Research On Numerical Simulation Of The Combustion Process Of A600MW Supercritical W-shape Flame Boiler

In modern times，with the rapid development of the technology of computerhardware and software,the numerical simulation technology based on ComputationalFluid Dynamics(CFD)develops quickly.Due to being proved truly by the high precisenumerical forecasts of flow,heat transfer,combustion and chemical reaction in manyengineering practice of numerical simulation on the combustion process of boiler,thenumerical simulation increasingly becomes popularized and adopted inmany otherengineer fields.This paper adopted the boiler which was designed and manufactured by HarbinBoiler company limited in accordance with the technology of Mitsui Babcock,and it’s thefirst banch of supercritical W-flame boilers using such technology.During commissioningand commercial operation,the over-temperature of waterwall condition which greatlyaffects the safe and stable operation of the boiler occurs frequently. In order to find thereasons of overtemperature on the combustion side of the water wall and put forwardrecommendations of combustion adjustment,it was necessary to conduct a numericalsimulation of the combustion process for the furnace and analyze the situation ofcombustion. The realizable k-two equations turbulent model was used to simulate theturbulence.The stochastic tracking model was applied to analyze the gas-solid flow field.The P-1model was applied to simulate radiation.Two competing reaction model andProbability Density Function were corresponding the devolatilization process and thecombustion of volatile. Diffusion-kinetics model was used to simulate char combustion.Before performing simulation,this paper conducted a statistical analysis of theover-temperature data of water wall,and initially identified the central waterwall of frontwall to be easy to overtemperature. These data could provide some support for fielddata.Then aiming at a600MW supercritical W flame boiler of a power plant inYunnan,used CFD simulation software FLUENT6.3to perform dimensional steady flowfield numerical simulation within the furnace.Whereafter this paper analysized the resultsunder hot state at different conditions of temperature,velocity,the oxygen concentrationfield.Summarized as follows:This paper respectively simulated three conditions about thesecondary air under the arch accounting for20%,15%,10%of the total secondary airwhen the air volume of the front and back arch was equal.These three conditions derivedtemperature,velocity,and oxygen concentration fields have suffered different degrees ofskew,so called " the front wall push the back wall "phenomenon.Among these three conditions,the general of degrees of flame fullness and skew was best when thesecondary air under the arch accounting for15%of total secondary air.So it can be usedas the basic condition.The paper also respectively simulated increasing the proportion of secondary air onthe front arch by5%and10%.The result showed that the condition of increasing5%wasbetter according to combustion situation.And finally simulated the conditions that reduced the output of the medium coalmill of front wall.When the medium area of the upper front water wall occuredovertemperature,we can take such measures.Especially serious overtemperaturecondition,we can consider to cut the coal mill corresponding to the area ofovertemperature.