Fuel Quality and Principles of Particle Counting

Gary Bessee, DirectorSteve Westbrook, Institute Scientist

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Outline

� Introduction the Southwest Research Institute (SwRI)� Resumes for Gary Bessee and Steve Westbrook� Fuel Quality

– Storage Stability– Thermal Stability– Typical contaminants– Possible remediation for contaminants

� Particle Counting– Principles of Light Blockage– ISO 4406 Cleanliness code

� Questions

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Southwest Research Institute (SwRI)

� Founded in 1947�Non-profit�Revenue from contracts�Applied RDT&E services� Physical sciences & engineering� Broad technological base�Capital intensive operation

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SwRI – www.swri.org

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Bridging the Gap

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Fundamental Science

Universities, National Labs

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Å B r i d g i n g t h e “ V a l l e y o f D e a t h ” Æ

Industry

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Divisions at SwRI

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• Applied Physics

• Applied Power

• Chemistry and Chemical Engineering

• Defense and Intelligence Solutions

• Powertrain Engineering

• Fuels and Lubricants Research• Intelligent Systems

• Mechanical Engineering

• Space Science and Engineering

Gary’s Resume

� 35+ years at SwRI working in filtration, fuel cleanliness, and wear studies� Most work involves cleanliness of hydraulic fluid, lubricant oils,

and diesel and aviation fuels.� Member of SAE Filter Test Methods Committee for 26 years� US delegate for 20 years for fuel water separation and multi-

pass filtration testing� Member of ASTM and attend other various technical societies

– CRC, AFC, IASH, etc.

� Co-author of filtration chapter in ASTM Automotive Lubricants and Testing and multi SAE and other technical papers� Hosted 10 International Filtration conferences

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Steve’s Resume

� Mr. Westbrook has 38+ years experience in standardized and non-standardized testing of petroleum fuels and lubricants. He has extensive experience in distillate fuel quality, fuel stability testing, laboratory test development, technical liaison in fuel-related field problems, and development of field-tests for diesel fuel stability and cleanliness. He has conducted research on fuel stability additives, diesel fuel-degradation reaction mechanisms, and the effects of fuel container surfaces on fuel quality. He also has extensive experience with fuels from alternative sources, especially fuels for diesel engine applications.

� Mr. Westbrook has authored numerous publications on fuel cleanliness, fuel stability and the long-term storage of fuel. He conducted studies of the application of advanced analytical methodologies for in-the-field analysis of fuels; specifically, on the use of near-infrared spectroscopy for estimation of fuel properties and the use of portable test devices for fuels analysis. He has extensive experience in the study of biodiesel, biodiesel oxidation, and oxidation test methods. Recent work has involved characterization of liquid fuels as it pertains to fuel properties.

� PROFESSIONAL CHRONOLOGY: Guadalupe-Blanco River Authority: laboratory analyst, 1978; Southwest Research Institute: 1979-[research scientist, 1979-83; senior research scientist, 1983-90; group leader, 1990-4; principal scientist, 1994-9; manager, 1999-2005; principal scientist, 2005-7; staff scientist, 2007-15; institute scientist, 2015-present].

� MEMBERSHIPS: ASTM International; International Association for Stability, Handling, and Use of Liquid Fuels. A Fellow of ASTM International. Current chairman of ASTM Subcommittee D02.E on Burner, Diesel, Marine and Non-Aviation Gas Turbine Fuels. Member of the ASTM Committee on Technical Committee Operations. Past chairman of the International Association for Stability, Handling, and Use of Liquid Fuels; and, currently on the Board of Directors. Past chairman of ASTM Section D02.E.05 on Fuel Stability and Cleanliness, Section D02.09.A on Oxidation of Motor and Aviation Gasolines, and Section D02.09.B on Oxidation of Middle Distillate Fuels.

