循环流化床颗粒团多参数的光散射测量方法

Light scattering measurement method for multi-parameters of particle clusters in circulating fluidized bed

针对循环流化床床内颗粒团动态参数和行为特性的测量问题,提出了基于光散射原理的颗粒团运动速度、高度与浓度等多参数同时在线测量方法,利用该方法对二维冷态循环流化床试验台开展颗粒团参数测量,获得了颗粒经测量区造成的光强衰减信号,通过对上下测量单元光强信号进行互相关分析可获得颗粒团运动速度参数;对信号进行低通滤波,根据低频信号极值点时间差及运动速度测量结果,得到颗粒团高度参数;同时根据光强衰减程度计算颗粒团的浓度参数。由此实现了基于光散射原理的循环流化床床内颗粒团运动速度、高度与浓度多参数同时在线测量,测量结果显示,在典型工况下,提升管中心区域颗粒团运动速度较为稳定,平均速度为3.81 m/s,近壁面区域颗粒团运动速度有较大波动且出现负值,平均速度为0.65 m/s;中心区域颗粒浓度较近壁面区域小;中心区域颗粒团高度主要分布在20~40 mm区间,近壁面区域颗粒团高度主要分布在30~60 mm区间。这为循环流化床内颗粒团的形成、结构及其运动研究提供了一种有效的测量手段。

Aiming at the measurement issue of dynamic parameters and behavior characteristics of particle clusters in circulating fluidized bed(CFB),a multi-parameter simultaneous on-line measurement method of velocity,height and concentration of particle clusters based on light scattering principle is proposed.This method is used to measure the parameters of particle clusters in a two-dimensional cold test bench of CFB.The light attenuation signal caused by particle clusters flowing through the measurement zone is obtained.The velocity of particle clusters is obtained from the cross-correlation analysis of the light intensity signals of the upper and lower measurement units.The signal is filtered with low-pass filter,and the height of particle clusters is obtained according to the time difference of the extreme points of the low-frequency signal and the measurement results of motion velocity.At the same time,the concentration is calculated according to the light intensity attenuation.Thus,the multi-parameter on-line measurement of velocity,height and concentration of particle clusters in CFB is realized based on light scattering.The measurement results show that under typical working condition,the velocity of particle clusters in the central zone of riser is quite stable,and the average velocity is 3.81 m/s.The motion velocity of particle clusters in the near wall zone has large fluctuations,even is negative,and the average velocity is 0.65 m/s.The concentration of particle clusters in the central zone is less than that in the near wall zone.The height of particle clusters in the central zone is mainly distributed in the range of 20~40 mm,and the height of particle clusters in the near wall zone is mainly distributed in the range of 30~60 mm.The results provide an effective measurement method for studying the formation,structure and motion of particle clusters in CFB.