液-固下行循环流化床中的颗粒碰撞行为  

Study on particle collision behavior in a liquid-solid down-flow circulating fluidized bed

作　　者：姜峰[1,3] 刘艺 齐国鹏 李修伦[1] JIANG Feng;LIU Yi;QI Guopeng;LI Xiulun(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China;School of Biological and Environment Engineering,Tianjin Vocational Institute,Tianjin 300410,China;Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology,Tianjin 300350,China)

机构地区：[1]天津大学化工学院,天津300072 [2]天津职业大学生物与环境工程学院,天津300410 [3]天津市化工安全与装备技术重点实验室,天津300350

出　　处：《化学工业与工程》2022年第3期49-59,共11页Chemical Industry and Engineering

基　　金：化学工程国家重点实验室开放项目(SKL-CHE-18B03);天津市科技支撑计划重点项目(2009ZCKFGX01900)。

摘　　要：设计并构建了一套冷模液-固下行循环流化床蒸发器,考察了颗粒对壁面的碰撞行为随轴向位置和操作参数的变化规律,以便更好地揭示循环流化床强化传热和防、除垢的机理。实验中,选用水和不同粒径的聚甲醛颗粒和玻璃珠作为工质,对不同颗粒加入量(0~2.0%)和循环流量(2.15~5.16 m^(3)·h^(-1))下的碰撞加速度信号进行了功率谱密度、峰度和标准偏差等频域和时域分析。研究结果表明:液相和固相碰撞加速度信号的频率范围分别为0~2000 Hz和6000~16000 Hz。沿着下行床的轴向位置从上到下,颗粒对壁面碰撞加速度信号的标准偏差先减小,后增大;峰度增大。随着颗粒加入量和循环流量的增加,标准偏差增大,峰度减小。颗粒加入量较低时,标准偏差随着聚甲醛颗粒粒径的增加先减小、后增大;而峰度随着粒径的增加明显增大。颗粒加入量较高时,标准偏差和峰度随着粒径的增加而增大,但增大的幅度较小。玻璃珠的标准偏差较小,但峰度明显高于聚甲醛颗粒。构建了操作参数对颗粒碰撞行为影响的三维图。研究结果有助于促进流化床换热防垢节能技术的工业化应用。A cold-model liquid-solid down-flow circulating fluidized bed evaporator is designed and built. The effect of the axial position and operating parameters on the particle-to-wall collision behavior is investigated to reveal the heat transfer enhancement and fouling prevention mechanism. Water and different sizes of polyformaldehyde particles and glass beads are selected as the working media in the experiments. The collision acceleration signals are dealt with the frequency and time domains analyses such as the power spectral density, kurtosis and standard deviation under different operating parameters including the amount of added particles(0—2.0%) and circulation flow rate(2.15—5.16 m^(3)·h^(-1)). The results show that the frequency range of the collision acceleration signals are from 0 to 2 000 Hz and 6 000 to 16 000 Hz for the liquid and solid phases, respectively. The standard deviation of the particle-to-wall collision acceleration signals initially decreases and then increases along the axial direction of the down-flow bed from the top to the bottom;however, the kurtosis increases. The standard deviation increases, but the kurtosis decreases with the increases of the amount of added particles and circulation flow rate. The standard deviation of the polyformaldehyde particles initially decreases and then increases with the increase of particle size at low amount of added particles;however, the kurtosis obviously increases. The standard deviation and kurtosis of the polyformaldehyde particles increase with the increase of particle size at high amount of added particles, but the amplitude of the increase in kurtosis is small. The standard deviation of the glass bead is small, but the kurtosis is obviously higher than that of the polyformaldehyde particles. The three-dimensional diagrams are established to reflect the effect of the operating parameters on the particle collision behavior. The findings are beneficial to promoting the industrial application of the fluidized bed heat transfer and fouling preven

关 键 词：颗粒碰撞行为 液-固循环流化床 下行床 功率谱密度 标准偏差 峰度 

分 类 号：TQ021.1[化学工程]