JPH1061941A - Device and method for alternate combustion control of heat storage type burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the control of combustion safely even when abnormality is generated in the combustion of a heat storage type burner. SOLUTION: A heating furnace 1 is provided with a heat storage type burner 3, receiving a heat storage body 20, a fuel shut-off valve 18 is connected to a fuel nozzle 13 for the heat storage type burner 3, a pipeline, connected to the heat storage type burner 3, is branched while an air shut-off valve 14 and an exhaust gas shut-off valve 16 are connected to each branched pipe and a pilot burner 30 is provided with a flame failure detector 31. When the flame failure detector 31 has detected the flame failure of the heat storage type burner, only the fuel shut-off valve 18 of the heat storage type burner 3 is intercepted to continue alternate combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for alternating combustion of a regenerative burner, and more particularly, to a combustion control capable of coping with an ignition failure when an ignition failure occurs during alternating combustion of a regenerative burner. The present invention relates to an alternating combustion control device for a regenerative burner and a method for maintaining safety by the method.

[0002]

2. Description of the Related Art In general, when a regenerative burner is used in a heating furnace, a pair of regenerative burners are arranged on a furnace wall of the heating furnace so as to face each other, and combustion and exhaust of combustion exhaust gas (sensible heat of combustion exhaust gas) are performed. (Accumulation in the gas) is alternately performed.

FIG. 6 shows an outline of a combustion apparatus using a regenerative burner in a conventional heating furnace. The regenerative burner 3
The heating furnace 1 is mounted on furnace walls 2 facing each other. The regenerative burner 3 includes a burner tile 3a provided on the furnace wall 2, an air nozzle 3b provided inside the furnace provided on the burner tile 3a, a fuel nozzle 8 opened on the air nozzle 3b, and a fuel nozzle 8 provided on the burner tile 3a. It is composed of a pilot burner 9 provided adjacently and a heat storage body 20.

[0004] A temperature detector 21 is provided on the outlet side of the combustion exhaust gas of the regenerator 20, and a misfire detection device 10 is provided on the pilot burner 9. The fuel nozzle 8 is provided with a fuel cutoff valve 7, and a pipe connected to the regenerative burner 3 is provided with an air cutoff valve 5 and an exhaust gas cutoff valve 6. The air cutoff valve 5, the exhaust gas cutoff valve 6, and the fuel cutoff valve 7 are controlled by control signals from the control device 4. The outputs from the misfire detection device 10 and the temperature detector 21 are input to the control device 4. The illustration of the air flow control valve, the exhaust gas flow control valve, and the fuel flow control valve is omitted.

Next, a conventional method for controlling alternating combustion of a regenerative burner will be described with reference to FIGS. The flowchart of FIG. 7 shows a combustion control method when a regenerative burner generates abnormal combustion. In step S1, the pair of regenerative burners 3 are ignited to start alternating combustion, and the temperature inside the heating furnace 1 is raised. Thereafter, the heating furnace 1 shifts to a steady operation. Proceeding to step S2, it is determined whether or not to continue the alternating combustion. If not, the fuel supplied to the regenerative burner 3 is gradually reduced to terminate the alternating combustion and terminate the operation of the heating furnace 1. . When the alternating combustion is to be continued, the process proceeds to step S3. In step S3, abnormal combustion of the regenerative burner 3 is periodically monitored, and if abnormal combustion is detected by the misfire detection device 10 or the like, the process proceeds to step S4. In step S4, the supply of fuel and combustion air into the heating furnace 1 is stopped by shutting off the air cutoff valve 5, the exhaust gas cutoff valve 6, and the fuel cutoff valve 7 of the regenerative burner 3 in which the combustion abnormality has occurred.

