CIESC Journal ›› 2017, Vol. 68 ›› Issue (11): 4105-4111.DOI: 10.11949/j.issn.0438-1157.20170542

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Minimum fluidization velocity of ultrafine particle agglomerates

LIU Daoyin, WANG Yuanbao, WANG Zheng, CHEN Xiaoping   

  1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, Jiangsu, China
  • Received:2017-05-03 Revised:2017-07-26 Online:2017-11-05 Published:2017-11-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51676042).

超细颗粒聚团流化的临界流化速度

刘道银, 王远保, 王铮, 陈晓平   

  1. 东南大学能源热转换及其过程测控教育部重点实验室, 江苏 南京 210096
  • 通讯作者: 刘道银
  • 基金资助:

    国家自然科学基金项目(51676042)。

Abstract:

Minimum fluidization velocity (Umf) of three ultrafine particles (SiO2, Al2O3 and TiO2) was measured in a fluidized bed with inner diameter of 50 mm. The primary particle size (dp) of these ultrafine particles was ranged from 30 nm to 5 μm and Geldart A reference particle was a size of 45 μm. Results show that all three particles have the same Umf change pattern with increase of primary particle size. Umf first increased gradually as dp increased from 30 nm to 5 μm and then Umf decreased sharply as dp increased further to 45 μm. Umf at dp=45 μm was close to that of dp=30 nm and 200 nm. Umf of different materials decreased in the order of TiO2, Al2O3, SiO2. For particles of the same material, dp effect on Umf was similar to that of repose angle, which reached to a maximum at dp=5 μm. Simulation by agglomerate force balance model shows that average size of fluidized agglomerates is changed similarly to that of Umf with regards to different materials and primary particle sizes.

Key words: ultrafine particle, agglomeration, fluidized bed, minimum fluidization velocity, force balance model

摘要:

在内径50 mm的流化床实验台上,测量SiO2、Al2O3和TiO2 3种超细颗粒原生粒径从30 nm增加到5 μm的临界流化速度(Umf),并以Geldart A类颗粒(粒径45 μm)为参照。结果表明:3种超细颗粒的Umf随粒径的变化规律一致,随原生粒径从30 nm增加到5 μm,Umf逐渐增大;当颗粒粒径增加到45 μm,Umf大幅度减小,其与原生粒径为30和200 nm时接近。对于不同材料,Umf由大至小的顺序依次为TiO2、Al2O3、SiO2。粉体安息角测量表明:对于同种材料颗粒,原生粒径对超细颗粒的Umf和安息角的影响规律一致,即5 μm超细颗粒的安息角最大。聚团尺寸模型计算表明:稳定流化时,聚团尺寸随原生粒径的变化趋势以及随不同材料的变化趋势均与Umf的变化趋势一致。研究结果为超细颗粒流化临界速度预测研究奠定了基础。

关键词: 超细颗粒, 团聚, 流化床, 临界流化速度, 力平衡模型

CLC Number: