Effects of flue gas recirculation on the thermal performance of the gas remediation well

Gas thermal remediation (GTR) is a promising novel soil remediation technology. Many problems such as high energy consumption and unreasonable temperature distribution are still commonly found in the application of the gas remediation well. External flue gas recirculation (e-FGR) was applied to improve the thermal performance of the well. A 3D CFD model of the gas remediation well coupled with e-FGR was developed to analyze the heat transmission and combustion process. Four representative e-FGR ratios, 15 %, 30 %, 45 %, and 60 %, were selected to analyze the relationship between the e-FGR ratio and the well thermal performance. The results show that limited impact is obtained at a low e-FGR ratio and excellent results can only be achieved when the e-FGR ratio reaches 60 %. The maximum flame temperature was reduced by about 28 % at an e-FGR ratio of 60 % when compared with conventional combustion conditions. Localized high-temperature areas on the well surface are eliminated. The total heat transfer of the well increased from 4.69 kW to 6.16 kW when the e-FGR ratio increased from 0 to 60 %, which means a 23.9 % reduction in the remediation cycle and fuel consumption can be achieved at an e-FGR ratio of 60 %.