JPH0820073B2 - Burner combustion controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a burner combustion control device used in combustion equipment such as a boiler.

(Prior Art) In a burner that burns liquid or gaseous fuel, it is desirable to always maintain a constant flame amount during burning. This control is especially necessary when the product is subjected to precise heat treatment by the heat generated by the burner. For this reason, various proposals have heretofore been made regarding burner combustion control methods. One of them uses steam pressure generated in a boiler (see Japanese Examined Patent Publication No. 62-10509). As another method, a power spectrum obtained by converting the light intensity signal generated by the burner flame into an electric signal using a semiconductor such as a phototransistor, a photodiode or a solar cell, and obtaining the frequency analysis result of the vibration waveform A method and an apparatus for controlling combustion by utilizing the integral value of is proposed (Japanese Patent Application No. 62-139456).

When the power spectrum change is used as the control signal like the latter one, as shown in FIG. 8, the integrated value B of the specific frequency band and the integrated value of the entire frequency band in which the power spectrum changes greatly due to the change of the combustion state. Ratio of A B /
The method of using A, the method of using the integrated value B of the specific frequency band as it is as shown in FIG. 9, and the maximum value C of all the frequency bands and the maximum of the specific frequency band as shown in FIG. The method of using the ratio D / C of the value D, the method of using the maximum value D in a specific frequency band as shown in FIG.
As shown in the figure, the method of using the ratio F / E of the average value E of all frequency bands and the average value F of the specific frequency band, and the average value F of the specific frequency band as it is as shown in FIG. Methods etc. were used.

(Problems to be Solved by the Invention) Next, problems in the above-described conventional technique will be described. As shown in Fig. 9, Fig. 11, and Fig. 13, when the output value is used as it is, it is possible to use the output value as the control signal, but the frequency range and power Because the spectrum range changes,
It becomes very difficult to set the output range of the control signal. When the ratio is used as shown in FIG. 8, FIG. 10 and FIG. 12, the maximum value is determined to be 100%, so the output range of the control signal should be set to 0 to 100%. Therefore, in the case of FIG. 8 and FIG. 12, although the values of the integrated value B and the average value F in the specific frequency band greatly change in the case of FIG. 8 and FIG. 12, they are the same as the denominator for obtaining the ratio. In some cases, the rate of change cannot be large because it changes. An example is shown in FIG.

In this case, if the amount (%) of the exhaust gas O ₂ which is one of the indicators of the combustion state is changed, the burner atomizing air pressure becomes 20%.
When the 00mmH ₂ O varies greatly, but was found to change if the 3000mmH ₂ O is very small. When the rate of change becomes small as described above, the influence of variation becomes large, and it becomes difficult to accurately grasp the combustion state. Further, in the case of FIG. 10, it is considered that there is usually no problem, but when the power supply noise is included in the optical power signal due to some influence, this power supply noise acts and as shown in FIG. 15 and FIG. There may be peaks other than the actual signal, and there are cases where it cannot be accurately determined.

As described above, the conventional method has many problems even though it can be used. The present invention aims to solve this problem.

(Means for Solving the Problems) As means for solving the above problems, the present invention detects an optical power of a flame 12 emitted from a burner 2 of a furnace 1 and outputs an optical power signal to an optical power receiving portion 13 of the flame. A frequency analyzer 14 that analyzes the frequency of the optical power signal output by the optical power receiver 13 and outputs an optical spectrum signal, and is provided between the optical power receiver 13 and the frequency analyzer 14. The cutoff unit 20 that periodically cuts off the optical power signal from the power receiving unit 13, and the output signal of the frequency analyzer 14 when the optical power signal is not cut off removes the noise of the output signal stored when the optical power signal is cut off. , An optical power vibration controller 15 for calculating a correction coefficient of an air flow rate to the burner 2 by comparing the signal with an optical spectrum signal of an optimum combustion state stored in advance, and a correction calculated by the optical power vibration controller 15. Based on coefficient Air flow regulator for adjusting the flow rate of air to the burner 2 had
It is configured with 11 and.

