Coupling of hydrodynamics and chemical reaction in gas-lift reactors

A model was developed to study the strong coupling between hydrodynamics an d chemical reaction that occurs in external-loop gas-lift reactors. The mod el predicts the liquid circulation rate, as well as the axial profiles of g as holdup, pressure, gas and liquid velocity, and reactant conversion in th e riser. The study on the first-order, irreversible, isothermal reaction in the gas phase nA (k) over right arrow B with a change in the number of mol es on reaction shows that for n > 1, the gas holdup decreases along the ris er, the liquid circulation rate is lower than that in the absence of reacti on, and liquid circulation decreases as n and k increase. The bubble radius at the sparger and the inlet gas composition can have important effects on reactor performance. Scale-up strategies that involve increasing the react or length result in higher reactant conversion, but a lower ratio of liquid circulation rate to gas feed rate.