JPH03164614A - Burner combustion controller - Google Patents

Abstract

PURPOSE:To stably implement combustion control by providing a pressure gauge for detecting pressure between internal and external containers and controlling with use of a pressure regulator the amount of fuel supplied to a burner by comparing an output value from the pressure gauge with a set value, and further controlling the amount of air by receiving an output signal from an optical sensor for monitoring the flame of the burner. CONSTITUTION:A burner is provided toward the inside of a double structure inside container 2, and the amounts of fuel and air supplied to the burner are adjusted, and further the temperature of the fluid between double structure internal and external containers 5 is controlled to a predetermined value for controlling the amount of combustion. A pressure gauge 9 is provided to detect pressure between the internal and external containers 5, and a pressure regulator 10 controls the amount of the fuel supplied to the burner 4 by comparing the output value from the pressure gauge 9 with a set value. Further, there are provided an optical sensor for monitoring the flame 6 of the burner and a combustion control device 19 for controlling the amount of air by receiving an output signal from the optical sensor. By the regulation of the amount of the fuel by the pressure regulator 10 and by the control of the amount of air by the combustion control device 19 on the basis of the signal from the optical sensor, the proper fuel amount and the air amount can always be maintained to assure effective combustion state even with a boiler whose load is greatly varied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion control device for a burner used in combustion equipment such as a boiler.

(Prior art) In a burner that burns liquid or gaseous fuel,
It is desirable to maintain the combustion state optimally during combustion.
The combustion state of the flame in the burner generally varies greatly depending on the mixing ratio of air and fuel (air ratio or 02 concentration ratio in exhaust gas). In order to maintain good combustion conditions, conventionally a combustion control device is provided for the combustion device, and this combustion control device performs exhaust gas feedback control to adjust the amount of air supplied to the combustion device and, by extension, the air ratio. Many things are being done. In addition, the light intensity signal generated by the burner flame is converted into an electrical signal using a semiconductor such as a phototransistor, photodiode, or solar cell, and the integrated value of the power spectrum obtained as a result of frequency analysis of the vibration waveform is used. Please refer to Japanese Patent Laid-Open No. 63-306310 for a method and apparatus for controlling combustion.

(Problems to be Solved by the Invention) In the invention described in the above publication, when controlling the amount of combustion air, it is necessary to improve followability to changes in combustion conditions, especially when controlling the amount of air when the fuel flow rate increases. The functions for performing practical combustion control, such as correction for variations in power spectrum ratio or correction for optimum air ratio at partial load, which is unique to the combustor, were somewhat insufficient. That is, the frequency components of the light vibrations emitted from the combustion flame are constantly changing. JP-A No. 63-306310 mentioned above
The combustion control method disclosed in the publication was developed based on the fact that there is a strong correlation between changes in the power spectrum ratio of optical vibrations and changes in the combustion state caused by changes in the air ratio, etc. .

However, in order to actually use the optical power spectral ratio as a combustion control index, variations in the optical power spectral ratio caused by the combustion characteristics of the flame have become a problem. In this interlayer, moving average processing is performed to reduce the width of variation and eliminate short-time changes, and to obtain the optimal moving average (L) according to the characteristics of the combustor, the moving average number table is used to move the layer. This problem can be solved by making the average number of times configurable.

On the other hand, when applying the combustion control method described above to combustion equipment such as a boiler with large load fluctuations, it is necessary to perform air ratio control in accordance with changes in combustion amount. Incidentally, each combustor has its own unique combustion load characteristics. i.e. load 100
%, the air ratio is 11, and at 80% load, the air ratio is 12.
, at 50% load, the air ratio must be adjusted to an appropriate air ratio, such as 13, depending on the change in combustion amount. Therefore, the optical power spectrum ratio is also different for each combustion!
There are appropriate settings depending on the situation. For this reason, a line table of optical power spectrum ratio set values corresponding to each combustion amount is set up, and the set values and the current state are compared through this line table.

Control is carried out in this way, but if the follow-up is poor, especially when increasing the air volume in accordance with the rate at which the fuel increases, the required amount of air may not be obtained, causing problems such as black smoke and misfires. This may cause problems. For this purpose, it is necessary to know the fuel flow rate, so the rate of change of the output signal of the flow meter or the opening signal of the fuel valve is constantly monitored using a rate of change monitor.
For a sudden increase in combustion amount above a certain value, PID (
Propartional Integral and
Opening degree information was further added to the Derivative Control (Derivative Control) output signal and output.

