JP3127668B2 - Combustion control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control method applied to a combustor such as a boiler or an industrial furnace.

[0002]

2. Description of the Related Art For example, in a boiler as a combustor for supplying steam to a heating device in a factory, water is heated by a flame of a burner to produce steam. In such a system, since the steam pressure of the boiler fluctuates according to the amount of steam used in the heating device, it is necessary to operate the boiler so that the steam pressure is always constant. Therefore, conventionally, a fuel adjustment valve is provided in the middle of a fuel supply pipe that guides fuel to the burner, and an air adjustment valve is provided in the middle of an air supply pipe that guides air to the burner. In addition, the vapor pressure is detected by a pressure sensor, and the opening of the fuel regulating valve is adjusted by a control motor so that the vapor pressure becomes the same as a predetermined set value, and the amount of fuel supplied to the burner is increased or decreased. ing. In order to make the air supply follow the fuel supply, the fuel adjustment valve and the air adjustment valve are mechanically connected using a link mechanism or the like. Therefore, by operating one control motor, the opening adjustment of the fuel adjustment valve and the opening adjustment of the air adjustment valve are simultaneously performed.

However, in this technique, the opening of the fuel control valve is adjusted mainly so that the fuel supply amount is appropriate.
Since the opening of the air adjustment valve is adjusted accordingly, fine adjustment of the air supply amount cannot be performed. For this reason, in the above-mentioned technology, it is generally set in advance so that an appropriate amount or more of air is supplied in consideration of an unexpected situation such as a shortage of air.
Therefore, during normal operation of the boiler, an excessive amount of air is supplied to the burner, and heat loss increases. This phenomenon is
It is not preferable from the viewpoint of energy saving.

Therefore, in order to solve the above-mentioned problem, the adjustment of the opening of the fuel adjustment valve and the adjustment of the opening of the air adjustment valve are performed by separate control motors, and an optimum air supply amount for the fuel supply amount at that time is adjusted. It is conceivable to feedback-control the opening of the air regulating valve so that As one of them, there is a technique previously proposed by the present applicant (Japanese Unexamined Patent Publication No.
No. 94721).

In this technique, first, as shown in FIG. 23 (a), the state of the flame light is converted into an electric signal by an optical sensor, and the change over time of the electric signal is determined by the air ratio (the ratio of the air supply amount to the fuel supply amount). (Mixing ratio). FIG.
3 (b), the electric signal is subjected to frequency analysis,
The intensity of each frequency is obtained for each air ratio. This intensity is integrated over the entire frequency range, and the integrated value is used as the vibration power.

Since the following equation (1) may be established between the vibration power, the combustion amount, and the air ratio obtained in this manner, the air ratio control using this equation (1) is performed. Thus, efficient combustion with little heat loss is performed.

Λ = C × exp (p × f (x)) (1) In the above equation (1), λ is an air ratio, C is a constant, p is a vibration power, and f (x) is a combustion amount. Function.

[0008]

However, subsequent measurements have revealed that in many combustors, the vibration power exhibits an angle-shaped characteristic with respect to the air ratio. This is presumably because the vibration power is affected not only by the fluctuation (vibration component) due to the turbulence of the flame, but also by the emission intensity component of the flame or a component corresponding thereto.

For example, FIG. 24 shows the relationship between the air ratio and the luminous intensity component of the flame. FIGS. 28 (a) and 28 (b) show the temporal changes of the light emission intensity component and the vibration component. Further, FIGS. 25, 26, and 27 show the case where the set frequency at the time of frequency analysis is set to 20 Hz, 50 Hz, and 300 Hz.
The relationship between the air ratio and the vibration power is shown respectively.

According to FIGS. 24 and 25, when the set frequency is a low value (for example, 20 Hz) which is relatively insensitive to flame turbulence due to an increase or decrease in the amount of air, there is a strong relationship between the vibration power and the emission intensity component. There is a correlation, and it can be seen that the vibration power is strongly affected by the emission intensity component. Further, due to the influence of the flame turbulence, the vibration of the high frequency component tends to increase as the air ratio increases (FIG. 23B).
reference).

From these facts, when the set frequency is set to a relatively high value (for example, 300 Hz), as shown in FIG. 27, the higher the air ratio side, the higher the high frequency component increases, and the peak of the vibration power (maximum value). ) Shifts to the high air ratio side. Conversely, when the set frequency is set to a relatively low value (for example, 20 Hz), as shown in FIG. 25, the peak of the vibration power shifts to a lower air ratio side than in the case of 50 Hz (FIG. 26). Shows almost the same tendency.

FIG. 28 shows that such a phenomenon occurs.
This is because the amplitude of the vibration component changes in proportion to the change in the light emission intensity component, as shown in (a) and (b). For example, when it is considered that the furnace wall is formed of a heat insulating material, if the combustion of fuel and air is continued, the heat insulating material accumulates heat and the temperature in the furnace increases. Since the optical sensor detects infrared rays from the flame, when the temperature in the furnace increases as described above, the emission intensity component increases. In proportion to this, the amplitude of the vibration component increases.

That is, although the vibration component does not actually exhibit such a phenomenon, the electric signal from the optical sensor is affected by the light emission intensity component, and as a result, the amplitude of the vibration component increases. Would. Particularly, low-frequency components having large amplitudes are strongly affected by such influence. Therefore, if the set frequency at the time of the frequency analysis is lowered, the influence of the light emission intensity component is too strong than the influence of the vibration component, and the chevron characteristics of the light emission intensity component shown in FIG. Would.

[0014] With the above-mentioned chevron-shaped characteristics, the vibration power at one point exists for the air ratio at two points, and it is not possible to control the air ratio to an optimum value as it is. As described above, the above equation (1) holds only in a narrow range of the air ratio, and there is a problem that the combustor to which the related art can be applied is limited.

In order to solve the above problem, it is conceivable to increase the set frequency at the time of frequency analysis. That is, for example, as shown in FIG.
If the data is set at Hz, the vibration power corresponds to the air ratio almost one-to-one, and a positive correlation (primary characteristic) is observed between the two, so the combustion using the above equation (1) is performed. Control becomes possible. However, even in this case, the effect of the emission intensity component such as making the characteristic of the vibration power into a mountain shape remains to some extent. Therefore, depending on the type of the combustor and the fuel, even if data in a high frequency range (about several hundred Hz to several kHz) is obtained, the shape of a mountain shape may remain, and the above problem cannot be sufficiently solved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to make the influence of the luminous intensity component of the flame or the equivalent component on the vibration component constant, and to universally increase the air ratio. An object of the present invention is to provide a combustion control method capable of obtaining vibration power exhibiting primary characteristics.

[0017]

In order to achieve the above object, a first aspect of the present invention is to provide a fuel supply system comprising: a fuel supply pipe having an opening degree; And the amount of fuel and the amount of air supplied to the burner of the combustor via the fuel supply pipe and the air supply pipe are increased or decreased to change the state of the flame of the burner. The state is converted into an electric signal by an optical sensor, the amplitude of the electric signal is amplified, and then the frequency is analyzed.
Obtain the vibration power, which is the intensity integrated value in all frequency regions,
In the combustion control method in which the opening degree of the air regulating valve is adjusted so that the vibration power matches the optimum vibration power corresponding to the fuel flow rate at that time, the vibration component of the flame light is obtained from the electric signal from the optical sensor. and a component representative of the emission intensity of the flame was extracted respectively, in order to constant the effect on the vibration power by the emission intensity representative component of the same vibration power by dividing the vibration ingredient in the luminous intensity representative component I want to ask .

