Physico-chemical data required for the design of near-critical fluid extraction process

Abstract

Before the chemical engineering design of a proposed process can be initiated, values (or good estimates) will be required for a number of physico-chemical properties both for the pure components (these are usually comparatively easy to find) and the relevant mixtures. Extraction processes involving near-critical solvents are no more and no less demanding than other, more conventional, processes in this respect. Figures 1.16, 1.17 and 1.18, for example, and also 9.2 and 9.3 show simplified layouts for possible processes for extracting beds of solids or liquid streams with a near-critical solvent. In these cases the disengagement of the solute from the solvent gas is achieved by a throttling expansion. When carrying out the chemical engineering design of simple processes of this type, phase equilibria will be required for mixtures of the near-critical solvent with the material in the extractors and also for the solvent/solute mixtures in the separator. Mass transfer rate data will be required for sizing the continuous extractors in Figure 1.18 and 9.2. They will also be required in evaluating the performance of the extractor units (V1, V2, V3 in Figure 10.2 or 5 in Figure 9.3) used in the batch extraction of beds of solids.