Storing & Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses - - PowerPoint PPT Presentation

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Corrosion in Systems Storing & Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation

Anne Marie Gregg Seth Faith, Barry Hindin, Michael Murphy, Kevin Ralston, Steve Risser, and Doug Turner Battelle Memorial Institute Brad Hoffman, Tanknology October 8, 2012

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Does this look familiar?

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From as early as 2007, PEI started receiving reports

• f unusually severe and accelerated corrosion in

ULSD USTs

Occurring in as little as 6 months

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Initial observations

• Corrosion appears in both liquid and vapor areas
• Metallic wetted and unwetted areas are

susceptible

• No reported evidence of corrosion

– at refineries – within pipelines

• No apparent connection between

– geographical region – supplier – age of equipment

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Equipment Issues Reported

• Filters clogging/requiring

more frequent replacement

• Seal/gasket/o-ring

deterioration

• STP replacement/column

pipe wear/motor problems

• Tanks rusting/leaking
• Meter failure
• Line leak detectors damaged
• r broken
• Automatic nozzle shutoff

failure/shorter lifespan

• Tank probes malfunctioning
• Check valves not seating
• Shear valves not

sealing/failing tests

• Swivels failing/shorter

lifespan

• Dispenser leaks/failures/

premature replacement

• Solenoid valves

clogged/failing

• Corrosion on the riser pipe
• Pipe failure

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Regulatory Regulatory D Drivers rivers

• 2005: Energy Policy Act of 2005:

– Established Renewable Fuel Standard

• 2006: US EPA Clean Air Highway Diesel final rule

– Required 97% reduction in sulfur content of highway diesel fuel – Low Sulfur Diesel Fuel (LSD) : 500 parts-per-million (ppm)  15 ppm in ULSD

• 2007: Energy Independence and Security Act of 2007

– Set goals for biofuels production

• Current status

– ULSD: 80% of the change over occurred in 2006 and the remaining 20% occurred by 2010 – Ethanol: Over 90% of all gasoline is being sold with 10% ethanol content

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Who’s Who Clean Diesel Fuel Alliance (CDFA) Taskforce

• www.clean-diesel.org

Contracted with Battelle teaming with Tanknology through competitive RFP to provide objective evaluation

• Association of American

Railroads

• American Petroleum Institute
• Ford Motor Company
• National Association of

Convenience Stores

• National Association of Truck

Stop Operators

• Petroleum Equipment Institute
• Petroleum Marketers

Association of America

• Steel Tank Institute

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Project Design

Hypotheses Investigation

• Phase 1

– Industry observations, anecdotal information, and Tanknology inspection database

• ~12 potential hypotheses
• Concluded 3 working hypotheses
• Phase 2

– Detailed investigation of 6 sites

• Field sampling
• Chemical and microbiological components

– Interpretation of results – Concluded final hypothesis

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Project Design Phase 2: Working Hypotheses

• 1. Aerobic and anaerobic microbes

produce byproducts that establish a corrosive environment in ULSD systems

• 2. Aggressive chemical specie(s)

(e.g., acetic acid) present in ULSD systems promote aggressive corrosion

• 3. Additives in the fuel contribute to

the corrosive environment in ULSD systems

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Selecting the Inspection Sites

Minimize Variety in:

• Tank Material
• Fuel Throughput
• Tank Size

Maximize Variety in:

• Installation Year
• Prior Fuel Service History
• Geographic Location

thereby adding variety in:

– Climate – Fuel Supplies (refinery) – Fuel Routes (pipelines, barge) – Carriers (company owned, third party)

12 sites were considered, 2 did not have symptoms

6 Sites Selected

• 1 site that was believed to not

have symptoms of corrosion

• 5 sites with a history of severe,

rapidly induced corrosion

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Data Summary Site Characteristics

