Overview. Challenges in Opportunity Crude Processing 16 th April 2012

Transcription

1 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

2 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

3 What are High Acid Crudes Crudes with a TAN of 1.0 or higher O R CH 2 m C - OH n 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

4 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

5 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 used to simulate temperature and shear stress Test metallurgy of the unit Corrosion Rate, MPY Untreated Treated 4 Test inhibitor 2 effectiveness 0 CS 5Cr 9Cr 410SS Test Sample 5

6 Factors Affecting Corrosion Vulnerable HAC Locations for Preventative Other Methods Impacts 11 Examples: Vacuum Unit Severe Corrosion on an Outer Bend of an Elbow Just Upstream from the Collection Header 12 6

7 Examples: Vacuum Bubble Cap Corrosion Severe pitting Corrosion of Type 410 Stainless Bubble Cap from a Resid Stripper Column Another View of the Corroded Bubble Cap 13 Examples: 5 Cr - 1/2 Mo Check Valve in HVGO in Crude Unit 14 7

8 Factors Effecting Corrosion Temperature Naphthenic acids concentrate above 450 F (232 C) boiling range Highest concentration in F ( 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

9 Naphthenic Acid Corrosion of Carbon Steel Temperature, o C ( o F) Corrosion Rate of Carbon Steel at TAN 17 Influence of Linear Velocity on Corrosion Rates in Crude Oil Material TAN Linear Velocity, (ft/sec) Corrosion Rates at elbows (mm/yr) C.S C.S Cr-1/2Mo Cr-1/2Mo Cr-1Mo

10 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) (648) (640) (570) * Corrosion rates shown are MPY; data from literature 19 Naphthenic Acids - Distillation profile Temp (deg C) % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Volume Percent Cerro Negro (Venezuela) DOBA Grane DAR Peregrin o PetroAndina Albacora Profiles available for many crudes 20 10

11 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

12 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

13 Risk Assessment Unit / Risk System Description Asse ssm ent 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 Line from mix6 to split7 Moderate Line from split7 to furnace 101B manifold valve Moderate Manifold lines (inlets 101B) Low Example 101B Furnace of lines convective Risk area Assessment 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 CP I SCORPION Inhibitor Injection Location Corrosion Probe Monitoring Location 316SS 275 o F CS LVGO CP CS U26.1 Atmos. Resid I 5Cr 9Cr F-1 Charge Heater o F CS 316L SS 316SS 316SS 597 o F Vapor I CP 5Cr 385 o F CP CP CS F HVGO CP 5Cr CP 5Cr CS U25.1 U26.1 5Cr o F Feed Surge Drum (5Cr) 5Cr 316L SS Flash Zone 750 o F o F CP OverFlash 9Cr 9Cr Quench U o F 5Cr To DCU/Tk 434 P718 CP 5Cr 13

14 Benchmarking Nalco Scorpion Applications % of Applications > % of Applications > 4 22% of Applications > 3 33% of Applications > 2 59% of Applications > 1 85% of Applications > 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

15 How Long Does the Film Persist? C orro sion R a te a nd % HAC C r ude Corrosion Rate (mpy) C o rro sion R a te In hibito r (E C 1 245A) % H A C C r ude % HAC Crude / Inhibitor (ppm) 0 3-Mar 8-Mar 13-Mar 18-Mar 23-Mar 28-Mar 2-Apr 7-Apr 12-Apr 17-Apr 22-Apr 27-Apr 2-May 7-May 12-May 17-May 22-May 27-May 1-Jun 6-Jun 11-Jun 16-Jun 21-Jun 26-Jun 1-Jul 6-Jul 11-Jul 16-Jul 0 Date Example shown: >14 days A lot less for a transfer line Depends on velocity and turbulence Impact of Inhibitor DOBA Corrosivity Testing Corrosivity (mm/yr) Untreated Treated LVGO CUT Untreated C HVGO CUT C Treated 410SS 9 Chrome 5 Chrome Carbon Steel Carbon Steel 5 Chrom e 9 Chrom e 410SS Inhibitor Comparative Performance w/various Crudes 15

16 Naphthenic Acids other impacts Impact on Tank Farm Poor water removal Emulsion formation in tankage Tank Farm Solutions Tank mixers Crude blending Tankage dehydration additives Impact on Desalter Emulsion in desalter Oil undercarry Water carryover Desalter Solutions Increase wash water Increase temperature Increase mixing Demulsifier selection 31 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 16

17 SCORPION High Temperature Corrosion Control 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 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 Protecting Your Plant and Profits 34 Thank you 17