JPH10300075A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion device having means in which a combustion state can be detected in a stable manner even if silicon oxide is formed at the surface of an electrode means or the surface of a burner head and at the same time it can make a positive adaptation against combustion with a lack of oxygen. SOLUTION: This combustion device is comprises of a first potential sensing means 20 and a second potential sensing means 21. A flame impedance between the first potential sensing means 20 and the second potential sensing means 21 is applied and as the flame is moved away from a burner head 2, the flame impedance is increased in a monotonous manner, so that a stable operation can be assured against influence of adhesion of silicon oxide and at the same time an accurate treatment of oxygen-short combustion can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a combustion apparatus for burning fuel and a method for evaluating a flame.

[0002]

2. Description of the Related Art Conventionally, this type of combustion apparatus is disclosed in
No. 01834 and JP-A-6-213432 are generally used. These devices used a frame rod 1 and a burner head 2 as shown in FIG. The frame rod 1 has a groove 1a formed on the surface of the electrode as shown in FIG. 12 (a), or an auxiliary rod 1b at the tip of the electrode as shown in FIG. 12 (b). Processing such as welding was performed. The fuel is vaporized by the heater 4 in the vaporization cylinder 3, is ejected from the nozzle 5, is mixed with air at the same time, passes through the inside of the burner head 2, ignites when passing through the plurality of flame holes 6, and ignites the flame 7. Form. The frame rod 1 was mounted on a fixed base 10 by a mounting bracket 9 via an insulator 8 made of ceramic, and the tip was arranged so as to contact the flame 7.
Further, a DC voltage power supply and a current detecting means 1
As 2, the ammeter was connected. The ignition is performed by an ignition means 13. For example, the ignition rod 14 is attached to the fixed base 10 by a mounting bracket 16 via an insulator 15 made of ceramic, and a high voltage is applied by an AC voltage power supply 17. In general, a spark discharge is generated between the tip of the burner and the burner head 2 to ignite.

With the above configuration, a DC current flowing when a constant DC voltage is supplied between the flame rod 1 and the burner head 2 is detected, a combustion state is determined from the current value, and combustion is controlled by the combustion control means 18. I was able to control it. In general, the combustion flame 7 contains many ions and electrons generated by thermal ionization. If a current flows when a voltage is supplied between the flame rod 1 and the burner head 2, ignition occurs. The presence or absence of the flame 7 can be detected. Further, the current greatly depends on combustion conditions such as the oxygen concentration in the combustion air, and the current decreases when incomplete combustion occurs due to a decrease in the oxygen concentration, and when the current becomes lower than a preset threshold value, the combustion control means 17
Therefore, it was judged that the combustion was incomplete, and a combustion control such as issuing a warning such as a buzzer or a lamp for promoting ventilation or forcibly stopping the combustion was performed.

[0004] By the way, even if there is an organic silicone contained in a hairdressing material or the like in the combustion air, the combustion itself is normal.
However, during this combustion, an insulating silicon oxide film is formed on the surfaces of the flame rod 1 and the burner head 2, and the current flowing between the flame rod 1 and the burner head 2 becomes apparently small, so that normal combustion is performed. Nevertheless, detection failure may occur. However, in the case where the grooves 1a are provided on the surface as shown in FIG. 12A, the dispersed organic silicone does not enter the inside of the grooves 1a, so that no silicon oxide film is formed and the current does not decrease. . Further, when an auxiliary rod 1b having a different thermal expansion coefficient from that of the frame rod 1 is welded to the distal end portion as shown in FIG. A slight change in the physical shape caused by a difference in the coefficient causes cracks or peeling of the attached silicon oxide on the surface, and that portion becomes a new conductive part, and the current does not decrease, so the combustion state is detected stably I can do that.

[0005]

However, in the conventional combustion apparatus, the above-described processing is performed on the frame rod 1 to improve the silicone resistance. However, the reduction in the current due to the formation of the silicon oxide film is reduced by the flame rod. 1 and the burner head 2 having a relatively large surface area, so that even if silicon oxide does not adhere to the frame rod 1, the electric current gradually increases due to the adhesion of silicon oxide to the bar head 2. To decline. Therefore, despite the normal combustion, there is a problem that the combustion control such as causing a detection failure and forcibly stopping the combustion is erroneously operated.

Further, the frame rod 1 and the burner head 2 on which the silicon oxide film is formed need to be replaced each time, so that there is a problem that it is not economical.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a burner head for burning fuel, electrode means for contacting charged particles generated by a flame, and a means for connecting the burner head and the electrode means. Voltage applying means for applying a voltage to the electrode, current detecting means for detecting a current flowing between the burner head and the electrode means, and a first potential for detecting the potential of charged particles between the electrode means and the burner head. Detecting means, second potential detecting means for detecting a potential different from the potential, and first potential difference detecting means for detecting a first potential difference V12 between the first potential detecting means and the second potential detecting means. A combustion apparatus wherein the flame impedance between the first potential detecting means and the second potential detecting means monotonously increases as the flame is released from the burner head surface.

The flame impedance between the first potential detecting means and the second potential detecting means is substantially constant irrespective of the presence or absence of silicon oxide on the electrode means surface or the burner head surface, that is, regardless of the magnitude of the current. It is. According to the present invention, since the flame impedance is used instead of using the current as in the related art, the combustion state can be detected without being affected by the adhesion of the silicon oxide. Further, when the flame is released from the burner head surface in the case of oxygen-deficient combustion, etc., the flame impedance between the first potential detecting means and the second potential detecting means monotonously increases, so that abnormal combustion such as oxygen-deficient combustion can be accurately performed. Can be detected. Therefore, not only can the device be operated stably against silicon oxide deposition, but also appropriate measures such as stopping the combustion can be performed against oxygen-deficient combustion.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a burner head for burning fuel, electrode means for contacting charged particles generated by a flame, and voltage applying means for applying a voltage between the burner head and the electrode means. Current detecting means for detecting a current flowing between the burner head and the electrode means, first potential detecting means for detecting the potential of charged particles between the electrode means and the burner head, and a potential different from the potential And a first potential difference detecting means for detecting a first potential difference V12 between the first potential detecting means and the second potential detecting means, wherein the flame is directed from the burner head surface. A combustion device in which the flame impedance between the first potential detecting means and the second potential detecting means monotonically increases as it is released.

Regardless of the presence or absence of silicon oxide on the surface of the electrode means and the surface of the burner head, that is, regardless of the magnitude of the current, if the combustion is normal, the first potential detecting means and the second potential detecting means are used. The flame impedance between them is constant. According to the present invention, since the flame impedance is used instead of using a current as in the related art, the influence of silicon oxide adhesion can be reduced and the combustion state can be detected. Further, as the flame is released from the burner head surface during abnormal combustion such as oxygen-deficient combustion, the flame impedance monotonously increases, so that abnormal combustion such as oxygen-deficient combustion can be accurately detected.

Further, in the combustion apparatus, when the flame is released from the burner head surface, the flame does not contact a potential surface equal to the burner head potential except for the burner head.

When the flame released from the burner head surface, except for the burner head, comes into contact with an equipotential surface equal to the burner head potential, the potential distribution between the electrode means and the burner head is affected by this equipotential surface. The flame impedance becomes smaller. This tendency is further exacerbated by greater flame release. In early oxygen starvation combustion, the flame liberates only slightly from the burner head and the flame impedance increases with decreasing oxygen concentration. However, when the oxygen concentration further decreases, the flame is released more than the burner head surface, and when it comes into contact with the equipotential surface equal to the burner head potential, the flame impedance decreases. Since then, this trend has been further exacerbated. Therefore, the flame impedance has a maximum value with respect to the oxygen concentration. This is not preferable because two oxygen concentrations correspond to a certain flame impedance. In this configuration, when the flame is released from the burner head surface, the flame does not contact the potential surface equal to the burner head potential except for the burner head, so that the flame impedance monotonously increases with the decrease in the oxygen concentration. Therefore, oxygen-deficient combustion can be accurately detected.

[0013] Further, there is provided a combustion device in which the flame holding plate is an insulator. Various burner configurations have been put to practical use,
One of them is a burner configuration in which a flame holding plate is provided around the outer periphery of the burner head. The flame holding plate, the burner head and the support for fixing them are usually made of a high heat-resistant metal such as stainless steel. In this case, they are electrically at the same potential. In such a burner configuration, when the flame is released from the burner head surface, the flame comes into contact with the burner head and the flame holding plate having a potential equal to the burner head potential. In this configuration, since the flame holding plate is made of an insulating material, the above-described problem does not occur. Therefore, a burner configuration having a flame holding plate on the outer peripheral portion of the burner head is possible.

[0014] Further, there is provided a combustion device in which a flame is formed in a vertical direction. In addition to the above-described burner configuration, there is a burner configuration in which the flame is formed in the vertical direction. In this case, since a flame holding plate is not usually required, even if the burner head and the support for fixing the burner head are made of a high heat-resistant metal, the flame will flow from the burner surface during abnormal combustion such as in the absence of oxygen. Even if released
The flame does not contact any equipotential surface equal to the burner head potential other than the burner head. Therefore, the flame impedance monotonously increases with a decrease in the oxygen concentration, and oxygen-deficient combustion can be accurately detected.