According to a second aspect of the present invention, in addition to the first aspect, before the amplitude of the electric signal is amplified, the vibration component is divided by a light emission intensity representative component. The signal is removed by a high-pass filter, and only a high-frequency component signal is extracted.

[0019] In the third invention, the first or the second one is used.
The light emission intensity component extracted separately from the vibration component from the electric signal by the optical sensor is used as the light emission intensity representative component of the invention of the invention.

[0020] In the fourth invention, the first or the second is used.
The representative amplitude component extracted from the amplitude of the vibration component of the electric signal by the optical sensor is used as the representative component of the light emission intensity of the invention.

[0021]

In the first aspect, the opening of the fuel control valve and the opening of the air control valve are adjusted. Then, the fuel flow rate and the air flow rate supplied to the burner of the combustor via the fuel supply pipe and the air supply pipe increase or decrease. Due to this increase or decrease, the state of the flame light of the burner changes.

The state of the flame light is converted into an electric signal using an optical sensor, and the frequency is analyzed after its amplitude is amplified to a predetermined level. After that, the vibration power, which is the intensity integrated value in the entire frequency range, is obtained. The opening of the air regulating valve is adjusted so that the vibration power matches the optimum vibration power according to the fuel flow at that time.

The amplitude of the oscillating component of the flame light changes in proportion to a change in a component representative of the luminous intensity of the flame (a luminous intensity representative component). That is, if the emission intensity representative component is small, the amplitude of the vibration component is apparently small, and if the emission intensity representative component is large, the amplitude of the vibration component is apparently large.
Therefore, if this electric signal is used as it is for subsequent processing, in a combustor in which the influence of the emission intensity representative component becomes more dominant than the oscillation component, the vibration power is strongly affected by the emission intensity representative component, Vibration power showing primary characteristics with respect to the air ratio cannot be obtained.

[0024] However, in the first invention, the vibration component and emission intensity representative component from the electrical signal by the optical sensor are extracted respectively, then the vibration Ingredient is divided by the emission intensity representative component. By this division, the influence of the emission intensity representative component on the amplitude of the vibration component is made constant. For this reason, the vibration power is not affected by the emission intensity representative component, and the characteristic of the vibration power shows a primary characteristic with respect to the air ratio. Therefore,
If was seeking et vibration power as described above the same as the optimum vibration power, it is possible to obtain an optimum air ratio.

The electric signal obtained by the division is a signal obtained by combining various basic waveforms having different frequencies and amplitudes, and the magnitude of the amplitude of each basic waveform is inversely proportional to the frequency. For this reason, when the amplitude of the electric signal after the division is amplified, if the signal of the low frequency component is included in the electric signal, the amplitude of this signal is larger than the amplitude of the signal of the high frequency component. Therefore, amplification is performed based on the signal of the same low frequency component. Then, the amplitude of the high frequency component signal is not amplified to a sufficient magnitude.

On the other hand, in the second invention, the low-frequency component signal of the divided electric signal is removed by the high-pass filter, and only the high-frequency component signal is extracted and amplified. At the time of this amplification, the amplitude of the signal of the high frequency component is used as a reference, so that the amplitude of the signal of the high frequency component is sufficiently large.

Therefore, after the amplitude amplification, the signal of the high frequency component whose amplitude has been amplified to a sufficient level is subjected to frequency analysis, so that a power spectrum including the high frequency component is obtained. Accordingly, vibration power showing a primary characteristic with respect to the air ratio is obtained.

Here, when the optical sensor used in the first or second invention is composed of an infrared element, the optical sensor has a characteristic that it is easily affected by radiation from a high-temperature substance other than a flame. That is, even if the combustion conditions such as the fuel amount and the air amount are constant, when the influence of radiation other than the flame is large, only the emission intensity representative component increases greatly compared to the case where the influence is small, and the vibration component Hardly changes its amplitude. That is, it is difficult to establish the assumption that the amplitude of the vibration component changes in proportion to the change of the light emission intensity representative component.

Therefore, for example, in a combustor such as a boiler in which the temperature in the furnace does not become too high, the optical sensor is not much affected by the radiation, and there is no particular problem. However, in a combustor such as an industrial furnace where the temperature inside the furnace becomes high, radiation from a high-temperature substance such as a refractory material or a work cannot be ignored, and the optical sensor simultaneously detects radiation energy in addition to the state of the flame. As a result, the vibration power that should represent the combustion state actually represents a state that includes disturbance other than combustion,
This cannot be used as a control index.

From this point of view, in the third aspect, a light emission intensity component extracted separately from a vibration component of an electric signal by the optical sensor is used as a light emission intensity representative component.
In the fourth aspect, a representative amplitude value extracted from the amplitude of the vibration component of the electric signal by the optical sensor is used as a representative light emission intensity component.

For this reason, when the third invention is applied to a combustor such as a boiler with low radiation, the luminous intensity component used as the luminous intensity component hardly contains the influence of radiation. Therefore, when the vibration component is divided by the light emission intensity component, the influence of the light emission intensity component on the vibration component becomes constant.

On the other hand, when the fourth invention is applied to a combustor such as an industrial furnace having a high-temperature substance other than a flame, a representative amplitude value extracted from the amplitude of the vibration component is used as a representative emission intensity component. Here, when the temperature of the flame itself rises, the vibration component increases in proportion to the increase of the luminescence intensity component, and when there is radiation from a high-temperature substance other than the flame, the luminescence intensity component Although the amplitude increases, the amplitude of the vibration component does not change, indicating that the amplitude representative value is hardly affected by radiation.

Therefore, even when the optical sensor detects the energy of the radiation, the vibration component is divided by the representative amplitude value excluding the influence of the radiation. As a result, the influence of the amplitude representative value corresponding to the emission intensity on the vibration component becomes constant.

[0034]

【Example】

(First Embodiment) A first embodiment in which the combustion control methods of the first and third inventions are applied to a boiler for supplying steam to a heating device in a factory will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of an entire combustion facility including a boiler as a combustor, and FIG. 2 shows an enlarged cross section along the line AA in FIG. The main body 2 of the boiler 1 has a horizontally long, substantially cylindrical shape. The inside of the main body 2 is partitioned by a furnace wall 15 into a combustion chamber 3 and a liquid chamber 4 surrounding the combustion chamber 3.

A burner 5 for emitting a flame F toward the inside of the combustion chamber 3 is attached to a side wall of the main body 2. A fuel pump 7 and a fuel tank 8 are connected to the burner 5 via a fuel supply pipe 6. By operating the fuel pump 7, the fuel in the fuel tank 8 is supplied to the burner 5 through the fuel supply pipe 6. Further, a blower fan 11 is provided on the burner 5 via an air supply pipe 9.
By the operation of 1, air is supplied to the burner 5 through the air supply pipe 9. Accordingly, the burner 5 is supplied with an air flow generated by the blower fan 11 in addition to the fuel. These fuel and air are mixed and burned by the burner 5, and a flame F is generated. The light of the flame F has a vibration component and a light emission intensity component.

