6. What is FCC ???
• Fluid Catalytic Cracking (FCC) plays a key role in refinery as the primary
conversion process.The cat cracker holds the key to considerable profit,and
successful unit operation determines whether refinery can remain
competitive in market.
• The FCC uses microspheroidal catalyst,behaves like a liquid when properly
aerated by gas.The main purpose of FCC is to convert high-boiling
petroleum fractions---gas oil(portion of crude oil commonly boils from 330°C to 550°C.) to
high-value,high-octane gasoline and heating oil.
• The cat cracker must be operated reliably and efficiently. It must also be
operated safely and comply with GB Standards and local environmental
requirements. A typical FCC circulates tons of catalyst per minute,processes
various types of feedstock with hundreds of control loops,any of which can
make operation difficult.
7. Feed Preheat
Regenerator—Catalyst Recovery
Gas Plant
Riser—Reactor—Stripper
Main Fractionator
The FCC process is very complex. For clarity, the process description
has been broken down into six separate sections:
Treating Facility
10. Guidelines For Troubleshooting
01
03
Be a good listener
Do not draw any conclusions
before gathering all applicable
facts.
Evaluate causes of problems
Systematically list each
cause by brainstorming.
Gather historical background data
Examine similar problems
that occurred previously.
Examine goals and constraints to
verify the applicability of the present
operation
Due to changes in the feedstock,
catalyst,etc.
02
04
A successful troubleshooting assignment requires 4 points below:
12. Catalyst circulation is largely
influenced by the physical layout of the
unit and the fluidization properties of
the catalyst.
The first occurs when the maximum
circulation has been reached,and the
second occurs when the unit is
experiencing unstable circulation.
Two Types of Circulation Problems
13. Excessive pressure drop
downstream of the slide
valve.
Mechanical problems with
the slidel valve.
Three Causes for Insufficient Circulation
Insufficient pressure buildup
upstream of the slide valve
14. Mechanical Ways
Excessive pressure
drop
Insufficient
pressure
Higher catalyst circulation
usually requires opening the
regenerated and spent catalyst
slide valves.
Lowering the differential
pressure across the slide
valves.This makes valves
open further, until the unit
finds a new balance.
Higher circulation
increases the pressure
drop in the riser and in
the reactor cyclones
What we have done to
solve this.
