市政污泥混合干燥中干湿包裹的特性研究

Dry and Wet Wrapping Characteristics of Municipal Sludge Mixing Drying

污泥干湿混合可以降低含水率、降低粘性、提高干燥效率。在干、湿污泥质量比(干湿比)为1∶2~1∶7的范围内,对常规混合、湿污泥包裹干污泥(湿包干)、干污泥包裹湿污泥(干包湿)在105℃下进行了恒温干燥试验。结果表明,湿包干污泥颗粒的干燥效果比干包湿污泥颗粒的好,非混合污泥的干燥效果比干包湿的要好;湿包干的干燥效果最佳时的干湿比为1∶4,这是因为干燥过程中水分存在由外向里的逆向传质,是传质和传热共同作用的结果。

efficiency of slu Mixing dry and wet sludge could reduce moisture and decrease viscosity to improve the dge drying. With the mass ratio of dry and wet sludge between 1 ： 2 and 1 ： 7, a series of sludge drying experiments were carried out under 105 ℃ temperature, including conventional mixing, wet sludge wrapping dry sludge, and dry sludge wrapping wet sludge. The results showed that drying efficien- cy of wet sludge wrapping dry sludge was better than dry sludge wrapping wet sludge. The conventional sludge showed better drying efficiency than dry sludge wrapping wet sludge. In conclusion, the drying efficiency of wet sludge wrapping dry sludge was best at a ratio of 1 ： 4. It was because that the direction of moisture migration was from outside to inside, which was a combined outcome of mass transfer and heat transfer.