Circulating Fluidized Bed Boiler Combustion Characteristics Of Coal Relationship

With the rapid development of the national economy, the demand for electricity is rising increasingly, and the number of power plant's coal-fired boiler is also gradual increasing, but at present, the supply of China's power plants's coal-fired has a obvious problems, the contradiction between demand and supply has become prominent, there is a big differences between burning coal and design of the actual coal in many power plants, especially in the circulating fluidized bed boiler which have the features of fuel to adapt to broad, ofen burn the coal-fired that have a larger deviations than the designed fuels. Thus, to China's power plants using many kinds of coal, the large changes in coal quality, and understand the relationship between the combustion characteristics of CFB boiler and the coal changes is very necessary to the boilers'safety and economic operation.By now, the researches to the circulating fluidized bed combustor in the areas of the complex flow, combustion, chemical reactions and heat transfer during many scholars at home and abroad, generally use more targeted experimental studies, but the method of using computer models to study the complex phenomenons such as the combustion is relatively small, especially with the FLUENT software, the simulation to large-scale fluidized bed combustion boiler is more small. Given the current status of research, this thesis studies the research on the first domestically 300MW units' circulating fluidized bed boiler in Yunnan Province's the first phase of the project of Honghe power plant,, using FLUENT software, and aiming at the simulation study of the relationship between the fluidized bed boiler and the coal combustion characteristics.This thesis first describes the current status of China's energy development and the coal combustion mechanism in the circulating fluidized bed, and then build the combustion model:the gas flow choses turbulence model; gas-solid flow selected the stochastic particle trajectory model of the method based on Lagrangian; volatile coal combustion model takes the two-step reaction model of competition, and the coke combustion with power/ diffusion-controlled reaction rate model, the gas's burning choses a single mixture fraction method; the radiation heat transfer model uses the P-1 model, in order to establish combustional model of the circulating fluidized bed. Then, using FLUENT software, with the application of SIMPLE algorithm, carried out the numerical simulation to the 300MW units'CFB boiler of buring Xiaolongtan lignites; Finally, the temperature field, components, etc.are given the corresponding analysis, and supplemented by the actual engineering data of the boiler operation to verify the simulation results, proving the credibility of the simulation results. The thesis also carried out the numerical simulation to switch to the anthracite in the boiler, and the simulation results show that the boiler is more suitable for burning lignite of Xiaolongtan.