JP2951536B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for constantly controlling the amount of air supplied to a burner used in a boiler or the like.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional combustion control apparatus. In the figure, reference numeral 1 denotes a burner, 2 a fan motor for supplying air to a burner 1, and 3 represents an amount of air supplied to the burner 1. Airflow sensor for detecting, damper 4a
Is a damper mechanism for controlling the amount of air supplied to the burner 1 in accordance with the opening degree, and 4b is a control motor for driving the damper 4a. 5 is a proportional valve for controlling the fuel supplied to the burner 1, and 6 is a proportional valve for controlling the fuel in accordance with the target combustion amount.
And an arithmetic unit that controls the rotation speed of the fan motor 2 or controls the opening of the damper 4a so that the air amount detected by the air flow sensor 3 is constant.

Next, the operation will be described. When the target combustion amount is given to the calculator 6, the calculator 6 outputs a control signal corresponding to the target combustion amount to the proportional valve 5. The proportional valve 5 thereby supplies a constant fuel to the burner 1. Next, as shown in the characteristic diagram of FIG. 9, the arithmetic unit 6 outputs a control signal or a control signal as described below so as to supply the air amount corresponding to the control signal to the burner 1. (1) A case where the amount of air is controlled by changing the electric power supplied to the fan motor 2. In this case, the damper mechanism 4 is not used. Fan motor 2
The air flow sensor 3 detects the amount of air supplied to the burner 1 and outputs it to the calculator 6. The arithmetic unit 6 increases the electric power applied to the fan motor 2 by the control signal if the air amount is smaller than the target air amount, and decreases the electric power applied to the fan motor 2 if the air amount is larger than the target air amount, and performs PID control to perform a constant air amount. To the burner 1. (2) The case where the electric power supplied to the fan motor 2 is constant and the amount of air is controlled by the opening of the damper mechanism 4. In this case, no control signal is used. As in the case of (1), the arithmetic unit 6 increases the opening degree of the damper mechanism 4 by the control signal if the air amount is smaller than the target air amount, and decreases the opening degree of the damper mechanism 4 if the air amount is larger than the target air amount. , PID
Control and supply a constant amount of air to the burner 1.

[0004]

Since the conventional combustion control device is configured as described above, the air flow sensor 3
Even if the error of the detection output of the air amount becomes large due to the aging of the air flow, there is no means for correcting this error, and if the error of the air flow sensor 3 becomes large, the air-fuel ratio becomes poor and the incomplete combustion etc. There were problems such as poor raising efficiency and danger of explosion. In particular, when the airflow sensor 3 has a structure in which a temperature measuring resistor is provided on a semiconductor thin film, there is a problem that aging and the like are likely to occur due to adhesion of dust and oil contained in the air.

The present invention has been made in order to solve the above-mentioned problems. Even if the error of the detection output of the air amount becomes large due to the aging of the flow rate detector or the like, the error is corrected and the air-fuel ratio is corrected. It is an object of the present invention to obtain a combustion control device capable of maintaining a good combustion control.

[0006]

According to a first aspect of the present invention, there is provided a combustion control apparatus for supplying an air amount so that an output of a flow rate detector becomes an initial value constant each time a burner is ignited. The rotation speed of each fan motor is stored and the average value of the rotation speeds is determined. If there is a difference between the stored initial value and the average value of the rotation speed of the fan motor, the initial value of the output of the flow rate detector is determined. The arithmetic unit corrects the values based on the initial value and the average value of the rotation speed of the fan motor in which the difference has occurred.

A combustion control device according to a second aspect of the present invention supplies an air amount so that the output of the flow detector becomes constant at an initial value every time the burner is ignited, and the opening degree of the damper at each ignition time. And the average value of the openings is obtained. If there is a difference between the stored initial value and the average value of the opening of the damper, the initial value of the output of the flow rate detector is set to the damper having the difference. And an arithmetic unit for correcting based on the initial value and the average value of the opening degree.

[0008]

The arithmetic unit according to the first aspect of the present invention controls the number of revolutions of the fan motor so that the output of the flow rate detector becomes constant at the initial value (at the time of the first ignition) every time the burner is ignited. Then, the secular change of the flow rate detector is detected by a difference between the initial value of the rotation speed of the fan motor (at the time of the first ignition) and the average value of the number of times of ignition of the fan motor. When the secular change of the flow rate detector is detected, the initial value of the output of the flow rate detector is corrected based on the initial value and the average value of the rotational speed of the fan motor which has obtained the difference. Further, each time the burner is ignited, the rotation speed of the fan motor is controlled so that the corrected initial value of the output of the flow detector becomes constant.

