污水厂污泥与生物质混合干燥特性研究

发布时间：2018-05-05 09:39

本文选题：污水厂污泥 + 生物质　；参考：《天津科技大学》2015年硕士论文

【摘要】：随着我国城镇化水平的加快,城镇污泥处理量的增大,需要安全处理处置的污泥量也日益增大,热干化是一种比较有效和环保的污泥处理方式,热干后的污泥可填埋、制作农业肥、园林和建材利用、或直接焚烧,从而实现污泥安全处置的减量化、稳定化、无害化、资源化要求。污泥热风对流干燥是目前热干化一种主要形式；但干燥过程中污泥容易团聚收缩,增加内部水分向表面扩散阻力,导致了污泥热风干燥时间长,能耗高。针对污泥干燥收缩增加传质阻力难题,课题提出一种利用生物质改善污泥热风干燥特性的设想：即在湿污泥内添加一定量的输送生物质颗粒,以改变污泥内部结构,增加孔隙率和内部水分扩散通道,减低干燥过程传质阻力,从而提高污泥热风干燥速率。另外,湿污泥热值低,不能自持燃烧；添加生物质提高了湿污泥热值,使之自持燃烧。课题主要对污泥和生物质混合干燥特性,工艺参数影响,干燥数学模型,以及干燥产物的热解和焚烧特性进行实验研究和分析,以期为了解生物质和污泥共混干燥工艺提供一些基本知识和技术数据。本课题主要内容如下：(1)污水厂污泥和生物质共混干燥特性。利用自制污泥热风干燥试验台,对污泥和生物质干燥过程进行实验,研究了混合物干燥特性以及工艺参数对干燥过程的影响。实验结果表明木屑和麸皮添加有利于缩短污泥干燥时间；实验条件下,木屑添加可使污泥干燥时间减半。(2)污泥和生物质共混干燥数学模型。在实验数据基础上,分别建立污泥混合干燥运动学模型,以及考虑体积收缩的干燥动力学数学模型。生物质如木屑添加提高了污泥水分扩散系数,降低了干燥活化能。(3)污泥和生物质干产物的热解和燃烧特性。使用热重分析仪,分别在氮气和空气气氛下测定污泥混合物热解和燃烧特性,分析计算了污泥与生物质混合物的各项燃烧指数,发现污泥降低了生物质的着火点,生物质提高了污泥的可燃性指数、稳燃性指数以及综合燃烧指数。
[Abstract]:With the acceleration of urbanization in our country and the increase of sludge treatment capacity in cities and towns, the amount of sludge that needs safe treatment and disposal is also increasing day by day. Thermal drying is a more effective and environmentally friendly way of sludge treatment, and the sludge after hot drying can be landfill. To make agricultural fertilizer, garden and building materials, or incinerate directly, so as to realize the requirements of reducing, stabilizing, innocuous and resource utilization of sludge safety disposal. Hot air convection drying of sludge is one of the main forms of hot drying at present, but sludge is easy to agglomerate and shrink during drying process, which increases the resistance of internal moisture diffusion to the surface, which results in long drying time and high energy consumption of sludge. In view of the difficult problem of increasing mass transfer resistance by sludge drying shrinkage, this paper proposes an idea of using biomass to improve the drying characteristics of sludge by hot air: adding a certain amount of conveying biomass particles to wet sludge to change the internal structure of sludge. Increase porosity and internal water diffusion channel, reduce mass transfer resistance during drying process, so as to improve the drying rate of sludge hot air. In addition, the low calorific value of wet sludge could not be burned on its own, and biomass increased the calorific value of wet sludge and made it self-sustaining combustion. In this paper, the characteristics of mixed drying of sludge and biomass, the influence of process parameters, the mathematical model of drying, and the pyrolysis and incineration characteristics of drying products are studied and analyzed. In order to provide some basic knowledge and technical data for understanding biomass and sludge blending drying process. The main contents of this paper are as follows: 1) drying characteristics of sludge and biomass blend in wastewater treatment plant. The drying process of sludge and biomass was studied by using a self-made hot air drying test rig. The drying characteristics of the mixture and the effect of process parameters on the drying process were studied. The results showed that the addition of sawdust and bran was beneficial to shorten the drying time of sludge, and under the experimental conditions, the drying time of sludge could be reduced by half. 2) the mathematical model of mixed drying of sludge and biomass was obtained. Based on the experimental data, the kinematic model of mixed drying of sludge and the mathematical model of drying dynamics considering volume shrinkage were established respectively. Biomass such as sawdust increased the moisture diffusion coefficient of sludge and reduced the pyrolysis and combustion characteristics of sludge and biomass dry products. The pyrolysis and combustion characteristics of sludge mixture in nitrogen and air atmosphere were measured by thermogravimetric analyzer. The combustion indexes of sludge and biomass mixture were analyzed and calculated. It was found that sludge reduced the ignition point of biomass. Biomass increased the combustibility index, combustibility index and combustible index of sludge.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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