Next, a conventional combustion control device for eliminating abnormal combustion of a regenerative burner will be described with reference to FIG.
First, the alternating combustion will be briefly described. In one regenerative burner 3, the air cutoff valve 5 and the fuel cutoff valve 7 are opened, and fuel is supplied via the fuel cutoff valve 7.
The combustion air is preheated when passing through the regenerator 20 and supplied to the furnace for combustion. The exhaust gas shutoff valve 6 is shut off,
Maintain the combustion state for a certain time. The other regenerative burner 3
The air shutoff valve 5 and the fuel shutoff valve 7 are shut off, and the exhaust gas shutoff valve 6 is open. The exhaust gas is sucked, the combustion exhaust gas is in a discharge state for a certain time, and the sensible heat of the combustion exhaust gas is accumulated in the heat storage unit 20. By alternately repeating such a state, the energy recovery efficiency is increased.

In such alternating combustion, a pair of regenerative burners alternately repeats combustion and accumulation of sensible heat of exhaust gas. When the furnace temperature is, for example, 800 ° C. or less, fuel and combustion air are exchanged. Even if the mixture is supplied into the heating furnace in which the gas is mixed, the self-stabilizing ignition cannot be performed because the temperature is lower than the natural ignition temperature, so that a pilot burner is required. If the pilot burner is misfired, ignition failure will occur and the heating furnace will be filled with unburned fuel gas more than allowable, or the fuel gas will be discharged outside the furnace and explode inside and outside the heating furnace. Abnormal combustion may occur due to such factors, and a problem may occur in terms of safety. Therefore, if the temperature inside the heating furnace is lower than the self-stable ignition temperature (spontaneous ignition temperature), if the pilot burner cannot be used due to malfunction of the misfire detection device, misfire of the pilot burner, etc. Combustion by the regenerative burner must be stopped. Until the self-stabilizing ignition temperature reaches the furnace temperature of 800 ° C. or higher, the air shutoff valve 5, exhaust gas shutoff valve 6, and fuel shutoff valve 7 of the regenerative burner are closed, and the furnace temperature is equal to or higher than the self-stabilizing ignition temperature Until the operation of combustion and heat storage is not performed, the operation is stopped.

[0008]

In the conventional combustion control of a regenerative burner, the temperature in the furnace is set to a self-stable ignition temperature (for example,
If the temperature is in a low temperature range of 800 ° C. or lower, the operation is stopped from the viewpoint of safety. The temperature of the heating furnace is raised by continuous operation of a normal regenerative burner or combustion by another normal burner. Since the regenerative burner in which the abnormality has occurred stops the combustion and the suction of the exhaust gas, and stops the heat storage operation, the temperature of the regenerator of the regenerative burner in which the combustion is stopped is substantially equal to a normal temperature. When normal alternating combustion is performed when the temperature in the heating furnace becomes 800 ° C. or higher, the high-temperature exhaust gas of 800 ° C. or higher is sucked into the heat storage body of the regenerative burner that has stopped burning. A steep temperature gradient is generated in the heat storage body, and an excessive thermal stress is applied to the heat storage body, which causes a crack in the heat storage body.

When the heat storage element 20 is damaged, the flow path of the combustion air and the exhaust gas is narrowed, the pressure loss by the heat storage element is increased, and the suction blower for supplying the combustion air and sucking the exhaust gas is driven. Power consumption may increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide an alternating combustion control device for a regenerative burner and a method thereof that can perform safe combustion control even if a combustion abnormality occurs. Is what you do.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and will be described with reference to the functional block diagram of FIG. The invention according to claim 1 is a combustion control device for a regenerative burner that alternately burns a regenerative burner by an alternating combustion control unit 25a, wherein a misfire detection unit 25c for detecting a misfire of the regenerative burner, Temperature detecting means 25b for detecting, an in-furnace temperature determining means 25d for determining whether or not the output from the temperature detecting means 25b has reached a spontaneous ignition temperature of the fuel; the misfire detecting means; and the in-furnace temperature determining means. And a combustion shutoff valve driving means 25e for operating a fuel shutoff valve of the regenerative burner to be misfired on the basis of 25d. By controlling the fuel cutoff valve 18 of the regenerative burner to be misfired by detecting the misfire detection means 25c and determining whether the furnace temperature has reached the spontaneous ignition temperature, the heating furnace It is an alternating combustion control device capable of maintaining safety.

