Radiant Image Simulation of Pulverized Coal Combustion in Blast Furnace Raceway

Availableonlineatwww.sciencedirect.com@JOURNAL OF IRON AND STEEL RESEARCH, INTERNATIONAL. 2006, 13(2): 18-21Radiant Image Simulation of Pulverized Coal Combustion inBlast Furnace RacewayWEN Liang-ying, BAI Chen-guang, OU Yang-qi, CHEN Deng-fu, QIU Gui-baoCollege of Material Science and Engineering, Chongqing University, Chongqing 400030, China)Abstract: The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundaryfor numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image process-ing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image pro-Key words: raceway; radiant image; pulverized coal combustion; temperature distributionThe numerical simulation of combustion processhas been performed .2, but there is still no suitabletemperature measuring technique for three-dimennalysis 3. Nowadays, the radiant image pro-cessing technique has been developed at home and abroad.3. The relation between radiant image andpulverized coal combustion process in blast furnaceraceway was studied in present work with this meth-od to examine three-dimensional temperature distri-bution in blast furnace raceway.1 Radiant Image and Radiant Energy ofFig 1 Schematic imaging by CCDThe three-dimensional image of flame in blast and stereoscopic image of radiation in the scope of ofurnace raceway is an accumulated result of three-di- ABCd is formed on CCd target with a resolution ofmensional temperature distribution 6. The parame- NXN. The ash level of image element (i, j)is theter that can directly reflect the image is the differ- radiant energy of media within (i, j) pyramidence in brightness, namely, ash level. The image space, which is determined by energy summation deprocessing technique can be used to analyze flame livered to CCD lens 7.with radiant energy magnitude of burning pulverizedAccording to the Steffen- Boltzmann laws, thecoal in blast furnace raceway.strength that black body radiates, Eo, is proportionFig. l shows the scheme of image taking by al to absolute temperature t by 4 power, namelyCCD in blast furnace raceway. The boundary is wallE。=aTsurface. Camera lens O have a n stereo angle of viewYHa中国煤化工anda0=5.67×10-8Foundation Item: Item Sponsored by National Natural Science Foundation of ChCNMHGnited ResearchFoundation (50374085)Biography: WEN Liang-ying(1966-), Female, Doctor, Associate Professor; E-mail: cquwen cqu. edu. cn: Revised Date: May 25, 2005No. 2Radiant Image Simulation of Pulverized Coal Combustion in Blast Furnace Raceway19el or black degree; Ei. j is emissivity at boundary Sij;ased on the Wien displacement formula, T is S is surface or wall; i, j, k are nodal point or serialinversely proportional to the wavelength of the big- number.gest energy radiated by black body, aCombining Eqn. (7)with Eqn.(4), thenaT=b(2)where b is constant,andb=2.897×10-3m·KeC·E,=4(/N)Cr,exp(=,∑,K,△)Substituting eqn. (2) into Eqn. (1), thenEbE(A,T…s)+21Ci,j,kexpK,△D)E(λ,T,A)(8)Thus, Am moves to short wave direction with increasWith consideration of the asymmetrical distriAccording to the spectrum result, the longerbution of Li, and Ki t, which results in the asyrthe wavelength, the weaker the brightness is, that metrical distribution of ash level, e. is transformedis, the radiant energy is increased with ash level.into radiant energy distribution which is determinedSimilarly, the radiant energy of pulverized coal by Ti.jburning is proportional to ash level of radiant image.C.E(λ,T,)Therefore, the relation between the radiant energyubstituting Eqn. (9) into Eqn. (8), it can beof pulverized coal burning in blast furnace raceway, obtained thatEi,j, and the ash level of image element (i, j)inC·E(A,T)=E,exp(-∑K,M△M)E(,Ts)+CCD target,ei. j, can be expressed as followsE∴,=C(4)Σ[K,Aexp(-ΣK,H△D)E(,T)△](10)here C is proportional coefficient.where Ci.=C;C/[A'(O/N2)]As shown in Fig. 1 (b), the height of the pyEqn. (10) is a general equation. Supposing thatramidal is assumed to be L at element (i, j), whichthree-dimensional temperature distribution is uni-is divided into several units with an equal height Alform in blast furnace raceway, and Ti. =Ti i,t,soIn this case, the pyramid consists of some hexane-drons marked k. If the boundary of a blast furnace.jEi,exi.j. expraceway is Sij, the projection of S,i at imaging capedirection looks close to raceway walls tiny area sec-(=2K…+△D△(11)tion.Therefore, the contribution of radiant energy 2 Numerical Simulation of Combustionin unit k to the ash level of the point (i, j)in ima-Processesging pictureIs expressed as follows:EA(Q/NΣK,△)The numerical simulation of pulverized coalcombustion in blast furnace raceway was carriedE(λ,T.,)△(5) out, in which the opportunity equations of qualityThe contribution of radiation boundary Si, to momentum, concentrationthe ash level of the point (i, j) in imaging picture is model were combined with Lagranges orbit methodEA'(/N)to describe the flows in the raceway and determineK,,△D)the track of pulverized coal. The pulverized coalE(A, Tij.s)(6) consists initially of volatile, fixed carbon and ash, inAs suming up, the sum radiant energy of (i, j) which the volatiles are separated out and burningunit projecting CCD target iswhen heated, and the fixed carbon is burnt underchemical reaction control or diffusion controlE.