不同粒径棉花秆粉末压制成型颗粒燃烧动力学特性

为掌握不同粒径棉花秆粉末压制的成型颗粒燃烧的动力学特性,开展不同粒径粉末的热重分析,并将粉末压制为质量相当的成型颗粒,开展成型颗粒燃烧失重实验,并采用等温热分析的双对数方法进行动力学分析。结果表明:棉花秆粉末粒径较大时,灰分也较高,在较低温度下燃烧可形成骨架,有利于挥发分和氧气的扩散,促进燃烧速率。压制成型颗粒时,棉花秆粉末粒径越小,粉末间结合越紧密,压制的成型颗粒密度越大,相同条件下的燃烧失重速率明显降低,表现活化能从77.71 kJ/mol逐渐降至69.44 kJ/mol。成型颗粒的高温燃烧过程可分为2个阶段,首先是水分和挥发分全部析出,而后为焦炭燃烧阶段。燃烧温度可显著加快水分和挥发分的析出速度。

RESEARCH ON COMBUSTION KINETIC CHARACTERISTICS OF MOLDED PARTICLES COMPRESSED BY COTTON STALKS POWDER WITH DIFFERENT SIZE

In order to understand the combustion kinetic characteristics of the molded particles compressed by different cotton stalk powder size,the thermos-gravimetric analysis of powder with different size is carried out firstly,and then the powder with different sizes is compressed into particles with same weight.After that,the weight loss experiments during the molded particle combustion are conducted.At last,the kinetic analysis is carried out by using the double logarithmic method of isothermal analysis.The results indicate that more ash is found in the big size powder.The ash may build the skeleton under lower temperature combustion,which strengthens the diffusion of volatiles and oxygen so that the combustion velocity is accelerated.During the process of compressing particles,the smaller the powder size of raw cotton stalks,the tighter powder united.The mass loss rate of combustion under the same condition is reduced significantly.The apparent activation energy is reduced form 77.71 kJ/mol to 69.44 kJ/mol.The process of particle combustion may be divided into two stages.In first stage,all of the water and volatiles are volatilized,In second stage,the residual char burned.The combustion temperature significantly increases the precipitation rate of water and volatile components.