(99b) Solubility and Mass Transfer Parameters of Hydrogen in Vacuum Residues Under Hydroconversion Conditions

The volumetric liquid-side mass transfer coefficient (kLa) and equilibrium solubility (C*) for H2 were measured in two different vacuum residues (Zuata and Merey-Mesa) using one-liter agitated autoclave operating in a Gas Inducing mode under the typical conditions of hydroconversion of heavy residues. The effects of operating variables, including pressure (up to 55bar), temperature (up to 300ºC), mixing speed (up to 2000 rpm) and solid concentration (up to 40 wt%), on kLa and C* were investigated using the Central Composite Statistical Design and Analysis technique. The transient physical gas absorption method and a modified Peng-Robinson Equation-of-State were used to obtain kLa and C*, respectively.

Under the operating conditions investigated, kLa values for H2 were found to increase with increasing pressure, temperature and mixing speed, and to decrease with increasing solid loading. Also, the equilibrium solubilities for H2 in the two vacuum residues appeared to increase with pressure at constant temperature and increase with temperature at constant pressure. These data are indispensable for proper design and scaleup of slurry reactors heavily employed in hydro-processing of vacuum residues.