Combustion equipment

Abstract

The present invention uses an air ratio control system 50 to adjust the ratio of fuel gas G to combustion air Air supplied to burner 20. When the fuel gas and combustion air are burning in furnace 10, the oxygen concentration in the furnace detected by oxygen concentration sensor 51 is output to the air ratio control system via output control device 52, and the ratio of fuel gas to combustion air supplied to burner is adjusted. On the other hand, when the oxygen concentration in the furnace detected by oxygen concentration sensor changes significantly, the detected oxygen concentration in the furnace is not output to the aforementioned air ratio control system via output control device, and the ratio of fuel gas to combustion air supplied to burner is maintained by the air ratio control system.

Description

combustion equipment The present invention relates to a combustion apparatus in which the ratio of gaseous or liquid 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 fuel and combustion air are ejected from the burner into a furnace for combustion. In particular, the apparatus has the following features: Even in situations where the amount of air entering the furnace fluctuates significantly when the furnace door is opened or closed, and the oxygen concentration within the furnace fluctuates significantly, the ratio of fuel to combustion air supplied to the burner can be appropriately controlled, thereby achieving stable and good combustion conditions. 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 for combustion. Here, in order to make the fuel and combustion air become a predetermined air ratio in the furnace, as shown in Patent Document 1, a furnace using a regenerative burner is shown, in which the actual flow coefficient of the burner is determined by measuring the pressure and valve opening, and the burner flow coefficient is operated so as to conform to the measured value of the state change of the fluid, and the air ratio in the furnace is kept constant to control the combustion amount. However, in the method shown in Patent Document 1, the actual flow coefficient of the burner is determined by measuring the pressure and the valve opening, and the burner is operated so that the flow coefficient of the burner conforms to the measured value of the state change of the fluid. Therefore, for example, when the furnace door is opened and closed, the amount of intruding air intruding into the furnace will change greatly. When the oxygen concentration in the furnace changes greatly, it is very difficult to quickly respond and keep the air ratio in the furnace constant. For example, when the furnace door is opened, the amount of intruding air intruding into the furnace increases greatly. In order to keep the air ratio in the furnace constant, if the proportion of combustion air supplied to the burner is reduced, and the air ratio in the burner is greatly reduced, unburned gas will be ejected from the burner, and soot or carbon monoxide will be easily generated, which may reduce safety during operation or cause adverse effects on products or the environment. Furthermore, in the past, as shown in Patent Document 2, a method for operating a continuous heating furnace having a plurality of combustion zones and having combustion burners is shown, in which when the burners of a part of the combustion zones are operated in a flameout or low-load state, a target value of at least the oxygen concentration in the combustion zone is obtained, and the air ratio of each combustion zone on the upstream side is controlled based on the target value, and an oxygen concentration meter and a CO concentration meter are provided on the combustion gas exhaust side of each combustion zone, and when the burners of a part of the combustion zones are operated in a flameout or low-load state, a target value of at least the oxygen concentration in the combustion zone is obtained, and the air ratio of each combustion zone on the upstream side is obtained based on the target value, and either the CO concentration target value or the oxygen concentration target value is set according to the obtained 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 aforementioned oxygen concentration meter and CO concentration meter. However, as described in Patent Document 2, an oxygen concentration meter and a CO concentration meter are provided on the combustion gas exhaust side of each combustion zone, and when the burners of a part of the combustion zone are operated in a flameout or low-load state, a target value of at least the oxygen concentration in the combustion zone is obtained. The air ratio of each combustion zone on the upstream side is calculated based on the target value. Therefore, the amount of intrusion air invading the furnace will vary greatly, similar to when the furnace door is opened and closed as shown in the aforementioned patent document 1. When the oxygen concentration in the furnace varies greatly, it is very difficult to quickly respond and keep the air ratio in the furnace constant. For example, in a furnace equipped with multiple burners, the combustion of some burners is stopped, and only cooling air for preventing thermal deformation of the fuel nozzle flows into the furnace, thereby greatly increasing the amount of intrusion air invading the furnace. In order to keep the air ratio in the furnace constant, if the proportion of combustion air supplied to the burner is reduced, and the air ratio of the burner is greatly reduced, unburned gas will be ejected from the burner, and soot or carbon monoxide will be easily generated, which may reduce the safety of the operation or cause adverse effects on the product or the environment. [Prior Art Literature] [Patent Document] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-103461 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-26815 The object of the present