Off-design Characteristics of IGCC System Based on Two-stage Coal-slurry Gasification Technology

Extended Summary正文參見(jiàn)pp.1-6Off-design Characteristics of IGCC System Based on Two-stageCoal-slurry Gasification TechnologyLIU Yaoxin, WU Shaohua, LI Zhenzhong, WANG Yang(I. Harbin Institute of Technology; 2. National Power Plant Combustion Research Center)KEY WORDS: integrated gasification combined cycle (IGCC); two-stage: coal-slurry gasification technology; off-design; systemThe integrated gasification combined cycle system pumped into the gasifier together with most of(GCC)is often operated at off-design condition which coal-slurry at the first stage to produce raw syngas.Thenhas attracted much attention. But little research has been the other coal-slurry is sent at the second stage fordone on the IGCC system based on the two-stage coal- gasification. The raw syngas enters a RSC and a CSC inslurry gasification technology which can increase the series to recover the sensible heat, a cleanup unit iscold gas efficiency and decrease the oxygen arranged downstream of the CSc to clean the rawconsumption.syngas. The clean syngas drives the gas turbine toThe model of a 200MW level IGCC system based generate power. The exhaust gas from the gas turbine ison the two-stage coal-slurry gasification technologyused to generate steam in the hrsG and the steamestablished. The effects of gas turbine load, air drives the steam turbine to produce additional powerseparation unit integrated coefficient(Xas), atmosphereTable I summarizes the operating conditionstemperature and atmosphere pressure on the performanceTab 1 Design parameters of IGCC systemof IGCC systems are investigatedThe system model covers the entire IGCC system,GasifierGasificationcomprising an air separation unit (ASU), a gasifier, a20001310capacity/(t/d)radiant syngas cooler(RSC), a convective syngas coolerPurity of oxygen /%(CSC), a cleanup system, a gas turbine, a heat recoverconcentration /%Carbon conversionHigh-pressuresteam generator(HRSG), a steam turbine and auxiliary505/10systems. Figure 1 shows the configuration of the IGCc Syngas temperatureSyngas temperature outsystem modelout of rsc/℃Intermediate-pressur 297/2.695002,3e steam/(C/MPa)℃MPLow-pressure 217/0.356 Steam turbine exhaust 91Clean syngasThe results show that gross and net electricy is firstly increased and then decreased withatmosphere temperature increasing or gas turbine loaddecreasing. The lower gross electric efficiency isTnobtained under the operation condition of higher air1--ASU: 2-Gasifier: 3--RSC: 4--CSC:separation unit integrated coefficient. Atmosphere5-Cleanup system: 6--Saturator: 7--Gas turbine: 8--HRSG:9--Steam turbine: 10--Condenserpressure has little effect on system efficiency. TheFig 1 Schematic diagram of the IGCC system model application of two-stage coal-slurry gasificationIn this model, a coal-water slurry entrained flow technology h中國煤化工 ove IGCOgasifier is selected. Air is decomposed into oxygen and system performCNMHGngnitrogen in the ASU, and the nitrogen is re-injected into The results of this stuay wiI provide rererence for designthe gas turbine combustor. The separated oxygenand operation of the IGCC power plantExtended Summary正文參見(jiàn)pp7-13Research on Systems Coupled with Gas Turbines and boilers for powerSupply Efficiency Improvement of Thermal Power PlantsLI Jianfeng, LI Bin, YAO Guofu, KOU Jianyu, ZHANG Quansheng, HUANG Haitao, SHENG JianhuaYANG DI WANg Yuan(1. Technology Development Service Center, China Electricity Council; 2. North China Electric Power University3. Inner Mongolia Power Exploration Design Institute)KEY WORDS: gas turbine; boiler unit; thermal cycle; thermal efficiency; power consumption rate; coal consumption; couplingIn order to reduce coal consumption of thermal exchanger (hTHE) to be further heated. The highpower plants, through transformation of the technology temperature and high pressure air from HTHE flows intoof aircraft engines, a new system coupling a gas turbine the turbine and expands to output work in the turbineand a boiler is proposed to reduce electrical consumption The air discharged by the turbine flowing into furnaceof the fans and the other auxiliary equipments in power chamber can be used as the secondary air of the boiler. Inplants, so the coal consumption in thermal power plants addition to driving the compressor and the first andcan be reduced at the same timesecondary fans of the boiler, the remaining work outputThe coupling system in shown in Fig. 1, describing from the turbine can be used to drive a small generatorthat most of the air is droved by the fans and flowing which can reduce plant electrical consumptioninto the low-temperature air pre-heater as the primaryTaking into account the heat balance of the airand secondary air of the boiler. At the same time, a small pre-heater, the performance prediction calculation modelamount of the air compressed by the compressor flows of the coupling system is established and theinto the high-temperature air pre-heater for preheating, performance of the system is calculated. The results ofand after that flows into the high temperature heat the calculation and analysis show that the performanceof the system is impacted by the temperature of exhaustwatergas significantly. Besides using the gas turbine to drivethe compressor and the primary and secondary fans of12e boiler, the electrical power output from the systemcan reduce the station service power consumption rate at1.64%, when the inlet temperature of the turbine is 700Cthe temperature of flue gas remains 130C and the bestvalue of the ratio of the air volume flowing through thefans and the air volume flowing through the compressoris 4.29%. In this condition, the total efficiency of thecoupling system could be improved by more than 0.5%,and the coal consumption of the power generating unitreduceg/(kW.h)ceI--Fan; 2--Compressor; 3--High temperature heat exchanger; 4--Turbine;The technology of the HTHe, the compressor and5-Furmace chamber: 6--Over heater re-heater: 7--Coal economizer:the turbine中國煤化工 e mature; and theCNMHG10-Stearm turbine; 11--Condenser; 12--Feed pump: 13-Generatorinvestment payoff period is 7.66 years for the systemFig. 