JP2000018546A - Method and device for detecting amount of combustion in incinerator, method and device for controlling combustion in incinerator and incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the detection of an amount of combustion in a furnace instantaneously and correctly without being affected by the adhesion of dust, generation of smoke or the like and permit the restriction of discharge of incomplete combustion gas to the outside of a furnace by controlling the amount of air immediately based on the fluctuation of the amount of combustion. SOLUTION: An incinerator 1 is provided with acoustic wave oscillators 8, 8a, irradiating acoustic wave into a space in the incinerator 1, which includes unburnt gas, acoustic wave receivers 9, 9a, receiving the acoustic wave, and an operating means 10, operating the propagating time of the acoustic wave and detecting the amount of combustion. Further, the incinerator 1 is provided with a primary air ventilating means 3 as well as a primary air controlling means 4, ventilating the optimum amount of primary air (a1) against a matter to be incinerated 2, and a secondary air ventilating means 6 as well as a secondary air controlling means 7, ventilating the optimum amount of secondary air (a2) into the space 5 above the matter to be incinerated 2, which includes unburnt gas. In this case, the amount of primary air or secondary air is controlled based on an information from the operating means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incinerator using solid fuel such as municipal solid waste, industrial waste, RDF, and coal as a fuel. The present invention relates to a control method, an apparatus, and an incinerator.

[0002]

2. Description of the Related Art Normally, when solid fuel such as municipal solid waste, industrial waste, RDF, and coal is incinerated in an incinerator, the fuel supply fluctuates. If the fuel supply is excessive, the oxygen concentration in the combustion gas decreases, causing incomplete combustion, and if the fuel supply is insufficient, the temperature of the combustion gas decreases, causing incomplete combustion. When such incomplete combustion occurs, a large amount of harmful substances such as dioxin and carbon monoxide are released.

Therefore, it is necessary to detect the concentration of incomplete combustion gas instantaneously, adjust the air amount immediately, and perform complete combustion before the incomplete combustion gas is discharged. Therefore, focusing on the fact that the degree of brightness of the flame differs depending on the amount of combustion, a method has been proposed in which the brightness in the furnace is measured by a brightness detection sensor to control the air amount in proportion to the brightness value. (See Japanese Patent Application Laid-Open No. 6-42726).

[0004]

However, with the above-mentioned optical method, although the measurement can be performed instantaneously, there is a problem that the sensitivity cannot be accurately detected due to a decrease in sensitivity due to dust adhesion or disturbance due to light from the furnace wall. There is. Therefore, the installation place of the detector is limited to the furnace top, etc., special measures are required so that dust does not adhere, and the pressure detection sensor etc. should be used in case the inside of the furnace becomes dark due to the generation of smoke. There is also a need for juxtaposing other means. further,
Although the temperature distribution in the furnace tends to flow, even with the same amount of combustion, if the position of the flame is far away from the brightness sensor, the detected brightness will decrease, and the detection results will tend to vary widely. . As a result, the above-mentioned optical method is liable to cause a malfunction and cannot completely prevent incomplete combustion.

The present invention has been made in view of the above-mentioned problems of the prior art, and is capable of instantaneously and accurately detecting the amount of combustion in a furnace without being affected by the adhesion of dust or the generation of smoke. A method and apparatus for detecting the amount of combustion in an incinerator, in which the amount of air in the incinerator can be adjusted immediately in accordance with the fluctuations in the amount of combustion, thereby suppressing the release of incomplete combustion gas outside the furnace. And to provide an incinerator.

[0006]

The invention according to claim 1 is a method for detecting the combustion amount of an incinerator, which measures the propagation time of a sound wave passing through the incinerator, and based on the measured propagation time. It is characterized by detecting a combustion amount. The sound wave is fast, and the amount of combustion can be detected instantaneously. Also,
Unlike the optical method, it is not affected by the adhesion of dust to the sensor or the generation of smoke. In addition, the propagation time of the sound wave is detected as a result of the average propagation velocity in the propagation path, and a locally high temperature does not affect the detection result anywhere in the furnace. .

According to a second aspect of the present invention, in addition to the first aspect, the frequency of the sound wave is 1 kHz or more. If the frequency is lower than 1 kHz, the frequency of the noise is equal to the frequency of the noise of the peripheral device, so that the frequency is easily affected by the noise. lk
By setting the frequency to Hz or more, the influence of noise can be reduced, and the S / N ratio can be increased even with a small sound wave output.

