Baker

© 2007 Baker Hughes Incorporated. All Rights Reserved.

New Technology Controls High Temperature Coker

Heater Fouling

AIChE Chicago Symposium 2007September 25, 2007

Presented by:Bruce Wright



Discussion Topics

1. Coker economics and impact of fouling on DCU and refinery operations

2. Coker heater fouling mechanisms3. Stages of fouling4. Design of custom MILESTONETM additive

programs 5. Coking Stability Index (CSI)6. Case histories7. Summary

MILESTONE is a trademark of Baker Hughes Incorporated


Delayed Coker Economics• Coker Economic “Drivers”

– Primary driver is the differential value of light distillates (gasoline, kerosene, diesel) versus heavy fuel oils

Product Prices: 1998-2005

01020304050607080

Avg1998

Avg1999

Avg2000

Avg2001

Avg2002

Avg2003

A vg2004

Avg2005

$/B

bl

Reg Gaso HS Dist Resid Fuel

US Gulf Coast (Hart’s Downstream Energy Services)


Delayed Coker EconomicsGlobal market conditions have caused a great

increase in coker margins since 2003:C a lc u la te d C o k in g M a r g in

0

2

4

6

8

1 0

1 2

1 4

1 6

1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5

$/B

bl

Cokers are making a lot of money, and refiners want new ways to increase unit throughput!

US Gulf Coast (Hart’s Downstream Energy Services)

Economic Impacts of Coker Heater Fouling

Throughput Losses

Conversion Losses

Increased Fuel Usage

De-coking Costs

Reduced Flexibility

E, H & S Concerns

2-5% ~ $5 MM

$25 – 50 M/coil

Can be > $5 MM

1% ~ $3 MM

2% > $200,000

(All Values Based on Typical 40,000 B/D Unit)


Coker Heater Design & Operation• Operating Parameters Affecting Coking RatesØFluid velocity

ØContinuous throughput

Continuous Flow and Adequate Velocities are Critical to Good Operations!

Coker Heater Design & Operation• Operating Parameters Affecting Coking RateØHeater Outlet Temperatures

ØUneven Heat Distribution - “Hot Spots”

ØPoor Flow Distribution

732

704

677

510

593

621

649

538

568

°C


Feed Factors Impacting Fouling

• Asphaltene content and stability Ø Higher asphaltene content leads to more

coke generation in the coilsØ Low stability feeds result in increased

fouling

• Content of solids/inorganics Ø Corrosion by-productsØ Filterable solids and saltsØ Sodium concentration

Sources of Inorganic Materials• Iron sulfide, rust (corrosion by-products)ØCrude oil storage and transmissionØUpstream process units

• Salts: sodium, calcium, and magnesium chlorides ØFrom crude oil producing formationØBrine contamination from transportation

• CausticØNaOH injections into desalted crude

• Clay, dirt, sand, catalyst finesØFrom producing formation or bitumen depositØFrom upstream process units


Resins

Asphaltene Core

Asphaltene Micelle In Solution


Asphaltene Destabilization• Asphaltenes readily destabilize when subjected to

stressØ Changes in pressure, temperature, pH and solution

environment can cause destabilization

Ø Can occur when oils are blended and processed

• Disruption of asphaltene – resin interaction

• Thermal cracking conditions (>750°F) cause progressive loss of asphaltene solubility in the bulk oil phase

• Asphaltenes lose paraffinic side-chains and naphthenic portions are de-hydrogenated to aromatic rings

Thermal Decomposition of Oil• Concentration of paraffin compounds increases• Resins are lost from conversion to asphaltenes • Naphthenes become aromatic• Aromatics condense to form asphaltenes – lose

solubility in bulk oil

+Heat

HSolubility Loss,

Precipitation, De-hydrogenation, Coke Formation

HeatN-


Coke Formation• High temperature destabilizes asphaltenes -

They become more aromatic and less soluble in the bulk liquid

• Destabilized asphaltenes aggregate to become particle-like

• The agglomerated phase precipitates, adheres to the hot tube surfaces and de-hydrogenates to form coke

• At the unit start-up cleaned coils have a catalytic effect on asphaltene deposition

