JPH10148331A - Abnormal combustion detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of a threshold value for deciding the normal/ abnormal of combustion condition in a combustion device and prevent mistaken decision by a method wherein the quantity of state, which shows the combustion state in the combustion device, is compared with a corrected quantity of state to decide whether the combustion state is normal or not. SOLUTION: The threshold value of an FR current is corrected based on a relation between a humidity and the FR(flame rod) current. In this case, when a signal, outputted from a humidity sensor 35 in accordance with the humidity of combustion atmosphere, is transmitted to an operation processing unit 27, the operation processing unit 27 obtains a humidity based on the signal outputted from the humidity sensor 35, then, operates the threshold value of the FR current value for deciding the normal/ abnormal of the combustion state by a predetermined formula employing the obtained value of humidity. When the threshold value is determined by the operation, the operation processing unit 27 decides the normal/abnormal of the combustion state of the combustion device based on the determined threshold value. When the combustion state is decided that it is abnormal, the operation processing unit 27 transmits an abnormality informing signal to a gas control unit 31 whereby the control device 31 effects the stopping or the like of the operation of combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal combustion detecting device for judging whether a combustion state in a combustion device is normal or abnormal.

[0002]

2. Description of the Related Art When an abnormal combustion state such as incomplete combustion occurs in a combustion device that burns fluid fuel such as gas, the amount of air supplied to the combustion device is increased, the amount of combustion is reduced, and the like. It is necessary to take measures promptly, and when the degree of abnormal combustion is extremely severe, it is necessary to forcibly stop the combustion operation.

[0003] Conventionally, in a combustion device for burning fluid fuel such as gas, normal combustion / abnormal combustion has been monitored by monitoring the combustion state based on output signals from sensors such as a frame rod (FR) and a thermistor. Is used. Of these, F
In the abnormal combustion detection device provided with R, ions present in the flame are collected by FR to generate an ion current (FR current), and the value of the FR current and the FR current corresponding to the CO concentration threshold value Based on the result of comparison with the value of
Determine the abnormality. That is, when the combustion state becomes abnormal, C
In addition to O, various components such as hydrocarbons and soot are generated, and some of these components are ionized in a high-temperature flame to become ions, and as a result, the FR current increases. By utilizing this phenomenon, it is possible to determine whether the combustion state is normal or abnormal.
For example, FIG. 4 is a diagram showing the relationship between the FR current and the CO concentration. In this figure, the value of the FR current corresponding to the threshold value a of the CO concentration is y, so that the FR current value is larger than y. When it becomes, it is determined that abnormal combustion has occurred,
In response to this determination result, various safety devices and the like for controlling the gas flow rate and the air flow rate are activated.

[0004]

Incidentally, the FR current value greatly changes depending on the atmospheric humidity. That is, when the air containing moisture (H2O) reaches the vicinity of the flame, H2O
Absorbs heat from the flame and dissociates into H and OH. At this time, as the amount of moisture contained in the air is larger, more heat is absorbed from the flame, and as a result, the temperature of the flame is reduced and the amount of ions in the flame is also reduced. It will fall.

However, in the conventional abnormal combustion detecting device,
Since the threshold value of the FR current is fixed to a predetermined value, if the difference between the actual humidity at the time of combustion and the humidity at the time when the threshold value of the FR current is set is large, the normal / abnormal combustion state is correctly determined. And there was a risk of erroneous determination.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an abnormal combustion detecting device capable of preventing erroneous determination by improving the reliability of a threshold value for determining the normal / abnormal combustion state in a combustion device. is there.

[0007]

An abnormal combustion detecting apparatus according to the present invention, which has been made to solve the above-mentioned problems, comprises a state quantity detecting means for detecting a state quantity indicating a combustion state in a combustion apparatus, and a flame atmosphere. Humidity detecting means for detecting the humidity of
A state amount threshold value correcting unit that corrects the state amount threshold based on the humidity detected by the humidity detecting unit; a state amount value detected by the state amount detecting unit; and a state amount threshold value correcting unit. And a combustion state determining unit that determines whether the combustion state is normal or abnormal by comparing the threshold value of the state quantity with the threshold value.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The state quantities indicating the combustion state in a combustion apparatus include, for example, the temperature of a flame,
Examples include the amount of ions in the flame, the concentration of CO generated from the flame, and the like. In the case of a water heater, for example, the temperature of water heated by a flame may be used as a state quantity indicating a combustion state. As described above, there are various state quantities indicating the combustion state. Among them, particularly in the present invention,
It is preferable to use an amount that significantly changes according to the change in the atmospheric humidity of the flame as the state quantity indicating the combustion state. Such a preferable state quantity includes, for example, the quantity of ions in the flame described above.

