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 fuel gas and the combustion air are ejected from the burner into a furnace (10) for combustion, a change in oxygen concentration in the furnace caused by a change in air entering the furnace is detected by an oxygen concentration sensor (51). The oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output control device to the air ratio control system, and the ratio of combustion air and fuel supplied to the burner is adjusted by the air ratio control system.

Description

Technical Field

[0001] The present invention relates to a combustion device, which adjusts the ratio of fuel supplied through a fuel supply pipe and combustion air supplied through an air supply pipe by an air ratio control system and supplies the fuel to a burner, so that the combustion air and fuel are ejected from the burner into a furnace and burn. In particular, the device has the following characteristics: when the amount of air intruding into the furnace changes due to the change in the combustion amount in the burner, so that the oxygen concentration in the furnace has changed, and in a furnace in which a plurality of burners are provided with a cooling air guide pipe for guiding cooling air on the periphery of a fuel supply nozzle for supplying fuel and a combustion air supply nozzle for supplying combustion air on the periphery of the cooling air guide pipe, the number of burners that stop combustion changes, and the amount of cooling air guided into the furnace from the cooling air guide pipe of the stopped burner changes, so that the oxygen concentration in the furnace has changed, etc., the air ratio control system can quickly adjust the ratio of combustion air and fuel supplied to the burner, so that the air ratio in the furnace becomes a specified value and combustion is carried out stably. Background Art

[0002] Conventionally, in combustion equipment, fuel supplied through a fuel supply pipe and combustion air supplied through an air supply pipe are supplied to a burner at a predetermined ratio, and the fuel and combustion air are ejected from the burner into a furnace and burned.

[0003] Here, when fuel and combustion air are sprayed from a burner into a furnace and are burned in a manner such that the fuel and combustion air in the furnace become a specified air ratio, 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 a manner such 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 supply pressure of a fuel supplied to a burner whose flow coefficient is known, a measured value of the supply temperature and 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 based on 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 equal to the measured values ​​of the openings of the fuel control valve and the combustion air control valve obtained through the compound throttling operation. When the openings of the fuel control valve and the combustion air control valve are adjusted in a manner such that the calculated values ​​of the openings of the above-mentioned control valves are consistent with each other 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 when the allowable range is exceeded. At the time when the updating of the measured values ​​is stopped, the cause of exceeding the above-mentioned allowable range is judged based on the above-mentioned measured values ​​measured before exceeding the above-mentioned allowable range and the above-mentioned measured values ​​measured after exceeding the above-mentioned allowable range 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 a failure of the pressure sensor measuring the above-mentioned fuel supply pressure is the cause.

[0005] On the other hand, the air ratio during operation of the combustion equipment is adjusted so as to be set to an appropriate value capable of reducing CO, soot, and NOx in the combustion exhaust gas.

[0006] 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 actually burning in the furnace (the air ratio in the furnace) is different from the air ratio regulated by the burner (the air ratio in the burner).

[0007] 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.

[0008] 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. As a result, the amount of intruding air changes, and the air ratio in the furnace also changes.

[0009] Thus, in conventional combustion equipment, even if the air ratio of the burner (the air ratio in the fuel gas) is adjusted to an appropriate value as described above, the air ratio actually burned in the furnace (the air ratio in the furnace) is different and fluctuates, and there is a problem that measures to reduce CO, soot, and NOx in the combustion exhaust gas cannot be fully implemented.

[0010] However, in the contents disclosed in Patent Documents 1 and 2, when fuel and combustion air are ejected from a burner into a furnace and burned so that the fuel and combustion air in the furnace have a predetermined air ratio, no countermeasures are provided for the above-mentioned problem. Prior art literature Patent Literature

[0011] Patent Document 1: Japanese Patent No. 3495995 Patent Document 2: Japanese Patent No. 4234309 Summary of the invention Technical problem to be solved by the invention

[0012] The object of the present invention is to solve the above-mentioned problem in a combustion device which adjusts the ratio of fuel supplied through a fuel supply pipe and combustion air supplied through an air supply pipe by means of an air ratio control system and supplies the air to a burner, so that the combustion air and fuel are ejected from the burner into a furnace and burnt.

