JP3862425B2 - Flame state detection method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for detecting abnormal combustion in combustion equipment that burns while forming a flame such as a water heater or a boiler.
[0002]
[Prior art]
In a burner such as a water heater, the amount of combustion is changed according to the load. At this time, in order to appropriately set the air ratio according to the amount of combustion, it is necessary to supply an appropriate ratio of air. For this reason, in the prior art, a method is used in which an air amount corresponding to the combustion amount is set in advance and the combustion amount and the air amount are controlled according to the load.
In the combustion of such a combustion device, these abnormal states may include an incomplete combustion state in which the amount of CO generated from the combustion device increases.
Further, for example, in a combustion apparatus such as a water heater, as shown in FIG. 2, a configuration in which burners having substantially the same shape and configuration are arranged side by side in a predetermined burner juxtaposition direction is employed. As an abnormal state of such a combustion device, for example, a single burner may be clogged with an obstructive substance, and a state in which a red flame with a long flame length extends from the burner may occur. . This state is called a partially incomplete combustion state. In such a red fire combustion state, the generation of soot accompanying combustion is large, and the system is advanced in the direction of closing the exhaust passage. Therefore, it is necessary to detect this abnormal state and take appropriate measures.
As a technique for performing combustion control and air ratio control using an optical technique, a technique using a color sensor disclosed in Japanese Patent Application Laid-Open No. 59-35718 can be cited. This performs combustion control and air ratio control using the fact that the color of the flame is related to the amount of air. In the case of this example, a monitoring area of the optical sensor is set at the so-called flame center, and light in the wavelength range of about 400 to 700 nm is monitored.
[0003]
[Problems to be solved by the invention]
Now, in the combustion state, the flame length of the flame in both states is significantly different between the state where the combustion occurs as a blue fire and the state where the combustion occurs as a red fire (see FIG. 2). However, a technique for detecting an abnormality in the combustion state based on such flame characteristics (characteristic that the flame length changes) has not been known so far.
On the other hand, when trying to detect the change of the spectrum in the optical signal generated from almost the center of the flame using the color sensor, it becomes an analysis in the state where the optical signal is always present, so it is not easy to check the presence of the signal, Since it is necessary to see changes in the spectral intensity depending on the frequency, the configuration of the detection / discrimination system becomes complicated, and problems to be solved remain until the practical range is reached.
Therefore, an object of the present invention is to obtain a technique capable of discriminating the state of a flame generated in a combustion apparatus with a rational and simple method and apparatus, unlike the technique conventionally performed.
[0004]
[Means for Solving the Problems]
In order to achieve this object, the characteristic means of the flame state detection method for detecting the state of the flame by detecting an optical signal generated from the flame formed in the combustion device according to the present invention is such that the flame is in a blue fire state in the combustion device. A light sensor output from a light sensor having a sensor detection area in a red flame formation area where the flame burns in a red fire state in an area on the lower side of the flame formation direction than the blue flame formation area burning in The purpose is to detect the state of the flame based on the sensor output.
The combustion abnormality targeted by this method mainly corresponds to the case where combustion occurs while forming a red fire. As explained earlier, because the flame length is different between the blue fire combustion state and the red fire combustion state, the red flame in which the flame burns in the red fire state in the region on the lower side of the flame formation direction from the blue flame formation region. Abnormality can be detected by detecting an optical signal within the formation region. That is, in the blue fire combustion state, there is almost no light sensor output, and since a large light sensor output can be detected only in an abnormal state where the fire burns with red fire, it is easy and reliable to identify and detect abnormality .
[0005]
Further, when the combustion apparatus is provided with a plurality of combustion burners arranged in parallel in a predetermined burner juxtaposition direction, the optical sensor having a sensor detection area that extends in the juxtaposition direction is used. When the output value from the optical sensor is larger than a predetermined first determination value, it is determined that one of the combustion burners is in a partially abnormal state in a red fire combustion state .
Conventionally, it has been difficult to detect such a partial incomplete combustion state based on the CO concentration or the like, but a flame having a relatively long flame length only on the downstream side of the flame formation direction of the burner in which incomplete combustion occurs. Can be reliably detected, and the partial abnormal combustion state can be captured.
[0006]
Further, in the method of determining the occurrence of red fire, including the first determination value for red fire determination described above, the second determination value is smaller than the first determination value, and the optical sensor output is predetermined. Is larger than the second determination value and smaller than the first determination value, the combustion device is in a state of burning while forming a blue fire, but the amount of generated CO is large and the blue fire is incomplete combustion. It is preferable to adopt a configuration in which it is determined that the state is present.
