| Regarding problems of high carbon content in fly ash and furnace slag, low boiler thermal efficiency which exists in one unit of DG1900/25.4-Ⅱ1 boiler of Qin Bei Power Plant, in this article, through overall test and analysis, the major root cause of low economic performance of the boiler was located , and the economic performance of the boiler was apparently improved through a series of hot state combustion adjustments.The main harmful factors which resulted in low economic performance of the boiler were found through boiler efficiency test and analysis, those factors are as follows: coal characteristic varied frequently; pulverized coal fineness was too large; oxygen content was too low; speed difference of primary air was big; tertiary air distribution of swirl burner was unreasonable and so on. Through a series of purposefulness tests, carbon content in fly ash was adjusted from 20% to 7%, carbon content in furnace slag was adjusted from 8% to 1.5%, CO content in boiler flue gas was reduced from 3288 ppm to 7 ppm, solid unburned loss and gas unburned loss were obviously reduced, boiler thermal efficiency was evidently increased.Pulverized coal fineness is the primary factors of boiler thermal efficiency through in-depth analysis, and adjustment to dynamic and static separator is the main measure of pulverized coal fineness adjustment, therefore, numerical simulation and analysis of the gas-solid two phase flow in dynamic and static separator were developed in this paper by using commercial calculation fluid mechanics software of Fluent. In calculation, the standard k ?εturbulent model and SIMPLE model for gas phase and the Discrete Phase Model(DPM)for particle motion are used to describe the two phase flow. The gas flow and typical diametral particle track were gained, from the simulation results we can know that the pulverized coal fineness became smaller as the accretion of angular velocity of separator moving blades. The simulation and experimental result were in agreement.
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