玉米秸秆成型颗粒高温热解和燃烧特性研究

Study on High-Temperature Pyrolysis and Combustion Characteristics of Corn Straw Briquettes

为分析玉米秸秆成型颗粒燃烧过程中挥发分析出阶段的作用及反应温度对成型颗粒燃烧特性的影响,本文针对成型颗粒设计了等温反应试验系统,在700»1000℃范围内开展成型颗粒高温热解和燃烧实验,分析不同条件下的失重速率与挥发分析出完成时间.结果表明:成型颗粒的高温热解和燃烧均可分为两个阶段,热解过程第一阶段的挥发分析出致使成型颗粒失重达到70%左右,剩余焦炭在第二阶段继续加热过程中失重量很小;燃烧过程第一阶段除挥发分析出外,表层焦炭也在燃烧,且产生的高温可加速成型颗粒内部挥发分的析出,第二阶段为焦炭燃烧.从700℃升高至1000℃时,高温热解和燃烧的第一阶段时间分别缩短了47.6%和44.4%,而燃烧过程中焦炭的燃烧速率提高了约3倍.

To analyse the role of volatile devolatilization process in the briquettes overall combustion process was studied by contrasting the difference in high-temperature pyrolysis process and combustion process at different temperatures,the isothermal reacting experimental system was built.The high-temperature pyrolysis and combus-tion experiments were carried out in the range of 700»1000℃to study the weight loss velocity and devolatilization process time.The results indicated that whether high-temperature pyrolysis or the combustion process of corn straw briquettes could be divided into two stages.The first stage in high-temperature pyrolysis mainly was de-volatilization process,and the weight loss reached 70%in whole briquettes.In contrast,the char was heated in the second stage,and the weight loss was very small.Aimed to combustion process,except for volatile devolatilization,a certain amount of char at the outside surface of briquette was also burned during the first stage.In addition,the outside surface char combustion provided heat to enhance the temperature inner of briquettes increasing,and accelerated the devolatilization process.As the reacting temperature increased from 700℃to 1000℃,the react-ing times of the first stage in high-temperature pyrolysis and combustion process shortened about 47.6%and 44.4%,the combustion velocity of briquettes char combustion process was increased by about 3 times.