Simulation modeling of the phase behavior of palm oil‐supercritical carbon dioxide

Abstract

The phase behavior of crude palm oil (CPO) with supercritical CO 2 was successfully modeled in an Aspen Plus ® 10.2.1 commercial simulator (Aspen Technology Inc., Cambridge, MA) using the Redlich-Kwong-Aspen (RKA) equation of state thermodynamic model. The modeling procedure involved estimating pure component vapor pressures and critical properties and computing a regression of phase equilibrium behavior. The interaction parameters for the RKA model were obtained from the regression of experimental phase equilibrium data for a binary system of palm oil components-supercritical CO 2 available in the literature. The distribution coefficients and solubilities of palm oil components obtained from this simulation showed good agreement with experimental data obtained from the literature. The model provides an efficient and cost-effective alternative for the preliminary design and optimization of a supercritical fluid extraction process involving a complex CPO-supercritical CO 2 system.Over the years, supercritical fluid extraction (SFE) technology has developed rapidly and found applications in the commercial production of vegetable oils, including palm oil. Palm oil contains various components such as MG (<1%), DG (2-7%), TG (>90%), FFA (3-5%), phospholipids, pigmented compounds, and several nutritionally bioactive compounds (1). Minor components such as β-carotene and tocopherol are often degraded or lost during the bleaching and refining processes, which require high operating temperatures of up to 240°C. Selective supercritical CO 2 extraction of these highvalue but thermally unstable components from crude palm oil (CPO) has enabled operation at mild temperatures of less than 100°C. In addition, the inert solvent used can be easily separated and recovered, thereby leading to a pollution-free operation. All these advantages combine to make SFE of components in palm oil a desirable alternative to conventional processing methods such as chemical and physical refining.By correlating limited experimental data gained from literature using thermodynamic models, a general representation of the phase behavior of a system can be determined, thus making it possible to reduce experimental work. The equation of state has been shown to adequately represent the phase behavior of lipid-related components with supercritical CO 2 (2-5). It is anticipated that the equation of state also can model the phase equilibrium of a palm oil components-supercritical CO 2 system. However, a reliable phase equilibrium model is required in the analysis of the SFE process involving a palm oil-supercritical CO 2 system since the system comprises a highly dissimilar mixture of high M.W. TG and low M.W. supercritical CO 2 . In addition, such a model must be applicable over a wide range of temperatures and pressures to yield some accurate quantitative values of the mutual solubilities, compositions of coexisting phases, and distribution coefficients that are of fundamental importance in the design of a countercurrent SFE process. The steps involved in...

Development of Molecular Distillation Based Simulation and Optimization of Refined Palm Oil Process Based on Response Surface Methodology

“…Consequently, thermodynamic properties and vapor pressure or pure component parameters for Antoine equations are required, and must be established. The thermo-physical properties are introduced in the simulation in terms of physical properties such as boiling point (TB), critical temperature (TC), critical pressure (PC), acentric factor (ω) and liquid molar volume (Vl20) for each component, and can be seen in Table A1 in the Appendix, as accomplished by Lim et al [13]. Equation (2) refers to an extension of the Antoine equation from Lim et al's work, and its parameters are shown in Table 3.…”

“…where S is sum of the squared error, m is the number of experimental data point within the temperature range of 373 K-503 K, P calc i is the calculated vapour pressure obtained from Lim et al's work [13] using Equation (2) and P exp i is the expected vapour pressure in Equation (3) (as available in ASPEN HYSYS). The pure component parameters for modified Antoine equation (Equation (3)) and coefficient of determination (R 2 ) of each component are summarized in Table 4.…”

“…Table 3. Pure component parameters for Equation (2), reproduced with permission from [13]. Copyright Springer, 2003.…”

Phase equilibria of palm oil, palm kernel oil, and oleic acid+supercritical carbon dioxide and modeling using Peng–Robinson EOS

“…The model predictions were also compared to the experimental VLE data presented in other literatures [1,19,23,26,27,29,30]. In addition, the phase equilibrium data were correlated with relatively simple PR-EOS using Wong-Sandler mixing rule.…”

“…Reliable high-pressure vapor-liquid equilibrium (VLE) data over a wide range of pressures and temperatures, and development of simple thermodynamic models provide basic, necessary information for the process development and economic evaluation of the extraction and the fractionation processes. Although many single component VLE data and modeling works are presented in open literature [15][16][17][18][19][20][21][22], only few works concerning multicomponent VLE data and thermodynamic modeling have been published [23][24][25][26]. In addition, some of these works are suffered from limited phase equilibria data at narrow temperature or pressure range, and complexity and low applicability of thermodynamic models.…”