Study On Landfill Gas Generation And Migration Model In Municipal Solid Waste Disposal Field In Changsha City

Landfill gas is generated by the degradation of waste in the landfill.The main component is methane and carbon dioxide,which a strong greenhouse effect gas.Uncontrolled emissions not only have a huge impact on the environment,but also endanger the health and safety of the surrounding residents.Dioxide can be used to generate electricity,with a high recovery value.It is necessary to carry out the landfill gas recovery and utilization project.Talk about the collection of landfill gas,the focus is on the prediction of gas production and the amount of collection.So the study of gas production and migration is the main point.This thesis based on the actual situation of municipal solid waste disposal field in Changsha city,analyzes the gas production model and compares the domestic gas production model and relevant parameters.Finally identified in line with the Changsha model.Also,the relationship between the final gas production L0 and the gas production rate constant K is analyzed,and the relationship between L0 and the waste component is obtained.Only in this way the gas production can be predicted.By comparing several landfill gas production models and gas production rate models,the Scholl-canyon model was used to estimate the gas production and gas production rate of landfill gas in Changsha solid waste landfill.Through the estimation,Changsha City landfill gas production peak for 2013~2053,the highest point in the gas production in 2028,gas production rate of 41454.34m~3/h.The average gas production rate for other years is 22952.26 m~3/h.In 2015,Changsha City Urban Management Bureau commissioned to predict the gas production of landfill,combined with the model to confirm the landfill operation to 2015 the average gas production rate of 6245.772m~3/h.The landfill gas production rate for 2015 is 14,051m~3/h.For the study of landfill gas migration model,this thesis establishes the theoretical model of gas migration and the related control equations when analyzing the migration rules of landfill gas,and obtains the solution method of the equations.According to the theoretical model and CFD software,the migration of landfill gas in landfill was numerically simulated.First of all,we simulate the shaft exhaust of Fresh Kills landfill in New York,and use the research results of Yen-Cho Chen to verify the correctness of the model and then simulate the solid waste disposal site in Changsha.Finally,we get the following conclusions:The pressure inside the landfill can be up to more than 650Pa without active pumping.By investigating the effect of different depths and different negative suction pressures on the interior of the landfill,it is found that the gas production of the gas gathering well increases with depth is proportional to the greater the negative pressure the greater the amount of gas collected,but when the negative pressure is too large cover and wellhead reflux will occur,making the air and landfill gas mixture.When the permeability coefficient anisotropy is used inside the landfill,the value of Kh/Kv changes from 3.0 to 30.0,and the pressure in the landfill increases gradually with the maximum pressure up to3842.3Pa.When the viscosity coefficient isotropic,the internal pressure up to669.8Pa and 283.39Pa.The results of this thesis can provide a reliable basis for the gas recovery in the Migration Model in Municipal Solid Waste Disposal Field in Changsha City,and provide reference for the application and management of landfills in other areas.