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"Fluidized Catalytic Cracking ­ Operations & Salient Design Aspects "

Sanjiv Singh

General Manager IOCL, Panipat Refinery

(26th August, 2010) NIT, Jallandhar

"Fluidised Catalytic Cracking"

Presentation Outline ­

Background

Refining Processes FCC ­ Major Secondary Process

FCC

General Description (Rx ­ Rg & Recovery section) Process Flow Diagram FCC Heat Balance FCC Sub Systems Process Variables Catalysts & Additives Present Trend

Questions

REFINING PROCESSES

Primary Process

No chemical change Only physical separation Atmospheric Distillation Vacuum Distillation

Secondary Processes

Desired chemical reactions Carbon rejection processes ( ----- Cracking) Hydrogen addition processes ( Hydro -----)

Treating Processes

SECONDARY PROCESSES CRABON REJECTION Cracking

Thermal

Delayed Coking Vis-Breaking

Catalytic

Fluidised Catalytic Cracking RFCC Indmax

CATALYTIC CRACKING

Catalytic conversion of VGO (Resid) in FCC Catalyst remains in various stages of fluidisation Continuous regeneration of catalyst Continuous movement of catalyst between Rx & Rg Gives LPG and high octane gasoline Low Cetane TCO Processing resid may require hardware changes Resid processing

requires hardware changes requires higher catalyst addition may require heat removal from regenerator may require feed pretreatment products' hydrotreatment may be required

FCC UNIT

To MF

AIR

Steam

Steam Steam

AIR

Back flush

Steam

AIR

AIR AIR

HCO Steam

FF Steam

FCC FRACTIONATION SECTION

M AIN FR ACTIO NATO R

E T O W E T G A S C O M PR E SS O R V

R E FLUX

MAIN FRACTIONATOR

G AS P LA NT LE A N O IL FE ED CW

RIC H S PO NG E O IL

LC O

STRIP REBO ILER FEED BFW DM W ATER

D IST . P R O D UC T HC O

FEED DeC4 REBO ILER

E FE E D CW PU M P SE A L O IL

Q U EN C H F EE D

RE CY C LE

RE CY C LE F ILT E R

FEED HPS BFW

R E TU RN TE M P W A T ER

DE CA N TE D O IL

FCC GAS CON. SECTION

WASH WATER 2 AIR COOLERS WILD NAPHTHA DEBUTANISED GASOLINE (LEAN OIL) 5 OFF GAS TO DEA LEAN SPONGE OIL RICH SPONGE OIL SPONGE OIL ABSORBER 4 C3's & C4's PRODUCT STRIPPER WATER 3

INTERSTAGE DRUM 1 VAPOURS FROM MAIN COLUMN O/H RECEIVER

HPD PRESATURATOR

1ST SATGE

2ND SATGE

GAS COMPRESSOR

LIGHT GASOLINE PRODUCT

WASH WATER

HEAVY GASOLINE PRODUCT

DEBUTANISER

GASOLINE STRIPPER

LEAN OIL TO PRIMARY ABSORBER

5

PRIMARY ABSORBER

AIR COOLERS

RFCC UNIT

FCC Heat Balance

Regenerator Flue gas Spent Catalyst Products Heat of Coke Combustion Heat losses Heat Losses Reactor

Heat of Reaction Recycle Regenerated Catalyst Regeneration Air Feed Pre-heater Fresh Feed

HEAT BALANCE

Heat generated by burning coke Heat consumed in Rx and ..... Cat Cracker adjusts itself to stay in heat balance Links Dependent and Independent variables

Independent Variables

Rx Temperature Feed Preheat Temp Recycle rate / CFR Fresh cat activity / selectivity

Dependent Variables

Regenerator Temp Cat circulation rate Conversion Air requirement

FCC Heat Balance

Reactor Heat Requirements

Heat of reaction (-) Heat up feed (-) Heat up recycle (-) Heat up stripping steam (-) Losses (-)

Regenerator Heat Production

Heat of combustion of coke Heat up air (-) Heat up coke (-) Losses (-)

Heat transferred by catalyst

(C/O) Cpcat(Tregen-Treactor)

