鸡舍换气余热干燥鸡粪设备夏季干燥性能研究

鸡舍换气余热干燥鸡粪是指利用鸡舍换气时排出废气的余热来除去鸡粪中水分的热力干燥方法,该方法的主要特点为工艺简单、能耗低。该文主要对鸡舍换气余热干燥鸡粪的原理进行了阐述,探讨了鸡粪干燥过程中各种热量的计算方法,并针对中国的气候特点,结合鸡舍换气余热干燥鸡粪设备设计改造了一种可在夏季利用环境空气对鸡粪进行干燥的通风方式,最后对湖北应城的一套鸡粪干燥设备(manure drying system,MDS)进行了夏季应用效果的测试。结果表明:夏季不同天气条件下干燥设备的干燥速率差异较大;晴天天气下由于外界环境空气的混入,鸡粪含水率从初始含水量降至28%(湿基)耗时只需28 h左右,比阴雨天气下缩短约20 h;夏季阴雨天气下鸡舍换气余热可满足48 h内把鸡粪含水率降至30%以下的热量需求,但阴雨天气会降低鸡粪的干燥速率。晴天天气下由于湿帘的影响,鸡舍所排废气湿度过大,此时可结合环境热空气对鸡粪进行干燥,提高鸡粪干燥速率。研究结果可为优化鸡粪干燥工艺,探索节能环保的干燥方法提供理论参考。

Drying performance of manure drying system with waste heat of poultry house in summer

A large amount of poultry manure is produced yearly in China, which has become a tremendous pressure on the environment when it cannot be utilized as resources. Improper or untimely handling method of manure can result in massive discharge of ammonia, which is a major source of air pollution. Manure can also serve as a breeding ground for pathogenic microorganisms as well as a medium for disease transmission among birds. It is necessary to subject poultry manure to suitable treatments including storage and handling in order to minimize the risk of disease transmission and environmental pollution. The environmental problems can be eliminated by decreasing the moisture ratio of poultry manure to minimize its decomposition rate and the dried poultry manure can be utilized as a raw material to produce organic fertilizer. Thermal convective drying has been proven to be an effective method to remove moisture from poultry manure. Using waste heat of poultry house to dry poultry manure refered to the thermal drying method of removing water in poultry manure, which was mainly characterized by low energy consumption. This drying method could be a proper method to deal with poultry manure in China. This paper mainly expounded the working principle of heat recovery of exhaust air from poultry house. Based on the principle of heat balance in poultry house, this paper explored heat calculation methods in the process of poultry manure drying, and ventilation methods for drying poultry manure in summer were designed. In the end, the application effect of the poultry manure drying system installed in Yingcheng was tested. The results showed that the drying efficiency of drying equipment varied greatly under different weather conditions in summer. Under the rainy weather, the waste heat of poultry house can meet the heat demand of reducing the water content of poultry manure to below 30% within 48 hours. In sunny weather, when the waste air from poultry house mixed with ambient air, it took about 28 hours to reduce the water of poultry manure, the end water content was decreased to 28%, which was 20 hours shorter than under rainy weather. In sunny weather, the enthalpy of ambient air decreased after it is discharged from the poultry house because of the wet curtain, at this time, if the ambient air can be used to dry poultry manure directly, and the drying rate will be improved. The sunny days in southern China are more abundant solar radiation in summer, hot ambient air is a suitable heat sources to dry poultry manure. Using hot ambient air can also solve the problem of excessive humidity in exhaust air from poultry house. Finally, according to the test results, the control scheme of reasonable utilization of exhaust air from poultry house and ambient air was proposed. The results provide an analytical reference to improve poultry manure drying efficiency and explore the ways of energy saving drying, as well as provide a reference to design the poultry manure drying process system.