化工学报 ›› 2008, Vol. 59 ›› Issue (9): 2322-2327.

• 能源和环境工程 • 上一篇    下一篇

谷壳热解过程中颗粒孔隙结构分形特性

胡松,向军,孙路石,付鹏,杨涛,苏胜,陈巧巧   

  1. 华中科技大学煤燃烧国家重点实验室
  • 出版日期:2008-09-05 发布日期:2008-09-05

Fractal characteristics of rice husk/char particles prepared by pyrolysis process

HU Song, XIANG Jun, SUN Lushi, FU Peng, YANG Tao, SU Sheng, CHEN Qiaoqiao   

  • Online:2008-09-05 Published:2008-09-05

摘要:

由于颗粒相本身的复杂特性,因此研究者多是对生物质颗粒定性或就某一方面进行描述。借助分形理论可以对颗粒物理结构进行全面而精确的表征。本文利用分形BET方程,基于非线性最小二乘法,提出一种新的分形维数计算途径。该方法是根据多层吸附理论,对氮气等温吸附/脱附法测定的数据分析,直接获得表征整个吸附范围的颗粒分形维数,同时回归得到吸附过程中的吸附层数。分析表明,该方法计算得到的分形维数在数学层面上可以很好地表征颗粒内部微孔特征,同时通过对计算得到的吸附层数分析发现该计算结论也能被多层吸附理论解释,表明该方法在物理层面上也符合实际情况。利用该方法计算得到谷壳在快速热解条件下焦颗粒分形维数的变化。

关键词:

谷壳, 热解, 吸附/脱附, 分形BET, 吸附层数

Abstract:

Due to the complex structure of char particle, most of researchers can only describe particles qualitatively or in a specific aspect.Fractal theory is a powerful tool to describe complex phenomena comprehensively and precisely.In this paper, a new method which is based on fractal BET model with the help of non-linear least square is introduced to calculate fractal dimension.Multilayer adsorption theory was combined with the corrected Kelvin equation to analyze nitrogen adsorption/desorption data to get the fractal dimension which represented whole pore characteristics of the measurement range.Meanwhile, this method regressed the layers during the adsorption process.The analysis result showed that not only calculated fractal dimension could represent particle pore network satisfactorily but also calculated adsorption layers could be explained by the multilayer adsorption theory.This method has both satisfying mathematical result and physical significance.This method was used to calculate the fractal dimension of rice husk char particles prepared by high speed pyrolysis.

Key words:

谷壳, 热解, 吸附/脱附, 分形BET, 吸附层数