Further, there is provided second potential difference detecting means for detecting a second potential difference V2b between the second potential detecting means and the burner head, and the second flame impedance between the second potential detecting means and the burner head monotonically increases. Combustion device.

In the burner configuration in which the flame is formed in the vertical direction, the second flame impedance is substantially constant even if silicon oxide is formed on the surface of the burner head and the surface of the electrode means. On the other hand, at the time of oxygen-deficient combustion, the second flame impedance monotonously increases, so that the oxygen-deficient combustion can be accurately detected. In this configuration, the second flame impedance can be used in addition to the first flame impedance. Both the first flame impedance and the second flame impedance can operate stably with respect to silicon oxide adhesion, and can accurately detect abnormal combustion such as oxygen-deficient combustion. Therefore, by detecting combustion using these two impedances,
Even if one of the impedances is an abnormal value, for example, if the impedance becomes zero due to disconnection, combustion can be detected by the remaining impedance, so that the reliability of combustion detection can be improved.

A burner head for burning fuel;
A flame formed in a vertical direction, electrode means for contacting charged particles generated by the flame, voltage applying means for applying a voltage between the burner head and the electrode means, and a current flowing between the burner head and the electrode means. Current detecting means for detecting, first potential detecting means for detecting the potential of charged particles between the electrode means and the burner head, and second potential difference detecting the second potential difference V1b between the first potential detecting means and the burner head A combustion device comprising a detection means, wherein a second flame impedance between the first potential detection means and the burner head monotonically increases when the flame is released from the burner head surface.

As described above, in the burner configuration in which the flame is formed in the vertical direction, the second flame impedance can operate stably with respect to silicon oxide deposition and can accurately detect abnormal combustion such as oxygen-deficient combustion. It is Tori. In this configuration, since only one potential detecting means is required, the configuration can be simplified and the price can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. In addition, parts not essential to the present invention, such as the vaporizing cylinder 3, are omitted in the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a configuration of a combustion apparatus according to Embodiment 1 of the present invention. In general, when a mixed gas in which gaseous fuel is mixed with primary air having a theoretical combustion air amount or less in advance is ejected from a plurality of flame holes 6 and burned, premixed with combustible gas is very close to the flame holes 6. An internal flame 7a is formed due to the combustion reaction with the primary air, and the internal flame 7a is formed.
An outer flame 7b is formed outside of a by a combustion reaction with secondary air from the surroundings. The inner flame 7a looks bright and shining, and the outer flame 7b becomes a nearly transparent combustion flame. Inner flame 7a and outer flame 7b
Together form the entire flame 7. Charged particles (ions and electrons) are present in the flame 7. One end of the electrode means 19 contacts the charged particles generated by the flame 7,
The other end is connected to the burner head 6 via the voltage applying means 11 and the current detecting means 12. The flame 7 is composed of an inner flame 7a and an outer flame 7b. Many charged particles are present in the inner flame 7a, but charged particles are present in the outer flame 7b even if the density is small. When the number of charged particles is negligibly small, for example, when the flame 7 does not exist, that is, when combustion is stopped, (1)
Even if a voltage of 0 to 20) V is applied to the electrode means 19 and the burner head 2, almost no current flows. However, even if the electrode means 19 is arranged at a position several mm away from the internal flame 7a in a normal combustion state, a current of several μA or more flows when the above voltage is applied. This indicates that charged particles are present near the inner flame 7a and also in the outer flame 7b. The current flowing between the electrode means 19 and the burner head 2 is, for example, the current detection means 12 obtained from the voltage across the resistor having a constant resistance.
Is detected by Of course, an ammeter may be used instead of the resistor.

The first potential detecting means 20 and the second potential detecting means 21 are made of a highly heat-resistant metal body, and one end thereof is arranged at a position in contact with the charged particles. The first potential detecting means 20 and the second potential detecting means 21 are attached to a fixed base (not shown) via the insulating ceramic 8 like the electrode means 19. When a current flows between the electrode means 19 and the burner head 2, there is a potential gradient between the two and the current flows spatially and spreads.
The equipotential surface of the charged particle exists orthogonal to the direction of current flow. There is an equipotential surface that contacts each of the first potential detecting means 20 and the second potential detecting means 21. Since the first potential detecting means 20 and the second potential detecting means 21 are conductive, these potentials become the same as the contacting equipotential surface. When silicon oxide is formed on the end surface of the electrode means 19 or the surface of the burner head 2 which comes into contact with the charged particles, since the silicon oxide is insulative,
Even in a normal combustion state, the current naturally decreases.
However, if the combustion is normal even if the current decreases, there is a certain potential gradient corresponding to the current value between the electrode means 19 and the burner head 2 and there is no equipotential surface. it is obvious.

