摘要
为了研究鸡粪的中低温干燥特性,利用恒温鼓风干燥箱,以干燥温度、粪层厚度、风速为因素研究了鸡粪含水率和干燥速率随时间变化的规律,用常见的薄层干燥模型对鸡粪的干燥曲线进行了拟合分析,并用正交试验优化了鸡粪干燥工艺参数。结果表明:鸡粪的中低温干燥过程由2个降速阶段组成,第2降速阶段的干燥速率相对于第1降速阶段下降更快。干燥温度越高,粪层厚度越小,风速越大,干燥速率曲线出现拐点的时间越早,达到干燥平衡所用时间越短;Exponential模型能较好的模拟鸡粪的干燥过程;在中低温条件下,根据Fick定律得到2~6 cm粪层厚度鸡粪的有效扩散系数在2.25×10–7~2.35×10–6 m2/h间;用正交试验得到鸡粪中低温干燥时效率最高的工艺为:干燥温度55℃,粪层厚度6 cm,风速1.2 m/s,该工艺下鸡粪的干燥效率为0.47 h/g。
The poultry industry in China is developing. The estimated flock in 2017 was over 1.4 billion hens with a yearly manure output of 56 million tons. Such a large amount of poultry manure has a tremendous pressure on environment because of the associated air, water and soil pollution. Environmental and health problems such as odor and pathogens can be eliminated by decreasing the moisture content of poultry manure. Thermal drying has been proven to be an effective method to remove moisture. Drying at middle-low temperature can not only save energy but also reduce the emission of ammonia compared with traditional drying method at high temperature. Middle-low temperature heat sources, such as solar energy and warm weather in-house, can be used to dry poultry manure. Furthermore, dried manure can be utilized as a raw material to produce organic fertilizer. In order to study the drying characteristics of poultry manure at middle-low temperature, drying experiments of poultry manure were carried out in a temperature-controlled drying oven. The effects of drying temperature,manure thickness and air speed on manure moisture ratio and drying rate were examined. After that, common drying models were applied to simulate the drying process. The optimization of the middle-low temperature drying parameters was also performed by orthogonal test. The result showed that the middle-low temperature drying process of poultry manure could be divided into 2 falling rate periods： The first falling rate period and the second falling rate period. The removed water in the first stage was mainly free water, the removed water in the second stage was mainly the capillary water, adsorption water and bound water, and the drying rate in the second stage was lower than that in the first stage. With the increasing of temperature,the decreasing of thickness, and the increasing of air speed, the appearance of inflection point became earlier and the drying time became shorter. Exponential model was more suitable for describing the poultry manure dry
作者
李绚阳
李保明
郑炜超
魏永祥
张智
Li Xuanyang;Li Baoming;Zheng Weichao;Wei Yongxiang;Zhang Zhi(College of Water Recourses ＆ Civil Engineering, China Agricultural University, Beijing 100083, China;Key Lab of Agricultural Engineering in Structure and Environment, Ministry of Agriculture and Rural Affairs, Beijing 100083, China;Beijing Engineering Research Center for Livestock and Poultry Healthy Environment, Beijing 100083, China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2018年第10期194-199,共6页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家蛋鸡产业技术体系(CARS-40)
