JP2022077260A - Flame detector, boiler, flame detection method and combustion control method - Google Patents

Abstract

To detect a flame state in detail.SOLUTION: A flame detector 5 comprises a spectroscopic unit 521 that splits light of a flame into at least a first wavelength component and a second wavelength component, and a detection unit 527 that detects a temperature of the flame based on a comparison result between a strength ratio of the first wavelength component and the second wavelength component and a reference strength ratio that changes depending on a temperature.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a flame detector, a boiler, a flame detection method and a combustion control method.

In equipment such as boilers, flames are generated by burning fuel. Such equipment is provided with a flame detection device that detects the state of the flame. For example, Patent Document 1 discloses a technique relating to a flame detecting device for detecting a state of a flame formed by a burner provided in a boiler furnace.

Japanese Unexamined Patent Publication No. 2005-016839

By the way, according to the conventional flame detection device, the presence or absence of a flame can be detected. However, in order to more appropriately control combustion in equipment such as boilers, it is desirable to detect the state of the flame in more detail by obtaining information other than the presence or absence of the flame.

An object of the present disclosure is to provide a flame detection device, a boiler, a flame detection method and a combustion control method capable of detecting a flame state in detail.

In order to solve the above problems, the flame detection device of the present disclosure has a spectroscopic unit that disperses the light of the flame into at least the first wavelength component and the second wavelength component, and the intensity of the first wavelength component and the second wavelength component. A detection unit that detects the temperature of the flame based on the comparison result between the ratio and the reference intensity ratio that changes depending on the temperature is provided.

The first wavelength component and the second wavelength component may be the wavelength component of visible light.

The flame may be formed by a burner provided in the furnace of the boiler.

In order to solve the above problems, the boiler of the present disclosure includes a furnace, a burner provided in the furnace, and a spectroscopic unit that disperses the light of the flame formed by the burner into at least a first wavelength component and a second wavelength component. A flame detection device having a detection unit for detecting the temperature of a flame based on a comparison result between an intensity ratio of a first wavelength component and a second wavelength component and a reference intensity ratio that changes depending on the temperature. A control device for controlling the combustion of the burner based on the temperature of the flame detected by the detection unit is provided.

In order to solve the above problems, the flame detection method of the present disclosure has a step of splitting the light of the flame into at least a first wavelength component and a second wavelength component, and an intensity ratio between the first wavelength component and the second wavelength component. And the step of detecting the temperature of the flame based on the comparison result with the reference intensity ratio which changes depending on the temperature.

The first wavelength component and the second wavelength component may be the wavelength component of visible light.

The flame may be formed by a burner provided in the furnace of the boiler.

In order to solve the above problems, the combustion control method of the present disclosure includes a step of dispersing the light of a flame formed by a burner provided in a boiler furnace into at least a first wavelength component and a second wavelength component, and a first step. Based on the step of detecting the temperature of the flame based on the comparison result between the intensity ratio of the wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature, and based on the detected temperature of the flame, Includes steps to control the burning of the burner.

According to the present disclosure, the state of the flame can be detected in detail.

FIG. 1 is a schematic view showing a boiler according to the present embodiment. FIG. 2 is a schematic view showing a flame detection device according to the present embodiment. FIG. 3 is an explanatory diagram for explaining the principle of the two-color thermometer.

An embodiment of the present disclosure will be described below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and the present disclosure is not limited unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate explanations, and elements not directly related to the present disclosure are omitted from the illustration. do.

FIG. 1 is a schematic diagram showing a boiler 1 according to the present embodiment. As shown in FIG. 1, the boiler 1 includes a fireplace 2, a flue 3, a burner 4, a flame detection device 5, and a control device 6.

The furnace 2 is a furnace that generates combustion heat by burning a fuel such as ammonia or pulverized coal. The furnace 2 has a tubular shape (for example, a rectangular tubular shape) extending in the vertical direction. In the furnace 2, high-temperature combustion gas is generated by burning the fuel. The bottom of the fireplace 2 is provided with a discharge port 2a for discharging ash generated by combustion of fuel to the outside.

The flue 3 is a passage that guides the combustion gas generated in the fireplace 2 to the outside as exhaust gas. The flue 3 is connected to the upper part of the fireplace 2. The flue 3 has a horizontal flue 3a and a rear flue 3b. The horizontal flue 3a extends horizontally from the upper part of the fireplace 2. The rear flue 3b extends downward from the end of the horizontal flue 3a.

