添加生物质助燃物改善牛粪燃烧性能

    Improvement for combustion performance of cattle manures by adding biomass combustion-supporting materials

    • 摘要: 为了改善牛粪的燃烧性能,该研究以栾树干、稻草和玉米芯为助燃物,采用热重分析法计算分析了纯牛粪及其与各助燃物在1∶1、2∶1和3∶1 3种质量配比下的混合燃烧性能与燃烧反应动力学行为。结果表明:添加助燃物后的牛粪混料着火特性较纯牛粪变化不大,但燃尽特性有较为明显的改善,其中稻草和玉米芯的改善效果要优于栾树干,且稻草略好于玉米芯;栾树干、稻草和玉米芯3种混料在不同质量配比下的综合燃烧特性指数的平均值分别为1.89×10-10、2.09×10-10和2.45×10-10 mg2/(K3·min2),相对于纯牛粪分别提高了9.88%、21.51%和42.44%;在活化能E和频率因子A构成的燃烧反应活性分布图上,以纯牛粪为参考点,3种质量配比下的玉米芯混料均向高反应活性区大幅移动,而稻草混料需要在较大的配比下才能大幅向高反应活性区移动,栾树干混料则均一定程度地向低反应活性区移动。以上研究结果为基于农林废弃物的牛粪混合燃烧处理提供了依据和参考。

       

      Abstract: Abstract: With the increasing cattle feeding operations, cattle manure disposal is becoming a problem due to its increasing production and potential contamination of soil, air, ground and surface water sources by running off from the manure sites and odor releases. It is greatly urgent to explore high efficiency and sustainable disposal solutions for the cattle manure. Combustion disposal represents a promising alternative due to the advantages of high temperature elimination of pathogens, drastically reducing waste stream volume, as well as extracting useful heat. However, cattle manure consists of a great quantity of ash, which is harmful to the combustion efficiency and performance of cattle manures and gives a challenge for the design of a high efficiency burner. Under this context, it is necessary and important to improve the combustion performance of cattle manures. Therefore, in this research, some agricultural and forest residues, such as koelreuteria elegans, straw, and corn cob, were considered as combustion-supporting materials in order to improve the combustion performance of cattle manures. The combustion characteristics and kinetics of the mixtures between cattle manures and the agricultural and forest residues with different mass ratios (such as 1:1, 2:1, and 3:1) were conducted in detail on the basis of thermogravimetric analysis. The combustion characteristics were evaluated by considering ignition and burnout temperatures, burnout characteristic index, as well as comprehensive combustion characteristic index. The kinetic parameters of activation energy (E) and frequency factor (A) were obtained based on the Arrehenius equation. It was found that the ignition performance of the cattle manure only has a little change after adding those combustion-supporting materials under the different mass ratios. However, the burnout performance after adding those materials has an obvious improvement, in particular for straw and corn cob. The averages of comprehensive combustion characteristic indices for the koelreuteria elegans, straw, and corn cob under the three different mass ratios are 1.89×10-10, 2.09×10-10, and 2.45×10-10 mg2/(K3·min2), respectively. They are considerably larger than that of the cattle manure with an increase of 9.88%, 21.51%, and 42.44%, respectively. On the activity distribution plane of combustion reaction developed by the activation energy and frequency factor, the reaction activities of the cattle manure mixtures by mixing the corn cob under the three different mass ratios all have an outstanding movement toward the high activity region relative to that of the cattle manure, while for an obvious movement toward the high activity region for the mixtures of the straw, it is needed to add the straw with a large mass ratio (e.g., 1:1). Moreover, the reaction activities of the mixtures by adding the koelreuteria elegans under the three different mass ratios almost all have a movement toward the low activity region. Experiment results demonstrate that the corn cob is a good choice as a combustion-supporting material for the improvement of the combustion performance of cattle manures. This research provides a useful reference for the improvement of the combustion performance of cattle manures and lays a solid foundation for the disposal of cattle manures in the perspective of combustion.

       

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