FCC FUNDAMENTALS : OPERATIONS

& TROUBLESHOOTING

PRESENTED BY : S PALIT (DMPN)

CONCERNS IN FCC

•CATALYST LOSS

•COKING / FOULING

• FLOW REVERSAL

•CATALYST CIRCULATION

•HIGH REGEN TEMPERATURE

•AFTER BURNING

•AMOUNT & QUALITY OF PRODUCTS.

MAJOR PROBLEM

AREAS

CATALYST LOSS

CATALYST LOSS SYMPTOMS

MECHANICAL CONDITION

CHANGES IN

OPERATING CONDITION

CATALYST PROPERTIES

CAUSES OF CATALYST LOSS

MECHANICAL CAUSES

TRICKLE VALVES ARE STUCK CLOSE OR OPEN

DEFORMATION OF TRICKLE VALVE

FLAPPER OR TRICKLE VALVES DISENGAGED

TRICKLE VALVE & SPLASH PLATE

MECHANICAL CAUSES (CONTD)

SPALLED COKE OR REFRACTORY IN DIP LEG CAUSING RESTRICTION

HOLES ON CYCLONES

CRACKS ON PLENUM CHAMBER

DETACHED DIPLEG

A TYPICAL CYCLONE

MECHANICAL CAUSES (CONTD)

