1 Challenges in Opportunity Crude Processing 16 th April 2012 Thomas Lu Industry 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 1
Opportunity Crude Trends • Extra Heavy (< 22 o API) as part of crude slates (average globally) • Declining conventional oil production • Opportunity crude oil production forecast to grow up to 20% by 2025 Fundamentals Historic Perspective Problem 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 4 2
What are High Acid Crudes Crudes with a TAN of 1.0 or higher O R CH C - OH 2 n m R = Alkyl Groups COOH = Carboxylic Acid CH 2 = Alkyl chain 5 Fundamentals Measurement TAN = 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 6 3
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. High Temperature Naphthenic Acid Corrosion Not all TAN is a problem Measure of naphthenic acid content better gauge of corrosivity 4
Distribution of Acid 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 Corrosivity Testing Laboratory apparatus Untreated 18 used to simulate 16 temperature and Treated 14 shear stress Corrosion Rate, MPY 12 10 Test metallurgy of the 8 unit 6 4 Test inhibitor 2 effectiveness 0 C S 5Cr 9C r 410SS Test Sample 5
Factors Affecting Corrosion Vulnerable Locations for HAC Preventative Methods Other Impacts 11 Examples: Vacuum Unit Severe Corrosion on an Outer Bend of an Elbow Just Upstream from the Collection Header 12 6
Examples: Vacuum Bubble Cap Corrosion Severe pitting Corrosion of Type 410 Another View of the Corroded Bubble Stainless Bubble Cap from a Resid Cap Stripper Column 13 Examples: 5 Cr - 1/2 Mo Check Valve in HVGO in Crude Unit 14 7
Factors Effecting Corrosion Temperature Naphthenic 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 15 Factors Effecting Corrosion cont. Velocity At low velocity, turbulence caused by boiling and condensing causes attack At high velocity, rapid corrosion can occur Limits well defined for “ conventional ” crudes 16 8
Naphthenic Acid Corrosion of Carbon Steel 40 30 20 10 0 150 200 200 250 250 300 300 350 350 302 390 480 570 660 Temperature, o C ( o F) Corrosion Rate of Carbon Steel at 1.8 - 2.4 TAN 17 Influence of Linear Velocity on Corrosion Rates in Crude Oil Material TAN Linear Velocity, Corrosion Rates (ft/sec) 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 18 9
Corrosion Rates of Some Alloy Steels During 7 Month Coupon Exposure in a Crude Unit Temperature Acid No. C.S. 410SS 304SS 316SS o C ( o F) 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 19 Naphthenic Acids - Distillation profile 8 0 0 7 0 0 6 0 0 5 0 0 Temp (deg C) 4 0 0 C e rro Ne g ro (Ve n e z u e la ) 3 0 0 D O B A G ra n e 2 0 0 D A R P e re g rin o 1 0 0 P e tro A n d in a A lb a c o ra 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 Profiles available for many crudes 20 10
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 21 Prevention Methods cont Use of Inhibitors Continuous 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 22 11
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 12
Risk Assessment Unit / Risk System Description Assessment Line from mix5 to split6 Moderate Line from split6 to furnace 302B control valve 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 &101B Line from mix6 to split7 Moderate Line from split7 to furnace 101B manifold valve Moderate Example of Risk Assessment Example of Risk Assessment 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 High Acid Crude Assessment Output Fuel Gas/Distillate to Vacuum System 316SS 275 o F CS SCORPION Inhibitor U26.1 I LVGO Injection Location CP CS Corrosion Probe CP Monitoring Location F-1 Charge 385 o F Heater CP CP 5Cr 316SS I CS CP 545-565 ° F Atmos. CS 597 o F CS U26.1 Resid Vapor CP U25.1 HVGO 5Cr 9Cr 5Cr I 316L CP 316SS o F 750-760 SS 5Cr 5Cr Feed 650-700 o F Surge 316L SS Drum 625-650 o F CP 5Cr (5Cr) OverFlash Flash Zone 9Cr 750 o F 9Cr Quench U25.1 600-650 o F 5Cr To DCU/Tk 434 P718 CP 5Cr 13
Benchmarking Nalco Scorpion Applications 8 7 1% of Applications > 6 6 5 3% of Applications > 4 4 22% of Applications > 3 3 33% of Applications > 2 2 59% of Applications > 1 1 85% of Applications > 0.5 0 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 Nalco Phosphorous-based Sulphur-based Phosphorous and Sulphur based Nalco possessed patents on Phosphate ester chemistry, and possesses patents on Sulphur and combination chemistries. 14
How Long Does the Film Persist? C o r r o s i o n R a t e a n d % H A C C r u d e 1 0 6 0 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 ) 9 % H A C C r u d e 5 0 % HAC Crude / Inhibitor (ppm) 8 Corrosion Rate (mpy) 7 4 0 6 5 3 0 4 2 0 3 2 1 0 1 0 0 r r r r r r r y y y y y y n n n n n n l l l l a a a a a a p r p p r p r p r p r a a a a a a u u u u u u u u u u M M M M M M A A A A A A M M M M M M J J J J J J J J - J J - - - - - - - - - - - - - - - - - - - - - - - 1 - 6 - 1 6 3 8 3 8 3 8 2 7 2 7 2 7 2 7 2 7 - 2 7 - 1 6 1 6 1 6 1 1 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 D a t e Example shown: >14 days A lot less for a transfer line Depends on velocity and turbulence Impact of Inhibitor D O B A C o rro sivity T estin g 1.0 0.9 0.8 4 1 0 S S Corrosivity (mm/yr) 0.7 9 C h ro m e 0.6 5 C h ro m e C a rb o n S te e l 0.5 0.4 0.3 0.2 C a r b o n S te e l 0.1 5 Chrom e 0.0 9 Chrom e U n tre a te d 4 1 0 S S T r e a te d LVG O C U T U n tre a te d 370-425 C T r e a te d H VG O C U T 510-555 C Inhibitor Comparative Performance w/Various Crudes 15
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