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Fuel Quality and Contaminants

Fuel Quality and Contaminants

Topics for Discussion

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� Possible issues with stored diesel fuel� Impact of biodiesel in stored fuel�What leads to contaminated fuel in storage� Summer fuel vs. winter fuel� Corrosion�Ways to minimize the risk of contamination

The “Fuel System”

Each Segment is Another Possible Point of

Contamination

� End User’s Storage Tanks� Vehicle Fuel Tank and Engine� The Fuel System Also Includes:

– Crude Source– Refinery and Refining Processes– Pipeline– Terminal– Delivery Trucks

Diesel Fuel in Storage

� ASTM D975, Table 1, is the specification most commonly used for diesel fuel in the U.S.� The specification includes requirements for fuel that is typically

expected to be used within about 6 months.� Most diesel fuel is not manufactured with the expectation that

it will be put in long-term storage and be ready to provide trouble-free use under emergency generator situations.� As a general rule, the properties included in D975 will not

significantly change during long-term storage of the fuel.� Properties not included in D975, Table 1, are more often than

not, the most potentially problematic when it comes to trouble-free use of the fuel

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Factors Affecting Fuel Cleanliness And Product Stability� Composition And Refinement� Product Contamination

(Blending Of Pipeline Interfaces)� Use Of Non-dedicated

Transportation/distribution Systems� Inadequate Housekeeping

Procedures� Ground Water Leakage

� Storage Environment

� Equipment Design (Fuel Recirculation Rate, Fuel Tank Construction)

� Consumption/turn-over Rate

� Absence Of F/S Equipment

� Use Of Proprietary Additives

� Microbiological Growth

� Ambient Temperature

Possible Issues with Stored Diesel Fuel

� Accumulation of water and particulates during storage� Growth of microbial contaminants� Oxidation of fuel to form particulates and acidic species� Corrosion� Precipitation of wax during cold weather� Plugged fuel filters/screens/lines are the most common cause

of fuel-related problems; and, the above issues can all contribute to plugging

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Water

� The Most Common Fuel System Contaminant is Water� It Can Come From:

– Transportation, Delivery And Intermediate Storage– Tank Breathing– Dissolution Of Dissolved Water– Rain: Through Fill Pipes And Other Openings– Ground Water: Through Leaks In Underground Tanks

Water

� Increases Corrosion And Wear� Freezes During Low Temperature Operation� Carries Dissolved Acids�Water Is Necessary For Microbiological Growth

Biodiesel

3.1.1 biodiesel, n—a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100.

ASTM D 6751, Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels:

Experiences in Use

� In General, When There Have Been Biodiesel-Related Problems in the Field, They Have Been the Result of:

– Off Specification / Poor Quality Control– Low Temperature Operation

� Look for the BQ-9000 Label in Order to Reduce the Chance of Off-Spec Fuel

Biodiesel Is Not:

� Coal Slurries� Raw Vegetable Oils and Fats� Non-Esterified Oils� Hydro-treated Oils and Fats� Blends With Diesel

The Influence of the Biodiesel Feedstock

�Different Feedstocks Result in Different Biodiesel Chemical Compositions and Properties� The User Should Be Concerned with the Properties

of the Finished Biodiesel Blend Rather Than the Specific Feedstock� Example: Tallow Has Better Thermal/Oxidative

Stability Than Soy But Poorer Low-Temperature Operability

Most Important Properties of B100(The Properties Most Subject to Change Because of Feedstock and Processing)

Oxidation Stability Controlled by RancimatUS: > 3hr ; EU > 6 hr

Free & Total Glycerine These are contaminants from the production process.

Flash Point Most importantly controls the amount of methanol left from production process

Cloud Point and Soon the Cold Soak Filtration

Control Low Temperature Characteristics

Acid Number Indicator of Production Quality and Oxidation

Ca, Mg, Na, & K Contaminants from the Production Process

In general, the remaining properties in D6751 are consistent regardless of feedstock.

Biodiesel Production

� The most important aspects of biodiesel production to ensure trouble free operation in diesel engines are:

– Complete Reaction– Removal of Glycerin– Removal of Catalyst– Removal of Alcohol– Absence of Free Fatty Acids

B5 Specification

� Up To B5 Is Allowed in D975 Diesel Fuel and D396 Heating Oil� No Changes to Properties in Table 1 of D975 and D396� B100 Must Meet D6751 Prior to Blending

B100 With 32°F Cloud Point After Several Days at 40°F

The precipitate is a combination of monoglycerides, soaps, and sterol-glucosides.

