| With the rapid growth of China's national economy and the improvement of people's living standards,China's demand for electricity has increased dramatically,and the phenomenon of “electricity shortage” has occurred.And thermal power is still China's current main mode of power generation,with the continuous expanding of the installed capacity,the demand for coal in power plant is also growing and large-scale power plants are in a perennial situation of coal supply shortage.In the face of the huge demand for electricity and the tight supply of coal,it is difficult for the power plant to burn the designed coal for a long time,but to burn two or even kinds of coal.Beacause of the large difference in the coal quality characteristics,it may cause combustion instability,slag increasing,more pollutant emissions and other issues.Therefore,the power plants usually design a reasonable blending program to protect the boiler safety,stability and economic operation.In this paper,the 350 MW supercritical boiler is used as the research object.The designed coal of the boiler is lignite,but the lignite has low calorific value,high volatilization and insufficient combustion.In order to solve the problem of severe coking and low thermal efficiency,field test study for low-quality bituminous coal was operated.Considering the characteristics of low ash content and high calorific value of bituminous coal and the actual situation of the power plant,it selected Hesi Wula lignite,Shaltala lignite and Shanxi Ge Pu bituminous coal to conduct this study.First,the HS-TGA-101 thermogravimetric analysis of ten kinds of blended coal with different proportions was carried out by using thermogravimetric analysis.And the variation rule of ignition temperature of mixed coal with different mixing ratio was summarized.By analyzing the properties of blended coal that consist of two kinds and three kinds of coal,the change of ignition characteristics and combustion parameters were obtained when the lignite was mixed with bituminous coal.The results showed that the flammability index C of the mixed coal decreased with the increase of the proportion of Shanxi Ge Pu bituminous coal,while increased with the increase of the proportion of the saladilla,and the stability of coal quality is improved,which provides a theoretical basis for the design of concrete blending.Secondly,use the SDTGA2000 automatic industrial analyzer to do industrial analysis experiments on a variety of blended coal to get real-time industrial analysis data as the foundation of next step calculation of the best ratio.Then,take the coal price and the sulfur content of blended coal as the objective function of the multi-objective fuzzy decision-making model and the industrial analysis data as the constraint condition,calculate and obtain the optimal blending ratio which is proved satisfied for the economic and environmental protection,providing theoretical basis for field test research next step.Finally,conduct a 30-day field test on a thermal power plant boiler to analyze if burning check coal Hesi Wula lignite only and burning 9 different kinds of blended coal with various proportions of bituminous coal can ensure the safe operation of power plant boilers.Through the analysis of the influence of temperature parameter change(analysis of water temperature,superheater and reheater temperature,main steam temperature,etc.)and coking conditions,it analyzed the safety of the process of blended-coal combustion in this paper. |
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