Site ID NC-1 NY-1 "Clean Site" NY-2 CA-1 CA-2 CA-3 Inspection Date 8-Feb-12 15-Feb-12 16-Feb-12 21-Feb-12 22-Feb-12 23-Feb-12 Year of Tank Installation 1998 2008 1988 1990 1991 1991 Tank Capacity (gallons) 17,265 12,000 6,000 10,000 12,000 6,000 Tank Material FRP- double FRP-double FRP-single FRP- double FRP- double FRP- double Tank Diameter (inches) 120 120 92 92 120 92 Monthly Throughput (gallons/month) 29,000 18,000 6,500 26,000 20,000 25,000 Product Level (inches) 27.5 48 35 15 49 28 Filter Replaced Date 24-Jan-12 unknown filter not identified 2-Feb-12 13-Jan-12 9-Jan-12 Biocide Treatment History December 2011 unknown 2 times in past year unknown none unknown

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Inspection and Sampling Plan

• Data collected on inspection checklist,

in laboratory record book, with photos and video

• Each site inspected in February 2012
• Samples collected

– Fuel – Water bottom – Vapor – Bottom sediment – Scrape samples

• Analyses conducted by 5

independent laboratories

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Genomics Biological Analysis

• Extracted DNA from 16

samples

• Analyzed 4 samples from 3

sites using genomics techniques

– Compared data to library of DNA to identify organisms – Bacteria, fungi, viruses, and metabolic pathways

• Confirmatory test for the presence of bacteria on

samples with DNA yield too low for genomics analysis

– PCR amplification of 16s rRNA gene

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Dominant Organisms by Site

Genera NY-1 NY-2 CA-2 CA-2 Gluconacetobacter sp. 35% 44% 53% 55% Acetobacter pastuerianus 33% 23% 24% 19% Gluconobacter oxydans 4.0% 3.0% 20% 19% Lactobacillus sp. 1.0% 34% 0.1% 4.0% Fungi (e.g. Zygosaccharomyces sp) 9.0% 0.3% 0.1% 0.2% Bacteriophage (virus) 7.0% 2.0% 0.8% 0.7% Gammaproteobacteria (hydrocarbon-degrading) 4% 5% 0.3% 0.3%

Bacteria of the acetic acid producing family (Acetobacteraceae) were prevalent at three inspection sites. The hydrocarbons contained within the diesel fuel may not be the primary carbon source for the consortium of bacteria present.

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Diversity Assessment

NY-1 NY-2 CA-2 CA-2 Historical sediment samplesc

Shannon’s diversity (H) 2.6 2.7 1.5 1.7 4.8 - 5.3 Shannon’s equitability (EH) 0.23 0.22 0.13 0.14 0.74 - 0.80

As H approaches zero, an ecosystem (microbial) is dominated by very few species. EH assumes a value between 0 and 1, with 1 being complete evenness/diversity.

c Previous data from marine sediments (natural environmental samples) from research studies at Battelle

using the same genomics methods.

• All sites inspected displayed presence of bacterial DNA, although in

different abundances.

• The conditions of the ULSD tanks are conducive to growth of

limited, specialized organisms.

• Less unique organisms present in the community (H)
• Limited species that dominate the community (E)

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Chemical Analyses Summary

• Fuel

– Acetate and trace amounts of ethanol – 3 failing NACE ratings – Sulfur 5.9 - 7.7 ppmv

• Water

– Acetate, ethanol and glycolate – High conductivity, chlorides, and low pH at all sites

• Vapor

– High humidity, acetic acid, formic acid, and propionic acid at all sites

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Corrosion Inducing Factors

Conditions exist to lead to observed attack

• 1. Corrosion of metallic components– observed

during inspections

• 2. Ingredients for a corrosive aqueous electrolyte

exist

– Water, oxygen, acid content, aggressive species (Chlorides) at all 6 sites

• 3. Microbiological activity determined at all 6 sites
• 4. Mechanism for electrolyte and aggressive species

dispersion exists during fuel deliveries

– With higher vapor pressure than ULSD, acetic acid is dispersed into vapor space

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Corrosive Electrolyte Acetic Acid/Acetate Content