invention is to solve the above-mentioned problems and to provide 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, from which the fuel and combustion air are ejected into a furnace and burned by setting the fuel and combustion air to an appropriate air ratio in the furnace. That is, the subject of the present invention is that in the combustion equipment as described above, when the furnace door is opened and closed, the amount of intruding air into the furnace will change greatly. When the oxygen concentration in the furnace changes greatly, the ratio of fuel supplied to the burner and combustion air can also be properly controlled to stably obtain a good combustion state. In the combustion equipment related to the present invention, in order to solve the above-mentioned problems, 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 combustion air are ejected from the burner into the furnace and burned. In the combustion equipment, an oxygen concentration sensor for detecting the oxygen concentration in the furnace is provided, and the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system by an output control device, and the ratio of the fuel supplied to the burner and the combustion air is adjusted by the air ratio control system. On the other hand, due to the opening of the door provided in the furnace, the intrusion into the furnace is When the amount of air introduced increases and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, the oxygen concentration in the furnace detected by the aforementioned oxygen concentration sensor is not output to the aforementioned air ratio control system by the aforementioned output control device, but the ratio of the fuel supplied to the burner and the combustion air is maintained by the aforementioned air ratio control system. On the other hand, when the aforementioned door is closed and the oxygen concentration in the furnace detected by the aforementioned oxygen concentration sensor returns to a predetermined value, the oxygen concentration in the furnace detected by the aforementioned oxygen concentration sensor is output to the aforementioned air ratio control system by the aforementioned output control device, and the ratio of the fuel supplied to the aforementioned burner and the combustion air is controlled by the aforementioned air ratio control system. Then, in the combustion equipment of the present invention, as mentioned 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 air ratio control system is used to adjust the amount of fuel and combustion air supplied to the burner. Therefore, in situations where the oxygen concentration in the furnace may change, the air ratio control system is used to adjust the ratio of fuel and combustion air supplied to the burner in such a way that the oxygen concentration in the furnace does not change. In this way, the air ratio in the furnace can be made to a predetermined value and stable combustion can be performed. On the other hand, when the door of the furnace is opened, the amount of air intruding into the furnace increases, and when 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 the fuel supplied to the burner and the combustion air is maintained by the air ratio control system. Therefore, when the door of the furnace is opened, when the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, the ratio of the fuel supplied to the burner and the combustion air can also be maintained by the air ratio control system. The air ratio control system does not cause the ratio of the combustion air supplied to the burner to decrease significantly, and prevents the fuel from being incompletely burned (that is, becoming incompletely burned), and prevents unburned gas from being discharged from the furnace to the outside, or generating coal ash or carbon monoxide. Furthermore, when the door is closed and the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a predetermined value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system by the output control device. The air ratio control system controls the ratio of the fuel supplied to the burner to the combustion air to the original state, thereby enabling the air ratio in the furnace to be set to the original predetermined value for stable combustion. In the combustion equipment of the present invention, as mentioned 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 air ratio control system adjusts the amount of fuel and combustion air supplied to the burner. Therefore, when the oxygen concentration in the furnace changes, the ratio of fuel and combustion air supplied to the burner can be adjusted by the air ratio control system, so that the air ratio in the furnace can be set to a predetermined value to perform stable combustion. On the other hand, when the door of the furnace is opened and the amount of intruding air into the furnace increases, 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 by the output control device, and the ratio of fuel supplied to the burner and combustion air 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 a predetermined value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system by the output control device, and the air ratio control system is maintained. The gas ratio control system controls the ratio of the fuel and combustion air supplied to the aforementioned burner. Therefore, when the door of the furnace is opened and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, the ratio of the combustion air supplied to the burner does not decrease significantly, resulting in incomplete combustion of the fuel. This can prevent unburned gas from being discharged from the furnace to the outside, or the generation of coal ash or carbon monoxide. At the same time, when the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a predetermined value, the air ratio control system can control the ratio of the fuel supplied to the aforementioned burner to the original state. Therefore, the air ratio in the furnace can be set to the original predetermined value to achieve stable combustion. As a result, in the combustion equipment of the present invention, when the furnace door is opened or closed, the amount of intruding air into the furnace changes greatly, and when the oxygen concentration in the furnace changes greatly, the ratio of fuel supplied to the burner to combustion air can be properly controlled to obtain a stable and good combustion state. 