A liquid 12 such as water is stored in the liquid chamber 4 with a small space S left above. As shown in FIG. 2, a smoke tube 13 is disposed in the liquid chamber 4, and the exhaust gas generated in the combustion chamber 3
3 and is discharged outside through a chimney 14 protruding from the combustion chamber 3. A heating device is connected to the space S via a pipe (not shown).

Therefore, to the liquid 12 in the liquid chamber 4, the heat of the flame F of the burner 5 is transmitted through the furnace wall 15, and the heat of the exhaust gas passing through the smoke tube 13 is transmitted through the smoke tube 13.
The transfer of these heats heats the liquid 12 to vapor, and the vapor is led to the heating device through the pipe. Here, since a liquid having a large specific heat, such as water, is in contact with the furnace wall 15, the temperature of the furnace wall 15 rises only to about 200 to 300 ° C. And since the steam pressure in the liquid chamber 4 fluctuates according to the amount of steam consumed in the heating device,
In this embodiment, the vapor pressure in the liquid chamber 4 is kept constant.
The fuel flow is increased or decreased.

In order to adjust the amount of fuel supplied to the burner 5, a fuel regulating valve 16 is interposed in the fuel supply pipe 6. A control motor 18 for opening adjustment is connected to the fuel adjustment valve 16 via a link mechanism 17. An air regulating valve 19 is interposed in the air supply pipe 9 in order to regulate the amount of air supplied to the burner 5. A control motor 22 for adjusting the opening is connected to the air adjustment valve 19 via a link mechanism 21.
The control motors 18 and 22 are motors that can rotate their own drive shafts by an angle corresponding to the input signal.

A pressure gauge 23 is provided at an upper portion of the main body 2 to detect an operation state of the boiler 1. The pressure gauge 23 detects the pressure of steam generated as the liquid 12 is heated. A flow meter 24 is interposed in the middle of the fuel supply pipe 6. The flow meter 24 measures the flow rate of the fuel flowing through the fuel supply pipe 6. Further, in the main body 2 of the boiler 1, a viewing window 25 is provided on a side wall facing the burner 5. A sensor amplifier 27 is connected to the viewing window 25 via an optical fiber 26.

The sensor amplifier 27 has a built-in optical sensor 28 composed of an infrared detecting element such as a germanium photodiode or a phototransistor. The optical sensor 28 takes in the flame light passing through the viewing window 25 and the optical fiber 26 and converts it into an electric signal. That is, the optical sensor 28
, An electromotive current having a magnitude proportional to the brightness of the flame F flows. As shown in FIG. 3, the sensor amplifier 27 includes a current / voltage converter 29, a DC / AC converter 31, and an integrator 3
2. Built-in analog divider 33 and amplifier 34. The sensor amplifier 27 sequentially processes the electric signal from the optical sensor 28 using these converters and the like.

As shown in FIG. 1, the pressure gauge 23 is connected to an input side of a pressure regulator 35. Pressure regulator 35
The control motor 18 is connected to the output side. When the pressure regulator 35 receives the steam pressure signal detected by the pressure gauge 23, it outputs a drive signal to the control motor 18 to adjust the opening of the fuel regulating valve 16. The fuel supply amount to the burner 5 is adjusted by the opening degree adjustment, and the vapor pressure in the liquid chamber 4 is controlled so as to become a preset pressure. As a result, the supply of steam to the heating device is performed stably.

The flow meter 24 and the sensor amplifier 27 are
The allowable input voltage is connected to the input side of the combustion control device 36 set to a predetermined range (for example, ± 2.5 V). The control motor 22 is connected to the output side of the combustion control device 36. Upon receiving the analog signal from the sensor amplifier 27 and the fuel flow rate signal from the flow meter 24, the combustion control device 36 performs a predetermined calculation based on both signals, and performs control motor 2 control based on the calculation result.
2 to control the opening of the air regulating valve 19.

The combustion control device 36 includes a control panel 3
7 are connected so that signals can be exchanged between the two. For example, when some trouble occurs in the operation of the boiler 1, a command signal for forcibly stopping the operation of the boiler 1 is output from the combustion control device 36 to the control panel 37.

Next, the contents of processing executed in the sensor amplifier 27 will be described with reference to FIG. First, the sensor amplifier 27 captures the flame light of the burner 5 into the optical sensor 28 through the viewing window 25 and the optical fiber 26, and converts the flame light into an electric signal (current). The amplitude of the vibration component in the electric signal changes in proportion to the change in the emission intensity component of the flame light. In other words, when the emission intensity component of the flame light is small, the amplitude of the vibration component is apparently small, and when the emission intensity component is large, the amplitude of the vibration component is apparently large.

Next, the sensor amplifier 27 converts the electric signal into a voltage signal as shown in FIG. The waveform of this signal oscillates with the passage of time around a predetermined DC voltage. In the signal waveform, the average value of the DC voltage represents the emission intensity component, and the vibration component represents the fluctuation of the flame F.

Next, in the DC / AC converter 31, the sensor amplifier 27 removes the light emission intensity component from the signal waveform of FIG. 5A and converts only the vibration component into an AC voltage signal.
In this way, a vibration component is extracted from the electric signal from the optical sensor 28 (see FIG. 5B). In the integrator 32, the sensor amplifier 27 integrates the signal waveform of FIG. The time constant of the integrator 32 can be set arbitrarily, and is adjusted as necessary. By this processing, the vibration component in the signal waveform is smoothed, and an average light emission intensity component is obtained. In this way, the light emission intensity component is extracted from the electric signal from the optical sensor 28 (FIG. 5C).
reference). In this embodiment, the light emission intensity component itself is used as a light emission intensity representative component, and is used for the subsequent arithmetic processing.

Here, the signal from the current / voltage converter 29 is integrated and smoothed by the integrator 32 in the analog divider 33 in the subsequent stage, for example, the signal (vibration component) from the DC / AC converter 31. Is divided by the signal from the current / voltage converter 29 instead of the signal from the integrator 32, the following problem occurs. That is, the signal (vibration component) from the DC / AC converter 31 changes over time. Further, the signal from the current / voltage converter 29 also changes over time. For this reason, when the former signal is divided by the latter signal, although division in the low frequency range is not particularly problematic, as a result of division in the high frequency range, the output waveform is distorted and the error increases.

As described above, since the amplitude of the vibration component in the electric signal from the optical sensor 28 changes in proportion to the change in the emission intensity component of the flame light, the sensor amplifier 27 extracts In the analog divider 33, the vibration component is divided by the emission intensity component. By this division, an electric signal in which the influence of the emission intensity component is constant is obtained. This electric signal is constituted only by a component caused by the disturbance of the flame F.

Therefore, as shown in FIG. 6, even if two different waveforms a and b are obtained after the current / voltage conversion, the effect of the disturbance of the flame F is the same, and the emission intensity is not changed. If the components are different, an electric signal having substantially the same waveform can be obtained by performing the extraction processing and the division processing. More specifically, in the case of the waveform a having a large amplitude, the voltage of the average value (emission intensity component) increases, so that the amplitude of the electric signal obtained as a result of the division processing decreases. In contrast,
In the case of the waveform b having a small amplitude, the voltage of the average value (emission intensity component) becomes low, so that the amplitude of the second electric signal obtained as a result of the division processing becomes as small as above. As described above, in the present embodiment, the amplitude of the vibration component increased or decreased due to the influence of the light emission intensity component is made constant by dividing the vibration component by the light emission intensity component.