HEAT BALANCE

Delta Coke

Difference between CSC and CRC Amount of coke formed on cat per pass in Rx Equal to the amount of coke burnt off in regenerator A function of

Process parameters Mechanical parameters Feed quality Catalyst type

Coke yield Del coke

= =

C/O (CSC ­ CRC) (CSC ­ CRC) = Coke yield / C/O

HEAT BALANCE

Delta Coke is decreased by

Increased Cat / Oil ratio

By increasing Rx temp By reducing CO combustion level By reducing combined feed temperature

Improved feed nozzle dispersion Better stripping Decrease in recycle slurry rate Improved feed quality

Higher API, K factor Lower CCR, boiling range

Coke selective catalyst

HEAT BALANCE

Typical Effects of Delta Coke

Regen temp

Cat / oil

Coke yield wt%

Delta coke ---------

HEAT BALANCE

Types of Delta Coke

Catalytic coke

Coke formed by cracking reactions Influenced by the type of catalyst

Cat / Oil coke

Unstripped HC entrained by catalyst, flowing through stripper Independent of any beneficial chemical reaction Has highest heat of combustion (H2 presence) Affected by strippability of catalyst (pore size and surface area)

HEAT BALANCE

Types of Delta Coke

Contaminant Coke

Coke produced as byproduct of contaminant metals (V, Ni, Cu, Fe) dehydrogenation activity Can be a substantial % of total coke for a metal laden catalyst Use of metal passivators can reduce this coke

Additive Delta Coke

Due to feed CCR Goes directly to the coke on the catalyst Substantial for resid feeds

HEAT BALANCE

Typical Delta Coke Break Down

Zeolite low metal Feed Gas Oil Delta Coke wt% cat % Catalytic 0.52 65 Cat / Oil 0.12 15 Contaminant 0.12 5 Additive/Concar 0.04 15 Zeolite high metal Resid wt% cat % 0.40 29 0.10 14 0.40 29 0.50 28

Total 0.80 100 1.40 100 Rx heat requirement = Rg heat prod = Heat transfer by catalyst

FCC SUBSYSTEMS

FCC SUB SYSTEMS

Riser

Vertical pipe through which catalyst and oil move up in the reactor, RTDs May be external or internal Refractory lined, cold walled or hot walled Height and ID depend on unit capacity and design Feed entry through feed nozzles, separate nozzles for recycle HC residence time 1 ­ 3 sec (cat residence time 2 ­3 times higher) Vapour velocity 65 ­ 85 ft/sec

FCC SUB SYSTEMS

Feed Injection System

Rapid feed vaporization and uniform mixing with catalyst

Reduce non-selective cracking & thermal reaction

Better feed nozzle design using dispersion steam

Enhance vaporization Avoid backmixing of hydrocarbons Avoid thermal cracking Reduce hydrocarbon partial pressure

Feed coke = 1 (feed CCR) where, 1 = f1(feed vaporization/distribution)

Reduce coke make & improve yields

Feed Nozzle Designs

ATOMAXTM Nozzle

Steam

Slotted Tip

Proprietary Internals

Oil

Oil

Slotted Tip Oil Steam

Steam

Slotted Tip

Steam Oil

Multiple open pipes in common cap

Slotted Tip

Impact-type Nozzle

High P

Open Pipe Showerhead Nozzle

Modern Feed Nozzles

Spray Pattern

More even distribution of oil across the spray

FCC SUB SYSTEMS

Reactor

Reactor vessel provides disengaging space for catalyst Houses Riser Termination Device Houses cyclones Usually cold walled with internal refractory lining Reactor stripper at the bottom of reactor vessel

FCC SUB SYSTEMS

FCC SUB SYSTEMS

Reactor Stripper

Surrounds the upper portion of the riser Fitted with internals / baffles to enable stripping of the catalyst using superheated steam. Cat flux 500 ­ 700 lb/min-ft2 Stripping steam rate 2 ­ 5 lb per 1000 lb of catalyst Excess stripping steam may not be beneficial Catalyst residence time 1 ­ 2 minutes Pre stripping rings at dip leg bottoms Performance can be assessed by Hydrogen on coke

