JPH0560323A - Detecting circuit for filter clogging in combustion device - Google Patents

Abstract

PURPOSE:To detect clogging of a filter mounted on an air path to a burner to issue an alarm before a safety device of a combustion device is activated. CONSTITUTION:A fuel pump that feeds fuel to a burner 1, a fan that supplies air to the burner through an air duel, and a flame detecting electrode 4 located in a flame of the burner 1 are provided. The flame detecting electrode 4 is connected to a flame electric current detecting circuit 5 to form a safety circuit which stops burner 1 when the flame electric current detected by the flame electric current detecting circuit 5 is below the predetermined reference value. A filter-clogging detector circuit 9 compares the flame electric current of the flame electric current detecting circuit 5 with a set value a little higher than the reference value and increases the rotation speed of the fan when the flame electric current becomes lower than the set value. At this time, when the flame electric current is kept below the set value without fluctuations, an alarm 10 is activated to alert operators to clogging of the filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a filter, which is provided on the air supply side of a combustor, during combustion of a burner.

[0002]

2. Description of the Related Art A filter is attached to a flow path for supplying combustion air to a burner so that foreign matters cannot be sent to the burner together with air. This filter is mainly for the purpose of preventing the invasion of dust, a relatively fine mesh is used, and a warning sign to clean it once a week is clearly shown on the frame of the combustor.

If the combustion is continued without cleaning the filter, the air becomes insufficient and the burner causes abnormal combustion, and the safety device detects this and stops the combustion. In many cases, when the safety device is activated, an error number is displayed, and one of several check items corresponding to the error number includes checking the filter.

[0004]

By the way, the clogging of the filter largely changes depending on the environment in which the combustor is used, and sometimes the trouble does not occur even if the filter is used for a considerably long time. In addition, there are things that cannot be inspected without removing the filter, such as a supply / exhaust type combustor, and there are cases where the filter is attached to the back of the combustor and it is not usually noticeable, so periodic cleaning of the filter is not always performed. There were many cases where I suddenly noticed it by the activation of the burner safety device.

[0005]

SUMMARY OF THE INVENTION The present invention detects the clogging of a filter by utilizing the combustion characteristics corresponding to the combustion air amount of a burner. The fuel pump 2 supplies fuel to the burner 1 and the burner 1. And a flame detection electrode 4 positioned in the combustion flame of the burner 1,
When the flame current detected by the flame current detection circuit 5 connected to the flame detection electrode 4 is lower than a preset reference value, the burner stop circuit 6 causes the burner 1 to be stopped in the air passage 7 of the blower 3 in the combustor. A filter, that is, a detection circuit 9 for comparing the frame current with a set value determined separately from the reference value for mounting the filter 8 and directly stopping the burner 1 is provided. When it becomes lower than the set value, the filter detection circuit 9 increases the rotation speed of the blower 3, and when the flame current is kept lower than the set value, the alarm 10 is activated.

Further, the filter, that is, the detection circuit 9 has a timer circuit 11 so that the air flow rate changed when the frame current becomes lower than a set value is returned to a normal state after a fixed time, and the burner 1 causes the frame current to flow. Is kept lower than the set value.

Further, in order to cope with continuous use for a long time, the filter or detection circuit 9 has a timer circuit 11, and the filter or detection circuit 9 compares the set value with the frame current. Is performed at regular intervals.

[OOO8]

When fuel and air are sent to the burner 1 by the fuel pump 2 and the blower 3 to start combustion, the combustion flame is burned by the burner 1.
Formed on top. And during this combustion flame, the flame detection electrode 4
Can be attached to allow a flame current to flow between the burner 1 and the flame detection electrode 4 through the combustion flame.

Therefore, the size of the combustion flame can be known by monitoring the flame current, and even if the flame becomes too large with respect to the flame current obtained during normal combustion, the flame becomes smaller on the contrary. Since the flame current also decreases, a reference value is set in advance, and when the flame current is lower than this reference value, it is determined that the combustion is abnormal and the burner stop circuit 6 stops the burner 1.

