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快速流化床径向空隙率分布的数学模型研究
张文楠
Subtype硕士
Thesis Advisor董元吉
1988-06-30
Degree Grantor中国科学院研究生院
Abstract本工作采用光导纤维空隙率测量仪对快速流化床内径向空隙率分布规律进行了系统研究,建立和完善了光纤传感器等面积插值回归的标定方法,使其测量精确度大幅度提高。实验在内径90mm,高10m的有机玻璃循环床中进行。利用已有的多点压差自动扫描系统建立了一套直接从计算机标定和测量床层两点间压差的程序,解决了肉眼难以读数的困难。通过对大量实验数据处理,得到了描述径向空隙率分布规律的关联式,并利用固体浓度分布重心的概念定量分析和径向空隙率分布特征。以实验数据为基础,考虑到模型建立和求解的可能性,本工作开发了快速流态化床内径向驱动—扩散模型,该模型不仅适用于快速床,也适用于湍流和鼓泡床,与目前所能获得的径向孔隙率分布的实验数据均能吻合。与此同时,为求解模型方程组,采用了多维优化求解方法。模型计算表明,径向分布形式取决于床层中颗粒聚团的大小随颗粒浓度变化的规律;径向孔隙率分布不均匀的主要原因是气速径向分布的存在,这种不均匀性反过来又会影响径向气速分布;同时表明,径向孔隙率分布的存在将削弱快速率浓相区内固体的整体滑移,澄清了径向分布不均匀与快速床形成的关系。
Other AbstractPorous pellets have been obtained in this thesis by burning away the combustible material (saw wood-dust) which has previously been mixed in the pellets so as to leave pores behind. Sequence programing temperature change is taken into account in the reduction process. Rate constant is obtained from the heating-up exp. in which temperature changes from 700 TO 1000'C. By comparing, the result is proved reliable. As concerns heating-up speed, the activity energy are nearly the same when heating-up speed do not change greatly, that is that hematite pellet reduction is not affected obviously by heating-up speed. By means of examining the partially reduced samples both macroscopically and microscopically, measuring energy spectrum, the manner by which the reduction of hematite pellet has been determined. Finely, the unreacted-core shrinking model is applied in iso-thermal reduction process. The computed results are in good agreement with the results observed by experiments. And the applicability of non-isothemal mathematical model to hematite-pellets has been discussed. It is appropriate in the conditions of constant activity energy and mono-interface reduction.
Pages83
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8411
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
张文楠. 快速流化床径向空隙率分布的数学模型研究[D]. 中国科学院研究生院,1988.
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