NC-1 NY-1 NY-2 CA-1 CA-2 CA-3 Vapor-Acetic Acid (ppmv) 0.57 1.8 3.6 7.8 9.5 16 Fuel-Acetate (ppm) ND 7.7 2.8 2.7 ND 5.9 Water-Average Acetate (ppm)a 16,500 9,000 21,000 22,500 17,500 20,000 Relative Humidity (%) a 90.9 83.3 95.5 73.7 71.8 95.2 In-tank Temp (°F)a 57.1 46.8 44.7 61.8 66.4 58.2

a average of two or more results

ND = Not detected

• Acetic acid was measured in all vapor samples.
• Acetate was measured in all water samples and 4 of 6 fuel samples.
• Acetic acid was identified in 75% of the scrape samples and from all sites.
• Other acids were determined and should be investigated (formic, glycolic, propionic)

Data indicate that acetic acid is the dominant acid species throughout the UST systems inspected.

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Estimated Ethanol Contamination from Unknown Source(s)

• If entering system with fuel, ethanol will separate into the

water bottom (fuel-ethanol < water-ethanol)

• Ethanol was used for decontamination of sampling

equipment – unlikely contamination source

– At all sites, fuel was sampled first, then the water bottom. Liquid sampling equipment was decontaminated once sampling was complete at each site.

NC-1 NY-1 NY-2 CA-1 CA-2 CA-3 Fuel-Ethanol (vol%) 0.04 0.01 0.17 0.06 ND ND Water-Ethanol (vol%) 3.17 0.66 0.45 0.40 ND 0.04

Ethanol was unexpectedly identified and measured in liquid samples, suggesting ethanol is contaminating or forming in the fuel.

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Possible Ethanol Sources

• Switch Loading

– Diesel fuel is often delivered in the same trucks as ethanol-blended gasoline.

• Ventilation Systems

– ULSD USTs that have been converted from a gasoline tank could have manifolded ventilation systems with gasoline tanks.

• Symbiotic Biological Activity

– Microbes or fungi using or producing ethanol

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Is it possible for Acetobacter to create enough acetic acid in the UST environment to cause the corrosion?

• Upper bound on the amount of acetic acid required

– Assume 1 kg, or 1.54 mol of corrosion product in the tank and that the corrosion is composed solely of iron(III) acetate, [Fe3O(OAc)6(H2O)3]+ OAc- – 10.8 mol or 650 g of acetic acid needed

• One of the most common reaction pathways for acetic acid

production = (1 mol of ethanol per 1 mol of acetic acid)

– 10.8 mol of ethanol = ~500 g = ~0.63 L of ethanol – Assuming a 5000 gallon tank (18,950 L), this is equivalent to an ethanol concentration of 0.0033% by volume or 33 ppmv

Yes

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Can this amount of acetic acid be created in a timeframe consistent with the observations?

– Acetic acid production has been reported steady at 4.55g/Lh for 27 g (dry weight) of Acetobacter in a 1-L reactor

• C2H5OH + O2 → CH3COOH + H2O

– If there is sufficient O2 and ethanol, ~650 g of acetic acid can be produced in the course of 1 week (144 hours)

Yes

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Final Hypothesis and Study Conclusions

• Acetic acid was determined to be a likely cause of the

corrosion

– Ubiquitous in the USTs inspected and was not intentionally introduced

• A plausible source of the acetic acid is from Acetobacter

producing it as a metabolic by-product

• The components for identified Acetobacter to thrive were

present in the tested USTs (oxygen, water, low pH, ethanol)

• Acetic acid repeatedly “doses” the equipment when the UST

contents are disturbed

• It is feasible for enough acetic acid to be produced in the

timeframe being reported

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Continued Research…

• Larger and more diverse sample set

– Different tank material, size, throughput – Comparison of sites with and without the issue

• Longitudinal design

– Multiple samplings over time at same sites

• Investigate sources of ethanol contamination

– Switch loading practices – Symbiotic biological activity (metagenomics)

• What other factors are involved and how much

influence do they have?

– Role of formic and glycolic acids, other unknown factors

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The report is posted at: http://www.clean-diesel.org/pdf/ULSDStoringSystemCorrosion.pdf Anne Marie Gregg gregga@battelle.org 614-424-7419

Thank You to the CDFA, Marathon, Chevron, Ford, Inspection Site Owners/Operators, and Tanknology