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 combusted in a furnace (10), the oxygen concentration in the furnace detected by an oxygen concentration sensor (51) is output to the air ratio control system by an output control device (52). Adjusting the ratio of the fuel gas to the combustion air supplied to the combustor; on the other hand, when the oxygen concentration in the furnace detected by the oxygen concentration sensor changes greatly, the detected oxygen concentration in the furnace is not output to the air ratio control system by the output control device, but the ratio of the fuel gas to the combustion air supplied to the burner is maintained by the air ratio control system.

Description

Technical Field

[0001] The present invention relates to a combustion device, which adjusts the ratio of gaseous or liquid 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 and combustion air to a burner, so that the fuel and combustion air are ejected from the burner into a furnace for combustion. In particular, the device has the following characteristics: even when the amount of intruding air intruding into the furnace changes greatly, such as when the furnace door is opened and closed, so that the oxygen concentration in the furnace changes greatly, the ratio of fuel and combustion air supplied to the burner can be properly controlled, and a good combustion state can be stably obtained. 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 combustion is carried out in the furnace in such a manner that the fuel and combustion air become a specified air ratio, Patent Document 1 shows the following: In a furnace using a regenerative burner, the pressure and valve opening are measured to determine the actual flow coefficient of the burner, whereby the flow coefficient of the burner can be treated as a measured value that matches the state change of the fluid, and the combustion amount can be controlled while keeping the air ratio in the furnace constant.

[0004] However, in the content shown in Patent Document 1, the actual flow coefficient of the burner is determined by measuring the pressure and the valve opening, and the flow coefficient of the burner is treated as a measured value that matches the state change of the fluid. Therefore, for example, when the amount of intruding air into the furnace changes greatly and the oxygen concentration in the furnace changes greatly, such as when the furnace door is opened and closed, it is difficult to respond quickly and make the air ratio in the furnace constant. For example, when the amount of intruding air into the furnace increases greatly by opening the furnace door, if the proportion of combustion air supplied to the burner is reduced in order to make the air ratio in the furnace constant, so that the air ratio in the burner is greatly reduced, unburned gas will be ejected from the burner, soot and carbon monoxide are likely to be generated, and there is a problem of reduced safety during operation or adverse effects on products and the environment.

[0005] In addition, in the past, Patent Document 2 showed the following: In an operating method of a continuous heating furnace having multiple combustion zones with fuel burners, when the burners of a part of the combustion zones are extinguished or operating at a low load, a target value of at least the oxygen concentration in the combustion zone is calculated, and the air ratio of each combustion zone on the upstream side is controlled based on the target value; and the following is shown: an oxygen concentration meter and a CO concentration meter are set on the combustion exhaust gas outlet side of each combustion zone, and when the burners of a part of the combustion zone are extinguished or operating at a low load, a target value of at least the oxygen concentration in the combustion zone is calculated, and the air ratio of each combustion zone on the upstream side is calculated based on the target value, and either the CO concentration target value or the oxygen concentration target value is set in accordance with the calculated air ratio, and either the oxygen concentration or the CO concentration is controlled based on the set target value and the measured values ​​of the oxygen concentration meter and the CO concentration meter.

[0006] However, in the content shown in the comparative document 2, as described above, an oxygen concentration meter and a CO concentration meter are set on the combustion exhaust gas outlet side of each combustion zone, and when the burner of a part of the combustion zone is extinguished or operated at a low load state, a target value of at least the oxygen concentration in the combustion zone is calculated, and the air ratio of each combustion zone on the upstream side is calculated based on the target value. Therefore, similar to the case of opening and closing the furnace door as shown in the patent document 1, when the amount of intruding air intruding into the furnace changes significantly and the oxygen concentration in the furnace changes significantly, it is difficult to respond quickly and make the air ratio in the furnace constant. For example, in a furnace provided with multiple burners, because the combustion of some burners is stopped, only cooling air for preventing thermal deformation of the fuel nozzle flows into the furnace, causing the amount of intruding air intruding into the furnace to increase significantly. If the proportion of combustion air supplied to the burner is reduced in order to make the air ratio in the furnace constant, so that the air ratio in the burner is greatly reduced, unburned gas will be ejected from the burner, soot and carbon monoxide are likely to be generated, and there are problems of reduced safety during operation or adverse effects on products and the environment. Prior art literature Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 7-103461 Patent Document 2: Japanese Patent Application Publication No. 2001-26815 Summary of the invention Technical problem to be solved by the invention

