JP2842264B2 - Calibration method of air flow detector in combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating an air flow detector for detecting a supply state of air in a combustion apparatus such as a boiler or an incinerator to which combustion air is supplied by a blower. It is about.

[0002]

2. Description of the Related Art For example, in a combustion device such as a boiler or an incinerator, the amount of air for combustion is detected and the supply state of air for combustion is monitored in order to obtain stable combustion performance. That is, the operating state of the blower for supplying the combustion air, the presence or absence of a blockage in the passage of the combustion air, the operation state of the damper for adjusting the air amount, and the like.

A pressure sensor using a semiconductor may be used as a detector for detecting such an air volume. Generally, in a pressure sensor using a semiconductor,
It has a characteristic that a signal value changes in response to a change in ambient temperature (generally called a temperature drift characteristic). Therefore, in the above-described combustion device, when the ambient temperature rises due to the operation of the device or a change in climate, the above-described influence is exerted on the pressure sensor, and accurate detection is hindered. Therefore, the reliability of the control of the apparatus and the determination of the abnormality is reduced.

[0004] For example, in a boiler room or the like in which a boiler is installed, the operating temperature of the boiler or the change in the atmospheric temperature due to a change in the climate may be remarkable. From the actual value, the deterioration of the accuracy becomes more remarkable. Therefore, in such a combustion apparatus, it is necessary to use a sensor having a good temperature drift characteristic in order to ensure the accuracy of control and abnormality detection, which has led to an increase in cost.

[0005]

SUMMARY OF THE INVENTION In view of the above, the present invention relates to a blower for supplying air for combustion, and a combustion apparatus having a detector for supplying the air, the temperature drift of the detector. Prevents deterioration of detection accuracy due to characteristics,
It is intended to improve the control of the combustion device and the accuracy of abnormality detection.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and comprises a blower for supplying air for combustion and an air flow detector for detecting a supply state of air from the blower. A method for calibrating an air volume detector in a combustion device, comprising: calibrating a detection value of the air volume detector when the operation of the blower is stopped to a signal value corresponding to a state where no air is supplied. Is what you do.

[0007]

According to the present invention, the combustion device (1) is a blower (6)
Combustion while receiving the supply of combustion air from. At this time, the output signal value of the air volume detector (8) is affected by the heat of the combustion device (1). After operating the combustion device (1) for the desired time, the blower (6)
Stops. Therefore, the detection value from the air volume detector (8) at this time is calibrated to a signal value corresponding to a state where no air is supplied. Hereinafter, during the operation of the combustion device (1), this adjustment is performed every time after the blower (6) is stopped.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment in which the present invention is applied to a boiler will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a specific embodiment of the present invention.

In the drawings, a combustion device (1) includes a boiler
(2) It is installed on the upper part. This combustion device (1)
It has a fuel pipe (3) and a wind box (4) as a supply path for combustion air. A fuel valve (5) is connected to the fuel pipe (3) on the way, and the wind box (4)
Has a blower (6) connected to its upstream end. Fuel valve
(5) and the blower (6) are controlled by a well-known combustion control device (7). The wind box (4) is provided with the above-mentioned air flow detector (8), and its output is
Connected as input to (9).

[0010] Here, the combustion control device in this embodiment.
(7) will be described. First, when the boiler starts operating, the combustion control device (7)
Start (6) and purge the furnace (prepurge). After the prepurge operation for a predetermined time, the fuel valve (5) is opened to start supplying fuel. This fuel is ignited by an ignition device (not shown), and actual combustion is started. And boiler
When the combustion device (1) is temporarily stopped and put into a standby state when the required load on (2) decreases, or when the operation of the boiler (2) is stopped after the operation for a desired time, First, the fire is extinguished by closing the fuel valve (5) and stopping the supply of fuel, and then the blower (6) is operated as it is to scavenge the exhaust gas after combustion from the furnace (post-purge). .
After performing this post-purge operation for a predetermined time, the blower (6)
To stop. During the combustion operation, the amount of air and the amount of fuel may be controlled to adjust the amount of combustion. For example, there are methods for adjusting the air volume, such as a method of providing an air volume adjustment damper downstream of the blower (6), and a method of controlling the number of revolutions of the blower (6) by an inverter, etc. A method of selectively opening and closing the fuel valve (5) of each fuel pipe (3) by providing (3) in parallel, and using a control valve of a type that can adjust the flow rate to an appropriate amount as the fuel valve (5) There are methods.