10: Furnace 11: Opening 12: Door 20: Burner 30: Fuel supply pipe 31: Flow adjustment valve 40: Air supply pipe 41: Flow adjustment valve 50: Air ratio control system 51: Oxygen concentration sensor 52: Output control device Air: Combustion air Air': outside air G: Fuel gas FIG1 is a schematic diagram showing a state in which an oxygen concentration sensor is used to detect the oxygen concentration in a furnace in a combustion device according to an embodiment of the present invention, the detected oxygen concentration in the furnace is output to an air ratio control system via an output control device, and the air ratio control system adjusts the ratio of fuel gas and combustion air supplied to a burner as fuel, thereby causing the fuel gas and combustion air to be ejected from the burner into the furnace and burned. Figure 2 is a schematic diagram illustrating a state in which, in the combustion equipment of the aforementioned embodiment, (A) is a diagram showing a state in which, when the door provided in the furnace is opened and the oxygen concentration in the furnace detected by the oxygen concentration sensor increases significantly, the oxygen concentration detected by the oxygen concentration sensor is not output to the air ratio control system by the output control device, but the ratio of the fuel gas and combustion air supplied to the burner is maintained by the air ratio control system and the burner is burned; and (B) is a diagram showing a state in which, when the door is opened as described above is closed and the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a predetermined value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is not output to the air ratio control system by the output control device, but the ratio of the fuel gas and combustion air supplied to the burner is maintained by the air ratio control system and the burner is burned. Figure 3 is a timing diagram showing the change in oxygen concentration in the furnace detected by the oxygen concentration sensor and the state of the air ratio in the burner at the time when the switch is installed on the furnace door and the time when the output control device outputs ON / OFF to the air ratio control system in the combustion equipment of the aforementioned embodiment. The combustion equipment according to the present invention is described in detail below with reference to the accompanying drawings. Furthermore, the combustion equipment according to the present invention is not limited to the embodiments shown below, but can be implemented with appropriate modifications within the scope of the invention. In the combustion equipment of this embodiment, as shown in Figure 1, a burner 20 is provided in a furnace 10 having a door 12 for opening and closing an opening portion 11. In the aforementioned burner 20, fuel gas G such as urban gas, which is a fuel, is supplied via a fuel supply pipe 30, and combustion air Air is supplied via an air supply pipe 40, and the combustion air Air and the fuel gas G are ejected from the burner 20 into the furnace 10 and burned. Next, in the combustion equipment of this embodiment, as described above, when the burner 20 supplies fuel gas G through the fuel supply pipe 30 and supplies combustion air Air through the air supply pipe 40, the air ratio control system 50 adjusts the flow adjustment valve 31 provided on the aforementioned fuel supply pipe 30 and the flow adjustment valve 41 provided on the air supply pipe 40 to control the ratio of the fuel gas G and combustion air Air supplied to the burner 20, and adjusts the air ratio in the burner 20 to a predetermined value, and the fuel gas G and combustion air Air are ejected from the burner 20 into the furnace 10 and burned. Furthermore, the combustion equipment of this embodiment is equipped with an oxygen concentration sensor 51 for detecting the oxygen concentration within the furnace 10. The oxygen concentration within the furnace 10 detected by the oxygen concentration sensor 51 is output to the aforementioned air ratio control system 50 via an output control device 52. Based on the output oxygen concentration within the furnace 10, the air ratio control system 50 adjusts the flow rate control valve 31 provided in the fuel supply pipe 30 and the flow rate control valve 41 provided in the air supply pipe 40, thereby controlling the ratio of the fuel gas G and the combustion air Air supplied to the burner 20, thereby adjusting the air ratio in the burner 20 to a predetermined value. FIG. 1 shows a state in which the output control device 52 is connected to the air ratio control system 50. Then, in the combustion equipment of this embodiment, as shown in FIG2(A), if 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, and the oxygen concentration in the furnace 10 detected by the aforementioned oxygen concentration sensor 51 will increase significantly. Here, when the oxygen concentration in such a furnace 10 increases significantly, as mentioned above, the oxygen concentration in the furnace 10 is output to the air ratio control system 50 by the output control device 52, 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 air ratio in the furnace 10 becomes a predetermined value, and the amount of combustion air Air supplied to the burner 20 is significantly reduced. The fuel gas G supplied to the burner 20 is not completely burned, and unburned gas remains in the furnace 10 and is