Abstract: In the next generation high-temperature solar thermal power system, solid particles are the dominant heat absorbing fluid. Special heat exchangers need to be developed for the energy transmission between particles and other functional thermal fluids, considering the poor fluidity of solid particles. Shallow fluidized bed with immersed pipes is a promising technology for extracting heat from high-temperature particles. However, there is still a lack of unanimous criteria for the optimization design of such devices, especially when non-homogeneous particles with great economic benefits are used. As the first step in the research and design program, the fluidization characteristics of polydisperse bauxite particles in a three dimensional shallow fluidized-bed with built-in tubes were investigated via cold state experiments. Bed pressure drops were measured under five different perforated plate distributor with a range of open area ratio from 0.38% to 2.89%. The effects of open area ratio, static bed height and air distribution mode on the characteristic parameters and quality of the fluidization were also investigated. The results showed that there was no obvious abrupt change in the bed pressure drop curve of the non-homogeneous particles, and the whole process could be divided into three stages: fixed bed, semi-fluidization and complete fluidization. The open area ratio had little influence on the characteristic velocities at the boundary of two adjacent stages. For the concerned non-homogeneous particles, the change of standard deviation of bed pressure drop showed a minimum value, and the fluidization stability became the highest when plate with an opening area ratio of 0.79% was used. The air distribution mode has an important influence on the local bed pressure drop in the multi-chamber fluidized bed. The uniform velocity mode could effectively reduce the pressure drop difference between chambers and improve the uniformity of the overall fluidization zone.

Key words: fluidized-bed with immersed pipes, non-homogeneous particles, open area ratio, pressure drop characteristics, standard deviation

摘要： 针对含内埋管的3维浅层流化床，以空气和非均匀铝矾土铸造砂颗粒为气相和固相开展冷态实验，采用压差变送器测量了5种不同开孔率布风板的床层压降，考察了开孔率、静床高度及流化仓室配风模式对非均匀颗粒流态化特征参数及流化质量的影响。结果表明，非均匀颗粒的床层压降特性曲线不存在明显的突变，流化过程分为固定床、半流态化和完全流态化三个阶段，各阶段分界点特征速度受开孔率影响不大。对于平均粒径为215 μm的非均匀颗粒，床层压降标准差随开孔率的变化存在极小值，开孔率为0.79%的布风板流态化稳定性最高。配风模式对多仓室流化床局部床层压降有重要影响，采用等风速模式可有效降低仓室之间的压降差异，提高整体流化空间的均匀性。

关键词: 埋管流化床, 非均匀颗粒, 开孔率, 压降特性, 标准差