【作者】 王琳；

【导师】 赵广播；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2010， 硕士

【摘要】 随着全球对NOx排放量的要求越来越严格,低NOx燃烧器在电站锅炉中得到越来越广泛的应用。但在一些采用低NOx旋流燃烧器的燃煤电站锅炉中出现炉内结渣严重、低负荷稳燃能力差和煤种适应性差等问题。因此深入研究旋流煤粉燃烧器的气固两相流动特性是十分必要的。本文对日本石川岛播磨公司开发的双旋流燃烧器进行了三维PDA试验,研究了不同二次风风量和不同内外二次风叶片角度下燃烧器的气固两相流动特性。双旋流煤粉燃烧器在二次风风量为0.099kg/s的工况下不存在回流区,在二次风风量为0.142kg/s和0.184kg/s的工况下存在较小的环形回流区。三种二次风风量下,在二次风流动区域和边壁区域存在两个颗粒体积流量峰值和相对颗粒数密度峰值,在燃烧器中心线附近的粒径始终低于径向其它位置的粒径。在三种外二次风叶片角度下,双旋流煤粉燃烧器具有较小的环形回流区,在x/d=0.1-1.0的截面,颗粒体积流量呈双峰分布,颗粒体积流量峰值分别位于二次风流动区域和边壁区域,颗粒相对数密度与颗粒体积流量的分布规律基本相同,同时燃烧器中心区域的粒径较小。在两种内二次风叶片角度下双旋流煤粉燃烧器都存在着壁面回流,在燃烧器出口附近出现了较小尺寸的环形回流区。在x/d=0.1-0.7的截面,颗粒体积流量呈双峰分布,颗粒相对数密度的分布与颗粒体积流量分布规律相似。在x/d=0.1-0.5之间的截面,中心线附近的粒径始终低于径向其它位置的粒径。在不同二次风风量和不同内、外二次风叶片角度下,双旋流煤粉燃烧器的气固两相轴向、径向和RMS切向脉动速度的分布规律基本相同,与轴向速度和径向速度相比,切向速度衰减的较快,而且切向脉动速度也比较小。更多还原

【Abstract】 With the increasing stricter requirement of NOx emission all over the world, swirl burners with low NOx formation are more and more widely used in thermal power plants in China. However, a series of problems were arisen on the boilers adoping swirl burners, such as serious slagging in furnace, poor combustion stability at low load, and low adaptability of coal fineness. Thus, it is necessary to conduct study on gas-particle flows characteristics of low NOx swirl burners. In view of this, experiments were performed on Double-swirl Flow burner designed by Ishikawajima-Harima Heavy Industries Co., Ltd in Japanese. A three-dimensional PDA system was used to study gas-particle flow characteristics of DF burner with different secondary air fluxes and vane angles of inner and outer secondary air.When the mass flux of secondary air was 0.099kg/s, the recirculation zone could not form. There was a small ring recirculation zone with the mass flux of 0.142kg/s and 0.184kg/s. For three different mass fluxes of secondary air, two peak values of particle volume flux and relative number density of particles appeared in the secondary air flow zone and near-wall region. The diameter of particles near the chamber axis of burner was always less than that at other positions.The DF burner had a small ring recirculation zone near the burner nozzle with three different outer secondary air vane angles. The profiles of the particle volume flux had two peaks at sections of x/d=0.1-1.0, one was in the secondary air region and another was in the near-wall region. The relative number density of particles profiled similar to the particle volume flux, and the particles in the central region of burner were small.With two different inner secondary air vane angles, back flow occur in the near-wall region, and there was small ring recirculation zone near the burner nozzle. At sections of x/d=0.1-0.7, the particle volume flux had two peaks values while the relative number density had similar profiles. At sections of x/d=0.1-0.5, the diameter of particles near the chamber axis of burner was always less than that at other positions.The DF burner had similar distributions of axial RMS velocities, tangential RMS velocities and radial RMS velocities with different secondary air mass flux, inner and outer secondary air vane angles. Compared with the axial and radial velocities, the tangential velocities attenuated more quickly, and the tangential fluctuation velocities were lower.更多还原