JPH01167522A - Device for detecting blown-off state of burner flame - Google Patents

Abstract

PURPOSE:To detect a proper blown state and increase a heating efficiency by a method wherein an amount of supplied air for a combustion part is adjusted in response to a rate of variation of a power spectrum integrated value of a low frequency band got from a detected signal of an optical sensor and a rate of variation of a power spectrum ratio. CONSTITUTION:An optical sensor 13 arranged within a combustion furnace 1, a flame condition discriminating unit 15 and an air flow rate limiting device 12 are provided. A rate of variation of a power spectrum integrated value of a low frequency band and a rate of variation of a power spectrum ratio are calculated in response to a power spectrum got through an analyzation of frequency of the sensed signal of the optical sensor 13 by a flame state discriminating unit 15. When a multiplicity of both rates of variation becomes positive, the flame state discriminating unit 15 may output a limiting signal to an air flow rate limiting device 12 to meter an adjusting valve 9 so as to perform a positive stoppage of supplying air. In turn, a control signal is outputted to an informing means such as a lamp 16 and the like to inform an operator that a flame 14 becomes a blown-off state.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a burner flame blown state detection device.

(Prior art) Conventionally, as an example of a combustion control device, a photoelectric conversion element such as a photodiode is placed in a combustion furnace, and a power spectrum is obtained by a frequency analysis means based on the detection signal, and calculations are made using this power spectrum. It is known that the amount of air supplied to the burner is adjusted according to the power spectrum ratio.

In this case, the power spectrum ratio is calculated as follows.

For example, in a combustor that uses a burner tile flame holder,
Heavy oil 101:/11 combustion, exhaust gas 02% 1,4.2
．． 1.3.2.3.9.4.6 When the power is changed to 6.0%, the frequency analysis means is shown in Fig. 4 based on the optical power oscillation signal obtained from a photoelectric conversion element such as a Ge photodiode. Obtain the power spectrum as shown. Exhaust gas 0
An increase of 2% increases the frequency at a certain frequency (15 in the example in Figure 4).
Hz) and higher bands are larger. In order to express this feature numerically, we calculate the integral value for all frequency bands as A, and the integral value for bands above a specific frequency as B, and compare them (see Figure 5). ), the power spectrum ratio C is calculated.

When this power spectrum ratio C is expressed with 02% exhaust gas as the horizontal axis, it has an upwardly convex shape as shown in FIG.

(Problem to be solved by the invention) By the way, the conventional combustion control device as described above.

When applying this to a combustion device to heat a product, depending on the blowing speed of the fuel atomization air and the speed of blowing out the combustion air, the flame may be blown away. However, although the conventional combustion control device described above has a photoelectric conversion element that detects the flame state, it cannot detect the blown-off state as described above, resulting in a reduction in heating efficiency. . This problem is particularly noticeable in furnaces where the pilot burner is always in the ignited state, such as furnaces that keep the internal temperature constant by controlling the burners on and off. It was even possible to continue the air and fuel supply as in the situation.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a burner flame blown state detection device that can appropriately detect the blown out state and improve heating efficiency.

(Means for Solving the Problems) The means for achieving the above object will be explained with reference to FIGS. 1 and 3. , calculate the rate of change of the power spectrum integral value and the rate of change of the power spectrum ratio in the low frequency band based on the noise spectrum obtained by frequency analysis of the detection signal of the original sensor 13, and determine if the product of both rates of change is positive. flame condition determiner 1 which indicates a control signal indicating this.
5, and an air flow rate restricting device 12 that controls the regulating valve 9 in accordance with the control signal.

Note that when the product of the rate of change is positive, it is determined that the state is blown away based on the following reason. In other words, as shown in Figure 4, the power spectrum ram generally reduces exhaust gas by 0.2% in the frequency range above a specific frequency (15Hz in Figure 4).
increases as
In the frequency range below Hz, the exhaust gas tends to decrease as it increases, and these frequencies define a specific frequency band and a low frequency band. The integrated value of the power spectrum in the low frequency band shows a decreasing tendency as shown in FIG. 3 when the horizontal axis is 02% of the exhaust gas. Also,
When calculating the power spectrum ratio C, as mentioned above, as shown in Figure 3, as the exhaust gas 02% increases, it increases up to a predetermined value, and when it exceeds a predetermined value, it tends to decrease due to the flame blow-off phenomenon. . In this way, in the flame blown state, unlike other states, the product of both becomes positive because the integral value of the power spectrum 2m in the low frequency band and the power spectrum ratio C both decrease. In this case, it is determined that the flame is in a state of being blown away.

(Function) With the above configuration, when the product of the rate of change of the power spectrum integral value in the low frequency band and the rate of change of the power spectrum ratio becomes positive, the present invention sends a control signal to this effect to the air supply amount adjusting means and the alarm. Since the air is output to the burner and the amount of air supplied to the burner is adjusted, if the flame is blown out, it can be detected and combustion can be controlled to increase heating efficiency.

(Embodiment) Hereinafter, a burner flame blown state detection device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a burner flame blown state detection device according to an embodiment of the present invention.

In FIG. 1, a burner 2 installed in a furnace 1 has a fuel pipe 3. Fuel pulverization air piping 4 and combustion air piping 5
is connected.

A flow meter 6 and a control valve 7 are provided in the middle of the fuel pipe 3, a control valve 8 is provided in the middle of the fuel pulverized air pipe 4, and a control valve 9 is provided in the middle of the appearance air pipe 5. ing.

