不同植物纤维的热解和燃烧特性研究

Study on pyrolysis and combustion characteristics of different plant fibers

本研究采用不等温热重法研究六种纤维(针叶、阔叶、竹、亚麻、草和棉)在N_(2)和空气气氛下的热解和燃烧特性,并采用Friedman法对其进行动力学分析。结果表明,纤维不同的热解和燃烧特性参数与其自身结构组成有关。纤维在热解和燃烧过程中,其挥发分析出温度Ts、终止温度T_(h)、DTG峰温T_(max)、固定碳燃烧峰温、最大质量损失速率、热解指数P和燃烧指数S均随着升温速率的增加而增加;在N_(2)气氛下,亚麻纤维T_(max)最大,竹纤维T_(max)最小,棉纤维的Ts最大,草纤维的最大热解质量损失速率−(dm/dt)_(max)、热解指数P和燃烧指数S均最小;在转化率为0.05−0.85条件下,阔叶纤维平均表观活化能最小(173.3 kJ/mol),竹纤的最大(201.10 kJ/mol)。在空气气氛下,所有纤维的热解过程的T_(max)均低于N_(2)条件下,在转化率为0.05−0.65时,纤维在空气中热解的表观活化能E_(α)低于其在N_(2)条件下的表观活化能。

In order to study the pyrolysis and combustion characteristics of different fibers,the kinetics of six kinds of plant fibers(coniferous,broadleaf,bamboo,flax,grass and cotton)in N_(2) and air atmosphere were studied by non-isothermal thermogravimetric(TG)method using Friedman method.T_(h)e results showed that the fibers had different pyrolysis and combustion characteristic parameters,which were related to their own structural compositions.In the process of pyrolysis and combustion of fibers,the initial volatilization temperature(Ts),terminal decomposition temperature(T_(h)),DTG peak temperature(T_(max)),fixed carbon combustion peak temperature,maximum mass loss rate,pyrolysis character index(P)and combustion character index(S)increased with the increase of heating rates;In N_(2) atmosphere,the flax fiber T_(max) and bamboo fiber T_(max) were shown to be the highest and lowest among all fibers,respectively,and Ts of cotton fiber was the largest;Grass fiber had the smallest maximum pyrolysis mass loss rate(−(dm/dt)max),pyrolysis index(P),and combustion index(S);Between the conversion of 0.05−0.85,the average apparent activation energies(E)of broadleaf fiber and bamboo fiber were the smallest(173.30 kJ/mol)and highest(201.10 kJ/mol),respectively.In air atmosphere,T_(max) of all fibers in the pyrolysis process was lower than that in N_(2).T_(h)e apparent activation energy(Eα)of fiber pyrolysis in air atmosphere was shown to be lower than that in N_(2) when the conversion was between 5%and 65%.