JPS6335891B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a combustion control method in a combustion furnace,
More specifically, the present invention relates to a combustion control method in a combustion furnace that performs combustion control by measuring micro-pressure vibrations of each burner in the combustion furnace. When burning various fuels in burners in various industrial combustion furnaces, combustion management is currently very strict from the viewpoint of energy conservation and prevention of pollution caused by the generation of nitrogen oxides (NOx) and smoke. management is required. Combustion improvement technologies from an energy-saving perspective include the introduction of oxygen analyzers, cascade control that corrects the air ratio in proportion to fuel flow rate, and pattern control of input heat amount using computers. In addition, studies are underway to optimize combustion by controlling furnace pressure, the amount of liquid fuel atomized, burner position, and various flow rates. Combustion improvement technologies such as those mentioned above aim to effectively utilize the heat generated in the furnace, but the basic technology of directly grasping and controlling the combustion state inside the furnace has not yet been established. . For this reason, even if effective combustion improvement technology is applied to actual furnaces, which have many fluctuation factors, sufficient results are often not achieved. Even in corrective control, various problems have arisen in practical use due to the distribution of exhaust gas and the influence of air entering from the outside that does not contribute to combustion within the furnace. Therefore, the present inventors used a combustion test furnace to conduct detailed observations and studies on the combustion state under various combustion conditions, and found that micro-pressure oscillations of approximately 20 mm (water column) or less overlapped with the pressure inside the furnace. After further research, we discovered that the flame shows a certain change depending on the fluctuation of combustion conditions, and as a result of further research, we found that The combustion state, such as the amount, is clearly reflected in the micro-pressure vibration pattern in the furnace, and the power spectrum density distribution obtained by converting the micro-pressure vibration signal can be used practically effectively as an indicator for determining the combustion state. I found out what can be done. Based on this new knowledge, the applicant of the present application proposed a combustion state determination method for quantitatively determining the combustion state in a furnace based on a vibration pattern of minute pressure overlapping with the furnace pressure in Japanese Patent Application No. 122229/1982. , in Japanese Patent Application No. 17585/1985, describes an air ratio control method in a combustion furnace that controls the amount of air and other combustion improvers based on pressure vibrations in the furnace that occur during combustion or minute pressure vibration patterns that are superimposed on the pressure in the furnace. Also,
In Japanese Patent Application No. 54-36510, we proposed a method for controlling the combustion state in a combustion furnace in which the amount of atomization is controlled based on the oscillation of the pressure inside the furnace that occurs during combustion or the oscillation pattern of the minute pressure superimposed on the pressure inside the furnace. Furthermore, in Japanese Patent Application No. 54-34764, the tip position of the burner in the burner tile is automatically adjusted based on the detected value of the pressure vibration in the furnace that occurs during combustion or the vibration pattern of minute pressure superimposed on the pressure in the furnace. In Japanese Patent Application No. 54-43889, a method for controlling the combustion state in a combustion furnace is described, in which the combustion sound generated during combustion is measured, and the combustion state is determined based on its frequency characteristics or the synthesized sound pressure level. The patent application filed in 1983 describes a combustion state determination method and a control method for controlling the desired combustion state by adjusting the air ratio, the atomization amount of the high-pressure air flow oil burner, or the burner position, which directly affects the combustion state. −
In No. 92084, we proposed a signal processing method that converts the vibration pattern of minute pressure superimposed on the furnace pressure into a combustion state control signal. By the way, there are various types of industrial furnaces that have two or more burners per furnace, such as large boilers, various heating furnaces, heat treatment furnaces, melting furnaces, etc.
Conventionally, in such furnaces, individual burners have not been controlled due to equipment investment and maintenance considerations, but fuel, air volume, atomization volume, etc., have been controlled by controlling the entire burner or several burners as a set. Was. As mentioned above, in a furnace having two or more burners per furnace, the above invention proposed by the applicant is applied, and all or some of the burners are combined into a set by a micro pressure vibration pattern in the furnace. When controlling the fuel, air amount, atomization amount, etc., the following problems arise. Since the combustion state differs depending on the burner, it is easy to cause uneven heat in the furnace, and uneven heating in heating equipment and melting furnaces causes a decrease in quality yield. If even one burner has a poor combustion condition, it is necessary to perform combustion control in accordance with that burner, resulting in poor fuel consumption, lowering efficiency in boilers, etc., and shortening the life of equipment. Even if variations in the combustion state are adjusted when a certain amount of fuel is consumed, if the flow level changes, the balance will be lost again. In order to solve these problems,
It would be possible to ascertain the combustion status of each burner and install a control device on each burner, but doing so would require a huge amount of capital investment and the equipment would be complicated.
