Experiments On The Fusibility Of Coals Ash Under Pressurized Fluidized Bed Gasification

Coal is the dominant energy in the energy production and consumption structure of our country. With continued growth in energy consumption, environmental issues appear gradually, and the clean use of coal is concerned by increasing people. Coal gasification is the development of clean coal technologies, and pressurized fluidized bed coal gasification with its coal adaptability, and low emissions is to be an important development direction.The fusibility of coal ash is an important characteristic in pulverized coal combustion and coal gasification, which determines how to utilize coal resources in coal combustion or gasification. But there are some operation problems such as bed fusion, bed agglomeration and deposition in fluidized gasification technology, the paper mainly did experimental and theoretical research on coal ash fusibility which is important to solving these problems.Firstly, analyzed the influences of coal ash characteristics and atmosphere on coal ash fusibility, the results shows the fusion temperature is not only concerned with the sum of CaO and Fe₂O₃, but also with the ratio of CaO and Fe₂O₃;Secondly, experiments on the pressure thermal-balance apparatus and XRD, analyzed the influences of pressure and atmosphere on the mineral transformation in the coal. The results shows that the pressure will influence the balance of ash mineral chemical reactions suppress calcite, sulfuric acid Calcium and potassium mica decomposition and promote the transformation of quartz and mullite, calcium and iron spinel. The impact of pressure on the fusibility of coal ashes is complex.Then, analyzed the sintering temperature of coal ashes which is adding additives alter the proportion of alkaline oxides under different atmospheres. The results show the sintering temperature under coal gasification condition is lower than that under oxidizing atmosphere. And with the increase of Fe₂O₃, CaO, Na₂O content, the sintering temperature decreases.At last, we used the calculation software-FACTSage to simulate the influences of pressure and atmosphere on the mineral transformation in the coal ashes. Calculation shows that, with the heating process, the low-temperature minerals gradually transformed into high-temperature minerals; pressure suppress calcium sulfate decomposition and promote the transformation of mullite, anorthite, and cordierite. Reducing atmosphere, mainly through reacting with iron compounds, change the ash mineral components, thereby affecting the fusibility of coal ashes.