HYDRODYNAMICS, MASS TRANSFER AND SCALE-UP OF FISCHER-TROSPCH SLURRY PROCESS
Juan R. Inga
Air Products & Chemicals Inc.
Monday, November 23, 1998 3:30 pm
Ben Bandy Conference Center
Center for Applied Energy Research
Hydrodynamic and mass transfer characteristics were investigated in a 0.3 m diameter column. The 2 m tall column operated in the churn-turbulent regime with gas velocities reaching 0.25 m/s, catalyst concentrations up to 50 wt. % and up to 8 bars pressure. H2, CO, N2 and CH4 were used to determine the effect of gas density as well of gas type. The effect of pressure, gas velocity and catalyst concentration on gas holdup, bubble size distribution, coalescence and kLa were evaluated.
Using these results, a new scale-up/scale-down methodology for slurry bed reactors is proposed based on the rate limiting step of the overall process. The rate limiting step in slurry bed reactors, were one of the reactants is supplied in gas phase, is often the reaction kinetics or the gas/liquid mass transfer. The identification of the rate limiting step requires the assessment of the gas/liquid mass transfer coefficient as well as hydrodynamic properties. Once these parameters have been established, the scale-up/scale-down methodology indicates that the rate limiting step should be kept constant through the different scales so that any limitation of overall kinetics or selectivity envisioned in the large scale can be addressed at the laboratory scale.