When various voltages are applied using the voltage applying means 11, the current (I _fr ) flowing between the electrode means 19 and the burner head 2 and the first potential difference (V ₁₂ ) are measured, and the current is plotted on the horizontal axis. When (I _fr ) and the first potential difference (V ₁₂ ) are plotted on the vertical axis, a straight line having a constant slope is obtained. Equipotential surface in contact with first potential detecting means 20 and second potential detecting means 2
The first flame impedance (R _12s ) between the equipotential surfaces contacting 1 is defined by this slope. This point will be described later in detail with reference to FIG.

When silicon oxide is formed on the surface of the burner head 2 or the surface of the electrode means 19, the current (I _fr ) decreases, and the first potential difference (V ₁₂ ) also decreases with the current. (1) Since the flame impedance (R ₁₂ ) is substantially constant, the combustion state can be detected stably with respect to silicon oxide adhesion.

[0024] Combustion in an oxygen-deficient state (oxygen-deficient combustion) is not preferable because the lack of oxygen itself is not preferable for health and the flame 7 is released from the surface of the burner head 2 for combustion. For this reason, when the oxygen concentration falls below a certain level, measures such as stopping the combustion are required. First flame impedance (R ₁₂ ) of the present invention
Increases monotonously as the flame 7 is released from the surface of the burner head 2, that is, as the oxygen concentration decreases, so that the oxygen-deficient combustion can be accurately detected.

(Embodiment 2) Various burner configurations have been put to practical use, and one of them is a burner configuration in which a flame holding plate is provided around the outer periphery of the burner head 2. The burner head 2 shown in FIG. 2 shows the configuration of the present invention when using this burner configuration.
The flame holding plate 24 is fixed to the support 23 at the outer periphery of the burner head 2. The burner head 2, the support 23 and the flame holding plate 24 are usually made of a high heat-resistant metal such as stainless steel. Therefore, these potentials are all the same. The flame holding plate 24 is provided to secure a wide range of combustion amount. The electrode means 19, the first potential detecting means 20, the second potential detecting means 2
1. The first potential difference detecting means 22, the voltage applying means 11, and the current detecting means 12 are arranged in the same manner as in FIG.

An oxygen-deficient combustion experiment was conducted by burning the oil fan heater of this configuration in the closed small room. Combustion amount 2360kcal
/ h, a small room with a volume of 9.95 m ³ and ventilation rate of 0.12 times / h, and a combustion volume of 710 kcal / h, a volume of 3.38
Small rooms with m ³ and ventilation rate of 0.12 times / h were used respectively. At the start of combustion, the indoor oxygen concentration is about 20.2% of the initial value.
The oxygen concentration gradually decreased from about 80 minutes in the former case to about 16% after about 80 minutes, and to about 16% after about 110 minutes in the latter case. The oxygen concentration, the current (I _fr ), and the first flame resistance (R ₁₂ ) were measured continuously during each time.

FIG. 3 shows the oxygen concentration-current (I _fr ) characteristics obtained in this measurement, and FIG. 4 shows the oxygen concentration-first flame resistance (R ₁₂ ) characteristics. As shown in FIG. 3, as the oxygen concentration decreases, the current (I _fr ) is independent of the combustion amount.
Also decreased. On the other hand, as shown in FIG. 4, the oxygen concentration dependency of the first flame resistance (R ₁₂ ) showed a different tendency depending on the amount of combustion. That is, when the combustion amount is 710 kcal / h,
The first flame resistance (R ₁₂ ) monotonically increased with decreasing oxygen concentration. However, when the combustion amount is 2380 kcal / h,
The flame resistance (R ₁₂ ) ranges from an oxygen concentration of 20.2% to about 17%.
%, But increased monotonically until the oxygen concentration decreased to about 17%.
%, It decreased on the contrary. Thus, the oxygen concentration is about 1
Since the first flame resistance (R ₁₂ ) shows the maximum value at 7%, for example, the oxygen concentration corresponding to the first flame resistance (R ₁₂ ) of 25 kΩ is about 16.5% and about 17.4%. Exists. It is not preferable that the amount of detecting the oxygen deficiency state corresponds to a plurality of oxygen concentrations. This is because the oxygen deficiency state at that time cannot specify which oxygen concentration.

The reason why the first flame resistance (R ₁₂ ) shows the maximum value when the combustion amount is high is considered as follows. When the flame 7 was observed during these oxygen-deficient combustion experiments, it was observed that the flame 7 was released from the burner head 2 as the oxygen concentration decreased, and the length of the flame 7 was increased. When the combustion amount is 2380 kcal / h, when the oxygen concentration is 20.2%, the internal flame 7a contacts only the burner head 2 and does not contact the flame holding plate 24. It extended and contacted the flame holding plate 24 when the oxygen concentration was about 17%. However, in the case of the combustion amount of 710 kcal / h, the internal flame 7a originally has a small flame volume, so that the oxygen concentration was reduced, and even if the tip portion was extended, it did not reach the flame holding plate 24. Burner head 2, support body 23 and flame stabilizing plate 24
Are made of a highly heat-resistant metal, their potentials are the same. Therefore, the reason that the first flame resistance (R12) showed the maximum value when the oxygen concentration was about 17% was that the flame 7 was separated from the burner head 2 and the potential of the burner head 2 was extended when the tip end was extended. This is caused by contact with the flame holding plate 24 having an equipotential surface equal to. When the flame 7 is released from the burner head 2, it is desirable that the flame 7, except for the burner head 2, does not come into contact with an equipotential surface equal to the potential of the burner head 2. It is preferably an object. This point will be described in detail in a third embodiment.

(Embodiment 3) FIG. 5 is a sectional view showing the structure of a combustion apparatus according to Embodiment 3 of the present invention. The burner head 2 in which the flame 7 is formed in the vertical direction is used. A mixed gas of fuel and air is supplied from the lower surface of the burner head 2, and a flame 7 is formed on the surface of the burner head 2 in a vertical direction. The burner head 7 shown in FIGS. 1 and 2 has a plurality of flame holes 6 and a plurality of flames 7 are formed in a horizontal direction. However, the burner head 2 of this embodiment has a large number of small flame holes 6 ( (Not shown) are adjacent to each other, so that they are substantially one flame hole and one flame 7. The electrode means 19, the first
The electric potential detecting means 20 and the second electric potential detecting means 21 are arranged substantially at the center of the burner head 2 and have the same action as in FIG. Further, the first potential difference detecting means 22 and the voltage applying means 1
1 and the current detecting means 12 are the same as those in FIG.

The oil fan heater of this configuration is used to burn 240
Combustion at 0 kcal / h, using a DC power supply as the voltage applying means 11, maintaining the voltage of the DC power supply at various values, and removing the electrode means 19 and the burner head 2 in a state where silicon oxide does not adhere. The voltage (V _fr ), the current (I _fr ) flowing at that time, the first potential difference (V ₁₂ ), and the second potential difference (V _2b ) were measured. The first potential difference (V ₁₂ ) was measured by short-circuiting the first potential detecting means 19 and the second potential detecting means 20 with a parallel connection circuit of a fixed resistor of 1 MΩ and a capacitor of 5 μF. In addition, the second potential detecting means 20 and the burner head 2 were also short-circuited by a parallel connection circuit of a fixed resistor of 1 MΩ and a capacitor of 5 μF. Since the measurement of the first potential difference (V ₁₂ ) involves measuring the voltage across the fixed resistor of 1 MΩ in the parallel connection circuit, it is sufficient if the input impedance of the measuring device is 10 MΩ or more. Therefore, it can be measured even with a simple voltmeter such as a tester. For example, if a voltmeter having a high input impedance of 1000 MΩ or more such as an electrometer is used as the measuring instrument, there is no problem even if it is 1 MΩ or more.

FIG. 6 shows the I _fr -V ₁₂ characteristics obtained as a result.
FIG. 7 shows the I _fr -V _2b characteristics. In these figures, the characteristics in the burner configuration of FIG. 1 are also shown for comparison. Note that the current (I _fr ) did not increase linearly with an increase in the voltage (V _fr ). This is the electrode means 19
This indicates that the impedance between the coil and the burner head 2 is not ohmic, and that the current (I _fr ) has a voltage dependency.
On the other hand, as shown in FIGS. 6 and 7, the first potential difference (V ₁₂ ) and the second potential difference (V _2b ) increased almost linearly with an increase in the current (I _fr ). Considering that the first potential difference (V ₁₂ ) is the potential difference between the equipotential surface in contact with the first potential detecting means 19 and the equipotential surface in contact with the second potential detecting means 20, as described above, A linear increase in the potential difference (V ₁₂ ) implies that there is almost ohmic between both equipotential surfaces. This is the same for the second potential difference (V _2b ).

