Naphthenic Acid Bearing Refinery Feedstocks

Nalco Company Proprietary Knowledge

Naphthenic Acid Bearing Refinery Feedstocks and

Corrosion Abatement

October 2006AIChE - Chicago Symposium 2006

Presenter: Dennis Haynes


High Acid Crude Balance

High Acid Crude Supply > 1.0 TAN

0100020003000400050006000700080009000

10000

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

mbd

Far EastWAFRAmericasNorthwest Europe

% of Total Forecast Global Crude Supply

7.00%

7.50%

8.00%

8.50%

9.00%

9.50%

10.00%

10.50%

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010


The Processing Puzzle

PredictingCorrosivity

All aspects of the puzzle must be

properly evaluated and fitted together

in order to maximise profits

Experience is ABSOLUTELY critical

No relearning needed – with associated risk

CrudeProperties

ReliabilityImpact

MitigationMonitoring &

Inspection

Economics


What are High Acid Crudes

• Crudes with a TAN of 1.0 or higher

R CH2m

C - OHn

O

R = Alkyl Groups COOH = Carboxylic Acid CH2 = Alkyl chain


Fundamentals

• MeasurementTAN = Total Acid NumberTwo common ASTM methods:

D947 (colorimetric- older, used for distillates)D664 (potentiometric- more accurate but measures acid gases and hydrolyzable salts in addition to organic acids)Differences important on crudes, less significant on distillates

Nalco NAT testing is more precise for quantifying Naphthenic Acid content


Naphthenic Acid Distribution


Fundamentals

• Factors Effecting CorrosionTemperature

Naphthenic acids concentrate above 260 °C boiling rangeHighest concentration in 316-427°C boiling rangeLowest temperature where attack occurs ~200°C (400oF)Above 450°C (825oF) disintegrates into lower molecular acids


Fundamentals

• Factors Effecting Corrosion cont.Velocity / Turbulence

At low velocity, acid concentration caused by boiling and condensing causes attackAt high velocity, multiphase stream rapid corrosion can occur due to erosion-corrosionTurbulence / cavitation in pumps may result in rapid attack

Other SpeciesSulfur Species

– Naphthenic Acid based corrosion is either reduced or augmented depending on:

» Wt. % sulfur» Amount of “reactive” (lighter) sulfur species present» Whether NAT is high or low» Whether phase is liquid or vapor


Typical Areas of Corrosion

Affected Areas


Corrosion Examples


Corrosion Examples


Prevention Methods


Prevention Methods

• BlendingDoesn’t take advantage of full possible profits

• Metallurgical UpgradesEconomical if small in scope or continuous supply and processing is planned

• InhibitorsIntermittent use of HACContinuous use of High Acid Crudes (HAC)


How Does SCORPION® II Work?

• Inhibitors work by forming an extremely tenacious and persistent passive surface

• Currently there are three types of SCORPION II inhibitors supplied by Nalco

Phosphorous-basedSulphur-basedPhosphorous and Sulphur based


Nalco’s Experience

• Nalco is the recognized Industry leader in chemically controlling HAC Corrosion worldwide

• Currently treat approximately 90% of all the systems requiring control

• Nalco was the first to bring to Industry a chemical solution to HAC corrosion in 1982

• Total units (Crude: APS+VPS and others) treated during that time has been >60

• Current active application count is 37 out of 46 units

• Nalco treats units in 4 out of the top 7 world’s largest REFINERS


SCORPION II Corrosion Inhibitors

• Applied toFurnacesTransfer linesPump-around circuitsProduct Side Draws

• Application PointVia suitable injection system designUpstream of anticipated area of risk


Typical Injection Locations


Corrosion Inhibitor Performance 3rd Party Laboratory Evaluations

• Asian AGO Sample• TAN = 3.8• P/S Based Chemistry• Test Temperature

260oC (500oF)• CS 90 % Inhibition• 5Cr 91 % Inhibition• 9Cr 82 % Inhibition• 410SS 96% Inhibition

