A kind of single burner flame detecting method and device
Technical field
The present invention relates to a kind of method and apparatus of boiler furnace safety detection, more particularly, relate to a kind of detection method and device of flame of single burner.
Background technology
Large-sized boiler all must have perfect supervision that prevents furnace explosion and control device, finish this function be " boiler furnace safety monitoring system " (FSSS), and the detection of boiler-burner flame is the important component part of this system, and whether its correct detection will directly influence the reliability of whole boiler Furnace Safeguard Supervisory System action.Up to now, domestic production mostly be simple photovoltaic type flame detector, though also be installed in by the burner, the flame of target combustion device can not be separated from background (full burner hearth) flame, from essence is that full furnace flame detects, and they can not really satisfy the FSSS system requirements.The boiler of evaporation capacity more than 670t/h all should adopt the single burner flame detector.Now, the flame detector of Chinese large-sized boiler is in the majority with imported product, because difference to the theoretical deciphering of flame combustion aspect existence, actual conditions for China's boiler combustion, in application, also has suitable limitation, this shows that mainly the debugging working condition requirement is harsh, step is loaded down with trivial details, does not often reach ideal effect.Can not satisfy the actual demand that single burner flame detects.The domestic in recent years people of having adopts camera production flame image, detect single burner flame by Computer Image Processing then, because computer image processing technology is still very unripe at present to the processing of flame image, this method also has with a certain distance from practical application.
Summary of the invention
The objective of the invention is to overcome the shortcoming of above-mentioned flame detector, the method and apparatus that provides a kind of high performance single burner flame to detect, it can distinguish the flame of target combustion device from whole furnace flame and very strong furnace wall radiation, (FSSS) be connected with " boiler furnace safety monitoring system ", make this system can really understand the combustion conditions of boiler, when detecting the fire extinguishing of burner hearth or single burner, fuel shutoff supply in time, the time that makes unignited fuel enter burner hearth shortens as far as possible, and then fundamentally prevents the generation of furnace puff accident.
Modern Theory of Combustion is thought: fuel can be divided into preheating-drying in the boiler furnace internal combustion, catches fire, burning, after-flame four-stage.In this several stages, most important is exactly the stage of catching fire.Make fuel combustion complete, at first will realize rapid and stable catching fire, guarantee the good beginning of combustion process; Also have only and realized rapid and stable catching fire, burning and after-flame stage just may carry out, and the stability of burning and efficient could improve.Therefore the detected object of single burner flame should be catching fire the stage of flame.
Theory of Combustion and experimental result all show, the most important phase that acts as a fuel and burn---the stage of catching fire exists stronger light ray radiation flicker, the energy of AC portion is very big in the flame, and the luminous energy flicker of other stage of burning and full furnace flame is all very weak, the spectrum energy of AC portion distributes also has very big difference with the stage of catching fire, that is to say that the dynamic spectrum of single burner flame is different with full burner hearth or background flame.In fact, industrial flame is not transparent, and the dynamic spectrum of a certain burner flame almost can not pass the dynamic spectrum that industrial flame removes to influence other burner flame.
The present invention adopts the method for characteristic frequency spectrum analysis to detect single burner flame, it is characterized in that catching the characteristic frequency spectrum of single burner flame at ignition zone light radiation signal of telecommunication after opto-electronic conversion, single burner flame is separated from background flame, large-sized boiler for a plurality of burners, can reject the influence of background flame, detect the flame combustion situation of target combustion device, its step is as follows:
1, flame detecting probe is installed in one to one by the target combustion device, the fire area of target combustion device fuel combustion flame is included in the visual angle of this flame detecting probe;
2, the set of lenses in the flame detecting probe (1) converts the signal of telecommunication to the whole flame optical signal transmission in the visual angle and focus on the optical-electrical converter (2);
3, above-said current signal through cable transmission to the signal processing unit A/D converter (3), convert digital quantity to;
4, above-mentioned digital quantity is delivered to the numerical characteristic frequency spectrum analyser (4) that MCU is the main body formation, making the frequency-region signal of 0~1000HZ handles, from " 0 ", by 0,40,80 ... 920,960,1000 orders, on average whenever increasing 40HZ is a frequency, and promptly handling bandwidth for the frequency-region signal of each frequency is 40HZ;
5, by on-the-spot site test debugging, if certain frequency target combustion device fire extinguishing time-frequency domain signal handle in the bandwidth energy less than, when equaling to catch fire energy 40%, this frequency promptly is judged to be the feature frequency, forms described characteristic frequency spectrum by the feature frequency; And it is stored in the memory in it, MCU carries out the energy summation operation to target combustion device characteristic frequency spectrum signal, and the value that calculates under the fire extinguishing state is the fire extinguishing judgment threshold, delivers to display (7) and shows;
6, by parameter key (6) is set, the judgment threshold input digit of will putting out a fire characteristic frequency spectrum analyzer (4), the computing of making comparisons, the fire extinguishing judgment threshold also is stored in its interior memory;
7, by parameter key (6) is set, to put out a fire and judge delay time input digit characteristic frequency spectrum analyzer (4), the computing of making comparisons, its fire extinguishing judges that delay time is stored in its built-in storage, the setting range of fire extinguishing judgement delay time 0~6 second, representative value 3 seconds;
8, numerical characteristic frequency spectrum analyser (4) with energy read group total during signal in the target combustion device flame characteristic frequency spectrum under the boiler operatiopn state, promptly obtains single burner flare up fire value, through D/A converter (5), its signal is delivered to analogue instrument again show.
