Produção de biodiesel sob condições supercríticas utilizando o destilado de desodorização do óleo de soja (DDOS)

Abstract

In recent decades, there has been a growing concern about the future of fossil fuels due to the environmental impacts they cause and the possibility of scarcity. Thus, alternatives are sought for the same purpose. In this context, biodiesel, a mixture of fatty acid esters, has become a viable alternative to replace diesel. However, conventional routes for biodiesel production typically use bases or acids that result in increased waste generation at the end of the process, in addition to producing a byproduct (glycerin) with lower added value. Therefore, alternative routes using agro-industrial residues in conjunction with supercritical fluids appear as promising solutions to the mentioned problems. In this regard, this project aims to use an agro-industrial residue, soybean oil deodorization distillate (SODD), in conjunction with methyl acetate under supercritical conditions for biodiesel production. In addition to biodiesel, sterols, tocopherols, acetic acid, and triacetin are produced as secondary products, with higher added value compared to glycerin. Market analysis revealed that the city of Ijuí (RS) has two soybean oil processing industries, making SODD available as their waste. Thus, the industrial unit is implemented in this city. After analyzing and synthesizing the process, the industrial unit consists of four areas: receiving, storing, and mixing raw materials; processes; storage and distribution of products; and utilities. From the calculations, 975.0 kg/h of biodiesel, 125.6 kg/h of acetic acid, 93.6 kg/h of triacetin, and 443.5 kg/h of a mixture of sterols, tocopherols, and triglycerides are produced, along with a residue of saponified products with 109.6 kg/h. After the primary mass and energy balance calculations, utility stream calculations were performed, where, in addition to the recirculating thermal oil, 821 kg/h of liquefied petroleum gas (LPG) and 0.27 m3/h of water are used, with reduced flow due to the use of the cooling tower to enable water reuse. Furthermore, with the implementation of process energy integration, a savings of 1,314,525 R$/year was achieved through the recycling of thermal oil used as the hot fluid in heat exchangers. Additionally, control was implemented for three equipment systems: mixer M-201, distillation columns, and for the reactor (R-201) and heat exchanger (E-201) assembly. Finally, for evaluating the viability of the process, an economical analysis was done. From this, the total cost obtained was 584,299,27 R$/year, a revenue of 127,485,021 R$/year, a total investment of 149,457,468 R$/year with a gross profit of 690,550,94 R$/year and, with that, a payback period of 7 years was achieved.