[0008] 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 fuel and combustion air to a burner, sprays the fuel and combustion air from the burner into a furnace, and burns the fuel and combustion air in the furnace at an appropriate air ratio.

[0009] That is, the subject of the present invention is that, in the above-mentioned combustion equipment, even when the amount of air intruding into the furnace changes greatly and the oxygen concentration in the furnace changes greatly, such as when the furnace door is opened and closed, the ratio of fuel and combustion air supplied to the burner can be properly controlled to stably obtain a good combustion state. Technical solutions adopted to solve technical problems

[0010] In the combustion equipment of the present invention, in order to solve the above-mentioned problems, an oxygen concentration sensor for detecting the oxygen concentration in 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, and the fuel and the combustion air are ejected from the burner into the furnace for combustion. The oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through an output control device, and the ratio of the fuel and the combustion air supplied to the burner is adjusted by the air ratio control system. On the other hand, when the amount of intrusion air intruding into the furnace changes due to opening the door provided in the furnace, On the other hand, when the door is closed and the oxygen concentration in the furnace detected by the oxygen concentration sensor is restored to a specified value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through the output control device, and the ratio of fuel and combustion air supplied to the burner is controlled by the air ratio control system.

[0011] Furthermore, in the combustion equipment of the present invention, as described above, the oxygen concentration in the furnace is detected by the oxygen concentration sensor, and the oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output device to the air ratio control system. The amount of fuel and combustion air supplied to the burner is adjusted by the air ratio control system. Therefore, in a case where the oxygen concentration in the furnace may change, the ratio of fuel and combustion air supplied to the burner is adjusted by the air ratio control system in a manner that keeps the oxygen concentration in the furnace unchanged, thereby enabling the air ratio in the furnace to become a specified value and stable combustion to be performed.

[0012] On the other hand, when the amount of intruding air into the furnace increases due to opening the door provided in the furnace, thereby significantly increasing the oxygen concentration in the furnace detected by the oxygen concentration sensor, the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system through the output control device, but the ratio of the fuel and combustion air supplied to the burner is maintained by the air ratio control system. Therefore, even if the door provided in the furnace is opened and the oxygen concentration in the furnace detected by the oxygen concentration sensor is significantly increased, the ratio of the fuel and combustion air supplied to the burner is maintained by the air ratio control system, and the ratio of the combustion air supplied to the burner is not significantly reduced due to the air ratio control system, thereby preventing incomplete combustion of the fuel (i.e., incomplete combustion), discharge of unburned gas from the furnace to the outside, or generation of soot and carbon monoxide.

[0013] Furthermore, when the door is closed so that the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a specified value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through the output control device, and the ratio of the fuel and combustion air supplied to the burner is controlled as it is by the air ratio control system. Therefore, the air ratio in the furnace can be made to be the specified value as it is, thereby performing stable combustion. Effects of the Invention

[0014] In the combustion equipment of the present invention, as described above, the oxygen concentration in the furnace is detected by the oxygen concentration sensor, and the oxygen concentration in the furnace detected by the oxygen concentration sensor is output from the output device to the air ratio control system, and the amount of fuel and combustion air supplied to the burner is adjusted by the air ratio control system. Therefore, even if the oxygen concentration in the furnace changes, the ratio of fuel and combustion air supplied to the burner is adjusted by the air ratio control system, so that the air ratio in the furnace can be made to be a specified value and stable combustion can be performed. On the other hand, when the amount of intrusion air into the furnace increases due to the opening of the door provided in the furnace, and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system through the output control device, but the ratio of fuel and combustion air supplied to the burner is maintained by the air ratio control system; on the other hand, when the door is closed and the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to the specified value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through the output control device, and the air ratio control system is adjusted. The control system controls the ratio of fuel and combustion air supplied to the burner. Therefore, even if the door of the furnace is opened, which greatly increases the oxygen concentration in the furnace detected by the oxygen concentration sensor, the ratio of combustion air supplied to the burner will not be greatly reduced or the fuel will not be completely burned. This can prevent unburned gas from being discharged from the furnace to the outside, or soot and carbon monoxide from being generated. Furthermore, when the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a specified value, the air ratio control system controls the ratio of fuel and combustion air supplied to the burner as it is. Therefore, the air ratio in the furnace can be kept at the specified value as it is, thereby achieving stable combustion.

