Fluid Catalytic Cracking Unit
FCC OPERATIONSFCC OPERATIONS& SALIENT DESIGN ASPECTS
17TH MARCH 2011
V.SRIKANTHSENIOR MANAGER(NHT/ISOM)
CONTENTS
• GENERAL• FCCU SCENARIO • CRACKING REACTIONS• FLUIDISATION• CATALYST• PROCESS DESCRIPTION• PROCESS VARIABLES• CRACKER EQUIPMENT
GENERAL
GENERAL
PRODUCTS OF PETROLEUM CRUDE OIL
• Gas (Methane & Ethane) Industrial fuel• LPG (Propane & Butane) Household fuel• Naphtha Industrial feed / Motor Spirit (MS)• Kerosene / ATF Household fuel / Aviation Fuel• Diesel Automobile fuel
• Vacuum Gas Oil No direct end use• Lube oil Lubricating oil• Paraffin Wax Candle, Matches, Water proof coating• Vacuum residue (Bottom) Industrial fuel, Asphalt
GENERALYield vs Price
0
100
200
300
400
500
600
700
800
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Cum yield %wt
Price $/ton
Average Crude Price = 377 $/t
Stocks
PP
LUB
ATFMS KEROLoc HSD
LO Byp
Loc Naph
LPG
Exp HSD
Exp FO
BIT
Loc FO
SULP
BS
WWH
MWC3
Exp Naph
F&L
Base Case GRM = 4.75 $/bbl
CRU Feed
FCC Feed
HCU Feed
VBU Feed
PDU Feed
GENERAL • PRIMARY PROCESSING UNIT• SECONDARY PROCESSING UNIT• Secondary units are installed to:
• Upgrade lower grade products • Increase value added products• Maximise production of products in demand• Production of specialty products• Minimise production of undesired products• To meet Product / Environmental specifications
GENERAL
MEANS OF VALUE ADDITION
• Thermal Cracking High value light products• Catalytic Cracking - do -• Hydro Cracking - do -
• Extraction / Filtration Lube base oil / Wax• Iso-Dewaxing Lube base oil
CATALYTIC CRACKING
• Cracking VGO into low molecular weight products of high value, by application of heat and in the presence of catalyst
• Good selectivity – for producing desired products• Good quality products (Mainly mono-olefins)• Specialty products (Propylene, Butylenes)• High initial investment• Low fuel and loss
GENERAL
WHY FCCU? • Benefits of FCCU:
• Converts heavy ends into desired lighter products • Reaction involves regrouping of molecules to
provide the quality product• Flexibility in product pattern• Production of lower molecular weight special
products like Propylene, Butylenes• Reduces the Sulphur content in liquid streams by
converting into H2S • Minimise production of undesired products
FLEXIBILITY IN FCCFLEXIBILITY IN FCC
Easy Catalyst / Additive Loading & WithdrawalNo Hot SpotAutomatic Balancing of Heat / PressureFeed Quality VariationsLow pressure , Moderate temp.
FCC is Flexible and Thus Growing
Flexibility of Operating FCC Unit
Optional (Heavy
Naphtha)
Optional (HDT LCO)
1.4 (HCO)Recycle, CFR
> BaseBase< BaseCatalyst/ Oil Ratio
> BaseBase < BaseResidence Time
538 – 560527 – 538449 – 510Reactor Temp. °C
Light Olefin Mode
Gasoline Mode
Middle Dist. Mode
Operating Conditions
Flexibility of Operating FCC Unit
7.07.29.2HCO, LV%
10.113.937.5LCO, LV%
55.260.043.4C5+ gasoline, LV %
20.515.49.8C4, LV%
16.110.76.9C3, LV%
4.73.22.6C2, wt.%
1.01.00.7H2S, wt.%
Light Olefin Mode
Gasoline Mode
Middle Dist. Mode
Product Yield
FCC BALANCES
Mass BalanceHeat BalanceCoke BalancePressure Balance
FCC is floating on balances
FCCU SCENARIO
• 400 FCC Units in World
• Major Secondary Process since 1942
• Major source of high value lighter hydrocarbon
• Complex, Interlinked but Flexible
• Flexible operation modes: LPG, MS & Diesel
• Continuous developments in Design
• Development of Catalyst & Additives
FCC is Workhorse of Refinery
FLUIDISED CATALYTIC CRAKING
FCC/RFCC UNITS IN INDIAS.
