Current Activities
Hydrodynamic and Mass Transfer Parameters in Pilot-Scale Slurry Bubble Column Reactor Operating under Fischer-Tropsch Conditions
Since the discovery of Fischer-Tropsch (F-T) synthesis in 1920's, the technology has been successfully developed up to a commercial stage. The earliest reactor type utilized in Fischer-Tropsch synthesis was a fixed bed (ARGE) and in later stages, a circulating fluidized bed (Synthol) which were both commercially used by SASOL (South Africa). The other development in this technology is the "Fixed bed Fluidized bed" reactor which is commercially known as the "Sasol Advanced Synthol Reactor" (SASR).The alternative to the ARGE (fixed bed reactors, used in the recently commissioned Shell Malaysia plant at Bintulu) operating at low temperature is the slurry bed reactor. This type of reactor allows a much higher "online factor" when compared with the ARGE reactor which operates in short cycles due to catalyst deactivation and the consequence drop of wax yield and quality. In addition, a number of studies have shown that among the available Fischer-Tropsch technologies, the most cost effective one is the slurry bed process which is directed towards the production of middle distillates.
This research project focuses on the determination of the volumetric liquid-side mass transfer coefficient, (kLa), gas holdup, (εG) and the bubble Sauter mean diameter, (dS) for N2 and He in different F-T cuts (waxes) in the presence and absence of Fischer-Tropsch catalyst (iron and cobalt). The data are obtained in a pilot-scale slurry bubble column reactor of 0.3-m in diameter and 3-m high operating under Fischer-Tropsch conditions. The transient physical gas absorption technique is used to determine kLa, the manometric method is used to calculate the gas holdup, and the Dynamic Gas Disengagement (DGD) technique is employed to determine the bubble size and bubble size distribution. The Central Composite Statistical design technique is employed to investigate the effects of the pressure, temperature, catalyst loading, and superficial gas velocity on the reactor behavior. The hydrodynamic and mass transfer parameters to be obtained are empirically and statistically correlated and the resulting correlations can be used for F-T reactors scaleup.