采用HAPSITE便携式气相色谱/质谱仪、盐酸萘乙二胺分光光度法等检测废气成分,研究了水泥窑处置城市污水污泥烘干过程中废气的污染与防治。实验结果表明,含水量较高的城市污水污泥烘干时会产生恶臭气味的尾气,其成分包括NH3、S和芳香族化合物、卤代烃等,直接排放会污染环境。以新鲜热风烘干污水污泥后的废气与煤粉在950℃燃烧,不仅可分解废气中多种有害组分,而且还可降低废气NOXH2浓度。利用窑尾废气直接烘干污泥的技术方案值得商榷,建议采用回收水泥回转窑筒体冷却热风或熟料冷却机热风烘干污水污泥,其废气再进入水泥窑燃烧的技术方案。
Contamination and prevention of drying waste gas during processing municipal sewage sludge in the cement kiln were investigated, utilizing HAPSITE portable gas chromatograph/mass spectrometer and N(1-naphty1)-ethylene diamine dihydrochloride spectrophotometric method to measure the waste gas composition. The results show that, offensive odor off-gases are produced from the municipal sewage sludge with a high moisture content during the drying process, the composition of which includes ammonia, hydrogen sulfide, aromatic compounds, halohydrocarbon and so on and the direct emission of which contaminates the environment. The waste gas, from sewage sludge drying using the fresh hot air, can combust with pulverized coal at 950℃, which not only leads to the decomposition of several harmful components in the waste gas but also reduces the NOx concentration. The approach to directly dry the sludge with kiln back-end waste gas is questionable. It is suggested that the hot gas from cement rotary kiln shell cooling or the clinker cooler is recovered and used to dry sewage sludge, following which the waste gas enters the kiln for combustion.