The arithmetic unit according to the second aspect of the invention controls the opening of the damper so that the output of the flow rate detector becomes constant at the initial value (at the time of the first ignition) every time the burner is ignited. Then, the secular change of the flow rate detector is detected by the difference between the initial value of the opening degree of the damper (at the time of the first ignition) and the average value of the multiple ignitions. When the aging of the flow detector is detected,
The initial value of the output of the flow rate detector is corrected based on the initial value and the average value of the opening degrees of the different dampers. Furthermore,
Each time the burner is ignited, the opening of the damper is controlled so that the corrected initial value of the output of the flow detector becomes constant.

[0010]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a combustion control apparatus according to an embodiment of the present invention. In FIG.
a is a combustion chamber, 1b is an exhaust port of the combustion chamber 1a, 1c is an igniter for igniting the burner 1, 2a is a fan motor for controlling the amount of air supplied to the burner 1 according to the rotation speed, and 3 is a supply to the burner 1. It is an air flow sensor (flow rate detector) for detecting the amount of air to be blown. 5 is a proportional valve for controlling the fuel supplied to the burner 1, 5a is a shut-off valve provided upstream of the proportional valve 5, 8 controls the fuel by the proportional valve 5 according to a target combustion amount, and a fan motor. This is an arithmetic unit that inputs the rotation speed signal of the fan motor 2a and controls the rotation speed of the fan motor 2a so that the air amount detected by the air flow sensor 3 is constant.

Next, the operation will be described. FIG. 2 is a characteristic diagram of the amount of air supplied to the burner 1 and the output of the air flow sensor 3, and the characteristic equation in the initial state is y = ax.
FIG. 3 shows the amount of air supplied to the burner 1 and the fan motor 2.
FIG. 6 is a characteristic diagram with respect to the number of rotations of a.
bx. However, since the exhaust gas from the combustion chamber 1a is discharged outdoors, when the wind is received at the exhaust port 1b, the rotation speed of the fan motor 2a must be increased to obtain the same amount of air as when there is no wind. Therefore, in this case, r = b _{2 in} FIG.
x is a characteristic expression. Hereinafter, a procedure for correcting an error due to aging of the air flow sensor 3 will be described with reference to the flowchart of FIG.

[0012] (1) FIG. 4 is a timing chart showing the ignition operation of the burner 1, as shown in FIG, the ignition operation after a certain amount of air x ₀ which is determined in advance during the ignition of the burner 1 Do. (2) The output of the air flow sensor 3 corresponding to the amount of air at the time of ignition and the rotation speed of the fan motor 2a when there is no influence of wind on the exhaust port 1b are stored in the computing unit 8 in advance as initial values. . That is, assuming that the air amount at the time of ignition is x ₀ , the output y ₀ of the air flow sensor 3 is stored in the computing unit 8 from FIG. 2 and the rotational speed r ₀ of the fan motor 2a is stored in the computing unit 8 from FIG. 3 (step ST1). .

[0013] (3) Then the data number i from the set to 1 (step ST2), at the start of the ignition operation of the burner 1, as shown in FIG. 4, first, so that the air quantity x _0, That is, the rotation speed of the fan motor 2a is controlled so that the output of the air flow sensor 3 becomes the initial value y _0, and the rotation speed of the fan motor 2a at this time is stored in the computing unit 8 as r ₁ , and then the ignition operation is performed. (Steps ST3 to ST3)
5). However, as shown in FIG.
The difference | r ₁ − between the rotation speed of a and r ₁ and the initial rotation speed r _0.
When r ₀ | is larger than a predetermined Δr ₀ , it is determined that there is an influence of the wind of the exhaust port 1b, and the rotation speed at this time is set to r ₁
Do not remember. Thus, the rotational speed at the start of the next ignition operation as r ₁ (step ST6). Further, the difference | r ₁ −
When r ₀ | is larger than r _max , it is determined that the air flow sensor 3 is abnormal, and the ignition operation is stopped (step ST).
7, 8). If the air-fuel ratio control can be performed only by the rotation speed of the fan motor 2a, the ideal air-fuel ratio control cannot be performed. However, the combustion may be performed without using the output of the air flow sensor 3 thereafter.

