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