Desorption of Soil Contaminants During Steam Cleaning

蒸汽清洁过程中土壤污染物的解吸

• 批准号: 9115746
• 负责人: Massoud Kaviany
• 金额: $ 27.02万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-09-15 至 1994-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9115746&HistoricalAwards=false
• 关键词: Desorption; Soil; Contaminants; During; Steam

This study is an investigation of the fundamentals of heat and mass transfer occurring during the steam cleaning of contaminants adsorbed in soil. The heat transfer and the condensate and gas flow are analyzed assuming local thermal equilibrium, convection, dispersion, gravity, capillarity and diffuso- and thermo-capillarity. The mass transfer among the phases (solid, liquid, and gas) are analyzed based on local non-equilibrium assumptions. The interfacial mass transfer coefficients and the specific surface areas are obtained by a direct simulation of two-phase flow in a phenomenological unit-cell. Experiments are performed in soil columns using contaminant simulants with a controlled initial equilibrium (solid-gas) condition prior to injection of steam. Transient local temperature, capillary pressure, and contaminant concentration (in liquid and gaseous phases) measurements are made. The results of the experiments will be compared to those predicted in order to examine the validity of the phenomenological unit- cell based kinetic model. The proposed research will allow for the development and critical verification of the pore-level analysis of heat and mass transfer in soil during steam cleaning. For the first time, the local velocity and local saturation dependence of the mass transfer rates among the three phases will be determined by a direct simulation and will be verified experimentally. The results will also be valuable for analysis/prediction of the isothermal remediation processes.

本研究是对吸附在土壤中的污染物在蒸汽清洗过程中发生的热质传递的基本原理的研究。在假设局部热平衡、对流、弥散、重力、毛细、扩散和热毛细的假设下，对凝析油和气体的流动、换热和换热进行了分析。基于局部非平衡假设，分析了固、液、气三相之间的传质过程。通过对唯象单胞内两相流动的直接模拟，得到了界面传质系数和比表面积。实验是在注入蒸汽之前，在初始平衡(固-气)受控条件下使用污染物模拟物在土柱中进行的。进行了瞬时局部温度、毛细压力和污染物浓度(液体和气相)的测量。实验的结果将与预测的结果进行比较，以检验现象学单位的有效性-基于细胞的动力学模型。拟议的研究将允许开发和关键验证在蒸汽清洗过程中土壤中的热量和质量传输的孔隙级分析。首次通过直接模拟确定了三相传质速率的局部速度和局部饱和度依赖关系，并进行了实验验证。研究结果也将对等温修复过程的分析/预测有价值。