Smouldering Combustion as an Emerging Technology for Contaminated Site Clean-up: Computational Simulations

摘要

Smouldering, a flameless form of combustion is the governing process of an innovative environmental technology called Self-sustaining Treatment for Active Remediation (STAR). STAR involves the destruction of organic liquids in soil through self-sustained smouldering. A one-dimensional numerical model was developed to simulate the smouldering remediation of bitumen-contaminated sand. A one-step char oxidation mechanism was employed with Arrhenius parameters calculated from thermogravimetric experiments for bitumen under air. Local thermal equilibrium between sand and air was assumed and radial heat losses were considered. Model results were compared to a smouldering experiment using bitumen-contaminated sand. It was found that this simple model reasonably predicted the self-sustaining process: the peak temperatures, the smoul-dering front velocity, the complete destruction of bitumen, and the temperature decline due to heat losses behind the front. However, it failed to accurately predict the thickness of the front and heat transfer processes in the clean sand behind the reaction zone. This work suggests that more detailed chemical kinetic schemes and local thermal non-equilibrium processes may also be necessary to accurately simulate smouldering remediation of liquid hydrocarbons.