Simulation, optimization, and economic analysis of process to obtain esters from fatty acids

Abstract

Waste oils are a very promising raw material in the biodiesel industry, which is why great efforts have focused on the removal of the free fatty acids (FFAs) present in this source, mainly through the esterification reaction. Many studies have evaluated the influence of different variables on the reaction conversion, such as temperature, catalyst concentration, and alcohol/oil ratio. However, it is still necessary to verify how the esterification is affected by higher water concentration. In this study, different acid‐catalyzed esterification reaction conditions with distinct water concentrations were tested experimentally, and a new rate expression was proposed. This newly obtained reaction kinetics was then used to undertake a complete analysis of the biodiesel production process from waste oil, evaluating the influence of higher water concentrations in the esterification, and including different optimizations and an economic evaluation. Concerning some of the process modifications, it was verified that the inclusion of three energy‐saving heat exchangers reduced utility costs by 40%. In contrast, the inclusion of an ethanol‐recycling distillation column reduced raw material costs by 40%. Different settings were also tested, varying the feed composition and the esterification reaction time and conditions, resulting in a payback period of less than 3 years in any evaluated scenario. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Investigating the high‐shear mixed catalytic esterification of lauric acid with methanol using central composite design

“…In this way, it is proved that the model has the capacity to reproduce the responses since the maximum conversion value was close to the experimental one. Notice that this LA conversion value is at the level of counterparts reported in the literature based on the information in Table 1 comprising not only homogeneous but also heterogeneous and enzymatic processes 5‐23 . More importantly, the maximum LA conversion in our work was attained at a comparatively milder severity in terms of time (12 min vs 1‐24 h).…”

“…For homogeneous processes, for instance, almost full conversion of LA when reacting with methanol was reached using sulfate compounds as catalysts requiring from 1 to 3 h of reaction time 18‐20 . In the LA esterification with ethanol catalyzed with sulfuric acid, ~88% LA conversion was attained after 1.7 to 2 h of operation 23‐25 . This implies that, attractively, the HSM‐assisted esterification can be envisaged as a simplified and less energy consumption process option.…”

“…[18][19][20] In the LA esterification with ethanol catalyzed with sulfuric acid, $88% LA conversion was attained after 1.7 to 2 h of operation. [23][24][25] This implies that, attractively, the HSM-assisted esterification can be envisaged as a simplified and less energy consumption process option. Noteworthily, the slight positive effect and nonstatistically significance of the mixing speed on LA conversion would indicate that the HSM-assisted acid esterification of LA with methanol to ML may be run at mild conditions of mixing speed without penalty in the efficiency of the reaction.…”

“…Notice that this LA conversion value is at the level of counterparts reported in the literature based on the information in Table 1 comprising not only homogeneous but also heterogeneous and enzymatic processes. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] More importantly, the maximum LA conversion in our work was attained at a comparatively milder severity in terms of time (12 min vs 1-24 h). For homogeneous T A B L E 8 Quantification of linear and quadratic effects as well as binary interactions with confidence intervals at the 95% probability level for reduced regression model representing the five-factor CCD applied to investigate the HSM-assisted acid esterification of LA with methanol to ML The number 2.030 was taken from the t-test tables at the 95% probability (α = 0.05) and the degrees of freedom of the total error (=36), vide Table 7.…”

Reactive Distillation Applied to Biodiesel Production by Esterification: Simulation Studies

“…The compounds defined for the simulation of the fatty acid esterification with ethanol were specified in the Aspen Plus V.12 process simulator, with the fatty acid and oil fraction represented by oleic acid and triolein, respectively. A similar approach was used by other researchers as a simplification of the numerous components of the acid and oil fraction of the feedstock [58][59][60]. The NRTL thermodynamic model [61] was selected to evaluate the activity coefficients of the components of the reaction mixture and the NRTL binary interaction parameters missing from the simulator database were estimated directly through the Aspen Plus estimation tool that uses the UNIFAC model [62].…”