Developments in Petroleum Refining - Spent Hydroprocessing Catalysts - page 11

Figure 2.5: Effect of tray levelness on liquids flow [From ref. 32 . Reprinted with permission].
of Swain et al. [38] , should be noted. It is emphasized that these improvements were achieved
for distillate feeds rather than for residual feeds.
Gragnani [39] reported that an additional operating time might be gained by employing the
inter-stage treatment of gaseous streams. Figure 2.8 shows schematics of the conventional
two-stage system and the same system but with the incorporated gas treatment. The
advantages of the latter are clearly evident from Fig. 2.9 and they can be ascribed to the
removal of gaseous hydrocarbons and H 2 S in particular. The build-up of the latter and a
gradual decrease in H 2 partial pressure will ultimately increase the H 2 S/H 2 ratio. It was
Figure 2.6: Effect of bypassing on sulfur in products [From ref. 32 . Reprinted with permission].