Real Time Oil Corrosivity Measurement Using Radioactive

Real Time Oil Corrosivity MeasurementUsing

Radioactive Tracer Technology

Southwest Research InstituteSan Antonio, TX

Douglas C. EberleSenior Research Engineer

Filtration and Fine Particle Technology, San Antonio, TX(210)522-5260

[email protected]

Southwest Research Institute

1,200 Acres

2M square feet ofLaboratories and Offices

2,700 Employees

$340M Revenue in FY02

11 Technical Divisions

1/3 Dedicated toAutomotive R&D

Overview

SwRI Has Used Internal Funds to Developa Unique Method to Measure CorrosivityUsing Radioactive Tracer TechnologyHighly Sensitive Time ResolvedCorrosivity Measurement Under SimulatedRefinery Conditions to Measure the TrueCorrosivity of an Oil Sample

Background

Crude Oil Corrosivity TypicallyPredicted Through ProprietaryCorrelation Models Involving TAN, %Sor Other ParametersWell Known That These Models AreExpensive to Develop, Are Not Reliableand Can Be Very Misleading

Background (cont.)Corrosivity vs. TAN and %S From

SwRI TestsCorrosion Rate vs. Total Acid Number (TAN)

0

10

20

30

40

50

60

0 2 4 6 8

TAN (mg KOH/g)

Cor

rosi

on R

ate

(mils

/yea

r)

Corrosion Rate vs % Sulfur

0

10

20

30

40

50

60

0 1 2 3 4

% Sulfur

Cor

rosi

on R

ate

(mils

/yea

r)

Background (cont.)

Corrosivity Typically Measured UsingMass Loss Coupons in an AutoclaveMass Loss Measurement Proven to beUnreliable

Likely Significant Changes in Oil Corrosivity Over LengthyTest (24 hrs or longer) due to Thermal Degradation ofNaphthenic AcidRequires Subtraction of Two Relatively Large Numbers(Before and After Coupon Mass) to Measure RelativelySmall Mass, Resulting in InaccuraciesCan Actually Show Weight Gain

Radioactive Tracer Technology(RATT)

SwRI Has Been Using Radioactive TracerTechnology (RATT) for Over 40 YearsPrincipally Used at SwRI for MeasuringReal Time Wear In Internal CombustionEnginesProven to be Highly Sensitive Time-Resolved Wear Measurement Technique

Sample Engine Wear Data

RATT Method-General Overview

Activate Corrosion Coupons In NuclearReactor (Thermal Neutron Activation)

Conversion of Stable Fe-58 Isotope to Radioactive Fe-59Fe-59 Emits Detectable Gamma Rays at 1099 and 1292 keVHalf-life of 44.6 days

Calibrate Coupon Activity to CorrelateMeasured Corrosion Product Activity inOil to Coupon Mass LossInstall Corrosion Coupon in Flow Loopand Run at Simulated RefineryConditions

Simplified System Schematic

Corrosion Coupon

Gamma RayDetector

Lead Shield

Pump

Pressure Gauge

Corrosivity Test Setup

Sample Gamma Spectrum

RATT Method (cont.)

Monitor Oil in Real-time (at 10-minuteIncrements) for Accumulation ofRadioactive Corrosion ProductsRelate Measured Radioactivity toCumulative Corrosion Product MassDifferentiate Cumulative Corrosion Massto Obtain Corrosion Rate

Features and Benefits

Time Resolved Corrosivity DataTypically 10-minute ResolutionShows Features Unable To Obtain With Weight LossAbility to Capture Initial and Longer Term Corrosion Rates

Short Term TestTotal Test Time Typically 5 hoursOil Properties Less Likely to Change Significantly inShorter Term

Features and Benefits(cont.)

Recirculating Flow LoopAbility to Tailor Tests for Specific Conditions

AccurateRepeatableHighly Sensitive

Sampling of Test Results from IR Project

Test OilTAN

(mgKOH/g)

Sulfur(%)

MeasuredCorrosion

Rate (mils/yr)CPA SpikedMineral Oil 0.5 0 2.1CPA SpikedMineral Oil 1.0 0 3.5CPA SpikedMineral Oil 3.0 0 25.2

Whole Crude 0.06 3.2 18.8Whole Crude 4-5 0.1 11.8

650+ 1.2 .33 6.2VGO 5.9 0.96 48.4

Corrosivity vs. TimeCPA (TAN=3.0) Spiked Oil Test

0

500

1000

1500

2000

2500

3000

0 1 2 3 4 5 6

Time (hours)

Cum

ulat

ive

Cou

pon

Mas

s Lo

ss (µ

g)

0

100

200

300

400

500

600

700

Oil

Tem

pera

ture

(°F)

Data Points Fitted Data Oil Temperature

Corrosion Rate = 25.2 mils/year

Corrosivity vs. TimeVGO Test

-100.0

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Time (hours)

Cum

ulat

ive

Cor

rosi

on (µ

g/in

²) or

Tem

pera

ture

(°F)

Cumulative Corrosion Data (µg/in²) Oil Temperature (°F) Fitted Cumulative Corrosion (µg/in²)

Sampling of Crude Oil TestsRepresentative Data from Crude Oil Corrosivity Measurement Experiments

0

500

1000

1500

2000

2500

3000

3500

4000

0 1 2 3 4 5 6Time (hours)

Cum

ulat

ive

Cor

rosi

on (µ

g)

0

100

200

300

400

500

600

700

Oil

Tem

pera

ture

(°F)

CPA Spiked Mineral Oil, TAN=3.0 CPA Spiked Mineral Oil, TAN = 0.5Whole North Sea Crude A, TAN = 2.24 Whole North Sea Crude B, TAN = 2.24Composite AGO 660-952°F, TAN = 0.65 Angola VGO, TAN = 2.2Oil Temperature (Representative)

Applications

Versatile Oil Corrosivity MeasurementWhole Crudes, Fractions, AGO’s, VGO’s

Database DevelopmentModel Development

Time Resolved Corrosivity Data Can be Used as Input toProprietary Models

Crude Oil Blend OptimizationMeasure Corrosivity as Function of Blend Ratio

Inhibitor ResearchDetermine Inhibitor EffectivenessDetermine Optimum Concentration

Applications(cont.)

In-Plant On-line Corrosion MonitoringMaterials Selection

Can Measure Corrosion Resistance of Various Materials

Operating Conditions ResearchTemperature, Shear Stress, Pressure

Research and DevelopmentCorrosivity ModelsCorrosion Inhibitor Optimization

Specifications

Sample Volume 1500 mlCurrent Stand Limitations

Maximum Oil Temperature 650°FMaximum Shear Stress 500 PaMaximum Oil Pressure 100 psi

Possibility of Upgrading to HigherOperating Conditions If Needed

ConclusionsSwRI has developed a unique, versatileand highly sensitive method toaccurately determine the corrosion rateof oils.This method is designed as a tool toallow the buyer or seller of opportunitycrudes to make informed decisions oncrude values and for the refiner toassess crude corrosivity before it isrefined.

Conclusion (cont.)

Interested in forming a Joint IndustryProject (JIP) to further develop thistechnology.

Investigation of– Shear Stress Effects– Temperature Effects– Other Refinery Conditions

Standardization of Corrosivity MeasurementProcedureDevelopment of an Oil Corrosivity Index