Simulation of a supercritical carbon dioxide extraction plant with three extraction vessels

Although SuperCritical (SC) Fluid Extraction (SCFE) has been successfully applied commercially the last three decades, there is no systematic procedure or computational tool in the literature to scale-up and optimize it. This work proposes an algorithm to simulate dynamics in a multi-vessel (≥3) high-pressure SCFE plant where extraction vessels operate in batches, and is thus forced to use simulated-countercurrent flow configuration to improve efficiency. The algorithm is applied to a three-vessel SCFE plant using a shrinking-core model to describe inner mass transfer in the substrate. As example, the extraction of oil from pre-pressed seeds using SC CO2 at 313 K and 30 MPa is simulated. After three cycles the process reaches a pseudo-steady-state condition that simplifies the estimation of plant productivity. Use of a three- instead of two-vessel SCFE plant increases oil concentration in the stream exiting the plant and decreases CO2 usage at the expense of increasing extraction time.

► New algorithm to simulate a supercritical fluid extraction industrial plant. ► Mass transfer in a supercritical fluid extraction plant with three or more vessels. ► Supercritical CO2 extraction of pre-pressed rapeseeds at 40 °C and 30 MPa. ► After three cycles the extraction process reaches a pseudo-steady-state condition. ► The use of three instead of two extraction vessel saves CO2 usage in the plant.