B100 was on-spec.

Plugged Filters(B5 to B10)

Monoglycerides recovered from a plugged fuel filter. Vehicle operated in the upper Midwest.

The B100 was on-spec.

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Fuel Stability Testing Variables

� Temperature� Oxygen� Contaminants

– H2O– Catalysts

� Container– Type– Configuration

Low Temperature Operability

Summer Fuel vs. Winter Fuel

� Throughout the U.S. fuel suppliers work to deliver fuel for use in winter months that will provide trouble-free use� But fuel purchased in the summer is not necessarily expected

to provide trouble-free use if used during cold weather months� As such, emergency generator owners/operators must be

cognizant of the low-temperature properties of the fuel in their system and must assume that the fuel will be needed during the coldest time of the year� Testing and monitoring the low-temperature properties is the

best method to reduce the potential for low-temperature operability problems

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Low Temperature Operability Nomenclature

These are some of the more commonly used terms

� MDFI – Middle Distillate Flow Improvers (Additives)– CFI – Cold Flow Improvers– WCM – Wax Crystal Modifiers– WASA – Wax Anti-Settling Additives– WAFI – Wax Anti-Settling Flow Improvers– DFFI – Diesel Fuel Flow Improvers– CPD – Cloud Point Depressants– PPD – Pour Point Depressants– EVA – Ethylene-co-Vinyl Acetate Polymers

� CFPP – Cold Filter Plugging Point (ASTM D6371)� LTFT – Low Temperature Flow Test (ASTM D4539)� PP – Pour Point (ASTM D97)� CP – Cloud Point (ASTM D2500)

Additives to Improve Low Temperature Operability

This figure used with permission of Infineum

Without additives, the wax crystals are large and can easily plug filters

Additives to Improve Low Temperature Operability

This figure used with permission of Infineum

With additives, the crystals remain smaller in size and often pass through the filter.

Fuel With and Without Low Temperature

Additives

� Low-Temperature flow improver additives can provide some protection against filters plugged by wax crystals� However, the wax crystals still precipitate at the cloud point

temperature, they just remain a smaller size� These smaller crystals can still precipitate and form a layer of

the fuel that is rich in wax� That wax-rich layer can still cause plugged filters and lines� This is especially true for fuel in storage

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Fuel Degradation Products Can Plug Filters

Notice that the particles, formed by the oxidation of fuel, are generally about 1 micron in diameter. The 1-micron particles are usually

agglomerated into larger clusters.

Microbial Contamination

� Sulfate Reducers Produce Toxic Hydrogen Sulfide And Elemental Sulfur; And Promote Pitting Corrosion Of Metal Tanks�Contribute To Sludge Buildup� Plug Filters And Screens� Increase Particulates And Fuel Turbidity�Metabolites Can Promote Corrosion And

Fuel Emulsification (Local pH Can Reach 3 With Fungus).

Fungus Contaminated Fuel

Fungal Colonies

Plugged Fuel Tank Screen

Microbial Growth

� Scanning Electron Micrograph of Fungus�Growth Is at Fuel /

Water Interface� Interwoven Mat

Structure Makes This an Effective Filter Plugging Contaminant

Corrosion

� The presence of water, microbial growth, alcohols, and acidic contaminants can all lead to corrosion of metals in the fuel tank

36Sep 28, 2010SwRI Workshop

How to Minimize the Risks

�Work with your fuel supplier to obtain fuel that is appropriate to your application� Monitor the fuel during storage to detect contaminants before

they become a problem� Judicious use of additives – many additives provide inadequate

or even no protection� Provide means to remove contaminants from stored fuel if

they are detected

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Principles of Particle Counters

Light Blockage

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Laser

Flow

Detector

Particles

Light Blockage

� Particle casts a shadow� Detector determines the

area of the particle� Calculates an equivalent

spherical particle

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Principles of Particle Counting

� Measurement is in 2-D� Orientation� Statistics

– More counts the better– To a limit

� Coincidence error– More particles than the sensor can

measure

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What Is Coincidence Error?