=E,+ΣE(7)Combining the simulation of pulverized coalhere e is radiant energy determined by Plant law, combith CCD radiaging, a systemi. e, E(A, Tii,)=eC1A"exp(-C2/AT.i. ) A中国煤化工2. In this system,area receiving radiation for every image element of the inCNMH G are considered asimaging sensor; n is stereo angle of camera lens; k known conditions, and the boundary conditions ares attenuation coefficient of radiation in medium; C1, obtained from Eqn. (10). The individual artificialC2 are Plantl constant; a is wavelength; e is ash lev- assumption is treated as request quantity in iteration.Journal of Iron and Steel Research, InternationalVol 13ComputerPCI molelCCD imaging lensig 2 Schematic of CCD image processing andpulverized coal combustion controlThe optimum value of the quantity is determined bythe adjacent degree between the accumulationeffects, in imaging manner, of radiant energy distribution confirmed by heat release through burningand by radiant image in varies values adopted. Increasing a set of imaging equipment, the radiationboundary conditions can be obtained in doubleTherefore, more artificial assumptions can be deter-mined via iteration. In the extreme case, the multiradiant image information can be used to establish aclose equation set to solve out three-dimensionaltemperature distribution.Integrating the radiant image information andthe numerical simulation of combustion in blast fur-nace raceway, three-dimensional temperature distribution and three-dimensional temperature for PCIexamined in the raceway were obtained. Supposingthat the radiant characteristic parameters distributes Fig 3 Radiant image (a)and temperature distribution inevenly in blast furnace raceway by Eqn.(10), the elcelsius degree(b)of pulverized coal combustion flameementary three-dimensional temperature distributioncan be established based on two-dimensional radiant obvious that the temperature distribution curvesimage. Using the energy conservation laws, the heat in with the brightness information of the flame ra-exchange by burning can be obtained, and can be diant image. Overall, the temperature in racewayused as known conditions to solve out the concentra- without pulverized coal is higher. Temperature istions for two-phase medium in the raceway by nu. too high in the center zone to be simulated due to themerical simulation. The distribution estimated by flame image blushing scope. The resolution temper-the radiant characteristic parameters of medium is ature is approximately 2 020 C. The results are inintroduced into Egn (10)to renew three-dimension- agreement with the actual case in blast furnace race-al temperature distribution iteratively until convergence, and then the three-dimensional temperature cOnclusionsdistribution in raceway was obtained.(1) The relationship of two-dimensional3 Numerical Results of Radiant Imageand three-dFig 3 and Fig. 4 are the radiant images with or di中国煤化工e raceway was estab-without pulverized coal in blast furnace raceway in a lishCNMHGfactory and their two-dimensional temperature dis-(2)A method is put forward for numericallytribution obtained by the numerical image pressing simulating pulverized coal combustion in blast furmethod on the basis of double colors planto It is nace raceway by radiant image processing.No. 2Radiant Image Simulation of Pulverized Coal Combustion in Blast Furnace Raceway1940Fig 4 Radiant image (a)and temperature distribution in celsius degree(b)without pulverized coal injection(3) Two-dimensional imaging technique isParticle Flows and Coal Combustion in China [A]. Proc of 3rdused to measure three-dimensional temperature dis-Intern Symp on Coal Combustion [C]. Beijing: CombustionAcademy of Mechanical Engineering Institute, 1995. 1-7tribution. The numerical temperature distributions [5] Toshiki H. The Application of TV to the Flam Detector Withare in agreement with the measured results in blastthe Quantitative Diagnosis of TVpicture [] Boiler Researchfurnace raceway.1991, 246: 8-11(in Japanese)[6 SUN Jiang, XU Wei-yong, YU Yue-feng, et al. Algorithm ofRelFlame Image Processing for Combustion Judgment [J].Thermal Power, 1997,(1): 14-20(in Chinese[1] ZHOU Huai-chun, LOU Xin-sheng. Measurement Method of [7] WU Le-nian. Principle and Application of Multi- Media and ItsThree-Dimensional Combustion Temperature Distribution inRelated Technique [M]. Fujian: Southeast University PressUtility Furnaces Based on Image Processing Radiative [J]1996 (in Chinese)Chinese Electrical Engineering College Journal, 1997, 17(1): [8] QIN Yu-kun. Heat Translation in Furnace [M]. 2nd ed. Bei1-4 (in Chinese)jing: China Machine Press, 1992(in Chinese)[2] WANG Jiu-zhi, wU Chi. Monitoring Technique of the Com [9] QIU Ji-hua, ZHANG Zhi-guo, SUN Xue- xin, et aL. Numericalbustion Status of Tuyere Zone of Blast Furnace []. AISCSimulation of Pulverized Coal Combustion in BF Raceway Injec-Technique, 1997,(5): 6-10(in Chineseurner [ j. Journal of Iron and Steel Re[3] ZHOU Zuo-yuan, LI Rong-xian. Measure Foundation of Tem-search, 1996, 8(1): 1-5(in Chinese)erature and Fluid Parameter [M]. Beijing: Tsinghua Univer [10] YU Ai-ming. Investigation of Temperature Numeralized ofty Press, 1986(in Chinese)Radiant Image Pulverized Coal Combustion Flame [D][4] ZHOU Li-xing. Recent Studies on Modeling of Turbulent Gas-Chongqing: Chongqing University, 2004(in Chinese)中国煤化工CNMHG