0

2

4

6

8

10

12

14

16

18

Corr

osion Ra

te, MPY

CS 5Cr 9Cr 410SS

Test Sample

Treated

UnTreated


Some Crudes Treated

• Captain• Alba• Heidrun• Harding• Doba• Lokele• Kuito• Marlim• Zafiro• Hungo• SJV• Leadon

• Topacio• Oguendjo• Grane• Balder• Merey• Ecsalante• Canadon Seco• Troll• Gryphon• Escravos• Vasconia


MONITORING


Inspection & Monitoring

• Monitoring TechniquesNo single monitoring technique will sufficeRetractable couponsElectric resistance probesFlush ERPField Signature Method (FSM) Technology Corrosion monitoring loopUT/RadiographyMetals Analysis


Field Signature Method (FSM)

• FSM is a non-intrusive corrosion monitoring method that has some particular advantages for Naphthenic Acid monitoring.

• Corrosion measurements are made on the actual process component, as opposed to using a probe that measures the corrosivity of the process.


FSM-IT Plot

Flow


FSM-IT Used to Adjust Treatment

Increased SCORPION Dosage


CASE HISTORY


Background

• Refinery increased High TAN crude slate to 30 - 40% of total feed from previous 10 - 15%

• Discounted > $1 BBL over crude with similar yield pattern (low TAN)

• Based on 80kbpd, Goal was to Process extra 20% of High TAN crude while maintaining specified Corrosion Rates

• Equivalent to 16 kbpd ; $16k/Day or $5.8M/yr


Background

• Range of feed TAN : 0.9 - 1.8• Nalco Phosphorous-based inhibitor• Dosage dependent upon feed TAN,

ranging from 5 - 15 ppm. In use for over 4 years.

• 15 - 20% of HGO passes to Unocal hydrocracker process - no problems with P in feed


Kero to Stripper

Metallurgy : 5Cr + Carbon Steel

200oC

520oF

700oF

326oF

Light Gas Oil

WaterTo Splitter

Heavy gas Oil

662oF

Corrosion Rates (mpy)Before After % Inhibition

BPA 60 3 95HGO 51 2 96Transfer 130 5 96

400oF

BPA

TPA

MPA

Feed


Summary

• Naphthenic acid crudes can be processed safely and profitably

• Key success factor is to act proactively as much as possible – MANAGE THE RISK

Fully survey the systemImplement full monitoring programHave correct injection facilities available in case requiredContinually review results and implement changes as necessary

• SCORPION II Programs are fully proven - NO FAILURES

• Inhibitors are a cost effective means to increase high acid crude processing


Further Reading

• Skippins, J., Johnson, D., Davies, R., “Corrosion mitigation program improves economics for processing naphthenic crudes”, Oil & Gas Journal, September 11, 2000.

• Mathers, R., David, P., Kettle, A., Jones, P., “Management and mitigation of the issues associated with processing High Acid Crudes using a chemistry based approach with a focus on Doba processing at ChevronTexaco Pembroke”, High TAN Crude Conference, Singapore, May 2005.

• Johnson, D., McAteer, G., Zuk, H., “Mitigating Corrosion from Naphthenic Acid Streams”, Petroleum and Technology Quarterly, Winter 2003.

• Babaian-Kibala, E., Craig Jr., H.L., Rusk, G.L., Blanchard, K.V., Rose, T.J., Uehlein, B.L., Quinter, R.C., Summers, M.A., “Naphthenic Acid Corrosion in a Refinery Setting”, CORROSION/93, Paper No. 631.

• Craig Jr., H.L., “Naphthenic Acid Corrosion in Crude Distillation Units”, CORROSION/87, Paper No. 196.

• Haynes, D., “Opportunities for Asia Pacific Refiners in processing High TAN Crude Feedstocks”, ARTC 2003.

• Gutzeit, J., “Naphthenic Acid Corrosion in Oil Refineries”, Materials Performance, 16 (10), 24-35, October 1977.

• Craig Jr., H.L., “Naphthenic Acid Corrosion in the Refinery”, CORROSION/95, Paper No. 333.

Documents

Naphthenic Acid Bearing Refinery Feedstocks