A filter 8 attached to the air passage 7 of the blower
If the clogs occur, the combustion air becomes insufficient and the combustion flame extends, resulting in a combustion state. Further, the cause of the abnormal combustion in which the combustion flame extends in this manner is also present other than the clogging of the filter 8. Therefore, it cannot be determined that the flame 8 is clogged because the flame current is decreased by the standing flame.

According to the present invention, a filter, that is, a detection circuit 9 for comparing a preset value determined separately from the reference value of the flame current determined as abnormal combustion with a flame current is provided, and when the flame current becomes lower than the preset value. The rotation speed of the blower 3 is increased.

If the filter 8 is clogged, the flow rate resistance is large even if the number of rotations of the blower 3 is increased, so that an increase in the amount of air cannot be expected, but if the filter 8 is not clogged, the burner 1 will be used. The amount of air sent increases, the size of the combustion flame changes, and the flame current also changes. Therefore, when the frame current is kept at the value lower than the set value without changing, it can be determined that the filter 8 is clogged.

Since the clogging of the filter 8 does not occur suddenly, the decrease in the frame current may cause troubles other than the clogging of the filter 8. In this case, if the flame current further decreases due to an increase in the amount of blown air, the reference value, which is the next comparison, is approached, and the safety device of the burner operates earlier to the safe side. Further, if the flame current increases due to the increase in the air flow rate, it can be determined that the fuel and air are well balanced and the combustion is stable, and there is no particular problem even if the change in the air flow rate is maintained.

However, if the combustion is stabilized by the increase of the blown air amount, it is considered that the combustion balance during the normal combustion is deteriorated. In order to accurately detect this abnormality, a timer circuit 11 is provided in the filter, that is, the detection circuit 9, and the air flow rate is returned after a certain period of time. Is reduced, and the safety device operates based on the reference value to detect an abnormality.

On the other hand, although the filter 8 is not clogged suddenly, it may be better to operate the detection circuit when it is used in a place where the conditions are bad for a long time. If the filter, that is, the detection circuit 9 is provided with the timer circuit 11 to control the operation timing, even if the filter 8 is used in an environment in which the filter is likely to be clogged, an alarm for the clog of the filter 8 is issued before the safety device is activated. I was able to do it.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1 is a burner, 2 is a fuel pump mounted on an oil storage tank 12, 2a is an oil feed pipe connecting the fuel pump 2 and the burner 1, and the fuel in the oil storage tank 12 is fed through the oil feed pipe 2a. Sent to burner 1.

Reference numeral 3 is a blower, 7 is an air passage to which the blower 3 is connected, and 8 is a filter attached to the air passage 7.
Communicates with the wind tunnel 7a located around the burner 1,
When the blower 3 rotates, combustion air is sent to the burner 1.

Reference numeral 13 is a preheating / ignition heater attached to the burner 1, 14 is a flame spreading plate attached above the inside of the burner 1,
Reference numeral 4 denotes a flame detection electrode whose tip is located in the vicinity of the flame spreading plate 14, and the tip of the flame detection electrode 4 is located in the combustion flame during normal combustion.

Reference numeral 5 is a flame current detection circuit connected to the output of the flame detection electrode 4, 15 is a flame current reference value storage circuit, 16 is a comparison circuit, and the comparison circuit 16 is an output of the flame current detection circuit 5 and a reference. The output of the value storage circuit 15 is compared, and an abnormal signal is output when the frame current is lower than a preset reference value. Reference numeral 6 is a burner stop circuit that operates according to an abnormal signal from the comparison circuit 16, and constitutes a safety device that stops the burner 1 when the comparison circuit 16 outputs an abnormal signal.

