Interface Mass Transfer in Reactive Bubbly Flow: A Rigorous Phase Equilibrium-Based Approach

S B Øyen,T Haug-Warberg,J Solsvik,H A Jakobsen

doi:10.1021/acs.iecr.1c03131

Abstract

In this work, the driving force of interfacial mass transfer is modeled as deviation from the gas–liquid equilibrium, which by assumption is thought to exist at the interface separating the gas and liquid phases. The proposed mass transfer model provides a flexible framework where the phase equilibrium description in the driving force can be substituted without difficulties, allowing the mass transfer modeling of distillation, absorption/stripping, extraction, evaporation, and condensation to be based on a thermodynamically consistent phase equilibrium formulation. Phase equilibrium by the Soave–Redlich–Kwong equation of state (SRK-EoS) is in this work compared to the results of the classical Henry’s law approach. The new model formulation can predict mass transfer of the solvent, which Henry’s law cannot. The mass transfer models were evaluated by simulating a single-cell protein process operated in a bubble column bioreactor, and the solubilities computed from the SRK-EoS and Henry’s law were in qualitative agreement, albeit in quantitative disagreement. At the reactor inlet, the solubility of O2 and CH4 was 150% higher with the SRK-EoS than with Henry’s law. Furthermore, the SRK-EoS was computationally more expensive and spent 10% more time than Henry’s law.

Highlights

Mass transfer is crucial in many chemical engineering applications
A novel mass transfer model based on thermodynamic phase equilibrium at the gas−liquid interface was derived for the bubble column in the section Mass Transfer
The second part, Nonreactive System: Three Components, presents the results of a simplified test case of mass transfer in a ternary mixture without reaction to verify that the novel mass transfer model described in the section Rigorous Phase Equilibrium: Consistent Fluxes yields physical results

Summary

Introduction

Mass transfer is crucial in many chemical engineering applications. For instance, mathematical modeling of separation processes such as distillation, absorption/stripping, extraction, evaporation, and condensation depends on a physical description of mass transfer between a liquid and a gas phase.In biochemical engineering, on the other hand, bacteria rely on substrates and possibly O2 to sustain their metabolism. Mass transfer is crucial in many chemical engineering applications. Mathematical modeling of separation processes such as distillation, absorption/stripping, extraction, evaporation, and condensation depends on a physical description of mass transfer between a liquid and a gas phase. On the other hand, bacteria rely on substrates and possibly O2 to sustain their metabolism. A particular bacterium, Methylococcus capsulatus (Bath), is an aerobic, methanotrophic bacterium that has received much attention due to its high protein content (≈70− 80% on a dry mass basis, see, e.g., Olsen et al.,[1] Øverland et al.,[2] and Anupama and Ravindra[3]). M. capsulatus (Bath) consumes CH4 and O2 to grow.[7] Both CH4 and O2 are highly volatile compounds, and they are conveniently supplied to the broth from a gaseous phase

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Results

Conclusion