programs stored in the storage unit. The same applies to the analysis device 43 of the distribution measurement device 22 described later. (Distribution Measuring Device)

[0034] The distribution measurement device 22 measures the concentration distribution of NOx and the concentration distribution of reducing gas by using absorption spectroscopy using laser light and CT (Computed Tomography). Fig. 4 shows a measurement area 40 on a horizontal cross section. As shown in Fig. 4, the distribution measurement device 22 includes an irradiation device 41, a light receiving device 42, and an analysis device 43.

[0035] The irradiation device 41 irradiates the inside of the measurement region 40 with laser light. The light receiving device 42 receives the laser light that has passed through the measurement region 40. The analysis device 43 obtains the concentration distribution of NOx and the concentration distribution of reducing gas based on the electrical signal output by the light receiving device 42.

[0036] The irradiation device 41 includes a laser transmitter 44, a splitter 45, and a laser irradiator 46. The laser transmitter 44 is controlled by a laser control device (not shown) and outputs a laser beam in a wavelength region of the absorption band of NOx and a laser beam in a wavelength region of the absorption band of reducing gas. The splitter 45 splits the laser beam from the laser transmitter 44 into a plurality of optical paths and outputs the split beams. The splitter 45 and the laser irradiator 46 are connected by an optical fiber. The laser irradiator 46 is a collimator (lens) or the like for adjusting the traveling direction of the laser beam, and irradiates the measurement area 40 with the laser beam.

[0037] The light receiving device 42 includes a receiver 47 disposed opposite the laser irradiator 46. The receiver 47 includes a light receiving element such as a photodiode or a phototransistor, receives the laser light transmitted through the measurement area 40, and outputs an electrical signal according to the intensity of the received laser light. The receiver 47 and the analysis device 43 are connected by wiring that transmits the electrical signal.

[0038] The analyzer 43 amplifies the electrical signal from the receiver 47 with an amplifier, and analyzes the waveform (absorption spectrum) of the amplified signal using absorption spectroscopy and CT to obtain the concentration distribution of NOx and the concentration distribution of reducing gases.

[0039] Absorption spectroscopy and CT are explained below. Absorption spectroscopy is a measurement method that utilizes the property that when a laser beam of a certain wavelength is irradiated onto the gas to be measured, certain gas molecules contained in the gas to be measured absorb the laser beam of a specific wavelength, and the property that the amount of absorption depends on the concentration and temperature. The intensity of the incident light (I λ0 ) and transmitted light intensity (I λ ) ratio (I λ / I λ0 ) can be used to measure the concentration and temperature of the target gas. λ / I λ0 is expressed by the following relational equation (1) according to the Lambert-Beer formula.

[0040]

number

[0041] When a laser beam is irradiated onto the gas to be measured, the absorbance A at each optical path p is λ is expressed by the following relational expression (2).

[0042]

number

[0043] Here, A λ,p is the absorbance at the light path p, n q is the molecular number density at grid q, L p,q is the optical path length in the p direction through grid q, and α λ,q is the absorption coefficient at grid q. The optical path p and grid q are set as shown in Figure 5.

[0044] According to equation (2), the absorbance A for a certain wavelength is λ,p is the concentration n of the gas to be measured and the absorption coefficient α λ,q and the optical path length L. Since the optical path length L is known, the concentration n of the measurement target gas and the absorption coefficient α λ,q If we know the absorbance A for each light path p, λ,p Here, the absorption coefficient α λ,q is a function of temperature. Therefore, if the concentration n and temperature T of the target gas in each of the grids q included in each optical path p are known, the absorbance A λ,p is required.

[0045] Assuming the initial concentration and temperature, the actual value ((A λ,q ) data , absorbance data) and theoretical values ​​((A λ,q ) theory The concentration and temperature at each grid are converged so that the error in is minimized. This makes it possible to obtain the concentration n and temperature T of the target gas at each grid q, and therefore the concentration distribution and temperature distribution of the target gas.

