光纤法测量气-固两相流中的固含率
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摘要
基于光线照射到颗粒上会发生漫反射这一现象,制作了一种测量气-固两相流中固含率的单光纤探针。对于自由堆积的催化剂颗粒,信号强度随催化剂与探针末端距离的减少而增加。对于其他物体,信号强度随物体与光纤距离的减少先增加后降低,在约1 mm处有极大值。采用板状单摆考察光纤探针对运动物体响应的灵敏性和准确性,实验结果与计算结果一致。分别用压差法和光纤法测量流化床中的固含率并进行比较,固含率较高时,压差法与光纤法的固含率基本相当;受颗粒间遮挡的影响,当固含率较低时,光纤法测得的固含率偏高。提供了一种一定范围内气-固两相流固含率的在线测量方法及原理,丰富了多相流测量理论和实践体系。
A single optical fiber probe, which is used to measure solid holdup in a gas-solid two-phase flow, was developed based on the phenomenon of light diffusive reflection on solid particles. For stacked catalyst particles, the signal intensity increases with the decrease of distance from probe tip to catalyst. For other objects, however, the signal intensity usually increases when the probe is close to the objects and reaches maximum when the above distance is about 1 mm; then the intensity declines as the distance from the probe to the objects goes down. With using a plate pendulum, sensitivity and accuracy of the optical fiber probe for moving objects were investigated, and it was found that experimental results are consistent with theoretical calculation. In addition, the solid holdup in a gas-solid two-phase fluidized bed was measured, and the results from the pressure difference method and the optical fiber method were compared with each other. The above results suggest that the solid holdup obtained from the two methods agree well with each other when solid holdup is high. However, when solid holdup is low, values obtained from optical probe are slightly higher than those from pressure difference method. This work proposes a new method and principle for on-line measurement of solid holdup for a certain concentration range in gas-solid flow, and thus enriches the theory and application of multiphase flow measurement.
A single optical fiber probe, which is used to measure solid holdup in a gas-solid two-phase flow, was developed based on the phenomenon of light diffusive reflection on solid particles. For stacked catalyst particles, the signal intensity increases with the decrease of distance from probe tip to catalyst. For other objects, however, the signal intensity usually increases when the probe is close to the objects and reaches maximum when the above distance is about 1 mm; then the intensity declines as the distance from the probe to the objects goes down. With using a plate pendulum, sensitivity and accuracy of the optical fiber probe for moving objects were investigated, and it was found that experimental results are consistent with theoretical calculation. In addition, the solid holdup in a gas-solid two-phase fluidized bed was measured, and the results from the pressure difference method and the optical fiber method were compared with each other. The above results suggest that the solid holdup obtained from the two methods agree well with each other when solid holdup is high. However, when solid holdup is low, values obtained from optical probe are slightly higher than those from pressure difference method. This work proposes a new method and principle for on-line measurement of solid holdup for a certain concentration range in gas-solid flow, and thus enriches the theory and application of multiphase flow measurement.
引文
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[8]鄂承林,卢春喜,高金森,等.气固两相流中颗粒时均速度的测量新方法[J].过程工程学报,2003,3(6):505-511.(E Chenglin,LU Chunxi,GAO Jinsen,et al.A new method for the measurement of solids time-average velocity in gas-solid two-phase flow[J].The Chinese Journal of Process Engineering,2003,3(6):505-511.)
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[11]WANG C X,ZHU J,BARGHI S,et al.Axial and radial development of solids holdup in a high flux/density gas-solids circulating fluidized bed[J].Chemical Engineering Science,2014,108:233-243.
[12]WANG C X,LI C Y,ZHU J.Axial solids flow structure in a high density gas-solids circulating fluidized bed downer[J].Powder Technology,2015,272:153-164.
[13]金涌,祝京旭,汪展文,等.流态化工程原理[M].北京:清华大学出版社,2001:448.
[14]何广湘,郭晓燕,杨索和,等.气流鼓泡床反应器中气泡行为光纤探针测量方法[J].北京航空航天大学学报,2017,43(2):253-259.(HE Guangxiang,GUOXiaoyan,YANG Suohe,et al.Measurement of bubble behavior by optical probe in gas-liquid bubble column reactor[J].Journal of Beijing University of Aeronautics and Astronautics,2017,43(2):253-259.)
[15]于凤军.单摆系统的振动研究[J].大学物理,2009,28(9):9-12.(YU Fengjun.Study of oscillation of single pendulum system[J].College Physics,2009,28(9):9-12.)
