Distribution And Heat Volatilization Of Fusible Elements In Zhundong And Jincheng Pulverized Coal And Their Influence On Ash Fusibility

Xinjiang and Shanxi are both large provinces of coal resources in China.However,in the process of utilization of coal resources,furnace slagging and slag hanging on the furnace wall occur,which can’t keep the effective gasification of coal,and eventually cause forced boiler shutdown,resulting in low operation rate of gasifier.By analyzing the distribution and thermal volatilization of the fusible elements in the pulverized coal of Zhundong,Xinjiang and Jincheng,Shanxi,this study explains the distribution of the fusible elements and the influence of the thermal volatilization on the fusibility of the coal ash,in order to prevent the slagging of the ash fusion fluidized bed gasifier,improve the reaction temperature of the gasifier,and provide some theoretical guidance for the design and operation of the coal gasification system.In this paper,Shanxi Jincheng Anthracite and Xinjiang Zhundong long flame coal are selected as the research objects.In order to get close to the actual industrial production conditions,the raw coal is first finely ground to a certain particle size to meet the experimental requirements,and the full density floating sedimentation method is used to float the coal powder,and the density grade is combined according to the production rate and ash content.The distribution of sulfur,iron,potassium and sodium in the form of pulverized coal and coal ash were measured.According to the changes of chemical composition and mineral composition of samples with different densities after ashing at different temperatures,the law of thermal volatilization of fusible elements is summarized.The ash melting point of each density class sample after ashing at different temperatures was measured to explore the distribution of fusible elements and the effect of thermal volatilization on the fusibility of coal ash.It is found that the fusible elements are distributed unevenly in the coal powder and coal ash of Jincheng and Zhundong.The sulfur in Jincheng coal is mainly pyrite sulfur,which is concentrated in JC4（>2.0g/cm³）,and the content of pyrite iron is the highest.In Zhundong coal,organic sulfur is the main form of low density,pyrite sulfur is the main form of high density,and the total iron content is relatively low.No matter Jincheng coal or Zhundong coal,the main form of sodium is water-soluble sodium,and the main form of potassium is acid soluble potassium.The mineral composition of Jincheng coal ash and Zhundong coal ash is quite different,and the law of mineral volatilization is also different.In Jincheng coal ash,SiO₂ and Al₂O₃ are the main components,Fe₂O₃ is positively related to temperature,SO₃ is negatively related to temperature.At 1300 ℃,SO₃ is basically volatilized completely,and alkali metals K and Na are concentrated in the low density level,which decreases with the increase of temperature.The content of Fe₂O₃ in Zhundong coal ash is lower,which is positively related to temperature.SO₃ decreases with the increase of temperature.The content of K and Na is higher than that in Jincheng coal ash,which is negatively related to temperature.Aft data show that the ash melting temperature of Jincheng coal decreases obviously at JC4,which is the result of pyrite accumulation in JC4.The characteristic temperature of ZD at 815 ℃ was significantly increased by the volatilization of fusible elements.The melting temperature of Zhundong coal ash fluctuates between 1100 ℃ and 1300 ℃,and 1200 ℃ is an important temperature node of Zhundong coal.