NOREFINERY CAPACITY
MMTPALICENSOR YEAR OF
COMMISSIONING
1 HPCL(BOMBAY) 0.40 ESSO 1954
2 BPCL( BOMBAY) 1.20(0.60) SHELL(MODEL IV) 1995(1955)
3 HPCL(VISAKH) 0.95(0.40) EXXON(ESSO) 2000(1957)
4 IOCL(GUJARAT) 1.4 UOP 1982
5 IOCL(MATHURA) 1.00 UOP 1983
6 CPCL (MADRAS) 0.78(0.60) UOP 2004(1985)
7 BPCL(BOMBAY) 0.85 SWEC(UOP) 2002(1985)
8 KRL(COCHIN) 1.75(1.00) UOP 2005(1985)
9 HPCL(VISAKH) 0.60 UOP 1985
10 IOCL(PANIPAT) 0.70 S&W 1997
11 Reliance (Jamnagar) 8.0 UOP 1998
13 IOCL(BR) – RFCC 1.4 S&W 2002
12 IOCL(HR) – RFCC 1.0 S&W 2001
BLOCK FLOW DIAGRAM OF MODERN REFINERY
CRACKING REACTIONS
Process Variables 19
Principal Reaction Paths
• Thermal Cracking
• Catalytic Cracking– Primary Reactions– Secondary Reactions
Process Variables 20
Primary Reactions
• Paraffin Smaller paraffin + olefin
• Alkyl naphthene Naphthene + olefin
• Alkyl aromatic Aromatic + olefin
• Multi-ring naphthene Alkylated naphthenewith fewer rings
Process Variables 21
Secondary Reactions
• Olefin + paraffin Paraffin + olefin
• Olefin + naphthene Paraffin + aromatic
• Olefin + olefin Paraffin + diolefin(or coke)
• Olefin + olefin Paraffin + aromatic
FLUIDISATION
FLUIDIZATION REGIMESIN FCC
Name FCC Section Gas VelocityM/Sec
Bed Density,KG/M3
Packed Bed -- < 0.05 700 - 850
Min Fluidization Standpipe .01 - .05 700 - 800
Bubbling bed Stripper .05 - .30 600 - 750
Dense Bed Regenerator .30 - .70 400 - 600
Turbulent Bed -- .70 - 1.1 300 - 500
Fast Fluid Bed Combustor 1.1 - 3.0 100 - 300Pneumatic Flow Riser 2.0 - 20.0 30 - 100
FLUIDIZATION REGIME IN FCCU
Air
Riser
Stripper
LC
TC
V=0.3-0.7V=2-20
V=0.01-0.05
V=0.05-0.30
ρ= 400-600ρ= 700-800
ρ= 30-100
ρ=700-800
CATALYST
FCC CATALYST
MATRIX
ZEOLITERe-EARTHS
CLAY
PERFORMANCE FEATURES OF FCC CATALSYTS
Zeolite type and level of rare earth
Particle size Distribution, density
Density, Attrition resistance
Zeolite type, matrix type, traps
Zeolite type matrix type and amount
Activity and stability
Fluidization
Unitretention
Metal tolerance
Selectivity
FCC CATALYST ADDITIVES
• Olefin maximisation additives
• Octane enhancement additives
• Bottom Cracking Additives (BCA)
• DeSOx additives
• Metal traps
• Gasolene Sulphur Reduction (GSR) additives
PROCESS DESCRIPTION
UOP Side by Side Fluid Catalytic Cracking Unit Flue
GasFlue Gas
Slide Valve
Regenerator
Spent CatalystSlide Valve
Regenerated Catalyst
Slide Valve
Air
Raw Oil
Stripping Steam
Reactor
Products to Main Column
Process Flow and Control 32
Regenerated Catalyst Slide
Valve Control
ReactorTIC
High Temperature Closes Slide Valve
Low Differential Pressure Signal Closes Slide Valve
PDI
Low Signal Selector
PDIC
PDTPI
PI
(readable from slide valve)
Regenerated Catalystfrom Upper Regenerator
RegeneratedSlide Valve
Handwheel Actuator
Selector Switch
FCDA
ZIDG
<
Process Flow and Control 33
Spent CatalystSlide Valve
ControlLow Level
Signal ClosesSlide Valve
PDIC
PI
Reactor