(Operation) With the above configuration, the flame 12 emitted by the burner 2 of the furnace 1
The optical power signal output by the optical power receiving section 13 by detecting the optical power of is blocked by the blocking section 20,
It is sent to the frequency analyzer 14. The frequency analyzer 14 analyzes the frequency of the optical power signal and outputs an optical spectrum signal. The optical power oscillation controller 15 removes the noise of the output signal stored when the optical power signal is cut off from the output signal when the optical power signal is not cut off, which is output from the frequency analyzer 14, and the signal and the optimum stored beforehand. The correction coefficient of the air flow rate to the burner 2 is calculated by comparing with the optical spectrum signal of the combustion state. The air flow controller 11 adjusts the flow rate of air to the burner 2 based on the correction coefficient calculated by the optical power vibration controller 15.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. In FIG. 1, reference numeral 1 is a furnace for heat-treating metal products and the like. A burner 2 is attached to the furnace 1, and a fuel supply pipe 3 and a combustion air supply pipe 4 are connected to the burner 2. The fuel supply pipe 3 is provided with a flow rate control valve 5 and a flow meter 6, and the combustion air supply pipe 4 is provided with a flow rate control valve 7. The fuel flow rate control valve 5 is controlled by a temperature controller 8. That is, a thermometer 9 is installed in the furnace 1, and the temperature controller 8 obtains a signal from the thermometer 9 and a signal from the flow meter 6 to determine the set temperature from the difference between the furnace temperature and the set temperature. The amount of combustion (fuel flow rate) required to obtain it is calculated and output. This output is given to the fuel flow rate control valve 5 and the combustion air flow rate control valve 7. Therefore, when the temperature in the furnace deviates from the set temperature, the flow rates of the fuel and the combustion air are adjusted so as to return to the set temperature.

The flow rate of the combustion air with respect to the flow rate of the fuel is calculated by the temperature controller 8 based on the fuel flow rate, but it is not desirable that the value be directly applied to the combustion air flow rate control valve 7. . For example, when the door (not shown) of the furnace 1 is opened and air enters the furnace 1, if the valve 7 is directly controlled by the output calculated based on the fuel flow rate, exhaust gas loss will increase. If the atomization state of the fuel deteriorates due to the abnormality of the burner 2, if left as it is, a large amount of soot will be generated due to poor combustion. In order to eliminate such an inconvenience, the output from the temperature controller 8 is corrected by the combustion air flow rate corrector 10 and then output to the flow rate control valve 7.

The combustion air flow rate compensator 10 constitutes a flow rate controller 11 for combustion air together with the temperature controller 8. The correction output for the combustion air flow rate corrector 10 is produced in the following combustion control device. That is, as shown in FIG. 1, the combustion control device sends to the optical power detector 16 an optical power receiver 13 for receiving optical power from the flame 12 formed by the burner 2 and a signal obtained by the optical power receiver 13. A light guide 18 for transmission, an optical power cutoff device 20 for cutting off the optical power periodically emitted from the flame in the middle of the light guide 18, and a frequency analyzer 14 for performing frequency analysis of the signal from the optical power detector 16. , A spectrum signal from the frequency analyzer 14 and a signal from the optical power cutoff device 20 are obtained to detect the combustion state and compare it with an optimal combustion state stored in advance. The power vibration controller 15 and the output from the optical power vibration controller 15 are used to adjust the flow rate of the combustion air supply pipe 4 to obtain the output for obtaining the flow rate of the combustion air necessary to eliminate the deviation. Go to valve 7 Comprising a Cormorant flow regulator 11.

The light receiving surface 17 of the optical power receiving portion 13 is installed at a position facing the flame in the furnace 1. The optical power cutoff device 20 provided in the middle of the light guide 18 is composed of a mechanism that periodically cuts off the optical power sent through the light guide 18 and a mechanism that checks whether the light power is currently cut off. ing. The optical power detector 16 is provided with a semiconductor photodetector for converting the optical power obtained through the optical guide into an electric signal, and outputs the intensity of light from the optical power receiver 13 as an optical power signal. Then, the optical power detector 16 sets the light from the optical power receiver 13 periodically to the “dark” state by the optical power cutoff device 20. The optical power signal as shown in FIG. 5 converted into an electric signal by the optical power detector 16 is amplified by the amplifier 19 as necessary.