1 Scheme of the systemwhose power output is 3 728kW.Extended Summary正文參見(jiàn)p419Numerical Simulation of Combustion Characteristics of a 300 Mw BlastFurnace Gas/Pulverized Coal Combined Combustion boilerWANG Chunbo, WEI Jianguo, SHENG Jingui, LI Yanqi(1. North China Electric Power University; 2. Shougang Jingtang Iron and Steel Co.KEY WORDS: coal; blast furnace gas(BFG); combined combustion boiler; two-mixture fraction; numerical simulationBlast furnace gas(BFG) produced from steel mill isa low heat value fuel, which combined with pulverizedcoal to combust in boiler is one of effective waysHowever. the combustion characteristics would bechanged greatly when compared with only pulverized858X Mixed 20% BFG緊 Mixed30%BFGcoal combustion, for example, superheaters and reheaters2米are easy to excess rated temperatures and carbon contentin fly ash will become higher, etc. All these problemslead to its limited application today. Taking a 300MWFig. 2 Mean CO concentration distribution alongthe height of furnaceBFG/pulverized coal boiler for example, the combustionWhen bfg was mixed into furnace the total flucharacteristics are simulated by means of two mixturegases volume would be increased. So, the actual stayfractions way in this worktime for pulverized coal in boiler will be shortened, andThe temperature distribution in furnace is simulated it will be more difficult for coal to combust completelfirstly, as showed in Fig 1. It shows the temperature level (see in Fig 3)in furnace is lowered obviously when BFG was mixedinto boiler. For example, the maximal temperature islowered about 81K when BFG ratio is 10% for a boilersection. Also, the top temperature becomes lower withmore bfg being mixed intoMixed 20% MBFGFig 3 Stay time of coal in furnaceNo concentration is decreased obviously when---Only coal"t Mixed 10% BFGBFG was mixed into furnace. The effect will be better- Mixed 20% BFGwith more BFG being mixed into, see in Fig 4. TheMiⅸed30%BFGtemperature level is lowered and the pulverized coal stayHeight/mtime is shortened in furnace which are the main twocauses for this phenomenonFig 1 Mean temperature distribution along the height of furnaceCO is the main component of BFG; it will play animportant role in determining the combustion in furnaceThe co distribution along the height of furnace is獻新新詳被showed in Fig 2. The maximal CO concentration appearsak. Mixed 30% BFGat burner zone, no matter BFG being mixed into or not中國煤化工44And, co concentration will be decreased with more BFGCNMHGbeing mixed into furnace. It could be concluded that coalFig 4 Mean NO concentration distribution alongburning is delayed when BFG was mixed into furnacethe height of furnaceExtended Summary正文參見(jiàn)pp20-26A Quantitative Analysis Method for the Power Plant Thermal SystemBased on graph theoryRAN Peng, LI Gengsheng, ZHANG Shufang, WANG Songling( 1. North China Electric Power University; 2. Tianjin Jinneng Investment Company)KEY WORDS: coal-fired power unit; thermal system; energy-saving analysis; graph theoryA graph consists of two types of elements, namely rule, and combined with the first thermodynamics lawvertices and edges. Every edge has two endpoints in the and the mass conservation law, the weighted diagraphset of vertices, and is said to connect or join the two adjacency matrix is deduced. Thus the weighted diagraphendpoints. An edge can thus be defined as a set of two adjacency matrix can be expressed by:vertices. Alternative models of graphs can be existed inAa+A,a+Aar+△qr=r(1)the form of a Boolean binary function over the set ofThe weighted diagraph adjacency matrix is ofvertices or as a square( 0, 1-matrixBased on the meaning of graphs and the analysis of standard and concise form, whose physical meaning iswell expressedthe structure features of power plants, graph theory isA fuel differential change equation is deduced asintroduced in the thermal economy analysis to putdHo=-t d(M[Ah,J-dIIforward the abstraction rule of a power plant thermalsystem. According to the abstraction rule of a powerd(m can be expressed bylant 's thermal system, the boundary delimitation of ad(m)=-[()'(, da p +a darp +dAqp )] (3)power plant thermal system is determined, which can bed(Ii) can be expressed by:seen in Fig. 1.d()=daa[ha-h,)An example is given to illustrate the validity of themethod. and it is indicated that the thermal economicsdiagnostic method is well defined and easy to be used inCOndenssystem design and operation diagnosis. Tab. I showsoriginal datum of the main thermodynamic systemTab. 