[0046]

number

[0047] 6 shows a two-dimensional image of the NOx concentration distribution in the measurement area 40 displayed on the display of the distribution measurement device 22. The data of the NOx concentration distribution is transmitted to the evaluation unit 34 (see FIG. 3) of the combustion control device 21 via a communication line. Similarly, the data of the reducing gas concentration distribution is transmitted to the evaluation unit 34 (see FIG. 3) of the combustion control device 21 via a communication line.

[0048] The evaluation unit 34 of the combustion control device 21 determines the mixing degree of NOx based on the NOx concentration distribution data input from the distribution measurement device 22. Similarly, the evaluation unit 34 determines the mixing degree of the reducing gas based on the concentration distribution data of the reducing gas. For example, the Morishita Iδ index, Moran's I statistic which is a quantitative index related to spatial autocorrelation, fractal dimension, etc. can be used as an index representing the mixing degree.

[0049] The Morishita Iδ index is expressed by the following equation 4.

number

[0050] Moran's I statistic is expressed as follows:

number

[0051] The Morishita Iδ index and Moran's I statistic are conceptually explained below. Figures 7(a) to 7(c) show the gas concentration in each section when the measurement area 40 is divided into 4 x 4 sections. In the case of Figure 7(a), the NOx gas concentration in all sections of the measurement area 40 is 15%, so it is uniformly mixed. In the case of Figure 7(b), the gas concentration in the upper half of the sections is 20%, and the gas concentration in the lower half of the sections is 5%, so it is not mixed. In the case of Figure 7(c), the magnitude of variation in gas concentration (20%, 5%) is the same as in the case of Figure 7(b). However, since the section with a concentration of 20% and the section with a concentration of 5% are close to each other and are assumed to mix in a short time, the case of Figure 7(c) is inferior to the case of Figure 7(a), but is more spatially mixed than the case of Figure 7(b). The Morishita Iδ index and Moran's I statistic are indexes that take into account such positional information. A large index value indicates no mixing, and a small index value indicates mixing.

[0052] In addition, the overlapping area of ​​the high NOx concentration region and the high reducing gas concentration region may be used as an index representing the degree of mixing. The high NOx concentration region is, for example, a region where the NOx concentration is equal to or higher than a predetermined threshold. The high reducing gas concentration region is, for example, a region where the reducing gas concentration is equal to or higher than a predetermined threshold.

[0053] Next, the evaluation unit 34 evaluates the obtained degree of mixing of NOx and reducing gas, and sends the evaluation result to the operation amount reference value calculation unit 32. As the evaluation result, the evaluation unit 34 may send information on the degree of mixing of NOx and reducing gas directly to the operation amount reference value calculation unit 32, may send information in which the degree of mixing is weighted, or may send information on the necessity of adjusting the operation amount reference value determined based on the information on the degree of mixing.

[0054] Based on the evaluation result of the evaluation unit 34, the operation quantity reference value calculation unit 32 adjusts (corrects) at least one of the operation quantity reference values, i.e., at least one of the secondary combustion air amount, the stirring gas amount, the primary combustion air amount, the fuel supply device feed rate, and the grate feed rate, so that NOx and reducing gas are mixed.

[0055] The operation amount reference value calculation unit 32 preferably adjusts the distribution amount of the secondary combustion air as the secondary combustion air amount, and preferably adjusts the amount of the stirring gas when the stirring blowing nozzle 18 is present. This is because by adjusting these, NOx and reducing gas can be mixed efficiently.

[0056] For example, as shown in FIG. 7(b), when there are regions with high and low NOx concentrations in the measurement region 40, the operation quantity reference value calculation unit 32 reduces the amount of secondary combustion air distributed to the region with high NOx concentration and increases the amount of secondary combustion air distributed to the region with low NOx concentration. The operation quantity reference value calculation unit 32 also increases the amount of stirring gas. In this way, the NOx concentration can be made uniform. The same applies to the reducing gas. Note that the operation quantity reference value calculation unit 32 may adjust the amount of primary combustion air distributed, or adjust the fuel supply device feed rate or the grate feed rate in order to make the concentrations of NOx and reducing gas uniform.

