JPH02178517A - Device to control burner combustion - Google Patents

Abstract

PURPOSE:To make it possible to control exactly the air volume supplied to a burner by providing an ion detector which detects the ionic current in the flame and connecting an ionic current vibration adjustment meter to an air flow rate correction device and connecting said air flow rate correction device to an air flow rate regulating valve. CONSTITUTION:An ion detector 17 to detect ionic current which develops between two electrodes 13a and 13b which are provided to enter the end section of a flame 3 emanating from a burner 2 or between one electrode 13 provided in said end section and a terminal 15 provided at the flame emanating section 14 of the flame 3 of the burner 2 is connected to a frequency analyzer 19, and this frequency analyzer 19 is connected to ionic current vibration adjustment meter 20 which receives the spectrum signal obtained by the frequency analyzer 19. And, said adjustment meter 20 is connected to an air flow rate correction device 11 which compares the signals from the adjustment meters with a most suitable state of combustion which is beforehand stored in a memory and issues the signal to cancel the deviation in the comparison, and said air flow rate correction device 11 is connected to a flow rate regulating valve 8 which carries out air flow rate regulation. With this arrangement the state of the flame 3 can be detected exactly so that the volume of air added to the burner 2 can be controlled exactly.

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.
Conventional technology for this purpose involves converting the light intensity signal generated by the burner flame into an electrical signal using a semiconductor such as a phototransistor, photodiode, or solar cell, and then converting the light intensity signal generated by the burner flame into an electrical signal by analyzing the frequency of the vibration waveform. A method and apparatus for controlling combustion using the integral value of the spectrum has been proposed (Japanese Patent Application No. 139456/1982).

(Issues to be Solved by the Invention) In the method of utilizing light generated from a flame, which has been described above as the prior art, a plurality of burners 2 are connected to the furnace 1, and the first
If they are installed facing each other as shown in Figure b, it may be impossible to distinguish and detect the flame 3 of a particular burner, or if the burner flame is directly applied to the object to be heated, the optical sensor may This sometimes resulted in the inability to detect light. Furthermore, since elements such as photodiodes are required to convert light from the flame into electrical signals, special consideration must be given to these easily damaged elements.

The present invention was made in view of the current situation where problems remain with methods that utilize light generated from flames. The object of the present invention is to provide a device that performs combustion control.

(Means for Solving the Problems) The present invention provides, as a means for solving the above problems, between two electric hook rods 13a and 13b provided so as to enter the tip of the flame 3 emitted by the burner 2, Alternatively, a detector 17 is provided to detect the ionic current generated between one electrode rod 13 provided in the same part and a terminal 15 provided in the radiation part 14 of the flame 3 of the burner 2, and the detector 17 is connected to the amplifier 18. The frequency analyzer 19 is connected to an ion current oscillation controller 20 that receives the power spectrum signal obtained by the frequency analyzer 19, and the ion current oscillation controller 20 is connected to a frequency analyzer 19 via a The ion current vibration controller 20
The air flow rate compensator 11 is connected to an air flow m corrector 11 which compares the signal from a pre-stored optimum combustion state with a pre-stored optimum combustion state and generates a signal to eliminate the deviation, and the air flow rate corrector 11 is connected to a meteor adjustment device which adjusts the air flow rate. It has a configuration in which it is connected to a valve 8.

(Function) With the configuration described in -1-, the state of the flame 3 can be detected without using the light in the flame 3, without being affected by the arrangement of the burner 2 or the direct contact of the flame 3 with the object to be heated. , will be done accurately. Therefore, the amount of air added to the burner 2 can also be controlled accurately.

(absolutely devastated) Next, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the reference numeral 1 indicates a furnace for heat-treating a metal product shade. A burner 2 is attached to this furnace 1 to generate a flame 3. A fuel supply pipe 4 and a combustion air supply pipe 5 are connected to the burner 2 . The fuel supply pipe 4 is provided with a flow control valve 6 and a flow meter 7, and the combustion air supply pipe 5 is provided with a flow control valve 8. The opening degree of the fuel meteor control valve 6 is controlled by a temperature controller 9. That is, a thermometer 10 is installed in the furnace l, and the temperature controller 9 receives a signal from this thermometer lO and the flow meter 7.
The combustion amount (fuel flow rate) necessary to obtain the set temperature is calculated from the difference between the furnace temperature and the set temperature, and is output. This output is given to the fuel warming control valve 6 and the combustion air 7AIn R control valve 8.

Therefore, when the temperature inside the furnace deviates from the set temperature, the amount of fuel and combustion air is adjusted so that the temperature returns to the set temperature.

The flow rate of combustion air relative to the flow of fuel is controlled by a temperature controller 8.
Although it is calculated based on the fuel meteor, it is not preferable that this value is directly applied to the combustion air meteor control valve 8. For example, if the door (not shown) of the furnace I is opened and air enters the class I, if the meteor control valve 8 is directly controlled with the output calculated based on the fuel meteor, the exhaust gas loss will increase. Furthermore, if the state of atomization of the fuel deteriorates due to an abnormality in the burner 2, if left untreated, a large amount of soot will be generated due to poor combustion. In order to eliminate such inconvenience,
The output from the temperature controller 9 is corrected by a combustion air flow rate corrector 11 and then output to the meteor control valve 8.