According to a third aspect of the present invention, in addition to the first or second aspect, the frequency of the sound wave is 20 kHz.
z or more. 20kHz even at lkHz or more
If less, it is within the audible range. Above 20kHz
Since it is inaudible to human ears, the problem of noise can be eliminated.

According to a fourth aspect of the present invention, there is provided an apparatus for detecting the amount of combustion in an incinerator, comprising: a sound wave oscillator for emitting a sound wave into a space containing unburned gas in the combustion furnace; and a sound wave receiver for receiving the sound wave. And a calculating means for calculating a propagation time of the sound wave in the space and detecting a combustion amount. The sound wave oscillator and the sound wave receiver oscillate and receive sound waves regardless of the presence or absence of dust. Also smoke was generated,
Even if the internal state is not visible, it can be detected. Further, even if the fuel is locally burning, the propagation speed is measured as an average of the whole, so that a stable and accurate combustion amount can be detected. The sound wave is fast, and the amount of combustion can be detected instantaneously.

According to a fifth aspect of the present invention, in addition to the fourth aspect, the frequency of the sound wave is 1 kHz or more. Since it does not match the frequency of the noise made by peripheral equipment,
The influence of noise is small.

According to a sixth aspect of the present invention, in addition to the fourth or fifth aspect, the frequency of the sound wave is 20 kHz.
z or more. It does not cause noise problems because it is inaudible to human ears.

According to a seventh aspect of the present invention, there is provided a combustion control method for an incinerator, comprising measuring a propagation time of a sound wave passing through the incinerator, detecting a combustion amount based on the measured propagation time. The amount of air supplied into the incinerator is adjusted based on the detected amount of combustion. Measurement of the propagation time of the sound wave can be instantaneous, without delaying the fluctuation of the combustion amount,
The air volume can be adjusted.

The invention according to claim 8 is a combustion control device for an incinerator, which comprises: a sound wave oscillator for emitting a sound wave into a space containing unburned gas in the combustion furnace; a sound wave receiver for receiving the sound wave; A calculating unit for calculating a propagation time of the sound wave in the space to detect a combustion amount, and an adjusting unit for adjusting an air amount in the furnace based on information from the calculating unit. I do. The sound wave oscillator and the sound wave receiver oscillate and receive sound waves regardless of the presence or absence of dust. Further, even if smoke is generated and the internal state cannot be seen, it can be detected. Further, even if the fuel is locally burning, the propagation speed is measured as an average of the whole, so that a stable and accurate combustion amount can be detected. The measurement of the propagation time of the sound wave can be performed instantaneously, and the air amount can be adjusted without delaying the fluctuation of the combustion amount.

According to a ninth aspect of the present invention, in addition to the eighth aspect of the present invention, the adjusting means includes a space containing the primary air supplied toward the incinerated material or the unburned gas above the incinerated material. This adjusts the amount of secondary air supplied to the air conditioner. The amount of combustion in the fluidized bed is controlled by adjusting the amount of primary air. For example, if the amount of combustion in the fluidized bed is excessive and not all of the incomplete combustion gas is completely burned above the fluidized bed, the amount of primary air is reduced to reduce the amount of combustion in the fluidized bed, resulting in incomplete combustion. Suppress gas generation. By adjusting the amount of secondary air, the amount of complete combustion of incomplete combustion gas above the fluidized bed is controlled. For example, if the amount of incomplete combustion gas generated in the fluidized bed increases, the amount of secondary air is correspondingly increased.

