Combustion control method of combustion equipment

Abstract

When the ratio of fuel gas (G) to combustion air (Air) supplied to a burner (20) is adjusted by an air ratio control system (50) and the combustion air and the fuel gas are ejected from the burner into a furnace (10) for combustion, the atmosphere gas in the furnace (10) is guided to an oxygen concentration sensor (51) through a collection pipe (12). The oxygen concentration detected by the oxygen concentration sensor is output to an output control device (52), the moving average value of the oxygen concentration is obtained by the output control device, and the air ratio control system is controlled by the output control device on the basis of the moving average value of the oxygen concentration so as to adjust the ratio of combustion air and fuel supplied to the combustor.

Description

Technical Field

[0001] The present invention relates to a combustion control method for a combustion device, wherein the combustion device adjusts the ratio of fuel supplied to a burner through a fuel supply pipe and combustion air supplied to the burner through an air supply pipe by an air ratio control system, so that the combustion air and the fuel are ejected from the burner into a furnace for combustion. In particular, the method has the following characteristics: when the atmosphere gas in the furnace is sucked into a collection pipe and guided to an oxygen concentration sensor, the oxygen concentration in the furnace is detected by the oxygen concentration sensor, and the ratio of fuel supplied to the burner and combustion air is adjusted, stable combustion can be performed in a manner that the oxygen concentration in the furnace becomes a specified value. Background Art

[0002] Conventionally, in combustion equipment, the ratio of fuel supplied to the burner through a fuel supply pipe and combustion air supplied to the burner through an air supply pipe is adjusted so that the air ratio in the burner becomes a specified value, and the fuel and combustion air are ejected from the burner into the furnace and burned.

[0003] Here, when fuel and combustion air are ejected from the burner into the furnace and burned in such a manner that the air ratio in the burner becomes a specified value, patent document 1 shows the following: for a specified formula (A) showing the relationship between a flow coefficient N of a burner preset to a fixed value, a fuel flow rate preset relative to the combustion amount of the burner, a flow rate of combustion air calculated based on the fuel flow rate and the preset air ratio, and a supply pressure P0 of a fluid on the primary side of a flow regulating valve provided in the fuel supply system and the combustion air supply system, the measured value of the supply pressure P0 is applied to calculate the flow coefficient V of the flow regulating valve provided in the fuel supply system and the combustion air supply system, respectively, and the relationship between the valve opening S' of the flow regulating valve and the flow coefficient V' is measured in advance, the measured flow coefficient V' is compared with the flow coefficient V calculated by the calculation, and the deviation is calculated, and the valve opening is adjusted in such a manner that the deviation becomes zero, thereby controlling the combustion amount while keeping the air ratio fixed.

[0004] In addition, Patent Document 2 shows the following: at least a measured value of the opening of a fuel control valve whose relationship between a flow coefficient and an opening is known, a measured value of the opening of a combustion air control valve whose relationship between a flow coefficient and an opening is known, a measured value of the supply temperature and a supply pressure of a fuel supplied to a burner whose flow coefficient is known, a measured value of the supply temperature and a supply pressure of the combustion air supplied to the burner, a measured value of the temperature in a furnace, and a measured value of the pressure in a furnace are input into a burner control device, the burner control device determines the combustion amount of the burner according to a deviation between the measured value of the temperature in the furnace and a set value, and calculates the openings of the fuel control valve and the combustion air control valve corresponding to the fuel flow rate and the combustion air flow rate for maintaining the combustion amount of the determined burner through a compound throttling operation in a manner that maintains a preset combustion air ratio, so that the measured values ​​of the openings of the fuel control valve and the combustion air control valve are aligned with the combustion air ratio calculated through the compound throttling operation. When the openings of the material control valve and the combustion air control valve are adjusted in a manner consistent with the calculated values ​​of the openings of the above-mentioned control valves to control the flow rates of fuel and combustion air, in the above-mentioned burner control device, the above-mentioned measured values ​​are always updated to the latest measured values ​​and stored for a specified time portion, and when any of the above-mentioned measured values ​​exceeds the allowable range of the set values ​​for the above-mentioned each measurement item, the updating of the measured values ​​is stopped after a specified time has passed from the time point when the allowable range is exceeded. At the time point when the updating of the measured values ​​is stopped, the cause of the exceeding of the above-mentioned allowable range is judged based on the above-mentioned measured values ​​measured before the exceeding of the above-mentioned allowable range and the above-mentioned measured values ​​measured after the exceeding of the above-mentioned allowable range and stored in the burner control device. When the measured value of the above-mentioned fuel supply pressure drops sharply and exceeds the above-mentioned allowable range but the above-mentioned furnace temperature and the above-mentioned furnace pressure are within the above-mentioned allowable range, it is judged that the failure of the pressure sensor measuring the above-mentioned fuel supply pressure is the cause.