The single burner flame detecting device that the invention process frequency spectrum analysis method is made, it comprises a light inspection probe and the signal processing unit be made up of set of lenses (1), optical-electrical converter (2).The technical scheme of signal processing unit is summarized as follows:
Numerical characteristic frequency spectrum analyser (4) in the signal processing unit is provided with key (6) by parallel bus and A/D converter (3) and parameter and is connected; Be connected with D/A converter (5) with display (7) by universal serial bus; Numerical characteristic frequency spectrum analyser (4), by A/D converter (3) the high speed acquisition time domain signal of telecommunication, portion is transformed into frequency-region signal with time-domain signal and handles within it, will compare, and the single burner flare up fire value that computing draws is divided three tunnel outputs:
1, delivers to display (7);
2, deliver to D/A converter (5), convert analog quantity to;
3, with threshold ratio, when being lower than, equaling threshold value and remaining to the regulation delay time, export a switching value.
Device of the present invention can the fuel band difference, adopts the light-sensitive element of ultraviolet light, visible light, infrared light to make optical-electrical converter respectively as combustion gas, fire coal, fuel oil; The visual angle of its flame detecting probe is 70 °.
Single burner flame detector of the present invention is not only applicable to the thermal power plant, is applicable to the petroleum chemical enterprise of pyrolysis furnace yet; Be not only applicable to fine coal and make fuel, be applicable to the large-sized boiler of fuel oil, combustion gas yet.
From the result that reality is used, the checkout gear of single burner flame of the present invention, low cost of manufacture, technical performance is stable, and the reliability height is a kind of of the optional instrument of boiler furnace security monitoring.
Description of drawings
Fig. 1 is a principle of the invention calcspar
Fig. 2 is a flame detecting probe structural representation of the present invention
Fig. 3 is first embodiment circuit theory diagrams of the present invention
Fig. 4 is second embodiment circuit theory diagrams of the present invention
Fig. 5 is the 3rd embodiment circuit theory diagrams of the present invention
Fig. 6 is the 4th an embodiment schematic block circuit diagram of the present invention
Fig. 7 is the present invention running experiment result curve figure on coal-burning boiler
Fig. 8 is fuel oil running experiment result curve figure of the present invention
The specific embodiment
Below in conjunction with the accompanying drawing and the specific embodiment the present invention is described in further detail:
In Fig. 2, quartz glass convex lens group (1) in the flame detecting probe, be contained in the shell (12), place the front end of flame detecting probe, flame light focuses on the photocell (15) through light pipe (13), convert voltage signal to, link to each other with circuit board (16) by lead, realize voltage---the conversion of electric current, its 4~20mA signal is delivered to signal processing unit through lead again, aviation socket (17) is adopted in outlet, to guarantee dustproof effect.Adopt installed part (14) and boiler furnace to join.Cooling is constantly blasted in the probe shell by mouthpiece (18) with compressed air, and probe is cooled off.
Embodiment 1
Signal processor as shown in Figure 3, furnace flame 4~20mA signal converts voltage signal to through R1, delivers to the A/D input AD0 of microprocessor after amplifying through operational amplifier U1 on the one hand; On the other hand by C1 isolated DC component, through receiving the A/D input AD1 of microprocessor after the operational amplifier U2 amplification.Microprocessor MCU carries out computing according to the A/D result of alternating current-direct current, draws the characteristic frequency spectrum of single burner flame, judges having or not of single burner flame.Microprocessor has three kinds of way of outputs; 1. drive charactron by U4, show operation and fault-signal.2. drive relay by triode N1, output switching value signal.3. the flare up fire digital quantity of process computing converts the output of 4~20mA current signal to by operational amplifier U5 and current converter Z2 after D/A converts analog quantity to.
Microprocessor P2 mouth also is connected to four button S1-S4, operational factor is set uses.
