不同污泥颗粒的干燥特性分析

Study on the drying property of different sludge particulate

选取典型的生活污水污泥和造纸污泥进行干燥特性分析,对比了干燥过程中的水分析出特性、污泥球体中心温度变化和物理性质变化。结果表明,无论是生活污水污泥还是造纸污泥,在干燥过程中等速干燥阶段都不明显,而造纸污泥更快达到最大干燥速率,更快进入降速干燥阶段;造纸污泥球的中心温度在高温(>250℃)干燥条件下还存在超温的现象,即污泥球中心温度在某段时间内高于干燥温度,形成了蓄热内核;干燥过程中,造纸污泥水分的析出是依靠层层传递,污泥球结构稳定收缩,缩容率相对较小,最终收缩成一硬核;生活污水污泥在干燥中缩容率相对较大,水分析出伴随着外壳的破裂,内层与外界可直接进行热传递交换,干燥后结团性能差,疏散度高,不易定型。

The drying property of typical sewage sludge and paper mill sludge was analyzed and compared from dewatering characteristics and central temperature of sludge during drying process as well as the physical properties of dried sludge. Results showed that the constant-rate drying stage was not obvious for both paper mill sludge and sew- age sludge＋ paper mill sludge reached the maximum drying rate faster and entered into deceleration drying stage more quickly. Over-temperature was found during the high-temperature drying （〉 250 ℃）of paper mill sludge, at this point,the center temperature of sludge pellet was higher than the drying temperature and regenerative kernel was formed. The dewatering of paper mill sludge was started from interior to exterior, the sludge pellet shrunk steadily with small shrinkage rate, and sludge pellet was eventually formed into a hardcore. While for sewage sludge, the shrinkage rate was relatively large, sludge shell cracked during dewatering process, the heat transfer between inner sludge and outside occurred directly,the cluster performance dried sludge was poor.