CN1093620C - On-line detection device for combustion condition of large boiler - Google Patents

Abstract

An on-line detector for the combustion condition of large boiler features that the visual image signals collected by fire detector are imaged by objective lens on spatial filter, the target image after eliminating interference is converged to self-focusing lens, and the light is input to splitter via coupled optical cable and divided into two paths, one path is infrared filtered and converted into electric signal representing temp., the other path is directly converted into electric signal, the AC component is flame frequency signal and DC component is fuel density signal, and the three paths are amplified and fed to autocontrol system for calculation and feedback control of the air and coal delivering amount to nozzles. The method has the advantages of low cost, accurate detection and the like.

Description

The on-line measuring device of combustion condition of heavy boiler

Technical field:

The invention belongs to the online measuring technique of large-scale fire coal or oil burning boiler combustion conditions and the improvement of device, relate to field of photoelectric technology.

Background technology:

Large-scale fire coal (or oil) boiler that is widely used in the thermal power plant is to rely on hot blast that fuel is sent in the stove by pipeline, make coal dust (or elaioleucite) be injected in the burner hearth internal combustion with certain speed by nozzle, and making burning reach optimum state by the adjustment control of wind coal (oil) ratio and jet velocity.Because the change at random of fuel quality and coal dust humidity makes the ratio of wind and fuel can not become fixed mode, so the online detection of burner hearth internal combustion operating mode then becomes the foundation that burning control is adjusted.The online detection to combustion conditions now mainly contains three kinds of modes, the one, detect fire box temperature and judge fired state, because this boiler is very big and have to organize nozzles more, measured burner hearth integrated temperature is difficult to differentiate the combustion position of each nozzle, the burning that also can't tell the undesired and whole group nozzle of single-nozzle is undesired, so be difficult to realize the burning of optimum state; Another kind of mode is to be provided with flame monitor near each nozzle; as U.S. Fu Nai company; the like product that Nike and Sweden ABB AB are produced; and Chinese ZL96235721.9 patent all adopts this mode; and this monitoring mode only has the arbitration functions of " igniting fire extinguishing "; and can't realize the measuring ability of " fired state "; and the application of this dual mode can cause the excessive input of fuel usually; imperfect combustion appears; not only cause waste; the more important thing is that the stacking energy of coal dust in the stove causes the rising of pressure; the danger of blast is arranged, and the deficiency of fuel input causes also and produces waste and reduced generating efficiency.Another kind of mode is the fuel operating mode checkout gear that MIT produces, form by CCD scanning camera, monitor and automatic control system, can analyze the tonal gradation of each nozzle flame by the scanning of CCD camera, and can observe the synthetic image of burner hearth burning by monitor, thereby the combustion conditions in the judgement stove, by automatic control system the ratio of wind and fuel is adjusted control again, realize the burning of optimum state; Because camera is the closely shooting of big visual field, and can't distinguish the distance of flame, so the fire of scurrying of the background flame of each nozzle and near nozzle disturbs, often causes the disconnected and misjudgement of erroneous judgement, thereby the degree of accuracy of detection and result of use are reduced; And the price of this device is very expensive, and it is very high to the quality requirement of each parts, for example: because can not be camera near the high-temperature region, must design the optical system of big visual field, long-focus, just can avoid the dead angle, and the heat-resisting quantity of the electronic device of the reliability of its optical system, startup scanner all need be rigid in checking up under adverse circumstances, so the present domestic use of still not having.

Summary of the invention:

The objective of the invention is to design the combustion conditions on-line measuring device that a kind of large-sized boiler is used, require its ignition temperature that can record each jet hole (T), flame flicking frequency (Hz) and fuel distribution density (ρ), utilize these data to realize the burning of optimum state by the automatic control coefficient, make it to have with low cost, make easily, testing result accurately, can carry out single detection and control, fuel savings outstanding effect advantage to each nozzle.

The designed combustion conditions on-line measuring device of the present invention is examined device and signal processor and automatic control system thereof by the Fibre Optical Sensor fire and is formed, it is arranged on fire inspection device near each jet hole, fire is examined the video signal that device collects pass to its signal processor by optical fiber cable, signal after the processing all is transfused to robot control system(RCS), wind speed in conjunction with each fuel tube, robot control system(RCS) is handled the back by analysis the feed amount of each pipeline is adjusted respectively, in the hope of reaching optimal combustion state.It is characterized in that the structure of described Fibre Optical Sensor fire inspection device is, be provided with quartzy protection window, be disposed with optical lens, spatial filter and GRIN Lens thereafter, be coupled with optical fiber cable output at the end of GRIN Lens at the front end of fire inspection device sheath; The structure of described fire inspection device signal processor is, enter Y type shunt light by the optical fiber cable input and divide two the tunnel, one the tunnel converts the signal of telecommunication to by optical-electrical converter behind infrared fileter, this is temperature (T) signal, another road visible light becomes the signal of telecommunication behind optical-electrical converter, its DC component is density (ρ) signal, and its AC compounent is frequency (Hz) signal, and this three road signal is through being amplified into automatic control system.

