木醋液对牛粪堆肥过程传热传质影响的试验研究

发布时间：2018-08-19 06:05

【摘要】：随着新疆规模化畜牧养殖业的快速发展，，畜禽粪便等养殖废弃物已造成新疆环境的严重污染，并逐渐成为畜牧养殖业可持续健康发展的限制性因素。堆肥是实现畜禽粪便减量化、无害化和资源化的的重要途径，而传统堆肥堆料压实度大、通透性差及不均匀性导致堆体空间传热和传质速率变异较大，与堆体传热传质相关的温度、湿度和氧气浓度等状态变量存在较大的空间梯度，在堆体内分布不均，不利于提高堆肥效率和堆肥产品质量，因此迫切需要高效的堆肥制剂来改善堆肥过程堆体热质传递性能。本试验以牛粪为堆肥原料，系统研究木醋液添加对牛粪堆肥过程堆体结构性能、导热性能及温湿度场空间变化及堆体氧气含量扩散等效果的影响，掌握堆肥过程中木醋液添加对堆肥热质传递各状态变量空间变化影响规律，研究成果可为牛粪堆肥过程中热质传递各状态变量的调控、堆肥工艺条件的改进以及堆肥产品的资源化利用提供新的技术途径。主要研究结果如下：（1）通过牛粪好氧堆肥试验研究了添加木醋液对堆肥过程中空间容重变化、堆体导热性能变化、温湿度场变化及氧气等气体扩散的影响。研究发现，与传统堆肥相比，木醋液添加能够降低堆体容重，有利于热量、氧气的扩散及水分的渗透；增大堆体空间热导率，使堆体升温速率加快，有利于加快整个堆肥系统热量的平衡；增大堆体空间氧气扩散能力，有利于提高堆肥产品质量。（2）试验研究了堆肥过程热质传递各状态变量之间的的内在关系，通过曲线拟合发现，堆肥过程堆体空间温差随热导率变化符合三次方程函数关系，堆体热导率对堆体空间温差有显著的影响。热导率增大有利于缩小堆体空间温差；堆肥过程堆体空间湿度随堆体容重变化符合三次方程函数关系，容重对堆体空间湿度动态变化有显著的影响，容重减小，堆体水分渗流作用增强，有利于缩小堆体空间湿度差异；堆体空间氧气含量随堆体容重减小易扩散，有利于促进堆体空间氧气分布均匀性。（3）运用层次分析法评价木醋液添加堆肥各处理热质传递效果，最终得出添加2.9%浓度的木醋液处理热质传递效果最好，其次是1.7%浓度木醋液处理，再次是0.5%浓度木醋液处理，最后是对照处理。
[Abstract]:With the rapid development of large-scale animal husbandry in Xinjiang, livestock and poultry manure has caused serious environmental pollution in Xinjiang, and has gradually become a restrictive factor for the sustainable and healthy development of animal husbandry. Composting is an important way to realize the reduction, harmless and resource utilization of livestock and poultry manure. However, the large compaction, poor permeability and inhomogeneity of the traditional compost lead to great variation of heat transfer and mass transfer rate in the heap space. The temperature, humidity, oxygen concentration and other state variables related to heat and mass transfer of the reactor have large spatial gradient, which is not conducive to improving composting efficiency and composting product quality. Therefore, efficient composting agents are urgently needed to improve the heat and mass transfer performance of composting process. In this experiment, the effects of adding wood vinegar on the structure, thermal conductivity, space variation of temperature and humidity field and diffusion of oxygen content in cow dung compost were studied systematically. In the process of composting, the effects of adding wood vinegar on the spatial variation of state variables of heat and mass transfer of compost were grasped, and the research results could be used to regulate the state variables of heat and mass transfer in the process of composting of cow dung. The improvement of composting process conditions and the utilization of compost products provide a new technical approach. The main results are as follows: (1) the effects of adding wood vinegar on volume density, thermal conductivity, temperature and humidity field and oxygen diffusion during composting were studied by aerobic composting with cow dung. Compared with the traditional compost, the addition of wood vinegar liquid can reduce the bulk density of the reactor, which is beneficial to the heat, oxygen diffusion and water penetration, increase the thermal conductivity of the reactor space and accelerate the heating rate of the reactor. It is helpful to accelerate the heat balance of the whole composting system, to increase the oxygen diffusion capacity of the compost, and to improve the quality of compost products. (2) the internal relationship between the heat and mass transfer variables in the composting process is studied. According to the curve fitting, it is found that the variation of space temperature difference with thermal conductivity in composting process accords with the function of cubic equation, and the thermal conductivity of reactor has a significant effect on the space temperature difference of reactor. The increase of thermal conductivity is beneficial to the reduction of the space temperature difference, and the change of bulk humidity with bulk density in composting process accords with the cubic equation function, and the bulk density has a significant effect on the dynamic change of bulk humidity and decreases in bulk density. The effect of water seepage on the reactor is enhanced, which is helpful to reduce the difference of space humidity, and the oxygen content in the reactor is easy to diffuse with the decrease of bulk density. It is helpful to promote the uniformity of oxygen distribution in the reactor space. (3) the heat and mass transfer effect of wood vinegar added with compost is evaluated by analytic hierarchy process. Finally, the heat and mass transfer effect of wood vinegar solution with 2.9% concentration is the best. The second was 1.7% wood vinegar treatment, the second was 0.5% wood vinegar treatment, and the last was the control treatment.
【学位授予单位】：塔里木大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S141.4

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