2 shows original datum of auxiliary steam-water;Calculation results are summarized in Tab. 3Tab 1 Original datum of the main thermodynamic systemFig 1 Diagram of the boundary of a coal-fired power unit'sHeater N(kJ/kg)y/(kJ/kg)thermal system24654The power plants thermal system is expressed as156.20he form of graph theory, which can be seen in Fig. 2,2391.5and it can also be simplified as shown in Fig. 3.2425.0der Condenser2527.171.10122.53830Main steamFig 2 Diagrammatic representation of the thermal system basedTab 2 Original datum of auxiliary steam-on graph theoryIn this paper, all constraints which involve multi-g-g+chain cascaded reservoirs and active power balance are_9+-MAdjusting moduleAdjusting moduldynamichandled using the heuristic strategies without any penaltynamIe balance constraintfactor. An effective method for adjusting feasible waterdischarge rate is implemented to handle the reservoirstorage volumes constraint. This method can adjust waterdischarge rate based on feasible water discharge ratesdiagram of this method is shown in Fig. 1. It ensures thati me @- mi 4e. 27 ;i mrmbeamzt Module 2and feasible storage volumes. Then the storage volumeusting module 1an be modified and the constraint is satisfied. Theeach solution in the generation satisfies the reservoirstorage volumes constraint. And it also makes the searchdescending order(FtL, "" nfor optimal solutions more conduciveo..0 eaMC s! i ad ee a y End se time wiaThe simulation is carried out on a hydrothermal中國煤化工system with the total capacity of 2975 Mw. The resultsCNMHshow the feasibility and effectiveness of the heuristicconstraints handling strategy. Moreover, the results ofFig. 1 Method of handling volume constraintExtended Summary正文參見(jiàn)pp36-41lExperimental Investigation on Co-firing of Coal andRefuse-derived Fuel in a Pilot-scale Circulating Fluidized Bed CombustorBAI Jisong, YU Chunjiang, LI Lianming, LI Xingliang, WANG Qinhui, LUO Zhongyang(Zhejiang University)KEY WORDS: refuse-derived fuel; coal; co-firing; circulating fluidized bed; pollutant emissionAs a new technology to utilize Msw for energypurpose, refuse-derived fuel(RDF)has attracted a lot ofattention worldwide. Moreover, the mode of fluidizingcombustion is considered to be a promising technologof transforming wastes into energy. In the present study,魯Coal(880℃co-firing of coal and RDF is investigated using aCoal+RDF(880℃the平Coal+RDF(950℃)circulating fluidized bed ( CFB)combustor.From TGA experiments, it can be seen that duringthe co-firing process, coal and RDF can largely maintainFig. 1 Temperature profiles along height of the combustortheir own combustion characteristics, while the addition of1600RDF significantly improves the combustion performanceCoal+RDFof coal. The combustion characteristic temperatures of1200coal, RDF and the blend are given in Tab. 1Tab 1 Combustion characteristic temperatures ofcoal, RDF and the blendSamples T:℃Tmx℃ Tmay/℃Tmx℃TeCO NO N20 SO2 HCIFig 2 Comparison of pollutants emission betweencoaH+RDF291342487550627coal mono-combustion and RDF co-firingDuring CFB experiments, the mixture fuel of RDFAs shown in Fig3, the bed temperature hasand coal can achieve stable combustion in the furnace significant impact on pollutants emission. Duringand the temperature does not fluctuate sharply with time. co-firing conditions, the higher temperature would leadyn in Fig. 1, during coal mono-combustion, the to much lower CO emission. However, with the increasetemperature in the dense bed is higher than that in the of the bed temperature, not only the conversion of fuelfreeboard to some extent. However, when RDF is N/S/Cl to gas pollutants is increased, but also the sO2co-fired, the large amount of volatile released is blown to and HCI removal reactions by Ca-based substances arethe upper part of the furnace by primary air. And the inhibited, therefore, the NO, So2, HCl concentration insubsequently intensified combustion leads to the increase flue gas is increasedof temperature in the freeboard. Therefore, compared tocoal mono-combustion, co-firing makes the axial830℃圖880℃temperature distribution more uniformAs shown in Fig. 2, the addition of RDF reduces theCO, NO, N2O, SO2 emissions, but it greatly increases theHCl concentration in flue gas. Further calculationindicates that there must be some synergistic effectsrelated to gas emissions. The Ca-based materials中國煤化工contained in RDF can remove SO2 through sulfateCNMHreaction, while the presence of HCl promotes this kind ofFig 3 Effect of the bed temperature on pollutantsdesulfurization reactionemission during co-firing testsExtended Summary正文參見(jiàn)pp42-48Operation Characteristics of Fluidized Bed Heat Exchanger of Large-scaleCirculating Fluidized Bed BoilerZHANG Man, WU Haibo, SUN Yunkai, LU Qinggang(1. Institute of Engineering Thermophysics, Chinese Academy of Sciences; 2. Graduate University of Chinese Academy of Sciences)KEY WORDS: fluidized bed heat exchanger (FBHE); circulating fluidized bed( CFB)boiler; furnace temperature; steamtemperature; operation characteristicsWith the increasing of boiler capacity, the heating working ability of the primary steam is increasedsurface area is required to control the furnace correspondingly its parameters is improved, and the heattemperature. There are various heating surface types, transfer in the FBhE is enhanced, so that the heatsuch as external heat exchanger(FBHE), Q2 type heating transfer coefficient can be increased. The heat transfersurface, platen heating surface, and so on. The heat coefficients of MTS I, MTS IL, HTR and LTS in FBHEtransfer coefficient of FBHE is calculated and analyzed. are 262, 302, 240 and 253 W/(m"K)respectively atThe test of operational characteristics of FBHE is carried 100%BMCR loadout on an actual 300Mw cfb boiler. Each Fbhearranged near the back of furnace is also divided intothree chambers. The first chamber is empty. MTS I isarranged in the second chamber and I MTS ll is arrangedin the third chamber. Front view of fbhe is showed in一 MTS IIMTS IBoiler load/%BMCRFig. 