Hybrid Simulation For The Combustion Characteristics Of600MW Supercritical Unit With W-flame Furnace And The Distributed Parameters Of Waterwall

The large capacity and high parameters supercritical (ultra-supercritical) unit is theleading direction of the development of coal-fired generating units both at home andabroad，advantages of improving the efficiency of coal-fired electricity and loweringpollutant emissions. The structural design of W-flame is helpful to the stablecombustion using lean coal and anthracite coal. Therefore supercritical W-flame boilerenjoys its unique advantages in improving boiler thermal efficiency and energyutilization.Currently the supercritical W-flame boilers which has put into operation in ourcountry exist stability problem under the high-level load situation, highly fly ashcombustible content, easy slaging in the down-furnace and high NOx emission. To solveproblems above,and to improve the supercritical W-flame boiler unit in operation andtheir management level, the research in order to understand the distributioncharacteristics of combustion in the furnace through numerical simulation method toestablish the furnace turbulent flow, heat transfer and combustion model has importantguiding significance for optimal operation and improvement of design.This paper takes the600MW supercritical W-flame boiler which is designed byDongfang Boiler Group as the research object. The CFD simulation of the furnace understeady basic operating conditions, different load conditions and unsteady trans-criticalconditions have been studied using computational fluid dynamics methodsFollowing aspects are included in the paper:1. The geometric model of the furnace is established according to the the actualsize by ratio of1:1. And the sub-regional hybrid grid models is implemented accordingto the structure and flow characteristics in the furnace.2. The simulation model is established coupled with the non-premixed combustionmodel, turbulent flow model of gas, particle orbital model, radiant heat transfer model,pulverized coal volatile combustion model ect. Simultaneously, a one-dimensionaldistributed parameters model of the waterwall is established, from which the waterwalltemperature is obtained and used as the boundary condition for the CFD simulation.3. This paper has satisfied the need of reading data files with waterwall parameterswhich are under the transcritical conditions by using secondary development function ofFluent. After the simulation, distribution characteristics of furnace temperature field, flowfield, as well as the composition concentrations field are obtained under the basicconditions, different load conditions and the transcritical varying load conditions. And asystematic analysis is carried out. This paper laid an important theoretical basis foroptimal operation and improvement of design of the furnance.