The frequency analyzer 14 that receives the signal from the amplifier 19 is an FFT.
It is composed of an analyzer, a spectrum analyzer, etc., and the data which changes in time series as shown in FIG. 5 is converted into the power spectrum in the frequency domain as shown in FIG. The optical power vibration regulator 15 receives the power spectrum signal as shown in FIG. 6 and performs processing in the procedure shown in FIG. 2 to output it. This procedure will be described. First, in step 2-1, a power spectrum signal is input, and in the next step 2-2, it is judged whether or not the optical power is currently cut off by the signal from the optical power cutoff device 20, If it is cut off, the process proceeds to step 2-3, and the signal obtained by the noise from the outside of the device as shown in FIG. 16 or the noise generated inside the device is stored in the memory.

If it is determined in step 2-2 that the power has not been cut off, the process proceeds to step 2-4, where the power spectrum signal obtained from the signal obtained from the current flame is used to calculate the power stored in the memory in step 2-3. The spectrum component is removed and the power spectrum signal obtained from the true flame is obtained. Next, in step 2-5, the integral value A of all frequency bands of the power spectrum signal is calculated as shown in FIG. 3, and in step 2-6, the integral value B of the specific frequency band is calculated. Here, the specific frequency band is a frequency band in which the power spectrum changes most significantly due to changes in the combustion state.

Next, in step 2-7, the integrated value ratio B / (A-
B) = J is calculated. On the other hand, the integral value ratio K of the optimum combustion state for various fuel flow rates is obtained in advance, and the data is set in the optical power oscillation regulator 15, and the present integral value ratio J is set in step 2-8. The difference J−K = L,
In step 2-9, the combustion air flow rate correction coefficient M is calculated from the deviation L. The combustion air flow rate correction coefficient may be calculated by calculating an average value as shown in FIG. When the combustion air flow rate correction coefficient is calculated in this manner, the value of the optimum combustion state at that time naturally uses the value obtained by the average value ratio.

Combustion air flow rate correction coefficient M obtained as described above
From the optical power vibration regulator 15 to the combustion air flow rate compensator 10
Is output to The combustion air flow rate corrector 10 receives the reference air flow rate signal N from the temperature controller 8 in addition to the combustion air flow rate correction coefficient M. The reference air flow rate signal N is calculated by the temperature controller 8 based on the fuel flow rate signal. Then, the combustion air flow rate compensator 10 obtains the signals M and N, performs a correction calculation, outputs the result to the flow rate control valve 7, and adjusts its opening. In this way, the furnace 1 always operates in the optimum combustion state.

In the embodiment described above, the optical power cutoff device 20
Although the optical guide 18 is provided in the middle of the optical guide 18, the present invention is not limited to this, and may be provided inside the optical power receiving portion 13 and the optical power detecting portion 16 for implementation.

(Effects of the Invention) Since the present invention is the burner combustion control device configured as described above, even if the frequency range and the power spectrum range are different for each combustor, they are not affected and the power source noise is reduced. Stable combustion control can be performed without being affected.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a flow chart for explaining the operation of FIG. 1, and FIGS. 3 to 7 are for explaining the operation of FIG. 8 and 16 are graphs for explaining the operation of the conventional combustion control device. 1 …… Furnace 2 …… Burner 7 …… Flow control valve 11 …… Flow controller 12 …… Flame 13 …… Optical power receiver 14 …… Frequency analyzer 15 …… Optical power vibration controller

Claims (1)

[Claims] 1. An optical spectrum signal by analyzing the frequency of the optical power signal output by the optical power receiving section for detecting the optical power of the flame emitted by the burner of the furnace and outputting the optical power signal. A frequency analyzer that outputs a signal, a cutoff unit that is provided between the optical power receiving unit and the frequency analyzer and that periodically cuts off the optical power signal from the optical power receiving unit, and an optical power signal non- Noise of the output signal stored when the optical power signal is cut off is removed from the output signal at the time of cutoff, and the correction coefficient of the air flow rate to the burner is calculated by comparing the signal with the optical spectrum signal of the optimal combustion state stored in advance. A burner comprising: an optical power vibration controller; and an air flow rate controller that adjusts a flow rate of air to the burner based on a correction coefficient calculated by the optical power vibration controller. Combustion control device.