Simulation of a flexible multi-vessel extraction plant with counter-current contacting between a solid substrate and supercritical CO2

Abstract

This work develops a program (MVSEPS) to simulate a multi-vessel SuperCritical Fluid Extraction (SCFE) plant operating in a counter-current fashion. MVSEPS was applied to an SCFE to extract hemp seed oil using the shrinking core mass transfer model. A microstructural factor was best-fitted to experimental data from literature, to describe the inner mass transfer of the oil within the substrate, that was used as a parameter in subsequent simulations. The oil concentration in the CO2 stream exiting an extraction vessel, and the productivity, and efficiency of the SCFE plant were studied by changing selected parameters of the process and extraction conditions. The number of extraction vessels operating in series and the cycle time were relevant simulation parameters, because they cannot be studied experimentally at a laboratory scale. Using a larger number of extraction vessels and shorter cycle times increase the plant productivity but decrease the extraction efficiency. Other parameters studied, such as the particle size of the milled substrate, superficial CO2 velocity, extraction temperature and pressure, impact the operation of the SCFE plant similarly to at laboratory scales.