According to a tenth aspect of the present invention, there is provided a primary air blowing means for blowing primary air toward an incinerated material, a primary air adjusting means for adjusting the amount of the primary air, and an unburned gas over the incinerated material. Secondary air blowing means for blowing secondary air into the space containing the secondary air adjusting means for adjusting the amount of the secondary air, a sound wave oscillator for emitting a sound wave into the space containing the unburned gas, and the sound wave And a calculating means for detecting a propagation time of the sound wave in the space containing the unburned gas, and controlling the primary air adjusting means or the secondary air adjusting means based on information from the calculating means. And a control means for performing the control. The incinerator incinerates municipal solid waste and industrial waste, and includes a stoker furnace and a rotary furnace in addition to a fluidized bed furnace. The sound wave is fast, and the amount of combustion can be detected instantaneously. Also, unlike the optical method, it is not affected by dust adhesion to the sensor, generation of smoke, and the like. Furthermore, the propagation time of the sound wave is detected as a result of the average propagation velocity in the propagation path, and a locally high temperature does not affect the detection result anywhere in the furnace. . Therefore, the attachment positions of the sound wave oscillator and the receiver are not particularly limited.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory diagram of an embodiment of the incinerator of the present invention, and FIGS. 2 and 3 are explanatory diagrams of a combustion amount detecting method and a control method of the present invention. FIG. 4 shows a temporal change of the combustion gas concentration by the control method of the present invention, and FIG. 5 shows another embodiment of the incinerator of the present invention.

The incinerator 1 shown in FIG. 1 is of a fluidized bed type, in which a wind box 21 is formed below the inside of a furnace wall 22 by a dispersion plate 20. The fluidized bed 2 containing the material and the silica sand is formed. Furnace wall 22
Is provided with a dust collector 23. The primary air adjusting means 4 and the primary air blowing means 3 are connected to the wind box 21 through a pipe 27, and the fluidized bed 2 is dispersed through a dispersion plate 20.
Is supplied with primary air a1. Fluidized bed 2 contains primary air a
1 fluidized. The primary air a1 is
It is also used as combustion air for incineration. A combustion chamber (free board) 5 above the fluidized bed 2 is a space for completely burning the combustion gas containing a large amount of unburned matter that has come out of the fluidized bed 2, and is used for complete combustion in a furnace wall 22 next to the combustion chamber 5. An air outlet 24 for feeding the secondary air to be supplied is provided. The air outlet 24 is connected to the secondary air adjusting means 7 and the secondary air blowing means 6 via a pipe 28. Further, a waste heat boiler 29 is provided in front of the exhaust port.

In FIG. 1, a hole 25 is provided in the furnace wall 22 beside the combustion chamber 5, and outside the hole 25, a sound wave which radiates a sound wave from the hole 25 toward the combustion chamber is oscillated. A sound wave oscillating means 8 provided with a vibrator 8a and a sound wave receiving means 9 provided with a microphone 9a which receives a sound wave which passes through the combustion chamber 5 and is reflected by a furnace wall 22a opposed thereto are provided. Further, the sound wave oscillation / reception means 8 and 9 are connected to the calculation / control means 10.

The calculation / control means 10 calculates the time required for the sound wave to propagate through the combustion chamber 5 based on the information from the sound wave oscillation / reception means 8 and 9, and based on the propagation time, calculates the primary time. Air adjusting means 18 and secondary air adjusting means 19
To adjust the amount of the primary air a1 and the amount of the secondary air a2.

As shown in FIG. 2, the signal generated by the sound wave oscillating means 8 generates a sound wave periodically.
Since this sound wave is received by the sound wave receiving means 9 via a predetermined path, a phase delay (τ) occurs between the transmission sound and the reception sound.
The arithmetic and control means 10 detects this phase delay (τ).

As shown in the following equation (1), the propagation velocity (A) of the sound wave is determined by the specific heat ratio (κ) depending on the gas composition, the gas constant (R), and the absolute temperature (T) of the gas. Is proportional to A = √ (κRT) (1) Since the rate of change between the specific heat ratio (κ) and the gas constant (R) is extremely small, the propagation speed (A) of the sound wave in the furnace is determined by the temperature of the combustion gas ( T). Therefore, it can be said that when the amount of combustion of the combustion gas is large, the temperature in the furnace is high, the propagation speed of the sound wave is high, and the propagation time is short. Conversely, when the combustion amount is small, the temperature is low, the propagation speed is small, and the propagation time is long. That is, the propagation time of the sound waves in the furnace is proportional to the amount of combustion (temperature) in the furnace. Therefore, a change in phase delay (τ) [time] caused by a sound wave of a certain speed passing through a predetermined path in the furnace can be recognized as a change in the amount of combustion.