[0013] That is, the subject of the present invention is that, in the above-mentioned combustion equipment, when the amount of air invading into the furnace changes due to the change in the combustion amount in the burner, so that the oxygen concentration in the furnace has changed, and in a furnace in which a plurality of burners are provided with a cooling air guide pipe for guiding cooling air on the periphery of a fuel supply nozzle for supplying fuel, and a combustion air supply nozzle for supplying combustion air is provided on the periphery of the cooling air guide pipe, the number of burners that stop combustion changes, and the amount of cooling air guided into the furnace from the cooling air guide pipe of the stopped burner changes, so that the oxygen concentration in the furnace has changed, etc., the ratio of combustion air and fuel supplied to the burner can be quickly adjusted by the air ratio control system so that the air ratio in the furnace becomes a specified value and combustion is stable. Technical solutions adopted to solve technical problems

[0014] In the combustion equipment of the present invention, in order to solve the above-mentioned problems, an oxygen concentration sensor for detecting changes in the oxygen concentration in the furnace caused by changes in the amount of air intruding into the furnace is provided in the combustion equipment in which the ratio of the fuel supplied through the fuel supply pipe and the combustion air supplied through the air supply pipe is adjusted by an air ratio control system and supplied to the burner so that the combustion air and the fuel are ejected from the burner into the furnace for combustion. The oxygen concentration in the furnace detected by the oxygen concentration sensor is output from an output control device to the air ratio control system. Based on the oxygen concentration in the furnace detected by the oxygen concentration sensor, the ratio of the combustion air and the fuel supplied to the burner is adjusted by the air ratio control system so that the fuel and the combustion air are burned in the furnace. , when the amount of combustion exhaust gas in the furnace increases and the pressure in the furnace becomes higher due to the increase in the combustion amount in the burner, the amount of air intruding into the furnace decreases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner to increase the air ratio in the burner; on the other hand, when the amount of combustion exhaust gas in the furnace decreases and the pressure in the furnace decreases due to the decrease in the combustion amount of the burner, the amount of intrusion air intruding into the furnace increases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner to reduce the air ratio in the burner.

[0015] Furthermore, in the combustion equipment of the present invention, an oxygen concentration sensor is used to detect the change in the oxygen concentration in the furnace caused by the change in the amount of air invading the furnace. The oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output control device to the air ratio control system. The air ratio control system adjusts the ratio of the combustion air and fuel supplied to the burner so that the combustion air and fuel are burned in the furnace. Therefore, even if the amount of air invading the furnace changes, the combustion air and fuel in the furnace can be quickly made to have a specified air ratio, thereby performing stable combustion.

[0016] Furthermore, in the combustion equipment of the present invention, when the amount of air intruding into the furnace decreases and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner to increase the air ratio in the burner. On the other hand, when the amount of air intruding into the furnace increases and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner to decrease the air ratio in the burner.

[0017] Furthermore, in the combustion equipment of the first aspect of the present invention, when the amount of combustion exhaust gas in the furnace increases and the pressure in the furnace becomes higher due to the increase in the combustion amount in the burner as described above, the amount of air intruding into the furnace decreases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the ratio of the combustion air and fuel supplied to the burner is adjusted by the air ratio control system to increase the air ratio in the burner; on the other hand, when the amount of combustion exhaust gas in the furnace decreases and the pressure in the furnace decreases due to the decrease in the combustion amount of the burner, the amount of intrusion air intruding into the furnace increases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the ratio of the combustion air and fuel supplied to the burner is adjusted by the air ratio control system to reduce the air ratio in the burner. In this way, even if the combustion amount in the burner has changed, the air ratio in the furnace can quickly become a specified value, thereby performing stable combustion.