The electric signal obtained as described above includes a signal of a low frequency component having a predetermined amplitude and a signal of a high frequency component contained in the signal and having an amplitude smaller than that of the signal of the low frequency component. Signal.

Then, the sensor amplifier 27 amplifies the amplitude of the signal after the division to a predetermined level by the amplifier 34, and then outputs the amplified signal to the combustion control device 36. Next, the processing executed by the combustion control device 36 will be described with reference to FIG.

In the figure, the portion surrounded by the dashed line is the main control content. Here, the vibration power of the flame F is obtained based on the analog signal output from the sensor amplifier 27, and the vibration power at the optimum air ratio according to the fuel flow rate by the flow meter 24 is obtained. Then, the opening of the air regulating valve 19 is adjusted so that the former vibration power matches the latter vibration power.

More specifically, when the combustion controller 36 receives the analog signal from the sensor amplifier 27, the A / D converter 38 converts the analog signal into a digital signal. After the A / D conversion, the DSP (digital signal processor) 39 of the combustion control device 36
Performs FFT (Fast Fourier Transform) on the digital signal. In addition, in the combustion control device 36 of the present embodiment, the A / D
A converter having a resolution of 12 bits is used as the converter 38. In the combustion control device 36, the FFT
The upper limit of the measurement frequency range during processing can be set up to 500 Hz.

The FFT process is a process for obtaining the intensity of each frequency component in the digital signal (FIG. 23).
(B)). By the FFT processing, the digital signal is subjected to frequency analysis to obtain an intensity waveform (power spectrum) of each frequency component. The area of this waveform indicates the fluctuation state and brightness of the flame. Since there is a strong correlation between the area of the power spectrum waveform and the combustion state, the combustion state can be quantified by calculating the area. From this,
The combustion control device 36 integrates the intensity waveform of each frequency component in the entire frequency region by the FFT processing unit 41, and obtains the area (vibration power) of the intensity waveform.

Here, the influence of the emission intensity component on the amplitude of the vibration component is made constant from the electric signal used for calculating the vibration power by the division process in the sensor amplifier 27. For this reason, the vibration power is not affected by the emission intensity component, and has a substantially primary characteristic with respect to the air ratio. 7 and 8 show the relationship between the air ratio and the vibration power when the set frequencies in the frequency analysis are 200 Hz and 300 Hz, respectively. As is clear from both figures, there is a positive correlation (primary characteristic) between the vibration power and the air ratio. This means that as you increase the air ratio,
This can be supported by the phenomenon that the amount of air supplied to the burner 5 increases, the flow velocity of the air increases, and flicker (turbulence of the flame F) increases. Therefore, accurate air ratio control can be performed by using this vibration power.

Next, as shown in FIG.
Reference numeral 6 denotes a moving average processing unit 42 for averaging the vibration power obtained by the FFT processing unit 41 by the average number set in the moving average number table 43. This processing is FF
This is a process for reducing variation between data obtained by the T process.

On the other hand, when the combustion control device 36 captures the fuel flow rate signal from the flow meter 24, the moving average processing section 44 averages the fuel flow rate signal by the average number set in the moving average number table 45. Then, the combustion control device 36 reads the vibration power according to the fuel flow rate subjected to the averaging process with reference to the broken line table 46. A target value for the fuel flow rate is set in the broken line table 46 in advance. The target value here is the value of the vibration power at the time of the minimum air amount that does not generate smoke.

The combustion control device 36 is connected to the folding line table 4.
The adder 47 adds the target value of the vibration power read from 6 and the vibration power processed by the moving average processing unit 42. In this case, the difference between the two is obtained by subtracting the vibration power from the target value.

Subsequently, the combustion control unit 36 performs a dead zone process on the deviation signal from the adder 47 in the dead zone processing unit 48. That is, a dead zone is set in the dead zone processing section 48 in advance, and if the deviation fluctuates within the dead zone, it is not regarded as a fluctuation. Then, the combustion control device 36 performs a PID operation on the deviation after the dead zone processing in the PID operation unit 49, and outputs a signal for driving and controlling the control motor 22 to the adder 51 so as to eliminate the deviation at that time. .

Then, the combustion control device 36 limits the signal passing through the adder 51 in the output limiter 52. That is, an upper limit value and a lower limit value are set in the output limiter 52, and when the signal passing through the adder 51 exceeds the upper limit value and falls below the lower limit value, the upper limit value is forcibly set. And the lower limit. The signal that has passed through the output limiter 52 is output to the control motor 22, and the opening of the air adjustment valve 19 is adjusted by driving the signal.

In the combustion control device 36, in addition to the above-described control, correction is performed for the purpose of improving the followability to changes in the combustion state and optimizing the air ratio under a partial load.

To explain the correction, the combustion control unit 36 detects whether the average value of the vibration power by the moving average processing unit 42 has fallen below a preset lower limit value by the PV lower limit monitor 53. That is, for example, if a value corresponding to −10% of the target value of the vibration power at that time is set in the broken line table 46 and the average value of the vibration power falls below the set value for some reason, P
The V lower limit monitor 53 detects the state.

Here, when the PV lower limit monitor 53 detects that the average value of the vibration power has fallen below the set value, the combustion controller 36 performs a ratio operation in the PV lower limit ratio calculator 54. PV lower limit monitor ratio calculation unit 54
, A predetermined ratio (for example, 10%) is set in advance, and the combustion control device 36 outputs the set ratio to the adder 51 via the comparison and selection unit 55. Then, in the adder 51, the set ratio is added to the output signal of the PID calculation section 49, and the air regulating valve 19 is forcibly opened. Such processing is performed by the moving average processing unit 42.
When the average value of the vibration power at the time is lower than the value set by the PV lower limit monitor 53, the air amount is absolutely insufficient, and it is necessary to open the air regulating valve 19 suddenly to supplement the air. It is.

On the other hand, the combustion control device 36 controls the change rate monitor 5
6, the degree of change in the fuel flow rate is detected. Specifically, a predetermined change rate (for example, 5%) is preset in the change rate monitor 56, and it is detected whether or not the fuel flow rate suddenly increases and the change rate exceeds the predetermined change rate.

When the change rate monitor 56 detects that the change rate of the fuel flow rate is equal to or more than the predetermined rate, the combustion control device 36 performs a ratio calculation in the fuel change rate monitor ratio calculating section 57. A predetermined ratio (%) is set in the fuel change rate monitor ratio calculation unit 57 in advance.
Outputs the set ratio to the adder 51 via the comparison and selection unit 55. Then, in the adder 51, the set ratio is added to the output signal of the PID calculator 49,
The air regulating valve 19 is forcibly opened. Such processing is performed in order to follow a rapid change in the fuel flow rate.
This is because it is necessary to momentarily open the air regulating valve 19 to supplement the air.

