Two-Scale Model for Kinetics, Design, and Scale-Up of Biodiesel Production

Abstract

Optimization of biodiesel production requires fundamentals-based kinetic and reactor models. A liquid–liquid reactor requires reaction rate model including mass-transfer effects. Earlier studies have not analyzed such an effect in detail and thus cannot be used for scale-up and design. This work develops a two-scale model for design and scale-up. The intrinsic rate constant, fit from experimental data, is approximately 300 times larger than the apparent one. The model results for microchannel and stirred-batch reactors agree well with the experimental data and indicate that the former requires approximately 720 times shorter residence time than the latter. Scaling-up of an agitated-batch reactor to industrial scale by keeping tip speed constant provides lower performance due to inadequate power. In contrast, scaling-up with constant power/volume provides higher performance due to oversupply power. The two-scale model is used to adjust agitation speed for achieving performance similarity during scale-up. The corresponding power lies in between the two above-mentioned values.

Biodiesel Production by Heterogeneous Catalysis and Eco‐friendly Routes

“…Compared with conventional industrial plants, microchannel reactors have several advantages, such as shorter residence times, higher heat and mass transfer, and easier management, maintenance and operational control [23]. Mass transfer tends to be 30 times higher than on traditional scales [23].…”

“…Compared with conventional industrial plants, microchannel reactors have several advantages, such as shorter residence times, higher heat and mass transfer, and easier management, maintenance and operational control [23]. Mass transfer tends to be 30 times higher than on traditional scales [23]. Moreover, the better physical and energetic homogeneity increases the process viability without mass and heat spots that can damage the processing system.…”

“…The implementation of microscale plants offers an attractive alternative to traditional batch operations. Microplants naturally require smaller amounts of catalyst, enable shorter residence times, and provide higher heat and mass transfer, easier management, maintenance, and operational control [23]. Scale-up is typically achieved by serial or parallel operation of several microdevices [24][25][26].…”

Kinetics, Mass Transfer, and Reactor Scaling Up in Production of Direct Dimethyl Ether

“…The two-phase model, which is a function of a bubble size, can be used to find the appropriate bubble size. Bannatham et al 39 applied a similar concept to scaling up by controlling the size of the dispersed phase to maintain the same reactor performance in all scales. They applied a reactor model based on mass transfer phenomena to maintain performance when scaling up a stirred tank reactor running a two-phase reaction.…”