Numerical Simulation Of Pulverized Coal Combustion Process In A 1000MW Dual Circle Tangetial Firing Single Chamber Boiler

With the increasing requirement for electric power and the attention of environmental protection,USC power generation,for its characteristics of high-duty, high-efficiency,low-energy consumption,excellent environmental protection and relatively matured technology, is the only way for China's clean coal technologies. With the development of super-high-duty boiler, single chamber dual circle tangential firing technology was developed,and has been widely used at abroad,and was also applied on the first USC boiler in China.But it was rarely reasearched at home.This thesis numerically simulated pulverized coal combustion process in the first 1000 MW dual circle tangential firing single chamber USC boiler in China, employing the Computational Fluid Dynamics (CFD) code PHOENICS.The numerical results showed the temperature profile and flow field distribute law of dual circle tangential firing single chamber boiler,and also showed the effect of different commission mode of pulverizing coal mill on temperature profile,heat duty, concentration distributions of the combustion species in furnace and overal NOx emission level of the boiler.In addition, three different cases with 80%, 60% and 40% boiler full load were simulated,to evaluate the sustained combustion characteristic of part load operation.In the numerical calculation of furnace process, the turbulence is accounted for by conventional k-εtwo equations model. The two fluid model based on Inter-phase Slip Algorithm is employed for the two-phase flow simulation. Radiation uses the Six-Flux model. Particle drying is modeled by diffusion model. The devolatilization process is modeled by one step reaction model. Turbulent combustion of volatiles is modeled by EBU-Arrhenius model. Char combustion is modeled by diffusion-kinetics model. In the numerical simulation of NO emission, a post-processing run is employed for the NO simulation based on the results of the main combustion process in the furnace. Thermal NO is predicted using the extended Zeldovich mechanism. The Fuel NO calculation is performed using equations for HCN and NO transport with the reaction mechanisms proposed by De'Soete. The deoxidization effect of char to NO is considered and prompt NO is overlooked. The governing equations are discretized over a non-uniform staggered grid in the Cartesian coordinate using the finite difference method and the equations are solved by SIMPLEST algorithm.This thesis shows that numerical simulation of furnace process in pulverized coal fired boiler with proper mathematical models and calculation method is viable. The numerical simulation of temperature field and the concentration distributions of the combustion species in the furnace are reasonable and they can reveal the actual flow, heat transfer, combustion process and NO emission in boiler furnaces.This above results of this thesis have significant practical importance to absorb the super high duty generate electricity technology introduced from abroad, and also to the reaearch and development of our own. This subject is part of China's National High Tech. R&D Program"USC power generation technologies"and research results have been accepted by experts.