Completed Research
An Experimental Study of Gas-Liquid Mass Transfer at Fischer-Tropsch Reaction Conditions
Bhalchandra Madhav Karandikar, PhD, 1986
(Thesis: UMI Dissertation Publishing)
The effects of several important variables relevant to the slurry phase Fischer-Tropsch (FT) reaction, on volumetric gas liquid mass transfer coefficient (kLa) and gas solubility (C*) were examined in a surface aerated reactor (0.10 m diameter) and in a gas inducing type reactor (0.127 m diameter). Four gases: CO, H2, CH4, CO2, and three fractions: light (C6 - C11), medium (C11 - C22) and heavy (C22+) of an actual FT reaction product were used. An improved batch gas absorption technique, suitable for measurements at high temperature was employed in the determination of kLa and C* for gas/FT liquid systems and gas/FT liquid/water systems. A new procedure to estimate the solubility of water in FT liquid fraction has been developed. The proposed procedure does not require detailed phase analysis and involves the use of experimental total pressure versus temperature data only. The experimental gas solubility data revealed that solubilities of all gases in FT liquid fractions increased with pressure; Henry's law was found to be adequate to describe the effect of pressure. The estimated values of the solubility of water in the medium and heavy fractions of FT liquid showed an increase with temperature. The solubility of water in FT heavy fraction was always greater than that estimated for the FT medium fraction. In the presence of water, gas solubilities in FT fractions increased with pressure and temperature. Henry's law was also valid for all gas/FT liquid/water systems. The positive effect of water on gas solubilities was qualitatively explained. The kLa data indicated an increase of kLa values with pressure at stirrer speeds exceeding 700 rev min-1. Below 400 rev min-1, kLa data were found to be independent of pressure. The kLa values of all gases were found to be strongly enhanced by specific power input (P*/VL). The effect of pressure on kLa for all gases in FT fractions was not altered due to the presence of water. As before, the kLa values for all gases in FT medium and FT heavy fraction containing water showed a strong dependency on P*/VL.