Chemical Engineering Transactions (Jul 2022)
CFD Investigation of Industrial Gas-liquid Preneutralizer Based on a Bioreactor Benchmark for Spargers Optimization
Abstract
In this paper, a benchmark study between chemical and biochemical reactors is carried out using Computational Fluid Dynamics (CFD) approach. The main motivation is to develop an optimized design of a stirred sparged gas liquid reactor for preneutralisation of phosphoric acid. A CFD multiphase model is tailored under ANSYS Fluent 2020 R1, to simulate the industrial preneutralizer. A new gas sparger is designed based on fermentation bioreactors ring spargers for axial gas dispersion. The Euler-Euler multiphase reacting flow model is used within the preneutralizer to examinate the impact of the spargers type on the hydrodynamics, species transport phenomena, and mass transfer between the different phases. K-Epsilon turbulence model is adopted to integrate the turbulence due to the Pitch Blade Turbine (PBT) agitator, and Multiple Reference Frame (MRF) approach allows to handle efficiently the rotational movement of the agitator. The simulations show that ring spargers enhance mass transfer by ensuring a high level of gas phase holdup with the axial dispersion compared to the pipe spargers. The numerical results revealed that gas-liquid flow hydrodynamics is extremely sensitive to the sparger design. The proposed new preneutralizer design is promising to increase the preneutralisation yield and allows to avoid several monitoring challenges.