(4) Thereafter, every time the ignition operation is performed, the number of revolutions of the fan motor 2a at each ignition time is changed to r ₁ , r ₂ , r
_3, successively stored and ····· r _n (step ST9~
ST11). (5) Then, when the number of stored rotation number data becomes n,
An average value r _av of n pieces of rotation speed data is obtained. (6) The stored initial value r of the rotation speed of the fan motor 2a
₀ is compared with the average value r _av, and a difference of a certain value μ or more |
When r ₀ −r _av | ≧ μ, it is determined that the airflow sensor 3 has an error due to aging (step ST1).
2), based on the initial value r ₀ and the average value r _av of the rotation speed of the fan motor 2a, update the air amount and the output characteristic equation of the air flow sensor 3 shown in FIG. updating the initial value y ₀ of the output of the sensor 3 (step ST13~ST14).

(7) The corrected characteristic equation is as follows: y = [{y ₀ + (r _av −r ₀ ) / ab} / x ₀ ] x (7-0) This equation (7-1) is obtained as follows. First, the deviation of the air amount is determined. Since the initial characteristic equation is r = bx as shown in FIG. 3, Δx ₀ = (r _av −r ₀ ) / b (7-1) Next, the deviation of the output of the air flow sensor 3 is obtained. Since the initial characteristic equation is y = ax as shown in FIG. 2, Δy ₀ = Δx ₀ / a (7-2) Substituting equation (7-1) into equation (7-2), Δy ₀ = ( r _av −r ₀ ) / ab (7-3) On the other hand, if the corrected characteristic equation is y = a ₁ x as shown in FIG. 2, it must be corrected by Δy ₀ when the air amount is x ₀ . , Y ₀ + Δy ₀ = a ₁ x ₀ (7-4). By substituting equation (7-3) into equation (7-4), a
_{When 1} is obtained, a ₁ = {y ₀ + (r _av −r ₀ ) / ab} / x _0, whereby the corrected characteristic equation (7-0) is obtained.

(8) The output y ₀₁ of the air flow sensor 3 at the time of ignition after error correction due to aging shown in FIG. 2 is obtained by substituting x ₀ into the equation (7-0), and y ₀₁ = y ₀ + (R _av -r ₀ ) / ab. The output y ₀₁ of the airflow sensor 3 after this correction
Is updated to the initial value y ₀ , and the storage of the computing unit 8 is updated. (9) Thereafter, when performing the ignition of the burner 1, the output of the air flow sensor 3 controls the fan motor 2a such that the initial value y _0, which is the updated (return to step ST3).

As described above, in this embodiment, since the air flow sensor 3 has a function of correcting even if a detection error occurs due to aging, the ideal air-fuel ratio control of the burner 1 can be always performed, and the CO And NOx generation can be suppressed below a certain value. Further, when a failure occurs in the air flow sensor 3, it can be detected before ignition in step 7 of FIG. Furthermore, even if the air flow sensor 3 fails, combustion can be performed without the air flow sensor 3.

Embodiment 2 FIG. FIG. 6 is a block diagram showing a combustion control apparatus according to one embodiment of the second aspect of the present invention. In the first embodiment, the target air amount is obtained by controlling the rotation speed of the fan motor 2a, but in this embodiment, the target air amount is obtained by controlling the opening degree of the damper 9a. Things. In the figure, reference numeral 2 denotes a fan motor which is supplied with a constant power and is controlled at a constant rotation speed, and 9 denotes a damper 9.
A damper mechanism for controlling the amount of air supplied to the burner 1 in accordance with the opening degree of a, and a control motor 9b for driving the damper 9a. Numeral 10 controls the fuel by the proportional valve 5 in accordance with the target combustion amount, and inputs an opening signal of the damper 9a to open the damper 9a so that the air amount detected by the air flow sensor 3 is constant. An arithmetic unit that controls the degree.

