摘要
采用5光纤速度探头对f100mm?5.1m循环床提升管8个高度截面上11个径向位置的局部颗粒速度进行了实验测试,并采用径向不均匀指数(RNI)对颗粒速度径向分布的不均匀性及其沿轴向的变化进行了定量描述。研究结果表明:在高气速、高颗粒循环量操作时,操作条件对颗粒上升速度和下降速度的径向分布的影响在加速段和充分发展段呈现出不同的规律;颗粒上升速度和下降速度沿轴向的变化在核心区和边壁区也表现出不同的趋势。当颗粒循环速率大于200 kgm-2s-1时,颗粒的加速段长度大大延长,以至于大于提升管的高度(15.1m)。颗粒速度径向分布的不均匀性沿轴向是逐渐增大的,并且与截面平均颗粒速度存在很强的相关性。
To investigate the influence of operating conditions on particle movement and the radial distribution and axial development of particle velocity, local vertical ascending and descending particle velocities in a CFB riser of 15.1m high and 0.1m i.d. were systematically measured by an improved five-fiber optic particle velocity probe, with superficial gas velocity ranging from 3.5 to 8.2 ms-1 and solids circulation rate from 53 to 202kgm-2s-1. The experimental data obtained at 11 radial positions on 8 axial levels delineated clearly the radial distribution and the axial development of particle velocities in CFB risers. Results show that under higher superficial gas velocity and/or solids circulation rate, the effects of operating conditions on ascending and descending particle velocities in acceleration section are quite different from those in fully developed section, and the axial development of local particle velocities in core region are also different from that near the bed wall. Further, a radial non-uniformity index (RNI), proposed by Zhu and Manyele, is applied to describe quantitatively the non-uniformity in radial distribution of time mean particle velocities, which indicates that the radial non-uniformities of particle velocities increase up the riser, and correlate strongly with cross-sectional average particle velocities.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2002年第2期168-173,共6页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金--海外青年基金资助项目(29928005)。
关键词
循环流化床
颗粒速度
径向不均匀指
气固两相流
circulating fluidized beds
local particle velocity
radial non-uniformity index
