JP3561309B2 - Boiler combustion control method - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a boiler combustion control method that performs three-position control of high combustion, low combustion, and stop, and more particularly to a boiler combustion control method that uses a rotation speed control device to control a blower that sends combustion air. .
[0002]
[Prior art]
In general, a boiler sends fuel and air to a burner and burns it in a combustion chamber. However, if the amount of air is too large, the excess air deprives the combustion chamber of heat and sends extra air. Will be wasted. If the amount of air is insufficient, complete combustion cannot be performed and a smoke state is caused, resulting in waste of fuel.
[0003]
Conventionally, in a three-position control boiler that controls high combustion, low combustion, and stop, the fuel supply is controlled by opening and closing an electromagnetic valve, and the air supply is provided with a damper in an air passage provided with a blower having a constant rotation speed. It is controlled by opening and closing. The control signals for controlling the fuel supply and the air supply are output simultaneously, and the solenoid valve for controlling the fuel supply operates instantaneously. The damper for controlling the air supply operates within one second, so there is no control problem. However, since the blower is always operated at a constant rotational speed corresponding to high combustion, there is a problem that the power efficiency particularly during low combustion is deteriorated.
[0004]
Therefore, a control method for supplying a required amount of air has been attempted by providing a rotation speed control device for controlling the rotation speed of the blower in a three-position control boiler and controlling the rotation speed of the blower. However, while the solenoid valve for controlling the fuel supply operates instantaneously, the control of the air volume by the rotational speed control device has a delay in the response of the acceleration / deceleration characteristics of the blower as shown in FIG. That is, acceleration deceleration of the actual acceleration time t _{31 =} response delay time t ₃₃ becomes acceleration time of the rotational speed control device t _{32 +} blower, also deceleration actual deceleration time t _{34 =} speed control system of the blower Time t ₃₅ + response delay time t ₃₆ of the blower is obtained, and the time required until the predetermined amount of air is reached is about 10 seconds.
[0005]
As a result, when the amount of fuel that shifts from low combustion to high combustion increases, the amount of fuel becomes excessive and black smoke is generated. On the contrary, when the amount of fuel decreases, the amount of air becomes excessive and blowout may occur. In FIG. 3, the solid line indicates the output frequency of the rotation speed control device, and the broken line indicates the rotation speed of the blower.
[0006]
FIG. 4 is a diagram showing characteristics when a rotation speed control device is used in a conventional control method. This is the operation of the boiler of the three-position control. When the blower is started and the low-combustion air amount is reached, the fuel is ignited and the low-combustion operation is started. When moving to high fire than the low combustion, the fuel reaches the fuel supply amount required for a high combustion (time required to increase the fuel) time t ₄₂ after the elapse, the air amount reaches the amount required time t ₄₁ After (t ₄₂ <t ₄₁ ) has elapsed (the time required for increasing the amount of air). Accordingly, during this time, the combustion air is insufficient, black smoke is generated, and the combustion becomes unstable.
[0007]
Also, when going to the low combustion than high combustion, the fuel is reduced to a fuel supply amount necessary for low combustion after the elapsed time t ₄₄ (time required for reduction of the fuel), but the air is reduced to a low amount of combustion air Is after a time t ₄₃ (t ₄₄ <t ₄₃ ) (time required for reducing the amount of air). Therefore, during this time, the air becomes excessive and blowout may occur.
[0008]
As a countermeasure, there is a method in which the control of the rotation speed of the blower and the control of the air volume by a damper are used in combination as disclosed in Japanese Patent Application Laid-Open No. 61-276623. FIG. 5 is a diagram showing a configuration example of a control device for the boiler-burning furnace. As shown in the figure, air 55 required for combustion is supplied to a burner 53 through a blower 54 and a damper 63. On the other hand, the fuel 52 is adjusted by the flow controller 51, supplied to the burner 53, mixed with the air 55, and burned. In the combustion furnace 58, the boiler 59 is heated to generate steam 65, and the steam 65 is sent out through the distillation tube 64.
[0009]
The pressure detector 60 detects the vapor pressure, controls the motor 61 based on the output signal, controls the flow controller 51 through the link 62, controls the fuel inflow, and opens the damper 63. To adjust the air volume. Furthermore, since the amount of air for complete combustion cannot be obtained only by adjusting the damper 63, the number of rotations of the blower 54 is controlled to adjust the amount of air. The rotation speed of the blower 54 is controlled by the output frequency of the rotation speed control device 57 to adjust the air volume. Rpm as the combustion state in accordance with the opening degree of the Na 53 (oxygen concentration by O ₂ meter 66, smoke condition by the output and visual flue gas meter 67) becomes the best - the frequency setting unit 56 Bas The blower 54 is controlled via the control device 57. In the figure, reference numeral 68 represents a chimney, and reference numeral 69 represents smoke.
