城市生活垃圾填埋场气压分布一维稳态分析模型

掌握填埋场气压分布是填埋气灾害控制和资源化利用的基础。提出了分层垃圾填埋体气压分布一维稳态分析模型及求解方法。该模型可分析含有给定抽气压力或给定抽气流量水平导气层的填埋体气压分布。采用该模型探讨了垃圾分层特征、封顶覆盖层下和填埋体内的高渗透性水平导气层、填埋体底部渗沥液导排系统兼作填埋气导排通道对填埋体气压分布的影响规律。通过参数分析得到以下结论：填埋体垃圾不考虑产气速率和固有渗透系数随垃圾埋深增加而减小（产气速率和固有渗透系数按埋深平均）会高估填埋体内气压;封顶覆盖层下和填埋体内设置水平导气层可有效降低填埋体内气压;填埋体底部填埋气导排通道对填埋气气压较大的深部垃圾降压效果较明显。分析结果表明,该模型可指导填埋气收集系统设计,如水平导气层位置和间距布置及抽气功率选择等。

One-dimensional Steady-state Model for Gas Pressure Distribution in Municipal Solid Waste Landfills

Gas pressure distribution in landfills is of great importance to control hazards and improve recovery of landfill gas. An one-dimensional steady-state model and its solving approach are presented for gas pressure distribution in layered waste landfills. The model can be used to investigate the gas pressure distribution of the landfill with horizontal gas collection layers having specified pressure or flux. The influences of layered properties, horizontal permeable layer under final cover and horizontal gas collection layers and bottom leachate drainage systems dually serving as gas collection layers on gas pressure distribution are investigated. The results of parameter analyses using the presented model show that the assumption that homogenizations of gas generation rate and gas permeability through a landfill considerably overestimate gas pressure in landfill; horizontal permeable layer under final cover and horizontal gas collection layers can effectively reduce gas pressure in landfills; the bottom leachate drainage systems dually serving as gas collection layers can significantly reduce the gas pressure in the lower portion of landfills. The presented model provides a useful tool in the designing of landfill gas collection systems, such as, the positions and spacing of horizontal gas collection layers and pump section.