JP2685100B2 - Flame detection method and flame detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flame detection method and a detection apparatus used in a combustion device such as a boiler, and more particularly to a highly reliable flame contact type flame detection method and a detection apparatus. .

[Conventional technology]

FIG. 4 is a diagram showing a configuration of a conventional flame contact type flame detection device used in a boiler ignition burner, which includes a detection electrode 19 inserted in an ignition torch, a flame resistance setting circuit 20, an amplification circuit 21, and a comparison. It is shown to consist of a circuit 22 and a display 23. The flame contact type flame detection device utilizes the fact that the flame exhibits conductivity due to ionization, and detects a change in electrical resistance between the detection electrode 19 exposed to the flame and the burner 15 electrically grounded 18. Then, the presence or absence of flame is detected. That is, the insulation resistance between the burner 15 and the detection electrode 19 when there is no flame shows a value of approximately 500 MΩ or more, but when a flame is formed, the insulation resistance between the two is several hundreds k.
By utilizing the fact that it decreases from Ω to several MΩ, it is attempted to detect this and determine the presence or absence of flame. Detection electrode
As the 19, a SiC-based ceramic material excellent in heat resistance and electric conductivity is used, and the setting position thereof is such that the flame 16 and the electrode 19 have a length of 50 so that the flame ion current can be reliably detected.
Insert it in the furnace so that it contacts over mm.

However, in this type of method, the insulation between the detection electrode 19 and the burner 15 / grounding 18 may decrease due to adhesion of unburned carbon and the value may reach several tens of MΩ. However, there was a risk of giving a false signal with a flame.

Also, when a black skirt is formed in the flame and the flame is formed at a position away from the tip of the burner,
Since the conductivity of the black skirt is extremely low, the resistance value between the detection electrode 19 and the burner 15 / ground 18 is 100-200 MΩ
Therefore, even if a flame is actually formed, it may be determined that there is no flame, and this is also a problem in terms of reliability.

[Problems to be solved by the invention]

As described above, in the conventional flame contact type flame detection device, since the deterioration of the insulation between the detection electrode and the burner / ground due to carbon adhesion, etc. was not taken into consideration, the error that there was a flame even when there was no flame There is a risk of causing a serious problem for the combustion device that the judgment is made and the fuel supply is continued, and since there is no consideration for the case where the black skirt occurs in the flame, the flame is present. However, there was a big problem in using the combustion device that it made an erroneous determination that there was no flame.

An object of the present invention is to solve the problems of the above-mentioned conventional techniques and provide a highly reliable flame detection method and detection apparatus.

[Means for solving the problem]

The purpose of the above is to detect the initial leak current for the reference applied voltage between the detection electrode and the burner / grounding before flame ignition in the flame contact type flame detection method, and set the current value to the preset reference current value or the previous ignition. And the flame ion current value at the time of ignition, and the presence or absence of flame This can be achieved by determining the ignition status.

In addition, in Japanese Patent Laid-Open No. 42-10030, a detector for detecting the combustion state of the burner for the purpose of detecting the flame of the main burner at each load change including the start-up of the boiler, and the detection of the detector A calculation unit for calculating an average value of the values within a predetermined time, a storage device for storing the output of the calculation unit, and a burner blinking signal depending on the change rate of the calculation unit output using the storage value of the storage device as a comparison reference value. Although a burner monitoring device characterized by having a determination unit that occurs, is disclosed,
The detection method in this case is not particularly specified, but is mainly intended to detect the difference in the amount of ultraviolet rays generated by the flame to determine the presence or absence of the flame in the main burner.

On the other hand, the present invention, in a flame contact type flame detector utilizing the conductivity of the flame, determines the insulation deterioration state between the flame contact electrodes, which is a problem peculiar to the detector, and forms a black skirt on the flame. The main object of the invention is to determine the combustion state in the case of the above, and the present invention and the above-mentioned known example have completely different configurations and objects.