The boiler 1 includes a superheater (not shown) installed in the upper part of the furnace 2 or the like. In the superheater, heat exchange is performed between the combustion heat generated in the furnace 2 and water. As a result, water vapor is generated. Further, the boiler 1 may be provided with various devices (for example, a reheater, an economizer, an air preheater, etc.) not shown in FIG.

The burner 4 is provided on the lower wall portion of the furnace 2. A plurality of burners 4 are provided in the furnace 2 at intervals in the circumferential direction of the furnace 2. Although not shown in FIG. 1, the plurality of burners 4 are provided at intervals in the extending direction (vertical direction) of the furnace 2. The burner 4 injects and burns fuel such as ammonia or pulverized coal. For example, as the burner 4, a composite burner that can be injected into the furnace 2 using ammonia and pulverized coal as fuel can be used.

The burner 4 has a cylindrical shape. The tip of the burner 4 is arranged in the furnace 2. The fuel supplied to the burner 4 is injected into the furnace 2 from the tip of the burner 4 and burned. As a result, the flame F is formed in the furnace 2. The boiler 1 is provided with an air supply mechanism (not shown) that supplies air to the burner 4. The ignition furnace 2 is provided with an ignition device (not shown) for igniting the fuel injected from the burner 4. The fuel injected from each burner 4 into the furnace 2 together with the air is ignited and burned by the ignition device.

The flame detection device 5 detects the state of the flame F. The flame detection device 5 may be provided for a part of the burners 4 among the plurality of burners 4, or may be provided for each burner 4. The flame detection device 5 has a light collecting unit 51 and an analysis device 52. The light collecting unit 51 collects the light of the flame F formed by the burner 4. The light collecting unit 51 is provided in the vicinity of the burner 4 in the wall portion of the furnace 2. The light collecting unit 51 has a tubular shape. The tip of the light collecting unit 51 is arranged in the furnace 2 in a posture facing the flame F. The condensing unit 51 is provided with a condensing lens (not shown) that condenses the light of the flame F. The analysis device 52 analyzes the light of the flame F condensed by the condensing unit 51. Thereby, the state of the flame F is detected. The detailed configuration of the flame detection device 5 will be described later.

The control device 6 controls the combustion of the burner 4. Specifically, the control device 6 controls the combustion of the burner 4 by controlling the operation of various devices of the boiler 1. In particular, in the boiler 1, the detection result by the flame detection device 5 is output to the control device 6, and the control device 6 controls the combustion of the burner 4 based on the detection result by the flame detection device 5. Thereby, it is realized that the combustion in the boiler 1 is appropriately controlled. The details of the control of the combustion of the burner 4 by the control device 6 will be described later.

FIG. 2 is a schematic view showing the flame detection device 5 according to the present embodiment. As shown in FIG. 2, in the flame detection device 5, the condensing unit 51 and the analysis device 52 are connected via an optical fiber cable 53. The light of the flame F collected by the light collecting unit 51 is transmitted to the analysis device 52 via the optical fiber cable 53.

The analyzer 52 includes a spectroscopic unit 521 (specifically, a first spectroscopic unit 521a and a second spectroscopic unit 521b), a photoelectric sensor 522a, 522b, 522c, a log amplifier 523a, 523b, 523c, and a variable gain AC amplifier. It includes a 524, a bandpass filter 525, an RMS-DC converter 526, and a detection unit 527.

Hereinafter, when the photoelectric sensors 522a, 522b, and 522c are not particularly distinguished, they are also simply referred to as photoelectric sensors 522. When the log amplifiers 523a, 523b, and 523c are not particularly distinguished, they are also simply referred to as log amplifiers 523.

The spectroscopic unit 521 disperses the light of the flame F into a specific wavelength component. The spectroscopic unit 521 includes a first spectroscopic unit 521a and a second spectroscopic unit 521b. The first spectroscopic unit 521a passes the incident light having the first wavelength (for example, 537.5 nm) or more and sends it to the second spectroscopic unit 521b. On the other hand, the first spectroscopic unit 521a reflects the incident light having a wavelength lower than the first wavelength and sends it to the photoelectric sensor 522a. The second spectroscopic unit 521b passes light having a second wavelength (for example, 650.0 nm) or higher among the incident light (that is, light having a first wavelength or higher) and sends the light to the photoelectric sensor 522c. On the other hand, the second spectroscopic unit 521b reflects the incident light having a wavelength less than the second wavelength and sends it to the photoelectric sensor 522b. The second wavelength is longer than the first wavelength. The first wavelength and the second wavelength are visible light wavelengths (wavelengths within the wavelength range of visible light). However, the first wavelength and the second wavelength are not limited to the above example. For example, the first wavelength and the second wavelength may be visible light wavelengths different from the above example.

