不同畜禽粪便的热解特性及反应动力学

Characteristics and kinetics of pyrolysis for animal manures

对猪、牛和鸡3种主要种类畜禽粪便在以高纯氮气为载气的条件下进行热重-差热(TG-DSC)分析,同时考察不同升温速率(10、20和50℃/min)对鸡粪样品热解过程热解特性和热焓的影响。热重试验样品粒度为0.5mm,所有样品均从室温加热至1 000℃。试验结果表明:畜禽粪便类生物质热解过程主要包括脱水、主要热裂解和炭化3个阶段,3种畜禽粪便样品失重主要集中在126～438℃;不同种类畜禽粪便样品和不同升温速率,鸡粪样品的DTG、DSC曲线差异明显,但各自的DTG和DSC曲线有很好的对应关系;基于Coats-Redfern法应用反应级数模型和扩散模型选择回归系数最高的值表示样品的反应级数和反应机理,得出鸡粪活化能的平均值为73.4kJ/mol,猪粪、牛粪活化能分别为114.2和88.5kJ/mol。

Pyrolytic characteristics of three kinds of manures（swine,cattle and chicken） were investigated,respectively,under highly pure N2 circumstance using a thermogravimetric analyzer（TGA） with differential scanning calorimetry（DSC） detector.At the same time,different heating rates（10,20 and 50 ℃/min） were used for chicken manure to investigate the influence of heating rate on pyrolytic characteristics.The particle size of samples was 0.5 mm and the temperature range was from room temperature to 1 000 ℃.The results indicate that the pyrolytic process of manures mainly includes three stages：water losing stage,main weight loss stage（126-438 ℃） and carbonization stage.There are obvious discrepancies on DTG and DSC curves of different samples with different heating rates of chicken manure.However,it seems that the DSC curve of each sample is corresponded well with its DTG curve.Based on Coats-Redfern method,the kinetic parameters were obtained by the reaction order model and diffusion model.The largest regression coefficient represented the sample’s reaction order and mechanism.The calculated values of activation energy for chicken manure,cattle manure and swine manure are 73.4（average value）,88.5 and 114.2 kJ/mol,respectively.