The combustion air flow rate corrector 11 and the temperature regulator 9 constitute a combustion air flow rate adjustment section 12 . A correction output for the combustion air flow rate corrector 11 is produced by the following combustion control device. Let me explain this. An electrode rod 13 is attached to a position facing the flame 3 generated by the burner 2 of the furnace 1, and a terminal 15 is provided on the flame radiation fis 14 of the burner 2.

The electrode rod 13 is connected to the input side of the ion current interrupting device 16, and the output side of the ion current interrupting device 16 is connected to the input end of the detector 17. A terminal 15 is also connected to the detector 17, so that the detector 17 detects the ionic current in the flame 3.

The aforementioned ion current interrupting device I6 functions to periodically interrupt the ion current signal.

The output side of the detector I7 is connected via an amplifier 18 that amplifies the detected ion current signal to a frequency analyzer 19 consisting of an FFT analyzer or the like, so that frequency analysis of the ion current signal is performed. . Frequency analyzer 1
Ion 1 is on the output side of 9! A flow vibration controller 20 is connected. This ion current vibration controller 20 detects the combustion state from the power spectrum signal outputted by the frequency analyzer 19 and the output signal of the ion current cutoff device 16.
This is compared with the optimal combustion state stored in advance, and an air flow rate correction coefficient is determined based on the deviation. Based on the signal, the flow rate controller 12 is used to obtain the flow rate of combustion air necessary to eliminate the deviation. The output will be sent to the flow MR control valve 8.

Here, the signal from the ion current interrupting device 16 that is manually input to the ion current vibration controller 20 will be explained. As mentioned above, the ion current cutoff device 16 periodically cuts off the signal from the electric current 1415. By doing this, the ion current cutoff device 16 can be used to detect the influence of noise on the system.
be done. In other words, when cut off, the ion current swing fj)
'I notify the controller 20 that the interruption is in progress, determine that the power spectrum signal obtained at that time is noise, and remove that amount from the power spectrum signal when it is not interrupted, thereby eliminating the influence of noise. will be removed. Therefore, from the ion current interrupter 16,
The ion current vibration controller 20 is informed whether or not it is currently being cut off.

Next, the operation will be explained.6 As mentioned above, the present invention utilizes the characteristic that the oscillation frequency of the ion current in the combustion flame changes depending on the combustion state when liquid and gaseous fuels are combusted in a combustion device. It is. As a method for detecting changes in the ion current in a combustion flame, there is a method of detecting the current level, but in the present invention, the method is as follows. That is, in order to detect the ion current in the flame 3 generated by combustion, two 'rLt! ! Either the rods 13a and 13b are installed in parallel and the ionic current flowing between them is measured, or one electrode rod 3 is installed in the flame 3 as shown in FIG. 4, and the flame radiation of this electrode rod 3 and the burner 2 is The ionic current signal generated by the terminal I5 provided in the section 14 is detected (see Fig. 1 for the latter).The ionic current signal obtained by any of these methods is
It vibrates as shown in Figure 5. This signal is 1
The signal is input to the frequency analyzer 19, and a power spectrum as shown in FIG. 6 is obtained. In the power spectrum obtained in this way, the level of the higher frequency component changes by changing the air-fuel ratio, which is one indicator of the combustion state, as shown in FIG. There are several methods of converting this change into a control signal, as shown in FIGS. 7 to 13.

First of all, the one in Figure 7 shows the product numerator a B in a specific frequency band where the power spectrum changes greatly due to changes in the combustion state.
This method uses the ratio B/A of the integral value A of all frequency bands. The method shown in FIG. 8 uses the integral value B of a specific frequency band as it is. The method shown in FIG. 9 uses the ratio D/C between the maximum value C in all frequency bands and the maximum value in a specific frequency band. The method shown in FIG. 10 uses the maximum value in a specific frequency band as is. What is shown in Figure 11 is the average value E of the main frequency band and the average value E of the specific frequency band (
This method uses the ratio F/E of i1'lF. 12th
The method shown in the figure uses the average value F of a specific frequency band as is. The last one shown in Figure 13 is the integral (]a
This method uses the ratio B/(A-F3) with respect to the value excluding B.

Any of these methods may be used, but the fourteenth method
The figure shows changes in values determined by the last method, that is, the method shown in FIG. As is clear from this figure, the value determined by this method changes in accordance with the change in the exhaust type (%) of the exhaust gas ot, which is an index of the combustion state. Therefore, by using this ffi, it is possible to control the combustion state. Furthermore, since the measurement is based on the vibration frequency of the -Is flow of ions caused by combustion, the output will be zero if there is no flame.

Due to this reduction, it can also be used as a means for detecting the presence or absence of flame.