17 is a value slightly higher than the reference value and burner 1
A set value storage circuit for storing a set value determined separately from the reference value for stopping the output of the frame current detection circuit 5 and the set value storage circuit 17. The output is compared with the output, and when the frame current is slightly higher than the reference value and lower than the set value, the operation signal is output. Reference numeral 18 denotes a filter, that is, a blower rotation speed changing circuit that operates according to an operation signal of the detection circuit 9. The rotation speed of the blower 3 is slightly increased in response to the operation signal.

Reference numeral 10 is an alarm device which is activated by an abnormal signal of the filter, that is, the detection circuit 9. The filter, that is, detection circuit 9 operates in the frame current detection circuit 5 and the set value storage circuit 17 even after the rotation speed of the blower 3 is increased. The output is compared with the output, and when there is no fluctuation in the frame current and the frame current is kept lower than the set value, the alarm device 10 is activated.

The alarm device 10 of the embodiment has a latch circuit incorporated therein, and when the alarm signal 10 is activated by an abnormal signal, it continues to operate even if the abnormal signal disappears. Reference numeral 11 is a filter, that is, a timer circuit attached to the detection circuit 9. The timer circuit 11 is configured to repeat a relatively long OFF time and a short ON time, and
The filter or detection circuit is activated during the time.

Therefore, even if the filter, that is, the detection circuit 9 is activated by the ON signal of the timer circuit 11 and outputs a signal for increasing the air flow rate, the air flow rate is restored if the signal disappears due to the OFF signal of the timer circuit 11. ..

Further, since the timer circuit 11 sends a repeated ON / OFF signal to the filter, that is, the detection circuit 9, the filter, that is, the detection circuit 9 operates at regular intervals.

[0025]

As described above, according to the present invention, the cause of the decrease in the frame current is judged by the increase in the air flow before the safe operation due to the abnormality due to the decrease in the frame current. By associating with and, clogging of the filter 8 can be detected for the first time.

On the contrary, the fact that the combustion is stabilized by increasing the blown air amount means that the combustion state in the normal state is deteriorated. According to the present invention, since the changed rotational speed of the blower is returned to the normal value by the timer circuit 11 after a fixed time, the abnormality can be immediately detected by the safety device if the combustion state becomes worse.

Further, since the filter, that is, the detection circuit 9 is activated by the timer circuit 11 at regular intervals,
Even if it is used in a dusty place, the clogging of the filter 8 can be reliably detected before the safety device operates.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of an oil combustor equipped with the present invention.

[Explanation of symbols]

 1 burner 2 fuel pump 3 blower 4 flame detection electrode 5 flame current detection circuit 6 burner stop circuit 7 air passage 8 filter 9 filter or detection circuit 10 alarm device 11 timer circuit

Claims (3)

[Claims] 1. A fuel pump 2 for supplying fuel to a burner 1.
A blower 3 for supplying air to the burner 1 and a flame detection electrode 4 positioned in the combustion flame of the burner 1, and the flame current detected by the flame current detection circuit 5 connected to the flame detection electrode 4 is , When it is lower than the preset reference value,
In the combustor for stopping the burner 1 by the burner stop circuit 6, a filter 8 is attached to the air passage 7 of the blower 3, and a set value determined separately from a reference value for directly stopping the burner 1 and the flame current are used as a reference. A filter, that is, a detection circuit 9 for comparison prior to the comparison with the value is provided, and when the frame current becomes lower than the set value, the filter detection circuit 9 increases the rotation speed of the blower 3 so that the frame current becomes lower than the set value. The combustor filter or detection circuit that activates the alarm 10 when also held low. 2. The filter, that is, the detection circuit 9 has a timer circuit 11 so that the blown air amount changed when the frame current becomes lower than a set value is returned to normal after a fixed time, and the burner 1 has a frame current The combustor filter or detection circuit of claim 1, wherein combustion is continued below a set value. 3. The filter or detection circuit 9 has a timer circuit 11, and the filter or detection circuit 9 compares the set value with the frame current at regular time intervals. A combustor filter or detection circuit according to claim 1 or claim 2.