污泥卫生填埋场设计优化

Design Optimization for Dewatered Sewage Sludge Sanitary Landfill

污泥卫生填埋是其大批量快速无害化消纳的主流技术。本论文以Darcy定律为理论基础,建立集气井抽气条件下的污泥填埋气一维压力分布简易模型,并进一步确定竖井抽气系统的最佳影响半径,优化污泥填埋气竖井收集系统。集气井的服务半径Roi可达到10~11.5m。填埋气导气竖井采用穿孔导气管居中的石笼,导气管管底与渗滤液收集干管相连通,管顶露出改性污泥覆盖层表面1.0m。导气竖井由里到外依次为:Φ160mm的HDPE穿孔花管、0.64m厚的级配碎石填埋气导排层、钢丝格网、200gm^(-2)机织土工布、0.3m厚的矿化垃圾(或建筑垃圾)保护层和200gm^(-2)机织土工布。每个污泥填埋库区设置3个导气竖井,导气井间距为20~25m;各导气竖井出气口由水平软管相互连通后,集中输送至总气体收集井,再通过HDPE集气干管送至填埋气发电区;填埋气导气井出口和集气干管应安装阀门和甲烷检测端口。

Based on the theory of Darcy,a first order mathematical model was deduced to optimize landfill gas（ LFG）collection system. The radiuses of influence（ Roi） of vertical extraction well was found to be 10 ~ 11. 5m. The major components of landfill gas are methane and carbon dioxide with a member of minor constitutes. In order to control greenhouse gas emissions and minimize the risk of migration of landfill gas,effective extraction systems must be developed. The collection system（ e. g. vertical extraction well） comprises vertical gas well（ Φ160mm HDPE）,wellheads,and collection pipe. The vertical well has perforations over the lower part of pipe length,and is surrounded by a suitably sized aggregate fill（ 0. 64 m thickness） and a composite protective layer（ including steel wire gauze,200 g/m2 woven geotextile,0. 3m-thickness aged refuse or construction waste,and 200g/m2 woven geotextile）. The welding between HDPE geomembrane and perforated pipe should be performed to prevent air admission. Vertical gas wells are normally spaced between 20 m and 25 m part,with 3 wells in a landfill unit; the collected landfill gas is then conveyed via the collection pipe network to the point of thermal destruction（ e. g. flare unit） or energy production. The recovery of landfill gas as an energy resource can compensate the part of the costs of sludge disposal,but the potential depends upon the methane content of the gas. Normally,the purification of gas should be taken into account prior to entering generator set.