In the combustion movable state of today's combustion apparatus, when the combustion flame is red fire, it is an abnormal state, and such an abnormal state is generally considered to be an unfavorable CO gas generation state. May occur for different reasons. In other words, in the combustion apparatus, this situation may occur due to the blockage of the exhaust side and the supply side with use over time, but this only causes a slight increase in the amount of CO gas generated. Absent.
On the other hand, when the closed state of the individual burner advances, only the combustion flame in this burner suddenly becomes red fire with the control of the air ratio. In such a case, the optical sensor output changes rapidly as will be shown later. Therefore, the situation of the combustion apparatus can be accurately grasped by providing the two determination values as described above.
[0007]
As a wavelength region of an optical signal used for such detection, a frequency range of 600 nm to 1000 nm (more preferably 700 nm to 1000 nm) is preferable because strong light emission occurs during red fire combustion.
[0008]
The flame state detection apparatus using the method described so far is configured as follows.
That is, in configuring a flame state detection device that detects a light state by detecting an optical signal generated from a flame formed in the combustion device,
In the combustion apparatus, an optical sensor having a sensor detection area is provided in a red flame formation area where the flame burns in a red fire state, in an area on the lower side of the flame formation direction from a blue flame formation area where the flame burns in a blue fire state. , by the light sensor output from the optical sensor, comprising a determining means for determining the combustion state, the combustion device, a predetermined burner arrangement direction, if those having been arranged a plurality of combustion burners In addition, when the optical sensor in which the sensor detection area extends in the juxtaposed direction is used, and the output from the optical sensor is larger than a predetermined first determination value, the determination means may It is determined that the burner is in a partial abnormal state where the burner is in a red fire combustion state.
With this configuration, it is possible to determine the flame state according to the method described so far.
[0009]
Further, when the determination means has a second determination value smaller than the first determination value, and the optical sensor output is larger than a predetermined second determination value and smaller than the first determination value, the combustion Although the apparatus is in a state of burning while forming a blue fire, it is preferable to determine that the apparatus is in a blue fire incomplete combustion state in which a large amount of CO is generated.
By setting such two large and small judgment reference values, similarly, in the combustion that may be considered to be in the abnormal region, the red fire combustion region, the partial red fire combustion region, and the blue fire incomplete combustion region Can be distinguished and discriminated.
Even in the case of configuring the apparatus in this way, it is possible to use a light having a wavelength in the region wavelength of 600 nm to 1000 nm (more preferably, a wavelength of 700 to 1000 nm) as the wavelength of the optical sensor output. Is preferable because of
In the case of the configuration of the above-described device, since the magnitude of the optical sensor signal intensity and the determination value are compared, it is not always necessary to provide a plurality of sensors, and the device system becomes extremely simple.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present application will be described with reference to the drawings.
FIG. 1 shows a water heater 1 that is an example of a combustion device that employs the flame state detection device of the present application.
The water heater 1 includes a water heater body 2 that forms a combustion chamber, a combustion device 4 that is provided in the vicinity of the combustion air suction portion 7 that is a lower position of the water heater body 2, and a downstream side of the combustion device 4 (see FIG. 1 and the heat exchanger 5 provided on the upper side.
Fuel gas is supplied to the combustion device 4 via a fuel supply path 6, and secondary air is sucked from a combustion air suction portion 7 provided at a predetermined site in the vicinity of the combustion device 4 for combustion. Served for use. To adjust the supply amount of the fuel gas supplied through the supply passage 6 and the primary air amount mixed with the supply passage 6 (this is supplied from the primary air supply passage 3). The adjusting valve 8 is adjusted based on the combustion control command generated by the combustion control command generating means 9. As a result, the amount of fuel gas supplied to the combustion device 4 and the amount of air sucked are adjusted by adjusting the valve opening, and the combustion state is adjusted.
[0011]
The combustion apparatus 4 includes a plurality of combustion burners 40 having substantially the same structure in parallel in the direction in which the burners are arranged in the horizontal direction of FIG. Therefore, the flame outlet of the burner extends in the front and back direction. The combustion apparatus 4 has a structure that forms a continuous flame in the front and back direction of the paper in FIG. 1 and is configured to form a plurality of divided flames in the left-right direction.
Water is supplied to the heat exchanger 5 through the water supply channel 10 and absorbs heat generated by the combustion of the combustion device 4 to generate hot water.
[0012]
The above is the basic structure of the water heater 1, but in the normal combustion state, the arrival position of the flame (blue fire in the normal combustion state) formed in the combustion device 4 (where the flame is formed) The area that is indicated is called a blue flame forming area).
