An algorithm for predicting the hydrodynamic and mass transfer parameters in agitated reactors

The algorithm was used to predict the effects of liquid viscosity and hydrogen mole fraction in the feed gas (H2 + N2) on the hydrodynamic and mass transfer parameters for the soybean oil hydrogenation process conducted in a large-scale gas-sparging agitated reactor (7000 kg soybean oil capacity). The predictions showed that increasing the liquid-phase viscosity, mimicking the evolution of the hydrogenation of soybean oil in a batch reactor, decreased ɛG and increased dS, resulting in a decrease of a. The decrease of the gas holdup with increasing the liquid-phase viscosity was related to the increase of gas bubble coalescence in the reactor. Increasing liquid-phase viscosity, however, decreased kL as well as kLa values for both H2 and N2 within the range H2 mole fraction (0-1) used. This kL behavior indicated that the effect of viscosity on kL is more significant than that of dS, since kL was reported to be proportional to dS. The predictions also showed that increasing the H2 mole fraction in the feed to the reactor decreased ɛG and increased dS, resulting in a decrease of a and an increase of kL as well as kLa for both H2 and N2 within the range of liquid-phase viscosity used (0.0023-0.0047 Pa s). The decrease of the gas holdup with increasing the H2 mole fraction in the feed gas was attributed to the decrease of the density (momentum) of the gas mixture. The increase of kL values with increasing the H2 mole fraction in the feed gas was related to the increase of dS. The predicted kLa values indicated that the mass transfer behavior in the large-scale gas-sparging reactor proposed for soybean oil hydrogenation was controlled by the mass transfer coefficient, kL. Also, under similar conditions, kLa values for H2 in soybean oil when using the gaseous mixture (H2 + N2) were lower than those obtained for H2 (as a single-component); and kL values for H2 were consistently greater than those of N2 within the ranges of the operating conditions used in the simulation.