attention to all the other fuels (off-road diesel, bunkers, etc.) and make desulfurization of these stocks mandatory. High-sulfur fuel (3.5 wt%) currently used for
ships will be reduced to 0.5 wt.% in 2020 or 2025. Some ships might use scrubbers
to meet the new regulations and others could switch to a diesel fuel. Refiners will
find feedstock preparation, while costly, will greatly improve overall yields and
install hydroprocessing where the crude warrants. For high metal-laden crude or
those deficient in hydrogen, coking will be the preferred bottom processing route
followed by hydroprocessing of the coker gas oils or the FCC products.
FCC Reliability and Maintenance
Because of the importance of the FCCU to the profitability of a refinery, considerable effort has been made to improve the reliability and stream factor for the
process. Over the years, the average size of the FCCU has steadily increased.
Worldwide, the average is over 40,000 B/D while the US value tops 55,000
B/D. Many units are over 100,000 B/D. The cost of a single day of downtime for
units this large is from US$1 to 2 million.
In the 1960s, the average unit had a turnaround (TAR) every 2 years. By 1990,
this number was 3 years. In 2013, the average FCCU runs about 5 years between
scheduled shutdowns. While unscheduled shutdowns use to be common, they are
no longer expected or budgeted by refiners.
A survey of US refiners indicated most of the unscheduled shutdowns were due
to problems with:
Main air blower
Wet gas compressor
Expansion joints
Power failures
Slide valves
Refractory
Catalyst losses (cyclones)
Interlock trips
Each of these components has been improved over the years to eliminate these
unwanted run interruptions.
Rotating equipment uses better alignment techniques such as lasers and more
closely measures the temperature, the impurities in the water and oil, and vibrations
that signal a potential problem.
Expansion joints have been greatly improved. Better metallurgy is used now that is
resistant to failure. Steam purges that were used to keep catalyst from entering the joint
have been replaced with packing that better serves the purpose. Dual bellows with leak
detectors can give the refiner an opportunity to take steps to avoid a leak to the
atmosphere. These factors along with cold-wall designs that greatly reduce the potential movement of the main vessels have made expansion joint leaks a rare occurrence.
290
W. Letzsch
ships will be reduced to 0.5 wt.% in 2020 or 2025. Some ships might use scrubbers
to meet the new regulations and others could switch to a diesel fuel. Refiners will
find feedstock preparation, while costly, will greatly improve overall yields and
install hydroprocessing where the crude warrants. For high metal-laden crude or
those deficient in hydrogen, coking will be the preferred bottom processing route
followed by hydroprocessing of the coker gas oils or the FCC products.
FCC Reliability and Maintenance
Because of the importance of the FCCU to the profitability of a refinery, considerable effort has been made to improve the reliability and stream factor for the
process. Over the years, the average size of the FCCU has steadily increased.
Worldwide, the average is over 40,000 B/D while the US value tops 55,000
B/D. Many units are over 100,000 B/D. The cost of a single day of downtime for
units this large is from US$1 to 2 million.
In the 1960s, the average unit had a turnaround (TAR) every 2 years. By 1990,
this number was 3 years. In 2013, the average FCCU runs about 5 years between
scheduled shutdowns. While unscheduled shutdowns use to be common, they are
no longer expected or budgeted by refiners.
A survey of US refiners indicated most of the unscheduled shutdowns were due
to problems with:
Main air blower
Wet gas compressor
Expansion joints
Power failures
Slide valves
Refractory
Catalyst losses (cyclones)
Interlock trips
Each of these components has been improved over the years to eliminate these
unwanted run interruptions.
Rotating equipment uses better alignment techniques such as lasers and more
closely measures the temperature, the impurities in the water and oil, and vibrations
that signal a potential problem.
Expansion joints have been greatly improved. Better metallurgy is used now that is
resistant to failure. Steam purges that were used to keep catalyst from entering the joint
have been replaced with packing that better serves the purpose. Dual bellows with leak
detectors can give the refiner an opportunity to take steps to avoid a leak to the
atmosphere. These factors along with cold-wall designs that greatly reduce the potential movement of the main vessels have made expansion joint leaks a rare occurrence.
290
W. Letzsch