biodiesel fuel quality
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Biodiesel Specifications, Fuel Quality and Technical
Overview
National Biodiesel Board Diesel Technician Outreach Program 2010
Quality, Quality, Quality B100 must meet D 6751 prior to blending to insure trouble-
free use of B20 and lower blends
BQ-9000 fuel quality program helps to promote high quality fuel from producers and marketers
B20 and lower blends are recommended since most of the research and successful use of the fuel has been with these blends See NBB Toolkit document “Use of Biodiesel Blends Up to B20” for
more information
Blends over B20 require special precautions and should only be used by knowledgeable and experienced users See NBB document “Guidance on Biodiesel Blends Above B20” for
more information: http://www.biodiesel.org/pdf_files/fuelfactsheets/Use_of_Biodiesel_Blends_above_%2020.pdf
Why care about biodiesel quality?
Off specification biodiesel can cause engine operability problems
Quality is critical to continue to grow the industry There is NO room for off-specification fuel Customers need to receive consistent
quality from lot to lot, batch to batch Must be on-spec for tax credit and to be
legal fuel
Summary Biodiesel production review Key elements in ASTM Specifications and Standard
Test Methods ASTM Specification D 6751 – 09, the specification
of B100 (biodiesel) fuel is described in detail. Key properties of B 100 are discussed in terms of
their tests and specifications. Alternative testing procedures Other issues affecting fuel quality
Review of the Production Process
Biodiesel is produced by a chemical reaction between methanol (or ethanol) and an oil or fat, in the presence of a catalyst.
Requires a strong basic catalyst (NaOH or KOH) The reaction is called “Transesterification”
Changing one ester (vegetable oil) into another ester (biodiesel)
Oil + Alcohol yields Biodiesel + Glycerol
Transesterification (the biodiesel reaction)
Fatty Acid Chain
Glycerol
Methanol (or Ethanol)
One triglyceride molecule is converted into three mono alkyl ester (biodiesel) molecules
Biodiesel
Triglyceride
Potential Impurities: in Biodiesel
Methanol – Degrades some plastics and elastomers, corrosive; Can lower flashpoint to unsafe levels (fire safety)
Unconverted/partly converted oils (bound glycerin) – Results in very poor cold flow properties, injector and in-cylinder deposits, potential engine failure
Free Glycerin – Results in injector deposits, clogged fuel filters, deposit at bottom of fuel storage tank
Catalyst (caustic, NaOH) – Excessive injector, fuel pump, piston, and ring wear, filter plugging, issues with lubricant
All are limited by ASTM D6751 specification
ASTM Standards for Biodiesel ASTM D6751 is the approved standard for B100 for
blending up to B20, since 2001 Performance-based standard: Feedstock and Process
Neutral D975 – Add up to 5% biodiesel in Petrodiesel D396 – Add up to 5% biodiesel in Heating Oil D7467 – New standard for on/off road blends of B6
to B20
B100 Blending Component Specification
Major steps forward for passage of biodiesel blend specifications
Critical for obtaining OEM approval
Critical for ensuring that biodiesel performs as advertised so market can grow
D6751-09 Requirements
McCormick, R.L, Westbrook, S.R. “Biodiesel and Biodiesel Blends” Standardization News, page 28, April 2007
Property Test Method Limits Units
Calcium & Magnesium EN 14538 5 max ppm(ug/g)Alcohol control
either Flash Point D 93 130 min. Degrees C or GC methanol EN 14110 0.2 % Volume
Flash Point D 93 93min. Degrees CKin. Viscosity, 40C D 445 1.9 - 6.0 mm?/sec.Sulfated Ash D 874 0.02 max. % massSulfur S500 D 5453 0.05 max (500) % mass (ppm)
S15 D 5453 0.0015 max (15) % mass (ppm)Copper Corrosion D 130 No. 3 max.Cetane number D 613 47 min.Cloud Point D 2500 Report degrees CCarbon Residue D 4530 0.05 max. % massAcid Number D 664 0.50 max. mg KOH/gFree Glycerin D 6854 0.020 % massTotal Glycerin D 6854 0.240 % massPhosphorous content D 4951 0.001 max % massDistillation, T90 AET D 1160 360 max degrees CNa/K, combined EN 14538 5 max ppm(ug/g)Oxidation Stability EN 14112 3 min hours
(Visual Appearance)D 4176 Free of un-dissolved water, sediment and suspended matter
BOLD = BQ-9000 Critical Specification TestingOnce Production Process Under Control
B6-B20 Blend Specification
Oxidation Stability is 6 hours
Cold Soak Filtration Test included
Acid Number Reduction
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Impact of Blended Specs More large fleets are using B20 Nearly 55% of OEMs in the U.S. now support B20
or higher blends in at least some of their equipment
Biodiesel blends are the only non-petroleum diesel substitute to have officially sanctioned ASTM specifications
Quality is further improved, fuel specs can be enforced by regulatory bodies (supported by NBB)
Biodiesel companies have made process changes in order to meet D6751
Biodiesel Pump LabelingNo Label Required: Fuel blends containing no more than five percent
biodiesel and no more than 5 percent biomass-based diesel and that meet ASTM D975.