2 The heat transfer coefficient of heat surface in FBHEFig 3 indicates that the furnace temperature of aCFB boiler with FBhE is quite even along the heightdirection, and there is almost no change in temperatureFig 1 Front view of FBHEwhen the boiler operates at above 60% BMCRAccording to thermocouple and pressure gaugeThe results also indicate that the opening of conereadings, the steam enthalpy, which is at inlet and outletvalve increases monotonously along with the boiler loadof each FBHE, can be obtained. Meanwhile superheatedincreasing. In the condition of constant load when thesteam flow can be measured and calculated by a feedbed temperature rises, superheater water spray andwater flow meter and a desuperheating water flow meterreheater heat absorption will be decreased slightly. Atdifferent boiler loads, the heat transfer coefficient isof the boiler. Reheat steam flow can be obtained by the different for different heating surfaces in FBHE, whichturbine thermal balance calculation The absorbed heat ofwill be increased monotonously with the increase in theeach FBHE can be calculated according to the measuredboiler loadenthalpy increment and flow, and then the heat transfer900coefficient of each heating surface can be calculatedthrough the formula (1)and the formula(2)840(1)H△t-36%BMCR -+ 70%BMCR720%BMCR→83%BMCR◆92%BMCR△tT-7)6中國煤化工The Fig. 2 shows that heat transfer coefficietCNMHGeach heating surface increases with the boilerFig 3 Furnace temperature distribution of CFB boiler withincreasing. Because with the boiler load increasing, theFBHEExtended Summary正文參見(jiàn)p4955Analysis on Stress State of the Steam-side OxideScale in Superheater TubesHUANG Junlin, ZHoU Keyi, BIAN Caixia, XU Jianqun(Southeast University)KEY WORDS: superheater; steam-side; oxide scale; exfoliation; steady-state; stressFailures of steam-side oxide scales in highickness of the effective tube walltemperature components of boilers, such as superheaterand reheater tubes have serious effect on the safety ofSteamthermal power plants. The overlarge stresses may lead tothe failure of oxide scale. Due to the difficulties inon-line monitoring and measuring, numerical methodsfor seeking the solution of stress conditions in oxidescales are widely adopted2In order to analyze the steady-state stresses in oxideFig. 1 Schematic for multi-layered hollow cylinder modelscales during the shutdown process of supercriticalTab. 1 Different calculation casesboilers, temperature field profiles in the T91 tube wallCasedo/mmLoad/%and the oxide scale are firstly obtained using the heattransfer resistance model; and a multi-layered hollowcylinder stress model, which takes into consideration of10.0the significant influence of temperature on coefficients0.15100→3010.0of thermal expansion, is subsequently developed. The150heat transfer resistance model can be simplyprogrammed using the equations listed asd+26d-26h, r(d-28,Lh, TDL 2rko L 2rhmer L (1)d+2680Load/%T=T;+RStress/MP∑R(where, hs is the steam-side heat transfer coefficient; hg isthe gas-side heat transfer coefficient influenced by bothconvection and radiant heat transferFishows the multi-layered hollowmodel. Four cases, as listed in Tab. 1. are calculatedCase 1 is the initial case. Other cases calculate theoxide scale intstresses in the steam-side oxide scale when the operation340134413.4813.52condition changes from Case 1 to the current condition(b)Case 4Fig. 2 shows the calculation results of hoop stresses.on of hoop stress in steam-side oxide scaleThe calculation results show that lacould notThile for a low thermal loadccur in oxide scales during the shutdown process中國煤化工ected. AccordingRadial and circumferential crack are the possible failure to practicalCNMHGmodes. In order to mitigate the failure of oxide scales, rates may be adopted to relieve stresses in oxide scalesfor a low steam temperature in Case 2, the thermal loadby creating microcracksExtended Summary正文參見(jiàn)pp56-6Working Character of Multi Nozzle steam-liquid Two-phase ejectorsMA Xinxia, YUAN Yichao, HUANG Ming, LIU Yuzheng(1. University of Shanghai for Science and Technology; 2. Shanghai Institute of Quality Inspection and Technical Research)KEY WORDS: multi-nozzle ejector; steam-liquid two-phase flow; volume entrainment ratio; homogeneous equilibrium modelsub-cooled water; drynessDuring the past few years, much work has beenFig. 4 shows the effect of pressure ratio on volumedone on the study of the steam-liquid jet technology, entrainment ratio under different cross section of themainly focusing on the supersaturated steam and the ejector m, when the steam dryness x is 0.35 andsuperheated steam in terms of the research of working sub-cooled water temperature ty is 10C. It is noticed thatsteam; however, the wet steam in steam-liquid jet volume entrainment ratio decreases with the increasingtechnology has been paid little attention. In industrial of pressure ratng of cross sectiapplication, wet saturated steam with certain dryness is the ejector can increase volume entrainment ratio but cutoften used as low-pressure stream. Therefore, a down the working range of the ejector. The volumeone-dimensional theoretical model has been built to entrainment ratio decreases with the increasing of thecalculate the performance data of a multi-nozzle steam dryness and sub-cooled water temperaturesteam-liquid two-phase ejector by the equations of mass,energy and momentum conservation for calculation ofWorking steamSteam nozzle/Ledger platemechanism of the multi nozzle steam-liquid two-phaseCold waterejector with wet saturated steam as the working fluidThe critical velocity of the single steam nozzle is再Outer sleevecomputed by the homogeneous equilibrium model ofConical section oftwo-phase critical flow and