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Topic
The Building Blocks of Robust Hydroprocessing Unit Operations
Presented by :
Saurabh Dhir
Shell India Markets Private Limited
Introduction
• An unplanned turnaround to replace catalyst early has severe financial consequences.
Primary source is anti-foam agents used in delayed cokers
Also found in some crudes and flow improvers used in drilling
Relatively mild poison
Silicon
Silicon removal involves reaction with hydroxyl groups present
on alumina support
For lighter feeds (naphtha and distillate), greater surface area
means increased Si capacity
Silicon
Heavier streams contain large molecules which cannot fully
penetrate the catalyst pellet
Use of large pore diameter catalysts in VGO service helps to
maximize surface area utilization
Silicon
Catalyst design for NHTs requires a balance between Si pick-
up and treating activity
Use of a inert, high surface area Si trap resulted in lower
exotherm and shorter cycle
Critical to balance Si pick-up & activity
Usually found in DAO and high end point VGO & HKGO; feeds
contain 2 to 15 ppm Ni & V
Removal involves kinetic reaction followed by deposition on the
catalyst surface
Ni & V traps are designed with an optimum pore size distribution
and balanced activity
Nickel & Vanadium
• A system designed for 7 ppm Ni & V observed rapid
increase in WABT after 1.5 years due to presence of Silicon
• A rebalanced load with increased demet provided stable
activity through 900 days on stream
Rebalanced load leads to longer cycle
• A FCCPT unit observed an increase in feed metals due to
change in crude source and quality
• Catalyst system was optimized from 2% demet to 15% demet
resulting in a 30% increase in cycle life
30% longer cycle with optimum load
• Found in many types of crude
• Severe poison
• Low level detection necessary (50 wppb)
Arsenic
• Reacts with active metal to form Nickel Arsenide
• Arsenic trap exhibits better retention of activity while picking
up high concentration of Arsenic
• MaxTrap[As] has 50% greater pick-up
Arsenic
• Higher pick-up capacity of the new MaxTrap[As] increased
the stability of the system resulting in a 30% increase in
cycle length
Longer cycle with MaxTrap[As]
• Specialized catalyst for high CCR feeds (DAO, deep cut
VGOs) with superior HDCCR and demet activity
• Ni & V removal in an FCCPT unit is higher with MaxTrap[CCR]
• Stable CCR conversion with MaxTrap[CCR]
MaxTrap[CCR]
➢ Balance demet and main catalyst volume while accounting for
unit limitations such as heat integration or maximum bed
delta T
➢ Take advantage of improved demet pick-up to extend cycles,
run higher margin crudes and heavier feeds
➢ More active and stable main catalysts allow operating
severity to be increased without sacrificing cycle life
➢ Use Catalyst Technology to maximize Profitability
Final Thoughts
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