污泥过热蒸汽搅拌干燥机及两级联合干燥系统设计

发布时间：2019-05-30 03:40

【摘要】：随着我国经济社会快速发展和城镇化进程加快,污水排放量及污泥处理量逐年增多。污泥作为污水处理的副产物,富集了大量的重金属、致病菌、有机污染物等毒害物质,若不对其进行有效的处理处置,将对生态环境和动植物产生危害。污泥具有体量大、来源广、含水率高等特点,处理处置的关键在于降低其含水率。对污泥进行干燥是实现污泥无害化、稳定化、资源化目标的有效手段,污泥经干燥后减容显著,性状得到改善,有多重资源化利用途径。污泥干燥过程中的胶粘性是影响污泥干燥效果的主要因素之一,具体表现为污泥自身的粘结以及与干燥设备壁面粘附。干燥过程的胶粘性是多种因素共同作用的结果,主要包括有机物、含水率、干燥温度和加热方式等。解决污泥干燥胶粘性的技术方案众多,可通过调理剂预处理破坏污泥的内部结构,改变污泥水分的分布形式,以及设计相关的干燥工艺与设备,主要包括加热面阴极化、电渗透脱水预处理、干料返混工艺和自清式转轴等。为实现污泥高效节能干燥,采用过热蒸汽为干燥介质,结合搅拌干燥的优点,设计了污泥过热蒸汽搅拌干燥机。首先,介绍了干燥机设计的基础参数和设计要求,在此基础上做了总体结构设计;其次,设计了搅拌轴组件,包括叶片安装角的分析、搅拌轴结构设计与校核、双搅拌轴组件与单搅拌轴组件的对比分析及选择;第三,对搅拌机的壳体、联接装置等结构与功能进行了分析和设计,包括筒体、上盖、支撑件、端板、进出气口及轴端密封装置;最后,做了轴承配置的分析与选型,传动装置类型的选择与设计。综合考虑污泥的干燥速率、能量利用率、污泥胶粘特性及尾气处理等因素,设计了污泥两级联合干燥系统,主要由蒸汽发生器、温控系统、污泥进料装置、搅拌干燥机、双螺杆挤压机、逆流装置、换热器、网带式干燥机和尾气洗涤塔等组成。阐述了污泥两级联合干燥的流程和系统中各个部分的功能。在一级干燥系统中,污泥被搅拌干燥至较低含水率后送入双螺杆挤压机制成颗粒,部分乏汽输送至换热器;在二级干燥系统中,污泥颗粒在逆流装置中与干污泥粉末接触吸附,形成的污泥颗粒内湿外干,避免污泥粘结与粘附,换热器中形成的热风对输送至网带式干燥机的污泥颗粒进行低温干燥,降低污泥含水率,换热器和二级干燥系统中产生的尾气通入尾气洗涤塔处理后排放。
[Abstract]:With the rapid development of economy and society and the acceleration of urbanization in China, sewage discharge and sludge treatment capacity are increasing year by year. As a by-product of sewage treatment, sludge is enriched in a large number of heavy metals, pathogenic bacteria, organic pollutants and other toxic substances. If it is not effectively treated and disposed of, it will cause harm to the ecological environment and animals and plants. Sludge has the characteristics of large volume, wide source and high moisture content. The key to treatment and disposal is to reduce its moisture content. Sludge drying is an effective means to realize the goal of innocuity, stabilization and resource utilization of sludge. After drying, the capacity of sludge is significantly reduced, the characteristics are improved, and there are multiple ways of resource utilization. The stickiness in the process of sludge drying is one of the main factors affecting the drying effect of sludge, which is manifested in the bonding of sludge itself and the adhesion to the wall of drying equipment. The stickiness of drying process is the result of many factors, including organic matter, moisture content, drying temperature and heating mode. There are many technical schemes to solve the stickiness of sludge drying adhesive. The internal structure of sludge can be destroyed by conditioning agent pretreatment, the distribution form of sludge moisture can be changed, and the related drying processes and equipment can be designed, including negative polarization of heating surface. Electroosmotic dehydration pretreatment, dry material backmixing process and self-cleaning shaft, etc. In order to realize high efficiency and energy saving drying of sludge, a sludge superheated steam stirring dryer was designed by using superheated steam as drying medium and combining with the advantages of stirring drying. First of all, the basic parameters and design requirements of dryer design are introduced, on the basis of which the overall structure design is made. Secondly, the mixing shaft assembly is designed, including the analysis of blade installation angle, the structure design and check of mixing shaft, the comparative analysis and selection of double mixing shaft assembly and single mixing shaft assembly. Thirdly, the structure and function of mixer shell and connection device are analyzed and designed, including cylinder, upper cover, support, end plate, inlet and exit air port and shaft end sealing device. Finally, the analysis and selection of bearing configuration, the selection and design of transmission type are done. Considering the drying rate of sludge, energy utilization rate, sludge adhesive characteristics and tail gas treatment, a two-stage combined sludge drying system was designed, which was mainly composed of steam generator, temperature control system, sludge feed device and mixing dryer. Twin screw extruder, countercurrent device, heat exchanger, net belt dryer and tail gas washing tower. The process of two-stage joint drying of sludge and the functions of each part of the system are described. In the primary drying system, the sludge is stirred and dried to a lower moisture content and sent to the twin-screw extrusion mechanism to form particles, and some of the steam is transported to the heat exchanger. In the secondary drying system, the sludge particles are adsorbed in contact with the dry sludge powder in the countercurrent device, and the sludge particles are wet and dry inside and outside, so as to avoid the bonding and adhesion of the sludge. The hot air formed in the heat exchanger dries the sludge particles transported to the net belt dryer at low temperature, reduces the moisture content of the sludge, and emits the tail gas from the heat exchanger and the secondary drying system after being treated with the tail gas washing tower.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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