Not only is there a restriction on where the control device can be installed, but maintenance becomes extremely troublesome. The present invention has been made in view of the above-mentioned problems in various industrial furnaces having two or more burners.
The micro-pressure vibrations of each burner are measured by a micro-pressure vibration measurement probe installed inside the furnace in front of the burner tip, and the signals representing the combustion state obtained are averaged, and the average value is used as an index to By controlling the ratio, burner position, atomization amount in the case of liquid fuel, flow rate of fuel and combustion air, or primary air for combustion state control, the burner is maintained in the optimal combustion state and the amount of fuel used is reduced. With,
By detecting and displaying burner abnormalities from the variation in the average value of individual signals representing the combustion state obtained from each burner, abnormal burners can be detected early, preventing local overheating and humidity reduction, and ensuring uniform An object of the present invention is to provide a combustion control method in a combustion furnace that performs heating. Hereinafter, the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 shows the configuration of a control system for a combustion furnace that implements the method of the present invention. In FIG. 1, 1 is a combustion furnace section, 2 is a micro-pressure vibration measuring section, 3 is a signal preprocessing section that performs preliminary processing of vibration signals and converts the processing results into signals that can be processed by a computer, which will be described later, and 4 is a computer section. , 5 is a combustion state monitor section, 6 is a combustion control section, and 7 is an abnormal burner display section. The combustion furnace 11 of the combustion furnace section 1 is not limited in type or type, and may be any furnace such as a boiler, various heating furnaces, melting furnaces, heat treatment furnaces, etc. as long as it has multiple burners. Generally, FIG. 1 assumes a furnace having n burners. The micro-pressure vibration measurement unit 2 is a part that measures the combustion state by micro-pressure vibration, and corresponds to n burners.
Micro-pressure vibration measurement probes 12-1, 12-2,...,
12-n, detectors 13-1, 13-2,..., 13
-n and amplifiers 14-1, 14-2,..., 14
-consists of n. In addition, when determining the combustion state of each of the n burners, the sampling position, that is, the micro-pressure vibration measurement probes 12-1, 12-2, ..., 12-
The installation position of the probes 12-1, 12-2, ..., 12-n is important, and if the tips of these probes 12-1, 12-2, ..., 12-n enter too far into the furnace, they may detect the combustion status of other burners. I don't like it. The above micro-pressure vibration measurement probe 12-1, 12-
2,...,12-n should be inserted from the air throat of each burner, and the condition that the tip should be pulled 0 mm to 500 mm before the burner tip (inside the furnace) is to avoid the influence of other burners. It can be said to be optimal because of the lack of heat and temperature issues. In addition, sufficient measurement is possible even near the inner surface of each burner tile furnace. The signal preliminary processing section 3 includes a scanner 15, a micro-pressure vibration signal processing device 16, and an A/D converter 17. Micro-pressure vibration measurement probe 12-1, 12-2,
..., 12-n respectively measured signals from the 1st channel to the nth channel are input to the scanner 15, and the scanner 15 outputs amplifiers 14-1, 14-2, . . .
Each output of 14-n is sequentially connected to the micro-pressure vibration signal processing device 16 for a certain period of time. The operation of the scanner 15 is controlled by signals from the computer 18 of the computer section 4. The micro-pressure vibration signal processing device 16 is a device that converts the vibration pattern into an effective value expressed by the following first equation, and calculates the combustion state R _E defined by the second equation,
The details are explained in Japanese Patent Application No. 55-92084. However, in the first equation above, P _RMS is the effective value of vibration, P is the instantaneous value of vibration, T is integration time, and t is time. Combustion state R _E =integral value of high-range micro-vibration amplitude/integral value of micro-pressure vibration amplitude in low-range or entire range...(2) In order to calculate the second equation, the above-mentioned micro-pressure vibration signal processing device 16 , has the functions of effective value conversion and division, but as in the control system in Figure 1, a computer 1 is installed at the subsequent stage.
8, it is preferable that the calculator 18 executes necessary calculations such as the above-mentioned division, and that the micro-pressure vibration signal processing device 16 executes up to conversion of effective values. The output of the above-mentioned micro-pressure vibration signal processing device 16 is A/
The analog signal is converted into a digital signal by the D converter 17 and read into the computer 18. The computer section 4 includes a computer 18 and a setting input device 1.