amended by the multi-steammixed spoutnozzle speed coefficient, and then the exit velocity of themulti-steam nozzle is obtained and the resistance of theInhalation roomColumn section ofmixing section is determined by integrating Cattadori'smixed spoutwall forces model and Howards"throat pressure lossDiffuse spoutheory, which is calculated by using Eq (1)and (2)Fig 2 Schematic of experimental elementVsI=aV0.841a,(3m()+Ba)4n+A1-4),a3220.15In order to verify the proposed model, a set ofc0.10experimental facility has been designed with wetsaturated steam as the working fluid, as shown in Fig. 1Fig 2 illustrates the multi-nozzle ejectorExperimentexperimental unit, which consists of seven steamnozzles. a subcooled water inhalation room and seven0.10.20.3Hmixing spouts and diffusing spoutsFig 3 Comparison between computational values andvahe g 3 shows the result of comparing computationalvalues with experimental results about influence oferimental results about influence of pressure ratio on volumepressure ratio on volume entrainment ratio. It can beentrainment ratio(x=0.48, t=50C)seen that computational results of volume entrainmenratio agree well with the experimental datam=6.5Dry saturatedsteamm=2.5steamHFig 4 Influence of pressure ratio on volume entrainment ratioFig. 1 Experimental system for multi-nozzle steam-water ejector(x=0,35,t=10℃)tended Summary正文參見(jiàn)pp65-70Numerical Simulation on Mercury Emission and Transformation ofOccurrence State in a 410t/h Coal-fired boilerZHANG Hairu, WANG Meng, WU Hao, YANG Hongmin(Nanjing Normal University)KEY WORDS: coal-fired boiler: release and transformation of mercury; detailed kinetic mechanism; numerical simulationCoal-fired power plants are major point sources of mercury compounds are in unsteady thermal state andmercury discharged into the atmosphere. Both elemental the transformation of mercury occurs(see Fig. 2)and oxidized mercury are emitted to the air from2200combustion point sources. The oxidized mercury can beremoved easily by conventional pollutants control1600equipment of coal-fired power plants as a result of thehigher solubility in atmospheric moisture. On thecontrary, elemental mercury is volatile and has notendency to associate with any solid substrates. Thus,下wkmercury cantransported over long400ces. It is important to understand the behaThe path of flue gas/mmercury releasing and transformation However, theFig 1 Distribution of temperature and elemental mercurycomplexity of mercury chemistry and the variability ofMole fraction of Hgcoal types and boiler configurations make it difficult toexplain this transformation in the devices of coal-fired374.221×10湖333.862×10In order to obtain and explain the characteristics of293.503×106releasing, distribution and transformation of mercury in253.144×10furnace and downstream flue gas pathway of a 410t/h212783×10tangentially coal-fired boiler, it is necessary to172.336×106understand the chemistry of mercury in flue gas and the131.977×10potential physical and chemical interactions at various91.618×10points in the system. The numerical simulation based on1259×106the detailed mercury kinetic mechanism and the Eddy9000×107Dissipation Conception(EDC)model is carried out inthis paperThe reaction mechanism applied in our work isFig. 2 Mole fraction of Hg0 of longitudinal section of the systemconsisted of 32 element reactions, mainly including threeAuthors also have a conclusion that HCl is crucialtypes: eight element reactions of mercury and chlorineed by widmer, six basic element in the mercury oxidation process and HOCl is thereactions from Xu Minghou and 18 element reactionsimportant specie which oxidizes elemental mercury. Byontrast, the oxidized mercury is the main form and therelating element chlorine and mercury from Sliger. Theequations of reactions are RI-R8, R9-Rl4 and RI5-R32hlorine plays an important role when temperature isbelow 900K. The concentration of mercury chloride isrespectively.The simulation resultsthat withabout 92.36% and that of mercuric oxide is 7. 64%. Thedecreasing of the temperatureoxidation process occurs in the convection flue and thegas along thedownstream, the mole fraction of elemental mercuryconcentration of mercury chloride increases rapidly asreduces dramatically(see Fig. 1). The mercury is mainlythe temperature dropsreleased in the furnace close to the zone of burners中國煤化工 ing method,thewhere the pulverized coal is injected and the mainsimulationCNMHGthe experimentaloccurrence state of mercury is elemental mercury There measurement data conducted by other investigators, theis a critical temperature between 700-800 C, where most results indicated both data are in good agreementS10Extended Summary正文參見(jiàn)p7175Simulation for the flow field of the turbulence coalescence device andthe Trajectory of ParticlesLIU Zhong, LIU Hanxiao, FENG Xinxin, ZHANG Weifeng, LI Huailiang, XING Zhenzhong(North China Electric Power University)KEY WORDS: ultrafine particle; coalescence; flow field; particle trajectories; numerical simulationThe strengthened collection of ultrafine particleswill be a new direction of dedusting technologycombining fluid mechanics aggregation with bipolar; the(a)5m/sresearch group develops a particles aggregationtechnology and invents an aggregation device. In thispaper, the numerical simulation is used to study the flowfield and particle movement in the device(b)10 m/sThere are three channels in the turbulence deviceand each channel has the same number of vortex bodiesin this paper, we only study one channel which is shown(c)12m/sin the box of Fig. 1. The length of the turbulencecoalescence device is 1 800mm and the width is 110 mmLarge vortex body Small vortex body(d)15m/sinletFig 2 Particle trajectories under different speedsFig. 