That is, if the follow-up property is poor when increasing the amount of air in accordance with the increase in fuel, the required amount of air cannot be obtained, causing black smoke and misfire. For this reason, the rate of change of the average value of the output signal from the flow meter 24 is constantly monitored by the rate-of-change monitor 56 to grasp the fuel flow rate. The degree information is added and output.

When the PV lower limit monitor ratio calculator 54 and the fuel change rate monitor ratio calculator 57 operate simultaneously, the comparison / selection unit 55 determines which signal has priority. is there. In the present embodiment, the comparing and selecting section 55 selects a value having a larger absolute value.

As described above, in order to prevent shortage of the air amount, more air than the appropriate amount is supplied to the burner 5, and when the fuel flow rate increases, the air flow rate is increased. ing.

As described above, since the amplitude of the vibration component of the electric signal by the optical sensor 28 changes in proportion to the emission intensity component, in this embodiment, the analog divider 33 is used in the state of the analog signal before the FFT processing. , The vibration component is divided by the light emission intensity component, and the signal from which the influence of the light emission intensity component is removed is subjected to FFT processing to obtain the vibration power.
During the above process, by making the effect of the luminescence intensity component constant,
Only the influence of the component caused by the turbulence of the flame F is extracted. For this reason, the power spectrum shape at the time of optimal combustion is almost the same regardless of combustion. That is, the vibration powers in the optimum combustion state become substantially equal. As a result, it is possible to obtain a vibration power that shows a substantially primary characteristic with respect to the air ratio without increasing the set frequency in the frequency analysis. Accordingly, unlike the related art in which the applicable boiler 1 is limited, in this embodiment, more accurate and efficient air ratio control can be realized in many boilers. (Second Embodiment) Next, a second embodiment in which the combustion control methods of the first and fourth inventions are applied to an industrial furnace such as a heat treatment furnace will be described with reference to FIGS. This industrial furnace is a combustor for heat-treating the work. Here, the heat treatment refers to, for example, carburizing and quenching of steel parts, firing of ceramics, and dissolution of aluminum, pig iron, and the like.

FIG. 9 is a view corresponding to FIG. 1 in the first embodiment, and shows a schematic configuration of the entire combustion equipment including an industrial furnace 61 as a combustor. The furnace 62 of the industrial furnace 61 has a horizontally long rectangular box shape, and on its inner surface, a refractory material 63 made of a refractory brick or the like is stuck instead of the liquid 12 such as water in the first embodiment. I have. For this reason, the refractory material 63 accumulates heat by the flame F emitted from the burner 5, and has a higher temperature (about 900 to 10) than the furnace wall 15 of the boiler 1 in the first embodiment.
00 ° C).

A transfer device (not shown) is provided in the furnace 62. By the operation of the transfer device, the work 64 is transferred in the furnace 62 in a direction orthogonal to the paper surface, and a heat treatment is performed in the transfer process. Also, the pressure gauge 23 in the first embodiment is used.
Instead, the furnace 62 is provided with a temperature sensor 65 for detecting the internal temperature. This temperature sensor 6
5 and the control motor 18 are connected to a temperature controller 69. The temperature controller 69 is connected to the temperature sensor 65.
When the temperature signal detected by the above is input, a drive signal is output to the control motor 18 to adjust the opening of the fuel adjustment valve 16. The fuel supply amount to the burner 5 is adjusted by this opening degree adjustment, and the temperature inside the furnace 62 is controlled to be a preset temperature.

With respect to the configuration on the combustion equipment, the configuration other than the above is the same as that of the first embodiment. Therefore, the same members as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the boiler 1 is connected to the industrial furnace 61 as described above.
Accordingly, the processing executed in the sensor amplifier 27 is changed. This is to cope with the characteristic that the optical sensor 28 including the infrared detecting element is easily affected by radiation from a high-temperature substance other than the flame F.

FIGS. 12A and 12B show the optical sensor 28.
5 shows a signal waveform after current / voltage conversion of the detection signal of FIG.
FIG. 12A shows a case where there is no influence of radiation.
(B) is a case where the influence of radiation is large. From these figures, it can be seen that even when the combustion conditions such as the fuel amount and the air amount are constant, when the effect of radiation from other than the flame F is large, only the emission intensity component increases significantly compared to the case without the effect. It can be seen that the amplitude of the vibration component hardly changes. That is, it is difficult to assume that the amplitude of the vibration component changes in proportion to the change in the emission intensity component.

Therefore, in the case where the furnace wall 15 is a water-cooled wall and the temperature in the combustion chamber 3 is relatively low as in the boiler 1 in the first embodiment, the optical sensor 28 is not easily affected by radiation. No problem. However, in the industrial furnace 61 in which the temperature inside the furnace 62 becomes high, radiation from high-temperature substances such as the refractory material 63 and the work 64 cannot be ignored, and the optical sensor 28 simultaneously detects radiation energy in addition to the state of the flame F. I will.
As a result, the vibration power that should represent the combustion state actually represents a state that includes disturbance other than combustion, and cannot be used as a control index.

FIG. 13 (a) shows the result of dividing the vibration component by the emission intensity component and performing FFT processing to obtain the intensity waveform (power spectrum) of each frequency component for each air ratio. From this figure, it can be seen that the power spectrum deviation between the air ratios is relatively large in the low frequency range B, while the power spectrum deviation between the air ratios is small in the other frequency ranges. This indicates that when the air ratio changes, the temperature of the flame changes, and the apparent amplitude of the vibration component increases or decreases.

FIG. 14A shows the vibration from the start of the furnace when a metal piece (corresponding to the work 64) is heated in an industrial furnace 61 under a constant combustion condition. It shows the power change over time. This vibration power is based on the electric signal obtained by dividing the vibration component by the emission intensity component, as described in the first embodiment. From this figure, it can be seen that even when the combustion conditions are constant, the vibration power is reduced with time due to the effect of the increase in the emission intensity component. For this reason, when the furnace wall temperature or the like greatly changes from the time of furnace startup to the time of steady operation, it is difficult to perform appropriate air ratio control using vibration power.

In view of such circumstances, in the present embodiment, the amplitude of the vibration component is corrected to be constant by a method that is not affected by radiation without using the light emission intensity component. This method is characterized in that when the temperature of the flame F itself rises, the vibration component increases in proportion to the increase of the luminous intensity component, and when there is radiation from the refractory material 63 or the work 64, the luminous intensity increases. This is devised in that the component increases but the amplitude of the vibration component hardly changes. Specifically, a value representative of the amplitude of the vibration component that is not affected by radiation is taken, and this value is set as a substitute value (light emission intensity representative component) for the light emission intensity component.

FIG. 10 is a functional block diagram corresponding to FIG. 3 in the first embodiment. The sensor amplifier 27 is an optical sensor 2
8, current / voltage converter 29, DC / AC converter 31, amplifier 66, rectifier 67, integrator 68, analog divider 3
3 and an amplifier 34. Sensor amplifier 27
, Sequentially processes the electrical signals detected by the optical sensor 28 by using these converters and the like. More specifically, the sensor amplifier 27 captures the flame light of the burner 5 into the optical sensor 28 through the viewing window 25 and the optical fiber 26, converts the flame light into an electric signal (current), and converts the signal into a current / voltage signal. The converter 29 converts the signal into a voltage signal as shown in FIG. The waveform of this signal oscillates with the passage of time around a predetermined DC voltage. Next, the sensor amplifier 27 is connected to the DC / AC converter 31 in FIG.
Is converted into an AC voltage signal only from the waveform (1), and the amplitude of this signal is amplified by the amplifier 66. In this way,
A vibration component as shown in FIG. 11B is extracted from the electric signal from the optical sensor 28.