9, a start button 20 and a timer 21. The start button 20 is a switch that generates an operation start signal for the control system shown in FIG. 1, and may also be used to start combustion or generate other signals, or may be linked. Further, the timer 21 is used to delay the time from the operation of the start button 20 to the start of actual control of the combustion furnace, and has a function of excluding an unstable period at the time of ignition from the control period. The setting input device 19 is a device for inputting measurement conditions and calculation conditions by the calculator 18, and here it is used to set the upper and lower limits of the vibration input signal for the purpose of removing abnormal signals that are too small or too large, and to input the settings for multiple burners. Setting the number n of burners to average the combustion states of (can also be set automatically with the calculator 18), setting the difference value (deviation value) between the average value of the combustion states and the combustion state of each burner, which will be described later. , setting the time constant and scanning time of the scanner 15, etc. The computer 18 operates according to the flowchart shown in FIG. 4, and the details of the operation will be explained later. Note that the line 22 from the computer 18 to the micro-pressure vibration signal processing device 16 is a line for sending a signal from the computer 18 to the numerator side or the denominator side of the second equation. A line 23 to the computer 15 is a line for transmitting a signal for specifying a channel for data acquisition from the computer 18 to the scanner 15. The combustion state monitor unit 5 is a part that monitors the combustion state of each burner, and includes memories 24-1, 24-2,
..., 24-n, D/A converter 25-1, 25-
2,..., 25-n, monitor device 26-1, 26-
It consists of 2,...,26-n. The calculator 18 calculates the second equation from the 1st channel to the nth channel to calculate the combustion states R _E1 , R _E2 ,
..., R _Eo is calculated and output signals are output in order as digital signals, so the signals of each channel are intermittent. Therefore, the combustion states R _E1 , R _E2 , ..., R _Eo output from the computer 18 at a certain timing are changed to
They are stored in the memories 24-1, 24-2, . . . , 24-n until R _E1 , R _E2 , . . . , R _Eo are sequentially output. D/A converter 25-1, 25-2,..., 25-
n is the memory 24-1, 24-2,..., 24-
converts the digital signal output from n into an analog signal. Monitor device 26-1, 26-2,..., 26-n
Since the combustion state is converted into an analog signal of 0 volts to 1 volt, any display device suitable for the purpose may be used, such as a recorder or a level meter. The combustion control section 6 includes a memory 30 and a D/A converter 3.
1, controller 32, lower limiter 33, control valve 3
4, consists of a flow meter 35 and a control line 36. The memory 30 and D/A converter 31 include memories 24-1, 24-2,..., 24-n and D/A converters 25-1, 25-2,..., 25-n.
It is set up for the same purpose. The output signal of the average combustion state _E from the computer 18 is converted into an analog signal by the D/A converter 31 and input to the controller 32. If the value R _B of the combustion state considered to be optimal is set in advance, the above-mentioned controller 32 compares it with the signal of the average combustion state _E and operates the control valve 34 according to the deviation. The lower limiter 33 is provided to prevent troubles in combustion control, and limits the operating range of the control valve 34 in consideration of safety. For example, the lower limiter 33 is set to a valve opening of 30%. If this is set, even if a signal is received from the controller 32 to throttle the control valve 34 below, the valve opening will remain constant at 30%, thereby preventing troubles such as smoke and burner damage. In addition, it is preferable that the controller 32 is equipped with a hard manual setting, and when the control target is the amount of atomization, the control stop button 32 is used.
It is preferable to have a function of fully opening the control valve with the signal No. 7 and purging the inside of the burner. The control stop button 37 may be provided independently, but may also be used together with or linked to a heavy oil cutoff switch. Control line 3 from flow meter 35 to combustion furnace 11
6 represents an atomizing medium, a combustion air line, etc. The abnormal burner display section 7 indicates the combustion state R _Ei (i=1,
2,..., n) is out of the range _E -K≦R _Ei ≦ _E +K.
0, alarm display device 41-1, 41-2,..., 41
-consisting of n, these alarm display devices 41-
1, 41-2, . . . , 41-n are for notifying the furnace operator of a malfunctioning burner by, for example, a lamp display, a patrol light, or a buzzer. With the control system shown in FIG. 1 described above, optimal combustion control of each burner in the combustion furnace section 1 can be performed in the following manner. That is, the amplifiers 14-1, 1 of the micro-pressure vibration measuring section 2
Each output of 4-2,..., 14-n is sent to the scanner 15.