1 Sketch of the turbulence coalescence device8.10×10The main forces which have an effect on the6.20×10particle are Saffman force, fluid viscous drag andcoulomb foconservation equations are set up; and the conservationequations of particle and fluid are coupled so as tocalculate the particle trajectories in the deviceFig 3 Moving trajectories of different size particlesThe particle movements in the condition ofFig. 4 shows that the charged particles gather in thefferent flow velocity, diameter and charging/withoutiddle of the device. the turbulence effect is intcharging are displayed as below:behind the small vortex body, and the particle tracFig 2 shows that the turbulence effect on thechange to be more complex. The attractive force betweenparticle is the weakest when the flow velocity is 5 m/sparticles increases as the particles are charged, whichmost particles move along the primary direction; and thewill facilitate the collisions and coalescenceperturbation only can be found at the end. With theincrease of the flow velocity, the turbulence effect wilbe enhanced. The particle trace crossing is obvious. Thehigher the velocity is, the more obvious the tracecrossing phenomenon is. The crossing means that theparticles may collide with each other, and the collidingrate is proportional to the flow velocity中國煤化工Fig 3 shows that large particles are less affected byCNMHGthe turbulence, compared with the small ones, so there isFig 4 Moving trajectories of not charged particles andan apparent relative motion between themharged particlesExtended Summary正文參見(jiàn)pp7681Experimental Study on Flow Characteristics inRectangular and Circular MicrochannelsZHONG Zhuhai, LIU Lei, FAN Huiqing, ZHANG Xiang(XI'an Jiaotong University)KEY WORDS: friction factor; wall roughness; Poiseuille number; flow resistance; local resistanceThe flow characteristics of the microscale often250 r Experimental dataD=1948pmdeviate significantly from conventional theories, such asD=1919mvD=1733mthe friction factor () the transition Reynolds number1504a=1674the Poiseuille number(po), etc.Laminar theoryIn ordlicability of the±20%conventional theory, the friction factor and the poiseuillenumber are given by the conventional theory=2a4(1)(b)Po versus ReP=96(1-1.3553a+1.9467a2-1.7012a3+Fig 1 Flow characteristics of rectangular microchannels0.9546a4-0.2537a3)0.18where the experimental value of the friction factor f isderived by the resistance prediction model. The theoretical0.10D=357 umvalue of the friction factor in laminar regime is■D=168um20%P0.06Re0.04In the turbulent zone the theoretical value offriction factor isf=03164/Re3Re/1032Fig I and Fig. 2 show the friction factor and thePoiseuille number as a function of the Reynolds number250The resistance prediction model obtains the★Dh=399umexperimental friction factor with the Reynolds number in■D-168mrectangular microchannels with the hydrodynamic1 50[ Laminar theoryP=64diameter(Dh) of 167 um to 195 um and circularmicrotubes of 168 um to 399 um. Their results arecompared with those obtained from the theory flow. agood agreement is found over the friction factor and thePoiseuille number of both the rectangular microchannelD=1919umFig. 2 Fow characteristics of circular microchannels△D=1674umand the circular microtube; and the critical Reynoldsfamma-58/Renumber falls between 1 300 and 1 480 in rectangularmicrochannels while between 2 600 and 2 850 in circular中國煤化工fd0.3164Re2and the floyCNMH Gn microchannelsshows that theoretical curves agree well with the(a)versus ReS12Extended Summary正文參見(jiàn)pp82-87Inversion of Temperature-dependent Thermal Conductivity Based onTransient Inverse Heat Conduction ProblemsCUI Miao, GAo Xiaowei. LIU Yunfei(Dalian University of Technology)KEY WORDS: inverse problem; transient heat conduction; temperature-dependent thermal conductivity; complexvariable-differentiation methodThe inverse heat conduction problems have number. The results show that with the growth of thereceived considerable attention from many researchers convergence factor, the total iteration number increasesusing a variety of different methods, which have beenwidely employed in dynamical engineering, aerospaceand metallurgy. The inversion oftemperature-dependent thermal conductivity belongs toinverse heat conduction problemsThe methods for solutions of the inverse heatconduction problems can be classified into stochastictypes and gradient types. The stochastic methods such asgenetic02040.60.81.0gorithmConvergence factorcomputational efforts. In a gradient method, thedetermination of the sensitivity matrix is essentialFig. 1 Effect of convergence factor on total iteration numberHowever, the sensitivity matrix is always difficult to beTab 1 shows the effect of the temperatureprecisely calculated.measurement errors on the inverse resultsIn order to deal with the difficulty of thedetermination of the sensitivity matrix, the efficientTab 1 Effects of measurement errors on inverted resultscomplex-variable-differentiation method is introducedThe main related equations are as followsTeX of a reaf(r) is replaced by a complex one x+ih, with a small0.3710.7541.153imaginary part h very small (usually h=10-2).The03130958functionf(rti)can be expanded into Taylor's series as3000889hf(x+ih)=f(x)+if(x)-f"(x)+o(h3)(1)0.1965000.00700190.036Since h is very small, Eq. (2)can be obtained0.875f(r)Imf(x+ih]0.0260072h0.1410243where, Im denotes the imaginary part0340In the present work, two kinds of materials known0.711as fiber and steel, which have