In the rectifier 67, the sensor amplifier 27 rectifies the signal waveform shown in FIG. By this processing, an AC voltage signal is converted into a DC voltage signal as shown in FIG. Subsequently, in the integrator 68, the signal waveform of FIG. The integration time for this process is set according to the combustion equipment. That is, if the integration time is set to be long, the response when the combustion state changes may be deteriorated. Therefore, the time is set to a time in consideration of the followability, for example, about 1 second. The rectified DC voltage signal is subjected to integration processing as shown in FIG.
The smoothing is performed as shown in FIG. The smoothed signal is a value representative of the amplitude of the vibration component, and corresponds to a component representative of the emission intensity (emission intensity representative component). This signal is
Since it is obtained based on a vibration signal which is not affected by the radiation, it takes substantially the same value even if there is radiation unless the state of the flame F changes.

After the smoothing, the sensor amplifier 27 converts the vibration component of FIG.
Divide by the representative amplitude value of (d). By this division, an electric signal in which the influence of the representative amplitude value (representative emission intensity component) is constant is obtained. This signal eliminates the effects of radiation,
This is a signal based only on the change of the flame F.

Then, the sensor amplifier 27 amplifies the amplitude of the signal after the division to a predetermined level by the amplifier 34, and then outputs the amplified signal to the combustion control device 36. The processing executed by the combustion control device 36 is the same as that of the first embodiment. Here, the intensity waveform (power spectrum) of each frequency component obtained by the FFT processing is shown in FIG.
(B). From this figure, it can be seen that the power spectrum is almost constant in the low frequency range regardless of the air ratio. This means that the influence of the brightness of the flame F is fixed by dividing the vibration component by the amplitude representative value as the emission intensity representative component, and the basic amplitude of the vibration component is corrected to be substantially constant. Is shown. Also, it can be seen from the figure that the power spectrum appears up to a higher frequency range as the air ratio increases. This indicates that as the amount of air increases, the flicker of the flame F in the high frequency range increases.

FIG. 15 shows the relationship between the air ratio and the vibration power. From this figure, it can be seen that the vibration power has a substantially primary characteristic with respect to the air ratio. further,
FIG. 13B shows the time change of the vibration power measured under the same conditions as in FIG. 13A. From both figures, in the former, the vibration power decreases with time, whereas in the latter, the vibration power has a substantially constant value regardless of time. For this reason, the latter vibration power can be used as an air-fuel ratio control index without any problem.

As described above, in this embodiment, the vibration component is divided by the representative amplitude value obtained from the vibration component without using the light emission intensity component in the first embodiment. For this reason,
Even when applied to various types of combustors, the amplitude of the vibration component that changes as the combustion state changes can be reliably kept constant, and the vibration power that always corresponds to the air ratio on a one-to-one basis can be obtained. (Third Embodiment) Next, a third embodiment embodying the first and second inventions will be described with reference to FIGS. In the third embodiment, as shown in FIG. 16, a high-pass filter 71 is interposed between the analog divider 33 and the amplifier 34 in the sensor amplifier 27. The other configuration is the first
This is the same as the embodiment.

The reason why the high-pass filter 71 is added in this way is that the measurement is performed using a dedicated FFT analyzer separately from the combustion control device 36. It has been found that sometimes does not show the primary characteristics of the air ratio. For example, if the upper limit of the measurement frequency range at the time of the FFT processing is 50 Hz or less, the vibration power may be more affected by the change in the combustion state than the change in the turbulence due to the air ratio. Then, as shown in FIG. 19, the correlation between the vibration power and the air ratio becomes weak. Further, depending on the combustor, the effect of the luminescence intensity component on the air ratio may not be constant. Then, it is difficult for the vibration power to have a primary characteristic with respect to the air ratio.

In order to make the vibration power the primary characteristic of the air ratio, it is necessary to set the upper limit of the measurement frequency range at the time of FFT processing to be high (for example, 200 Hz or more). In this manner, regardless of the type and type of the combustor, vibration power having a primary characteristic with respect to the air ratio can be obtained.

On the other hand, the combustion control device 36 used in the first embodiment can set the upper limit of the measurement frequency range at the time of FFT processing to 500 Hz. Therefore, from this point, the above requirement (the upper limit of the measurement frequency range is set to 200
Hz or more). However, in the sensor amplifier 27, the electric signal converted into current / voltage after being converted by the optical sensor 28 is a composite signal of various basic waveforms having different frequencies and amplitudes. Is inversely proportional to Therefore, when the signal is amplified by the amplifier 34 in the sensor amplifier 27, the maximum amplitude of the electric signal is determined by the allowable input voltage (this value) with reference to a low-frequency signal having a large amplitude as shown in FIG. In this case, the amplification factor is adjusted to fall within ± 2.5 V). For this reason, the high-frequency signal in the amplified electric signal has an amplitude relatively smaller than that of the low-frequency signal, and the A / D converter 3 having a small resolution.
8 may not be recognized. In this case, even if the FFT processing is performed, only a power spectrum of a frequency component up to about 80 Hz is obtained as shown in FIG. 18A, and vibration power having a primary characteristic with respect to the air ratio cannot be obtained.

To obtain a power spectrum including a frequency component up to about 500 Hz, the resolution of the A / D converter 38 is increased, or the DSP 39 is changed to one capable of performing a more accurate calculation. However, the combustion control device 36 itself becomes very expensive.

From this point of view, the present embodiment adds a high-pass filter 71 to the sensor amplifier 27 and
Prior to the amplitude amplification in step 4, the signal of the low frequency component in the electric signal is removed by the high-pass filter 71.

FIG. 16 is a functional block diagram showing the contents of processing executed in the sensor amplifier 27, and corresponds to FIG. 3 in the first embodiment. When the analog divider 33 divides the vibration component by the emission intensity component, the sensor amplifier 27 removes the low-frequency component signal from the resulting electric signal with the high-pass filter 71 and extracts only the high-frequency component signal. The cutoff frequency of the high-pass filter 71 can be set arbitrarily, and is preferably set according to the target boiler 1. The cutoff frequency is
Usually, it is set to about 20 Hz.

Subsequently, the sensor amplifier 27 amplifies the signal of the high frequency component to a predetermined level by the amplifier 34.
At the time of this amplification, only the signal of the high frequency component is extracted as described above, so that the amplitude of this signal is used as a reference, and the amplitude is amplified to a sufficient magnitude. Thereafter, the sensor amplifier 27 outputs the amplified analog signal to the combustion control device 36.

Since the contents of the processing executed by the combustion control device 36 are the same as those of the first embodiment,
Here, detailed description is omitted. However, due to the processing in the sensor amplifier 27, the influence of the emission intensity component on the amplitude of the vibration component is made constant from the electric signal input to the combustion control device 36. In addition, the amplitude of the high frequency component signal is amplified to a sufficient level. Therefore, the power spectrum of FIG. 18B obtained by the FFT processing has a waveform as if the low frequency components in the power spectrum of FIG. 18A were removed. By this removal, the frequency at which the power spectrum becomes maximum becomes higher than in the first embodiment. As a result, a power spectrum containing higher frequency components (about 300 Hz) than in the first embodiment can be obtained.

The combustion control device 36 determines the vibration power based on the power spectrum. The vibration power is not affected by the emission intensity component and is determined from the power spectrum including the high frequency component. For this reason, the vibration power has a substantially primary characteristic with respect to the air ratio.

FIG. 20 shows the relationship between the air ratio and the luminescence intensity component when the A-fuel oil-fired furnace tube boiler whose evaporation amount is 5 tons / hour is operated at a combustion amount of 360 liters / hour. Using this light emission intensity component, after performing various arithmetic processing (division and amplification) in the sensor amplifier 27 of the first embodiment (omitting the high-pass filter 71), the output signal was subjected to FFT processing by a dedicated FFT analyzer. Measurement frequency range is 0-2
00 Hz. FIG. 21A shows the relationship between the vibration power and the air ratio obtained by the FFT processing. From this figure, it can be seen that there is a strong positive correlation (primary characteristic) between the vibration power and the air ratio.

Further, using the emission intensity component shown in FIG.
After performing various arithmetic processing in the sensor amplifier 27 of the present embodiment (using the high-pass filter 71), the output signal was subjected to FFT processing by the combustion control device 36 of the present embodiment. The measurement frequency range is 30 to 400 Hz. FIG. 21B shows the relationship between the vibration power and the air ratio obtained by the FFT processing. 21 (a) and 21 (b), there is almost no change in the correlation between the air ratio and the vibration power even if there is no low frequency component, and the air ratio is controlled without any problem by the combustion control method of this embodiment. We can see that we can do it.

As described above, according to the present embodiment, a power spectrum including a high frequency component can be obtained by a simple modification of adding the high-pass filter 71, and vibration power having a primary characteristic with respect to the air ratio can be obtained. It becomes possible. (Fourth Embodiment) Next, a fourth embodiment embodying the first and third inventions will be described.

In the first to third embodiments, after the division correction by the analog divider 33 in the sensor amplifier 27, the corrected signal is converted into a digital signal by the A / D converter 38 in the combustion control device 36. are doing. Then, through the frequency analysis of the digital signal by the FFT processing unit 41,
Seeking vibration power. On the other hand, in the fourth embodiment, the signal is processed by another procedure as shown in FIG. That is, signal correction by division is performed after A / D conversion and FFT processing of an analog signal. Other configurations are the same as those of the first embodiment.

As shown in FIG. 22, a sensor amplifier 27 used in the fourth embodiment includes a first amplifier 34A connected to a DC / AC converter 31 instead of the analog divider in the first embodiment. And a second amplifier 34B connected to the integrator 32. On the other hand, the combustion control device 36 includes a first A / D converter 38A corresponding to the first amplifier 34A, and a second A / D converter 38B corresponding to the second amplifier 34B. The combustion control device 36 further includes an FFT processing unit 41 (FIG. 4) of the first embodiment.
Instead, an FFT / light quantity correction processing unit 73 surrounded by a broken line is provided. The processing unit 73 includes an FFT processing unit 74, a division division unit 75, an end determination unit 76 that determines the end of division division, and a corrected vibration power calculation unit 77.

The first amplifier 34A amplifies the vibration component from the DC / AC converter 31. Similarly, the second amplifier 34B amplifies the emission intensity component from the integrator 32.
At this time, the gain (gain) of the first amplifier 34A must completely match the gain of the second amplifier 34B.

The amplified vibration signal component has a first A / D
It is digitized by the converter 38A. Based on the digital signal, the FFT processing unit 74 calculates the power spectrum of the signal corresponding to each frequency in the frequency analysis with the intervention of the DSP 39. The division / divider 75 converts each power spectrum value into a second A / D converter 38
Divide by the emission intensity signal digitized by B.

The end determination unit 76 determines whether or not the processing in the division division unit 75 has been performed the number of times (N) corresponding to the resolution of the FFT processing. In other words, the processing in the division division unit 75 is repeated until all the power spectrum values given by the FFT processing are respectively subjected to division correction. Thus, the corrected power spectrum corresponding to each frequency is calculated over the entire measurement frequency range in the frequency analysis.

For example, the measurement frequency range in the frequency analysis is 0 to 200 Hz, and the resolution of the FFT processing is 20.
In the case of the 0 line, 200 correction power spectrum values corresponding to each frequency at 1 Hz intervals are calculated by the loop processing in the division division unit 75 and the end determination unit 76.

The corrected vibration power calculator 77 calculates the corrected vibration power by summing all the obtained corrected power spectrum values. According to the above example, 200
The sum of the corrected power spectrum values gives the vibration power corrected for the influence of the emission intensity.

The vibration power obtained according to the procedure of the fourth embodiment is equivalent to the vibration power obtained according to the procedure of the first embodiment, and can be used as an index of the air ratio control in the boiler.

Note that the first to fourth inventions are not limited to the configuration of the above-described embodiment, and may be arbitrarily changed without departing from the spirit of each invention as described below. (1) As the optical sensor 28, an optical sensor capable of converting flame light into an electric signal, such as a silicon photodiode or a phototransistor, may be used.

(2) In the combustion control methods of the first to fourth aspects of the present invention, the vibration power is obtained based on the detection signal from the optical sensor 28, and the vibration power is set to a predetermined vibration power. Any combustor that adjusts the opening of the air regulating valve 19 can be applied regardless of its type.
For example, it can be widely applied to general combustors such as furnace tube boilers and water tube boilers.

(3) In the first embodiment, the fuel flow rate is directly detected by the flow meter 24. Alternatively, the fuel flow rate may be obtained indirectly from the signal output to the control motor 18. .

(4) Examples of equipment utilizing the heat of the combustor include an air conditioner for a painting booth, a machine cleaning device, and the like, in addition to the boiler 1 and the industrial furnace 61. (5) As the amplitude representative value in the fourth invention, in addition to the second embodiment, a value obtained by taking a voltage value at regular intervals from FIG. 11B and squaring the value may be used. .
Alternatively, the square root of the squared value may be used as the representative amplitude value. Further, the maximum value of the amplitude in FIG.
The value may be used as a representative amplitude value. In short, any value that represents the amplitude of the vibration component may be used.

(6) The high-pass filter 71 used in the third embodiment may be used in the second embodiment. In this case, the analog divider 33 and the amplifier 34 in FIG.
, A high-pass filter 71 is interposed.

(7) In the fourth embodiment, the signal correction based on the emission intensity component obtained by the integrator 32 is employed. However, the fourth embodiment is combined with the signal correction method according to the second embodiment. Is also good.

[0111]

As described above in detail, in the first invention, the vibration component of the flame light and the component representing the emission intensity of the flame are respectively extracted from the electric signal converted by the optical sensor, and the vibration is extracted. > the ingredients by dividing the emission intensity representative component and corrects the vibration power. For this reason, it is possible to obtain the vibration power that generally exhibits substantially the primary characteristic with respect to the air ratio while keeping the influence of the flame emission intensity representative component on the vibration component constant. Therefore, efficient combustion can be realized by supplying an appropriate amount of air to the burner according to the fuel supply amount. Also, applicable combustors are more than those of the prior art.