[Action]

When the insulation deterioration between the detection electrode, the burner, and the ground progresses in the flame contact type flame detection device, the insulation resistance decreases, so that the initial leak current value with respect to the reference applied voltage in the absence of flame increases. Therefore, the insulation deterioration state can be diagnosed by comparing and calculating the detected initial leak current value and the flame ion current value or the reference current value at the time of the previous ignition. That is, for example, when 50 V is applied as the reference applied voltage, the initial leak current value when the insulation state is normal is in the range of 0.1 to 0.15 μA, but the flame ion current value in the presence of flame also includes the leak current. , 10 to 100 μA, and shows a current value that is about two orders of magnitude higher. Therefore, the detected initial leak current value and the previously stored flame ion current value at the time of the previous ignition are compared and calculated, and, for example, the initial leak current value is 0 to 50 with respect to the flame ion current value at the time of the previous ignition. If it is in the range of%, it can be judged to be almost normal, and if it is 50% or more, it can be judged to be abnormal and this result can be displayed.

Also, when a black skirt is formed on the flame, it has been experimentally confirmed that the flame ionic current value is about 0.2 to 0.5 μA because the conductivity of the black skirt is low. Therefore, the initial leak current value and the flame ion current value are compared and calculated, and the difference is about 2 to 3 times, which is relatively small, but a signal with a flame is generated even when a black skirt is formed. You can

〔Example〕

Hereinafter, the flame detecting method and the flame detecting device of the present invention will be described more specifically by way of examples.

FIG. 1 is a diagram showing a configuration in which the flame detection device of the present invention is applied to an ignition burner. The detection electrode 5, the detection electrode 5, the ignition burner 1 and the ground 4 inserted in the flame 2 of the ignition burner 1.
A current detection circuit 6 for detecting an initial leak current or a flame ion current 3 flowing between and, and a comparison calculator 7 for comparing and calculating an initial leak current value immediately before ignition and a flame ion current value or a reference current value at the previous ignition. , A flame ion current memory circuit 8, a reference current memory circuit 9, an indicator 10 for displaying a diagnosis result of insulation deterioration, a flame ion current value at the time of ignition and an initial leak current value or a reference current value are compared and operated to calculate the flame. It is shown that it comprises a comparison calculator 11 for judging the presence / absence and the combustion status and a display 12 for displaying the judgment result of the presence / absence of the flame and the combustion status.

Next, FIG. 2 is a flame detection flow chart, and FIG. 3 is a procedure for determining the insulation deterioration state between flame contact electrodes, presence / absence of flame, and flame state using the flame detection device of the present invention.
This will be described with reference to the figure detection current value pattern.

That is, first, after turning on the flame detection device monitoring command, the state of insulation deterioration between the flame contact electrodes is diagnosed. The diagnostic method is to apply a reference voltage between the detection electrode 5 and the ignition burner 1 / ground 4 to detect the initial leak current, and to determine the current value and the flame ion current value or reference current value at the time of the previous ignition. It is performed by performing a comparison operation. When the reference applied voltage is 50 V, as described above, the initial leak current value when the insulation state is normal is in the range of 0.1 to 0.15 μA, while the flame ion current value during flame formation is 10 to 10 including the leak current. Since it has reached 100 μA, and there is a difference of approximately two digits between the two, the detected initial leak current value and the previously stored flame ion current value at the time of previous ignition are compared and calculated. If it is in the range of 0 to 5% with respect to the flame ion current value at the time of the previous ignition, it is normal.
If it is within the range of 50% to 50%, be careful.If it is set to be abnormal if it shows a value of 50% or more, the insulation state between the flame contact electrodes is diagnosed and the result is displayed by a lamp or the like. Can be displayed. At the time of the first ignition operation, there is no flame ion current data at the time of the previous ignition, but the flame ion current value is 10μ on the safety side.
By storing A as the reference current value, the insulation state diagnosis can be performed by comparing and calculating this value and the initial leak current value. Further, on the basis of the above-mentioned diagnosis result, when an abnormality is shown, the ignition burner portion is disassembled, inspected and cleaned, and when a caution is shown, the ignition burner portion is inspected after the ignition operation is finished.

