利用生活垃圾焚烧电厂余热协同处置市政污泥

Collaborative disposal of sewage sludge using waste heat from municipal solid waste incineration

以苏州市市政污泥为研究对象,利用生活垃圾焚烧发电厂的余热进行污泥干化实验,对污泥的热值特性、干化及含水率变化特性、焚烧温度、灰渣重金属浸出特性等进行研究。结果表明,样品污泥中的重金属元素含量超过土地利用以及污泥农用的相关标准,不能将其直接农用;污泥干化过程中随着污泥含水率逐渐下降,干化速率先平稳上升,再快速下降,然后略有升高,但整体呈下降趋势,该波动与污泥干燥过程的湿区、黏滞区和粒状区存在对应关系;污泥的平均低位热值与其含水率呈反相关,当污泥干化至含水率30%,低位热值为7345 kJ/kg,可满足入炉焚烧要求;污泥的焚烧温度主要取决于污泥的含水率,焚烧后的飞灰和炉渣中重金属浸出毒性均未超过国家标准规定的限值,可进行综合利用。

This work analyzes the application background of municipal sludge collaborative disposal by municipal solid waste(MSW).The differences between sludge incineration and landfill were compared.Sewage sludge of Suzhou as the research object,sludge drying experiment was carried out by using the waste heat of domestic garbage incineration power plant.The water content characteristics,heavy metal content and elemental content of sludge sample were tested.The calorific value characteristics,drying and combustion characteristics including combustion temperature and heavy metal leaching were investigated.Results indicated that heavy metal elements of sludge sample exceed the relevant standards for landfilling and agricultural utilization,and the municipal sludge cannot be used directly for agriculture.As the decreasing of water,with the water content decreasing gradually,the drying rate first rises steadily,then decreases rapidly,and rises slightly,but the overall trend is downward.The fluctuation is corresponding to the three drying areas,that are wet area,viscous area,and particle area.The average low calorific value has a significant upward trend with the decrease of water content.The low calorific value reached 7345 k J/kg when the water content is 30%,which meats the requirement of incineration.Through combustion treatment,the leaching toxicity of heavy metals in the ash and slag of sludge are within the national standard.Thus,the ash and slag after sludge incineration can be used comprehensively.