Inside Stripping Section

Strippable coke = Function of stripper efficiency, riser operation & conversion level

Catalyst Level Steam

Reactor Stripper

Reactor Riser

Riser Termination Devices

Denser catalyst particles have more momentum ­ tend to continue in a straight line & get separated from gas stream which more readily take a tortuous flow path

Reactor Riser Disengaging Devices

T-Type Disengager

Down Turned Arm

Vented Riser

Direct-Connected Cyclones

FCC SUB SYSTEMS - REGENERATOR

Regenerator

Largest fluid bed combustor in commercial use Provides heat for endothermic cracking reactions Air & catalyst distribution are critical Carbon, Hydrogen & Sulphur are combusted Partial and complete combustion modes of operation Combustion air supplied by MAB through specially designed air grids Refractory lined Moves up when heated, expansion provision for connected lines, instrument taps

FCC SUB SYSTEMS - REGENERATOR

FCC SUB SYSTEMS - REGENERATOR

Regenerator

Bubbling bed (fully back mixed) 0.3 ­ 5.0 ft/sec Combustion is increased by

Oxygen partial pressure Bed temperature Catalyst pore size Improved air & catalyst distribution Smaller catalyst particle size

High combustion rates minimise unit inventory & maximise catalyst activity

FCC SUB SYSTEMS - REGENERATOR

GAS OUT

CATALYST MOVEMENT

TRANSPOORT DISENGRAGING HEIGHT

FREEBOARD

DENSE BED

GAS BUBBLE

AIR INLET

High Efficiency Regenerator

U O P's H IG H E FFIC IEN C Y R E G EN E R ATO R S YS TEM

F LUE G AS

CYCLO NES

DISENG AG ING VESSEL

CO M BUST IO N RISER

REG ENER AT ED CAT ALYST RECIRCUL AT ING CAT ALYST

CO M B UST O R

SPENT CAT ALYST

AIR

FCC SUB SYSTEMS - REFRACTORY

Refractory

To resist heat To resist erosion

Resco AA 22

A combination of the above two

Castable, gunnited refractory Vibrocast

Cold wall vs. Hot wall design Also protects against chemical corrosion Anchorage

Hex mesh `S' bars

Methods of application

FCC SUB SYSTEMS ­ AIR GRID

Air Grid

For even distribution of air in spent catalyst Proper air distribution

Lowers CRC (carbon on regenerated cat) Minimises after burn Reduces local hot spots / catalyst sintering

Mechanically robust to withstand wide range of operations / upsets Erosion, thermal expansion, mechanical integrity of supports Pressure drop across air grid

FCC SUB SYSTEMS ­ AIR GRID

Air Grid

For a typical pipe grid distributor

Nozzle exit velocity 100 ­ 200 ft/sec Pressure drop 1.5 ­ 2.0 psi Material 304 H SS, externally lined Branch arm - continuous pipe through main header

Precautions during turn around / start ups

Drain holes Covering grids during gunniting Slow introduction of air during start up

FCC SUB SYSTEMS - CYCLONES

Cyclone Separators

To separate catalyst from flue gas / hydrocarbon vapours Provided in reactor and regenerator(s) Principle of operation External / Internal Single stage / Double stage Direct coupled / Close coupled Typical inlet velocities (ft/sec)

First stage (Rx or Rg) Second stage Minimum velocity 60 ­ 70 ft/sec 80 ­ 85 ft/sec 25 ­ 35 ft/sec

Cyclones

R IS E R S T R IP P IN G B E D

R IS E R

R IS E R C Y C L O N E

'R O U G H C U T ' C Y C L O N E

P R O C E S S F L O W D IAG AM

R IS E R & R O U G H C U T C Y C L O N E S

FCC SUB SYSTEMS ­ CATALYST SYSTEM

Catalyst System Hoppers

Two / Three for fresh / spent / E cat Spent cat hopper designed for high temperature Ejector system External cyclone Cat loading to / from hoppers

FCC SUB SYSTEMS ­ CATALYST SYSTEM

Catalyst System Catalyst loader

Catalyst loading from hoppers Auto loading by diaphragm valve / auto loader For Fresh Cat / E Cat Sequence of operation Advantages