According to a second aspect of the present invention, in the method for controlling alternating combustion of a regenerative burner, the temperature in the heating furnace is equal to or lower than the spontaneous ignition temperature of the fuel mixed with the combustion air, and the misfire is detected by the misfire detection device. If the regenerative burner becomes unusable due to malfunction of the detection or misfire detection device, or misfire of the pilot burner, etc., the fuel shutoff valve of the unusable regenerative burner is shut off, and the air shutoff valve and the exhaust gas shutoff valve are alternated. As in the case of the combustion, the operation is performed so as to supply the combustion air and suck the combustion exhaust gas, and when the temperature in the heating furnace reaches the self-ignition temperature or more, the shut-off fuel cutoff valve is opened to perform the alternating combustion. An alternating combustion control method for a regenerative burner, wherein misfire of a regenerative burner is detected by a misfire detecting means, and a misfire target is determined based on whether or not the furnace temperature has reached a spontaneous ignition temperature. And controls the fuel shut-off valve of regenerative burner, a combustion control method for safety can be maintained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a view showing an embodiment of an alternating combustion control device for a regenerative burner according to the present invention. In the figure, a heat storage body 20 is placed on a furnace wall 2 of a heating furnace 1.
A regenerative burner 3 equipped with a regenerative burner is usually mounted. In a heating furnace using a regenerative burner, a pair of regenerative burners perform a combustion operation as one unit, and a plurality of pairs of regenerative burners are provided in accordance with the inner volume of the heating furnace. A burner is provided. The regenerative burner 3 has a burner tile 11 embedded in a furnace wall 2 and a burner tile 1.
1 is provided with an air nozzle 12 opening inside the furnace, and a fuel nozzle 13 and a pilot burner 30 are provided in the air nozzle 12.
Is open. The temperature detector 21 is provided on the outlet side of the combustion exhaust gas, and a temperature detector 27 is provided in the heating furnace 1. A misfire detection device 31 is provided adjacent to the pilot burner 30.

The fuel nozzle 13 is connected to a fuel cutoff valve 18, and is connected to a fuel flow control valve 19 via a fuel flow meter 23. A pipe is connected to the regenerative burner 3, an air cutoff valve 14 is provided on one of the branched pipes, and an exhaust gas cutoff valve 16 is provided on the other branched pipe. The air cutoff valve 14 is connected to the air flow control valve 15 via the air flow meter 22.
The exhaust gas cutoff valve 16 is connected to an exhaust gas flow control valve 17 via an exhaust gas flow meter 24, and is connected to an exhaust gas suction blower 26.

The control device 25 is provided with arithmetic means, control means, and a storage device in which a control program is written. The control device 25 includes a temperature detector 27 for detecting the temperature in the heating furnace 1, a temperature detector 21 for measuring the temperature of the outlet side of the combustion exhaust gas of the regenerative burner 3, an air flow meter 22, a fuel flow meter 23, and An output from the exhaust gas flow meter 24 is input, and based on a control signal from the control device 25, the air cutoff valve 14, the air flow control valve 15, the exhaust gas cutoff valve 1
6. The exhaust gas flow control valve 17, the fuel cutoff valve 18, and the fuel flow control valve 19 are controlled.

Next, an embodiment of an alternating combustion control method according to the present invention will be described with reference to the flowchart of FIG. In this figure, step S1 is a step of alternatingly burning a pair of regenerative burners 3 provided in the heating furnace 1. The pair of regenerative burners 3 is stored in a storage device of the control device 25 according to a control program. This is a step of performing alternating combustion based on the above. As described above, in the alternating combustion, one regenerative burner is set to a combustion state, and the other regenerative burner discharges exhaust gas, that is, exhaust gas is discharged outside the furnace while preheating the regenerator by sensible heat of the exhaust gas. And This is a combustion method in which these states are repeated while being alternately switched over a certain period of time.