In addition, if the current value of the power spectrum ratio changes beyond the lower limit value according to the set value of the polygon table, the lower limit monitor displays the result of ratio calculation corresponding to the rate of change in the same way as the current change rate. This is added to the PID output signal to further increase the amount of air. Incidentally, among the lower limit monitor outputs of the rate of change of the fuel flow rate and the power spectrum ratio, the one having a larger absolute value is selected and added to the PID output signal.

The present invention was made in view of the current situation, and by adding the control functions described above, it is possible to stably perform combustion control even for combustion equipment such as boilers that have sudden load fluctuations. The purpose is to provide a combustion control V4 device.

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides a burner 4 facing into the double-structured inner container 2, and reduces the amount of fuel and air added to the burner 4. In a smoke tube boiler, the combustion amount is controlled by adjusting the temperature of the liquid stored between the inner and outer containers (chamber 5) of the double structure to a constant value, and the pressure between the inner and outer containers is detected. A pressure regulator 10 is provided to control the amount of fuel supplied to the burner 4 by comparing the output value of the pressure gauge 9 with a set value. The structure includes an optical sensor that monitors the flame 6, and a combustor (pushing device t+9) that controls the amount of air in response to an output signal from the sensor.

(Function) With such a configuration, the pressure regulator 10 adjusts the fuel amount and the combustion control device 19 controls the air amount based on the signal from the optical sensor, so that the appropriate amount of fuel and air are always maintained. Since the amount can be maintained, efficient combustion conditions can be obtained even in boilers with large load fluctuations.

(Example) An example of the present invention will be described below with reference to FIG. l
is a smoke tube boiler having a double structure, 2 is its inner vessel, and 3 is its outer vessel. A burner 4 is installed toward the inside of the inner container 2, and by controlling the flow of fuel and air to the burner 4, the double-structured inner container 2 is heated.
The temperature of the liquid (generally water) contained in the chamber 5 between the outer container 3 and the outer container 3 is controlled to a constant value. 6 is the flame emitted by the burner 4, 7 is the leg of the smoke tube boiler l, and 8 is the floor. A pressure gauge 9 is provided in the upper center of the outer container 3 to detect the pressure in the chamber 5 within the inner container 2 and the outer container 3. This pressure gauge 9 is connected by a cable 11 so as to send an output signal to a pressure regulator lO.

A fuel supply pipe 2 and an air supply pipe 13 are connected to the burner 4, and the base end of the fuel supply pipe 12 is connected to a fuel tank and a fuel pump (not shown). Further, a fuel control valve 14 is provided in the middle of the fuel supply pipe 12, and its opening degree is adjusted by a modutrol motor 16 connected via a link mechanism 15. Since the Modutrol motor 16 is energized and controlled by the pressure regulator 10, it is connected to the pressure regulator IO by a cable 17, and is also connected to a combustion control device 19 (described later) by a cable 18, so that its state can be controlled during combustion. The control device 19 is operated manually.

A blower fan 20 is connected to the air supply pipe 13, and
An air control valve 22 whose opening and closing are controlled by a Modutrol motor 21 is provided between the blower fan 20 and the burner 4 . Since the modutrol motor 21 receives commands from the combustion control device 19, it is connected to the combustion control device 19 by a cable 23. A viewing window 24 is provided at a portion of the smoke tube boiler l facing the burner 4.
An optical sensor (not shown) is attached to this viewing window 24. As the optical sensor, a well-known phototransistor, photodiode, or the like can be used.

The optical sensor is connected by a light guide 25 to a sensor amplifier 26 , and the sensor amplifier 26 is connected to a combustion control device 19 by a cable 27 .

This device having such a configuration operates as follows. First, the chamber 5 is filled with a heating fluid such as water, and then the burner 4 is ignited by igniting a pilot burner (not shown). As the fuel, gas or heavy oil can be considered. In addition to fuel, the burner 4 is also supplied with an air flow generated by a blower fan 20 . Burner 4
The state of the flame 6 is constantly monitored by an optical sensor, and the information is amplified to an appropriate level by a sensor amplifier 26 and then input to the combustion control device 19. On the other hand, a pressure gauge 9 provided at the center of the upper part of the outer container 3 detects the pressure in the chamber 5 formed in the inner container 2 and the outer container 3, and sends its output signal to the pressure regulator lO. .

The pressure regulator 10 compares the signal from the pressure gauge 9 with a preset pressure value, and then adjusts the signal to maintain a constant pressure. This adjustment is performed by controlling the rotational direction of the modutrol motor 16 and opening and closing the fuel control valve 14. On the other hand, the opening signal of the fuel control valve 14 is detected by a signal applied to the modutrol motor 16 using a not-shown potentiometer or the like, and is input to the combustion control device 19 via a cable 18. The combustion control device 19 takes in both the opening signal and the signal from the optical sensor mentioned above, and controls the air control valve 22 based on the result of performing control calculations to be described later.
The Modutrol motor 2■ will be operated to drive the motor. An output signal for this purpose is transmitted from the combustion control device 19 to the Modutrol motor 2 via a cable 23.
1 can be conveyed.