As described above, the spectroscopic unit 521 transmits the light of the flame F to a wavelength component having a wavelength of less than the first wavelength (for example, less than 537.5 nm) and a wavelength component of the first wavelength or more and less than the second wavelength (for example, 537.5 nm or more). The wavelength component of less than 650.0 nm and the wavelength component of the second wavelength or more (for example, 650.0 nm or more) are separated.

Here, a wavelength component having a wavelength less than the first wavelength (for example, less than 537.5 nm) is referred to as a first wavelength component. A wavelength component having a first wavelength or more and less than a second wavelength (for example, 537.5 nm or more and less than 650.0 nm) is referred to as a second wavelength component. A wavelength component having a second wavelength or higher (for example, 650.0 nm or higher) is referred to as a third wavelength component. In this case, the spectroscopic unit 521 disperses the light of the flame F into the first wavelength component, the second wavelength component, and the third wavelength component. However, the spectroscopic unit 521 may disperse the light of the flame F into at least the first wavelength component and the second wavelength component. For example, the spectroscopic unit 521 may disperse the light of the flame F into four or more wavelength components.

The photoelectric sensor 522 photoelectrically converts the transmitted light and outputs an electric signal. The photoelectric sensor 522 includes, for example, a pin photodiode and the like. As described above, the first wavelength component of the light of the flame F (for example, the light of less than 537.5 nm) is sent to the photoelectric sensor 522a. The photoelectric sensor 522a photoelectrically converts the transmitted light and outputs an electric signal to the log amplifier 523a. As described above, the second wavelength component of the light of the flame F (for example, light having a diameter of 537.5 nm or more and less than 650.0 nm) is sent to the photoelectric sensor 522b. The photoelectric sensor 522b photoelectrically converts the transmitted light and outputs an electric signal to the log amplifier 523b. As described above, the third wavelength component of the light of the flame F (for example, light having a diameter of 650.0 nm or more) is sent to the photoelectric sensor 522c. The photoelectric sensor 522c photoelectrically converts the transmitted light and outputs an electric signal to the log amplifier 523c and the variable gain AC amplifier 524.

The log amplifier 523 logarithmically compresses and outputs an electric signal sent from the photoelectric sensor 522. The log amplifier 523a logarithmically compresses the electric signal sent from the photoelectric sensor 522a and outputs it to the detection unit 527. The log amplifier 523b logarithmically compresses the electric signal sent from the photoelectric sensor 522b and outputs it to the detection unit 527. The log amplifier 523c logarithmically compresses the electric signal sent from the photoelectric sensor 522c and outputs it to the detection unit 527.

The variable gain AC amplifier 524 multiplies the electric signal sent from the photoelectric sensor 522c by a predetermined gain and outputs the electric signal to the bandpass filter 525. The bandpass filter 525 extracts a predetermined frequency component from the electric signal sent from the variable gain AC amplifier 524 and outputs it to the RMS-DC converter 526. The RMS-DC converter 526 obtains the RMS value (the square root of the root mean square value of the instantaneous value) of the electric signal sent from the bandpass filter 525 and outputs it to the detection unit 527.

The detection unit 527 detects the state of the flame F by using the input electric signal. In the present embodiment, the detection unit 527 detects the presence / absence of the flame F and the temperature of the flame F.

The detection unit 527 detects the presence or absence of the flame F by using an electric signal regarding the third wavelength component of the light of the flame F (that is, the light that passes through the second spectroscopic unit 521b and is transmitted to the photoelectric sensor 522c). .. The detection unit 527 uses the electric signal output from the log amplifier 523c as an index indicating the intensity of the light of the third wavelength component (that is, an index indicating the brightness). The detection unit 527 uses the electric signal output from the RMS-DC converter 526 as an index indicating the degree of light flicker of the third wavelength component. For example, the detection unit 527 determines that the flame F exists when both the intensity of the light of the third wavelength component and the degree of the flicker of the light of the third wavelength component exceed the reference value.