[0018] In addition, in the combustion equipment of the second aspect of the present invention, a plurality of burners are provided in the furnace, and each burner is provided with a cooling air guide pipe for guiding cooling air on the periphery of a fuel supply nozzle for supplying fuel, and a combustion air supply nozzle for supplying combustion air is provided on the periphery of the cooling air guide pipe. When the number of burners that have stopped combustion increases, the amount of cooling air intruding into the furnace from the cooling air guide pipe in the burners that have stopped combustion increases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burners that are currently burning, thereby reducing the air ratio in the burners that are currently burning. On the other hand, when the number of burners that have stopped combustion decreases, the amount of cooling air intruding into the furnace from the cooling air guide pipe in the burners that have stopped combustion decreases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burners that are currently burning, thereby increasing the air ratio in the burners that are currently burning. Thus, even if the number of burners that stop combustion changes and the amount of cooling air entering the furnace from the cooling air guide pipe changes, the air ratio in the furnace can be quickly made a predetermined value, thereby achieving stable combustion. Effects of the Invention

[0019] In the combustion equipment of the first aspect and the second aspect of the present invention, the change in the oxygen concentration in the furnace caused by the change in the amount of air intruding into the furnace is detected by an oxygen concentration sensor, and the oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output control device to the air ratio control system. Based on the oxygen concentration in the furnace detected by the oxygen concentration sensor, the ratio of the combustion air and fuel supplied to the burner is adjusted by the air ratio control system. Therefore, even if the amount of intruding air intruding into the furnace has changed, the ratio of the combustion air and fuel supplied to the burner can be appropriately adjusted by the air ratio control system based on the oxygen concentration in the furnace detected by the oxygen concentration sensor, so that the air ratio in the furnace can quickly reach the specified value, thereby performing stable combustion.

[0020] In addition, since the value of the oxygen concentration in the furnace and the value of the air ratio in the furnace are proportional to each other, the oxygen concentration in the furnace can be measured and the air ratio in the furnace can be converted from the value by calculation.

[0021] The combustion amount is adjusted by the flow rates of fuel and combustion air, and the air ratio is mainly adjusted by the flow rate of combustion air. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram showing the following structure: In the combustion equipment of embodiment 1 of the present invention, based on the oxygen concentration in the furnace detected by the oxygen concentration sensor, the ratio of the combustion air supplied to the burner and the fuel gas as fuel is adjusted by an air ratio control system so that the air ratio in the burner becomes a specified value. Figure 2 (A) is a schematic diagram showing the following state: in the combustion equipment of the first embodiment, when the combustion amount in the burner increases and the amount of air intruding into the furnace decreases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the ratio of the combustion air and the fuel gas supplied to the burner is adjusted to increase the air ratio in the burner; Figure 2 (B) is a schematic diagram showing the following state: in the combustion equipment of the above-mentioned embodiment 1, when the combustion amount in the burner decreases and the amount of air intruding into the furnace increases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the ratio of the combustion air and fuel gas supplied to the burner is adjusted to reduce the air ratio in the burner. Figure 3 (A) is a timing chart showing changes in the combustion amount, changes in the pressure in the furnace, changes in the amount of air intruding into the furnace, changes in the oxygen concentration in the furnace, and changes in the air ratio in the burner when the combustion amount in the burner is increased in the combustion equipment of the first embodiment; Figure 3(B) is a timing diagram showing changes in the combustion amount, changes in the pressure in the furnace, changes in the amount of air intruding into the furnace, changes in the oxygen concentration in the furnace, and changes in the air ratio in the burner when the combustion amount in the burner is reduced in the combustion equipment of the above-mentioned embodiment 1. Figure 4 This is a schematic diagram showing the following state: In the combustion equipment of embodiment 2 of the present invention, a cooling air guide pipe for guiding cooling air is provided on the periphery of a fuel gas supply nozzle for supplying fuel gas, and a combustion air supply nozzle for supplying combustion air is provided on the periphery of the cooling air guide pipe. A plurality of burners are provided in the furnace, and combustion is performed in all the burners. Figure 5 This is a schematic explanatory diagram showing a state in which combustion of a part of burners provided in a furnace is stopped in the combustion equipment of the second embodiment. Figure 6 is a timing chart showing the following contents: In the combustion equipment of the above-mentioned embodiment 2, from the combustion in all the burners Figure 4 The state shown is changed to stop the combustion of some burners. Figure 5 In the state shown, there are changes in the combustion amount, changes in the pressure in the furnace, changes in the amount of cooling air intruding into the furnace from the cooling air guide pipe, changes in the oxygen concentration in the furnace, and changes in the air ratio in the burner. Figure 7 is a timing chart showing the following contents: In the combustion equipment of the second embodiment, from the point at which the combustion of a part of the burners is stopped Figure 5 The status shown changes to combustion in all burners. Figure 4 In the state shown, there are changes in the combustion amount, changes in the pressure in the furnace, changes in the amount of cooling air intruding into the furnace from the cooling air guide pipe, changes in the oxygen concentration in the furnace, and changes in the air ratio in the burner. DETAILED DESCRIPTION