Next, referring to FIG. 2, the details of the control performed inside the combustion control device 19 shown in FIG. 1 will be explained. Sensor amplifier 2
The electrical signal input from 6 is processed by FFT (Fast Fo
The vibration frequency is analyzed by the processing unit 28 and output as a power spectrum ratio, and then averaged by the moving average processing unit 29 by the number of times set in the moving average number table 30. 32 and the Pv lower limit monitor 33. The current fuel flow rate or fuel adjustment is stored in the polygon table 34 through a moving average processing unit 37 that performs a moving average of the fuel flow meter 35 or the opening signal of the fuel control valve at the number of times set in the moving average number table 35. The valve opening signal is manually input.

This polygon table 34 selects a power spectrum ratio set value corresponding to the fuel flow rate or fuel control valve opening signal from the table and outputs it to the adder 32, and at the same time outputs the power spectrum ratio lower limit set value at this time to the Pv lower limit monitor. It is output to 33.

The adder 32 compares the set value output from the line table 34 with the current value manually input from the moving average processing section 29, and the result is led from the dead zone processing section 38 to the PID calculation section 39 to deal with deviations. The resulting output value is output to the adder 40.

In the adder 40, the power spectrum ratio lower limit 1+a set in the polygon table 34 is determined by the Pv lower limit monitor 33.
The power spectrum ratio is compared with the current value of the power spectrum ratio inputted from the branching unit 31, and if the current value is below the power spectrum lower limit set value, the spectrum ratio ratio is adjusted so as to output a corrected output according to the amount of change. The arithmetic unit 41 calculates the result and outputs it to the comparison and selection section 42. The current fuel flow rate or fuel valve opening signal is calculated as a rate of change by a rate of change monitor 44 from a branching unit 43 and is further inputted to the comparison and selection unit 42 via a rate of change monitor ratio calculation unit 45 .

The comparison and selection section 42 selects the one with the largest absolute value among the spectrum ratio lower limit rate of change and the fuel flow rate or fuel valve opening signal and outputs it to the adder 40 . The adder 40 adds the signal output from the PID calculation section 39 and outputs the result to the output limiter 46 . The operation output for which the upper limit output has been set by the output limiter 46 is output to the air ff1JI control valve 47.

(Effects of the Invention) As described above, the present invention provides a pressure gauge for detecting the pressure between the inner and outer containers, and compares the output value of this pressure gauge with a set value to determine the amount of fuel to be supplied to the burner. This is because the structure includes a pressure regulator for controlling the burner, an optical sensor for monitoring the flame of the burner, and a combustion control device for controlling the amount of air in response to the output signal of the optical sensor. Since a combustion control device can be obtained that can maintain the air ratio of thermal equipment such as a boiler with large load fluctuations at an optimal value over all load ranges, the efficiency of the combustor can be improved. As a result, the amount of fuel used can be reduced, contributing to a reduction in energy costs as well as a reduction in the amount of CO2 generated. In addition, because of low O8 combustion, NOxp output can be reduced, which will also help preserve the global environment.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the control contents performed inside the combustion control device in FIG. 1. l-Fire tube boiler 2-Inner container 3...Outer container 4--Burner 5-Chamber 6--Flame 9-Pressure gauge 1-Pressure regulator 14--Fuel control valve 16.21...Modutrol motor 19-Combustion control device 20-・Blower fan 22-・Air control valve 1 11 Buried tube boiler 2 Circle side 8 vessel 39 + side container 4 Barb 5-ri 6 Flame 9 Pressure 773t 10 Pressure adjustment IP meter V* f !PrII*ff valve Ventilation fan 22 Air conditioning well 2nd figure

Claims (1)

[Claims] (1) Install the burner toward the inside of the double-structured inner container,
In a smoke tube boiler, the amount of combustion is controlled by adjusting the amount of fuel and air added to the burner and controlling the temperature of the liquid stored between the inner and outer containers of the double structure to a constant value. A pressure gauge is provided to detect the pressure between the containers, and the amount of fuel supplied to the burner is controlled by a pressure regulator by comparing the output value of the pressure gauge with a set value. 1. A combustion control device for a burner, comprising: an optical sensor for monitoring a flame; and a combustion control device for controlling the amount of air in response to an output signal from the optical sensor.