The signals are sequentially scanned and input to the differential amplifier 4a of the input section 1a of the micro-pressure vibration signal processing device 16. The above-mentioned micro-pressure vibration signal processing device 16 is most effective when configured as shown in FIG. I will explain about it. As shown in FIG. 2, the micro-pressure vibration signal processing device 16 includes an input section 1a and a signal processing section 2a. The input section 1a includes amplifiers 14-1, 14-2 of the micro-pressure vibration measuring section 2 which receive input from the scanner 15,
..., 14-n as a voltage signal, an AC coupling circuit 5a that blocks the DC component of the output signal of the differential amplifier 4a, and an amplifier 6a for gain adjustment. Consisting of The input resistance of the differential amplifier 4a is switched between two types, for example, 220Ω and 220kΩ, depending on whether the preamplifier is a current output type or a voltage output type. Also, the amplifier 6
A is designed to attenuate or amplify the signal input from the AC coupling circuit 5a by 1/2, 1, 2 or 4 to adjust the level of the output signal from the AC coupling circuit 5a. Next, the signal processing unit 2a includes a low-pass filter 7a that passes through the entire frequency band a signal necessary for determining the combustion state among the signals input from the amplifier 6a, and an output of the low-pass filter 7a. Among the signals, a low-pass filter 8a passes a signal with a low frequency component corresponding to micro-pressure vibrations that grow during slow combustion determined in advance. Among the output signals of the low-pass filter 7a, the signal passing through the low-pass filter 8a A high pass filter 9 that also passes signals having high frequency components.
a, an absolute value averaging circuit 10a that averages each output signal of the low-pass filter 8a and high-pass filter 9a and converts it into a DC signal;
and 11a, a divider 12a that divides the output of the absolute value averaging circuit 11a by the absolute value averaging circuit 10a to detect the vibration energy ratio R _E of the high frequency component and the low frequency component of the micro-pressure vibration. . In the signal processing section 2a, the low-pass filter 7a has cut-off frequencies of 250Hz, 500Hz and
While switching to 3 stages of 1000Hz,
Another low-pass filter 8a is zero Hz,
The high pass filter 9a has 6 levels of 50Hz, 75Hz, 100Hz, 125Hz, and 150Hz.
The cutoff frequency can be switched in five stages: 75Hz, 100Hz, 125Hz, and 150Hz, allowing optimal signal processing to be performed depending on the target combustion furnace. That is, in the micro-pressure signal processing device 16, as shown in FIG. 3A, the output signal of the differential amplifier 4a having a DC component is input to the AC coupling circuit 5a, and as shown in FIG. 3B, The DC component caused by the pressure inside the furnace is removed, and only the micro-pressure vibration component is extracted. Among the micro-pressure vibration components outputted from the AC coupling circuit 5a, high frequency component signals unnecessary for determining the combustion state are removed, and then the output signals are input to a low-pass filter 8a and a high-pass filter 9a. Next, the low-pass filter 8a filters the predetermined low-frequency band components of micro-pressure vibrations that grow during slow combustion (see Fig. 3 E).
While extracting from the output signal of a, the high-pass filter 9a extracts a frequency band component of micro-pressure vibration higher than the low frequency band component (see Fig. 3 C).
is extracted from the output signal of the low-pass filter 7a. The output signal of the low-pass filter 8a is rectified and smoothed by an absolute value averaging circuit 10a.
The signal is converted into a DC signal as shown in FIG. Further, the output signal of the high-pass filter 9a is rectified and smoothed by an absolute value averaging circuit 11a, and converted into a DC signal as shown in FIG. 3D. After that, each of these DC signals is input to the computer 18, and the DC signal output from the absolute value averaging circuit 11a is divided by the output of another absolute value averaging circuit 10a, and the low frequency component of the micro-pressure vibration in the furnace is Find the vibrational energy ratio R _E of this and higher frequency components. That is, the computer 18 calculates the combustion state using the second equation.
_When expressing R _E , in step 101 of the flowchart in FIG.