Next, the operation will be described. Also in this embodiment, FIG. 2 is used as a characteristic diagram of the amount of air supplied to the burner 1 and the output characteristic of the air flow sensor 3, and the characteristic equation in the initial state is y = ax. FIG. 7 is a characteristic diagram of the amount of air supplied to the burner 1 and the degree of opening of the damper 9a. The characteristic equation in the initial state is r = bx. However, since the exhaust gas from the combustion chamber 1a is discharged outside, when the wind is received at the exhaust port 1b, the opening of the damper 9a must be increased to obtain the same amount of air as when there is no wind. Therefore, in this case, r in FIG.
= B ₂ x. The following air flow sensor 3
The procedure for correcting the error due to the secular change is described in the first embodiment.
Since the rotation speed of the fan motor 2a in the above description is the same as that in which the opening degree of the damper 9a is set, the description is omitted.

The flow rate detector in the first and second embodiments is
Although the air flow sensor 3 has a structure in which a resistance temperature sensor is provided on a semiconductor thin film provided in an air pipe, a flow rate detection for detecting an air flow rate from a differential pressure between an inlet air pressure and an outlet air pressure of the burner 1 is performed. The same effect can be obtained with a vessel.

[0021]

As described above, according to the first aspect of the present invention, each time the burner is ignited, the average value of the rotation speed of the fan motor is obtained, and the average value of the rotation speed of the fan motor is calculated. If there is a difference, the initial value of the output of the flow detector is configured to be corrected, so even if the error of the detection output of the air amount becomes large due to aging of the flow detector, this error is corrected, and the burner is corrected. Has an effect that the ideal air-fuel ratio control can be favorably maintained.

According to the second aspect of the present invention, the average value of the opening degree of the damper is obtained every time the burner is ignited, and if there is a difference between the initial value and the average value of the opening degree of the damper, the flow rate is detected. It is configured to correct the initial value of the output of the burner, so even if the error of the detection output of the air amount becomes large due to aging of the flow rate detector, this error is corrected, and the ideal air-fuel ratio control of the burner is performed. Has an effect that can be maintained favorably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a combustion control device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of an amount of air supplied to a burner and an output of an air flow sensor.

FIG. 3 is a characteristic diagram of an amount of air supplied to a burner and a rotation speed of a fan motor.

FIG. 4 is a timing chart showing a burner ignition operation.

FIG. 5 is a flowchart illustrating a procedure for correcting an error due to aging of the air flow sensor.

FIG. 6 is a configuration diagram showing a combustion control device according to an embodiment of the present invention.

FIG. 7 is a characteristic diagram of an amount of air supplied to a burner and an opening degree of a damper.

FIG. 8 is a configuration diagram showing a conventional combustion control device.

FIG. 9 is a characteristic diagram of an amount of fuel and an amount of air supplied to a burner.

[Explanation of symbols]

 Reference Signs List 1 burner 2, 2a fan motor 3 air flow sensor (flow detector) 8, 10 computing unit 9a damper

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasuji Morita 1-12-2 Kawana, Fujisawa-shi, Kanagawa Yamatake Honeywell Co., Ltd. Fujisawa Plant (56) References JP-A-3-129207 (JP, A) Kaihei 3-286919 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F23N 3/08 F23N 1/02 F23N 5/18 101

Claims (2)

(57) [Claims] An air flow supplied to a burner is detected by a flow detector, and a rotation speed of a fan motor is controlled based on an output of the flow detector to make the air flow supplied to the burner constant. In the combustion control device, every time the burner is ignited, an air amount is supplied so that the output of the flow rate detector becomes a constant initial value, and the number of rotations of the fan motor for each ignition time is stored, and the rotation speed of the fan motor is stored. If there is a difference between the stored initial value of the fan motor speed and the average value, the initial value of the output of the flow rate detector is calculated as the speed of the fan motor at which the difference occurs. A combustion control device, comprising: a calculator that corrects based on an initial value and an average value. 2. A combustion for detecting an amount of air supplied to a burner by a flow detector and controlling an opening degree of a damper based on an output of the flow detector to keep the amount of air supplied to the burner constant. In the control device, every time the burner is ignited, an air amount is supplied so that the output of the flow rate detector becomes a constant initial value, and the opening degree of the damper for each ignition time is stored and the opening degree of the opening degree of the damper is stored. An average value is obtained, and if there is a difference between the stored initial value of the damper opening and the average value, the initial value of the output of the flow rate detector is compared with the initial value of the opening of the damper having the difference. A combustion control device comprising a computing unit that corrects based on a value.