PCB Migration and Cleanup Scenarios in Natural Gas Pipelines

A model for tracking PCB migration under a variety of solvent injection scenarios is presented. The model serves as a tool for evaluating the efficacy and efficiency of solvents as a means of decontaminating PCB-contaminated natural gas pipelines. The model accounts for the continuous mass transfer between the pipe wall and the multiphase fluids flowing in the pipeline. Consideration is given to the processes of PCB desorption from the pipe wall, and the possibility of subsequent re-adsorption to the pipe wall. To capture the multiple mechanisms involved adequate coupling of hydrodynamic, thermodynamic, and mass transfer modeling is called for and used in this study. The study shows that PCBs concentrate in the liquid phase which is the primary transport phase. It also demonstrates that the model could be used to design an optimal pipeline decontamination scenario.