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

[0024] (Implementation Method 1) In the combustion device of the first embodiment, if Figure 1As shown, a burner 20 is provided in a furnace 10 having a door 12 for opening and closing an opening 11, and a fuel gas G such as coal gas is supplied to the burner 20 as a fuel 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 burnt.

[0025] Furthermore, in the combustion equipment of embodiment one, 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 regulating valve 31 arranged on the fuel supply pipe 30 and the flow regulating valve 41 arranged 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 μA in the burner 20 are adjusted to specified values, so that the fuel gas G and the combustion air Air are ejected from the burner 20 into the furnace 10 and burned.

[0026] In addition, in the combustion equipment of the first embodiment, an oxygen concentration sensor 51 for detecting the oxygen concentration in the furnace 10 is provided, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to the air ratio control system 50 through the output control device 52. Based on the output oxygen concentration in the furnace 10, it is converted into the air ratio in the furnace 10, and the flow control valve 31 provided in the fuel supply pipe 30 and the flow control valve 41 provided in 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 adjust the combustion amount in the burner 20 and the air ratio μA in the burner 20. In addition, the combustion amount in the burner 20 is adjusted by the flow rates of the fuel gas G and the combustion air Air, and the air ratio μA in the burner 20 is mainly adjusted by the flow rate of the combustion air Air.

[0027] Here, in the combustion device of the first embodiment, Figure 2 (A) and Figure 3 As shown in (A), when the amount of combustion air Air and fuel gas G supplied to the burner 20 is increased to increase the combustion amount in the burner 20, the amount of combustion exhaust gas in the furnace 10 increases, so that the pressure in the furnace 10 (furnace pressure) becomes higher, and the amount of intruding air Air' that intrudes into the furnace 10 from the outside through gaps such as gaps between the furnace 10 and the door 12, joints and cracks on the wall 13 of the furnace 10 (intrusive air amount) is reduced, thereby reducing the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51.

[0028] Furthermore, when the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 decreases as described above, the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to the air ratio control system 50 through the output control device 52, converted into the air ratio in the furnace 10, and the flow regulating valve 41 provided in the air supply pipe 40 is adjusted by the air ratio control system 50, so that the air ratio μB in the burner 20 increases compared with the original air ratio μA (μB>μA), and the oxygen concentration in the furnace 10 is restored to the original oxygen concentration, thereby restoring the air ratio in the furnace 10.

[0029] In this way, even when the combustion amount in the burner 20 is increased, the oxygen concentration in the furnace 10 can be restored to the original oxygen concentration, and the air ratio in the furnace 10 can be quickly stabilized, so that the fuel gas G can be stably combusted.

[0030] In addition, in the combustion device of the first embodiment, if Figure 2 (B) and Figure 3 As shown in (B), when the amount of combustion air Air and fuel gas G supplied to the burner 20 is reduced to reduce the combustion amount in the burner 20, the amount of combustion exhaust gas in the furnace 10 is reduced, so that the pressure in the furnace 10 (furnace pressure) becomes lower, and the amount of intruding air Air' that intrudes into the furnace 10 from the outside through gaps such as gaps between the furnace 10 and the door 12, joints and cracks on the wall 13 of the furnace 10 (intrusive air amount) increases, thereby increasing the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51.

