JPH0229932B2 - KAENDENRYUKENSHUTSUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flame current detection device that uses a flame rod to detect oxygen-deficient combustion in combustion equipment that uses gas, oil, etc. as fuel. The flame current detection device described above is intended to be realized by configuring a series closed circuit that includes other burners that are electrically insulated and that affect the flame current through interference during combustion.

In conventional flame current detection devices, the burner to which the flame rod is attached is at the same potential as the main body and other burners, or the burner to which the flame rod is attached is insulated. There was a configuration that received flame interference from the burner as it was, but the type of fuel, especially gas, has large variations in composition even for the same gas type, and there are many types, and fluctuations in the source gas pressure etc. In some cases, it was impossible to set the flame current level to detect abnormal combustion conditions during oxygen deficiency, even for the same gas type.

The present invention solves the above-mentioned conventional drawbacks by appropriately applying the influence of combustion flames of other burners.

Embodiments of the present invention will be described below based on FIGS. 1 to 4.

FIG. 1 is a block diagram of a gas combustion equipment using the flame current detection device of the present invention.
is electrically insulated from the main body of the device and from other burners 3. The signal of the combustion flame is transmitted to the first and second series closed circuit sections 4 including the first and second power sources.
and is transmitted to the drive section 6 for controlling the gas solenoid valve 5. 7 is an insulated governor for burner 2, and 8 is a variable combustion amount governor for other burners 3. In this embodiment, the other burners 3 are set at the same potential as the main body, but the object of the present invention can also be achieved even if the burners 3 are insulated like the burners 2.

Next, referring to FIG. 2, a detailed explanation of the configuration of the present invention will be given. If the flame electrical signal is replaced with a substantially equivalent circuit, a resistor 9 and a diode 10 are connected between the flame rod 1 and the burner 2 in the direction in which most of the current flows from the flame rod side to the burner. Also, connect a resistor 11 and a diode 12 from the flame rod 1 side to the burner 3 where it is not attached.
can be represented as connected. In contrast to these equivalent circuits, the first series closed circuit includes the first power supply 13, the current limiting resistor R ₁ 14, the flame current signal extraction resistor R ₃ 15, and the smoothing capacitor C ₁
16 parallel circuits, the aforementioned resistor 9, and diode 10
It is formed of. The second series closed circuit includes a second power supply 17, a resistor R ₂ 18 as an impedance element, an AC component transmission capacitor C ₂ 19,
and the resistor R ₁ 14, R ₃ 15 and capacitor C ₁
It is formed of 16 circuit parts, a flame equivalent circuit resistance 11, and a diode 12. Since the flame current signal for determining oxygen deficiency, etc. is taken out from both ends of the resistor R ₃ 15, it is natural that it is greatly influenced by the flame resistor 9 in the first series closed circuit, but the actual equipment design The influence of the second series closed circuit including the frame resistance 11 in the other burner which has been subjected to the above interference is also appropriately affected, producing the characteristics described below. The characteristics of the present invention can be obtained even if the second series closed circuit does not include the resistor R ₁ 14. The degree of influence of the second series circuit will be explained below.

Next, FIG. 3 shows the relationship between oxygen concentration and flame current in the configurations of various flame current detection devices. In the figure, a shows the characteristic in a state where the second series closed circuit configuration is completely removed, and is the flame current characteristic of only the insulated burner 2. This configuration also applies to the other burner 3.
flame interference, but the overall current level is low. b is a configuration in which the second series closed circuit is removed, but the other burners 3 are set to the same potential as burner 2, or the insulation of burner 2 is removed; This method extracts the flame effect directly as a signal. In case b, it is natural that the current level is higher overall than in case a. With such conventional characteristics, the fourth
There are some fuel types for which the tolerance range Δi _fe (Δi _fe =λ _fe2 −i _fe1 ) for setting the oxygen deficiency level described in the section of the figure cannot be achieved. Therefore, with the configuration of the present invention, the change in flame current with respect to O ₂ concentration is increased, a characteristic with a large slope as shown in FIG. 3c is obtained, and the oxygen deficiency level can be set. Here, the slope of the flame current change is determined by the flame resistances 9 and 11 and the resistance in the second series closed circuit.
It depends on the relative relationship of each absolute value of R ₂ 18. When the oxygen concentration is as high as 21%, the flame resistance 9 on the first burner side to which the flame rod is attached is particularly small, and the voltage drop occurring across the flame current detection resistor _R315 is large compared to the first series closed circuit current _i1 . Therefore, the flame current value of c does not decrease significantly compared to b. However, as the oxygen-deficient state approaches, the flame tends to become diffuse combustion, and the burners become susceptible to mutual flame interference. Moreover, in the oxygen-deficient state, both the flame resistance 9 to the first burner flame and the flame resistance 11 to interference flames with other burners have large absolute values, and the voltage generated in the flame current detection resistor R ₃ 15 is large. For the descent, the second
The contribution rate of the series closed circuit current i ₂ increases. Therefore,
If the contribution rate of the resistance 18 is appropriately given to the change value of the flame resistance 11 with respect to the oxygen concentration (for example, several tens of kilohms to several megaohms), the absolute value of the flame current will be b.
Although it is lower than the characteristics of
c can be increased. Therefore, from now on, it becomes possible to determine the oxygen deficiency and set the alarm as explained in FIG. Capacitor C ₂ 19
acts as a direct current cutter for the detection voltage of the second power supply 17, but this characteristic can be obtained even without it.