In the second invention, before the amplitude of the electric signal is amplified by the optical sensor, the vibration component is divided by the emission intensity representative component, and the signal of the low frequency component in the obtained electric signal is removed by the high-pass filter. Then, only the signal of the high frequency component is taken out. For this reason, in addition to the effect of the first invention, an appropriate amount of air according to the fuel supply amount can be supplied to the burner without causing a significant increase in cost, and more efficient combustion can be realized.

In the third aspect, the light emission intensity component extracted from the electric signal from the optical sensor is used as the light emission intensity representative component. For this reason, in addition to the effect of the first or second invention, when applied to a combustor that emits less radiation from sources other than the flame, it is possible to obtain vibration power that exhibits primary characteristics with respect to the air ratio.

In the fourth aspect, the representative amplitude value extracted from the amplitude of the vibration of the electric signal by the optical sensor is used as the representative light intensity component. For this reason, in addition to the effects of the first or second aspect, even when applied to a combustor having a large radiation other than the flame, the influence of the radiation is removed and the vibration power showing the primary characteristic with respect to the air ratio is obtained. Can be. Accordingly, it can be applied to any combustor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion facility to which a combustion control method according to a first embodiment that embodies the first and third inventions is applied.

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is a functional block diagram illustrating signal processing in a sensor amplifier according to the first embodiment.

FIG. 4 is a functional block diagram illustrating signal processing in the combustion control device according to the first embodiment.

FIGS. 5A to 5C are waveform diagrams showing various electric signals processed in the sensor amplifier in the first embodiment.

FIG. 6 is a waveform chart showing a comparison between two types of electric signals obtained by processing in a sensor amplifier in the first embodiment.

FIG. 7 is a diagram showing a setting frequency of 200 Hz in the first embodiment.
7 is a graph showing the relationship between the air ratio and the vibration power in the case of [1].

FIG. 8 is a diagram showing a setting frequency of 300 Hz in the first embodiment.
7 is a graph showing the relationship between the air ratio and the vibration power in the case of [1].

FIG. 9 is a schematic configuration diagram of a combustion facility to which a combustion control method according to a second embodiment that embodies the first and fourth inventions is applied.

FIG. 10 is a functional block diagram illustrating signal processing in a sensor amplifier according to a second embodiment.

FIGS. 11A to 11E are waveform charts showing various signals processed in the sensor amplifier of the second embodiment.

FIGS. 12 (a) and 12 (b) are waveform diagrams respectively showing electric signals after DC / AC conversion in the second embodiment when there is no influence from radiation and when it is not.

FIGS. 13A and 13B are graphs showing power spectrum characteristics for each air ratio in the second embodiment when there is no radiation and when there is radiation.

FIGS. 14A and 14B are graphs showing changes in vibration power when the influence of radiation is corrected by the method of the first embodiment and when it is removed by the method of the second embodiment. You.

FIG. 15 is a graph showing the relationship between the air ratio and the vibration power in the second embodiment.

FIG. 16 is a functional block diagram illustrating signal processing in a sensor amplifier in a third embodiment embodying the first and second inventions.

17A and 17B are waveforms respectively showing electric signals when a low-frequency component in an electric signal after division is not removed by a high-pass filter and when it is removed in the third embodiment. FIG.

FIGS. 18 (a) and (b) show power spectrum characteristics when a low-frequency component in an electric signal after division is not removed by a high-pass filter and when it is removed in the third embodiment, respectively. It is a waveform diagram shown.

FIG. 19 shows the relationship between the air ratio and the vibration power when the upper limit of the measurement frequency range during FFT processing is low and the vibration power is more affected by the change in combustion state than the change in turbulence due to the air ratio. It is a graph.

FIG. 20 is a graph showing a relationship between an air ratio and a light emission intensity component in the third example.

21A shows the relationship between the air ratio and the vibration power when the signal of FIG. 20 is processed by a dedicated FFT analyzer, and FIG. 21B shows the relationship between the signal of FIG. 20 and the combustion control device of the third embodiment. 5 is a graph showing the relationship between the air ratio and the vibration power when the processing is performed at step (a).

FIG. 22 is a functional block diagram illustrating signal processing in a sensor amplifier and in a combustion control device according to a fourth embodiment of the present invention.

FIG. 23 is for explaining a conventional technique;
(A) is a waveform diagram showing a time change of an electric signal by an optical sensor for each air ratio, and (b) is a waveform diagram showing a frequency analysis of the electric signal of (a).

FIG. 24 is a graph showing the relationship between the air ratio and the luminous intensity component of the flame light in the prior art.

FIG. 25 is a graph showing the relationship between the air ratio and the vibration power when the set frequency is set to 20 Hz in the related art.

FIG. 26 is a graph showing the relationship between the air ratio and the vibration power when the set frequency is set to 50 Hz in the related art.

FIG. 27 shows a setting frequency of 300 Hz in the prior art.
7 is a graph showing the relationship between the air ratio and the vibration power in the case of [1].

FIGS. 28 (a) and (b) are waveform diagrams each showing a change over time of a vibration component and a light emission intensity component in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Boiler as a combustor, 5 ... Burner, 6 ... Fuel supply pipe, 9 ... Air supply pipe, 16 ... Fuel regulation valve, 19 ... Air regulation valve, 28 ... Optical sensor, 61 ... Industrial furnace as a combustor,
71: High-pass filter, F: Flame

Continued on the front page (72) Inventor Kazuya Tomatsu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Toshiharu Tachibana 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-2-8613 (JP, A) JP-A-60-213725 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23N 5/08

Claims (4)

(57) [Claims] An opening of a fuel adjusting valve provided on a fuel supply pipe and an opening of an air adjusting valve provided on an air supply pipe are adjusted respectively, and the opening degree of the fuel adjustment pipe is adjusted via the fuel supply pipe and the air supply pipe. By increasing or decreasing the fuel flow rate and air flow rate supplied to the burner of the combustor, the state of the flame of the burner is changed, the state of the flame light is converted into an electric signal by an optical sensor, and the amplitude of the electric signal is changed. After amplification, frequency analysis is performed to determine vibration power, which is an intensity integrated value in the entire frequency range, and the opening degree of the air adjustment valve is adjusted to match the vibration power to the optimum vibration power according to the fuel flow rate at that time. the combustion control method to adjust, and components representing the luminous intensity of the vibration component and the flame of the flame light from the electric signal by the optical sensor respectively extracted, the vibration power by the emission intensity representative component In order to effect constant, combustion control method characterized by vibration Ingredient was to obtain the same vibration power is divided by the emission intensity representative component. 2. Prior to amplifying the amplitude of the electric signal, a vibration component is divided by a light emission intensity representative component, a low frequency component signal in the obtained electric signal is removed by a high-pass filter, and a high frequency component signal is removed. 2. The combustion control method according to claim 1, wherein only the fuel is taken out. 3. The combustion control method according to claim 1, wherein the emission intensity representative component is an emission intensity component extracted separately from a vibration component from an electric signal from an optical sensor. 4. The combustion control method according to claim 1, wherein the emission intensity representative component is an amplitude representative value extracted from an amplitude of a vibration component of an electric signal by an optical sensor.