Xie Qianli, Mumford Kevin G, Kueper Bernard H
Queen's University, Department of Civil Engineering, Kingston, Ontario K7L 3N6, Canada.
Queen's University, Department of Civil Engineering, Kingston, Ontario K7L 3N6, Canada.
J Hazard Mater. 2023 Jul 5;453:131439. doi: 10.1016/j.jhazmat.2023.131439. Epub 2023 Apr 17.
Thermal conductive heating (TCH) is an in-situ thermal treatment (ISTT) technology for treating non-aqueous phase liquid (NAPL) source zones. Numerical models can be useful tools for improving remedial performance, but traditional multiphase flow models are rarely used to simulate mass recovery during ISTT applications at the field scale due to their computational expense. This study developed a 3D model based on macroscopic invasion percolation to simulate the vaporization of NAPL, and the subsequent vapor migration and potential condensation at the field scale. The model was used to simulate the mass recovery of trichloroethene (TCE) from a NAPL source zone under seven scenarios of different heater placements, including three scenarios with an undersized target treatment zone (TTZ). Simulation results showed that TCH was effective in removing NAPL within the TTZ, but the treatment zone did not extend far from the perimeter heaters. In addition, during heating, NAPL condensation outside the TTZ due to the escaping vapor was observed in all scenarios. Overall, the resulting mass recovery was lower in the three scenarios with an undersized TTZ (91-95%) than in the other four scenarios (≈ 99%). Moreover, the locations of unrecovered/condensed NAPL could be inferred by monitoring mass recovery tailing at individual extraction wells.
导热加热（TCH）是一种用于处理非水相液体（NAPL）源区的原位热处理（ISTT）技术。数值模型可能是提高修复性能的有用工具，但传统的多相流模型由于计算成本高，很少用于模拟现场规模的ISTT应用过程中的质量回收情况。本研究基于宏观侵入渗流开发了一个三维模型，以模拟NAPL的汽化，以及随后在现场规模的蒸汽迁移和潜在冷凝。该模型用于模拟在七种不同加热器布置场景下，从NAPL源区回收三氯乙烯（TCE）的质量，其中包括三种目标处理区（TTZ）尺寸过小的场景。模拟结果表明，TCH在去除TTZ内的NAPL方面是有效的，但处理区并没有延伸到远离周边加热器的地方。此外，在所有场景中都观察到，在加热过程中，由于逸出的蒸汽，TTZ外出现了NAPL冷凝现象。总体而言，在三种TTZ尺寸过小的场景中，最终的质量回收率（91 - 95%）低于其他四种场景（约99%）。此外，通过监测各个抽提井的质量回收拖尾情况，可以推断未回收/冷凝的NAPL的位置。
