Numerical Modelling of Mass Recovery During Thermal Conductive Heating
Loading...
Authors
Xie, Qianli
Date
Type
thesis
Language
eng
Keyword
Modelling , In situ thermal treatment , Macroscopic invasion percolation , Non-aqueous phase liquids , Mass recovery , Co-boiling
Alternative Title
Abstract
The primary objective of this thesis was to develop a computationally efficient numerical model for simulating the mass recovery of volatile organic compounds (VOCs) from dense non-aqueous phase liquid (DNAPL) source zones by in situ thermal treatment (ISTT). The model was developed in three stages.
In the first stage, a one-dimensional (1D) radial model was developed to simulate conductive heat transport coupled with the vaporization of single and multi-component VOCs in laboratory ISTT treatability tests. This 1D model was validated against laboratory experiments and the calibrated model successfully predicted the measured temperature, DNAPL saturation, and DNAPL composition during heating.
In the second stage, the 1D model was extended to two dimensions and incorporated a macroscopic invasion percolation (macro-IP) approach to simulate the migration of vapours resulting from the vaporization of DNAPL. This two-dimensional (2D) model was used to examine the mass recovery from 60 realizations of DNAPL distributions under three levels of permeability heterogeneity. The results showed that mass recovery was not very sensitive to permeability heterogeneity. In addition, the heating time required for removing all the DNAPL was dictated by the DNAPL pools that were highly saturated, deep in the domain, and far from heaters.
In the third stage, the 2D model was extended to three dimensions and incorporated the condensation of vapours. This three-dimensional (3D) model was used to examine the effect of heater placements on mass recovery. Simulation results showed condensation outside the target treatment zone (TTZ) in all scenarios during heating; nevertheless, the scenarios with undersized TTZ had lower mass recovery than other scenarios. Moreover, the locations of unrecovered/condensed DNAPL could be inferred based on mass recovery tailing that occurred in certain monitoring wells.
The last manuscript chapter of the thesis investigated the effect of groundwater flow in heterogeneous permeability fields on low temperature thermal treatment (LTTT). An enhanced reaction zone of hydrolysis was determined using an average half-life considering the temperature history during and after heating. Results suggested that the enhanced reaction zone was located downstream of the heater zone due to groundwater flow and that the increase of permeability heterogeneity could result in a decrease in the extent of the enhanced reaction zone at a mean velocity of 0.3 m/day.
Description
Citation
Publisher
License
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-ShareAlike 3.0 United States
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-ShareAlike 3.0 United States