[0013]
Now, the characteristic configuration of the present application will be described below.
As shown in FIG. 1, at a position immediately upstream of the heat exchanger (an example of a heater) 5 and downstream of the blue flame formation region A (this position is in a normal blue fire combustion state). In this case, the optical sensor 11 is provided on the side of the position where the end position of the flame does not reach substantially, and the position where the flame reaches only when it becomes red fire. At the monitoring position B of the optical sensor 11, the flame is in a blue fire combustion state, and no flame can be recognized as long as it is visually observed. In the drawing, for easy explanation, the detection area of the light sensor is located at the tip position of the blue fire, but the blue fire is substantially terminated below this position.
This optical sensor 11 measures an optical signal intensity of a wavelength of 600 nm to 1000 nm that is substantially emitted from a flame, and is specifically a photodiode type optical sensor provided with Si as a light receiving element. The detection area of the optical sensor 11 is orthogonal to the flame forming direction, which is the vertical direction in FIG. 1, as indicated by a one-dot chain line, and extends in the direction in which the combustion burners are juxtaposed.
Further, the combustion apparatus is provided with a microcomputer 12 provided with combustion control command generation means 9 that receives the optical signal intensity measured by the optical sensor 11 and generates a combustion control command. Therefore, in the present application, the control valve 8 receives the control command generated by the combustion control command generating means 9 and operates.
Further, the microcomputer 12 determines that the incomplete combustion state of red fire in which combustion is generated by red fire when the optical sensor output from the optical sensor 11 is larger than a predetermined first determination value. Judgment means 13 is provided. Here, the first determination value is about 0.1 V when described with reference to FIG.
Further, the determination means 13 has a second determination value that is smaller than the first determination value, and when the optical sensor output is larger than the predetermined second determination value and smaller than the first determination value, the combustion device Is in a state of burning while forming a blue fire, but it is determined to be in an incomplete combustion state of blue fire with a large amount of generated CO. Here, the second determination value is about 0.005 V when similarly described with reference to FIG.
Therefore, the determination means 13 can alternatively determine whether the combustion state is a red fire combustion state or a blue fire combustion state but a state in which a large amount of CO is generated.
The determination result by the determination unit 13 is configured to be output via the output unit 14.
[0014]
Hereinafter, the operation of the determination unit 13 described above will be described.
In the description, as a combustion state, a part of the burners shown in FIG. 2 (a) is in a partially closed state, and a state in which red fire is generated from this burner is a partial red fire combustion state. This is called (partial incomplete combustion state), and as shown in FIG. 2 (b), the state in which all combustion burners are burning with blue fire is the whole blue fire combustion state (normal combustion state and whole incomplete combustion state). Called.
Now, the spectrum of the optical sensor output in the partially incomplete combustion state in the case where such combustion pattern classification is performed is shown in FIG. 3, and in the whole blue fire combustion state, FIG. The vertical axis of these drawings indicates the count number, and the greater the count number, the higher the spectral intensity.
In these drawings, the air ratio λ (actual supply air amount / theoretical air amount) is changed.
Referring to FIG. 3 corresponding to the partially incomplete combustion state, the optical sensor output increases exponentially as the wavelength increases from the portion having the wavelength of about 450 nm. In particular, an increasing tendency is remarkable in a wavelength region of 600 nm or more (700 nm or more). That is, as in the present application, a partial red fire combustion state (partial) is detected by detecting an optical signal in a wavelength region of, for example, 600 nm or more with an optical sensor having a detection region at a position downstream of the blue fire combustion state region. It can be seen that the incomplete combustion state can be detected with good discrimination.
Referring to FIG. 4 corresponding to the overall blue fire combustion state (normal combustion state and overall incomplete combustion state), first, a signal region having a significant signal intensity is a region having a wavelength of about 700 nm or more as compared with FIG. It can be seen that the overall signal intensity is lower than that of FIG. Therefore, 4 in the blue fire combustion state and the red fire combustion can be discriminated in the method of the present application, as will be understood from the comparison in FIG. 5 described later.
[0015]
Next, FIG. 5 shows the relationship between the optical sensor output (V), the CO generation amount (ppm), and the air ratio corresponding to the combustion state.
In the same figure, it corresponds to the state where the degree of incomplete combustion is high (the air ratio is low) as it goes to the right side in the figure. Furthermore, in the portion indicated by each symbol, partial imperfection corresponds to the case where some burners are causing red fire combustion as described above, and total imperfection means that all burners are Although it burns with blue fire, it corresponds to the state where the amount of CO generation is increasing.