[0031] Furthermore, when the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 increases as described above, the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to the air ratio control system 50 through the output control device 52, converted into the air ratio in the furnace 10, and the flow regulating valve 41 provided in the air supply pipe 40 is adjusted by the air ratio control system 50, so that the air ratio μC in the burner 20 is reduced from the original air ratio μA (μC<μA), and the oxygen concentration in the furnace 10 is restored to the original oxygen concentration, thereby restoring the air ratio in the furnace 10.

[0032] In this way, even when the combustion amount in the burner 20 is reduced, the oxygen concentration in the furnace 10 can be restored to the original oxygen concentration, the air ratio in the furnace 10 can be quickly stabilized, and the fuel gas G can be stably combusted.

[0033] (Implementation Method 2) In the combustion device of the second embodiment, if Figure 4 and Figure 5As shown, the furnace 10 is provided with a plurality of burners 20, in each burner 20, the fuel gas G is guided to the fuel gas supply nozzle 21 through the fuel supply pipe 30, and the cooling air Air" is guided to the cooling air guide pipe 22 arranged on the periphery of the fuel gas supply nozzle 21 through the valve 61 arranged on the cooling air supply pipe 60, and the combustion air Air is guided to the combustion air supply nozzle 23 arranged on the periphery of the cooling air guide pipe 22 through the air supply pipe 40.

[0034] Furthermore, in the burner 20, the fuel gas G guided to the fuel gas supply nozzle 21 through the fuel supply pipe 30, the cooling air Air" guided to the periphery of the fuel gas supply nozzle 21 through the cooling air guide pipe 22, and the combustion air Air guided to the combustion air supply nozzle 23 through the air supply pipe 40 are ejected into the furnace 10 and burned.

[0035] In addition, in the combustion equipment in embodiment 2, an air ratio control system 50 is respectively provided corresponding to each burner 20, and a flow regulating valve 31 is respectively provided on the fuel supply pipe 30 that guides the fuel gas G to each burner 20, and a flow regulating valve 41 is respectively provided on the air supply pipe 40 that guides the combustion air Air.

[0036] In addition, in the combustion equipment of the second embodiment, an oxygen concentration sensor 51 for detecting the oxygen concentration in the furnace 10 is provided, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to each of the air ratio control systems 50 through the output control device 52. Based on the output oxygen concentration in the furnace 10, the flow control valve 31 provided in the fuel supply pipe 30 and the flow control valve 41 provided in the air supply pipe 40 corresponding to each burner 20 are controlled by each air ratio control system 50 to adjust the ratio of the fuel gas G and the combustion air Air supplied to the burner 20, and adjust the combustion amount in each burner 20 and the air ratio μD in each burner 20. In addition, the combustion amount in each burner 20 is adjusted by the flow rate of the fuel gas G and the combustion air Air, and the air ratio μD in each burner 20 is mainly adjusted by the flow rate of the combustion air Air.

[0037] Here, in the combustion device of the second embodiment, Figure 4As shown in the figure, when combustion is carried out in all the burners 20, cooling air Air" is supplied to the cooling air guide pipe 22 arranged in each burner 20 through the cooling air supply pipe 60, and based on the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51, the flow regulating valve 31 arranged on the fuel supply pipe 30 and the flow regulating valve 41 arranged on the air supply pipe 40 corresponding to each burner 20 are controlled by each air ratio control system 50 to adjust the amount of combustion air Air and fuel gas G supplied to each burner 20, and adjust the combustion amount in each burner 20 and the air ratio μD in each burner 20 for combustion.