Embodiment 2
Signal processor as shown in Figure 4, furnace flame 4~20mA signal converts voltage signal to through R1, delivers to the A/D input AD0 of microprocessor after amplifying through operational amplifier U1 on the one hand; By C1 isolated DC component, amplify, behind bandpass filter U3 able to programme, two band signals delivered to again A/D input AD1, the AD2 of microprocessor through operational amplifier U2 on the other hand.Microprocessor MCU carries out computing according to the A/D result of alternating current-direct current, judges having or not of single burner flame.Microprocessor has three kinds of way of outputs: 1. drive charactron by U4, show operation and fault message.2. drive relay by triode N1, output switching value signal.3. process computing flare up fire digital quantity converts the output of 4~20mA current signal to by operational amplifier U5 and current converter Z2 after D/A converts analog quantity to.
Microprocessor P2 mouth also is connected to four button S1-S4, operational factor is set uses.
Embodiment 3
Signal processor as shown in Figure 5, furnace flame 4~20mA signal converts voltage signal to through R1, receives A/D converter U3 input IN after amplifying through operational amplifier U1 on the one hand; On the other hand by C1 isolated DC component, through receiving A/D converter U4 input IN after the operational amplifier U2 amplification.The transformation result of A/D converter U3, U4 outputs to digital signal processor DSP.DSP carries out computing according to the A/D result of alternating current-direct current, draws the characteristic frequency spectrum of single burner flame, judges having or not of single burner flame.Digital signal processor has three kinds of way of outputs; 1. drive charactron by MAX7219, show operation and fault-signal.2. drive relay by triode N1, output switching value signal.3. the flare up fire digital quantity of process computing becomes the output of 4~20mA current signal after the U5 conversion.
Embodiment 4
With the computer be core the detection theory diagram as shown in Figure 6, add A/D capture card and on-off output card in computer-internal.The flame probe output signal is received A/D capture card input, and computer reads the laggard row operation of A/D result, calculates single burner flame value in the characteristic frequency spectrum of single burner flame.Computer carries out screen display on the one hand, on the other hand this flame value and fire extinguishing judgment threshold is compared, if be lower than the fire extinguishing judgment threshold and kept the fire extinguishing delay time, then by digital output module output fire extinguishing switching value signal.Fire extinguishing judgment threshold and fire extinguishing delay time can pass through computer settings.
Now, along with the continuous expansion and the 670t/h of unit capacity and the increase of going up boiler participation peak regulation number of times, more and more higher to the requirement of boiler furnace safety monitoring system (or the FSSS part among the DCS) operational reliability.Because serious accidents such as detonation all might take place in the overall process that starts---operation---blowing out in boiler; especially more serious in the detonation of the explosion ratio running of ignition process to the damage of burner hearth; therefore the stability of coal dust firing is exactly the key parameter of coal-burning boiler safe operation; and its one-time detection equipment---flame detector; can have or not to make to the coal dust firing stability of single burner and flame and estimate accurately and judge that this effect in whole safety system is particularly important.
Fig. 7 is the empirical curve on No. 11 burners of a certain 670t/h boiler.In preceding 50 minutes, the pulverized coal feeder of four burners (upper and lower, left and right) adjacent with monitored burner all has one to stop restart procedure, stops to restart pulverized coal feeder process (the pulverized coal feeder rotating speed is 200 rev/mins during startup) twice for monitored burner front and back then.Figure middle and upper part curve is the recording curve of common flame detector; The curve of bottom is the recording curve of flame detecting device of the present invention.As can be seen from the figure, the fire extinguishing of 4 adjacent burners, ignition process do not have any impact to the single burner flare up fire in preceding 50 minutes, and it is very responsive to the fire extinguishing and the ignition process of the burner of two this locality, react also very fast, curve has two tangible grooves, and all there are precipitous trailing edge and rising edge in the edge, and ignition point or fire extinguishing point are clear unusually, record value during fire extinguishing is also very little, when catching fire 10%; On the contrary, this moment, common fire probe but can not correctly reflect this process, even also had reverse trend two fire phases.Simultaneously, according to the situation of scene operation, the speed of service of the pulverized coal feeder of generating plant pulverized coal boiler (feeder) is seldom below 200 rev/mins, so this single burner flare up fire has the ability whether the existence of single burner flame is made correct judgement fully.
Fig. 8 is the empirical curve on No. 4 burners of a certain 220t/h boiler.The pulverized coal feeder of monitored burner becomes disconnected powder fire extinguishing by 500 rev/mins, and then the some oil combustion gun.Figure middle and upper part curve is the recording curve of common flame detector, and the bottom is the recording curve of single burner flame detecting device of the present invention.As can be seen, this flame detecting device can be made correct detection equally to the single burner flame of fuel oil from Fig. 8.
The single burner flame detecting device of developing according to the present invention, result on trial prove that compared with prior art, the cost of manufacturing is low, the technological performance of instrument, reliability height.
Single burner flame detecting device of the present invention can be used as the boiler furnace safety guard, program control ignition system, and the primary instrument that the flame among the FSSS (comprising the FSSS part among the DCS) detects is to satisfy the demand of thermal power plant, petroleum chemical enterprise.