Next, if the insulation result is normal as a result of the above diagnosis, the ignition command of the igniter is turned on, and then the fuel valve open command is issued.
Set to ON. When the fuel valve is opened and a flame is formed by the ignition of the igniter 13, the flame ion current 3 flows between the detection electrode 5 and the ignition burner 1 / ground 4 due to the conductivity of the flame. The flame formation can be confirmed by comparing the current value with the initial leak current value. Here, even if a flame is formed, the flame ion current value greatly varies depending on the presence or absence of the black skirt, but the initial leak current value and the flame ion current value are compared and calculated, and for example, the flame ion is compared with the initial leak current value. If the current value stays in the range of 1 to 1.2 times, there is no flame, if it is in the range of 1.2 to 10 times, there is flame (but blown flame), and when it is 10 times or more, there is flame (normal flame) It is possible to set so as to determine the presence or absence of flame and the state of flame, and display the result. When the actual measurement data of the frame ion current at the time of forming the black skirt is obtained, it can be stored in the storage circuit 8 and used for the determination.

〔The invention's effect〕

As mentioned above, in flame contact type flame detection,
The following effects can be obtained by using the flame detection method and flame device of the present invention.

(1) By enabling diagnosis of the insulation state between the flame contact electrodes before flame ignition, the presence of a flame is indicated even when there is no flame due to insulation deterioration between both electrodes as in the case of the conventional technique. It has become possible to prevent the occurrence of malfunctions.

(2) With respect to the flame formed after ignition, whether or not the black skirt is formed allows the reliable determination of the existence of the flame, so that the flame is present when the black skirt is formed as in the conventional technique. However, it was possible to prevent an erroneous determination that a determination was made that there was no flame, and it was possible to greatly improve the reliability of the determination.

(3) Ignition burner Since the combustion state of the flame can be diagnosed, it can be used for setting initial conditions and maintenance of the ignition burner.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration when the flame detection device of the present invention is applied to an ignition burner, and FIG. 2 is a procedure for diagnosing an insulation state between flame contact electrodes and presence / absence of a flame by the flame detection device of the present invention. FIG. 3 is a diagram showing a pattern of a detected current value during insulation state diagnosis and flame detection, and FIG. 4 is a diagram showing a configuration when a conventional flame contact type flame detection device is applied to an ignition burner. is there. 1 ... Ignition burner, 2 ... Flame 3 ... Flame ion current 4 ... Grounding, 5 ... Detection electrode 6 ... Current detection circuit, 7 ... Comparison calculator 8 ... Flame ion current storage circuit 9 ... Reference current memory circuit, 10 …… Display unit 11 …… Comparison calculator, 12 …… Display unit 13 …… Ignator, 14 …… Combustion air 15 …… Ignition burner, 16 …… Flame 17 …… Flame ion current 18 …… Grounding, 19 …… Detecting electrode 20 …… Frame resistance setting circuit 21 …… Amplifying circuit, 22 …… Comparison circuit 23 …… Display, 24 …… Ignator 25 …… Combustion air

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-252823 (JP, A) JP 61-90051 (JP, A) JP 63-87524 (JP, A) JP 62- 5014 (JP, A) JP 62-202933 (JP, A) Actually opened 63-104838 (JP, U) Actually opened 60-181563 (JP, U)

Claims (2)

(57) [Claims] 1. A flame contact type flame detection method for determining the presence or absence of a flame based on a change in a current value with respect to a reference voltage applied between a detection electrode and a burner / ground. Between the initial leak current value and the flame ion current value or the reference current value at the time of the previous ignition are compared and the insulation deterioration state between the detection electrode and the burner / ground is judged from the calculation result. The flame ion current after formation and the initial leak current value are compared and calculated, the presence or absence of flame and the flame state are judged from the calculation result, and the above two judgment results are displayed by a lamp or an alarm. Flame detection method. 2. A flame-contact type flame detection device for determining the presence or absence of a flame based on a change in a current value with respect to a reference voltage applied between a detection electrode and a burner / ground, a detection electrode inserted into the flame of a burner, A current detection circuit that detects the initial leak current or flame ion current that flows between the detection electrode and the burner / ground, and a comparison calculator that compares the initial leak current value with the flame ion current value or reference current value at the time of the previous ignition. , Flame ion current memory circuit, reference current memory circuit, indicator for displaying insulation condition diagnosis result between detection electrode and burner / ground, comparison operation to compare and calculate flame ion current value and initial leak current value or reference current value And a display for displaying the presence / absence of flame and the judgment result of the combustion state based on the comparison calculation result of the comparison calculation unit. Flame detection device that.