The solid line shown in FIG. 6 is a straight line obtained by linearly regressing the I _fr -V ₁₂ characteristics. The regression equation is, for example, V ₁₂ = -0.177 + 0.0179 in the case of the configuration of FIG. *
I _fr . Also in the case of the configuration of FIG. 1, a solid line similarly obtained from the linear regression equation is shown. The same applies to FIG. The linear regression equation in FIG. 6 is generally represented by the following equation.

V ₁₂ = V ₁₂₀ + R _12d * I _fr (1) where [V ₁₂ ] = [V ₁₂₀ ] = V, [R ₁₂ ] = MΩ,
[I _fr] = μA, also the V _{1 20} first intercept potential, R _12d
Is defined as the first flame impedance. It can be said that the first flame impedance (R _12d ) corresponds to the flame impedance between the equipotential surface in contact with the first potential detecting means 19 and the equipotential surface in contact with the second potential detecting means 20.

The linear regression equation of FIG. 7 is generally represented by the following equation, similarly to equation (1). V _2b = V _2b0 + R _2bd * I _fr (2) where [V _2b ] = [V _2b0 ] = V, [R _2b ] = MΩ,
[I _fr ] = μA, and V _{2 b0} is the first intercept potential, R _2bd
Is defined as a second flame impedance. The second flame impedance (R _2bd ) can be easily obtained, as with the first flame impedance (R _12d ), by including the second potential difference detecting means (not shown). As shown in FIGS. 6 and 7 or Equation (1), the I _fr -V ₁₂ characteristic and I _{fr
Although the fr} - _V2b characteristic has a linear relationship, the straight line does not pass through the origin. Although the detailed cause is not clear, it is considered that the plasma potential of the combustion plasma is involved.

As is clear from FIGS. 6 and 7, in the configuration of FIG. 5, that is, the configuration in which the flame 7 is formed in the vertical direction, the first and second dynamic flame resistances (R _12d and R _2bd )
Both have a value that is at least three times larger than those of the configuration of FIG. The larger the both dynamic flame resistance is, the larger the current (I
_fr ) in that the change in the potential difference with respect to the change is also large, in other words, high in sensitivity to the current (I _fr ). The large bi-directional flame resistance is a unique effect of the configuration of FIG.

In the same manner as in FIGS. 3 and 4, an oil-deficient combustion experiment was conducted by burning the petroleum fan heater of this configuration (FIG. 5) in a closed small room. The combustion amount was constant at 2200 kcal / h, and a small room with a volume of 9.95 m ³ and a ventilation rate of 0.12 times / h was used. The initial value of the indoor oxygen concentration was about 20.
The oxygen concentration gradually decreased from 2%, and after about 100 minutes, the oxygen concentration decreased to about 15%. The oxygen concentration, the current (I _fr ), the first flame resistance (R ₁₂ ) and the second flame resistance (R _2b ) were measured continuously over time.

FIG. 8 shows the oxygen concentration dependence of the current (I _fr ) and the first flame resistance (R ₁₂ ) obtained in this measurement.
FIG. 9 shows the oxygen concentration dependence of the current (I _fr ) and the second flame resistance (R _2b ). As shown in FIG. 8, the current (I _fr ) decreased as the oxygen concentration decreased, as in FIG. However, although the combustion amount of 2200 kcal / h is almost the same as the case of FIG. 4 (2380 kcal / h), the first flame resistance (R ₁₂ ) is monotonous even if the oxygen concentration is reduced to about 15%. Greatly increased. The configuration in FIG. 5 differs from the configuration in FIG. 2 in that the flame stabilizing plate 24 is not required, so that an equipotential surface equal to the potential of the burner head 2 does not exist in the outer peripheral portion of the burner head 2. . Therefore, even if the flame 7 is released from the burner head 2 with a decrease in the oxygen concentration and the tip of the flame 7 extends, it cannot contact the equipotential surface equal to the potential of the burner head 2. Therefore, it is considered that the first flame resistance (R ₁₂ ) monotonously increased.

As is apparent from FIG. 9, the second flame resistance (R _2b ) showed the same tendency as the first flame resistance (R ₁₂ ) with respect to the decrease in the oxygen concentration. Note that the current (I
The data of _fr ) is the same as that of FIG. The same measurement was performed for the second flame resistance (R _2b ) in the configuration of FIG.
The same tendency as in FIG. 4 was shown. The case of the second flame resistance (R _2b ) is considered to be governed by the same phenomenon as that of the case of the first flame resistance (R ₁₂ ).

In this configuration, the second flame impedance can be used in addition to the first flame impedance. Both the first flame impedance and the second flame impedance can operate stably with respect to silicon oxide adhesion, and can accurately detect abnormal combustion such as oxygen-deficient combustion. Therefore, by detecting combustion using these two impedances, even if one of the impedances is an abnormal value, for example, even if the impedance becomes zero due to disconnection,
Since combustion can be detected by the remaining impedance, the reliability of combustion detection can be improved.

