农业生物质燃烧特性及燃烧动力学

    Combustion characteristics and combustionkinetics of agriculture biomass

    • 摘要: 为了充分燃烧利用农业生物质,采用TG-DTG-DSC(thermogravimetric-differential thermogravimetric-differential scanning calorimetry)联用技术对玉米杆、玉米芯、稻草、龙眼枝、荔枝条及其混合燃料进行了热重试验,考察了其可燃特性、着火特性、燃尽特性及综合燃烧特性,计算了燃烧动力学参数。结果表明,玉米杆及玉米芯燃烧前期DTG曲线分别出现2、3个峰值,而稻草、龙眼枝及荔枝条燃烧前期DTG曲线均只出现一个峰值;玉米杆及稻草燃烧中后期出现DSC曲线的吸热峰;玉米杆的可燃特性指数及着火特性指数均最大,且着火温度最低,荔枝条的燃尽特性指数最大,玉米芯的综合燃烧特性最好;低温阶段反应级数约为1.0~1.2,高温阶段反应级数约为0.5~0.8,低温阶段活化能大于高温阶段的活化能;生物质燃烧前期属于均相着火,后期属于多相着火。秸秆类生物质纯烧的后期稳定性较差,在木质类生物质中适当加入秸秆类生物质有利于混合燃料的前期燃烧,研究结果可为农业生物质的燃烧利用提供指导。

       

      Abstract: Abstract: In order to efficiently utilize agricultural biomass, thermogravimetry experimentation analysis of corn stalks, corn cobs, straw, lychee bar, and longan sticks and its mixed fuel was performed by using the TG-DTG-DSC (Thermogravimetric-Differential Thermogravimetric-Differential Scanning Calorimetry) thermal analysis technology. The combustible characteristics, ignition characteristics, burnout characteristics and synthetic combustion characteristics were investigated, and the combustion kinetics parameters were identified. The results show that the early burning DTG curves of corn stalks and corn cob have two peaks and three peaks, respectively, and the burning DTG curves of straw, longan sticks, and lychee strip each have only one peak. The mixed fuels prophase similar combustion characteristics of corn stalks, straw, and lychee bar show that the three fuels are suitable co-combustion. DSC curves of corn stalks S1 and straw S3 both have one endothermic peak late in the combustion, and the post-combustion needs to absorb more heat in order to maintain its combustion, which indicates that herbaceous biomass post-combustion stability is poor and not suitable for separate combustion. The DSC curve characteristics of wood-based biomass show that wood-based biomass has higher post-combustion stability. The combustible characteristics index and ignition characteristics index of corn stalks are both the largest, and their ignition temperature is the lowest, resulting in excellent pre-combustion performance. The burnout characteristic index of lychee bar is the largest and its burnout rate is the best, but its early combustion characteristics are not easy to catch fire and burn. The synthetic combustion characteristics of corncob are the best. The low-temperature phase of the reaction order is about 1.0-1.2, the high temperature phase of the reaction order is approximately 0.5-0.8, and the corresponding reaction activation energy is larger at the low temperature phase than that at the high temperature phase. The early biomass burning is a homogeneous fire and the late biomass burning belongs to a multiphase fire. The late stability of pure burning straw biomass is bad, but adding straw biomass with wood biomass is conducive to its pre-combustion of mixed fuels. The study results can provide guidance for the combustion and utilization of agricultural biomass.

       

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