[0005] In addition, Patent Document 3 shows the following: when the air ratio in the burner is properly controlled, the pre-mixed gas before combustion is sampled and burned, and its reduction rate A = [CO2 + H2O] / [CO + H2] is measured, and an air ratio measurement value converted from the reduction rate A is obtained, and the deviation between the air ratio measurement value and a predetermined air ratio setting value is fed back to the mixing valve of the premixing device, thereby controlling the mixing ratio of the fuel gas and air of the premixing burner.

[0006] In addition, Patent Document 4 shows the following: In a combustion device that mixes air supplied through an air supply pipe and fuel gas supplied through a fuel supply pipe in a desired ratio and burns through a burner, a pressure equalizing valve is provided in the fuel supply pipe, air is guided from the air supply pipe to the above-mentioned pressure equalizing valve through a pressure pipe, an oxygen concentration sensor is provided to detect the oxygen concentration in the combustion exhaust gas after combustion through the burner, an air ratio control device is provided to control the pressure of air guided from the air supply pipe through the pressure pipe to the pressure equalizing valve based on the oxygen concentration in the combustion exhaust gas detected by the oxygen concentration sensor, and a flow control valve for controlling the flow rate of air is provided at a midway position of the air supply pipe that supplies air to the burner, a first pressure pipe provided at a position upstream of the flow control valve, a second pressure pipe provided at a position downstream of the flow control valve, and a third pressure pipe that guides air to the pressure equalizing valve are connected to a three-way regulating valve, and the three-way regulating valve is adjusted by the air ratio control device to control the pressure of air guided to the pressure equalizing valve through the third pressure pipe.

[0007] However, in actual combustion equipment, there is intrusive air that penetrates into the furnace from the outside through gaps such as the gap between the furnace and the door, joints on the furnace wall, and cracks. The intrusive air mixes with the combustion air in the furnace to burn the fuel. Therefore, the air ratio calculated from the oxygen concentration in the furnace where combustion is actually taking place is different from the air ratio in the burner after adjustment by the burner.

[0008] Furthermore, the amount of intrusion air intruding into the furnace decreases as the pressure in the furnace becomes higher, and increases as the pressure in the furnace decreases.

[0009] Furthermore, during the operation of the combustion equipment, the combustion volume of the burner changes due to changes or adjustments in the temperature in the furnace, and some of the multiple burners are extinguished or reignited. However, at this time, the amount of combustion exhaust gas from the burner changes significantly and the pressure in the furnace changes significantly. Along with this, the amount of intruding air changes, causing the oxygen concentration in the furnace to change.

[0010] Thus, in conventional combustion equipment, even if the air ratio in the burner is properly adjusted as described above, the oxygen concentration in the furnace actually performing combustion will fluctuate and deviate from the proper range, resulting in the generation of soot in the furnace or an increase in CO and NOx in the combustion exhaust gas.

[0011] However, in the contents disclosed in Patent Documents 1 to 4, when fuel and combustion air are jetted from a burner into a furnace and burned in the furnace so that the fuel and combustion air have a predetermined air ratio, no countermeasures are provided for the above-mentioned problem.

[0012] In addition, the following problem also exists in previous combustion equipment: when the atmosphere gas in the furnace is sucked into the collection pipe and guided to the oxygen concentration sensor to detect the oxygen concentration in the furnace, as shown in Patent Document 5, it takes time for the atmosphere gas to pass through the collection pipe and be guided to the oxygen concentration sensor. The oxygen concentration detected by the oxygen concentration sensor is not actually the oxygen concentration in the furnace after adjustment. Therefore, based only on the oxygen concentration detected at that time point, even if the air ratio in the burner is adjusted, it is difficult to burn in such a way that the oxygen concentration in the furnace becomes the specified value. Prior art literature Patent Literature

[0013] Patent Document 1: Japanese Patent No. 3495995 Patent Document 2: Japanese Patent No. 4234309 Patent Document 3: Japanese Patent No. 2741617 Patent Document 4: Japanese Patent No. 7073025 Patent Document 5: Japanese Patent Application Laid-Open No. 49-77689 Summary of the invention Technical problem to be solved by the invention

[0014] The object of the present invention is to solve the above-mentioned problems in a combustion device, which adjusts the ratio of the fuel supplied to the burner through a fuel supply pipe and the combustion air supplied to the burner through an air supply pipe by means of an air ratio control system, so that the combustion air and fuel are ejected from the burner into a furnace and burned.