The operation of the abnormal combustion detecting device according to the present invention is as follows. When the combustion device is in the combustion state, the humidity detecting means detects the humidity of the atmosphere of the flame, and sends data of the detected humidity to the state quantity threshold value correcting means. The state quantity threshold value correction unit that has received the humidity data, based on the data,
The threshold value of the state quantity indicating the combustion state is corrected. The thus corrected state quantity threshold data and the state quantity data actually detected by the state quantity detection means are both sent to the combustion state determination means. The combustion state determining means determines whether the combustion state is normal or abnormal by comparing the corrected threshold value of the state quantity with the value of the actually detected state quantity.

The correction of the threshold value of the state quantity may be always performed during the combustion state, or
This may be performed only when the difference between the humidity detected by the humidity detecting means and the reference humidity (initial value, humidity at the previous correction, etc.) is equal to or greater than a predetermined value.

According to the abnormal combustion detecting device of the present invention,
Since the threshold value of the state quantity is appropriately corrected in accordance with the humidity in order to determine the normal / abnormal combustion state, it is possible to prevent erroneous determination of normal combustion / abnormal combustion due to humidity change.

In one embodiment of the present invention, the state quantity threshold value correction means calculates the humidity and the state quantity by linear approximation based on two different humidity values and a threshold value of the state quantity corresponding to each of the two humidity values. The relationship with the threshold value is determined. This makes it possible to simplify the arithmetic processing for changing the threshold value of the state quantity according to the humidity, and to simplify the hardware (microprocessor, memory, etc.) therefor, which is advantageous in terms of cost. is there.

In another aspect of the present invention, the state quantity detecting means is an ion current detecting means for detecting a magnitude of an ion current obtained by extracting ions contained in the flame with a flame rod. If you do this,
Since a frame rod conventionally used for detecting a combustion state can be used, there is no need to separately provide a special sensor or the like for detecting the CO concentration.
It is advantageous in terms of cost.

In another aspect of the present invention, the state quantity detecting means is a flame temperature detecting means including a temperature sensor for detecting the temperature of the flame. This makes it possible to use various temperature sensors conventionally used for detecting the temperature of the flame,
It is advantageous in terms of cost as in the case of the device of the above embodiment.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a combustion apparatus to which an embodiment of an abnormal combustion detection apparatus according to the present invention is applied.

The above-mentioned combustion device constitutes, for example, a combustion system of a water heater, and as shown in FIG.
, An air introduction part 3, a metal body 5, and a plurality of burners 7-1.
5, an insulating member 17, an FR 19, a resistor 23, a transformer 25, an arithmetic processing unit 27, a storage unit 29, a gas control device 31, and a humidity sensor 35.

An outside air suction fan 1 is provided at an end of the air introduction unit 3 and is driven to supply external air into the air introduction unit 3. The air introduction unit 3 introduces the air supplied from the fan 1 to the burner side as primary air for forming an air-fuel mixture with fuel gas, and separately as secondary air for supplementing oxygen. The metal body 5 is provided on an outer wall surface of the air introduction unit 3.

Each of the burners 7 to 15 has a base end connected to the metal body 5 at a predetermined interval from each other, and each air-fuel inlet (not shown) has an air inlet 3 and a gas manifold (not shown). Are provided so as to communicate with each other.

In the present embodiment, the interval 33 between the burners 7 to 15 is such that when at least the burners 7 to 15 are burning normally, the flames 21 do not contact each other and
The distance is set such that the degree of contact between the flames 21 increases as the flame width increases with an increase in the concentration value (transition to an abnormal combustion state). This distance is 7 to each burner
Although the size of the flame 21 blown out of the burner 15 differs depending on the size of the flame 21 (the size of the flame is affected by the structure of the burner and the type of gas used as the fuel gas), it cannot be uniquely determined. At 15, it is set as long as the fire does not deteriorate. Further, each of the above installation intervals 3
The secondary air introduction holes 41 necessary for introducing secondary air for oxygen supply to the respective burners 7 to 15 are formed in the portions of the air introduction part 3 and the metal body 5 respectively corresponding to 3. I have.

FR19 is an insulating member 1 for detecting a flame.
7 and faces the flame outlets of the burners 7 and 9. The resistor 23 and the transformer 25 are provided to form a closed loop for passing the FR current together with the FR 19, the burners 7, 9, and the metal body 5 through the flame 21 blown out from the burners 7, 9.

The storage unit 29 contains a program that defines the processing operation of the arithmetic processing unit 27.
Stores various data necessary to determine the normal / abnormal state of combustion in the combustion device.

The humidity sensor 35 is installed near the outside air suction fan 1 inside the combustion device to measure the humidity of the air supplied to the flame 21.

FIGS. 2 and 3 are diagrams showing, among various data stored in the storage unit 29, data necessary for the arithmetic processing unit 27 to determine whether the combustion state of the combustion device is normal or abnormal. is there.