The detection unit 527 has a first wavelength component (that is, light reflected by the first spectroscopic unit 521a and sent to the photoelectric sensor 522a) and a second wavelength component (that is, the second spectroscopic unit 521b) of the light of the flame F. The temperature of the flame F is detected using an electrical signal (light) that is reflected and sent to the photoelectric sensor 522b. The detection unit 527 uses the electric signal output from the log amplifier 523a as an index indicating the light intensity of the first wavelength component. The detection unit 527 uses the electric signal output from the log amplifier 523b as an index indicating the light intensity of the second wavelength component. Here, the detection unit 527 detects the temperature of the flame F by using the principle of the two-color thermometer.

FIG. 3 is an explanatory diagram for explaining the principle of the two-color thermometer. In FIG. 3, the horizontal axis is the wavelength and the vertical axis is the intensity of light, and the characteristic lines L1, L2, L3, L4, and L5 showing the characteristics of the intensity of the light emitted from the object with respect to the wavelength (hereinafter, also referred to as intensity characteristics). , L6 are shown. Between each characteristic line, the temperature of the object is different from each other. The temperature corresponding to each characteristic line increases in the order of the characteristic lines L1, L2, L3, L4, L5, and L6.

As shown in FIG. 3, in general, as the temperature of an object increases, the intensity of light emitted from the object increases. Here, focusing on the two specific wavelengths λ1 and λ2, the ratio of the intensity of the wavelength λ1 to the intensity of the wavelength λ2 is different between the characteristic lines. That is, the intensity ratio between the wavelength λ1 and the wavelength λ2 takes a unique numerical value at each temperature. Therefore, the temperature of the object can be specified from the intensity ratio of the wavelength λ1 and the wavelength λ2. The above temperature-specific principle is called the two-color thermometer principle.

Therefore, the detection unit 527 utilizes the principle of the two-color thermometer, and based on the comparison result between the intensity ratio between the first wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature, The temperature of the flame F is detected. As described above, the intensity ratio between the first wavelength component and the second wavelength component changes depending on the temperature of the flame F. The reference intensity ratio is an intensity ratio according to the temperature of the flame F, which is experimentally or theoretically assumed as the intensity ratio between the first wavelength component and the second wavelength component. The reference intensity ratio is stored in advance in a storage element or the like of the analysis device 52. For example, the analyzer 52 stores a plurality of temperatures and corresponding reference intensity ratios.

The detection unit 527 detects, for example, the temperature corresponding to the reference intensity ratio closest to the intensity ratio between the first wavelength component and the second wavelength component among the stored reference intensity ratios as the temperature of the flame F. The detection unit 527 has at least one of the intensity of the first wavelength component obtained from the electric signal output from the log amplifier 523a and the intensity of the second wavelength component obtained from the electric signal output from the log amplifier 523b. The intensity ratio may be calculated after multiplying by a correction coefficient (for example, a coefficient according to the specifications of the boiler 1). The detection unit 527 corrects a coefficient (correction coefficient) to the ratio of the intensity of the first wavelength component obtained from the electric signal output from the log amplifier 523a to the intensity of the second wavelength component obtained from the electric signal output from the log amplifier 523b. For example, a value obtained by multiplying the coefficient according to the specifications of the boiler 1) may be used as the intensity ratio to compare with the reference intensity ratio.

As described above, in the present embodiment, the detection unit 527 of the flame F is based on the comparison result between the intensity ratio of the first wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature. Detect temperature. That is, the detection unit 527 detects the temperature of the flame F based on the intensity ratio of the first wavelength component and the second wavelength component by using the principle of the two-color thermometer. Thereby, the temperature of the flame F can be obtained as information other than the presence / absence of the flame F. Therefore, the state of the flame F can be detected in more detail. In particular, by detecting the state of the flame F formed by the burner 4 provided in the furnace 2 of the boiler 1 in more detail, the combustion in the boiler 1 can be optimized, as will be described later.

As described above, the flame detection method by the flame detection device 5 includes a step by the spectroscopic unit 521 that splits the light of the flame F into at least the first wavelength component and the second wavelength component, and the first wavelength component. It includes a step by the detection unit 527 that detects the temperature of the flame F based on the comparison result between the intensity ratio with the second wavelength component and the reference intensity ratio that changes depending on the temperature.