Low DifferentialPressure Signal
Closes Slide Valve
LIC
Low Signal Selector
PI
PDT
ZIPDILI
Readable from Slide Valve
Actuator Selector Switch
DG(LAHL)
LT
Spent Catalyst to Regenerator
>
Actuator
DA
DG
FC
DG
LICLT
DTDI
DG
DG
DG
DG
Process Flow and Control 34
Conventional FCC Flue Gas System(without Power Recovery)
Flue GasSlide Valves
OrificeChamber
CO Boiler ElectrostaticPrecipitator
Flue Gas
Air
Steam
Water
PIC PDIC
>HSS
Air
Signal fromReactor
Pressure Tap
FCC-PC002
Process Flow and Control 35
Main Column Bottoms
Circulation
Raw Oil
MCBProduct
BFW
SteamReactorProductVapor
∑
LIC
FI
FIC
CW
MCBQuench
Disc and DonutMinimum Flow
Raw Oil
LIC
DebutanizerReboiler
HCN StripperReboiler
FIC FIC
FIC
FIC
FIC
Torch OilPump Flushing Oil
FCC-PC401
FIC
PROCESS VARIABLES
Process Variables 37
Process Variable Effects
Increased CombinedFeed TemperatureIncreased RecycleRateIncreased ReactorTemperatureIncreased ReactorPressureIncreasedRegenerator PressureIncreased CatalystCirculation Rate atConstant ReactorTemperature(Increased CatCooler Duty)
Con
vers
ion
Gas
Yie
ld
LPG
Yie
ld
Oct
ane
Ole
fin C
onte
nt
Aro
mat
ic C
onte
nt
LC
O A
rom
atic
C
onte
nt
Cok
e Y
ield
Reg
ener
ator
Tem
p
Cat
alys
t/Oil
Cat
alys
t Ent
rain
men
t
Cyc
lone
Eff
icie
ncy
Req
’dSt
ripp
ing
Stea
m R
ate
Affected Variable
Adjusted Variable
Gasoline
Change in Affected Variable: –increases; – decreases
CRACKER EQUIPMENT
HARDWARE SUBSYSTEMS FOR FCCHARDWARE SUBSYSTEMS FOR FCC
Feed distributorRiser termination deviceStripper with efficient internalsCatalyst & air distributors in
regeneratorCatalyst coolerCyclonesFlue gas scrubber
HARDWARES PLAY MAJOR ROLE IN FCC
Equipment 40
Feed Distributor Historical Development
• Bayonet• Showerhead• Premix• Lift Gas• Optimix
Equipment 41
Reactor Riser Feed DistributorJet Nozzle Type
FCC/DS-R00-98
AbrasionResistant
Lining AbrasionResistant
Lining
Drain andVacuum
Connection
Equipment 42
Elevated Optimix Feed Distributor
Equipment 43
Optimix Feed DistributorWork Point
High DensityRefractory Lining
Welding NeckFlange
SteamConnection
FeedConnection
Ceramic FiberBlanket Insulation
Reactor RiserFeed Distributor
AbrasionResistant
Lining
Equipment 44
Reactor Riser Disengager Designs
• Down-Turned Arms• Vented Riser• Direct-Connected Cyclones• Suspended Catalyst Separation• Vortex Disengager System and
Vortex Separation System
Equipment 45
Reactor Riser Disengaging Devices
T-TypeDisengager
Down TurnedArm
VentedRiser
Direct-ConnectedCyclones
Equipment 46
Modern Reactor Riser Disengaging Devices
Vortex Disengager Stripper Vortex Separation System
Equipment 47
Reactor WYE Section• Hot Wall vs. Cold Wall• Cold Wall Advantages
– Less Thermal Expansion– No High Temperature Metallurgy– Metal Temperature Out of Creep
Range– No Stress Relief– Increased Operating Life
Equipment 48
Hot Wall “WYE”
RegeneratedCatalyst
ChargeBlast Steam
External Insulation