� ALL particle counters have a coincidence error level� Older counters were in the

25,000 particle range� Newer counters claim

125,000 particles� Two or more particles are

counted as one particle

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What A Particle Counter Can and Cannot

Measure?

� The particle counter will detect any contaminant that casts a shadow

– Dirt– Free Water– Air– Fuel degradation products

� Cannot identify what they are!!!� Cannot detect dissolved materials

– Fuel additives– Dissolved water

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ISO 4406 – Cleanliness Code

� ISO 4406 is an industry standard for

measuring the cleanliness of a fluid

� Provides a code for a range

� Typically reported for 4-, 6-, and 14

micron particles

� Parker unit adds the 30-micron size– Most likely free water

contamination

� Each ISO is a doubling of the

number of particles– ISO code 10 is 5 to 10 particles– ISO code 11 is 10 to 20 particles

� Example– ISO 18/15/13/10

� ISO 18 – 1300 to 2500, 4-micron

particles

� ISO 15 – 160 to 320, 6-micron

particles

� ISO 13 – 40 to 80, 14-micron

particles

� ISO 10 – 5 to 10, 30-micron

particles

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ISO 4406

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Calibration and reporting

� Particle counters are calibrated using NIST calibration fluid� Best to have Parker of the manufacturer calibrate the sensors

annually� Currently, most results are report in µm (c).� (c) currently is the default calibration� µm (b) calibration fluid is currently being used

– Results converted to match µm (c).

� For the users in the field, this has NO importance.� For someone trying to interpret the results, make sure all

results are reported as µm (c).

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Trend Analysis Using Particle Counters

� Obtaining data over a period of time can provide trends in the cleanliness of the stored fuel� As fuel breathes, dirt and moisture will enter the fuel storage

facility� If a filtration system is incorporated into the flow loop. The

operator can determine when the fuel is getting outside the desired cleanliness level and filter the fuel until it is below the desired level.� Slide 19 illustrates a sample data set illustrating the fuel starting

our clean, getting contaminated, and cleaning up several times over the recorded period of time

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Trend Analysis Using Particle Counters

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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71

ISO

440

6 Co

de

Time

Trend Analysis

4 6 14 30

Contaminated Fuel

Parker Data

� Parker system that was evaluated at SwRI is show to the right� Able to turn on and off when needed to

determine the cleanliness of the fuel� Output is ISO 4406 Cleanliness Code� Parker data (Slide 21) illustrates similar

trends as shown in Slide 19� Parker Specs

– http://www.parker.com/portal/site/PARKER/menuitem.de7b26ee6a659c147cf26710237ad1ca/?vgnextoid=fcc9b5bbec622110VgnVCM10000032a71dacRCRD&vgnextfmt=EN&vgnextdiv=687502&vgnextcatid=3042910&vgnextcat=ICOUNT%20PARTICLE%20DETECTOR

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Parker Data

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Contaminated Fuel

Marginal Fuel

Parker Particle Counter Installation

� The Parker unit is already enclosed in a sealed compartment.� Connect inlet preferably on the

pressure (downstream) of the system pump per Parker Operating Manual� The return sample from the

particle counter can go to slop for disposal or easier to have it return to the storage tank to reduce waste� Minimize the sampling lines to as

short as possible� Communication to IoT and

Watson to be performed by IBM

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Maintenance and Daily Operations

� Keep fluid in the particle counter at all times� If the lenses in the counter get dried, it will leave spots that will

show up as particles� Although the counter is enclosed, if it is best to locate under a

cover or protected from the elements� When in operation, verify fuel is flowing through the sensor� If no flow, check FAQ in Parker Operating manual� Heavy contamination may plug the small orifice in the counter� Discount the counter and back flush with and solvent, fuel or air

to remove blockage.� DO NOT use wire as it was scratch the lens� Annual calibration or verification can be performed by Parker

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