The division of the second equation is executed, and the result is output to the combustion state monitor section 5. Next, in step 103, when it is determined that the above-mentioned division has been executed for 1 to n channels, in step 104, the average value _E of the combustion state of 1 to n channels is calculated, and the result is Outputs as a 4mA to 20mA control signal. Next, in step 105, the value of the coefficient (for example, 0.05 to 0.5) input in advance with the setting input device 19 is read, and in step 106, the combustion state R _Ei of each burner is compared with _E ±K, and R _Ei is ,
When the signal deviates from the range of R _E -KR _{Ei E} +K, a signal is output that activates the alarm device of that channel i. The optimal combustion control target of the computer 18 that operates as described above is, as already mentioned, the amount of combustion air,
Examples include the atomized amount of liquid fuel, burner position, furnace pressure, and primary air for controlling the combustion state of the gas burner. That is, to control the burner position, the control valve 34 may be replaced with a burner drive device to control the burner position, and to control the inside of the furnace, a damper for adjusting the furnace pressure provided in the flue may be controlled. . Further, the control valve 34 can be used for controlling primary air or steam for controlling the combustion state of the gas burner. As an example of a furnace in which primary air or steam for controlling the combustion state of the gas burner is controlled by a control valve 34, FIG. 5 shows a structural diagram of a gas burner whose combustion state can be controlled. In FIG. 5, 42 is a high-pressure air or steam line, 43 is a pressure gauge, 44 is a primary air line for combustion state control, 45 is a gas fuel line, 46 is a gas burner, 47 is a combustion air line, and 48 is an air regulator. 49 is a baffle, 50 is a burner tile, 12 is a micro-pressure vibration probe, and 13 is a detector. In the gas burner shown in FIG. 5, the mixing state of the fuel and combustion air changes greatly depending on the flow rate and flow velocity of the primary air amount, and the combustion state also changes accordingly. As described above, the object to be controlled is not particularly limited, and any object whose combustion state can be changed can be controlled. The following modifications of the control system shown in FIG. 1 can be considered. When the number of burners is large, it is possible to apply a method in which all the burners are divided into several blocks and only the computer 18 is shared for control, or a similar method can be applied in which several burners are used as representatives. It can also be used as an independent device, such as only determining the variation in the combustion state of each burner and displaying abnormal burners, or only controlling combustion based on the average value of the combustion state. Regarding the vibration measurement of each burner, the control system shown in Figure 1 is equipped with a probe sensor and an amplifier for each burner, but if there are many burners, only the probe is installed on each burner as shown in Figure 6. There is also a method in which each probe is connected to the pressure switching valve 51 by a conduit, and the parts after the detector are shared. In this case, the detector 13 and the amplifier 14
is only the number of divided burners (in the example, 1
), and Sukiyana can also be omitted. Note that the pressure switching valve is operated by a signal from the computer 18. In the control system shown in Fig. 1, the abnormal burner is determined by giving the absolute value of K and determining _E −K≦R _Ei ≦ _E +K, but the combustion state of each burner R _Ei (i=1, n)
Find the standard deviation α of the variation _{of E} −K′α
The determination may be made using ≦R _Ei ≦ _E +K′α. However, K′=1 to 3 is appropriate. Depending on the furnace, you may want to consciously change the combustion state by changing the amount of combustion. In this case, a cascade control method may be applied in which the fuel flow rate signal is input to the controller and the set value is corrected in proportion to the flow rate. Next, when the present invention was applied to a forging cart type heating furnace shown in FIGS. 7a and 7b equipped with a plurality of burners, the following results were obtained. However, in FIGS. 7a and 7b, 60 is a charging/extraction door, 61 is a trolley, 62 is a raw material, 63 is a burner tile, 64 is a burner, 65 is a furnace temperature measurement hole,
66 is an exhaust gas outlet, 67 is a flue, 68 is a damper for adjusting furnace pressure, and 69 is a pillow. The main specifications of the above-mentioned forging trolley heating furnace are shown in Table 1 below.

[Table] Note that the amount of air in the forging cart type heating furnace is controlled by one main valve, and the amount of atomization is not controlled and remains constant. FIG. 8 shows an example of the results of monitoring the combustion state of each burner 64 by controlling the above-mentioned forging trolley heating furnace using the control system shown in FIG. 1. In Figure 8, T is the furnace temperature (°C) and Q is the fuel flow rate (/
h), R _E is the combustion state of each burner 64 defined by the second equation, and R _E1 , R _E2 , R _E3 and R _E4 are the combustion states of burners 64-1, 64-2, 64-3 and 64-4.
