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Challenges in Opportunity Crude Processing

16th April 2012

Thomas LuIndustry Development Manager Asia Pacific

Overview

• Opportunity Crude Trends (High TAN Crude) and its challenges

• Overview of Factors Affecting Corrosion

• Prevention Methods

• High Temperature Corrosion Control

• Summary

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Opportunity Crude Trends

• Declining conventional oil production

• Opportunity crude oil production forecast to grow up to 20% by 2025

• Extra Heavy (< 22o API) as part of crude slates (average globally)

Fundamentals

Historic PerspectiveProblem since 1920s

Systematic study since 1950s

Chevron published correlation in 1980s

Nalco first Scorpion program in 1984

Nalco published Sulfidic corrosion phenomenon in 2005

Review of 25 years of Scorpion program published in 2006

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3

What are High Acid Crudes

Crudes with a TAN of 1.0 or higher

5

R CH2

m

C - OH

n

O

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

Fundamentals

MeasurementTAN = Total Acid Number

Two common ASTM methods:- D974 (colorimetric- older, used for distillates)

- D664 (potentiometric- more accurate but measures acid gases, in addition to organic acids)

- Differences important on crudes, less significant on distillates)

UOP 565 / UOP 587 more applicable

Nalco NAT

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Will it Cause Corrosion?

Majority of the challenge crudes on the market are high acid crudes Total acidity

Naphthenic acid content

Distribution of acids

Other species include organic acids, organic chlorides, undesaltable chlorides, amines, etc.

Not all TAN is a problem

Measure of naphthenic acid content better gauge of corrosivity

High Temperature Naphthenic Acid Corrosion

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Distribution can be used to determine likely areas of concern Some newer assays have this TAN data Nalco has a library of high acid crude nap acid

distributions

- Relative comparison with respect to field experience

Distribution of Acid

Corrosivity Testing

Laboratory apparatus used to simulate temperature and shear stress

Test metallurgy of the unit

Test inhibitor effectiveness 0

2

4

6

8

10

12

14

16

18

Co

rro

sio

n R

ate

, M

PY

CS 5Cr 9Cr 410SS

Test Sample

Untreated

Treated

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Factors Affecting Corrosion

Vulnerable Locations for HAC

Preventative Methods

Other Impacts

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Examples: Vacuum Unit

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Severe Corrosion on an Outer Bend of an Elbow Just Upstream from the Collection Header

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Examples: Vacuum Bubble Cap Corrosion

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Severe pitting Corrosion of Type 410Stainless Bubble Cap from a Resid Stripper Column

Another View of the Corroded Bubble Cap

Examples: 5 Cr - 1/2 Mo Check Valve in HVGO in Crude Unit

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Factors Effecting Corrosion

TemperatureNaphthenic acids concentrate above 450°F (232°C)

boiling range

Highest concentration in 600-800°F (316-427°C) boiling range

Lowest temperature where attack occurs ~400°F (200°C)

Lower molecular acids at water condensing locations: HCOOH ; (CH3)n-COOH

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Factors Effecting Corrosion cont.

VelocityAt low velocity, turbulence caused by boiling and condensing causes attack

At high velocity, rapid corrosion can occur

Limits well defined for “conventional” crudes

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9

Naphthenic Acid Corrosion of Carbon Steel

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150302

200 250 300 3500

10

20

30

40

200390

250480

300570

350660

Temperature, oC (o F)

Corrosion Rate of Carbon Steel at 1.8 - 2.4 TAN

Influence of Linear Velocity on Corrosion Rates in Crude Oil

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Material TAN Linear Velocity,(ft/sec)

Corrosion Rates at elbows (mm/yr)

C.S. 1.5 73 12

C.S. 1.5 26 6

5Cr-1/2Mo 1.5 73 2

5Cr-1/2Mo 1.5 26 0.6

9Cr-1Mo 1.5 73 0.7

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Corrosion Rates of Some Alloy Steels During 7 Month Coupon Exposure in a Crude Unit