Problems with Resid Processing in FCC

Ni S V &Na

More H2, Dry Gas & Coke SOx Emission, `S' in Product Zeolite Destruction

Basic N2

Zeolite Acidity Neutralization

Aromatics

More Coke & Low conversion

Con. Coke

High Regen temp, Low Cat/Oil High catalyst consumption to maintain activity

PROCESS VARIABLES

Reactor related

Temperature Cat / Oil ratio Reaction time, Pressure

Regenerator related

CRC, Air rate and distribution Temperature, Pressure, Time Regeneration Design, Mode of regeneration

Feed Stock

Charge rate and recycle Characteristic Preheat temperature

Catalyst type and condition

PROCESS VARIABLES

Reactor Temperature

Increasing reactor temperature

Increases cat / oil Increases conversion Increases / decreases gasoline (over cracking point) Increases regenerator temperature Increases C4- yield and olefins Increases gasoline octane Increases LCO aromaticity Increases coke yield Conversion = Feed vol. ­ (LCO + HCO +CLO) vol x100 Feed vol.

PROCESS VARIABLES

GENERAL YIELD DISTRIBUTION

CONVERSION

SEVERITY

PROCESS VARIABLES

GASOLINE

SEVERITY

PROCESS VARIABLES

LPG

SEVERITY

PROCESS VARIABLES

LCO

SEVERITY

PROCESS VARIABLES

Cat / Oil ratio

Typically 5 ­10 Rapid catalyst separation prevents over cracking Increases conversion and coke levels Controlled by feed preheat, regen temperature At const Rx temp, increased cat/oil ratio will

Increase conversion Increase light gas yield Increase C3 ­ C4 yield Decrease gasoline olefin content Increase aromatic content of gasoline and LCO Increase coke yield

PROCESS VARIABLES

Reaction time

Design method of controlling severity Typically 3 ­ 6 sec in riser cracking Varies inversely with velocity A function of feed rate, pressure and temperature Higher time can result in over cracking

Reactor pressure

Normally not varied from design, effects cyclone vel. Varies with feed rate, higher pressure will Lower WGC load, increase MAB load Decrease olefin content, increase coke lay down

PROCESS VARIABLES

Carbon on regen cat

Affects catalyst activity (MAT is C free) Should be as low as reasonably possible Affected by regen temp, O2 partial pr, CSC, residence time, air distribution,

Air rate & distribution

Higher air rate, better distribution favours regeneration Pr drop across air grid 0.5 ­ 1.0 psi Higher pr drop ­ reduce air volume by increasing Rg pr Bed level may affect air distribution, cat regeneration

PROCESS VARIABLES

Regenerator design

Spent cat distribution Mixing of catalyst and air Conventionally back mix design High efficiency regenerator

Mode of operation

Partial combustion Complete combustion

PROCESS VARIABLES

Partial combustion

Requirement of CO boiler, higher steam production Operation at lower regen temperature

Less hydrothermal deactivation Less substantial metallurgy Higher CRC

Complete combustion

Reduced coke yield, higher liquid yield More stable operation Higher gasoline octane Higher olefinicity of products

PROCESS VARIABLES

Feed Characteristics

API / UOP `K'

Change may be due to boiling range and/or crude type UOP `K' = (CABP)1/3 / SG Higher API

Feed cracks more readily for same Rx temp, higher conversion At constant conversion, higher gasoline yield with lower octane Products will be less olefinic

Higher UOP'K'

More paraffinic feed Easier to crack

PROCESS VARIABLES

Feed Characteristics

Carbon residue

Indirect measure of coke producing tendency Dependent of crude source (for VGO) or feed mix (for resid) Increase in carbon residue

Increases regenerator temperature (for same crude source) Reduces cat / oil ratio Usually coupled with higher metal levels for resids

Feed preheat

An independent variable An increase in feed preheat

Reduces cat / oil ratio, reduces coke yield Reduces conversion, increases regenerator temperature

FCC CATALYSTS & ADDITIVES

FCC CATALYSTS & ADDITIVES

FCC Catalyst

Fine Porus Powder Oxides of Silica & Alumina Acid sites associated with alumina

To initiate & accelerate cracking reactions

Other elements in small amounts Acts like fluid when aerated (fluidised)