3/4” AbrasionResistant Lining
304H SS
Riser
Equipment 49
Cold Wall“WYE”
RegeneratedCatalyst
Blast SteamCharge
5” RefractoryCement Lining
Riser
Carbon Steel
Equipment 50
Catalyst Stripper
StrippingSteam
StrippingSteam
Fluffing Steam
AbrasionResistant Lining
Riser
Stripper Shell
Insulation
FCC-E005
Bubbling Bed Regenerator
T
REGENERATOR PLENUMCYCLONE SUPPORTS
REFRACTORYLINING
REFRACTORYLINING
EXTERNALLINING
SPENT CATALYSTDEFLECTOR
AIR DISTRIBUTOR
SECOND STAGECYCLONES
FIRST STAGECYCLONES
THERMOCOUPLES(1each cyclone)
TRICKLEVALVES
SPENT CATALYSTSTANDPIPE
TI’s
LEVEL ANDPRESSURE TAPS
MANWAYS
CATALYSTWITHDRAWAL
OPEN PRIMARYCYCLONE DIPLEG
TERMINATIONSLEVEL AND DENSITYPRESSURE TAPS
MANWAY
TORCH OIL
REGENERATEDCATALYSTSTANDPIPE
FCC-E003
Equipment 52
Pipe Air Grid
Equipment 53
Plan of Air Grid
PLAN(Total Number of Arm Jets Required: 1024)
= Open Jets: 850= Plugged Jets: 174
Equipment 54
Jet Detail
FCC/DS-R00-65
Equipment 55
Cyclone-Catalyst Fines Collector
Catalyst-LadenGas Inlet
Catalyst-FreeGas OutletGas Out
Catalyst-LadenGas Inlet
DisengagingHopperCatalystOutlet
Dip Pipe
Stream Pattern--Lower Portion
Stream Pattern--Upper Portion(Principally Finer Particles)
Equipment 56
Regenerator Cyclones
• First Stage– Inlet Velocity Shall Not Exceed 65 ft/sec (19.8 m/sec)– Outlet Velocity Shall Not Exceed 80 ft/sec (24.4 m/sec)– Ratio of Barrel Area to Inlet Area Shall be 3.7 Minimum
Equipment 57
Regenerator Cyclones (continued)
• Second Stage– Inlet Velocity Shall Not Exceed 75 ft/sec (22.9 m/sec)– Outlet Velocity Shall Not Exceed 120 ft/sec (39.6 m/sec)– Ratio of Barrel Area to Inlet Area Shall be 4.3 Minimum– Minimum Barrel Diameter is Equal to First Stage Barrel
Diameter
Equipment 58
Regenerator Cyclones (continued)
• Both Stages– Ratio of Cyclone Length to Barrel Diameter
Shall be 5.0 Minimum– Projected Apex of Main Cone Shall be a
Minimum Distance of 0.3 Times Barrel Diameter Above the Outlet of the Dust Hopper
Equipment 59
Cyclone Dipleg Termination
• Trickle Valve• Counterweighted Flapper
Valve• Submerged
Equipment 60
Trickle Valve
Hinge
Flapper Plate
Stop
3-5º From Vertical
Equipment 61
Weighted Flapper Valve
Equipment 62
UOP Plenum Chamber Designs
FCC/DS-R00-104
ExternalPlenum
InternalPlenum
ExternalManifold
Equipment 63
Orifice ChamberFlow
Internal Manways
Carbon Steel Shell
304H Internals
RefractoryHexmesh
Equipment 64
Orifice Chamber
• Used When Regenerator Pressure is Controlled by Flue Gas Slide Valve
• Reduces Pressure Drop Across the Slide Valve
• Grid Hole Erosion
Equipment 65
Grid Section of Orifice ChamberGrid Holes
Rings
Plan of GridCL Grid
3/4” AbrasionResistant LiningR
ing
#1R
ing
#2R
ing
#3R
ing
#4
1”
Grid Section
CL Grid
Equipment 66
Orifice Chamber GridsFirst Grid: Last Grid:
Equipment 67
Electrostatic Precipitator
Equipment 68
ESP Fines Collection Equipment
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