discharged to the outside, or ash or carbon monoxide is generated. Therefore, in the combustion equipment of this embodiment, when the door 12 of the furnace 10 is opened and a large amount of outside air Air' flows into the furnace 10 through the opening 11 of the furnace 10, and the oxygen concentration within the furnace 10 detected by the oxygen concentration sensor 51 increases significantly, as shown in Figures 2(A) and 3, the output control device 52 is turned OFF, and the oxygen concentration within the furnace 10 detected by the oxygen concentration sensor 51 is not output to the air ratio control system 50. Furthermore, the ratio of the fuel gas G to the combustion air Air supplied to the burner 20 is not changed by the air ratio control system 50, and the air ratio within the burner 20 is kept constant. In this way, when the oxygen concentration within the furnace 10 increases significantly, as described above, the amount of combustion air Air supplied to the burner 20 does not decrease significantly, and incomplete combustion of the fuel gas G supplied to the burner 20 is prevented. 2 (A) and FIG. 2 (B) described later, the output control device 52 and the air ratio control system 50 are shown to be in a disconnected state. Furthermore, as shown in FIG. 2(B) and FIG. 3 , even when the door 12 of the open furnace 10 is closed and the flow of outside air Air' from the furnace 10 into the furnace 10 is stopped, if the oxygen concentration within the furnace 10 detected by the oxygen concentration sensor 51 is high, the output control device 52 remains in the OFF state, and the oxygen concentration within the furnace 10 detected by the oxygen concentration sensor 51 is not output to the air ratio control system 50. Furthermore, at this time, the oxygen concentration sensor 51 continuously monitors the oxygen concentration within the furnace 10. Next, as mentioned above, the door 12 of the furnace 10 is closed, and when the oxygen concentration in the furnace 10 detected by the oxygen concentration sensor 51 returns to a predetermined value, as shown in Figures 1 and 3, the output control device 52 is set to 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 air ratio is released. The air ratio control system 50 adjusts the flow adjustment valve 31 provided on the fuel supply pipe 30 and the flow adjustment valve 41 provided on the air supply pipe 40 to control the ratio of the fuel gas G supplied to the burner 20 and the combustion air Air, so that the air ratio in the burner 20 is adjusted to a predetermined value. Here, in the combustion equipment of this embodiment, the time point at which the aforementioned output control device 52 is set to OFF can be set to be simultaneous with the time point at which the door 12 of the furnace 10 is opened, as shown in FIG3 . However, the time point at which the output control device 52 is set to OFF can also be set to be before the door 12 of the furnace 10 is about to be opened, or just after the door 12 of the furnace 10 is opened. In addition, in the combustion equipment of this embodiment, although the switch is shown to be located on the door 12 of the furnace 10 as a situation where the oxygen concentration detected by the oxygen concentration sensor 51 changes significantly, the situation where the oxygen concentration detected by the oxygen concentration sensor 51 changes significantly is not limited to this. For example, although not shown in the figure, multiple burners having cooling air supply pipes on the periphery of the fuel nozzles of the burners for preventing thermal deformation are installed in the furnace. In the combustion equipment in which combustion is performed by each burner, the combustion of one or more burners is stopped while combustion is being performed in each burner, and a large amount of cooling air is supplied to the furnace through the cooling air supply pipes on the periphery of the fuel nozzles in each stopped burner. Even in a case where the oxygen concentration detected by the oxygen concentration sensor increases significantly, control can be performed in the same manner as in the aforementioned embodiment.

Claims

1. A combustion device in which the ratio of fuel supplied via a fuel supply pipe to combustion air supplied via an air supply pipe is adjusted by an air ratio control system and supplied to a burner, from which fuel and combustion air are ejected into a furnace for combustion. The combustion device includes an oxygen concentration sensor for detecting the oxygen concentration inside the furnace, and the oxygen concentration detected by the oxygen concentration sensor is output to the air ratio control system via an output control device. The air ratio control system adjusts the ratio of fuel to combustion air supplied to the burner. Furthermore, by opening the furnace door, the amount of intrusion air entering the furnace increases. When 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 by the output control device. Instead, the air ratio control system maintains the ratio of fuel to combustion air supplied to the burner. On the other hand, when the door is closed and the oxygen concentration in the furnace detected by the oxygen concentration sensor returns to a predetermined value, the oxygen concentration in the furnace detected by the oxygen concentration sensor is output to the air ratio control system by the output control device. The air ratio control system then controls the ratio of fuel to combustion air supplied to the burner.

2. The combustion apparatus as described in claim 1, wherein, The point at which the oxygen concentration inside the furnace detected by the aforementioned oxygen concentration sensor is not output to the aforementioned air ratio control system by the aforementioned output control device is set just before the aforementioned door is about to be opened.

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