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The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
The importance of biodiesel stability
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The importance of biodiesel stability

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This paper was presented at the Biodiesel Exposicion Technica in Rosario Argentina in July 2007. It covers the basics of biodiesel stability issues and mechanical, operational and chemical solutions …

This paper was presented at the Biodiesel Exposicion Technica in Rosario Argentina in July 2007. It covers the basics of biodiesel stability issues and mechanical, operational and chemical solutions to protect biodiesel stability.

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  • 1. The Importance of Biodiesel Oxidation Stability by Phil Bureman Senior Regional Account Manager Nalco Company Olathe, Kansas USA [email_address]
  • 2. Where Is Olathe, Kansas, USA? The Cowboy Boot was invented in Olathe!
  • 3. Agenda <ul><li>Why is biodiesel oxidatively unstable? </li></ul><ul><li>Why is oxidation stability important in biodiesel? </li></ul><ul><li>What can be done mechanically, operationally and chemically to improve oxidation stability? </li></ul>
  • 4. Instability Is Also A Good Thing! Why is biodiesel unstable? Why is stability important? Managing biodiesel stability Malbec Grapes <ul><li>Biodiesel is derived from natural vegetable or animal feedstocks </li></ul><ul><li>Biodiesel is made up of various methyl esters </li></ul><ul><ul><li>- All of which break down over time </li></ul></ul><ul><li>Biodiesel is “biodegradable” </li></ul><ul><ul><li>- This is a good thing for the environment! </li></ul></ul><ul><ul><li>- But this instability can also result in operational problems in fuels </li></ul></ul>
  • 5. Transesterification of Triglycerides Why is biodiesel unstable? Why is stability important? Managing biodiesel stability The type of fatty acid (R, R ’ , R ’’ ) making up the triglyceride will vary with the feedstock CH 3 -OH Triglyceride (soy oil) Methanol + Catalyst Mixed Methyl Esters (FAME or Biodiesel) + Glycerin R’-CH 2 R-CH R’’-CH 2 CH 2 -OH CH-OH CH 2 -OH O R-O-CH 3 O R’-O-CH 3 O R’’-O-CH 3
  • 6. Different Feed Stocks Contain Different of Triglycerides Why is biodiesel unstable? Why is stability important? Managing biodiesel stability Stearic Fatty Acid Palmitic Fatty Acid CH 2 Linoleic Fatty Acid CH 2 Linoleic Fatty Acid Linoleic Fatty Acid CH 2 Oleic Fatty Acid CH 2 The type of fatty acids in the feedstock affects the stability of the biodiesel Stearic Fatty Acid Palmitic Fatty Acid CH 2 Oleic Fatty Acid CH 2 C H C H C H Palmitic Fatty Acid Palmitic Fatty Acid CH 2 Stearic Fatty Acid CH 2 C H
  • 7. Methyl Ester Make Up Determines Stability Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability Methyl Ester Name # of Carbons # of Unsaturated Bonds Relative Oxidation Stability Palmitate 16 Zero High Stearate 18 Zero High Palmitoleate 16 1 Medium Oleate 18 1 Medium Linoleate 18 2 Low Linolenate 18 3 Low
  • 8. Feedstock Choice <ul><li>Biodiesel feedstock will vary in degree of Hydrogen Saturation (or the number of double bonds) </li></ul><ul><li>The # of carbon atoms and double bonds affect: </li></ul><ul><ul><li>The natural oxidation stability of the biodiesel </li></ul></ul><ul><ul><li>And the response to anti-oxidants </li></ul></ul>Why is biodiesel unstable? Why is stability important? Managing biodiesel stability
  • 9. Biodiesel Stability Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 10. Biodiesel Stability Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability European Spec USA Spec
  • 11. Unsaturated Bonds  Instability <ul><li>Oxidative instability begins with an initial chain reaction: RH -&gt; R• </li></ul><ul><li>Followed by a propagating reaction that involves unstable peroxides and hydro-peroxides: </li></ul><ul><li>R• + O 2 -&gt; RO 2 • ROO• + RH -&gt; R-OOH + R• </li></ul><ul><li>Followed by the termination reactions resulting in aldehydes, alcohols and carbonic acids: </li></ul><ul><li>R• + R• -&gt; R-R ROO• + R• -&gt; R-OO-R </li></ul><ul><li>The reaction products also will polymerize and form sludge, sediment, varnish &amp; lacquer </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability KEY POINT: Oxidation catalyzes more oxidation!
  • 12. Instability Creates More Instability <ul><li>The Cycle of Radical Induced Oxidation </li></ul><ul><li>KEY POINT: Oxidation catalyzes more oxidation! </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 13. Other Factors <ul><li>Biodiesel contains natural anti-oxidants such as tocopherols </li></ul><ul><ul><li>Tallow and palm oils tend to be more naturally stable than soy oil </li></ul></ul><ul><li>Excess water will decrease oxidation stability </li></ul><ul><ul><li>Water can be entrained in biodiesel by: </li></ul></ul><ul><ul><ul><li>Free fatty acids (FFA) </li></ul></ul></ul><ul><ul><ul><li>Soaps formed by FFA &amp; excess caustic </li></ul></ul></ul><ul><ul><ul><li>Free glycerin and MAG, DAG &amp; TAG </li></ul></ul></ul><ul><li>Air entrainment will decrease oxidation stability </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 14. Other Factors Sterol Glucosides <ul><li>SG ’ s occur naturally in vegetable oils and animal fats but are initially soluble </li></ul><ul><ul><li>During