Prediction of volumetric data in supercritical reactors

Abstract

Pressure intensified processes are characterized by handling mixtures whose density is highly dependent on the operating conditions. In addition, fluid behavior in this type of equipment is clearly non-ideal. Therefore, the frequent assumption of ideal mixing for calculating the mixture density is inaccurate. Prediction of volumetric information of mixtures is important for the design of continuous supercritical reactors and other process equipments such as heat exchangers, high-pressure pumps, compressors, etc. The isochoric method is a simple and reliable procedure to measure mixture densities and find conditions of homogeneous operation of supercritical chemical reactor at high temperature and pressure. Moreover, it also provides PvT properties simultaneously.It is well known that the two-parameter equations of state (2P-EoS), like Soave-Redlich-Kwong or Peng-Robinson, have limitations to describe accurately the PvT properties of different fluids together with the phase transitions. The three-parameter RK-PR equation of state (3P-EoS), known as the generalized Redlich-Kwong-Peng-Robinson is able to correlate and predict volumetric properties of size-asymmetric mixtures. In this work, RK-PR, coupled with the standard quadratic mixing rules, is used to model volumetric experimental data of non-reacting size-asymmetric binary systems. Moreover, based on that modeling, we predict volumetric properties of reacting mixtures in the context of supercritical biodiesel production.