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.