水煤浆粒度级配模型和实践的研究进展

Research progress on coal water slurry particle size gradation model and practice

水煤浆是一种煤基液态燃料,具有与燃料油相似的物理特性,是煤炭高效清洁利用的一个重要途径,可显著减少NOx和SO2的排放。目前我国水煤浆需求量已突破2.5亿t/a,粒度级配作为影响水煤浆浓度的重要因素,使不同大小的煤颗粒互相填充,尽可能减少空隙,提高颗粒的堆积效率和水煤浆浓度。分析了粒度级配对水煤浆的影响,指出在水煤浆制浆过程中,粒度级配只涉及物理破碎和研磨,能耗相对较小,显著提升浓度,具有广泛的适用性和经济性。论述了近年来新发展的粒度级配理论和模型,特别是隔层堆积理论和分形级配理论,并给出了具体的计算方法和公式,以及假设和适用性。通过举例给出近年来隔层堆积理论的发展和应用,以及对于堆积效率的具体评价;分析了分形级配理论的可行性和新的研究进展,以及在指导烟煤和褐煤级配时的应用效果;给出了三峰级配的工艺流程、级配方案和工业实践案例。在粒度级配提高水煤浆浓度的基础理论和应用实践方面,国内外学者已做大量工作。但在具体的理论细节方面,如隔层堆积对于任意粒度分布的简化计算、分形级配的拟合精度以及三峰级配的粒度堆积评价还需更深入的研究。在级配理论应用于实践过程中,基础理论和工业实践的结合还有待于进一步提高。在粒度级配基础上,建议引入内在水分等影响因素,建立跨煤种的预测模型。

Coal water slurry(CWS),a coal-based liquid fuel with similar physical properties to oil,is an important way for efficient and clean utilization of coal,which can significantly reduce the emission of NO x and SO 2.At present,China's CWS demand has exceeded 250 million tons/year.Particle size gradation technology is an important factor affecting the concentration of coal water slurry,as different sizes of coal particles can be filled with each other to improve the packing efficiency of particles and the concentration of CWS.This paper analyzes the influence of particle gradation on CWS,and points out that in the CWS making process,the particle gradation only involves physical crushing and grinding,and the energy consumption is relatively small,which has significant effect on improving the concentration and has wide applicability and economy.The theory and model of particle gradation developed in recent years,especially the interlayer packing theory and fractal gradation theory,are discussed,and the specific calculation method,formula,hypothesis and applicability are given.The development and application of the interlayer packing theory in recent years and the evaluation of the packing efficiency are given by examples.The feasibility and new progress of fractal gradation theory and its application in bituminous coal and lignite CWS are analyzed.The technological process and industrial practice cases of three-peak gradation are given.Scholars have done a lot of work on the basic theory and application of particle gradation to improve CWS concentration.However,in following specific theoretical details need to be further studied:the simplified calculation of interlayer packing for arbitrary particle size distribution,the fitting accuracy of fractal gradation and the theory of three-peak gradation.In the application of gradation theory,the combination of basic theory and industrial practice needs to be further improved.It is suggested to introduce the influence of internal water and establish a prediction model for different types of coal in the future research.