temperature-dependent1100085817022.532thermal conductivities, are tested. Numerical examples1.196are given to show the effectiveness of the method. TheIt can be seen that the algorithm can represent theprior information of the functional form of the thermal effects of the measurement errors The inverse error willconductivity is not necessaryincrease with the increase of the measurement errors. InThe effect of convergence factor on total iteration addition, mos中國煤化工 less than thenumber and the uncertainties of the measurement errors measurementHCNMH Gccurate resultson the inverse results are also investigated. Fig. I shovcan be obtained with certain measurement errors and thethe effect of convergence factor on total iteration inverse approach is robust.Extended Summary正文參見(jiàn)p8894A Modified Analytical Model to Calculate Temperature Distribution ofGas Turbine Blade and the Cooling Air requiredLIU Shangming, WEi Chengliang, PU Xingxing, ZHANG Wer(1. Dalian University of Technology; 2. Liaoning Electric Power Dispatch and Communication Center)KEY WORDS: gas turbine; blade cooling; temperature distribution; modified analytical modelDistribution of cooling air required by gas turbine Stanton number. Then a cooling level parameter throughblades is important, and the design values are strictlynversion, which could be estimated by empiricalconfidential. Therefore it is difficult and necessary to experience, is taken as the blade internal cooling channelestablish an accurate model that can calculate the coolingair flow and the temperature distribution of the bladeThe temperature distribution expression Tbo() ofsurtacesthe outer surface of the metal blade along the altitudeThe traditional model and the semi-empirical model direction is shown in Eq (2). We consider the minimumfor calculating the cooling air have shortcomings, and amount of cooling air is available when the cooling aircannot meet the needs of research. Based on advantages required that ensures the maximum temperature of theand disadvantages of the previous models, a modified outer surface of the metal blade does not exceed theanalytical model is proposed. As shown in Fig. 1, the maximum allowable temperature Tg, max. After setting theblades are taken as a cross-flow heat exchanger in this value of Tbg. max, we can gain the cooling air amount bymodel. Considering the film cooling and TBC, the blade the iterative calculation methodis divided into N infinitesimal elements along chordTb()=ac(1+ Bitbe Bibw) -Te)]Then the temperature distribution expression Tc ()of(2)Bite[ae(1+ Bi be Bibw)+the cooling air along the altitude direction is obtainedbased on the principles of thermodynamics and heataccording to the result of calculation, the ratio oftransfer, as shown in Eq (1)the cooling air required of nozzle and the nozzle s inlet△Sdygas flow is 7.8%.The ratio of the cooling air required offlow is 4. 4%.Thetemperature distribution of the outer Blade surface alongthe altitude direction of the first nozzle raw is shown inFig 2, revealing exponential distribution roughly. Theresultsin conformity with theliterature data, which means that our model has a highaccuFig 1 Schematic diagram of infinitesimal element of bladen()m=(-,y)=0-y)NTU1070HHTo obtain the equations of T), the number ofNTU, which is related to fluid and material properties as中國煤化工I.0well as blade internal cooling parameters, should beCNMHGresolved. In this paper the heat transfer coefficients bothFig 2 Temperature distribution of the outer blade surface alongin the gas side and the cooling air side are derived fromhe altitude direction of the first nozzle raw14Extended Su正文參見(jiàn)pp95-102Dynamic Characteristics of Rotating Stall for Centrifugal FansZHANG Lei, WANG Songling, ZHANG Qian, WU Zhengren(North China Electric Power University)KEY WORDS: centrifugal fan; rotating stall; dynamic characteristics; throttle valve modelRotating stall is a common phenomenon causedP-()=P4+2k(1)faults, which will destroy the impeller flow fieldresult in fracture of blades on the high stress pointsThe numerical results show that the stall inceptionstudy on the mechanism of rotating stall is of important presents a significant modal waveform, which can besignificance to prediction and active control of rotating developeda stall cell in 50 rotating periodsstallPropagation velocity of the stall cell is 62.9% of theig. 1 shows the geometric model of the rotor's rotating speed Stall frequency of the fan is 14. 15 Hz,G4-73No 8D centrifugal fan, including the inlet and which agrees well with experimental resultsoutlet tubes, a current collector, an impeller and a voluteThe characteristics at four typical times before andThe characteristics of the centrifugal fan are described after the appearance of rotating stall are analyzed. Afterby the continuity equation, unsteady Reynolds the appearance of rotating stall, the flowrates through alltime-averaged Navier-Stokes equations and the impeller passages are redistributed; some florws areRealizable k-s turbulent modeldecreased and others are increased with the applicationof the low-flowrate centrifugal fanthe analysis of flow field, thecircumferential propagation law of the stall cell isstudied. After the occurrence of the rotating stall, severalblade channels are blocked, leading to the decreasing ofthe incident angle of the adjacent blade along theimpeller rotating direction. Whereas the incident angle isincreased and the flow capacity is reduced until the flochannel is blocked at the adjacent blade in the inverseFig 1 Geometric model of centrifugal fandirection of impeller rotation in contrary. The rotatingig2 shows the stall