Combustion characteristics of rice husk powder with different size

doi:10.16085/j.issn.1000-6613.2017-1290

Abstract

Abstract: To explore the combustion characteristics of rice husk powder,the effect of different sizes on the minimum ignition temperature (MIT)of the rice husk powder was measured based on the experimental dust layer and dust cloud,the lower explosive limits (LEL),heat release properties and dynamic characteristics were tested by the Hartmann tube,cone calorimeter,and thermogravimetry/differential scanning calorimetry (TG/DSC),respectively. The results showed that the MIT and LEL declined with the decreasing size of the chaff powder,while the maximum explosion pressure and the rate of explosive pressure increase rose. The explosion pressure reached 0.9MPa for the sample with the size of 80~96μm,the MITs of dust layer (5mm and 10mm)and dust cloud were 130℃ and 430℃,respectively. The combustion characteristic index S_N was 3.82×10^-7,increased by 57.2% comparing to the sample with the size of 180~1250μm. The maximum release heat peak was arisen at 307s,and its intensity increased to 62kJ/m². The reaction activation energy of corresponding pyrolysis process increased from 35.35kJ/mol (sample of 180~1250μm)to 51.15kJ/mol,which demonstrated that the combustion process transformed diffusion-controlled into kinetically controlled reaction with the decreasing particle size.

Key words: reaction kinetics, powders, safety, pyrolysis, biofuel

摘要： 为了探索谷壳糠粉的燃烧特性，基于粉尘层和粉尘云实验研究了粒径对其最低着火温度的影响，采用哈特曼管和锥形量热仪测试了不同粒径谷壳糠粉的爆炸下限和热释放性能，利用热重/差式扫描量热仪系统地研究其燃烧特性和燃烧动力学。结果表明：随着谷壳糠粉粒径的减小，其最低着火温度（MIT）和爆炸下限浓度（LEL）降低，但最大爆炸压力P和爆炸压力上升速率均增大。其中粒径为80～96μm样品的爆炸压力为0.9MPa，其粉尘层（5mm及10mm）和粉尘云最低着火温度分别为130℃和430℃，燃烧特性指数S_N达到3.82×10^-7，较粒径为180～1250μm样品提高了57.2%；在307s出现最大释热峰，且最大释热峰值强度增加至62kJ/m²，对应热解过程的反应活化能由35.35kJ/mol（180～1250μm样品）增大至51.15kJ/mol，表明其燃烧过程随粒径的减小由扩散控制转变为动力学控制过程。

关键词: 反应动力学, 粉体, 安全, 热解, 生物燃料

CLC Number:

WANG Yachao, ZHAO Jiangping, WANG Yujiao, LI Hua, CUI Xiaohong, LIU Penggang, FU Linzhi. Combustion characteristics of rice husk powder with different size[J]. Chemical Industry and Engineering Progress, 2018, 37(05): 1774-1780.

王亚超, 赵江平, 王玉娇, 李华, 崔晓红, 刘鹏刚, 付林志. 不同粒度谷壳糠粉的燃烧特性[J]. 化工进展, 2018, 37(05): 1774-1780.

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