脱水污泥热干化和微波干化过程及机理比较分析

Process and Mechanism Comparative Analysis of Dewatered Sludge's Thermal Drying and Microwave Drying

以脱水污泥为原料,分别采用恒温热干化和微波干化2种不同的方法考察脱水污泥的干化情况;对不同干化阶段的污泥进行显微观察,分析干化过程;并对2种干化过程的机理进行了探讨。实验结果表明随着加热温度的升高,污泥中水分脱除速度加快。加热温度低于100℃时,在120 min以内,热干化无法达到较高的脱水率。加热温度在140℃以上,加热时间120 min时,脱水污泥的脱水率可达到98.26%。微波干化法在功率为500~900 W,5~10 min内可使脱水污泥的脱水率到达99.20%以上。机理分析表明热干化传质与传热方向相反,微传热和传质的方向相同,因此微波干化具有更快速、高效的特点。

In order to investigate dewatered sludge drying process and its mechanism,the thermal drying method and microwave drying method are used to detect the relationship between dehydration rate and drying conditions.The drying process is observed by microscope. The results show that dewatered sludge moisture removal is sped up with the increase of heating temperature. When heating temperature is below 100 ℃, the thermal drying process can not attain a higher dehydration rate within 120 minutes. When heating temperature is above 140℃ and heating for 120 minutes,the dehydration rate of dewatered sludge can come up to 98.26%. Under conditions from 500 to 900 w within 5 to 10 minutes, the dehydration rate of dewatered sludge,by method of microwave drying, could reach above 99.20%. Via mechanism analysis, it is suggested that mass transfer and heat transfer directions of thermal drying method are opposite while the mass transfer and heat transfer directions of microwave drying process are consistent.Therefore, microwave drying process has the characteristics of fast and high efficiency.