Influence of Pulverized Coal on Characteristics of Fly Ash in SCGP

Abstract

The chemical composition, microstructure and size distribution of pulverized coal and fly ash samples from SCGP(Shell Coal Gasification Process) devices of four different regions were measured using an energy dispersive spectrometer, a scanning electron microscope, and Coulter particle analyzer. The paper aims to analyze the influence of pulverized coal on characteristics of fly ash. The energy dispersive analysis showed the main elements of chemical composition of fly ash and pulverized coal were C, O, Si, Al, and small amounts of metal elements. The difference of chemical composition of pulverized coal samples illustrates the types of coal were different. The similarity in chemical composition of four types of fly ash was due to the same technical process. Scanning electron microscope measurements showed particulate microstructures of four samples of pulverized coal were irregular, however, particulate microstructures of samples of fly ash were all spherical. The surface of most spherical particles had microspheres that were often agglomerated together. This phenomenon indicated that particulate microstructures of pulverized coal had no influence on particulate microstructures of fly ash. The size distribution showed median size of four pulverized coal samples were 31.59μm, 28.85μm, 25.57μm and 20.62μm. Median size of four fly ash samples were 4.07μm, 3.89μm, 3.45μm and 3.04μm. The particle size of fly ash increases with the growth of particle size of pulverized coal. The crests of particle size distribution curves of pulverized coal were not obvious due to the grinding evenness of coal were low. Particle size distribution curves of fly ash were opposite. This phenomenon indicates that uniform degree of fly ash is not affected by coal grinding evenness. In conclusion, the particle size of pulverized coal is the main influencing factor on the characteristics of fly ash while the influences of type of coal, particulate microstructures and grinding evenness of pulverized coal are not so much. Particle size of fly ash has a vital influence on high-temperature ceramic filters in SCGP. Controlling particle size of pulverized coal has a certain guiding significance to reducing the working load and extending the life of filter elements.