超声波处理对污泥热风干燥过程的影响  

Effect of ultrasonic treatment on hot air drying process of sludge

作　　者：赵芳[1] 程道来[1] 陈振乾[2] 

机构地区：[1]上海应用技术学院城市建设与安全工程学院,上海201418 [2]东南大学能源与环境学院,南京210096

出　　处：《农业工程学报》2015年第4期272-276,共5页Transactions of the Chinese Society of Agricultural Engineering

基　　金：上海高校青年教师培养资助计划(ZZyyy13006);高校博士点基金资助项目(20090092110005);上海应用技术学院人才引进项目(YJ2013-47)

摘　　要：为了探讨超声作用对污泥热风干燥过程的强化效果,对不同功率超声作用下污泥热风干燥特性进行试验研究,分析讨论了超声声能密度、超声作用时间、超声热效应等因素对污泥干燥过程的影响。试验结果表明,超声作用可以加速污泥干燥速率,且超声强化效果随着声能密度的增加逐渐增强。当热风温度为80℃,声能密度分别为0.2、0.4、0.6、0.8及1.0 W/m L时,污泥样品干基含水率降至100%所需干燥时间与无超声作用时相比分别缩短了8.3%、22.9%、33.3%、37.5%及39.6%。此外,超声作用时间不宜过长,超声声能密度0.8 W/m L持续作用2 h后,进一步增强超声作用时间对污泥干燥过程的强化效果已不明显。超声热效应使样品内部的温度梯度略有减小,因此超声作用没有强化污泥内部由温度梯度引起的水分扩散。Solid–liquid separation is crucial for reduction and recycling disposal of sludge, and ultrasonic treatment is regarded as one of the most potential and effective method for improving dewaterability. In order to investigate the effect of ultrasonic treatment on hot air drying process of sludge, an experimental apparatus for ultrasound-assisted hot air drying of sludge was designed and built. The experimental apparatus were composed of hot air generator, ultrasonic generator and transducer,data acquisition system and drying chamber. The ultrasonic apparatus operated at a frequency of 20 k Hz and supplied a continuous adjustable power of 0-600 W. The hot air temperature was respectively set at 60, 80, 100, 120℃, a drying experiment was performed to analyze hot air drying characteristic of sludge under different acoustic parameters and to assess the effects of ultrasonic energy density, irradiation time and ultrasonic thermal effect on hot air drying process of sludge. Results showed that ultrasonic treatment can accelerate drying process, and the ultrasonic enhancing effect on sludge drying process gradually strengthened with the increase of ultrasonic energy density. When sludge sample thickness was 15 mm, hot air temperature and velocity was 80℃ and 1.0 m/s, the dry basis moisture content of sample reduced to 100% after drying 4.8 hours without ultrasonic treatment. When hot air temperature was 80℃ and ultrasound energy density was 0.2, 0.4, 0.6, 0.8 and 1.0 W/m L, respectively, the drying time of moisture content of sludge decreasing to 100% were shortened by 8.3%, 22.9%, 33.3%, 37.5% and 39.5%, respectively, compared with that under untreated ultrasound. The ultrasonic treatment has no obvious effect on sludge drying process after 2 hours at ultrasonic energy density of 0.8 W/m L and hot air temperature of 80℃. Thus there is no need to keep on the ultrasonic treatment anymore after this time. Moisture content of sample has an important influence on ultrasonic enhancement effect on sludge drying proces

关 键 词：超声波 干燥 污泥处理 热风干燥 热效应 

分 类 号：TK124[动力工程及工程热物理—工程热物理]