FIG. 4 explains the allowable flame current range Δi _fe when setting the oxygen deficiency level in an actual device (particularly one that uses gas as fuel). _Q1 and
Q ₂ shows the two-end characteristics of the flame current variation with respect to oxygen concentration, including the composition variation within the same gas type (for example, city gas 6B) and the source pressure variation even after passing through the governor, and Q ₁ maximum,
Q ₂ is the minimum side. In this example, the O ₂ concentration at which a certain amount of CO, CO ₂ , etc. is generated from the equipment due to oxygen-deficient combustion is 16%, and the current value of Q ₁ at that time is i _fe1 . In addition, the O ₂ concentration that can be easily reached in a few hours when using combustion equipment in an actual closed room is
It is tentatively set to 19.5%, and the O ₂ current value at this time is i _fe2 . As is clear from FIG. 4, on the maximum side of combustion, including variations in various elements, the flame current in a normal combustion state is larger than the above i _fe2 . Further, on the minimum side of combustion, the flame current in an abnormal combustion state, that is, around 16% oxygen concentration, is smaller than _ife1 . Therefore, each flame current value i _fe1 shown in the same figure
When the difference in i _fe2 , that is, Δi _fe = i _fe2 −i _fe1 , is greater than a predetermined value and is a positive value, it is possible to realize a configuration that can distinguish and detect an abnormal combustion state from a normal combustion state. It is. This is because for the same gas type, by setting the level at one point, variations in components and gas pressure can be absorbed. In case a of FIG. 3, since the overall level is low, even if Δi _fe can be obtained, the disadvantage is that the design noise margin is small. In comparison, by raising the overall current level and increasing the slope as in c of the present invention, a margin is created in Δi _fe itself.

FIG. 5 shows another embodiment of the invention using an actual circuit configuration. A commercial power source 20 is connected to the first and second power sources 1 through a transformer 21.
3,17 is being made. Reference numeral 22 denotes a rectifying diode bridge, which forms a DC power source for the control circuit 23 including the drive section 6 of the electromagnetic valve 5. The same numbers as in FIG. 2 indicate the same components.

As is clear from the above description, the flame current detection device of the present invention uses the influence of the burner flame on the side to which the flame rod is attached and the fire interference of other burners during normal combustion to increase the detection voltage. At the time of abnormal combustion, i ₂ is made small by the resistance R ₂ 18 and the flame resistance 11 in the second series circuit, and as shown in Fig. 3c, a characteristic in which the flame current changes greatly with respect to the O ₂ concentration is obtained. Therefore, it is possible to secure the flame current range Δi _fe for setting the oxygen deficiency level regardless of the type of fuel, and it can serve as a safety device when incorporated into combustion equipment.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a gas combustion equipment using a flame current detection device according to an embodiment of the present invention;
Fig. 2 is a specific circuit diagram of the present invention, Fig. 3 is a diagram showing the relationship between oxygen concentration and flame current, Fig. 4 is a characteristic diagram showing the oxygen deficiency level setting range Δi _fe , and Fig. 5 is a diagram showing the relationship between oxygen concentration and flame current. FIG. 1...Flame rod, 2...Insulated burner to which flame rod is attached, 3...Other burners, 13...First power supply, 14...Resistor for current limiting R ₁ , 15... Resistor for taking out flame current signal R ₃ , 1
6... Smoothing capacitor C ₁ , 17... Second power supply,
18...Resistance as a certain impedance element
_R2 .

Claims (1)

[Claims] 1 In combustion equipment including multiple burners, the first
A parallel circuit consisting of a power source, a current limiting resistor, a flame current signal extracting resistor, and a smoothing capacitor connected in parallel with the flame current signal extracting resistor, a flame rod as a flame current detecting element, and the main body of the device. and a first series closed circuit comprising a first burner electrically insulated from the other burners and to which the flame rod is mounted; and a second power source;
A second series closed circuit consisting of an impedance element, a parallel circuit of the current limiting resistor, the flame current signal extraction resistor, and a smoothing capacitor, the flame rod, and a burner other than the first burner. A flame current detection device characterized by: