污泥低温干燥特性与参数优化
发布时间：2019-04-16 18:41
【摘要】：我国污泥产量巨大,污泥作为污水处理的剩余产物,具有含水率高、易腐烂、有恶臭等特点,并含有大量的微生物、寄生虫以及重金属。若不加合理处理处置,对环境将带来严重的二次污染。传统的污泥处置方式如填埋、堆肥、土地利用、建材利用以及焚烧均要求降低污泥含水率。热干燥是降低污泥含水率的有效途径。传统的污泥热干燥技术具有设备投资大、能耗高、运行费用高、存在爆炸风险以及产生二次污染等缺点。污泥低温热干燥技术作为一种新兴的干燥技术,具有节约能耗、减少恶臭气体、保存污泥热值、干燥过程安全等优势。为研究100℃以内的污泥低温干燥特性,搭建了污泥低温热风干燥试验装置。整个装置主要包括干燥箱、加热管、温度控制系统、数据采集装置、电力控制柜、高压风机等组成。经过对部分装置的重新设计和相关设备的选型,该试验装置具有结构紧凑、操作简便、节约成本等特点。对不同温度、薄层厚度以及风速下的污泥低温干燥特性进行了试验研究,结果表明:污泥在低温干燥过程中会产生明显的收缩和裂纹;干燥温度越高、薄层厚度越小以及热风风速越大,污泥低温干燥时间越短;低温干燥过程可以分为升速阶段、恒速阶段和降速阶段;整个干燥过程以降速阶段为主,约占总干燥过程的2/3;降速阶段存在较明显的第一和第二降速阶段,且第一临界含水率和第二临界含水率分别约为2.0g/g和0.5g/g(干基);与传统的薄层干燥模型相比,新模型MR=aexp(-ktn)+b描述污泥低温干燥过程的效果最优;Weibull分布函数可以准确地拟合污泥低温干燥过程,干燥温度、薄层厚度以及风速对尺度参数α有显著影响,形状参数β仅受干燥温度的影响较明显。在热风风速0.6m/s,干燥温度50~90℃的条件下,5、10和15mm薄层厚度污泥的水分有效扩散系数和活化能分别为:8.72×10-10~3.61×10-9、1.41×10-9~5.22×10-9、2.46×10-9~9.69×10-9m2/s和25.25、25.28和23.96kJ/mol。在干燥温度70℃、热风风速0.4和0.8m/s的条件下,薄层厚度10mm的污泥水分有效扩散系数为2.46×10-9和4.48×10-9m2/s。通过3因素3水平的正交试验,得到相对单位能耗最佳工艺组合为干燥温度90℃、风速0.8m/s、厚度10mm,平均干燥强度最优工艺组合为干燥温度90℃、风速0.8m/s、厚度5mm。本试验结果为后续研究污泥太阳能与热泵联合干燥提供参考。
[Abstract]:The sludge of our country has the characteristics of high moisture content, perishable, odor and so on. It contains a large number of microorganisms, parasites and heavy metals as the residual product of sewage treatment. The sludge has the characteristics of high water content, perishability, odor and so on. If not properly disposed of, will bring serious secondary pollution to the environment. Traditional sludge disposal methods, such as landfill, composting, land use, building material utilization and incineration, all require the reduction of sludge moisture content. Thermal drying is an effective way to reduce the moisture content of sludge. The traditional sludge heat drying technology has many disadvantages, such as large equipment investment, high energy consumption, high operation cost, explosion risk and secondary pollution. As a new drying technology, low temperature thermal drying of sludge has many advantages, such as saving energy consumption, reducing odor gas, preserving sludge calorific value and safety of drying process. In order to study the low temperature drying characteristics of sludge under 100 鈩，
本文编号：2459002
[Abstract]:The sludge of our country has the characteristics of high moisture content, perishable, odor and so on. It contains a large number of microorganisms, parasites and heavy metals as the residual product of sewage treatment. The sludge has the characteristics of high water content, perishability, odor and so on. If not properly disposed of, will bring serious secondary pollution to the environment. Traditional sludge disposal methods, such as landfill, composting, land use, building material utilization and incineration, all require the reduction of sludge moisture content. Thermal drying is an effective way to reduce the moisture content of sludge. The traditional sludge heat drying technology has many disadvantages, such as large equipment investment, high energy consumption, high operation cost, explosion risk and secondary pollution. As a new drying technology, low temperature thermal drying of sludge has many advantages, such as saving energy consumption, reducing odor gas, preserving sludge calorific value and safety of drying process. In order to study the low temperature drying characteristics of sludge under 100 鈩，
本文编号：2459002
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