model of the fan system direction of the stall cell is opposite to the impeller in theincluding the fan and the throttle valve. The operating relative coordinate system. When blades pass through thepoint is determined by the intersection of the fan stall cell, they suffer alternating stress that may causeperformance curve and resistance performance curves. fatigue fracture and influence safe operation of the fanWhen the valve opening is gradually decreased, theResults show that the fluctuating curve of fullvolume flow will be reduced, with the movement of the pressure is similar to a sine curve at the stall region, andoperating point from a to b and c, and the occurrence of the time difference between adjacent peaks is just a stallrotating stall. The throttle valve located at the fan's outlet cell rotating period. It can be indicated that full pressureand outside environment, and the mathematical relation mainly depends on the fluid provided by impelleramong them is determined by the throttle valve function, channels far from the outlet when the stall cell is close toas shown in equation (1)the volute tongue. As the stall cell rotates clockwisethrough the volute tongue region, the high-energy fluidprovided by other impeller channels tends to be closer tothe outlet; and full pressure of the fan gradually increasesuntil reaching the maximum level when the stall cellturns to the中國煤化工 volute tongue.Flow field anCN MH Gure fluctuationand its frequency are determined by relative position andFig 2 Fan system stall modelpropagation velocity of the stall cellExtended Summary正文參見(jiàn)pp.103-108Hydraulic Decoupling and Nonlinear Hydro Turbine Model with SharingCommon ConduitZENG Yun, ZHANG Lixiang, GUO Yakun, DONG Hongkui'(1. Kunming University of Science and Technology; 2. University of Aberdeen3. Yunnan Electric Power Test and research Institute)KEY WORDS: hydraulic coupling; decoupling; additional disturbance; hydro turbine; nonlinear modelThe influence of a hydraulic system on a hydro hydraulic coupling produced in common conduit is takenturbine is demonstrated by the change of water head and as additional input control. Therefore, the order of thesystem with a sharing common conduit, its core problemEquivalent penstock parameters are definedis the hydraulic coupling in the sharing conduit, whichTO=ToI ToTcomplicates the object model and makes it difficult totake account of its influence. The current appliedhydraulic system model is a transfer function, which isinconvenient in nonlinear analysis and control design. InAt last, the motion equation of main servomotor isthis paper, the hydraulic dynamics is transformed into a added to compose the nonlinear hydro turbine modelnonlinear differential equation model, and the decoupledx=f(r)+gu+w242+w393hydraulic coupling is taken as additional input of thedifferential model. In this way, the nonlinear hydroturbine model can be directly connected with thexdifferential equation model of the controller and thegenerator, thus applied to nonlinear analysis and controlx2[-(n+f1+)xdesignf(x)=The hydro turbine dynamics is decoupled as Fig. 132x2+[h-(+f+-2)x2ZoTox5-y)In order to simulate the operation characteristics ofGD(controller, the model proposed in this paper is combinedwith PID governor and PI excitation controller forFig 1 Decoupling of hydraulic couplingsimulation. Simulation result is shown as Fig. 2Dynamic head is expanded as follow:1.14ha (s)=ZortT,s+T3s1.122. Decoupled model, ignored frictior2+4294()(1)1.103. Decoupled modelFrom above formula(1), the hydraulic dynamics1-14. Decoupled model,transformed from transfer function to differentialignored couplingequation in relative value. In this procedure, a keyequation10203040q1=-yvh1(2)Fig 2 Co中國煤化 Tg different modeThe hydraulic system wit sharing common conduitThe sirCNMHGis decomposed into an equivalent one penstock and onelarge error, and the methodmachine model with additional input. Decomposed the proposed in this paper is effectiveS16Extended Summar正文參見(jiàn)p109-115Effects of Inlet Setting Angles of Space Guide Vanes onSubmersible Pump PerformancesWEI Qingshun, LIU Zailun(1. Shanxi Agricultural University; 2. Lanzhou University of Technology)KEY WORDS: space guide vane; inlet setting angle; submersible pump; perfoce curve;numerical analysis; computational fluiddynamics(CFD)A circulating pump is an auxiliary machine in aan o)Fig 1 Flow chart of the improved HCS methodThe improved HCS method will restart to searchnew MPP when wind speed changes again followinghalted perturbation. It detects the variation of wind speedby equation (2) and restarts searching with theperturbation step defined as equation (3).△ak)=0and△P(k)>B(2)Improved HCSConventional hcs△a4(k+1)=△anm=sign(△P(k)b(3)Where B is the positive threshold, and b is the positiveC-Wrong searching directions determined bythe conventional hCS methodAs illustrated in Fig. 2, the improved HCS methodFig 2 Rotor speed of improved HCS andcan halt at MPP when wind speed is stable and theconventional HCS with variable-step sizedisturbance to determinations of searching directions of detection and halt at MPP. Thus. the mechanicalcaused by wind speed variations is eliminated. Moreover, damage to wind turbines around mPP caused by rotorthe efficiencies of the different Hcs methods undersp中國煤化工due. oreover,several wind conditions are listed in Tab. 1followingThe improved HCS method not only inherits the determinatCNMHG caused by windadvantage of variable-step HCS method so that MPP can speed variations is eliminated and as a result more windbe rapidly reached, but also introduces the mechanisms energy is captureds20