[0015] That is, the subject of the present invention is that, in a combustion control method of a combustion device for controlling combustion in the above-mentioned combustion device, when the atmosphere gas in the furnace is sucked into a collection pipe and guided to an oxygen concentration sensor, the oxygen concentration in the furnace is detected by the oxygen concentration sensor and the ratio of fuel and combustion air supplied to the burner is adjusted, stable combustion can be performed in such a way that the oxygen concentration in the furnace becomes a specified value. Technical solutions adopted to solve technical problems

[0016] In the combustion control method of the combustion equipment of the present invention, in order to solve the above-mentioned problems, the ratio of the fuel supplied to the burner through the fuel supply pipe and the combustion air supplied to the burner through the air supply pipe is adjusted by an air ratio control system, and the combustion air and the fuel are ejected from the burner into the furnace for combustion. In the combustion control method of the combustion equipment, the atmosphere gas in the furnace is guided to the oxygen concentration sensor through the collection pipe, the oxygen concentration of the guided atmosphere gas is detected by the oxygen concentration sensor and output to the output control device, the moving average value of the detected oxygen concentration is calculated by the output control device, and the air ratio control system is controlled by the output control device based on the moving average value of the oxygen concentration. When adjusting the ratio of the combustion air and the fuel supplied to the burner, the ratio of the combustion air and the fuel supplied to the burner is adjusted in levels according to each specified control time tx.

[0017] Furthermore, in the combustion control method of the combustion equipment of the present invention, the atmosphere gas in the furnace is guided to the oxygen concentration sensor through the collection pipe, the oxygen concentration of the atmosphere gas in the furnace is detected by the oxygen concentration sensor and output to the output control device, the moving average of the detected oxygen concentration is calculated by the output control device, and the air ratio control system is controlled by the output control device based on the moving average of the oxygen concentration to adjust the ratio of combustion air and fuel supplied to the burner. Therefore, even if the oxygen concentration in the furnace changes repeatedly in a short period of time due to changes in the combustion state in the burner, there is no need to repeatedly adjust the ratio of combustion air and fuel supplied to the burner in a short period of time through the air ratio control system accordingly, and oscillation can be suppressed.

[0018] Furthermore, in the combustion control method of the combustion equipment of the present invention, when the air ratio control system is controlled by the output control device based on the moving average value of the oxygen concentration, the air ratio control system is controlled by the output control device based on the moving average value of the oxygen concentration so as to adjust the ratio of the combustion air and the fuel supplied to the burner in stages for each predetermined control time tx. In this way, the change in the oxygen concentration in the furnace can be detected at an appropriate time, and the ratio of the combustion air and the fuel supplied to the burner can be controlled at an appropriate time by the air ratio control system, and the operation of changing the ratio of the combustion air and the fuel supplied to the burner can be easily performed by the air ratio control system at an appropriate time.

[0019] Furthermore, when the air ratio control system is controlled by the output control device based on the moving average value of the oxygen concentration as described above, and the ratio of the combustion air and the fuel supplied to the burner is adjusted at each predetermined control time tx, it is preferred that the control time tx is longer than the detection time ta from when the atmosphere gas in the furnace is guided to the oxygen concentration sensor through the collection pipe and the oxygen concentration is detected. In this way, the ratio of the combustion air and the fuel supplied to the burner can be changed by the air ratio control system based on the moving average value of the oxygen concentration obtained by the output control device when the atmosphere gas in the furnace collected by the collection pipe is guided to the oxygen concentration sensor and the oxygen concentration is detected, and the ratio of the combustion air and the fuel supplied to the burner can be adjusted by the air ratio control system while appropriately feeding back the oxygen concentration in the furnace. It is particularly preferred that the control time tx is made consistent with the detection time ta. Effects of the Invention

[0020] In the combustion control method of the combustion equipment of the present invention, the oxygen concentration of the atmosphere gas in the furnace guided by the collection pipe is detected by the oxygen concentration sensor as described above, the moving average value of the detected oxygen concentration is calculated by the output control device, and the air ratio control system is controlled based on the calculated moving average value of the oxygen concentration to adjust the ratio of the combustion air and fuel supplied to the burner in stages according to each specified control time tx. Therefore, even if the oxygen concentration in the furnace changes repeatedly in a short period of time due to changes in the combustion state in the burner, there is no need to adjust the ratio of the combustion air and fuel supplied to the burner repeatedly in a short period of time accordingly through the air ratio control system, and the ratio of the combustion air and fuel supplied to the burner can be simply adjusted to an appropriate ratio at an appropriate time through the air ratio control system.

