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城市生活污泥干化方法研究
Study on the Drying Methods of Municipal Sludge
【作者】 王磊；
【作者基本信息】 合肥工业大学 ， 环境工程， 2010， 硕士
【摘要】 随着我国污水处理率的逐年提高,污水处理过程中产生的城市生活污泥量日益增加,污水污染问题引发了污泥污染问题。为避免二次污染并有效利用城市生活污泥中的有效成分,污泥处理己经成为全世界关心的问题。目前城市生活污泥处理方式主要有填埋、焚烧、堆肥等。但无论何种方法都必须经过干化这一环节,如何经济、高效地干化城市生活污泥己成为污泥处理的重要课题。论文以研究高效、经济的城市生活污泥干化工艺为目标;利用烘箱加热系统对影响城市生活污泥干化效能的因素进行了研究,探讨了污泥干化的机理;并对干化系统的耗能进行了计算;此外,利用自制的太阳能干化装置对城市生活污泥的太阳能干化影响因素进行了研究,并在此基础上对装置进行了一系列的改进,设计出更合理的污泥太阳能干化装置,并对相关运行参数和干化成本进行了计算。研究得出以下主要结论:(1)污泥烘箱干化过程中,干化速率可分为三个阶段:加速阶段、恒速阶段和降速阶段,其中恒速阶段占整个干化时间的50%以上,加速阶段仅占了15%,污泥含水率的去除主要集中在恒速阶段。(2)污泥烘箱干化过程中,当干化温度相同时,污泥的厚度越薄、干化速率越快,泥饼厚度为1.0cm时,干化效果最佳;泥团的直径越小,干化速率越快,泥团直径为1.0cm时,干化效果最好。当干化温度不同时,得出直径为1.0cm的泥团在120℃时,最经济,干化效果最好。(3)污泥的太阳能干化实验中,温度越高,湿度越低,干化效率越高,以厚度为2.0cm的泥饼为例,在夏季(太阳辐射照度为14.8千卡/平方厘米)和冬季(太阳辐射照度为7.5千卡/平方厘米)的干化速率最大值分别为45g/h和6g/h,夏季干化速率明显高于冬季,达到相同干化效果(含水率60%)所需时间分别为1.2天和7.2天。(4)利用烘箱和太阳能-热尾气联合干化装置进行污泥干化,达到相同干化效果(含水率60%)所需成本分别为187.5元/吨,2.4元/吨,污泥的太阳能-热尾气联合干化较烘箱干化有明显的成本优势。上述研究结果将对城市生活污泥热干化以及太阳能干化的的工程实践提供科学依据,具有一定的指导意义。
【Abstract】 As the ratio of sewage water treatment in our country increases year after year, municipal sludge volume brought by the sewage treatment process grows larger, thus sewage pollution results in the formation of sludge pollution. Sludge treatment and disposal has become one of the most important tasks for environmental protection in order to prevent consequent pollution and make effective use of municipal sludge. There are three sludge disposal methods currently used, which is recycling in agriculture, land filling and incineration. Each of them needs the drying technology. How to dry the municipal sludge economically and efficiently has become an important topic in the science field.The paper mainly targets at investigating municipal sludge drying technology which was efficient, economical. Using the drying box heating system studies on the factors influenced over the drying efficiency of municipal sludge drying, explores the mechanism of sludge drying, and calculates the energy consumption of the sludge drying system. In addition, using home-made solar drying device studies on the factors influenced over municipal sludge drying, and which were based on improving a series of equipment for designing more rational solar sludge drying device, and calculates the relevant operating parameters and drying costs. The following is the main conclusion of the research:(1) During the course of drying sludge by the drying box, the drying rate can be divided into three phases: acceleration phase, constant rate drying phase and falling rate drying phase, the phase of distinctive characteristics: constant rate drying phase accounts for more than 50 percent of the total drying time, the acceleration phase accounts for only 15 percent, so moisture content removal of the municipal sludge mainly in constant rate drying phase.(2) During the course of drying sludge by drying box, when the drying temperature is the same, the thinner thickness of the municipal sludge, the faster drying rate, 1.0cm thickness of the mud cake, the drying effect is best; the smaller diameter of the sludge particle, the faster drying rate, 1.0cm diameter of the sludge particle, the drying effect is best. When the drying temperature is different, come to 1.0cm diameter of the sludge particle on condition that the drying temperature of 120℃, the drying effect is best and the most economical. (3) During the municipal sludge Solar drying experiment, the higher the drying temperature and the lower the humidity, the higher the efficiency of drying. To the 2.0cm thickness of the mud cake for example, the summer (solar radiation intensity of 14.8 kcal per square centimeter) and the winter (solar irradiance of 7.5 kcal per square centimeter) of the maximum rate of drying were respectively 45g per hour and 6g per hour, the drying rate in summer was significantly higher than it in winter, achieving the same effect of drying (moisture content 60%) time were respectively 1.2 days and 7.2 days.(4) Using drying box and solar-hot exhaust joint drying sludge device, to achieve the same effect of drying (60% of moisture content), respectively the cost is 187.5 Yuan per ton, 2.4 Yuan per ton, the cost of solar-hot exhaust joint drying sludge far less than the drying box drying.Results above provided scientific basis for engineering practice of sludge heat-drying and solar energy drying, and has some guided significance.