| China has large abundant lignite resource. Developing the high-capacity Ultra-supercritical lignite boiler in China is very important to the sustainable development of the electric power industry. Lignite with high moisture, low heat, and low ash melting point, easy to slag on the wall of furnace put forward higher requirements to the organisation of combustion. The project of simulation of aerodynamic in lignite boiler and the combustion prosess is supporter by National High Technology Research and Development of China (863 Programe), and the project will Provide a reference for the development of high-capacity Ultra-supercritical lignite boiler.Simulate the flow field of the 1000MW brown coal boiler modeling test bed on the Computational Fluid Dynamics (CFD) software FLUENT with different computing model and grid and compare with experimental results of the aerodynamic. On this basis, simulate the aerodynamic of the 1000MW lignite bolier. Research shows that the furnace flow field obvious dual tangential, was inclined tangentially oval, ellipse flow is due to the formation of groups in the upstream jet burner jet under the influence of different deflection angle caused by the furnace. Exit gas flow good field symmetry, flue gas velocity showed bilateral high, middle low, the top high, bottom low of features. The furnace exit velocity tends to be uniform with the increase of height; dual tangential in a single boiler tangential exit velocity deviation is less than one tangentially fired boiler furnace; middle section of the furnace for different boundary conditions on the export of flow was less affected.With the FLUENT CFD software, the numbercal simulation of the combustion process in a 600MW lignite boiler has considered the impact of water, and compared to the industrial test results. Simulate the 1000MW brown coal boiler combustion process in this based. Investigate the bias of 1#3#6#8# primary air jet, different station of the secondary air nozzles, the Horizontal Bias Burner and WR burner structure parameters on the furnace flow field, particle trajectories, heat load distribution, the concentration of gas components impact. Research shows that the bias of primary air can not significant effected the overall flow field, but it can lead the separation of the primary air and secondary air, delay the ignition and burnout, strengthen the effect of air classification, reducing NOx emission; large reversed tangential primary air can cause the jet stagnation attached to thermal side of furnace wall in high temperature and high coal concentration and low air velocity, easy to form the phenomenon of coal slag particles. The double waisting secondary air could enhance the strength of air rotating, lower the wall and two inscribed circle in the middle section of the flue gas velocity, improve air staging combustion, reduce the intensity of the primary combustion zone pulverized coal combustion and reduce overall NOx emission. Due to the small momentum of the primary air jet, the combustion of Horizontal Bias Burner and WR burner in the large-scale space of the furnace is simler to eachother, raising the level of shading than Burner help to strengthen the effect of concentrate of pulverized coal to combustion. |