Labels Required: Fuel blends containing more than five but no
more than 20 percent biodiesel or biomass-based diesel.
Fuel blends containing more than 20 percent biodiesel or biomass-based diesel.
Separate Labels for Biodiesel (Blue Labels) and Biomass-Based Diesel (Orange Labels)
BQ-9000 Fuel Quality Program
BQ-9000 ProgramBiodiesel Industry’s equivalent to an ISO 9000 program for biodiesel production & distribution companies as well as testing labs
BQ-9000 works hand-in-hand with the ASTM specifications for biodiesel
Quality Control System covers biodiesel manufacturing, sampling, testing, blending, storage, shipping, distribution
ASTM Grade Fuel, BQ-9000 Companies
BQ-9000 Status
Since 2005, there has been a substantial increase in interest in the NBB’s BQ-9000 Quality Program
There are now three BQ-9000 designations: Producer (make it to spec) Marketer (buy spec, keep it in spec, blend it right) Certified Laboratories (test it to ensure it is in spec)
We now have 60 total companies BQ-9000 certified (37 producers, 23 marketers)
75-80% of the biodiesel volume in the U.S. is now made by BQ-9000 producers, and more certifications are in process
Many OEMs are now either requiring or strongly encouraging BQ-9000
•Under guidance of B20 Fleet Evaluation Team (OEM’s, NREL, NBB)
•Samples obtained nationwide from biodiesel blenders (27 samples)
•85% of samples tested met the ASTM D6751 specification
2004 B100 Quality Survey
Four samples failed with high levels of:
•phosphorus (lube oil contamination?)
•total glycerin•acid number•acid number and total glycerin
2006 B100 Quality Survey
A subcontractor visited the site of a biodiesel blender, usually a terminal operator or jobber, to collect the B100 sample
32 B100s, 6 B99s, and 1 B50
59% of B100 samples tested fail the D6751 specification Importantly, 30% fail total glycerin – immediate operational
problems in cold weather Other issue of concern is 20% failure rate for Na+K Compares to 15% failure rate in 2004 survey Samples were collected randomly, not on production volume basis
• Biodiesel, based on production volume, may have different failure rate
• Poor quality batch may have contaminated larger fuel lot
2007 B100 Quality Survey
Collect B100 samples directly from producers and analyze for properties most likely to impact engine performance and emission control systems Flash point, oxidation stability, acid value,
free and total glycerin, cloud point, Na+K, Ca+Mg, P, water & sediment
First survey that will link test results to production volume
Results presented at recent NBB meeting
Survey results 56 out of 107 producers participated in 2007
survey or 70% of the 2007 US market –Reasons for not participating are likely due to lack of feedstock availability
Wide variety of feedstocks represented Meeting the specification is independent of
producer size or feedstock Small producers failed specifications more
often than medium or large producers –Small producers: 28% of samples passed –
Medium producers: 68% of samples passed –Large producers: 94% of samples passed
How do you ensure quality?
Biodiesel Fuel Quality is determined by: 1. Feedstock quality 2. Production process 3. Post-Reaction monitoring 4. Analytical Capability5. Handling and Storage **CRITICAL
Critical Parameters
Flashpoint, °CAcid Number, mg KOH/gTotal and Free Glycerin, % massWater and Sediment, volume %Cloud point, °COxidative Stability, hr Sulfur, ppmVisual appearance
Flash PointMethod ASTM D 93 Changed 2007- Limit: 93ºC minimum Temperature A sample is heated in a close vessel and
ignited. When the sample burns, the temperature is recorded.