[0021] As a result, in the combustion control method of the combustion equipment of the present invention, even if the oxygen concentration in the furnace changes repeatedly in a short period of time due to changes in the combustion state in the burner, the ratio of the combustion air and fuel supplied to the burner can be simply and appropriately adjusted by the air ratio control system, so that stable combustion can be performed in such a way that the oxygen concentration in the furnace becomes a specified value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic explanatory diagram showing the state of a combustion plant used in a combustion control method of a combustion plant according to an embodiment of the present invention. Figure 2It is a timing diagram showing the change of the actual oxygen concentration in the furnace, the change of the oxygen concentration detected by the oxygen concentration sensor, the change of the moving average value of the oxygen concentration calculated by the output control device, and the change of the air ratio in the burner controlled by the air ratio control system in the combustion control method of the combustion equipment of the embodiment. DETAILED DESCRIPTION

[0023] The combustion control method of a combustion plant according to an embodiment of the present invention is described in detail below based on the drawings. The combustion control method of a combustion plant according to the present invention is not limited to the contents shown in the following embodiment, and can be implemented with appropriate changes within the scope of the invention.

[0024] In the combustion control method of the combustion equipment of this embodiment, if Figure 1 As shown, a burner 20 is provided in the furnace 10, and a fuel gas G such as coal gas as a fuel is supplied to the burner 20 through a fuel supply pipe 30, and combustion air Air is supplied to the burner 20 through an air supply pipe 40, so that the combustion air Air and the fuel gas G are ejected from the burner 20 into the furnace 10 and burned.

[0025] Furthermore, in the present embodiment, when the fuel gas G is supplied to the burner 20 through the fuel supply pipe 30 and the combustion air Air is supplied to the burner 20 through the air supply pipe 40 as described above, the flow control valve 31 provided on the fuel supply pipe 30 and the flow control valve 41 provided on the air supply pipe 40 are adjusted by the air ratio control system 50 to control the ratio of the fuel gas G and the combustion air Air supplied to the burner 20, and the combustion amount in the burner 20 and the air ratio μ in the burner 20 are adjusted to a predetermined value, so that the fuel gas G and the combustion air Air are ejected from the burner 20 into the furnace 10 and burned. (In addition, illustrations of doors, flues, etc. are omitted.)

[0026] Furthermore, in the present embodiment, the atmospheric gas in the furnace 10 is guided from the suction port 11 to the oxygen concentration sensor 51 through the collection pipe 12 , and the oxygen concentration of the guided atmospheric gas is detected by the oxygen concentration sensor 51 .

[0027] Here, when the atmosphere gas in the furnace 10 is guided from the suction port 11 to the oxygen concentration sensor 51 through the collection pipe 12, the oxygen concentration sensor 51 is not heat-resistant. In order to prevent the oxygen concentration sensor 51 from malfunctioning due to the heat generated by the furnace 10 and the heat of the atmosphere gas in the furnace 10 guided through the collection pipe 12, as shown in FIG. Figure 1As shown, the length of the collection pipe 12 is lengthened and the oxygen concentration sensor 51 is installed at a position away from the furnace 10. Therefore, the elapsed time ta is required to detect the elapsed time from the atmospheric gas in the furnace 10 passing through the collection pipe 12 to the oxygen concentration sensor 51 to detect the oxygen concentration.

[0028] Furthermore, in this embodiment, as described above, the oxygen concentration of the guided atmosphere gas is detected by the oxygen concentration sensor 51, and the oxygen concentration thus detected is output from the oxygen concentration sensor 51 to the output control device 52, and the moving average value of the detected oxygen concentration is calculated by the output control device 52.

[0029] Here, when the moving average value of the oxygen concentration detected by the oxygen concentration sensor 51 is obtained by the output control device 52, the calculation time for calculating the moving average value is not particularly limited. However, if the calculation time is short, the changes based on the changes in the oxygen concentration in the furnace will increase. On the other hand, if the calculation time is too long, it will be difficult to fully detect the changes in the oxygen concentration in the furnace. For example, in the case where the burner 20 is a paired regenerative burner that alternately repeats combustion and heat storage, the cycle time of the cyclic action of combustion and heat storage can be used as the calculation time to calculate the moving average value. In the case of a normal burner 20, the calculation time is generally shorter than that of a regenerative burner. In addition, the calculation time can also be determined based on experiments or previous data.