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TemperatureoC (oF)

Acid No. C.S. 410SS 304SS 316SS

377 (710) 3+ 48+ 22 0.09 0.06

342 (648) 3.6 49+ 0.5 33 0.08

338 (640) 3.6 48+ 30 30 4.8

300 (570) 4.1 37 5.8 10 0.01

* Corrosion rates shown are MPY; data from literature

Naphthenic Acids - Distillation profile

20Profiles available for many crudes

0

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

6 0 0

7 0 0

8 0 0

0 % 1 0 % 2 0 % 3 0 % 4 0 % 5 0 % 6 0 % 7 0 % 8 0 % 9 0 % 1 0 0 %

V o lu m e P e r c e n t

Te

mp

(d

eg

C)

C e rro N e g ro (V e n e z u e la )

D O B A

G ra n e

D A R

P e re g rin o

P e tro A n d in a

A lb a c o ra

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Prevention Methods

Blending Typically , blend high TAN with low TAN crude

Blending primarily based on desired product mix

Metallurgy can become limiting

Crude compatibility needs evaluation

Sulfur in blend crude may be critical

Materials Upgrade In mild service, 9 Cr - 1 Mo sometimes adequate

Usually 316L (2% Mo) minimum material

317L (3% Mo) often used

Structured packing requires 317L min.

When chloride stress corrosion cracking (CISCC) is a potential problem, 2205 or 2507 have been used

When high corrosion and/or CISCC are a problem, I625 has been used

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Prevention Methods cont

Use of InhibitorsContinuous use of high acid crudes (HAC)

- Successful applications exist for wide range of TAN and NAT

- Important to maintain monitoring in areas at risk

- Can be continuous or (depending upon strategy) until metallurgy is upgraded.

Intermittent use of HAC- Used when corrosion rates are excessive based on monitoring

Cost directly related to amount of equipment protected

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High Temperature Corrosion Control

SCORPION High Temperature

Corrosion Control

• 25+ Years of Experience

• >130 HAC Assessments Globally

• Innovative Monitoring (FSM)

• Most Comprehensive Chemistries

Best Practice in KM (KM, Downstream, Our Brands, click on SCORPION logo)

Step 1. Assessment

Risk Assessment

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Unit / Risk

System Description Assessment

Line from mix5 to split6 Moderate

Line from split6 to furnace 302B control va lve manifold. Low

Crude to Furnace control valve Low

Furnace lines Moderate

Line from furnace colector to mix 6 High

Line from split6 to mix6 (by-pass) Low

Furn.302B to Furn.151B &101BLine from mix6 to split7 Moderate

Line from split7 to furnace 101B manifold valve Moderate

Manifold lines (inlets 101B) Low

101B Furnace lines convective area Moderate

101B Furnace lines radiation area Moderate

Lines from furnace 101B colector to mix7.1 Low

Line from mix7.1 to mix7 Low

Line from split7 to furnace 151B manifold valve Moderate

Manifold lines (inlets 151B) Moderate

151B Furnace lines convective area Moderate

151B Furnace lines radiation area Low

Lines from furnace 151B colector to mix7.2 High

Line from mix7.2 to mix7 High

Example of Risk AssessmentExample of Risk Assessment

Risk Assessment

High Acid Crude Assessment Output

SCORPION Inhibitor Injection Location

Corrosion Probe Monitoring LocationCP

I

P718

To DCU/Tk 434

U26.1LVGO

316SS

316SS

316SS

HVGO

CS

5Cr

545-565°F

385oF

597oFVapor

I

CS

CS

OverFlash

650-700oF

9Cr

5Cr

600-650oF

Quench

Flash Zone750oF

750-760oF

316L SS

I

FeedSurgeDrum(5Cr)

625-650oF5Cr

5Cr

Atmos.Resid

9Cr

5Cr

CS

316LSS

5Cr

9Cr

F-1 ChargeHeater

Fuel Gas/Distillateto Vacuum System

275oF

CSU26.1

U25.1

5Cr

U25.1

CP

CP

CP

5CrCP

CP

CP

CP

CP

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Benchmarking Nalco Scorpion Applications

0

1

2

3

4

5

6

7

8

1% of Applications > 6

3% of Applications > 4

22% of Applications > 3

33% of Applications > 2

59% of Applications > 1

85% of Applications > 0.5

How Does SCORPION Work?