[0010]
[Problems to be solved by the invention]
However, most of the above prior arts are applied to a boiler of a proportional control method, and a combustion control method applied to a boiler such as a three-position control method has not been established. In addition, the above-described control method using both the rotation speed control of the blower by the rotation speed control device 57 and the air volume control by the damper 63 increases costs and eliminates the merit of using the rotation speed control device 57. There is also a method of increasing the capacity of the rotation speed control device 57 to increase the acceleration / deceleration time as compared with the capacity of the drive motor of the blower. However, if the capacity of the drive motor is increased, it becomes difficult and the cost increases. there were.
[0011]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above problems, and has been made in consideration of the above problems, and has been made in consideration of the above problems. It is an object to provide a combustion control method.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a blower for feeding combustion air, an air amount adjusting means for adjusting an amount of combustion air sent from the blower, and a fuel supplied by changing a fuel supply amount in high combustion and low combustion. In a boiler combustion control method comprising a supply means and a control means for controlling these, and controlling a combustion of a boiler, a rotation speed control device for controlling a rotation speed of a blower is provided as an air amount adjusting means, and a low combustion to a high combustion When moving to, the control means increases the rotation speed of the blower via the rotation speed control device, detects the amount of air from the blower, and adjusts the air amount to an appropriate air amount before reaching the air amount necessary for high combustion. Then, the fuel supply means supplies a high combustion fuel amount, and when shifting from high combustion to low combustion, the control means lowers the rotation speed of the blower via a rotation speed control device and detects the air amount from the blower. Sir Once in the proper amount of air before the air amount reaches the amount of air required to low combustion, and supplying the fuel amount of the low combustion by the fuel supply means.
[0013]
[Action]
In the boiler combustion control method of the present invention, when shifting from low combustion to high combustion, the rotation speed of the blower is increased by the control means via the rotation speed control device, the amount of air from the blower is detected, and the air amount is increased. When the amount of air reaches an appropriate amount before reaching the required amount of air, the fuel supply means supplies a high-combustion amount of fuel, so that there is no black smoke due to lack of combustion air as in the past. . Further, when shifting from high combustion to low combustion, the rotation speed of the blower is reduced by the control means via the rotation speed control device, the amount of air from the blower is detected, and the air amount reaches the air amount necessary for low combustion. When the previous appropriate air amount is reached, the fuel supply means supplies the low-combustion fuel amount, so that the blow-out due to the excess air amount unlike the conventional case is eliminated. Further, since the air required for combustion is always sent by the blower, the power consumption efficiency is improved.
[0014]
【Example】
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a boiler facility for implementing a boiler combustion control method of the present invention. In FIG. 1, reference numeral 11 denotes a boiler, and a burner 21 is disposed in a combustion chamber 22 of the boiler 11. The combustion air is supplied to the burner 21 by the blower 13 through the casing 12, the fuel is pumped by the pump 18, and the injection nozzle (shown in FIG. 1) of the burner 21 is passed through the low combustion oil solenoid valve 19 and the high combustion oil solenoid valve 20. )). Here, it is mixed with the combustion air and burns to form a flame in the combustion chamber 22.
[0015]
A wind pressure detector 14 is provided at a predetermined position of the casing 12, and an output signal thereof is input to a control unit 16. The rotation speed control device 15 receives a command from the control unit 16, controls the rotation speed of the blower 13, and adjusts the air volume to an appropriate amount. A steam pressure switch 17 for detecting a steam pressure is provided in the boiler 11, and an output signal thereof is input to the control unit 16. The control unit 16 controls opening and closing of the low combustion oil solenoid valve 19 and the high combustion oil solenoid valve 20, and controls the supply of fuel from the pump 18 through the low combustion oil solenoid valve 19 and the high combustion oil solenoid valve 20.
[0016]
FIG. 2 is a diagram showing a change in air amount and fuel supply timing in the boiler combustion control method of the present invention. This combustion control method is a three-position control method for controlling high combustion, low combustion, and stop. In low combustion, fuel is supplied from the low combustion oil solenoid valve 19, and during high combustion, the fuel is further supplied from the high combustion oil solenoid valve 20 in parallel. (See FIG. 1).
[0017]
The fuel supply timing will be described with reference to FIG. When a start signal a to the speed control device 15 from the control unit 16 is output, the speed control unit 15 activates the blower 13, the amount of air fed from the blower 13 through the casing 12 is time t _{21 (acceleration} After time), the air volume required for low combustion is reached. Subsequently, the ignition and low combustion valve open signal b is output and sent to the burner 21 and the low combustion oil solenoid valve 19 to open the low combustion oil solenoid valve 19 to ignite and start the low combustion operation.
[0018]
When the high combustion signal c is output from the control unit 16, the rotation speed control device 15 accelerates the blower 13 as shown in the drawing. After this the time t _{22 (acceleration} time), the amount of air fed through the casing 12 reaches the amount of air required for high combustion. Further, the control unit 16 outputs a high combustion signal c, when detecting that the increased time t ₂₃ after the output signal of the air pressure detector 14, or the amount the amount of air is appropriate from the rotational speed of the blower 13, the high The combustion valve opening signal d is output, the high combustion oil solenoid valve 20 is opened, and fuel necessary for high combustion is supplied to start high combustion operation.
