玉米秸及玉米芯的燃烧动力学参数分段研究

Study on Combustion Kinetic Parameters of Corn Straw and Corncob at Different Stages

生物质能源因其储量大、可再生、CO2净排放为零等特点,可以作为化石等传统能源的替代能源为人类提供能源。为了能够充分利用生物质能,对其燃烧过程中的动力学参数进行研究具有重要意义。本研究利用TG-DTG技术对玉米秸及玉米芯进行热重实验,选用五个机理函数,按照挥发分析出、挥发分燃烧和焦炭燃烧三个主要阶段分别对玉米秸和玉米芯的燃烧过程进行动力学参数计算。研究结果表明,玉米秸与玉米芯燃烧规律大致相同,可以分为三个主要阶段,两者的质量快速减少区间都在250℃至500℃区间。玉米秸燃烧第一个阶段使用机理函数F2二级化学反应得到的模型精度最高,剩余两阶段宜使用机理函数F1一级化学反应,活化能最高为第一阶段19.56 kJ/mol。而对于玉米芯来说第一个阶段及第三个阶段宜使用F3三级化学反应机理函数,第二个阶段宜使用D1一维扩散机理函数,活化能最高在第三阶段为114.80kJ/mol。玉米芯燃烧过程比玉米秸更加复杂,燃烧过程涉及基本化学反应机理和扩散机理,且活化能较高。

Biomass energy can provide energy for human as alternative to fossil energy with features of large reserves,renewability and zero net CO2 emission.To make full use of biomass energy,it is of great significance to study kinetic parameters during combustion process.The study conducts thermogravimetry experiments on corn straw and corncob with TG-DTG technology.Choosing five mechanism functions,calculate kinetic parameters corn straw and corncob in combustion process according to three main stages of volatilization analysis,volatilization combustion and coke combustion.Results show combustion rules of corn straw and corn cob are basically the same,which can be divided into three main stages,rapid mass reduction range of both is from 250℃to 500℃.At first stage of corn straw combustion,second-order chemical reaction of mechanism function F2 can achieve the most accurate model.At remaining two stages,first-order chemical reaction of mechanism function F1 can achieve the highest activation energy of 19.56 kJ/mol.For corncob,at first stage and third stage,with F3 three-stage chemical reaction mechanism function,with D1 one-dimensional diffusion mechanism function at second stage,the highest activation energy is 114.80 kJ/mol at the third stage.Combustion process of corn cob is more complicated than corn straw,which involves basic chemical reaction mechanism and diffusion mechanism,with higher activation energy.