By Dr. José M del Valle and Gonzalo A. Núñez

Pontificia Universidad Católica de Chile and Universidad Técnica Federico Santa María, Chile

Friday May 15th, 2020 at 10:00 am Mexico City, MX (15:00 UTC)

Mathematical modeling of Super Critical (SC) CO₂ extraction of solid substrates usually relies on differential mass balances for thin sections of packed beds where most parameters are estimated from literature correlations, and where single unknowns are terms describing 1) solute partition between SC-CO₂ and the substrate, and 2) mass transfer within the solid substrate. A robust mathematical model of this type can be used to simulate industrial SC-CO₂ extraction plants to assess the techno-economic feasibility of industrial processes. Usual assumptions of mathematical models of SC-CO₂ extraction for solid substrates are 1) packing of single-size particles, 2) plug-type flow pattern of SC-CO₂, and 3) constant properties of SC-CO₂ in the extraction vessel. To an extent, these assumptions are fulfilled by carefully adjusting experimental conditions at the laboratory scale. This work assessed the effect of the particle size distribution, radial velocity gradients of CO₂, axial pressure gradients, and axial and radial temperature gradients on SC-CO₂ extraction of solid substrates in packed beds. Mathematical models were applied to simulate the extraction curves of the process under these “non-ideal” conditions. Some experiments confirmed selected simulated results and helped to identify situations that require corrections to reproduce industrial plants accurately. The justification for undertaking this research agenda is experimental evidence of “non-ideal” extractions at a large scale that includes radial gradients in extraction yield and extraction curves differing depending on the experimental scale. This presentation will examine the extent of selected non-idealities in extraction curves at different scales, and their potential effect on the mathematical simulation of industrial SC-CO₂ extraction processes.