Asphaltene Precipitation

Asphaltene Destabilization

Hot Tube Surface

Deposition

Degradation

Aggregation

Stress & Disruption

of Resins


Stages of Fouling

• Initial layer formed on tube surfaceØMetal catalyzed cokingØFast - at the startup of the unit when coils

are clean and metal is exposed

• Secondary layer of depositionØDecreased asphaltene solubility in bulk oilØThermal breakdown of asphaltenesØPrecipitation of thermally converted

asphaltenes or coke ØSlower


Catalysis of Coke Formation• Initial rapid coking due to

tube surface metals– Cu >> Ni ~ Cr > Fe, but…– Many Fe sites available– The activation energy

needed to crack and de-hydrogenate is decreased

• Continued catalytic effects from metals cracked out of resid – Contributes to steady

state coking of the furnace tubes

Stages of Fouling

InitialInitial T imeTime Shutdow nShutdow n

InitialInitialFoulingFouling

S teady State FoulingS teady State Fouling B u lk FoulingBulk Fouling

Hea

t Tra

nsfe

rH

eat T

rans

fer

Coe

ffic

ient

C

oeff

icie

nt ““

UU””

Pres

sure

Dro

pPr

essu

re D

rop


Stages of Fouling – Heater Tubes

1000

1050

1100

1150

1200

1250

0 10 20 30 40 50 60 70 80 90 100

Days on Line

Skin

Tem

pera

ture

(F)

Slope for first 30 days is 3.9 degrees F / day

Slope for day 31 until end is 1.3 degrees F / day

With Successful Treatment

Delayed Coker Heater Skin Temperatures


Fouling Control Additives

Program Success

RequirementsDisperse

Inorganic & Organic Particles

Polar functionality to adsorb on active metal

sites

Withstand High

Temperatures

Stabilize Asphaltenes


Research Program Design

• Feedstock characterization test protocols

• Deposit characterizations

• Property ratios, correlations with fouling tendency

• Development of the Coking Stability Index

• Benchmark fluid characteristics with others in data base


Coking Stability Index (CSI)

• Predictive tool for determining fouling potential and rate of fouling

• Uses an NIR laser to detect the onset of asphaltene precipitation

• Titration technique with non-solvent• Used in conjunction with oil

characterizations to determine stability of coker feed

• Chemical additive screening

2.940.458192.09.0 MonthsWest Coast

3.850.325137.15.0 monthsMidwest

2.630.34899.52.4 MonthsCanadian

Saturate/AromaticRatio

Asphaltene/ResinRatio

CSIFurnaceRun Length

Coker Feed

CSI Coker Stability IndexFurnace Feed Stability

0

200

400

600

800

1000

1200

0 50 100 150 200 250 300

CSI

INT

EN

SIT

Y

West Coast RefinerMidwest Refiner Furnace FeedCanadian Refiner Furnace Feed

More Stable


MILESTONE Heater Fouling Control

Advanced Process Heater Fouling Control Technology

• A new fouling control program developed for high

severity thermal conversion unit heaters

• Involves proprietary testing to understand the fouling mechanisms, and chemical program effectiveness

• Novel, multi-component fouling control solutions– Custom designed based on feedstock characterizations and

comprehensive root cause investigations

– Specialized feedstock characterization methodologies

– Utilizes new high temperature chemistries

MILESTONE Additive Technology Multi-Component Program

• Interacts with metal surfaces to reduce catalytic effects on surface coking reactions

• Stabilizes asphaltenic compounds in the feedstock to inhibit their precipitation

• Disperses organic & inorganic particles


JIP – Joint Industry Project, Using Department of Energy (DOE) Pilot Delayed Coking Unit

at the University of Tulsa, OKØ Investment by major refiners to study coker

operating variables, including coker heater fouling

Ø Pilot unit studies confirmed suspected heater fouling mechanisms

Ø Pilot unit tests also confirmed efficacy of Baker Petrolite fouling control technology

MILESTONE Technology:Pilot Scale Demonstrations


Case History Summary

RefineryReduction in Fouling Rate

Throughput Improvement

Return on Program

A 9X 5% >6:1

B 3X Returned to Normal

>3:1

C 20% >10:1

MILESTONE Program Performance


Summary• Delayed coker furnace fouling is a

complex phenomenon involving heavy hydrocarbon compounds and inorganic materials

• Two stages of fouling: initial catalytic stage and thermal or steady-state stage

• Costs of delayed coker furnace fouling can be significant especially when throughput is restricted either during operation or during de-coking cycles


Summary• The Baker Petrolite research group has

developed a successful mitigation program for delayed coker furnace fouling

• A new, multi-component program is utilized to combat the various mechanisms of heater fouling

• Treatment programs have been used in several applications with significant economic benefits


Thank You for Your Attention!

Baker

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