By as can be seen above-mentioned, the present invention adopts three variable indexs (Hz, T, ρ) that the combustion position of each nozzle is described, can not only judge " igniting fire extinguishing ", and it is more definite to the comprehensive description of combustion conditions, be more convenient for realizing the control of best combustion, can obviously reach energy-conservation and purpose that raise the efficiency; The designed on-line measuring device of the present invention is provided with fire inspection device at each nozzle, can realize the part of each nozzle is detected and control, reduces the influence of whole fluctuation; And owing in fire inspection device, be provided with spatial filter, can eliminate distant place background flame and scurry the interference of fire to detecting nearby, thereby make the result of online detection more accurate, avoided the generation of erroneous judgement and misjudgement; The present invention has advantage simple in structure, that making is easy, with low cost in addition.

Description of drawings:

Accompanying drawing is the structure and the installation principle schematic of the designed combustion conditions on-line measuring device of the present invention.1 is quartzy protection window among the figure, and 2 is optical lens, and 3 is spatial filter; 4 is fire inspection device sheath; 5 is GRIN Lens, and 6 is optical fiber cable, and 7 is Y type shunt; 8 is amplifier; 9 is optical filter, and 10 is robot control system(RCS), and 11 is air velocity transducer; 12 is the fuel automatic feeding device, and 13 is wind and fuel tube.

The specific embodiment:

Describe the concrete enforcement and the using method of technical solution of the present invention in detail below in conjunction with accompanying drawing.

Referring to accompanying drawing, the on-line measuring device of designed combustion conditions is made up of fire inspection device and signal processor thereof and robot control system(RCS), fixedly installs fire near each burner noz(zle) and examine device in boiler, and make it to aim at the flame combustion district of nozzle; Owing to when the restriction of furnace binding, fire inspection device can not directly be aimed at the jet combustion district and can only be arranged in parallel with the nozzle charging line, the visual field axis of fire inspection device is tilted, make it to aim at jet combustion district (as shown in the figure); The sheath of fire inspection device is to make with the heat-resistance stainless steel pipe, fixedly install quartzy protection window at the sheath front end, its optical axis of protection window of direct-view fire inspection device overlaps with the sheath axis, and its optical axis refraction of protection window of stravismus fire inspection device has locking angle, the protection window is made prism (as figure) can finish; Be disposed with the optical fiber cable of optical lens, spatial filter and GRIN Lens and coupling in sheath after the protection window, wherein optical lens is a fire inspection device optical system lens, and optional quartz glass is made; The effect of spatial filter is the interference of eliminating background flame and scurrying fire nearby, can select fibre faceplate or binary raster to finish, its mechanism of action is, the video of fire inspection device images in the input face of spatial filter by object lens, each picture point is pressed the distance of distance by middle mind-set limit part cloth in its output face, background flame at a distance in the picture point of center imaging with scurry nearby and fieryly block in the picture point of limit portion imaging, only keep the imaging output of the target of surveying (being the flame combustion district), then can finish the elimination of interference; Spatial filter selects for use blocking of its picture point of binary raster to be easy to finish, this is that the professional knows grasp, if select for use its method of blocking of fibre faceplate can adopt the mode of blacking or hacking, the edge portion picture point blocks also can adopt the light cage ring or dwindle into as modes such as end face or amplification imagings and finishes in addition; Can be with the GRIN Lens that glass is made with the target picture collection of eliminating after disturbing, by the optical fiber cable output of coupling, optical fiber cable also can be made with quartz material in case of necessity.The structure of described fire inspection device signal processor is, the optical fiber cable input enters the Y type shunt that fixedly installs makes light divide two tunnel (Y type shunt is an optics commonly used in the optical instrument), convert the signal of telecommunication to by optical-electrical converter (optional PIN type) behind one tunnel the infrared fileter (can by the light of the above wavelength of 0.76 μ m) through fixedly installing, this by the signal that changes of survey jet combustion district temperature (T); Another road visible light divides two the tunnel after directly converting the signal of telecommunication to by optical-electrical converter (optional PIN type), one the tunnel leads to amplifying circuit through band becomes AC compounent, another Lu Zewei DC component, AC compounent by the signal of survey nozzle flame flicker frequency (Hz), DC component is the signal of fuel distribution density (ρ), and this three road signal is sent into automatic control system after amplifier amplifies.