[0019]
Further, when shifting from high combustion to low combustion, when the low combustion signal e is output from the control unit 16, the rotation speed control device 15 decelerates the blower 13 as shown in the figure, and after a time t ₂₄ (deceleration time). The amount of air sent through the casing 12 is the amount required for low combustion. After the control unit 16 the time t ₂₅ elapses outputs a low combustion signal e, the output signal of the air pressure detector 14, or, when detecting that the air quantity from the rotational speed of the blower 13 is reduced to an appropriate amount, high combustion valve A close signal f is output, and the high combustion oil solenoid valve 20 is closed. At the time of fire extinguishing, a fire extinguishing signal g is output, the low combustion oil solenoid valve 19 is closed, and then a stop signal h is output to stop the blower 13.
[0020]
As described above, in the boiler combustion control method of the present invention, when shifting from low combustion to high combustion, the control unit 16 first outputs the high combustion signal c to the rotation speed control device 15 to increase the rotation speed of the blower 13 and increase the air amount. When the fuel reaches an appropriate amount for high combustion, a high combustion valve open signal d is output, the high combustion oil solenoid valve 20 is opened, and the fuel is increased to the amount required for high combustion. Will not occur. Further, when shifting from the high combustion to the low combustion, the control unit 16 outputs a low combustion signal e to the rotation speed control device 15, and when the rotation speed of the blower 13 is reduced to an appropriate air amount for the low combustion, the high combustion Since the oil solenoid valve 20 is closed, blowout does not occur as in the related art. Also, power efficiency is improved.
[0021]
In the above embodiment, three-position control of high combustion, low combustion, and stop was described as an example. However, the boiler combustion control method of the present invention is not limited to this, and may be applied to, for example, combustion control of four-position control. What you can do is obvious.
[0022]
【The invention's effect】
As described above, according to the present invention, the following excellent effects are expected.
(1) When shifting from low combustion to high combustion, the rotation speed of the blower is increased by the control means via the rotation speed control device, the amount of air from the blower is detected, and the amount of air is reduced to the amount of air necessary for high combustion. When the amount of air reaches an appropriate amount before reaching, the amount of fuel of high combustion is supplied by the fuel supply means, so that no black smoke is generated or combustion due to the generation of black smoke is not unstable. Further, when shifting from high combustion to low combustion, the rotation speed of the blower is reduced by the control means via the rotation speed control device, the amount of air from the blower is detected, and the amount of air reaches the amount of air required for low combustion. When the previous appropriate air amount is reached, the fuel supply means supplies the low-combustion fuel amount, so that the blow-out due to the excess air amount unlike the conventional case is eliminated.
[0023]
(2) Since air necessary for combustion is always sent by the blower, the power consumption efficiency is improved, and the running cost is reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a boiler facility for implementing a boiler combustion control method of the present invention.
FIG. 2 is a diagram showing a change in air amount and fuel supply timing in the boiler combustion control method of the present invention.
FIG. 3 is a diagram showing acceleration / deceleration characteristics of a blower controlled by a rotation speed control device.
FIG. 4 is a diagram showing characteristics when a rotation speed control device is used in a conventional control method.
FIG. 5 is a diagram showing a configuration example of a conventional boiler-burning furnace control device.
[Explanation of symbols]
11 Boiler
DESCRIPTION OF SYMBOLS 12 Case 13 Blower 14 Wind pressure detector 15 Revolution control device 16 Control part 17 Steam pressure switch 18 Pump 19 Low combustion oil solenoid valve 20 High combustion oil solenoid valve 21 Burner 22 Combustion chamber

Claims (3)

A blower that sends combustion air, an air amount adjusting unit that adjusts the amount of combustion air sent from the blower, a fuel supply unit that changes the amount of fuel supply in high combustion and low combustion, and a control unit that controls these. A boiler combustion control method comprising: controlling boiler combustion;
Providing a rotation speed control device for controlling the rotation speed of the blower as the air amount adjustment means,
When shifting from the low combustion to the high combustion, the control means increases the rotation speed of the blower through the rotation speed control device , detects the amount of air from the blower, and detects the amount of air required for the high combustion. When the amount of air reaches an appropriate amount before reaching the amount, the fuel supply means supplies a high combustion fuel amount, and when shifting from the high combustion to low combustion, the control means controls the rotation speed control device via the rotation speed control device. The number of rotations of the blower is reduced, and the amount of air from the blower is detected. When the amount of air reaches an appropriate amount before reaching the amount of air required for the low combustion, the amount of low combustion fuel is increased by the fuel supply means. Boiler combustion control method, characterized in that: The boiler combustion control method according to claim 1, wherein the air amount is detected from a discharge pressure of the blower, and the fuel amount is increased or decreased by the discharge pressure. The boiler combustion control method according to claim 1, wherein the amount of air is detected from the number of rotations of the blower, and the amount of fuel is increased or decreased according to the number of rotations.

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