Step S2 is a step of judging whether or not to continue the alternating combustion. When the operation of the heating furnace 1 is stopped, the fuel flow control valve 19 is operated to reduce the fuel supply amount. Terminate combustion. On the other hand, if the alternating combustion is to be continued, the process proceeds to step S3, where it is determined whether or not the regenerative burner has caused a combustion abnormality such as misfire. If no combustion abnormality has occurred, the process returns to step S1. If a combustion abnormality has occurred, the process proceeds to step S4. In step S4, it is determined whether or not the furnace temperature has reached the temperature at which the mixed gas of the fuel and the combustion air spontaneously ignites (natural ignition temperature or self-stable ignition temperature). If the furnace temperature and the spontaneous ignition temperature have a relationship of furnace temperature ≦ spontaneous ignition temperature, the process proceeds to step S5, and the fuel shut-off valve 18 of the regenerative burner in which the abnormality has occurred is shut off. On the other hand, the air shutoff valve 14 and the exhaust gas shutoff valve 16 of the regenerative burner in which an abnormality has occurred continue to open and close in an alternating combustion cycle.

In the alternating-current combustion control apparatus and method for a regenerative burner according to the present embodiment, two or more regenerative burners are arranged in a heating furnace, and the temperature (furnace temperature) in the furnace of the heating furnace is set to a value for combustion. Heat storage such as misfire detection by the misfire detection device 31, malfunction of the misfire detection device 31, and failure to use the pilot burner in a temperature range of not more than a natural ignition temperature (self-stable ignition temperature) of fuel mixed with air, for example, 800 ° C or less. When an abnormality occurs in the burner and its peripheral devices, the fuel shut-off valve 18 of the regenerative burner 3 is operated from the point of safety until the fuel mixed with the combustion air reaches a furnace temperature of 800 ° C. or higher at which self-stabilization ignition is possible. Is closed to shut off the supply of fuel to bring it into a non-combustion state. The suction of the combustion air and the exhaust gas from the furnace to the outside of the furnace is performed in the same manner as other normal regenerative burners. Thereby, the heat storage body 20 stores the sensible heat of the exhaust gas, and the heat storage body 20 of the heat storage type burner 3 that has stopped burning is heated. At the time when the furnace temperature becomes equal to or higher than the self-stable ignition temperature, when the fuel cutoff valve 18 is opened to start normal alternating combustion, the heat storage body 20 is heated, and a sharp temperature gradient occurs. Therefore, it is possible to prevent the heat storage body 20 from cracking due to thermal shock due to rapid thermal stress.

Next, with reference to FIGS. 4 and 5, there is shown a difference between the conventional example, the present invention, and the alternating combustion control. FIG.
(A) is a diagram showing the temperature measurement points of the heat storage body for verifying the effect of the present invention, and FIG. 4 (b) shows the relationship between the surface layer temperature of the heat storage body and time. FIG. 5 (a) is a diagram showing temperature measurement points on the input and output sides of the combustion exhaust gas of the regenerator for verifying the effect of the present invention, and FIG. 5 (b) shows the temperature gradient of the surface layer of the regenerator and the time. Shows the relationship.

FIG. 4A shows a change in the surface layer temperature of the conventional heat storage element, and FIG. 4B shows a change in the surface layer temperature of the heat storage element of the present invention. FIG. 4A shows a case in which the air shutoff valve 14, the exhaust gas shutoff valve 16, and the fuel shutoff valve 18 are operated when the furnace temperature reaches 800 ° C. In contrast, (b) shows the case of the present embodiment in which only the fuel cutoff valve 1 is shut off, and the temperature rise is smooth even when the fuel cutoff valve 18 is shut off. Even if the fuel cut-off valve 18 is opened to start combustion at the spontaneous ignition temperature when the furnace temperature reaches 800 ° C. or higher, no rapid temperature fluctuation occurs, This indicates that no stress is applied.