Furthermore, in the partially incomplete part, the front, front 2, back 1, and back 2 are described in parentheses because the burner causing red fire combustion is on the near side as seen from the optical sensor. (Denoted as front) or in the rear (denoted as deep). That is, for example, “front 2” corresponds to a situation in which the second burner on the near side in FIG. 2 with respect to the optical sensor causes red fire combustion for some reason. Furthermore, “large” and “small” indicate the amount of combustion (specifically, 500 Kcal and 4000 Kcal).
Hereinafter, the relationship between the optical sensor output and the combustion state will be described with reference to FIG. 5. In the normal combustion region shown in FIG. 5, the output value is small. However, even when the combustion state is, for example, a state where the air ratio is small and the amount of CO generated is increased, the optical sensor output only shows a slight increase tendency.
On the other hand, when some of the combustion burners become abnormal and red-fire combustion occurs, the optical sensor output increases stepwise to a predetermined value (up to about 1 V in the case of the figure). This factor is considered to be due to the relationship between the detection range of the optical sensor and the detection wavelength.
Therefore, as shown in FIG. 5, when the method of the present application is adopted, it is possible to set the first determination value to discriminate between the blue fire combustion and the red fire combustion and set the second determination value. Thus, even in the blue fire combustion state, it is possible to determine a state where the amount of generated CO is large.
[0016]
[Another embodiment]
In the above embodiment, a light receiving element having Si as a main material as an element material has been shown as an optical sensor. Examples of such a material include Ge, InGaAs, GaAlAs, GaAs, CdS, CdSe, and the like. Available.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a combustion apparatus of the present application. FIG. 2 is a schematic diagram showing a detection principle of red fire combustion. FIG. 3 is a spectrum diagram showing a change state of an optical sensor output during partial incomplete combustion. ] Spectral diagram showing changes in optical sensor output during complete incomplete combustion. [Fig. 5] Diagram showing difference in optical sensor output in normal combustion area, overall incomplete combustion area, and partial incomplete combustion area.
4 Combustion device 11 Optical sensor 13 Judgment means 14 Output means 40 Combustion burner

Claims (6)

A flame state detection method for detecting a light state by detecting an optical signal generated from a flame formed in a combustion device,
In the combustion apparatus, from the optical sensor having a sensor detection area in the red flame formation area where the flame burns in the red fire state, in the area lower in the flame formation direction than the blue flame formation area where the flame burns in the blue fire state. In obtaining the optical sensor output, in detecting the flame state by the optical sensor output ,
When the combustion device is provided with a plurality of combustion burners arranged in parallel in a predetermined burner juxtaposition direction,
When the optical sensor having a sensor detection area extending in the juxtaposed direction is used and the output from the optical sensor is larger than a predetermined first determination value, any one of the combustion burners is in a red fire combustion state. A flame state detection method for determining that a partial abnormal state exists . When the second determination value is smaller than the first determination value, and the optical sensor output is larger than a predetermined second determination value and smaller than the first determination value, the combustion device forms a blue fire. The flame state detection method according to claim 1, wherein the flame state is determined to be in an incomplete combustion state with a large amount of CO generated in a burning state but with a large amount of CO. Flame detection method according to claim 1 or 2 for measuring the optical signal intensity of the wavelength 600nm~1000nm emitted from the flame. A flame state detection device for detecting a light state by detecting an optical signal generated from a flame formed in a combustion device,
In the combustion apparatus, an optical sensor having a sensor detection area is provided in a red flame formation area where the flame burns in a red fire state, in an area on the lower side of the flame formation direction from a blue flame formation area where the flame burns in a blue fire state. , by the light sensor output from the light sensor, comprising a determining means for determining the combustion state,
When the combustion device is provided with a plurality of combustion burners arranged in parallel in a predetermined burner juxtaposition direction,
When the optical sensor having a sensor detection area extending in the juxtaposed direction is used, and the optical sensor output from the optical sensor is larger than a predetermined first determination value, the determination unit is configured to use one of the combustion sensors. A flame state detection device that determines that the burner is in a partially abnormal state in which a red fire combustion state is present . When the determination means has a second determination value smaller than the first determination value, and the optical sensor output is larger than a predetermined second determination value and smaller than the first determination value, the combustion device The flame state detection device according to claim 4, wherein the flame state detection device determines that the combustion is in an incomplete combustion state with a large amount of CO generated while being in a state of combustion while forming a blue fire. 6. The flame state detection device according to claim 4 or 5, wherein the optical sensor is an optical sensor including at least one of Si, Ge, InGaAs, GaAlAs, GaAs, CdS, and CdSe as a light receiving element material.

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