[0030] In addition, based on the moving average value of the oxygen concentration calculated in the output control device 52, the air ratio control system 50 is controlled by the output control device 52, and the flow regulating valve 31 provided on the fuel supply pipe 30 and the flow regulating valve 41 provided on the air supply pipe 40 are adjusted by the air ratio control system 50 to control the ratio of the fuel gas G and the combustion air Air supplied to the burner 20, thereby adjusting the air ratio μ inside the burner 20.

[0031] Here, when the air ratio control system 50 is controlled based on the moving average value of the oxygen concentration calculated in the output control device 52, the air ratio control system 50 is controlled based on the moving average value of the oxygen concentration through the output control device 52, and the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 is adjusted according to each specified control time tx, and the air ratio μ in the burner 20 is controlled according to each specified control time tx.

[0032] In this way, the change in oxygen concentration in the furnace 10 can be detected at an appropriate time, and the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 can be controlled at an appropriate time through the air ratio control system 50. The air ratio μ in the burner 20 can be adjusted by simply changing the ratio of the combustion air Air and the fuel gas G supplied to the burner 20.

[0033] In addition, when the air ratio control system 50 is controlled based on the moving average value of the oxygen concentration through the output control device 52, and the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 is adjusted according to each specified control time tx, the control time tx is longer than the detection time ta from the time when the atmosphere gas in the furnace 10 is guided to the oxygen concentration sensor 51 through the collection pipe 12 and the oxygen concentration is detected, the air ratio control system 50 can adjust the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 while appropriately feeding back the oxygen concentration in the furnace 10.

[0034] In this way, control based on the result of the change in the oxygen concentration in the furnace 10 due to the change in the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 can be achieved, which is a form of original feedback control.

[0035] Here, the detection elapsed time ta can be obtained by actual measurement, calculation, or the like.

[0036] Next, based on Figure 2 To illustrate the combustion control method using the combustion equipment of the present embodiment, the atmosphere gas in the furnace 10 is guided to the oxygen concentration sensor 51 through the collection pipe 12 to detect the oxygen concentration, the moving average value of the detected oxygen concentration is calculated by the output control device 52, the air ratio control system 50 is controlled based on the calculated moving average value of the oxygen concentration, and the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 is adjusted to control the air ratio μ in the burner 20.

[0037] here, Figure 2 The timing diagram shows the change in actual oxygen concentration in the furnace 10, the change in oxygen concentration detected by the oxygen concentration sensor 51, the change in the moving average of the oxygen concentration obtained by the output control device 52, and the change in the air ratio in the burner controlled by the air ratio control system 50. The purpose is to control the moving average of the oxygen concentration so that it falls within a specified range.

[0038] And, if Figure 2As shown, the change in oxygen concentration detected by the oxygen concentration sensor 51 changes with respect to the change in oxygen concentration in the furnace 10, and changes with an offset by the detection elapsed time ta from when the atmospheric gas in the furnace 10 is guided to the oxygen concentration sensor 51 through the collection pipe 12 and the oxygen concentration is detected. In addition, in this example, the detection elapsed time ta is 10 seconds.

[0039] Next, based on the change in oxygen concentration detected by the oxygen concentration sensor 51, the change in the moving average value of the oxygen concentration is calculated by the output control device 52, and based on the calculated moving average value of the oxygen concentration in each specified control time tx, the air ratio control system 50 is controlled by the output control device 52. The air ratio control system 50 adjusts the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 at each control time tx.

[0040] By setting the moving average value in this way, the amplitude of the oxygen concentration detected by the oxygen concentration sensor 51 can be reduced, thereby facilitating control.

[0041] Here, in this example, the control time tx is set to 10 seconds like the detection time ta, and the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 is adjusted by the air ratio control system 50 while feeding back the detection time ta from when the atmosphere gas in each furnace 10 is guided to the oxygen concentration sensor 51 and the oxygen concentration is detected. In addition, if the control time tx is longer than the detection time ta, the control is based on the result after the oxygen concentration changes, so the control time tx can be longer than the detection time ta. (In the above example, it can be more than 10 seconds.)