Since the present invention calibrates the detection value of the air flow detector (8) when the blower (6) is stopped to a signal value corresponding to a state where no air is supplied, the calibration circuit (9) )
Receives the signal of the operating state of the blower (6) from the combustion control device (7) in order to determine when to perform the calibration process, that is, the stopped state of the blower (6). vessel
The signal output of (8) is output to the combustion control device (7).

In the above configuration, when the boiler (2) is started, the combustion control device (7) starts the blower (6) to perform a prepurge operation as described above, and then opens the fuel valve (5). To start the actual combustion. During the pre-purge operation and the combustion operation, the air flow detector (8) monitors the supply state of the combustion air from the blower (6), and detects the detection signal and outputs the detection signal to the calibration circuit (9).
To the combustion control device (7) via Here, in the combustion state, since the air volume detector (8) is heated by the heat of the combustion device (1), an error gradually occurs in the detected value due to the temperature drift characteristic described above.

When the required load on the boiler (2) is reduced or when the operation of the boiler (2) is stopped,
The combustion control device (7) closes the fuel valve (5) to extinguish the fire, and operates the blower (6) as it is to perform post-purging for a predetermined time. And after performing post-purging for a predetermined time,
Stop the blower (6). When the blower (6) stops, the supply of combustion air to the wind box (4) stops, and the pressure becomes almost atmospheric pressure. Therefore, at this time, the calibration circuit (9) calibrates the signal value from the air volume detector (8) to a value in a state where no air is supplied, and stores this value. The blower (6) continues to rotate for a while due to the inertia of the fan even after the stop signal is output from the combustion control device (7), during which time some air is blown. Therefore, the calibration of the air flow sensor (8) by the calibration circuit (9) is performed when a predetermined time has elapsed after the output of the stop signal. The predetermined time is a time required before the blower (6) is completely stopped after the output of the stop signal is obtained by an experiment or the like in advance, and is a time longer than the required time. With the above calibration operation, the next time the combustion device (1) is operated, the combustion air supply state is monitored by the air volume detector (8) that has been accurately calibrated under the same temperature conditions as the combustion state. Control and abnormality detection can be performed with high accuracy. After that, blower (6)
Since such a calibration operation is performed every time the operation is stopped, the detection accuracy is maintained for a long time.

As described above, by constantly calibrating the air volume detectors (8), it is possible to calibrate the aging (deterioration) of the air volume detectors (8), and to correct the solid state of each air volume detector (8). The detection value can be calibrated based on the difference, and the accuracy of control and abnormality detection can be maintained over a long period of time. With this configuration, a temperature detector for temperature compensation is not required without using an expensive detector having good temperature drift characteristics and the like, and the control itself can be simplified. In the above embodiment, the air flow detector
Although (8) is directly attached to the wind box (4), in the boiler (2) as described above, the air flow detector (8) is installed at a location where the temperature change is relatively small (for example, inside the control box, etc.). ), And the air volume detector (8) and the wind box (4) are connected by a conduit to reduce the influence of the above-mentioned temperature. Is applied in the same manner, and the above-described effects can be exhibited. That is, even in the case of such a mounting structure, when the change in the ambient temperature due to the above-described cause is remarkable, the influence cannot be neglected. By calibrating (8), the accuracy of control and abnormality detection can be maintained for a long time. Further, in the above embodiment, the air volume detector (8) is calibrated after the post-purge, but may be calibrated before the pre-purge in the next combustion.

[0015]

As described above, according to the present invention, the detection value of the air flow detector when the blower is stopped is calibrated to a signal value corresponding to a state where no air is supplied. Since the output of the detector can be accurately calibrated, the supply state of the combustion air can be reliably monitored by the air flow detector, and control and abnormality detection can be performed with high accuracy. Moreover, since the air flow detector is constantly calibrated each time the combustion device is operated, the air flow detector can be selected without being affected by performance such as temperature drift performance. Further, according to the present invention, it is possible to calibrate the change (deterioration) with time of the air volume detector and to calibrate the detection value due to the individual difference of each air volume detector. Can be maintained over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a specific embodiment of the present invention.

[Explanation of symbols]

 (1) Combustion device (2) Boiler (3) Fuel piping (4) Wind box (5) Fuel valve (6) Blower (7) Combustion control device (8) Air flow detector (9) Calibration circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23N 5/24 F23N 3/00

Claims (1)

(57) [Claims] A blower for supplying air for combustion (6)
And an air volume detector (8) for detecting a supply state of air from the blower (6).
(6) A method for calibrating an air flow detector in a combustion apparatus, comprising calibrating a detection value of the air flow detector (8) when the operation is stopped to a signal value corresponding to a state where no air is supplied.