【作者】 李波；

【导师】 黄镇宇； 程军；

【作者基本信息】 浙江大学 ， 工程热物理， 2010， 硕士

【摘要】 水煤浆气化技术是洁净煤技术的研究热点,在中国引进的最早,且已经得到了较为深入的开发与研究。但是我国的水煤浆气化技术还存在着许多问题,尤其气化喷嘴技术仍然是水煤浆气化技术发展的瓶颈。三通道外混式喷嘴是水煤浆气化炉中应用最为广泛的喷嘴,对三通道外混式喷嘴在加压环境下雾化性能的研究,具有重要的现实意义。本文主要研究了三通道外混式喷嘴在雾化室加压条件下的雾化过程,主要包括实验与数值模拟两个方面：实验方面：首先,在加压环境下对三通道外混式喷嘴的流量特性进行了实验研究与分析；其次,以雾化粒径SMD为研究目标,研究了在加压环境下喷嘴出口结构参数对雾化性能的影响；然后,同样以雾化粒径SMD为研究目标,研究了不同环境压力下负荷、气耗率、气量比等操作工况对喷嘴雾化性能的影响变化,分析了这些变化的原因,并对不同环境压力下不同气耗率时的雾化式样进行了拍照观察,研究了雾化角度的变化特点；最后对工质粘度在不同环境压力下对喷嘴’雾化性能表现的影响作了研究与分析。数值模拟：本文在冷态实验的基础上进行了数值模拟。建立了新型三通道外混式喷嘴的三维物理模型,采用k-ε双方程模型模拟了雾化介质的流场分布,分析了速度场、压力场及回流区的特点。除此以外,还采用大涡模拟和DPM模型对喷嘴出口射流破碎及雾化情况进行了冷态模拟,分析了非稳态雾化场的特点,计算结果对喷嘴的工程设计具有重大指导意义。更多还原

【Abstract】 CWS gasification technology is one of the hot spot of Clean Coal Use(CCU) technologies. Compared with other CCU tecnologies, it is brought into China much earlier and has got much more progress.But there’re many problems still existed, of which CWS nozzle technology is the bottleback of CWS gasification technology development. Three-channel external mixing type nozzle is the most widely used in today’s China. It’s meaningful to study the atomization performance of the three-channel external mixing type nozzle under high ambient pressure. This paper is based on the research work and mainly contains two sections:1.Experiment. First, the paper studies the flow characteristics of the three-channel external mixing type nozzle under high ambient pressure. Second, taking droplet size SMD as the estimate target, the paper studies the effects of both the structure and sizes of the nozzle towards the atomization performance. Also taking droplet size SMD as the estimate target, the paper studies the effect of operation parameters in different ambient pressures and analyzes the reason. Then, the paper analyzes photos of the spray and measures the spray angles under different ambient pressures and air/liquid ratios. Finally, the effects of the liquid viscosity under different ambient pressures towards the atomization performance is discussed.2.Numerical Simulation. Based on the cold-state experiment, numerical simulation is introduced. First, the paper set up 3-D physical model of the three-channel external mixing type nozzle and then analyzes the characteristics of velocity field, pressure field and the reflux area by simulating the distribution of flow field with k-s two-way model.Second, the paper analyzes the atomization field outside the tip of the nozzle with LES and DPM model under unsteady environment. The result is of practical significance for the design of nozzle.更多还原