[0015] As a result, in the combustion equipment of the present invention, even when the amount of air intruding into the furnace changes greatly, causing the oxygen concentration in the furnace to change greatly, such as when the furnace door is opened and closed, the ratio of fuel and combustion air supplied to the burner can be properly controlled, thereby stably obtaining a good combustion state. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram showing the following state: In the combustion equipment of the embodiment of the present invention, the oxygen concentration in the furnace is detected by an oxygen concentration sensor, the detected oxygen concentration in the furnace is output to the air ratio control system by the output control device, and the ratio of the fuel gas and the combustion air supplied to the burner as fuel is adjusted by the air ratio control system, so that the fuel gas and the combustion air are ejected from the burner into the furnace and burned. Figure 2(A) is a schematic diagram showing a state in which, in the combustion equipment of the embodiment, when a door provided in the furnace is opened so that the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, combustion is performed by maintaining the ratio of fuel gas and combustion air supplied to the burner by the air ratio control system in a manner that the oxygen concentration detected by the oxygen concentration sensor is not output to the air ratio control system through the output control device; Figure 2 (B) is a schematic diagram showing the following state: in the combustion equipment of the embodiment, the door that is in the open state as described above is closed until the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a specified value, and combustion is performed by maintaining the ratio of fuel gas and combustion air supplied to the burner through the air ratio control system in a manner such that the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system through the output control device. Figure 3 It is a timing diagram showing the timing of opening and closing the door provided in the furnace in the combustion equipment of the embodiment, the timing of turning on / off the output of the output control device to the air ratio control system, the changing state of the oxygen concentration in the furnace detected by the oxygen concentration sensor, and the state of the air ratio in the burner. DETAILED DESCRIPTION

[0017] 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.

[0018] In the combustion device of this embodiment, if Figure 1 As 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.

[0019] Furthermore, in the combustion equipment of 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 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, and the air ratio in the burner 20 is adjusted to a specified value, so that the fuel gas G and the combustion air Air are ejected from the burner 20 into the furnace 10 and burned.

[0020] Furthermore, in the combustion equipment of the present 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, 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 supplied to the burner 20 and the combustion air Air, and the air ratio in the burner 20 is adjusted to a specified value. In addition, in Figure 1 , a state in which the output control device 52 is connected to the air ratio control system 50 is shown.

[0021] Furthermore, in the combustion device of this embodiment, if Figure 2 As shown in (A), when the door 12 of the furnace 10 is opened, a large amount of external air Air' outside the furnace 10 flows into the furnace 10 through the opening 11 of the furnace 10, so that the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 increases significantly.

[0022] Here, when the oxygen concentration in the furnace 10 increases so significantly, the oxygen concentration in the furnace 10 is output to the air ratio control system 50 through the output control device 52 as described above, and the ratio of the fuel gas G and the combustion air Air supplied to the burner 20 is controlled by the air ratio control system 50, so that the amount of combustion air Air supplied to the burner 20 is significantly reduced in such a way that the air ratio in the furnace 10 becomes a specified value. As a result, the fuel gas G supplied to the burner 20 is no longer completely burned, and the following problems may occur: unburned gas remains in the furnace 10 and is discharged to the outside, or soot and carbon monoxide are generated.

