Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article Influenceofestimatedphysicalconstantsandvaporpressureforestersinthe methanol/ethanol recovery column for biodiesel production Hugo A.D. Medeiros a , Osvaldo Chiavone-Filho b ,RafaelB.Rios a, ⁎ a Departamento de Engenharia e Tecnologia, Universidade Federal Rural do Semi-Árido (UFERSA), 59625-900 Mossoró-RN, Brazil b Departamento de Engenharia Química, Universidade Federal do Rio Grande do Norte (UFRN), 59072-970 Natal-RN, Brazil ARTICLEINFO Keywords: Vapor pressure Physical constants Properties estimation Biodiesel Aspen Hysys ABSTRACT The influence of the estimated values of the physical constants and vapor pressure of esters in a process si- mulation using the Aspen Hysys was evaluated from the energy parameters of a methanol/ethanol recovery distillationcolumnofabiodieselproductionplant.Thisstudywasnecessary,becauseinprocesssimulatorsmost ofFAMEsandFAEEsarenotoriginallyavailableinthesimulatorlibrary,duetothelackofexperimentaldatafor these components. Accuracy analyses for the values of reboiler temperature and reboiler heat duty of the si- mulated column were performed from simulations using different predictive models and experimental data. Resultsdemonstratedthatsmalldeviationsofthevaporpressurecangenerateconsiderableerrorsinthereboiler temperatureandreboilerheatduty.Inaddition,errorscanbeevengreaterifvaporpressureisestimatedfrom inaccuratecriticalconstants.Deviationsupto13%wereobservedforthereboilertemperatureandupto16%for thereboilerheatduty.Itisdemonstratedthatreliablesimulationsandprocessdesignarestronglydependenton the selected physical properties of the esters, specially vapor pressure, which are generated from available experimental data and using group contribution and corresponding states models. 1. Introduction Currently, the use of biofuels has received increasing attention, mainly biodiesel use, that provides an alternative to replace fuels de- rived from petroleum or as a blending component of conventional dieselinvehicleengines [1].Biodieselisabiodegradableandnon-toxic fuel and presents better gas emissions [2,3]. This fuel is defined as a mixture of fatty acid alkyl esters (FAAEs) usually obtained by transes- terificationreactionbetweentriglycerides(vegetableoiloranimalfat) andshort-chainalcohol(primarilymethanolorethanol)inpresenceof alkali-catalysts [1,4,5]. Moreover,thebiodieselproducedfrommethanolorethanolresults in fatty acid methyl esters (FAMEs) or fatty acid ethyl esters (FAEEs), respectively [4]. General studies on FAMEs are most commonly found because of the low price of methanol [4]. Nonetheless, there is a growinginterestintheuseofFAEEsinbiodiesel [6],sinceitpresentsa higher cetane number and energy content, reflecting a better burning and lower fuel consumption [7–9]. Inordertoincreasethefeasibilityofbiodieselproduction,different homogeneous catalysts were evaluated [10–14], as well as hetero- geneous [15–19]. Some authors have reported that the use of solid catalysts returns high reaction rates and can even be easily removed after the reaction [17,20,21], resulting advantages such as the exclu- sion of purification steps, and consequently, the reduction in the number of equipment units in the process [21,22]. Moreover, config- urationsusingsupercriticalmethanolhavealsogainedprominencedue tohigherreactionratewithouttheuseofcatalyst,leadingtoaprocess intensification by the decrease of the separation step [5,23,24]. Given the difficulty of evaluating economically a biodiesel produc- tion plant from these different routes, process simulation has been presentedasanalternativetool.ThesesimulationsmustincludeFAMEs or FAEEs species, which usually are not available in the simulator li- brary, due to the lack of physical constants and vapor pressure data. Thisoccursmainlyduetothedifficultyinobtainingtheseestersinpure formsandincarryingouttheexperiments,becausethesesubstancesare thermal sensible for degradation at severe conditions, especially near their critical points [25]. Many studies may be found evaluating the economic viability of biodiesel production plants from process simulations [21,26–28] or have studied only biodiesel production through these simulators [22,29,30]. However, none of these studies focused in evaluating whether the thermodynamic model used is suitable for the mixture of interest(triglyceride+alcohol+biodiesel+glycerin).Furthermore, literature reports have not evaluated the ability of the available https://doi.org/10.1016/j.fuel.2020.118040 Received6March2020;Receivedinrevisedform5May2020;Accepted6May2020 ⁎ Corresponding author. E-mail address: rafael.rios@ufersa.edu.br (R.B. Rios). Fuel 276 (2020) 118040 0016-2361/ © 2020 Elsevier Ltd. All rights reserved. T