[16]CUI H,MOSTOUFI N,CHAOUKI J.Gas and solid between dynamic bubble and emulsion in gas-fluidized beds[J].Powder Technology,2001,120(1/2):12-20.
[17]TOOMEY R D,JOHNSTONE H F.Gas fluidization of solid particles[J].Chem Eng Process,1952,48(1):220-226.
[2]李晨,范怡平,贾海兵,等.提升管反应器中颗粒浓度径向分布的力学特性[J].过程工程学报,2016,16(4):541-548.(LI Chen,FAN Yiping,JIA Haibing,et al.Mechanical radial distribution of particles concentration in a riser reactor[J].The Chinese Journal of Process Engineering,2016,16(4):541-548.)
[3]张明辉,钱震,余皓,等.大型循环流化床流动结构分析[J].化工学报,2003,54(2):182-187.(ZHANGMinghui,QIAN Zhen,YU Hao,et al.Analysis of flow structure in large-scale circulating fluidized beds[J].Journal of Chemical Industry and Engineering(China),2003,54(2):182-187.)
[4]严超宇,卢春喜.气固环流燃烧器内颗粒流动行为[J].化工学报,2010,61(6):1357-1366.(YAN Chaoyu,LU Chunxi.Fluidization behavior in gas-solid airlift loop combustor[J].CIESC Journal,2010,61(6):1357-1366.)
[5]ABDELSALAM E,MUTHANNA H A.Local timeaveraged gas holdup in fluidized bed reactor using gamma ray computed tomography technique(CT)[J].Int J Ind Chem,2015,6:143-152.
[6]王芬芬,鄂承林,赵爱红,等.提升管中颗粒局部流率和速度的改进的光纤测量方法[J].化工学报,2016,67(8):3209-3223.(WANG Fenfen,E Chenglin,ZHAO Aihong,et al.Method of optical fiber measurement for local particle flux and velocity in riser[J].CIESC Journal,2016,67(8):3209-3223.)
[7]李晓光,徐德龙,范海宏.利用光反射探测流化床中颗粒的动力学行为[J].西安建筑科技大学学报(自然科学版),2006,38(2):154-158.(LI Xiaoguang,XUDelong,FAN Haihong.Exploration of particles dynamic behavior in fluidized bed by means of light reflection[J].Xi’an Univ of Arch&Tech(Natural Science Edition),2006,38(2):154-158.)
[8]鄂承林,卢春喜,高金森,等.气固两相流中颗粒时均速度的测量新方法[J].过程工程学报,2003,3(6):505-511.(E Chenglin,LU Chunxi,GAO Jinsen,et al.A new method for the measurement of solids time-average velocity in gas-solid two-phase flow[J].The Chinese Journal of Process Engineering,2003,3(6):505-511.)
[9]KAPANY N S.Fiber Optics[J].Scientific American,1960,203(5):72-80.
[10]郭慕孙,李洪钟.流态化手册[M].北京:化学工业出版社,2007:862.
[11]WANG C X,ZHU J,BARGHI S,et al.Axial and radial development of solids holdup in a high flux/density gas-solids circulating fluidized bed[J].Chemical Engineering Science,2014,108:233-243.
[12]WANG C X,LI C Y,ZHU J.Axial solids flow structure in a high density gas-solids circulating fluidized bed downer[J].Powder Technology,2015,272:153-164.
[13]金涌,祝京旭,汪展文,等.流态化工程原理[M].北京:清华大学出版社,2001:448.
[14]何广湘,郭晓燕,杨索和,等.气流鼓泡床反应器中气泡行为光纤探针测量方法[J].北京航空航天大学学报,2017,43(2):253-259.(HE Guangxiang,GUOXiaoyan,YANG Suohe,et al.Measurement of bubble behavior by optical probe in gas-liquid bubble column reactor[J].Journal of Beijing University of Aeronautics and Astronautics,2017,43(2):253-259.)
[15]于凤军.单摆系统的振动研究[J].大学物理,2009,28(9):9-12.(YU Fengjun.Study of oscillation of single pendulum system[J].College Physics,2009,28(9):9-12.)
[16]CUI H,MOSTOUFI N,CHAOUKI J.Gas and solid between dynamic bubble and emulsion in gas-fluidized beds[J].Powder Technology,2001,120(1/2):12-20.
[17]TOOMEY R D,JOHNSTONE H F.Gas fluidization of solid particles[J].Chem Eng Process,1952,48(1):220-226.