Next, the stability of the structure shown in FIG. 5 against the adhesion of silicon oxide will be described in detail. Using a petroleum fan heater having the configuration shown in FIG. 5, the amount of combustion was reduced to 2200 kc during the combustion of kerosene to which 200 ppm (weight ratio) of silicone oil was added.
al / h, the first potential difference (V ₁₂ ) between the first potential detecting means 20 and the second potential detecting means 21;
A change in the second potential difference (V _2b ) between the burner head 2 and the burner head 2 and the current flowing at that time (I _fr ) over the burning time were measured. The voltage of the voltage applying means 11 is DC 24V
(Constant).

Here, an average flame impedance (R _fr ) is defined as shown in equation (3).

R _fr = V _fr / I _fr (3) Initial values for the average flame impedance (R _fr ), the first flame impedance (R ₁₂ ), and the second flame impedance (R _2b ) FIG. 10 shows the dependence of the ratio on the elapsed time of burning.

As is apparent from FIG. 10, the average flame impedance (R _fr ) increased to about twice the initial value after about 450 minutes had elapsed due to the attachment of silicon oxide. This is equivalent to a reduction in the current (I _fr ) to about に. On the other hand, both the first flame impedance (R ₁₂ ) and the second flame impedance (R _2b ) initially decreased by about 30%, but after the same elapsed time, increased by about 20% or less with respect to the initial value. Obviously, it can operate stably against oxide deposition. The stability against silicon oxide deposition is also confirmed in the configuration of FIG. The first flame impedance (R ₁₂ ) showed the same stability as that of FIG. 10, but the second flame impedance (R _2b ) showed the result that it increased with the deposition of silicon oxide. The difference in stability of the second flame impedance (R _2b ) with respect to silicon oxide deposition in the burner configurations of FIGS. 1 and 5 is unknown in detail, but the current (I _fr ) flows in the configuration of FIG. This is considered to be due to the large effective burner surface area. Thus, the fact that the second flame impedance (R _2b ) is stable against silicon oxide deposition is a unique effect in the burner configuration of FIG.

The results for the second flame impedance (R _2b ) shown in FIGS. 9 and 10 show that the structure shown in FIG. This shows that it is possible to accurately cope with lack of combustion. That is, in the configuration of FIG.
Although two potential detecting means of the first potential detecting means 20 and the second potential detecting means 21 are used, only the first potential detecting means 20 is used, and the electric potential between the first potential detecting means 20 and the burner head 2 is increased. A second electric potential difference detecting means for detecting the second electric potential difference (V _1b ) is provided, and by using only the second flame impedance (R _1bd ) obtained according to the equation (2), it is possible to stabilize against silicon oxide adhesion. And can cope accurately with oxygen-deficient combustion. This is because the second flame impedance (R _1bd ) and the above-described second flame impedance (R _2bd ) are completely equivalent. In this case, since the configuration is simple, the cost can be reduced.

The electrode means 19 and the first potential detecting means 2
Although the shapes of the 0 and the second potential detecting means 21 are shown as linear or rod-like in the figure, for example, they may be U-shaped or L-shaped as necessary.
It is also clear that the shape may be curved, such as a letter shape.

Although the combustion using liquid fuel supplied from the fuel tank has been described, it is apparent that combustion using gaseous fuel may be used.

[0047]

As described above, according to the combustion apparatus of the present invention, the following effects can be obtained.

(1) Using the first flame impedance between equipotential surfaces contacting each of the first potential detecting means and the second potential detecting means, the first flame impedance becomes monotonous as the flame separates from the burner head. Increase
Regardless of whether silicon oxide adheres to the surface of the electrode means or the surface of the burner head, that is, regardless of the magnitude of the current, it is possible to detect the combustion state and properly cope with oxygen-deficient combustion.

(2) When the flame is released from the burner head due to oxygen-deficient combustion or the like, the flame does not contact the equipotential surface equal to the burner head potential. Increase monotonically. Therefore, it is possible to appropriately cope with oxygen-deficient combustion.

(3) In the burner configuration in which a flame holding plate is arranged around the outer periphery of the burner head, the flame holding plate is made of an insulating material, so that the first flame impedance increases as the flame separates from the burner head. Increases monotonically. Therefore, it is possible to appropriately cope with oxygen-deficient combustion.