[0038] In addition, in the combustion device of the second embodiment, Figure 5 As shown in the figure, when the combustion in a part of the burners 20 is stopped, in the burner 20 where the combustion is stopped, 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 relative to the burner 20 are closed by the air ratio control system 50, so that the combustion is stopped in a manner that the fuel gas G and the combustion air Air are not introduced to the fuel gas supply nozzle 21 and the combustion air supply nozzle 23. On the other hand, in order to prevent the fuel gas supply nozzle 21 protruding into the interior of the burner 20 where the combustion is stopped from being deformed due to the heat in the furnace 10, in the burner 20 where the combustion is stopped, cooling air Air is also supplied to the furnace 10 through the cooling air supply pipe 60.

[0039] Here, from Figure 4 The state in which all burners 20 are performing combustion is shown as follows: Figure 5 When the combustion in a part of the burners 20 is stopped as shown in FIG. Figure 6 As shown, the combustion amount in the furnace 10 as a whole decreases, and the pressure in the furnace 10 (furnace pressure) decreases, the amount of cooling air "Air" that is not used for combustion and intrudes into the furnace 10 through the cooling air supply pipe 60 (intrusion cooling air amount) increases, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 increases.

[0040] Furthermore, when the oxygen concentration in the furnace 10 increases, the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to each air ratio control system 50 of each burner 20 that is continuing to burn through the output control device 52, and converted into the air ratio in the furnace 10. The flow rate regulating valve 41 provided in the air supply pipe 40 of each burner 20 that is continuing to burn is adjusted by each air ratio control system 50, such as Figure 5 and Figure 6 As shown, the air ratio μE in each burner 20 that is continuing to burn is Figure 4The air ratio μD in the burner 20 shown is reduced (μD>μE), and the oxygen concentration in the furnace 10 is restored to the original oxygen concentration, thereby restoring the air ratio in the furnace 10.

[0041] In this way, even when combustion in some of the burners 20 is stopped, the oxygen concentration in the furnace 10 can be restored to the original oxygen concentration, and the air ratio in the furnace 10 can be quickly stabilized, so that the fuel gas G can be stably combusted.

[0042] In addition, in the combustion device of the second embodiment, Figure 5 As shown in FIG. 1 , the state in which the combustion in a part of the burners 20 is stopped is as follows: Figure 4 As shown in FIG. 1 , 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 opened relative to the burner 20 that has stopped combustion, and the fuel gas G and the combustion air Air are guided to the fuel gas supply nozzle 21 and the combustion air supply nozzle 23, and combustion is performed in all the burners 20. In this case, as shown in FIG. Figure 7 As shown, the overall combustion volume of the furnace 10 increases, and the pressure in the furnace 10 (furnace pressure) increases, the amount of cooling air "Air" that is not used for combustion and intrudes into the furnace 10 through the cooling air supply pipe 60 (intrusion cooling air amount) decreases, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 decreases.

[0043] Furthermore, when the oxygen concentration in the furnace 10 decreases, the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is output to each air ratio control system 50 of each burner 20 through the output control device 52, and converted into the air ratio in the furnace 10. The flow rate regulating valve 41 provided in the air supply pipe 40 of each burner 20 is adjusted by each air ratio control system 50, such as Figure 4 and Figure 7 As shown, the air ratio μD in each burner 20 is Figure 5 The original air ratio μE in the burner 20 that is performing combustion shown increases (μE<μD), so that the oxygen concentration in the furnace 10 returns to the original oxygen concentration, and the air ratio in the furnace 10 is restored.

[0044] In this way, when the combustion in a part of the burners 20 that have stopped combustion is restarted, the oxygen concentration in the furnace 10 can be restored to the original oxygen concentration, the air ratio in the furnace 10 can be quickly fixed, and the fuel gas G can be stably burned.