Alcohol Control One of the following must be met:
1. Methanol content EN 14110:
0.2 max % volume
2. Flash point D 93 : 130 min °C
Flash Point Testing
Water and Sediment Method D 2709 Limit of 500ppm,
examining the free water content
100 mL of sample are centrifuged at 800 rcf for 10 min at 21° to 32°C in calibrated tube.
Water and Sediment
Biodiesel can absorb 1500 ppm of water while diesel only 50 ppm.
Free water can cause corrosion of fuel injection parts.
Housekeeping issue Precipitates above
cloud point
Karl Fischer : Moisture Determination
Acid Number Test Method ASTM D
664 Limits: 0.5 mg KOH/g
maximum pH sensitive electrode May also be
determined using indicators
Sulfated Ash Test Method ASTM D 874 Limits: 0.020 % mass maximum Sample ignited and burned Ash + carbon (C removed by
H2SO4) Indication of concentration of
metal additives (Ba, Ca, Mg, Na, K, Sn, Zn)
More than 0.020 % indicates residual soap & catalyst
Free and Total Glycerin Test Method ASTM D 6584 Limits: 0.020 % mass free glycerin 0.240 % mass total glycerin Gas Chromatography with FID detection Quantifies glycerol, mono-, di- and
triglycerides
Production Factors: Total Glycerol
Measured with gas chromatograph (ASTM D6584) and requires a skilled operator.
Saturated monoglycerides have very low solubility in biodiesel.
If too high, there may be problems with fuel filter plugging and fuel stability.
Good conversion
Sulfur
Test Method ASTM D 5453 Limits: 0.05 % mass maximum S oxidized to SO2 at high
temperatures UV fluorescence of emitted gases SO2
SO2* SO2
S limits dictated by environmental considerations (S15 or S500)
EPA regulations Feedstock variation
Cloud point Test Method ASTM D 2500 Limits: No established limits Reported in ºC Sample cooled and examined visually until first
cloud appears. Indicates the lowest temperature at which fuel is
usable. Generally higher than diesel.
Cold Flow Wax molecules in diesel fuel and biodiesel tend to
crystallize at low temperatures. Crystals agglomerate to form large masses. This can cause filter plugging and eventually the fuel
will become a solid mass. Soy biodiesel gels at approximately 32°F #2 petroleum diesel fuel gels at 10 to 14 °F. Biodiesel from saturated/tallow feedstocks can gel as
high as 50-55°F. In contrast, petroleum diesel fuel is a mixture of
hundreds of different compounds that solidify at very different temperatures. So, even if some compounds crystallize at a relatively high temperature, many other compounds will stay liquid to a much lower temperature.
Watch your soap & water content!
Cloud Point & CFPP
Cold Soak Filtration Test
Developed in response to questions about precipitates above the cloud point
Character of precipitates may vary with feedstock
Method is now incorporated in the D6751
Method will be mandatory annex in D6751 until test method is balloted and written
ASTM Subcommittee 14 is working to further develop test method
-6°C
-10°C -12°C
-8°C
Cold Soak Filtration Test Method
Preheat fuel at 40°C for 3 hours to remove thermal memory then hold at room temp for 24 hours
Soak 300 mL sample at 4°C for 16 hours and let return to room temperature Time will vary with degree of
saturation of feedstock Filter fuel using 0.7m filter
and constant vacuum Record time to filter fuel
If fuel does not filter, record time stopped and volume filtered
Oxidative Stability Equipment: Rancimat or OSI Method: EN 14112; 3 minimum hours Equipment cost: approximately 17- 20k Recent addition to ASTM 6751 Products of oxidation in biodiesel are various acids or
polymers, can cause fuel system deposits and lead to filter plugging & fuel system malfunctions.
Additives can improve the oxidation stability performance of biodiesel.
Fuel oxidation Biodiesel will react with oxygen from the air
to form polymers, acids, etc. Acids:
Presence indicated by increasing Acid Value Cause corrosion of metal components Corrosion can be aggravated by water
Polymers: Sediments that can plug fuel filters and coat
metal surfaces
Class I & II metals: Ca/Mg/Na/K
Calcium & Magnesium & Sodium & Potassium can be in biodiesel as abrasive solids or soluble metallic soaps.