Inhibitors work by forming an extremely tenacious and persistent passive surface

Currently there are three types of SCORPION inhibitors supplied by NalcoPhosphorous-based

Sulphur-based

Phosphorous and Sulphur based

Nalco possessed patents on Phosphate ester chemistry, and possesses patents on Sulphur and combination chemistries.

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How Long Does the Film Persist?

Example shown: >14 days

A lot less for a transfer line

Depends on velocity and turbulence

C o r r o s i o n R a t e a n d % H A C C r u d e

0

1

2

3

4

5

6

7

8

9

1 0

3-M

ar

8-M

ar

13-M

ar

18-M

ar

23-M

ar

28-M

ar

2-Apr

7-Apr

12-A

pr

17-A

pr

22-A

pr

27-A

pr

2-M

ay

7-M

ay

12-M

ay

17-M

ay

22-M

ay

27-M

ay

1-Ju

n

6-Ju

n

11-J

un

16-J

un

21-J

un

26-J

un1-

Jul

6-Ju

l

11-J

ul

16-J

ul

D a t e

Co

rro

sio

n R

ate

(m

py

)

0

1 0

2 0

3 0

4 0

5 0

6 0

% H

AC

Cru

de

/ In

hib

ito

r (p

pm

)

C o r r o s i o n R a t e I n h i b i t o r ( E C 1 2 4 5 A )

% H A C C r u d e

Impact of Inhibitor

U n tre a te dT r e a te d

U n tre a te dT r e a te d

4 1 0 S S

9 Chrom e

5 Chrom e

C a r b o n S te e l

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Co

rro

siv

ity (

mm

/yr)

D O B A C o rro sivi ty T est in g

4 1 0 S S

9 C h ro m e

5 C h ro m e

C a rb o n S te e l

LVG O C U T

370-425 C H VG O C U T

510-555 CInhibitor Comparative Performance w/Various Crudes

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Naphthenic Acids other impacts

Impact on Tank FarmPoor water removal

Emulsion formation in tankage

Impact on DesalterEmulsion in desalter

Oil undercarry

Water carryover

Tank Farm SolutionsTank mixers

Crude blending

Tankage dehydration additives

Desalter Solutions Increase wash water

Increase temperature

Increase mixing

Demulsifier selection

Summary

Processing opportunity crudes (e.g. High TAN) can significantly improve refinery profitability, often offer >US$10/bbl discounts

Testing can be done before the crude arrives to identify potential risks in desalting, fouling, corrosion, and waste plant

Communication between buyers, refiners and crude process aid suppliers is key to successful introduction

Planning ahead can allow the refiner to reduce unknown risks associated with running Challenge/Opportunity Crudes

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SCORPION High Temperature Corrosion Control

Protecting Your Plant and Profits

Crude Challenge – Low TAN, High Sulfur

SCORPION High Temperature Corrosion Control• Proven effective against Sulfidic attack in the lab

• Proven effective against Sulfidic attack in the field 2008 - present

EuroCorr 2007 paper, Hydrocarbon Engineering article, September 2008;• Chemical Inhibition of High Temperature Sulphidic Corrosion in Lab Evaluations

and Petroleum Refinery Applications, C. Claesen, S. A. Lordo, G. Scattergood

2008 paper, March 2009 article in Hydrocarbon Engineering• Chemical Inhibition of Sulfidic Corrosion at Chinese Refinery, V. Chua, G.

Scattergood

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Thank you