[0045] In addition, in the combustion equipment of the above-mentioned embodiments 1 and 2, when the ratio of the fuel gas G supplied to the burner 20 through the fuel supply pipe 30 and the combustion air Air supplied to the burner 20 through the air supply pipe 40 is adjusted by the air ratio control system 50, if the air ratio μ in the burner 20 is too low, the following problems will occur: the fuel gas G supplied to the burner 20 is not fully burned by the combustion air Air and unburned gas is generated, and the unburned gas is discharged from the furnace 10 to the outside, or soot generated by incomplete combustion adheres to the treated object, etc. Therefore, it is preferred that, when the ratio of the fuel gas G supplied to the burner 20 through the fuel supply pipe 30 and the combustion air Air supplied to the burner 20 through the air supply pipe 40 is adjusted by the air ratio control system 50, the lower limit value of the air ratio μ in the burner 20 is set so that the air ratio μ in the burner 20 does not become below the lower limit value.

[0046] Furthermore, in the combustion equipment of the above-mentioned first and second embodiments, the fuel gas G is used as the fuel, but the fuel is not limited to the gaseous fuel gas G, and a liquid fuel may also be used. Explanation of symbols

[0047] 10 furnaces 11 Opening 12 doors 13 wall 20 burners 21Fuel gas supply nozzle 22 Cooling air guide pipe 23 Combustion air supply nozzle 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 60 Cooling air supply pipe 61 valve Air Combustion air Air' intrusion Air" cooling air G Fuel Gas μ(μA, μB, μC, μD, μE) is the air ratio inside the burner.

Claims

1. A combustion device, wherein the ratio of fuel supplied through a fuel supply pipe and combustion air supplied through an air supply pipe is adjusted by an air ratio control system and supplied to a burner, and the combustion air and fuel are ejected from the burner into a furnace for combustion, wherein: An oxygen concentration sensor is provided for detecting a change in the oxygen concentration in the furnace caused by a change in the amount of air intruding into the furnace. The oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output control device to the air ratio control system. Based on the oxygen concentration in the furnace detected by the oxygen concentration sensor, the ratio of the combustion air and the fuel supplied to the burner is adjusted by the air ratio control system. When the fuel and the combustion air are burned in the furnace, the amount of the combustion exhaust gas in the furnace increases due to an increase in the combustion amount in the burner, the pressure in the furnace becomes higher, and the amount of the air intruding into the furnace decreases. In this case, the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases. The air ratio control system adjusts the ratio of the combustion air and the fuel supplied to the burner to increase the air ratio in the burner. On the other hand, when the amount of the combustion exhaust gas in the furnace decreases due to a decrease in the combustion amount of the burner, the pressure in the furnace decreases, the amount of intrusion air in the furnace increases, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the air ratio control system adjusts the ratio of the combustion air and the fuel supplied to the burner to decrease the air ratio in the burner.

2. A combustion device, wherein the ratio of fuel supplied through a fuel supply pipe and combustion air supplied through an air supply pipe is adjusted by an air ratio control system and supplied to a burner, so that the combustion air and fuel are ejected from the burner into a furnace for combustion, characterized in that: An oxygen concentration sensor is provided for detecting changes in the oxygen concentration in the furnace caused by changes in the amount of air intruding into the furnace, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output control device to the air ratio control system, and the ratio of combustion air and fuel supplied to the burner is adjusted by the air ratio control system based on the oxygen concentration in the furnace detected by the oxygen concentration sensor. A plurality of burners are provided in the furnace, each burner is provided with a cooling air guide pipe for guiding cooling air on the periphery of a fuel supply nozzle for supplying fuel, and a combustion air supply nozzle for supplying combustion air is provided on the periphery of the cooling air guide pipe. When the number of burners that stop combustion increases, the cooling air from the burners that have stopped combustion is increased. When the amount of cooling air intruding into the furnace through the cooling air guide pipe increases and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner that is currently burning, thereby reducing the air ratio in the burner that is currently burning. On the other hand, when the number of burners that have stopped burning decreases, the amount of cooling air intruding into the furnace from the cooling air guide pipes in the burners that have stopped burning decreases and the oxygen concentration in the furnace detected by the oxygen concentration sensor decreases, the air ratio control system adjusts the ratio of combustion air and fuel supplied to the burner that is currently burning, thereby increasing the air ratio in the burner that is currently burning.

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