[0042] Furthermore, when the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 is adjusted at each control time tx by the air ratio control system 50 based on the moving average value of the oxygen concentration at each control time tx as described above, the air ratio μ in the burner 20 changes in levels at each control time tx based on the change in the moving average value of the oxygen concentration at each control time tx. When the change in the moving average value of the oxygen concentration at the control time tx is small, the air ratio μ in the burner 20 remains fixed. On the other hand, when the change in the moving average value of the oxygen concentration at the control time tx is large, the air ratio μ in the burner 20 is changed in levels to match the change in the moving average value of the oxygen concentration, and the level of change of the air ratio μ in the burner 20 is adjusted to match the magnitude of the change in the moving average value of the oxygen concentration.

[0043] That is, an attempt is made to change the air ratio more significantly as the moving average value of the oxygen concentration deviates more from the predetermined range, so as to quickly restore it to the predetermined range.

[0044] As a specific example, in Figure 2 In the example shown, the moving average value of the oxygen concentration is set within a predetermined range of 1.8 to 2.2%, and the air ratio μ in the combustor 20 is maintained in the state shown in the figure.

[0045] Furthermore, when the moving average value of the oxygen concentration increases to 2.2-2.4%, the air ratio μ in the burner 20 is restored to the specified range by reducing it by one level (0.02). When the moving average value of the oxygen concentration increases to more than 2.4%, the air ratio μ in the burner 20 is quickly restored to the specified range by reducing it by two levels (0.04).

[0046] Furthermore, when the moving average value of the oxygen concentration decreases to 1.6 to 1.8%, the air ratio μ in the burner 20 is restored to the prescribed range by increasing by one level (0.02), and when the moving average value of the oxygen concentration decreases to less than 1.6%, the air ratio μ in the burner 20 is quickly restored to the prescribed range by increasing by two levels (0.04). The number of levels and the amount of change are appropriately determined.

[0047] In this way, even if the oxygen concentration in the furnace 10 changes repeatedly in a short period of time due to changes in the combustion state in the burner 20, or if the oxygen concentration in the furnace 10 changes significantly, there is no need to repeatedly adjust the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 through the air ratio control system 50 in a short period of time accordingly. Instead, the air ratio control system 50 adjusts the ratio of the combustion air Air and the fuel gas G supplied to the burner 20 at a level corresponding to the change in oxygen concentration at each control time tx, thereby simply and appropriately adjusting the air ratio μ in the burner 20 so that the oxygen concentration in the furnace 10 becomes an appropriate value. Explanation of symbols

[0048] 10 furnaces 11 Suction port 12 Collection Tubes 20 burners 30 fuel supply pipe 31 Flow Control Valve 40 Air supply pipe 41 Flow Control Valve 50 Air Ratio Control System 51 oxygen concentration sensor 52 Output control device Air Combustion air G Fuel Gas ta detection elapsed time tx control time μAir ratio.

Claims

1. A method for controlling a combustion device, The combustion equipment adjusts the ratio of the fuel supplied to the burner through the fuel supply pipe and the combustion air supplied to the burner through the air supply pipe by an air ratio control system, and makes the combustion air and fuel sprayed from the burner into the furnace for combustion, and is characterized in that: The atmosphere gas in the furnace is guided to the oxygen concentration sensor through the collection tube, the oxygen concentration of the guided atmosphere gas is detected by the oxygen concentration sensor and output to the output control device, the moving average value of the detected oxygen concentration is calculated by the output control device, and the air ratio control system is controlled by the output control device based on the moving average value of the oxygen concentration. When adjusting the ratio of combustion air and fuel supplied to the burner, the ratio of combustion air and fuel supplied to the burner is adjusted in levels according to each specified control time (tx).

2. The method for controlling a combustion device according to claim 1, characterized in that: When the air ratio control system is controlled based on a moving average value of oxygen concentration and the ratio of combustion air and fuel supplied to the burner is adjusted at each specified control time (tx), the control time (tx) is longer than the detection time (ta) from the time the atmospheric gas in the furnace is guided to the oxygen concentration sensor through the collection pipe and the oxygen concentration is detected.

3. The control method of the combustion equipment according to claim 1 or 2, characterized in that: The level of change in the ratio of combustion air and fuel supplied to the burner is adjusted in accordance with the magnitude of the change in the moving average value of the oxygen concentration detected by the output control device from a prescribed range, and when the change in the moving average value of the oxygen concentration changes significantly from the prescribed range, the level of change in the ratio of combustion air and fuel supplied to the burner is increased.

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