Solids contribute to injector, fuel pump, piston, and ring wear, & engine deposits.
Soluble metallic soaps have little effect on wear, but filter clogging & engine deposits
These compounds may also be collected in exhaust particulate removal devices
Less Critical Parameters Cetane Distillation Temperature Viscosity Carbon Residue Phosphorus Copper Strip Corrosion
Fleet and Distributor Biodiesel Testing
Saftest Completeness of Reaction (3/27 Methanol Test) Soap test: AOCS method Wilkes Infraspec Paradigm Sensors Fleet Biodiesel pHLip Test Wika Water test Microbial growth, algae-x
MP Biomedicals
Completion of Reaction Dissolve 3 ml of biodiesel in 27 ml of
methanol. The biodiesel should be fully soluble in
the methanol forming a clear bright phase.
If you observe un-dissolved material at the bottom of the sample the reaction did not proceed to completion
Each ml of undissolved material corresponds to 4% by volume.
0.2139 Bound Glycerin
Although cloudy, there were no droplets of precipitate.
0.0900 Bound Glycerin
Crystal clear, no cloudiness or precipitate.
Samples Passing 3/27
0.9256 Bound GlycerinNote the falling droplets of unreacted oil.
Samples Failing 3/27
1.8260 Bound Glycerin
Biodiesel Conversion Test
Acid Number Qualitative Tests
Soap- AOCS test method Gels at ambient temperature as little as 5% Cause problems with glycerol separation and
washing Soap can be split by acidulating Soap is usually clear and very viscous Methanol will act as a cosolvent and keep soap in
solution with the biodiesel High soap levels = high sulfated ash number High FFA and water content lead to soap formation
in process
Soap TestTitrating from blue/green to straw yellow….
Wilkes InfraSpec
measures percent biodiesel in diesel fuel, ethanol in gasoline, water in ethanol as well as total glycerides during the biodiesel
pass/fail determination in less than 5 minutes.
Paradigm Sensors
* Paradigm Sensors’i-SPEC™ tests TOTAL GLYCERIN in blended fuels (B6-B20), which is in accordance with ASTM proposal that the biodiesel portion of the fuel must meet ASTM 6751 prior to blending.
Fleet Biodiesel
pHLip Test
Wika Water Test
Microbial growth Certain varieties of bacteria and fungi can grow in diesel fuel
tanks. Growth occurs at the interface of the fuel and water at the
bottom of the fuel tank. Water must be drained from tank bottoms on a regular basis. ULSD Biocides are available to control microbial growth.
Dead microbes can still plug filters. Water elimination and prevention is preferred over treatment.
Bacteria Growth
Fungal Growth
Operational issues Microbial growth – ULSD & moisture
Treat your storage tanks for moisture/biocide Incomplete reaction Aged fuel Cold Flow Low energy content (not harmful)
Fuel filter plugging is the most common
operational issue
Certificate of Analysis
Biodiesel Quality Standard
ASTM D 6751 Standards Fuel quality is critical
for proper functioning Standards ensure
satisfactory operation in diesel engines
BQ 9000 Certification Certifies biodiesel
producers and markers Feeling of confidence for:
Biodiesel Producers Engine and Vehicle
Manufacturers Distributors Consumers
In Summary
Purchase fuel from known quality producer
On-site and in-process analysis is essential
Watch for residual contamination Correct product handling and storage
procedures is essential Final product must meet the current
revision of ASTM D 6751
Biodiesel Fuel Quality Resources www.biodiesel.org http://www.bq-9000.org/ www.me.iastate.edu/biodiesel http://www.uidaho.edu/bioenergy/index.html http://www.cytoculture.com/ http://www.biodieselmagazine.com
NBB Resourceswww.biodiesel.org
Biodiesel Training Toolkit
News Releases & Information Resources
Technical Library, Spec Sheets & Videos
OEM Warranty Positions on Biodiesel
U.S. Diesel Vehicle List
www.BQ-9000.org Listing of BQ-9000 Certified Companies
www.biotrucker.comListing of BioTrucker retail sites
www.allthingsbiodiesel.comBiodiesel merchandise, literature, pump labels and more!