Note that a thermometer 10 is disposed inside the furnace 1, and a temperature controller 11 is connected to this thermometer 10.

The temperature controller 11 takes in the detection data of the thermometer 10 and the detection data of the flow meter 6, controls the control valve 7 to adjust the combustion state, and maintains the temperature in the furnace 1 at a constant value. A control signal obtained based on the data is output to the air flow rate restricting device 12. The air flow rate restriction device 12 corrects the control signal taken in from the temperature controller 11 according to a correction coefficient signal output from a flame condition determiner 15 (described later), and outputs the corrected signal to the control valve 9. The amount of combustion air supplied is adjusted by

Furthermore, an optical sensor 16 is provided within the furnace 1 . The optical sensor 13 takes in the optical power emitted from the flame 14 of the burner 2, photoelectrically converts it, and outputs it as a combustion detection signal. A flame condition determiner 15 is connected to the optical sensor 13 . The flame state determiner 15 receives the combustion detection signal and executes a control program stored in a storage means (not shown) to perform the following processing.

That is, the combustion detection signal is frequency-analyzed to calculate the power spectrum, and the integrated value A of the power spectrum of all frequency bands, the integrated value B of the power spectrum of a specific frequency band, and the integrated value of the power spectrum of the low frequency band are calculated. Then, calculate the power spectrum ratio C=B/A. Then, while continuing to perform such calculations in sequence, the rate of change E for the power spectrum ratio C is calculated for each time difference Δ as C-C' E=□ t C': previous data, and the low frequency Calculate the rate of change F with respect to the integral value of the power spectrum of the band as the previous data, and indirectly determine whether the product EXE' of both rates of change is positive. If it is larger than 0, it is determined that the flame 14 is in a blown-off state as explained using FIG. 3, and a restriction signal indicating this is sent to the air flow rate restriction device 12. Output to.

Further, a lamp 16 as a notification means is connected to the flame condition determiner 15, and the flame condition determiner 15 outputs a restriction signal to the air flow rate restricting device 12 and simultaneously outputs a restriction signal to the lamp 16.
A control signal is output to the lamp 16 to light the lamp 16 to notify that the blowout condition has occurred. Note that the notification means is not limited to the lamp 16, but may be a device that emits an alarm sound.

The operation of the burner flame blowout detection device configured as described above will be explained below with reference to the flowchart of FIG. 2.

First, the optical sensor 13 takes in the optical power based on the flame 14, photoelectrically converts it, and outputs a combustion detection signal to the flame state determiner 15.

Then, the flame state determiner 15 takes in the combustion detection signal (step (hereinafter referred to as ST) 31) and calculates a power spectrum (S'12).

Next, the integral value A of the power spectrum of all frequency bands, the integral value B of the power spectrum of a specific frequency band, and the power spectrum ratio C== B/A are sequentially calculated (
8T33, 34, 35).

Subsequently, the integrated value of the power spectrum in the low frequency band is calculated (ST36).

Furthermore, the rates of change E and F are calculated for each time difference Δ, and at the same time it is determined whether the product of both rates of change, E x F, is greater than 0. The above-mentioned operation is continued until it becomes larger.Then, if the determination is ``YES'' at step 5T38, a restriction signal is output to the air flow restriction device 12, and the control valve 9 is throttled to ensure that the air supply is stopped. On the other hand, a control signal is output to the lamp 16 to turn on the lamp 16 and prompt the operator to ignite the flame 14.
It is notified that it has become blown away (ST39).

In this manner, when the fire is blown away, the air supply can be immediately stopped to ensure extinguishment, thereby increasing heating efficiency.

In this embodiment, since the lamp 16 is turned on, the operator can be appropriately notified of the flame blown state, which can be useful for the operation of the combustion apparatus.

(Effects of the Invention) As explained above, the present invention multiplies both the rate of change of the low frequency band power spectrum integral value and the rate of change of the power spectrum ratio, and when this multiplication value becomes positive, a blowout state occurs. Since the amount of air supplied to the combustion section is adjusted according to the result of this determination, it is possible to properly detect the flame blowout state and control combustion to improve heating efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a burner flame blown state detection device according to an embodiment of the present invention, Fig. 2 is a flowchart showing an example of the operation of the device, and Fig. 3 shows the power spectrum ratio and the power spectrum in the low frequency band. A characteristic diagram showing an example of an integral value, Fig. 4 is a schematic diagram showing a power spectrum showing the frequency analysis result of the vibration signal of the optical power of the flame obtained by a photoelectric conversion element, and Fig. 5 shows the frequency band of the power spectrum. It is a schematic diagram. DESCRIPTION OF SYMBOLS 1... Furnace, 2... Burner, 12... Control valve, 13... Optical sensor, 14... Flame, 15.
...Flame status determiner. Patent Applicant: Toyota Motor Corporation
zl -10s p4

Claims (1)

[Claims] Based on the optical sensor installed in the combustion furnace and the frequency analysis data of the detection signal of this optical sensor, the rate of change of the low frequency band power spectrum integral value and the rate of change of the power spectrum ratio are calculated, and the rate of change of both rates of change is calculated. A burner flame blown state detection device comprising: control means for outputting a control signal indicating this result when the product is positive; and means for adjusting the amount of air supplied to the combustion section in accordance with the control signal.