污泥掺烧对燃煤电厂痕量元素排放特性影响

采用EPA Method 29方法、冷原子吸收光谱法和电感耦合等离子体质谱法采集和分析一台超低排放燃煤机组污泥掺烧前后的原燃料、烟气和副产物样品中各痕量元素浓度，研究污泥掺烧对燃煤电厂痕量元素排放特性的影响.结果表明：污泥中富含Zn、Cu元素，浓度分别是煤样中的18.81倍和17.64倍.污泥掺烧使掺配后入炉煤中痕量元素含量普遍升高.污泥掺烧前后整个系统、锅炉系统和全流程大气污染控制设施的痕量元素质量平衡率均在可接受范围内.污泥掺烧对痕量元素的分布特征无明显影响，随粉煤灰排放是痕量元素的主要排放去向.通过烟囱排放到大气环境的痕量元素排放量占比很小，不超过0.43%.污泥掺烧前后SCR入口烟气中痕量元素除Hg外主要以颗粒态形式存在.污泥掺烧后各痕量元素在粉煤灰和底渣中的相对富集系数未显著改变.经过全流程大气污染控制设施协同控制后，污泥掺烧前后烟囱总排口痕量元素排放浓度分别为0~12.76，0~14.97μg/m³.污泥掺烧后痕量元素排放浓度均满足美国燃煤发电机组有害大气污染物排放标准、上海市燃煤耦合污泥电厂大气污染排放标准和生态环境部生活垃圾焚烧污染控制标准的限值要求.现有的燃煤电厂大气污染控制系统对6%污泥掺烧比工况下痕量元素排放的控制具有较好的适应性.

Influence of sludge co-combustion on trace element emission characteristics in a coal-fired power plant

Sampled by EPA Method 29 and analyzed by Cold Atomic Absorption Spectroscopy and Inductively Coupled Plasma Spectroscopy, the concentrations of trace elements in the raw fuels, flue gas and by-product samples before and after sludge co-combustion in an ultra-low emission coal-fired unit were obtained, with the influence of sludge co-combustion on the emission characteristics of trace elements being investigated. The concentrations of Zn and Cu elements in sludge were high, which was 18.81times and 17.64times than that in the coal samples, respectively. The content of trace elements in the coal fed into the furnace after sludge co-combustion was generally increased. The mass balance rates of trace elements in the whole system, boiler system and air pollution control facilities of the whole process before and after sludge co-combustion were all within the acceptable range. The co-combustion of sludge had no obvious effect on the distribution characteristics of trace elements, and discharging with fly ash was the main emission pathway for trace elements. The proportion of trace elements emitted to the atmosphere through the stack was very small, no more than 0.43%. Except for Hg, the trace elements in the flue gas in the SCR inlet before and after sludge co-combustion mainly existed in the form of particles. The relative enrichment coefficients of trace elements in fly ash and bottom ash did not change significantly after sludge co-combustion. After the coordinated control of the whole-process air pollution control facilities, the emission concentrations of trace elements in the stack outlet before and after sludge co-combustion were 0~12.76μg/m³ and 0~14.97μg/m³, respectively. The emission concentrations of trace elements after sludge co-combustion meet the requirements of the US emission standards for harmful air pollutants from coal-fired generating units, the air pollution emission standards for coal-fired coupled sludge power plants in Shanghai, and the Ministry of Ecology and Environment's domestic waste incineration pollution control standards. The existing air pollution control system in coal-fired power plants had good adaptability to the emission control of trace elements under the condition of 6% sludge co-combustion ratio.