(4) Since the flame has a burner structure formed in a vertical direction, a flame holding plate is not required. Therefore, even if the burner head and the support for fixing the burner head are made of high heat resistant metal. However, even if the flame is released from the burner surface during abnormal combustion such as oxygen-deficient combustion, the flame will
Does not contact the equipotential surface equal to the burner head potential. Therefore, the flame impedance monotonously increases with a decrease in the oxygen concentration, and oxygen-deficient combustion can be accurately detected. Further, in this burner configuration, a specific effect that both the first flame impedance and the second flame impedance are large can be obtained.

(5) Further, in a burner configuration in which the flame is formed in a vertical direction, a second potential difference detecting means for detecting a second potential difference V2b between the second potential detecting means and the burner head is provided. Since a second flame impedance between the means and the burner head can also be used, a second flame impedance can be used in addition to the first flame impedance. Both the first flame impedance and the second flame impedance can operate stably with respect to silicon oxide adhesion, and can accurately detect abnormal combustion such as oxygen-deficient combustion. Therefore, by detecting combustion using both impedances, even if one of the impedances becomes an abnormal value, for example, if the impedance becomes zero due to disconnection, the combustion can be detected with the remaining impedance, so the reliability of the combustion detection is improved. Can be improved. The fact that the second flame impedance can also operate stably against silicon oxide deposition is a unique effect of this burner configuration.

(6) Further, since only the second flame impedance (R _1bd ) which is completely equivalent to the above-described second flame impedance (R _2bd ) can be used, the configuration can be simplified and the price can be reduced. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a combustion apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a combustion apparatus according to a second embodiment of the present invention.

FIG. 3 is a graph _showing I _fr -oxygen concentration characteristics in the combustion apparatus.

FIG. 4 is a diagram _showing R _{12d -oxygen} concentration characteristics in the combustion apparatus.

FIG. 5 is a configuration diagram of a combustion device according to a third embodiment of the present invention.

FIG. 6 is a V ₁₂ -I _fr characteristic diagram of the combustion device.

FIG. 7 is a V _2b -I _fr characteristic diagram in the third embodiment.

FIG. 8 is a diagram _showing R _{12d -oxygen} concentration characteristics in the combustion apparatus.

FIG. 9 is a diagram _showing R _{2bd -oxygen} concentration characteristics in the combustion apparatus.

FIG. 10 is a graph showing the change over time of the ratio to the initial value in a kerosene combustion flame with 200 ppm silicone oil when the combustion apparatus is used.

FIG. 11 is a sectional view of a main part of a conventional combustion device.

FIG. 12A is a main part configuration diagram of a conventional combustion device. FIG. 12B is a main part configuration diagram of a conventional combustion device.

[Explanation of symbols]

 2 Burner head 7 Flame 11 Voltage applying means 12 Current detecting means 19 Electrode means 20 First potential detecting means 21 Second potential detecting means 22 First potential difference detecting means 23 Supporting body 24 Flame holding plate

Claims (6)

[Claims] A burner head for burning fuel; electrode means for contacting charged particles generated by a flame; voltage applying means for applying a voltage between said burner head and said electrode means; Current detecting means for detecting a current flowing between the electrode means, first potential detecting means for detecting the potential of charged particles between the electrode means and the burner head, and second potential detecting a potential different from the potential Detecting means, and first potential difference detecting means for detecting a first potential difference V12 between the first potential detecting means and the second potential detecting means, and the first potential difference is determined as the flame is released from the burner head surface. A combustion device in which a first flame impedance between a potential detecting means and the second potential detecting means monotonically increases. 2. The combustion apparatus according to claim 1, wherein the flame does not contact an equipotential surface equal to the burner head potential except for the burner head when the flame is released from the burner head surface. 3. The combustion device according to claim 2, wherein the flame holding plate is an insulator. 4. The combustion device according to claim 1, wherein the flame is formed in a vertical direction. 5. A second electric potential difference detecting means for detecting a second electric potential difference V2b between the second electric potential detecting means and the burner head,
The combustion apparatus according to claim 4, wherein the second flame impedance between the second potential detecting means and the burner head monotonically increases. 6. A burner head for burning fuel, a flame formed in a vertical direction, electrode means for contacting charged particles generated by the flame, and a voltage for applying a voltage between the burner head and the electrode means. Applying means, current detecting means for detecting a current flowing between the burner head and the electrode means, first potential detecting means for detecting the potential of charged particles between the electrode means and the burner head, A second electric potential difference detecting means for detecting a second electric potential difference V1b between the first electric potential detecting means and the burner head, wherein the second electric potential difference means is provided between the first electric potential detecting means and the burner head as the flame is released from the burner head surface. The combustion apparatus in which the second flame impedance monotonically increases.