Comparison Of The Mixing Performance Of A Stirred Reactor, An Airlift Reactor And A Static Mixer In Biodiesel Production

As the energy crisis and environment pollution become more serious, a great deal of attention is paid to biodiesel, which is biodegradable and renewable. Along with the rapidly growing consumption of biodiesel, the production of biodiesel on a large scale became a hot research point. Given the economic and environmental benefits, waste cooking oil is used as raw material. Due to the immiscible nature of oil and methanol, it is necessary to introduce an efficient mixing method to homogeneously disperse methanol into waste cooking oil in the enzyme-catalyzed transesterification. This study accesses the mixing performance of a stirred reactor, an airlift reactor and a static mixer in the biodiesel production in a tank of lm I.D and 1.5 m fluid height. Static mixer reactor shows a better performance than both stirred and airlift reactors in terms of methanol volume fraction and distribution. Methanol can be dispersed uniformly in the outlet, with a methanol volume fraction and average velocity of the oil phase of 0.2025 and 0.19 m/s, respectively. In the oil-water mixing experiment, the water dispersed to 1～3μm droplet after 2.5 min. In the biodiesel production experiment, it has been proven that using static mixer was able to shorten the reaction time to 7.5 h, compared with 24 h using stirred reactor. In terms of energy analysis, the results indicate that more than 50% of consumption can be saved in the reacting process.Based on above simulation, experiment validation and energy analysis, static mixer reactor shows a better performance in the biodiesel production.