A CFD model for predicting the flow patterns of viscous fluids in a bioreactor under various operating conditions

Abstract

Computational fluid dynamics simulation is becoming an increasingly useful tool in the analysis and design of simultaneous saccharification fermentation (SSF) and saccharification followed by fermentation process (SFF). To understand and improve mixing and mass transfer in a highly viscous non-Newtonian system, it was necessary to simulate the flow behavior in this bench scale bioreactor (BioFlo 3000). This study focused on designing a high concentration medium agitation system for such a process using the commercial computational fluid dynamics package Fluent (V. 6.2.20) and its preprocessor Mixsim (V. 2.1.10). The objective of this study is to compare performance of various designs of a bioreactor and identify the flow pattern and related phenomena in the bench scale tank. The configuration of the physical model for simulating a mixing tank with a Rushton impeller consists of an ellipsoidal cylindrical tank with four equally spaced wall mounted baffles extending the vessel bottom to the free surface, stirred by a centrally located six-blade Rushton turbine impeller. Simulations were performed with the original and a modified design in which the lower bottom shaft mounted a Lightnin A200 impeller. The results suggest that there is a potential for slow or stagnant flow between top impellers and bottom of the tank region, which could result in poor nitrogen and heat transfer for highly viscous fermentations. The results also show that the axial velocity was significantly improved for the modified geometry in the bottom of the tank.

A CFD simulation for the ultrasonic flow meter with a header

“…They found that when using nonhomogeneous and nonlinear pipe materials, the measurement error would depend on the acoustic characteristics of the pipe material [13]. In terms of simulation, Byunghad studied the completely velocity distribution of rotating and swirling turbulent flows in circular pipes by using computational fluid dynamics (CFD) simulation to investigate the effect of distorted flow profiles, especially the effect of out-ofplane double bent pipe on ultrasonic flow metering [14]. Luca et al simulated ultrasonic flow meter by modelling the wave propagation in solids with the equations of linear elasticity and the linearized Euler equations in fluids [15].…”

Optimization and Evaluation of Organic Acid Recovery from Kraft Black Liquor Using Liquid-Liquid Extraction

“…There are many different definitions of the word "biorefinery," but the term is generally applied to the use of renewable raw materials (e.g,, biomass) to produce energy, together with a wide range of everyday commodities, in an economic and sustainable manner [2][3][4][5]. The biorefinery concept applies the methods that have been used to refine petroleum to biomass conversion [3]. Biorefineries simultaneously produce biofuels, biobased chemicals, heat, and power.…”

Recovery of Acetic Acid from An Ethanol Fermentation Broth by Liquid-Liquid Extraction (LLE) Using Various Solvents

“…Acetic acid is a normal end-product of alcoholic fermentation in the biorefinery process, and can also be formed by Saccharomyces cerevisiae; additional amounts may be produced after alcoholic fermentation by lactic acid bacteria [2][3][4][5] and/or acetic acid bacteria [6]. The concentration of acetic acid produced during alcoholic fermentation may vary with the species of strains [7,8], the composition of hydrolysates [9], and other physical factors [10,11].…”