FIG. 2 is a diagram showing the relationship between the value of the FR current and the CO concentration for two different humidities x1 and x2. Among the data obtained from this figure, the data at the time when the combustion device was shipped from the factory and installed at the user include the above-mentioned humidity x1 and x2, and the FR at the humidity x1%.
The threshold value y1 of the current and the threshold value y2 of the FR current when the humidity is x2% are stored in the storage unit 29 in advance.

In FIG. 2, when the normal / abnormal threshold value of the CO concentration is 2000 ppm, the FR current values y1 and y2 corresponding to the CO concentration of 2000 ppm are different between the case of humidity x1% and the case of x2%. Now, for example, if the threshold value of the FR current is set to y2, the combustion state is determined to be "normal" because the FR current yp2 corresponding to the point P2 below the line with the CO concentration of 2000 ppm is smaller than y2. Next, when the CO concentration (that is, the combustion state) does not change and the humidity changes from x2% to x1%, the point indicating the combustion state moves from P2 to P1. At this time, if the threshold value of the FR current is still y2, the FR current yp1 corresponding to the point P1 is larger than y2 even though the combustion state is normal, and the result of the determination is "abnormal". turn into.

Therefore, the threshold value of the FR current is corrected based on the relationship between the humidity and the FR current as shown in FIG. That is, when a signal output from the humidity sensor 35 according to the humidity of the combustion atmosphere is sent to the arithmetic processing unit 27, the arithmetic processing unit 2
7 is a humidity x based on an output signal from the humidity sensor 35.
Using this value of x, a threshold value y of the FR current value for determining whether the combustion state is normal / abnormal is calculated by the following equation.

Y = y1-((y1-y2) / (x2-x)
1)) × (xx1) where x1, x2: humidity, y1, y2: threshold.

Here, x1, x2, y1, and y2 are data previously stored in the storage unit 29 as described above.
When the threshold value y is determined by the calculation using the above equation, the calculation processing unit 27 determines whether the combustion state of the combustion device is normal or abnormal based on the value y. When it is determined that the combustion state is abnormal, the arithmetic processing unit 27 sends an abnormality notification signal to the gas control device 31, and upon receiving the signal, the gas control device 31 performs necessary operations such as forcibly stopping the combustion operation.

The configuration and effects of the embodiments of the present invention have been described in detail above. Of course, the embodiments of the present invention are not limited to the embodiments, and the present invention is not limited thereto. It goes without saying that various modifications are possible within the spirit and scope.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion device to which an embodiment of an abnormal combustion detection device according to the present invention is applied.

FIG. 2 shows the relationship between the value of the FR current and the CO concentration.
FIG. 4 is a diagram illustrating two humidities x1 and x2.

FIG. 3 is a diagram showing a relationship between humidity and FR current.

FIG. 4 is a diagram showing a relationship between an FR current value and a CO concentration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 5 ... Metal body 7, 9, 11, 13, 15 ... Burner 17 ... Insulating member 19 ... Frame rod (FR) 21 ... Flame 23 ... Resistance 25 ... Transformer 27 ... Arithmetic processing unit 29 ... Storage unit 31 ... Gas control device 35 ... humidity sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeo Yoshida 43-1, Uozakihama-cho, Higashinada-ku, Kobe Within Nippon Euro Co., Ltd. (72) Inventor Hiroshi Munemura 43-1 Uozakihama-cho, Higashinada-ku, Kobe Nippon Yu Within Pro Co., Ltd. (72) Inventor Yasuaki Baba No. 43-1, Uozakihama-cho, Higashi-Nada-ku, Kobe Within Japan Pro Co., Ltd.

Claims (4)

[Claims] 1. A state quantity detecting means for detecting a state quantity indicating a combustion state in a combustion device; a humidity detecting means for detecting a humidity of an atmosphere of a flame; and the state based on the humidity detected by the humidity detecting means. A state quantity threshold value correcting means for correcting the quantity threshold value; and comparing the value of the state quantity detected by the state quantity detecting means with the threshold value of the state quantity corrected by the state quantity threshold value correcting means. An abnormal combustion detection device comprising: combustion state determination means for determining whether the state is normal or abnormal. 2. The abnormal combustion detection device according to claim 1, wherein the state quantity threshold value correcting means is a linear approximation based on two different humidity values and a state quantity threshold value corresponding to each of the two humidity values. An abnormal combustion detection device, wherein a relationship between humidity and a threshold value of a state quantity is obtained by the following method. 3. An abnormal combustion detecting apparatus according to claim 1, wherein said state quantity detecting means detects a magnitude of an ionic current obtained by extracting ions contained in the flame with a flame rod. An abnormal combustion detection device characterized by being means. 4. The abnormal combustion detecting device according to claim 1, wherein the state quantity detecting means is a flame temperature detecting means including a temperature sensor for detecting a temperature of the flame. Abnormal combustion detection device.