Calculation of phase equilibria and their relation to separation with supercritical fluids
Supercritical fluids are a unique class of solvents because solvent power is adaptable by changing pressure and temperature, or density. To make use of this feature, P,v,T- and phase equilibrium-behavior must be known. The best way is by calculation. Tools are available, most of them derived from cubic equations of state. These tools are applicable to fluid mixtures with components of very different volatility, such as supercritical fluids and low volatile compounds. Multi-component mixtures are modeled by combination of binary systems. In processes, process fluids occur at very different conditions. Cubic equations of state are successfully used to calculate P,v,T-behavior and composition of the process fluids for all different conditions. Furthermore, thermodynamic functions, such as enthalpy and entropy, are an intrinsic result of phase equilibrium modeling. A useful calculation package can be freely downloaded from: PE 2000 http://www.tuhh.de/v8/links-downloads/pe-2000/download.html.