[0023] Therefore, in the combustion equipment of this embodiment, when the door 12 of the furnace 10 is opened, the external air Air' outside the furnace 10 flows into the furnace 10 through the opening 11 of the furnace 10 in large quantities, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 increases significantly, as shown in FIG. Figure 2 (A) and Figure 3 As shown, the output control device 52 is set to OFF, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is not output to the air ratio control system 50. The ratio of the fuel gas G and the combustion air Air supplied to the burner 20 is not changed through the air ratio control system 50, and the air ratio in the burner 20 is fixed to be constant. In this way, when the oxygen concentration in the furnace 10 increases significantly, the amount of the combustion air Air supplied to the burner 20 will not decrease significantly as described above, and incomplete combustion of the fuel gas G supplied to the burner 20 can be prevented. In addition, Figure 2(A) and the following Figure 2 (B) shows a case where the output control device 52 and the air ratio control system 50 are in a cut-off state.

[0024] In addition, if Figure 2 (B) and Figure 3 As shown, when the door 12 of the furnace 10 opened as described above is closed and the flow of the external gas Air' outside the furnace 10 into the furnace 10 is stopped, even when the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is at a high state, the output control device 52 is maintained in a closed state, and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is not output to the air ratio control system 50. In addition, at this time, the oxygen concentration sensor 51 continues to monitor the oxygen concentration in the furnace 10.

[0025] Furthermore, when the door 12 of the furnace 10 is closed as described above and the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 is restored to a predetermined value, Figure 1 and Figure 3 As shown, the output control device 52 is turned on, 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, and the fixation of the air ratio is released. 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 supplied to the burner 20 and the combustion air Air, and the air ratio in the burner 20 is adjusted to a specified value.

[0026] Here, in the combustion device of this embodiment, Figure 3 As shown, the time when the output control device 52 is closed is the same as the time when the door 12 of the furnace 10 is opened, but the time when the output control device 52 is closed can also be set to be just before the door 12 of the furnace 10 is opened or just after the door 12 of the furnace 10 is opened.

[0027] In the combustion equipment of this embodiment, as a case where the oxygen concentration detected by the oxygen concentration sensor 51 changes significantly, the case where the door 12 provided in the furnace 10 is opened and closed is shown, but the case where the oxygen concentration detected by the oxygen concentration sensor 51 changes significantly is not limited to this.

[0028] For example, although not shown in the figure, a furnace is provided with multiple burners each having cooling air supply pipes provided on the periphery of the fuel nozzle of the burner for preventing thermal deformation. In the combustion equipment that performs combustion through each burner, control can be performed in the same manner as in the above-described embodiment in the following situation: starting from a state in which combustion is in progress in each burner, combustion in one or more burners is stopped, a large amount of cooling air is supplied into the furnace through the cooling air supply pipes located on the periphery of the fuel nozzle in each stopped burner, and the oxygen concentration detected by the oxygen concentration sensor increases significantly. Explanation of symbols

[0029] 10 furnaces 11 Opening 12 doors 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 Air'Outside air G Fuel gas.

Claims

1. A combustion device, The combustion equipment adjusts the ratio of the fuel supplied through the fuel supply pipe and the combustion air supplied through the air supply pipe through the air ratio control system and supplies the fuel and the combustion air to the burner, and sprays the fuel and the combustion air from the burner into the furnace for combustion, and is characterized in that: An oxygen concentration sensor is provided for detecting the oxygen concentration in the furnace, and the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through an output control device, and the ratio of the fuel and combustion air supplied to the burner is adjusted by the air ratio control system; on the other hand, when the amount of intruding air into the furnace increases due to opening the door provided in the furnace, thereby significantly increasing the oxygen concentration in the furnace detected by the oxygen concentration sensor, the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system through the output control device, but the ratio of the fuel and combustion air supplied to the burner is maintained by the air ratio control system; on the other hand, when the door is closed, so that the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a specified value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system through the output control device, and the ratio of the fuel and combustion air supplied to the burner is controlled by the air ratio control system.

2. The combustion device according to claim 1, characterized in that: The timing at which the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system via the output control device is set to be immediately before the door is opened.

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