Systematic design of biodiesel and fatty alcohol production process

Abstract

Biodiesel is regarded as a promising alternative to a conventional petroleum-based diesel fuel. To reduce any risk for biodiesel producers, who rely only on the biodiesel product, the use of chemicals obtained from the biodiesel production to synthesize other high value-added products, such as fatty alcohol, has gained growing significance. The integration of fatty alcohol and biodiesel production results in a complicated process involving multi-components and various unit operations. The aim of this study is focused on the design and analysis of the production process of biodiesel integrated with fatty alcohol. The study is divided into four parts. In the first part, a systematic step by step methodology is developed for producing biodiesel and fatty alcohol products. A superstructure that includes all possible reaction and separation operations is generated through thermodynamic insights and available data. The number of alternative processes is systematically reduced through a screening procedure and economic analysis is performed to find the best economically and operationally feasible process. According to the methodology, a heterogeneous acid catalyzed process for biodiesel production integrated with fatty alcohol production is better than other process alternatives. In the second part, process intensification is applied to improve process performance in terms of productivity and energy consumption. A reactive distillation, which combines the reaction and separation tasks in the biodiesel production, is designed based on based on the element-based method. To further improve the performance of the reactive distillation in term of the energy consumption, a heat integration concept of the reactive distillation column is studied in the third part of the research. Various types of the heat-integrated reactive distillation are considered. Based on the minimization of a total annual cost, the multi-effect indirect split arrangement reactive distillation is the most attractive choice. In the final part of this study, the separation process of the fatty alcohol products is designed taking into account the total annual cost. The results indicate that the energy consumption of the fatty alcohol separation process can be minimized when the thermal coupling distillations are applied. In addition, the capital cost of the separation process is decreased because the number of unit operations, such as a condenser and a distillation column can be reduced.