Scale‐up and economic analysis for the design of supercritical fluid extraction equipment for remediation of soil

摘要

AbstractThe magnitude of the contaminated site clean‐up in the United States indicates the need for more effective, less costly remediation technologies. Supercritical Fluid Extraction (SFE) using carbon dioxide (CO2) as a supercritical fluid is a possible alternative technology for remediation of soils contaminated with volatile organic compounds. The feasibility of this process is mainly dependent on two factors: the extent and extraction rate of heavy molecular weight organic compounds from soil by supercritical carbon dioxide (SC‐CO2). This paper presents results of a bench‐scale study for remediation of soils contaminated with naphthalene and 1,2,4 trimethyl benzene as a function of the flow rate (Qco2) and supercritical fluid density (ρ co2). These data are used to perform a basic economic analysis of the process by using these two organics selected as model soil contaminants.An additional aim of this study was to develop scale‐up methodology from laboratory SFE devices to industrially useful equipment. Laboratory scale data, such as mass transfer coefficients, have implications for the sizing and control of process units including reactors and separation columns since high mass transfer rates allow smaller reactors. Furthermore, this study included the collection and analysis of the experimental data to support the application of the supercritical fluid extraction technology and to provide the conceptual design and operational processes required for the construction of a pilot plant unit.The experimental data were presented as an outlet concentration profile of solute (naphthalene or 1,2,4 trimethyl benzene) desorption at different flow rates. This qualitative analysis of the desorption experiments suggested that a promising model should include external and intraparticle mass transfer and be based upon equilibrium at a desorption site. Thus, a simulation has been performed using an equilibrium desorption model [1] and fitted using MATHEMATICA® software (version 2.2.2). Finally, a preliminary economic analysis using these results showed that the proposed process (SFE) is feasible for soils contaminated with two different pure (naphthalene or 1,2,4 trimethyl benzene) hazardous organics as a mod