Modeling of PAH elimination by adiabatic steam stripping and intraparticle desorption

The decontamination process of solids loaded with PAH (e.g., naphthalene) in a pilot plant was modeled. This process was separated into two main stages: fast steam stripping at the entrance of the separation tube and the subsequent slow desorption of PAH from the interior of the soil particles. The stripping process occurred in two stages: fast diffusion controlled saturation of the partial pressures followed by the heat transfer controlled evaporation. The obtained results were contrasted with analytical data for systems exhibiting linear isotherms by dispersive approximation. When the heat of the introduced steam was insufficient for total evaporation of the liquid layer, the process stopped when the temperatures of the steam and droplet were in equilibrium. Radiative heat transfer was small at given temperature characteristics of the separation unit and of the size of droplets, which are < 1 mm. The saturation of pressures during steam stripping ends the same side of the phase diagram, with respect to the azeotropic fraction.