In FIG. 3, the numerical values A, B, and C are such that A> B
> C, the combustion amount is small when τ> A, the combustion amount is appropriate when A ≧ τ> B, the combustion amount is large when B ≧ τ> C, and the combustion is excessive when τ ≦ C. . The calculating and controlling means 10 calculates τ based on the calculated value of the phase delay (τ).
If> A, the amount of combustion is small, so the secondary air amount is reduced. If A ≧ τ> B, proper combustion is maintained, and B ≧
When τ> C, the amount of combustion is large, so the amount of secondary air is increased. When τ ≦ C, excessive combustion occurs, and complete combustion cannot be performed only by controlling the amount of secondary air. Therefore, the amount of primary air is reduced, combustion in the fluidized bed 2 is reduced, and slow combustion is performed. To do. Thus, the oxygen concentration in the combustion gas is kept constant. As a result, the combustion is always performed in the combustion chamber 5 under the optimum air ratio, so that emission of dioxin and carbon oxide can be reduced.

FIG. 4 schematically shows changes over time in the combustion gas temperature, ultrasonic wave propagation time, secondary air amount, and combustion gas oxygen in the furnace controlled by the arithmetic and control means 10. is there. When the ultrasonic wave propagation time is long, the temperature of the combustion gas is low and the amount of combustion is small, so the amount of secondary air is reduced. When the sound wave propagation time is short, the temperature of the combustion gas is high and the amount of combustion is large, so the secondary air amount is increased. Since the propagation time of the sound wave is very fast and the amount of combustion can be detected instantaneously, the response time required to adjust the amount of secondary air is:
It turns out that it is a very short time.

As described above, according to the present invention, since the measurement is performed by the acoustic method, and the amount of air can be instantaneously adjusted without being affected by dust, it is almost constant as shown by the combustion gas oxygen concentration shown by the solid line in FIG. Is maintained. In contrast, as shown by the broken line, the oxygen concentration when the control by acoustic measurement as in the present invention is not performed is small as the combustion amount is large and large as the combustion amount is small, so that incomplete combustion occurs. Cheap. Further, in the optical measurement, the sensitivity of brightness depends on the distance of a bright spot (a place where the temperature is locally high), whereas in the acoustic measurement of the present invention, the sound wave has a speed change. However, since the propagation time is measured as a result of the average speed, even if a temperature gradient occurs along the path of the sound wave, the combustion amount is detected by the average amount in the combustion chamber. Therefore, the change in the combustion amount can be detected accurately, and the adjustment of the air amount does not malfunction.

The frequency of the sound wave used in the arithmetic and control means 10 is set to 1 to improve the S / N ratio.
It is preferable to use a frequency of kHz or higher. lkHz
By using the above sound waves, the influence of noise can be reduced. Further, in the case of a large furnace, the output of the sound wave becomes large and the problem of noise occurs. If the frequency is set to 20 kHz or more, the problem of noise can be eliminated because the sound cannot be heard by human ears.

The present invention is not limited to a fluidized bed type municipal waste incinerator as shown in FIG.
A similar effect can be obtained in a furnace or a rotary furnace. Also, the path of the sound wave is not limited to the one shown in FIG. 1 which receives the sound oscillating from one side of the furnace wall and reflected on the opposite side. For example, as shown in FIG. 5, a microphone 9a may be provided on the opposite side of the vibrator 8a, and a sound wave may be transmitted.

[0027]

As described above, according to the first and fourth aspects of the present invention, since the propagation speed of the sound wave is proportional to the temperature, the propagation time of the sound wave is measured to detect the amount of combustion in the combustion chamber. Yes, it can be measured instantaneously, and the amount of combustion can be detected without being affected by smoke or dust. In addition, since the sensitivity of the sound wave receiving means is determined by the propagation path of the sound wave, the amount of combustion is detected by the average amount in the combustion chamber, so that a malfunction due to a local temperature rise or the like can be prevented.

In the second, third, fifth and sixth aspects of the present invention, the frequency of the sound wave is set to 1 kHz or more or 20 kHz or more, so that it is hardly affected by noise, and the S / N ratio is reduced even with a small sound wave output. Can be bigger. Further, when the frequency of the sound wave is set to 20 KHz or more, the problem of noise can be eliminated because the sound cannot be heard by human ears.