This is a curve showing the combustion state of . However, in Fig. 8, burners 64-5, 6
Since burner 4-6 showed almost the same combustion state as burner 64-2, its curve was omitted. As can be seen from FIG. 8, the combustion states R _E1 and R _E3 of burner 64-1 and burner 64-3 deviate from the overall trend, indicating that an abnormality has occurred. When burner 64-1 was investigated at stage _S1 when the abnormality occurred, the fuel nozzle was found to be clogged with foreign matter. For this reason, the fuel flow rate was lower than that of other burners, and since the atomization amount was constant, the relative atomization amount increased, and the combustion state suddenly changed, so the value of the combustion state R _E increased. It is something that According to the inspection results in step _S2 , burner 64-3 had deposits on the tip of the burner tip. As a result, the combustion state seems to have become extremely slow. It can be seen that after inspection and maintenance, all burners returned to normal and the combustion state was similar to that of other burners. In addition, in the forging trolley-type heating furnace shown in Figures 7a and 7b, the combustion changes rapidly during fuel turndown (the value of the combustion state R _E increases).
It has characteristics. We found that this was most likely due to the effect of keeping the atomization amount constant even when the fuel level decreased.
We decided to control the amount of atomization. FIG. 9 shows the results of combustion state control and burner variation determination control. As can be seen from Fig. 9, burners 64-1, 64
-2, ..., 64-7 are all values of almost constant combustion state R _E1 , R _E2 , ..., R _E7 ,
In stage _S3 , the combustion state R _E4 of burner 64-4 is _E −
It is clear that although the alarm was issued when the temperature deviated from K, it has become constant after inspection and maintenance of burner 64-4. In addition, also in FIG. 9, the combustion states R _E6 and R _E7 of the burners 64-6 and 64-7 are omitted because they are the same combustion states as the burner 64-1 etc. In addition, as can be seen from Fig. 9, the combustion state R _E1 ,
Although the overall level of R _E2 ,..., R _E5 has increased,
This is because the lower limiter of the control system shown in FIG. 1 operates to keep the atomization amount constant. As described above, it has become possible to control the combustion state of a multiple burner furnace and to detect abnormal burners at an early stage. The present invention makes it possible to maintain optimal combustion conditions and achieve uniform heating, reducing fuel consumption by 12%. Furthermore, local overheating can be prevented, improving quality and yield. In addition, by controlling the amount of atomization
NOx was also reduced by 20%. As is clear from the detailed explanation above, the present invention is an industrial furnace having a plurality of burners. Since the combustion state of the entire burner is controlled using the average value of the signal representing the combustion state obtained as a result of measurement with the pressure vibration measuring probe, the measured value of the micro-pressure vibration of each burner can be used as an index. The effect of micro-pressure oscillations is reduced, and the micro-pressure oscillation measurements of each burner are highly reliable, which allows the burner to maintain optimal combustion conditions as a whole and significantly reduces fuel consumption. In addition, burner abnormalities are detected and displayed from the variation in the average value of individual signals representing the combustion state of each burner, so abnormal burners can be detected early and localized overheating and temperature drops can be prevented. The quality and yield of products produced by the furnace to which the present invention is applied can be greatly improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control system to which the present invention is applied in a multiple burner furnace, Fig. 2 is a block diagram of a micro-pressure vibration signal processing device, and Fig. 3 A to T are signal processing of each part of Fig. 2. Explanatory diagram showing waveforms, 4th
The figure is a flowchart of calculations executed by the computer in Figure 1, Figure 5 is an explanatory diagram showing the structure of a gas burner to which the present invention is applied, and Figure 6 is a control example when a micro-pressure vibration detector is shared. A partial block diagram of the system, FIGS. 7a and 7b are a partially sectional front view and a partially sectional side view showing the structure of a cart-type heating furnace, respectively. FIG. 8 is a partial block diagram of the cart-type heating furnace shown in FIGS. 7a and b, respectively. FIG. 9 is a monitor diagram of the combustion state in the furnace during control in the trolley-type heating furnace shown in FIGS. 7a and 7b, respectively. DESCRIPTION OF SYMBOLS 1... Combustion furnace section, 2... Micro-pressure vibration measurement section, 3... Signal preprocessing section (4a... Differential amplifier, 5a... AC coupling circuit, 6a... Amplifier, 7a, 8a... Low pass filter, 10a, 11a... Absolute value averaging circuit, 12a...divider), 4...computer section, 5...combustion state monitor section, 6...combustion control section, 7...display section of abnormal burner.

Claims (1)

[Claims] 1. In a combustion furnace having multiple burners, the micro-pressure vibration of each burner is measured with a micro-pressure vibration measurement probe installed inside the furnace from the tip of the burner, and the combustion state of each burner is detected, Average the micro-pressure vibration signals obtained from each burner, control combustion in each burner based on that value, and further compare the individual signals obtained from each burner with the average value, A method for controlling combustion in a combustion furnace, characterized in that when the difference is greater than a certain value, a message indicating that the burner is abnormal is displayed.