[0057] While NOx is generated in a large amount in an area where the oxygen concentration is high, reducing gas is generated in a large amount in an area where the oxygen concentration is low, so the distribution of the two is different. According to the control device 2 of the incinerator 1 of this embodiment, NOx and reducing gas can be mixed in the incinerator 1, so that NOx and reducing gas can react in the incinerator 1.

[0058] It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without departing from the spirit and scope of the present invention.

[0059] For example, in the above embodiment, an example was described in which the incinerator was a stoker type incinerator, but the incinerator may also be a fluidized bed incinerator, an ash melting furnace, or the like.

[0060] In the above embodiment, the evaluation unit of the combustion control device evaluates the degree of mixing of NOx and reducing gas, and the operation amount reference value calculation unit adjusts the operation amount reference value of the operating end based on the evaluation result of the evaluation unit, but an operator may evaluate the degree of mixing of NOx and reducing gas, and adjust the operation amount reference value of the operating end based on the operator's evaluation result. [Explanation of symbols]

[0061] 1. Incinerator 2...Control device 11...Primary combustion chamber 12...Secondary combustion chamber 21...Combustion control device 22...Distribution measurement device

Claims

1. A method for controlling a furnace having a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned fuel after the primary combustion, comprising: In the secondary combustion chamber or downstream of the secondary combustion chamber, a concentration distribution of nitrogen oxides and / or a concentration distribution of a nitrogen oxide-correlated gas having a concentration correlated with that of nitrogen oxides is measured, and a concentration distribution of a reducing gas that reduces the nitrogen oxides and / or a concentration distribution of a reducing gas-correlated gas having a concentration correlated with that of the reducing gas is measured; A furnace control method for controlling at least one of the amount of secondary combustion air, the amount of stirring gas for stirring the gas in the secondary combustion chamber, the amount of primary combustion air, the fuel supply device feed rate, and the grate feed rate based on these concentration distributions.

2. The degree of mixing of gases is evaluated by measuring the concentration distribution.

2. The method of claim 1, further comprising controlling said at least one of said plurality of furnaces based on a result of said evaluation.

3. 3. A method as claimed in claim 1 or 2, characterized in that the nitrogen oxide associated gas is oxygen.

4. 3. The method of claim 1, wherein the reducing gas is at least one of ammonia, hydrogen, and a hydrocarbon.

5. 3. A method according to claim 1 or 2, characterized in that the reducing gas-correlated gas is carbon monoxide.

6. 3. A method for controlling a furnace according to claim 1, wherein the amount of secondary combustion air is controlled by controlling a distribution amount of secondary combustion air.

7. 3. The method for controlling a furnace according to claim 1, further comprising controlling the amount of the stirring gas.

8. A control device for a furnace having a primary combustion chamber for primary combustion and a secondary combustion chamber for secondary combustion of unburned fuel after the primary combustion, a distribution measuring device for measuring a concentration distribution of nitrogen oxides and / or a concentration distribution of a nitrogen oxide-correlated gas having a concentration correlated with that of nitrogen oxides in the secondary combustion chamber or downstream of the secondary combustion chamber, and for measuring a concentration distribution of a reducing gas that reduces the nitrogen oxides and / or a concentration distribution of a reducing gas-correlated gas having a concentration correlated with that of the reducing gas; A furnace control device comprising: a combustion control device that controls at least one of the amount of secondary combustion air, the amount of stirring gas for stirring the gas in the secondary combustion chamber, the amount of primary combustion air, the fuel supply device feed speed, and the grate feed speed based on these concentration distributions.

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