Analysis of methanol recovery using component specific reaction kinetics in biodiesel synthesis

ABSTRACT

Transesterification is the process of transmutation of fatty acids to alkyl esters (biodiesel) when reacted with alcohols such as methanol, ethanol, etc. The unreacted methanol in the process downstream can be recovered and reused economically by integrating methanol recovery with transesterification, thereby mitigating the environmental and health hazards caused by direct release of the same. The present work deals with the simulation of methanol recovery integrated transesterification of poppy seed oil in ASPEN Plus process simulator. The transesterification process is simulated using a component-specific kinetic model by considering four constituent triglycerides of poppy seed oil, namely, oleic acid, palmitic acid, linoleic acid, and stearic acid. The model is made more comprehensive by incorporating six-step reaction mechanism for each triglyceride to simulate its respective alkyl ester conversion. Recovery of excess methanol is implemented using a distillation-based methanol recovery unit. The prediction accuracy of the model is found to be 3.51% when the model predicted biodiesel yield is compared with the corresponding experimental values. The validated model is used to analyze the effect of methanol-to-oil ratio, reboiler duty, temperature, pressure and reflux ratio on methanol recovery. From the analysis, it is found that a methanol-to-oil ratio of 6:1 and process temperature of 60°C corresponds to maximum biodiesel yield. For the maximum yield condition, a maximum methanol recovery of 0.945 can be attained economically at a reboiler duty of 500 cal/s and reflux ratio 2.

KEYWORDS:

• Poppy seed oil
• biodiesel
• methanol recovery
• ASPEN Plus

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Christy Thomas Sani

Christy Thomas Sani is a Chemical Engineering graduate from the National Institute of Technology Calicut, Kerala, India. His research interest includes fuel cell technology and biodiesel synthesis. During his undergraduate studies, he developed a fuel cell-powered hybrid car in MATLAB SIMULINK. He has two international publications in the area of biodiesel in his credit.

Rupesh S

Dr. Rupesh S completed Master of Technology in Propulsion Engineering from College of Engineering Trivandrum, Kerala, India, in 2010. He secured Ph.D in Biomass Gasification from National Institute of Technology Calicut in 2017. His areas of research include Thermochemical Gasification, Transesterification, Anaerobic Digestion and Buoyancy driven flows. He has published 10 peer reviewed International journals, 18 International conferences and one book chapter in the area of Biofuels. He served as the reviewer for 11 peer reviewed International journals published by various renowned publishers and also as technical session chair of various International conferences. Currently, he is working as Assistant Professor in the Department of Mechanical Engineering, PES College of Engineering, Mandya, Karnataka. Presently he is also the district coordinator of Biofuel Research Information and Demonstration Centre, sponsored by Karnataka Bioenergy Development Board (KSBDB) Bangalore.

Chris Ben Xavier

Chris Ben Xavier is a Chemical Engineering graduate from the National Institute of Technology Calicut, Kerala, India. His research interest includes biodiesel synthesis, green hydrogen production and storage, fuel cell and so on. He has modelled a fuel cell-powered hybrid car in MATLAB SIMULINK software during his undergraduate studies. Currently he is working in the development of a decoupled water splitting electrolyser for hydrogen production.

Rag R L

Dr. Rag R L secured his Ph.D from National Institute of Technology Calicut, Kerala, India in the area of computational heat transfer in 2010. His graduation and post-graduation were from TKM College of Engineering, Kollam, India in 1999 and 2002, respectively. He has six International journal publications and two International conference publications in the area of electronics cooling and computational heat transfer. He is the reviewer of two international peer review journals. A book titled “Introduction to Sustainable Engineering” was authored by him. He is having a teaching experience of more than twenty years. Dr. Rag R L served as resource person for faculty development programmes in the area of computational heat transfer. Currently he is working as the Professor and Head in the Department of Mechanical Engineering at SCMS School of Engineering and Technology, Cochin, Kerala, India.