Next, the contents of processing within the ion current vibration controller 20 will be explained using FIG. 2. First, in step 2-1, a power spectrum signal is input, and in the next step 2-2, it is determined based on the signal from the ion current interrupting device 16 whether or not the ion current signal line is currently interrupted. In some cases, the process proceeds to step 2-3, and a signal obtained from noise coming from outside the device and noise generated inside the device as shown in FIG. 15 is stored in the memory. If it is determined in step 2-2 that the interruption is not interrupted, the process proceeds to step 2-4, and from the power spectrum signal obtained from the IQ signal from the current flame, step 2
-3, remove the power spectrum component stored in the memory and generate the power spectrum signal from the real flame i).

Next, the Ste/Knob 2-5 calculates the integral value A of all frequency bands of the power spectrum signal as shown in FIG.
In step 2-6, the integral (li B) of the specific frequency band is calculated.Here, the specific frequency band is the one in which the power spectrum is the widest due to changes in the combustion state (the frequency band that changes) Integrate ([C ratio J-B/ (A
−El). On the other hand, the integral value ratio (power spectrum ratio) K of the 8 combustion states for the 5 various fuel flows is determined in advance, and the data is set in the ion current vibration controller 20 and is stored in step 2-8. Find the difference L-J-K from the current integral value ratio J, and step 2-9
The combustion air flow m correction coefficient M is calculated from the deviation.

The combustion air dffli positive coefficient M determined in this manner is output from the ion current vibration controller 20 to the combustion air flow rate corrector 11. The combustion air flow rate corrector 11 is
In addition to the combustion air flow m correction coefficient M, a basic air flow target signal N is received from the temperature controller 9. This reference air flow signal N is calculated by the temperature controller 9 based on the fuel flow likelihood signal. Then, the combustion air TA angle corrector 11 receives signals M and N, performs a correction calculation based on these signals, and outputs the result to the flow control valve 8 to adjust its opening degree.

The example explained above was a case where the present invention was implemented in an industrial furnace, but the present invention can be applied to other than industrial furnaces, such as boilers, etc.
It can be applied to all kinds of combustion equipment, such as gas water heaters, oil/gas hot air heaters, and gas turbine combustors. The one shown in FIG. 17 is an example of a hot air heater.

This hot air heater 21 is an electric rod inserted into the flame 3 generated in the class I! The ionic current generated between 3 and the furnace 1 itself is utilized. 22 is a combustion plate, 23 is an air nozzle, 24 is a gas nozzle, 25 is air, and 26 is gas.

(Effects of the Invention) Since the present invention is a burner combustion control device configured as described above, it overcomes the disadvantages of the conventional method of using light generated from a flame, that is, a plurality of burners in one furnace. Even when two burners are installed facing each other, it is possible to distinguish and detect the flame of a particular burner, and it is also possible to detect when the flame of a burner is directly applied to an object to be heated. effect can be obtained. Furthermore, since it does not depend on light, there is no need to use easily damaged elements such as photodiodes.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Figs. 2 and 2 are flowcharts explaining the processing contents in the ion current vibration controller shown in Fig. 1, and Figs. 3 and 4 are diagrams of the burner. Fig. 5 is a graph showing the change in ion current over time, Fig. 6 is a graph showing the relationship between power spectrum frequency, and Figs. 7 to 13. Figure 14 is a graph for explaining how to convert changes in the level of the higher frequency component into a control signal by changing the air-fuel ratio.
Graph showing the relationship between frequency and power spectrum, Figure 15 is a graph showing the relationship between frequency and power spectrum,
FIG. 16 is a plan view showing an example in which a plurality of burners are provided facing each other in one furnace, and FIG. 17 is a sectional view showing another example of application of the present invention. 1...Furnace 2...Burner 3...Flame 6.8...Flow 1 Control well 1...Air flow rate corrector 13 13a, 13b - Electrode rod 14...Radiating section 5... Terminal 6...Cutoff device 7...Detector 18... 1st band I9...Frequency analyzer 20...Ion current vibration controller patent Applicant: Toyota Motor Corporation, Figure 2, Figure 4 Furnace, 1st cause 1...Furnace 2-Burner 3 Flame 6.8 ・Flow V control 11, air flow 萱精'工器13.13a, 13b--...Electrode rod 14 Famous sentence #f郁15-Naruko 16 ・4-branch device 17 ・Detector 18-11 width device 19 Mantissa analyzer 20 Isai〉Electronic vibration adjustment 5th figure 6th figure 6th figure (Hz) 7th figure Figure 8 t] Wave number 11 Figure 12 Figure 14 Section

Claims (1)

[Claims] (1) Occurs between two electrode rods installed in the tip of the flame emitted by the burner, or between one electrode rod installed in the same area and a terminal installed in the flame emitting part of the burner. A detector for detecting an ion current is provided, the detector is connected to a frequency analyzer via an amplifier, and the frequency analyzer is connected to an ion current oscillation controller that receives a power spectrum signal obtained by the frequency analyzer. The ion current oscillation controller is connected to an air flow rate compensator that compares the signal from the ion current oscillation controller with a pre-stored optimum combustion condition and generates a signal to eliminate the deviation. A combustion control device for a burner, characterized in that an air flow rate corrector is connected to a flow rate control valve that adjusts the flow rate of air.