Physical And Chemical Properties And Wetting Characteristics Of Entrained-flow Gasification Fine Ash

The gasification fine ash produced in the entrained-flow gasifier has small particle size,complex composition and diverse forms.The low-energy and efficient removal of fine ash is essential to ensure long-term stable operation of the gasification system.The physical and chemical properties of the gasification fine ash of different sources and different particle sizes,the combustible content,surface groups,chemical composition and mineral composition of entrained-flow gasification fine ash are measured and analyzed in the thesis.The wetting characteristics of different gasification fine ash and the influence of the physical and chemical properties of fine ash on its wetting characteristics were investigated.The main conclusions are as follows.There is a good linear relationship between the average pore size,the content of combustibles,the percentage of fine particles of silicon-alumina and particle size distributions.As the particle size increases,the specific surface area of the fine ash increases,the average pore size decreases,the content of combustibles increases,and the percentage of silicon-aluminum fine particles decreases.There is no obvious linear relationship between the absorption peak intensity of the Si-O-Si and-OH groups.For gasification fine ash from different sources with similar particle size distribution,the content of-OH in the fine ash from coal gasification is generally low.The content of combustibles in fine coal ash or raw coal blended with petroleum coke gasification coal ash is higher.The contact angle of opposed multi-burner coal-water slurry gasification fine ash generally decreases as the fine ash particle size increases,but does not change monotonously with the particle size.The increase in the content of surface groups dominated by Si-O-Si and-OH and the content of inorganic minerals dominated by SiO2 in fine ash are beneficial to the enhancement of their wetting characteristics.There is a good linear relationship between the peak area of Si-O-Si groups,the peak area of-OH groups and their contact angles.When the particle size of the gasification fine ash is less than 20μm,the wetting characteristics of the fine ash decreases as the particle size increases.The five main ions of Ca2+,Na+,K+,SO42-and Cl-contained in the liquid have no obvious effect on the suspension and immersion behavior of the gasification fine ash.Ultrasonic excitation helps the vaporized fine ash to be immersed in the liquid.The ultrasonic excitation in the first 5s has the most significant effect on the suspension rate.