液固流化床内颗粒沉降特性试验研究

Study on settlement characteristic of the grain in fluidized bed

以小于1.5cm的粗煤泥颗粒为研究对象,根据密度级和粒度级的不同,将粗煤泥分成20种窄密度级和窄粒度级的均质颗粒,在100mm液固流化床粗煤泥分选机内,分别进行自由沉降试验和干扰沉降试验,干扰沉降包括干扰沉降速度的试验和悬浮体密度的测量。结果表明,分选机内的流态应属于过渡区域,阿连公式是粗煤泥颗粒自由沉降末速的合适公式;影响干扰沉降速度的主导因素是介质中固体颗粒数量的多少和粒群的结构特点,固体容积浓度λ越大,颗粒的干扰沉降速度降低系数β越小;机体内从底部到顶部,流化床中悬浮体的密度逐渐减小,但在接近悬浮体顶部,悬浮体的密度稍有增加;随着密度和粒度的增加,悬浮体密度自下而上减小的程度增大。

Took thick goal grains（less than 1.5 cm） as research object,according to different densities and particle sizes,thick goal grains were divided into 20 kinds of narrow density and narrow size level average grains.Free settling and hindered settling tests were respectively carried out in 100 mm fluidized bed thick goal separators.Hindered settlement includes hindered settling velocity test and measurements of suspension density.The results show that fluid state in separator belongs to transition region.Alien＇s law is the appropriate formula of thick coal particles free settlement terminal velocity.The main factors affecting hindered settling velocity are the number of solid particles in medium and the structure feature of the particle group.The bigger volume fractions of solids λ is,the smaller decreasing velocity coefficient of particle hindered settlement β becomes.In the organism from bottom to top,density of suspended particles in fluidized bed gradually decreases,but near the top of the suspended particles,the density increases slightly.With the increase of density and size,suspension density reducing extent increases from bottom to top of separators.