Design and control of biodiesel production processes with phase split and recycle in the reactor system

This work explores the design and control of a biodiesel production process with phase separation and internal recycle in the reactor system. Triglyceride reacts with methanol to form methyl esters and glycerol. Because the reactor effluent will separate into two liquid phases, the process can be improved by installing a decanter after each reactor and recycling the methanol-rich glycerol phase directly back to the reactor. We show that a 20% reduction in the total annual cost and a 26% reduction in energy cost can be achieved using this configuration. Finally, the plantwide operability and control of the entire biodiesel production plant with internal recycle are evaluated. The results indicate that the proposed process can handle 20% production rate changes with reasonable dynamic performance (a settling time of less than 10 h).