Numerical Study Of Pulverized Coal Combustion Process In A1000MW Ultra-supercriticaltower Type Lignite Boiler

With the rapid development of the power industry, China’s energy supply hasfaced the great challenges. China’s exploitation of bituminous coal resources in recentyears has become increasingly depleted. Lignite resources are relatively abundant. Butlignite has the characteristics of high moisture, low heat, low melting point, etc. So fuelconsumption of lignite fired boiler is more than the consumption of the bituminous coalboilers with the same capacity by one time. Its dimensions are also much larger. So itbrings up higher requirements for the design of the lignite boiler. Tower type boiler hasthe characteristics of even gas flow and distribution of temperature. Now thecombustion way of1000MW tower type boiler is always the tangential firing boiler.Tangential firing tower type boiler has high furnace framework, large bulk and heavyweight. So the construction of tangential firing tower type boiler cost more. Dual circletangential firing single chamber tower type boiler can effectively solve these problems.This thesis numerically simulated the aerodynamic and the combustion process inthe1000MW Ultra-supercritical tower type lignite boiler employing the ComputationalFluid Dynamics (CFD) software FLUENT.Firstly this thesis simulated the aerodynamic of the1000MW Ultra-supercriticaltower type lignite boiler. The numerical results showed the flow field distribute law ofthe1000MW Ultra-supercritical tower type lignite boiler and also showed the effect ofdifferent commission mode of pulverizing coal mill on the aerodynamic of the boiler.This thesis also simulated the pulverized coal combustion process in the1000MWUltra-supercritical tower type lignite boiler. The results showed furnace flow field, thetemperature profile, the concentration of gas components and particle trajectories..This thesis simulated the pulverized coal combustion process of single chambertower type boiler, single chamber Π-type boilers and tangential firing tower type boilerfor its full-load conditions. Flow field, the temperature profile, the concentration of gascomponents were compared by same condition, and the inhomogeneities of boiler exitswere evaluated at the same time.Users’ defined function in FLUENT was also adopted to simulate the slaggingprocess in the furnace. The slagging area in the primary combustion zone waspredicted..