IMPROPER STEAM / AIR RESTRICTION ORIFICES ON PURGES CAN LEAD TO CATALYST ATTRITION, THEREBY GENERATING FINES

CATALYST LOSS DUE TO OPERATIONS

INCREASE IN

CATALYST

CIRCULATION

INCREASE IN

STEAM TO

REACTOR

AIR TO

REGENERATOR

LOWERING OF

OPERATING

PRESSURE

INCREASE OF CATALYST

LOADING TO CYCLONES

CATALYST LOSS DUT TO CATALYST

TROUBLESHOOTING

TROUBLESHOOTING

OPERATIONAL

VERIFY THE CATALYST LEVELS

IN REACTOR AND REGENERATOR

CHECK THE CYCLONE VELOCITIES

AND COMPARE WITH THE DESIGN

REDUCE CAT-OIL RATIO

CHECK PURGE POINT ROV

COKING / FOULING PROBLEM

FREQUENT CAVITATION AND LOSS OF SUCTION OF

BOTTOM PUMP

INCREASED

PRESSURE DROP

IN MCB

EXCHANGERS

HIGH PRESSURE

DROP ACROSS Rx

VAPOUR LINE

POOR HEAT TRANSFER IN

MCB PUMPAROUND

CIRCUIT

REASONS FOR COKING / FOULING

CATALYST PROPERTIES RESPONSIBLE

FOR COKING

OPERATIONAL CONDITIONS

RESPONSIBLE FOR COKING

HIGH MCB

LEVEL

LONG

RESIDENCE

TIME

LOW WASH

LIQUID FLOW

LOW ROT

LONG RESIDENCE

TIME IN VAPOUR

LINE

FEED PROPERTIES LEADING TO

COKING

ASPHALTENES AND RESID IF

NOT CONVERTED IN RISER,

LEADS TO COKING

MECHANICAL CONDITIONS LEADING

TO COKING

TROUBLE SHOOTING

TROUBLESHOOTING

IMPROVE FEED ATOMISATION

INTRODUCE FEED WHEN REACTOR IS ADEQAUTELY HEATED DURING UNIT START UP

KEEP THE VELOCITY IN MCB EXCHANGER > 2.1 m/s

TROUBLESHOOTING

MAINTAIN MCB TEMP < 360 deg C

MAINTAIN 1ST TRAY IN THE BOTTOM TEMP < 420°C BY PROVIDE ADEQUATE WASHING LIQUID TO MCB

MAINTAIN HIGH REACTOR TEMPERATURE IF POSSIBLE

FLOW REVERSAL

REGENERATOR

REACTOR

REGENERATOR

NORMAL CATALYST FLOW PATH

PROPER PRESSURE

BALANCE ACROSS

REACTOR AND

REGENERATOR

AIDS CATALYST

MOVEMENT

FLOW REVERSAL

PHENOMENON OF FLOW REVERSAL

THE HOT FLUE GAS FLOW TO

REACTOR AND TO COLUMN IF THE

PRESSURE DIFFERENTIAL ACROSS SPENT

CATALYST SLIDE VALVE BECOMES

NEGATIVE

OIL SOAKED CATALYST TO FLOW

REVERSE FROM RISER TO

REGENERATOR IN CASE THE

DIFFERENTIAL PRESSURE ACROSS

REGENERATED CATALYST SLIDE VALVE BECOMES

NEGATIVE

CAUSES OF FLOW REVERSALS

MAB TRIPPING

PRESENCE OF WATER IN FEED

HIGH OPENING OF SLIDE VALVES

SUDDEN LOSS OF REACTOR / REGENERATOR LEVELS

FAILURE OF REACTOR TEMP / LEVEL CONTROL

PROTECTION FROM FLOW REVERSAL

• INDEPENDENT LOW DIFFERNTIAL PRESSURE OVERRIDE CONTROL FOR SLIDE VALVES

• CHECKING OF FEED TANK HEATING COIL OUTLET AND REGULAR DRAINING OF FEED SURGE DRUM

• EMERGENCY SHUT DOWN

HIGH REGENERATOR TEMPERATUR

HIGH REGENERATOR TEMPERATURE

HIGH REGENERATOR TEMPERATURE

HIGH REGENERATOR TEMPERATURE

HIGH REGENERATOR TEMPERATURE

HIGH REGENERATOR TEMPERATURE

RAISE CAT / OIL RATIO

IMPROVE FEED ATOMISATION

IMPROVE STRIPPING IN

REACTOR

USE METAL PASSIVATOR

REMEDIES

AFTER BURNING

CAUSES OF AFTER BURN

POOR AIR / CATALYST

DISTRIBUTION

LIFT LINE WITH AIR RING AIR

DISTRIBUTION PROBLEM

CAUSES OF AFTER BURN

LIFT LINE WITH AIR RING CAT

DISTRIBUTION PROBLEM

CHANNELING OF CATALYST

IN CURVED LIFT LINE

CAUSES OF AFTER BURN

REGEN INTERNALS CREATE

TWO STAGE REGENERATION

CATALYST ENTERS ONE SIDE

OF REGENERATOR

CAUSES OF AFTER BURN

EFFECT OF HIGH DENSITY CATALYST ON

AIR DISTRIBUTION

REASONS OF AFTERBURNS

OPERATING CAUSES

EXCESS AIR

LOW CATALYST

RESIDENCE TIME

MECHANICAL

CAUSES

DAMAGED AIR RING

DAMAGED CATALYST

DISTRIBUTOR

AFTER BURN REMEDIES

INCREASE STRIPPING STEAM RATE.

INCREASE THE CATALYST RESIDENCE TIME : RAISE THE REGENERATOR CATALYST BED LEVEL.

REDUCE FEED CCR

INCREASE CAT / OIL BY QUENCHING

CATALYST CIRCULATION

THE LIMITATION IN CATALYST CIRCULATION

WILL LIMIT THE T’PUT OF THE UNIT.

EXTREME HIGH CAT CIRCULATION PROBLEM

WILL LEAD TO UNIT SHUTDOWN

CATALYST CIRCULATION PROBLEM

SYMPTOM:

SLIDE VALVE FAR TOO OPEN

EVIDNECE:

SLIDE VALVE OPENING INDICATIONS

CAUSES:

GATE OR ORIFICE TOO SMALL FOR FLOW

SOLUTIONS:

REPLACE WITH APPROPRIATE SIZE VALVE

INCREASE REGEN PRESSURE / BED LEVEL

CATALYST CIRCULATION PROBLEM

REASONS:

SYMPTOM: LOW DELTA P ACROSS SLIDE

VALVE

HIGH PRESSURE D/S

OF SLIDE VALVE

LOW PRESSURE U/S

OF SLIDE VALVE

WHEN HIGH PRESSURE D/S

HIGH DP ACROSS RISER

HIGH CAT CIRCULATION

LESS RISER GAS AT RISER

BASE

HIGH DP ACROSS VAP

LINE

VAP LINE COKING

HIGH RXR VAP LOAD

REASONS

CAUSES

WHEN HIGH PRESSURE D/S

HIGH DP ACROSS MF

HIGH VAP / LIQ RATES

PLUGGED TRAYS

HIGH DP ACROSS MF

O/H CIRCUIT

CONDENSER FOULING

HIGHER RATES OF

LIGHTER HC

REASONS

CAUSES

WHEN HIGH PRESSURE D/S

HIGH DP ACROSS

RISER

REPLACE RISER BEND

INCREASE RISER STEAM

HIGH DP ACROSS VAP

LINE

COKING REDUCTION

VAP LINE CLEANING

DURING S/D

PROBLEMS

SOLUTIONS

WHEN HIGH PRESSURE D/S

HIGH DP ACROSS MF

ADJUST PUMP AROUND RATES

ADD TOP OR SIDE PUMP AROUNDS

HIGH DP ACROSS MF O/H

CIRCUIT

CONDENSER CLEANING

INCREASE WATER WASH

TO CONDENSERS

PROBLEMS

SOLUTIONS

WHEN LOW PRESSURE U/S

INSUFFICIENT PRESSURE BUILD

UP IN STAND PIPE

DEFLUIDIZATION IN STAND PIPE

DE-AERATION IN STAND PIPE

LOW CATALYST DENSITY IN STAND PIPE

IMPROPER PLACEMENT OF AERATION TAPS

PLUGGED RO

REASONS

CAUSES

WHEN LOW PRESSURE U/S

DEFLUIDIZATION IN STAND PIPE

CHECK CATALYST PROPERTIES

DE-AERATION IN STAND PIPE

INCREASE AERATION GAS

FLOW TO MAXIMIZE PRESSURE BUILD UP

IMPROPER PLACEMENT OF AERATION TAPS

PLUGGED RO

FLUSH RO

SOLUTIONS

PROBLEMS

LOSS IN PRODUCTS –

PROBLEM INDICATORS

CONVERSION

DRY GAS YIELD

GASOLINE YIELD

PROBLEM AREAS

FEED QUALITY

CATALYST QUALITY

OPERATING CONDITION

MECHANICAL DEFECT

LOW CONVERSION

FEED QUALITY

INCREASE IN METALS

CONTENTS

HIGH FBP FEED

INCREASE IN FEED

AROMATICITY / NAPHTHENECITY

CATALYST PROPERTIES

LOW CATALYST ACTIVITY

LOW SURFACE AREA

HIGH CRC

LOW CONVERSION

OPERATING CONDITIONS

LOW CAT / OIL RATIO

LOW ROT

LOWER RATE OF FEED

ATOMIZING STEAM

LOW F-CAT ADDITION

RATE

MECHANICAL CONDITIONS

PROBLEM IN FEED NOZZLE

PROBLEMS IN REGEN

INTERNALS

TROUBLESHOOTING

CHECK FEED STOCK PROPERTIES

K-FACTORS, ANILINE POINT, SP. GR

CHECK E-CAT PROPERTIES

VERIFY ACCURACY OF INSTRUMENT INDICATIONS

OF RR SECTION

CARRY OUT PRESSURE SURVEY OF FEED NOZZLES,

AIR RINGS, ETC

HIGH DRY GAS YIELD

FEED QUALITY

INCREASE IN METALS

CONTENTS

INCREASE IN FEED

AROMATICITY / NAPHTHENECITY

CATALYST PROPERTIES

LOW CATALYST ACTIVITY

LOW SURFACE AREA

HIGH CRC

HIGH DRY GAS YIELD

OPERATING CONDITIONS

HIGH ROT

LOWER RATE OF FEED

ATOMIZING STEAM

INCREASE IN RECYCLES

MECHANICAL CONDITIONS

PROBLEM IN FEED NOZZLE

PROBLEMS IN REGEN

INTERNALS

DECREASE IN GASOLINE YIELD

FEED QUALITY

HIGH FBP FEED

INCREASE IN FEED

AROMATICITY / NAPHTHENECITY

CATALYST PROPERTIES

LOW RARE EARTH CONTENT

LOW ZEOLITE CONTENT

LOW UNIT CELL SIZE

DECREASE IN GASOLINE YIELD

OPERATING CONDITIONS

LOW / HIGH ROT

DECREASE CAT / OIL

RATIO

HIGH DOSING

OF ZSM -5

MECHANICAL CONDITIONS

PROBLEM IN FEED NOZZLE

PROBLEMS IN REGEN

INTERNALS