In particular, the first wavelength component and the second wavelength component used for detecting the temperature of the flame F are preferably visible light wavelength components. Strictly speaking, in this case, the first wavelength component may contain a small amount of a short wavelength component such as ultraviolet light. As in the above example, when the first wavelength component is visible light such as light of less than 537.5 nm and the second wavelength component is visible light such as light of 537.5 nm or more and less than 650.0 nm, 2 The temperature of the flame F can be detected accurately by using the principle of the color thermometer. For example, when at least one of the first wavelength component and the second wavelength component is the wavelength component of infrared light, the electric signal indicating the first wavelength component or the second wavelength component contains excessively much noise. The accuracy of temperature detection using the principle of a two-color thermometer is reduced. For example, when at least one of the first wavelength component and the second wavelength component is the wavelength component of ultraviolet light, the magnitude of the electric signal indicating the first wavelength component or the second wavelength component becomes excessively small, 2 The accuracy of temperature detection using the principle of the color thermometer is reduced.

Here, as described above, the control device 6 controls the combustion of the burner 4 of the boiler 1 based on the temperature of the flame F detected by the detection unit 527. For example, the control device 6 controls the operation of the air supply mechanism that supplies air to the burner 4 based on the temperature of the flame F. Thereby, the amount of air supplied to the burner 4 can be controlled based on the temperature of the flame F. For example, when the boiler 1 is provided with a swirling flow forming device that forms a swirling flow of air around the central axis of the burner 4 in the vicinity of the fuel injection port of the burner 4, the control device 6 flames the operation of the swirling flow forming device. It is controlled based on the temperature of F. Thereby, the strength of the swirling flow of air in the vicinity of the fuel injection port of the burner 4 can be controlled based on the temperature of the flame F.

As described above, by controlling the combustion of the burner 4 of the boiler 1 based on the temperature of the flame F detected by the detection unit 527, the combustion in the boiler 1 can be controlled more appropriately.

As described above, in the combustion control method by the control device 6, in addition to each step of the flame detection method by the flame detection device 5, the boiler 1 is based on the temperature of the flame F detected by the detection unit 527. Further includes a step by the control device 6 for controlling the combustion of the burner 4.

Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. Will be done.

In the above, an example in which the state of the flame F formed by the burner 4 provided in the furnace 2 of the boiler 1 is detected by the flame detection device 5 has been described. However, the detection target of the flame detection device 5 may be a flame generated by equipment other than the boiler 1. That is, the flame detection device 5 may be provided in equipment other than the boiler 1.

In the above, an example in which the first wavelength component is visible light such as light of less than 537.5 nm and the second wavelength component is visible light such as light of 537.5 nm or more and less than 650.0 nm has been mainly described. However, as described above, the first wavelength and the second wavelength are not limited to the above example. That is, the wavelength ranges of the first wavelength component and the second wavelength component may be different from the above example.

1 Boiler 2 Furnace 4 Burner 5 Flame detector 6 Control device 521 Spectroscopy 521a First spectroscope 521b Second spectroscope 527 Detection unit F Flame

Claims (8)

A spectroscopic unit that splits the light of the flame into at least the first wavelength component and the second wavelength component,
A detection unit that detects the temperature of the flame based on the result of comparison between the intensity ratio of the first wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature.
To prepare
Flame detector. The first wavelength component and the second wavelength component are wavelength components of visible light.
The flame detection device according to claim 1. The flame is formed by a burner provided in the furnace of the boiler.
The flame detection device according to claim 1 or 2. With a furnace
The burner installed in the furnace and
The spectroscopic unit that splits the light of the flame formed by the burner into at least the first wavelength component and the second wavelength component, the intensity ratio between the first wavelength component and the second wavelength component, and changes depending on the temperature. A flame detection device having a detection unit for detecting the temperature of the flame based on the comparison result with the reference intensity ratio to be used.
A control device that controls the combustion of the burner based on the temperature of the flame detected by the detection unit, and
To prepare
boiler. The step of splitting the light of the flame into at least the first wavelength component and the second wavelength component,
A step of detecting the temperature of the flame based on the result of comparison between the intensity ratio of the first wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature.
including,
Flame detection method. The first wavelength component and the second wavelength component are wavelength components of visible light.
The flame detection method according to claim 5. The flame is formed by a burner provided in the furnace of the boiler.
The flame detection method according to claim 5 or 6. A step of splitting the light of the flame formed by the burner provided in the furnace of the boiler into at least the first wavelength component and the second wavelength component.
A step of detecting the temperature of the flame based on the result of comparison between the intensity ratio of the first wavelength component and the second wavelength component and the reference intensity ratio that changes depending on the temperature.
A step of controlling the combustion of the burner based on the detected temperature of the flame, and
including,
Combustion control method.

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