FIG. 5 (a) shows the relationship between the surface layer temperature gradient of the conventional heat storage element and time, and FIG. 5 (b) shows the relation between the surface layer temperature gradient and time of the heat storage element of the present invention. The temperature gradient was represented by X, where X is the length of the heat storage body in the direction in which the fluid flows, and dX is the unit length (1 / m). FIG. 5A shows a case in which the air shutoff valve 14, the exhaust gas shutoff valve 16, and the fuel shutoff valve 18 are operated to start alternating combustion when the furnace temperature reaches 800 ° C. In contrast to the steep temperature gradient, the present embodiment is a case where the fuel is alternately burned with only the fuel cutoff valve 1 shut off at the time of abnormality, and when the furnace temperature reaches 800 ° C., the fuel cutoff valve 18
In the case of starting the alternating combustion by opening the heat storage, as shown in (b), the temperature gradient is smooth, indicating that abnormal thermal stress is not applied to the heat storage body.

Of course, the furnace temperature may be detected by a temperature detector provided in the heating furnace, but the furnace temperature may be assumed by a temperature detector provided on the exhaust gas discharge side of the regenerative burner. It is clear.

[0023]

As described above, according to the present invention,
Even if the regenerative burner, which was stopped for safety in the alternating combustion of the regenerative burner, was supplied for fuel when the furnace temperature of the heating furnace reached the spontaneous ignition temperature to start the alternating combustion, even if the regenerative burner started There is an advantage that the occurrence of the occurrence can be prevented.

Further, according to the present invention, the life of the heat storage body can be extended, so that the cost can be reduced. Further, there is an advantage that it is possible to prevent an increase in power loss of the suction blower due to an increase in pressure loss when the combustion air and the exhaust gas pass due to cracks in the heat storage body, and to contribute to maintaining high efficiency of energy recovery of the heating furnace.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an alternating combustion device of a regenerative burner according to the present invention.

FIG. 2 is a view showing an embodiment of an alternating combustion device for a regenerative burner according to the present invention.

FIG. 3 is a flowchart illustrating an embodiment of a combustion control method for a regenerative burner according to the present invention.

FIG. 4 is a diagram showing a comparison between changes in the surface layer temperature of a heat storage body of the present invention and a conventional heat storage body.

FIG. 5 is a diagram showing a change in a surface layer temperature gradient of a heat storage body according to the present invention and a conventional example.

FIG. 6 is a view showing an example of a conventional regenerative burner alternating combustion device.

FIG. 7 is a flowchart showing an example of a conventional regenerative burner alternating combustion method.

[Explanation of symbols]

 Reference Signs List 1 heating furnace 2 furnace wall 3 regenerative burner 11 burner tile 12 air nozzle 13 fuel nozzle 14 air cutoff valve 15 air flow control valve 16 exhaust gas cutoff valve 17 exhaust gas flow control valve 18 fuel cutoff valve 19 fuel flow control valve 20 heat storage element 21 , 27 Temperature detector 22 Air flow meter 23 Fuel flow meter 24 Exhaust gas flow meter 25 Controller 26 Exhaust gas suction blower 30 Pilot burner 31 Misfire detector

Claims (2)

[Claims] 1. An alternating combustion control device for a regenerative burner, wherein misfire detecting means for detecting misfire of the regenerative burner, temperature detecting means for detecting a temperature in the heating furnace, and an output from the temperature detecting means. A furnace temperature determining unit for determining whether or not a spontaneous ignition temperature of the fuel has been reached, based on the misfire detecting unit and the furnace temperature determining unit,
A combustion shutoff valve driving means for operating a fuel shutoff valve of the regenerative burner to be misfired; and an alternating combustion control device for the regenerative burner. 2. A method for controlling alternating combustion in a regenerative burner, wherein the temperature in the heating furnace is equal to or lower than the spontaneous ignition temperature of fuel mixed with combustion air, and misfire detection by the misfire detection device or malfunction of the misfire detection device. If the regenerative burner becomes unusable due to misfire of the pilot burner, etc., the fuel shut-off valve of the unusable regenerative burner is shut off, and the air shut-off valve and the exhaust gas shut-off valve are used for combustion in the same manner as during alternating combustion. It is operated so as to supply air and suck combustion exhaust gas, and at the time when the temperature in the heating furnace reaches the self-ignition temperature or more, the fuel cutoff valve in a shut-off state is opened to perform alternating combustion. Combustion control method for regenerative burners.