Coal Diffusion And Combustion Fraction In Circulating Fluidized Bed Furnace

Feed-coal method of large-scale Circulating Fluidized Bed (CFB) boiler directly influences the safe and economical running. During of design the CFB boiler, the distribution of combustion fraction in the furnace directly decides the arrangement of heating surface and the feasibility of CFB boiler performance. Feed-coal diffusion and mixing characteristics in the dense phase region in CFB boiler were researched, to find a best-fit way to combustion and desulphurization. Conversation of energy in subsection of furnace adopted to build the model of combustion fraction, which can exactly predicate the distribution of combustion fraction in the CFB boiler furnace.We carried out the front-wall feed-coal arrangement cold experiment and modeling building research work. Firstly, we finished the cold experiment and feed-coal diffusion in a large-scale two-dimensional CFB boiler; Secondly, according to cold experiments and existing achievements, we have built a one-dimensional theoretic model, and extended it to a two-dimensional theoretic model by using "symmetrical principle", and revised it by using feed-coal macro data of 130 t/h and 440 t/hCFB boiler in the power-plant, then got a practicable model; Finally, we predicated on 670 t/h and 1025 t/hCFB boiler by using the built model, and provide a base for large-scale CFB boiler design and safe running.Meanwhile, according to the conversation of energy, we divided the furnace into several sections along the height of CFB boiler, and built the equations of conversation of energy. Basing on the field data of 440 t/hCFB boiler, in the condition to satisfy the conversation of energy, the combustion fraction model was built. We simulated 670 t/hCFB boiler which designed by Institute of Engineering Thermophysics (EET) by using the model. Comparing the numerical temperature to designed temperature, the results indicated that the finished model can exactly simulate the combustion fraction research results in the CFB boiler design, and provide the theoretic support in the CFB boiler design made by IET.According to the performance test code for utility boiler and CFB boiler, we made a thermo checking program of boiler which can be applied to field data analysis of power-plant units, and validated the program by using the field data of 440 t/h units. This program can be used for engineering projects.