According to the seventh, eighth and ninth aspects of the present invention, the amount of air to be supplied into the incinerator is adjusted based on the amount of combustion detected from the measurement of the propagation time of the sound wave. According to the detected value of the combustion amount, the air amount can be adjusted to an appropriate amount without delaying the fluctuation of the combustion amount. Therefore, emission of harmful gas to the outside of the furnace due to incomplete combustion can be suppressed.

According to the tenth aspect of the present invention, there is provided an incinerator having a configuration for supplying air toward the incinerated material and the incinerated material, a sound wave for measuring a propagation time of the sound wave in the incinerator and detecting a combustion amount. It has an oscillator, a sound wave receiver and an arithmetic means, and further has an adjusting means for adjusting the amount of air to be supplied into the incinerator, so that the amount of combustion can be detected instantaneously,
The air amount can be adjusted to an appropriate amount without delaying the fluctuation of the combustion amount. Further, even if dust adheres or smoke is generated in the furnace, the sound wave oscillator and the sound wave receiver can oscillate and receive sound waves without interference. Further, even if a portion where the combustion amount is large and the temperature is high occurs locally in the furnace, the propagation speed is captured as an average in the furnace, so that the combustion amount can be stably and accurately grasped.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of one embodiment of an incinerator of the present invention.

FIG. 2 is an explanatory diagram of a combustion amount detection method according to the present invention.

FIG. 3 is an explanatory diagram of a combustion amount detection method according to the present invention.

FIG. 4 is a diagram showing a temporal change of each element according to a combustion amount detection method for an incinerator according to the present invention.

FIG. 5 is a schematic explanatory view of another embodiment of the incinerator of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 2 Fluidized bed containing incineration material 3 Primary air blowing means 4 Primary air adjusting means 5 Combustion chamber 6 Secondary air blowing means 7 Secondary air adjusting means 8 Sound wave oscillating means 9 Sound wave receiving means 10 Calculation / control means a1 Primary Air a2 Secondary air

Claims (10)

[Claims] 1. A method for detecting a combustion amount of an incinerator, comprising: measuring a propagation time of a sound wave passing through the incinerator; and detecting a combustion amount based on the measured propagation time. 2. The method according to claim 1, wherein the frequency of the sound wave is 1 kHz or more. 3. The method according to claim 1, wherein the frequency of the sound wave is equal to or higher than 20 kHz. 4. A sound wave oscillator for emitting a sound wave into a space containing unburned gas in a combustion furnace, a sound wave receiver for receiving the sound wave, and a propagation time of the sound wave in the space is calculated to detect a combustion amount. A combustion amount detection device for an incinerator, comprising a calculation means for performing the calculation. 5. The incinerator combustion amount detection device according to claim 4, wherein the frequency of the sound wave is 1 kHz or more. 6. The combustion amount detection device for a combustion furnace according to claim 4, wherein the frequency of the sound wave is 20 kHz or more. 7. A method for measuring a propagation time of a sound wave passing through an incinerator, detecting a combustion amount based on the measured propagation time,
A combustion control method for a combustion furnace, comprising: adjusting an amount of air supplied into an incinerator based on the detected combustion amount. 8. A sound wave oscillator for injecting a sound wave into a space containing unburned gas in a combustion furnace, a sound wave receiver for receiving the sound wave, and calculating a propagation time of the sound wave in the space to detect a combustion amount. A combustion control apparatus for an incinerator, comprising: an arithmetic unit for performing the adjustment, and an adjusting unit for adjusting the amount of air in the furnace based on information from the arithmetic unit. 9. The adjusting means for adjusting the amount of primary air supplied to the incineration material or the amount of secondary air supplied to a space containing unburned gas above the incineration material. Item 10. A combustion control device for an incinerator according to Item 8. 10. A primary air blowing means for blowing primary air toward an incinerated material, a primary air adjusting means for adjusting an amount of the primary air, and a secondary air in a space above the incinerated material containing unburned gas. Air blowing means for blowing air, secondary air adjusting means for adjusting the amount of the secondary air, a sound wave oscillator for emitting a sound wave into a space containing the unburned gas, and a sound wave receiver for receiving the sound wave Computing means for detecting the propagation time of the sound wave in the space containing the unburned gas, and control means for controlling the primary air regulating means or the secondary air regulating means based on information from the computing means. An incinerator characterized by becoming.