Kinetics and control of palm fatty acid distillate esterification for a feasible biodiesel production

Abstract

The objective is to design the control structures for a smooth biodiesel production from palm fatty acid distillate. The kinetics of continuous esterification was investigated by considering the following operating parameters: reaction temperature in range of 50-70 °C and retention time in range of 10-30 min at a molar ratio of palm fatty acid distillate to methanol of 1:8. The experimental results gave the kinetic model as the pseudo-first order in free fatty acid for forward reaction and the second order in fatty acid methyl ester and water for backward reaction. The design and control of this process were studied also. Conventional and on-demand control structures with tray temperature control instead of composition control were proposed. Results showed that both proposed structures could handle changing in the process, ±10% of feed rate change, ±10°C of reactor temperature change, and 92-98% free fatty acid content with a satisfiable dynamic performance.

Keywords

• biodiesel
• esterification
• kinetics
• aspen plus
• process control