FCC CATALYSTS & ADDITIVES

Fresh Catalyst

As manufactured and supplied by manufacturer Tailor made for specific requirement

Equilibrium Catalyst (E Cat)

Catalyst used (being used) in the unit Lower activity, poor selectivity, physical changes than fresh catalyst

Flush Catalyst

Bought out E Cat for metal control

Spent Catalyst

From system From Reactor, Regenerated catalyst

FCC CATALYSTS & ADDITIVES

Zeolite Active Matrix Clay Binder

FCC CATALYSTS & ADDITIVES

Zeolite

Primary source of catalytic activity Mineral crystalline material Affects activity, selectivity, product quality Standard Y

Produced by crystallisation of sod aluminate & sod silicate Lower manufacturing cost

USY

Most widely used zeolite in FCC Higher Si / Al ratio than parent Y zeolite More resistant framework structure

Rare Earth Exchange

Na is exchanged with RE Increases zeolite activity Retards crystal destruction and dealumination in Regenerator

FCC CATALYSTS & ADDITIVES

Active Matrix

Catalytically active surface other than zeolite Has larger pores (30 ­ 500 A) than zeolite (8 ­ 9 A) Decreased bottom yields Relatively steam stable and resistant to `V' attack Ni & V can interact to form active dehydrogenation catalysts initiating high H2 & coke yields Portion of high mattrix surface area associated with small pores may not strip well and can increase regenerator coke loading

FCC CATALYSTS & ADDITIVES

Clay

Fulfills remaining catalyst particle performance requirement Serves as heat sink Serves as sink for Na

Binder

`Glue' holding all catalyst components together Provides physical integrity Some binders aid bottoms cracking

Metal Poisoning

Nickel (Ni) & Vanadium (V) deposit on outer layer of catalyst particles and catalyze dehydrogenation & condensation reactions

More Dry gas - can limit WGC capacity More Coke - can limit coke burning capacity

Higher regn. temp. Lower cat/oil ratio Loss in conversion

Ni is about four times more active than V as dehydrogenation catalyst V destroys zeolite structure resulting reduced catalyst surface area & activity

INDMAX Process

Developed by Indian Oil Corporation Ltd. 2000 bbl/day capacity demo plant commissioned in Guwahati Refinery in June'03 ­ under regular operation Currently being licensed worldwide by Lummus, USA Processing wide variety of feedstocks upto CCR of 11 wt% 4.17 MMTPA plant at Paradip refinery & 0.74 MMTPA plant at BRPL ­ expected to be commissioned in 2011

Indmax Technology- Resid to Olefins

Operational features

Very high cat/oil ratio (15-25) Higher riser temperature (>550oC) High riser steam rate

Employs proprietary catalyst comprising synergistic components ­ improved metal tolerance Benefits

LPG 35-65 wt% Propylene 17-25 wt% feed High octane gasoline (95+)

Developed & commercialized by Indian Oil

Single stage regenerator with complete combustion (CRC <0.05 wt%) without catalyst cooler upto 6 % CCR

Indmax can handle high CCR, non-hydrotreated feed with attractive LPG / light olefins yield

INDMAX at Guwahati Refinery

Successfully commissioned at Guwahati refinery in June'03 Smoothest commissioning in IOC's FCC start-up ­ being operated for maintaining refinery profitability Component DG LPG Gasoline TCO CLO Coke & loss Mixed feed CCR Gasoline RON Propylene in LPG Yields, wt% 7.4 36.2 34.7 10.5 3.5 7.5 3.75 wt% 95+ 45 wt%

Summary

FCC has been the most profitable & flexible refining process for more than 6 decades because of its ability to meet changing demands Beyond certain feed CCR, RFCC becomes too expensive due to high consumption of catalyst & inferior product yields Increasing gap in propylene demand & supply ­ can't be fulfilled by proposed steam cracker capacity Opportunity to orient FCC operation towards propylene maximization IndianOil's proven Indmax technology can meet the refiner's objectives of propylene maximization in an cost effective manner

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