污泥焚烧过程中铬等重金属的迁移转化特性研究

发布时间：2018-07-07 18:55

  本文选题：污泥焚烧 + 管式焚烧炉　； 参考：《浙江大学》2015年硕士论文

【摘要】：随着我国污水排放量的增大以及污水处理率的提高,污泥的产量日益增加。污泥焚烧因可以使污泥的减量率提高、破坏有机微生污染物、节能发电等优点而具有广泛的应用前景。由于污泥焚烧过程中排放的重金属对环境造成严重危害,制约了我国污泥焚烧工艺的发展和推广。本文采用实验方法,深入地探讨了污泥焚烧过程中铬等重金属的迁移转化特性。 建立污泥焚烧实验系统,主要分为配气系统、管式炉焚烧系统和烟气吸收系统三个部分。收集焚烧后的灰渣,对灰渣内重金属含量及状态进行测量,测量方式有电感耦合等离子体质谱(ICP-MS)、紫外-可见分光光度法、X射线衍射(XRD)和能谱仪(EDS)。 研究焚烧条件对铬及其他重金属迁移转化的影响,污泥焚烧时,改变焚烧温度、停留时间和焚烧气氛。焚烧温度设为500℃、600℃、700℃、800℃、900℃,随温度升高铬的挥发率增大,灰渣中Cr(Ⅵ)质量百分比由6.87%下降至3.60%,低温度时,灰渣中铬的化合物为Ca(CrO4)、Cr2O3、MgCr2O4,高温度时,化合物为Cr2O3、MgCr2O4, Cr(Ⅵ)化合物减少。随温度升高,Cd、Pb和Zn挥发率增大,而Ni的变化不大。停留时间范围设定为10min到100min,时间间隔为10min,随时间增加,铬的挥发率增大,灰渣中的Cr(Ⅵ)质量百分比增大后略有下降,随后稳定,Cd、Pb和Zn残留率降低,Ni略有增加。通入气流中氧气含量增加,铬的挥发率增大,促进灰渣中Cr(Ⅲ)向Cr(VI)转化,氧气过多后,Cr(Ⅵ)增多,随飞灰排入空气,灰渣内含量降低。 研究固体添加剂对铬及其他重金属迁移转化的影响,选择CaCl2、CaO、SiO2、 Al2O3、NH4Cl、(NH4)2SO4和(NH4)3PO4作为固体添加剂,实验数据表明,CaCl2、 CaO有利于Cr2O3向Ca(CrO4)转化,SiO2可以固定灰渣中的铬,降低其挥发性。NH4Cl、(NH4)2SO4和(NH4)3PO4促进铬的挥发,使灰渣中Cr(Ⅵ)含量降低。在于固体添加剂混烧时,CaCl2、CaO使As、Cd、Ni、Pb和Zn得挥发率增大。
[Abstract]:With the increase of sewage discharge and sewage treatment rate in China, sludge production is increasing day by day. Sludge incineration has a wide application prospect because of its advantages of increasing sludge reduction rate, destroying organic micro-pollutants and energy saving power generation. The development and popularization of sludge incineration technology in China is restricted by heavy metals discharged during sludge incineration. In this paper, the transport and transformation characteristics of chromium and other heavy metals during sludge incineration were studied by experimental method. The experimental system of sludge incineration is mainly divided into three parts: gas distribution system, tube furnace incineration system and flue gas absorption system. The content and status of heavy metals in incineration ash were measured by inductively coupled plasma mass spectrometry (ICP-MS), UV-Vis spectrophotometry, X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The effects of incineration conditions on the transport and transformation of chromium and other heavy metals were studied. During sludge incineration, the incineration temperature, residence time and incineration atmosphere were changed. The incineration temperature was set at 500 鈩，

本文编号：2105931