Study On Mineral Distribution In Coal Blends And Its Influence On Ash Melting Behavior

China is rich in coal but lack of oil and gas,while the power industry is a large user of coal.Power plant boilers generally use low-quality,inferior and non-design coal.After many times of transportation and blending,the coal is more complicated.In the process of pulverized coal combustion,slagging and the water wall blasting accident in the furnace occur frequently.Therefore,in-depth study of the slagging mechanism of coal-fired boilers,improve the prediction accuracy of coal-fired slagging tendency,and timely rational adjustment and prevention can significantly improve the economic and safety of coal-fired boilers.In order to explore the distribution of minerals in blended coal and its influence on the fusibility.In this paper,two typical Jincheng coal and Zhundong coal with a great difference were chosen as raw materials.The raw coal sample is crushed to less than 3mm,and is ground to ?150 ?m in accordance with Zhundong: Jincheng at a ratio of 100:0,70:30,50:50,30:70,0:100(mass ratio).According to GB/T478-2008,the pulverized coal samples were subjected to full density floatation separation and similar density level combination with the float-sink test.The coals were then combusted in the muffle furnace and the high temperature furnace.The chemical composition and mineral composition of coal ash were studied by XRF and XRD.The fusibility of coal ash was studied by pyramidal method.The species,morphology and particle size of minerals in coal were determined by optical microscope and electron microscope.The particle size distribution of the pulverized coal sample and the coal ash sample was analyzed by a laser particle size analyzer.The study found that the grinding process has a certain impact on the density composition of coal.The coal with higher hardness is more easily separated from organic coal and inorganic minerals.Among them,Jincheng coal is concentrated in lowdensity components.The chemical composition of each density of Zhundong coal and Jincheng coal is quite different.The influence of density grading on the east coal is mainly concentrated in the ZD1 component.The most important component of the Jincheng coal sample is JC4.The ash chemical composition of each sample of different density grades of blended coal B5050 is significantly reduced compared with the ash chemical composition of different density grades of single coal.However,there are still uneven melting phenomena in blended coal.With the increase of proportion of Jincheng coal,the melting temperature of coal ash increases gradually.In the research,a method for predicting the slagging property of boiler based on uneven melting of coal ash was found.The slagging property of pulverized coal combustion was predicted according to the melting temperature and percentage of low-melting coal ash.According to the analysis of the particle size distribution by the laser particle size analyzer,the coarse ash particles and the fine ash particles have different slagging tendency.There are 35 figures,10 tables and 84 references in the thesis.