The course of work of the combustion conditions on-line measuring device that the present invention is designed is, the fire inspection device of aiming at the jet combustion district images in spatial filter with video by protection window and optical lens, spatial filter will be eliminated with interference video nearby at a distance, make combustion zone target picture output, converge at GRIN Lens and arrive Y type shunt through the optical fiber cable of overcoupling; Light divides a road in two tunnel after filtering, make infrared light converge at optical-electrical converter, because ultrared radiation intensity can directly reflect the height of temperature, so the signal of telecommunication that optical-electrical converter is changed out then can be expressed the variation of measured temperature (T), temperature range is 500--1600 ℃; Another road visible light divides two the tunnel after directly converting the signal of telecommunication to by optical-electrical converter, one the tunnel leads to amplifying circuit through band is called AC compounent, because fuel sprays from nozzle, the fuel particle is scattered to be lighted, cause the flicker of brightness because of the explosion of fuel particle in the moment of lighting, its flicker frequency (Hz) is relevant with AC compounent, so represent flicker frequency (Hz) signal with AC compounent, its scope is 4-150Hz; And the signal of fuel distribution density (ρ) is represented with another road DC component, is because the countless fuel particles of being lighted can form brightness peak, and many more its brightness of population of being lighted are strong more, so use the DC component relevant with brightness to represent density (ρ).This three road signal is sent into robot control system(RCS) after amplifying circuit amplifies.

Be provided with data in the robot control system(RCS) and handle and automatic program, its data processor is that each signal of telecommunication that will import is converted to corresponding analog signal and is processed into data signal.And the working rules of automatic program are, can obtain corresponding energy W=δ T according to detecting data ⁴(c is a specific heat coefficient to the heat Q=mc Δ t that (δ is a Boltzmann constant) and regional area (fire inspection device is aimed at the formed cone in combustion zone) planted agent produces, Δ t is sample time, m is a fuel mass, be the weight of positive combustion fuel population), because the quality of efficiency of combustion and fuel, hot blast temperature and air are relevant with the ratio of fuel, these parameters are enrolled automatic program just can (learn air output and hot blast temperature in conjunction with the data in the current charging line according to the data that detect by wind speed and temperature sensor, learn the transfer the fuel amount by the fuel automatic feeding device) carry out computing, and the ratio of FEEDBACK CONTROL wind and fuel and feeding (wind and fuel) speed, make W and Q reach balance.For example, all be in lower limit at Hz, T, ρ and promptly represent to extinguish, ρ is little if Hz and T are in normal range (NR), then reduce feeding speed earlier, at this moment it is excessive that ρ becomes the input of big explanation fuel, and the ρ explanation fuel input that continues to diminish is not enough, and relatively T and Hz just can obtain the feeding speed and the ratio of the best again; Thus automatic program is shown as the adjustment of constructional device to transfer the fuel amount and air output to the adjustment of feeding speed and ratio, and robot control system(RCS) can make then the burner hearth burning reach optimum state to the adjustment of control respectively of each nozzle.This section narration only furnishes an explanation for the use of present techniques scheme, the scope that does not belong to the present application content, so do not elaborate, to handle as other technical scheme such as contents such as the detection of the detection of establishment, wind-force and the temperature of automatic program and control, fuel input quantity and controls, wherein Chinese patent has been applied in the detection of pipeline powder coal flow.

Claims (4)

1. An online detection device for large-scale boiler combustion conditions, which is composed of an optical fiber sensor flame detector, its signal processor and an automatic control system. The flame detector is set near each nozzle and aligned The flame combustion area of the nozzle transmits the collected video signal to its signal processor through the coupled optical fiber, and the processed signal is input to the automatic control system. The amount is adjusted separately to make the boiler combustion reach the best state; it is characterized in that the structure of the optical fiber sensor flame detector is that a quartz protective window is arranged at the front end of the flame detector sheath, and an optical lens is sequentially arranged thereafter , a spatial filter and a self-focusing lens, the end of the self-focusing lens is coupled with a fiber optic cable output; the structure of the signal processor of the fire detector is that the optical fiber cable is input into the Y-type splitter and the light is divided into two paths, and one path passes through After the infrared filter is converted into an electrical signal by a photoelectric converter, this is a temperature (T) signal, and the other visible light becomes an electrical signal after passing through a photoelectric converter. Its DC component is a density (ρ) signal, and its AC component is a frequency ( Hz) signals, these three signals enter the automatic control system after being amplified by the amplifier. 2. The detection device according to claim 1, characterized in that, the spatial filter can be selected to have at least a binary grating or a fiber optic panel with central occlusion, wherein the occlusion of the fiber optic panel can be blackened or roughened. Way. 3. The detection device according to claim 2, characterized in that, the photoelectric converter can be selected as a PIN type; the AC component and the DC component are obtained in such a way that visible light is directly converted into The electrical signal is then divided into two paths, one path becomes the AC component through the band-pass amplifier circuit, and the other path becomes the DC component. 4. according to claim 1 or 2, or the described detection device of 3, it is characterized in that, the visual axis of looking directly at the fire detector coincides with the central axis of the sheath; Wedge angle α, which can be achieved by making the protective window a refracting prism.