the biodiesel manufacturing process, SG ’ s become insoluble (acylated to non-acylated form) </li></ul></ul><ul><li>As little as 30 ppm of SG’s can result in filter plugging complaints, </li></ul><ul><ul><li>SG problems are sometimes mistaken for stability problems: Both plug filters </li></ul></ul><ul><ul><li>Anti-oxidants will not remove SG’s or prevent filter plugging by SG’s </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 15. Other Factors Sterol Glucosides <ul><li>See technical paper: “ The Role of Sterol Glucosides on Filter Plugging”, </li></ul><ul><ul><li>by ADM’s Inmok Lee, Lisa M. Pfalzgraf, George B. Poppe, Erica Powers and Troy Haines, Biodiesel Magazine, April 2007 </li></ul></ul><ul><ul><li>http://www.biodieselmagazine.com/article.jsp?article_id=1566 </li></ul></ul><ul><ul><ul><li>Use Google: SG+ADM+Biodiesel+Magazine </li></ul></ul></ul><ul><ul><li>Currently, SG’s can only be removed via filtration through diatomaceous earth. See the paper above for more information. </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 16. Other Factors <ul><li>Petro diesel fuel solvency </li></ul><ul><ul><li>Hydrotreating to remove sulfur makes petro diesel a poorer solvent for sludges sediments varnishes and laquers </li></ul></ul><ul><ul><li>What remained soluble before, may not be soluble in the future! </li></ul></ul><ul><li>Sunlight: Do not store biodiesel in anything that light can penetrate such as polyethylene plastic totes </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability But why all this concern over stability?
  • 17. It’s All About Customer Satisfaction! <ul><li>Biodiesel oxidation results in: </li></ul><ul><ul><li>Sludges, sediments and laquers that: </li></ul></ul><ul><ul><ul><li>Change fuel color from light to dark </li></ul></ul></ul><ul><ul><ul><li>Clog fuel filters and injectors </li></ul></ul></ul><ul><ul><ul><li>Collect in tank bottoms </li></ul></ul></ul><ul><ul><ul><li>Lead to other problems such as corrosion </li></ul></ul></ul><ul><ul><li>Unplanned down time </li></ul></ul><ul><ul><li>Excess maintenence cost </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 18. It’s All About Customer Satisfaction! Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability Paraphrased from Robert Bosch Corp. comments @ California Energy Commission, Bioenergy Action Plan Workshop, March 9, 2006 http://www.energy.ca.gov/bioenergy_action_plan/documents/2006-03-09_workshop/2006-03-09_ROBERT_BOSCH.PDF Instability Product Cost to Equipment Cost to Customer Insoluble Polymers: sludge &amp; sediment <ul><li>Filter Plugging </li></ul><ul><li>Deposits on injector and in fuel system </li></ul><ul><li>Seizure of moving parts </li></ul><ul><li>Stalling, No Start </li></ul><ul><li>Increased smoke </li></ul><ul><li>Decreased Fuel Economy </li></ul>Soluble Polymers - Lacquer formation inside injector cylinder <ul><li>Stalling, No Start </li></ul><ul><li>Increased cost </li></ul>Acids <ul><li>Corrosion of metal parts </li></ul><ul><li>Soap formation with metal ions </li></ul><ul><li>Unnecessary costs </li></ul><ul><li>Stalling, No Start </li></ul>Peroxides Embrittlement of elastomers <ul><li>Fuel leaks </li></ul><ul><li>Unplanned downtime </li></ul>
  • 19. <ul><li>Biodiesel instability can also affect the engine oil </li></ul><ul><ul><li>Biodiesel has higher viscosity, density &amp; surface tension  more “fuel blow by” </li></ul></ul><ul><ul><li>Resulting in dilution of the lubricant by the fuel: </li></ul></ul><ul><ul><ul><li>More sludge in lubricant; More friction </li></ul></ul></ul><ul><ul><ul><li>Increased costs! </li></ul></ul></ul><ul><ul><li>See Lubes &amp; Greases Magazine, June 2007 </li></ul></ul><ul><ul><ul><li>www.LNGPublishing.com </li></ul></ul></ul>It’s All About Customer Satisfaction Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 20. It’s All About Customer Satisfaction Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability So how do we manage fuel stability? <ul><li>The fuel business is a high volume, low margin business! </li></ul><ul><li>Fuel quality must be right ALL THE TIME! </li></ul><ul><ul><li>Never give the customer a reason to blame your fuel for a problem </li></ul></ul><ul><ul><li>Even minor equipment failure can lead to large liability for the fuel supplier </li></ul></ul><ul><ul><ul><li>Tow charges, lost wages, demurrage </li></ul></ul></ul><ul><ul><li>Fuel customers have long memories </li></ul></ul>
  • 21. <ul><li>Many soy based biodiesels have high stability initially, i.e. 5+hrs Rancimat </li></ul><ul><ul><li>Do not be fooled </li></ul></ul><ul><ul><li>This good stability rating can drop significantly in a short period of time </li></ul></ul><ul><ul><li>Plugged fuel filters are the most common all season biodiesel complaint in the USA </li></ul></ul><ul><li>There are several mechanical and operational issues that can affect biodiesel oxidation stability </li></ul>1 st , Recognize Stability is an Issue with all Biodiesel Fuels Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 22. <ul><li>You must manage fuel stability: </li></ul><ul><li>Mechanically, </li></ul><ul><li>Operationally and </li></ul><ul><li>Chemically </li></ul>1 st , Recognize Stability is an Issue with all Biodiesel Fuels Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 23. Mechanical Solutions <ul><li>Add N 2 blanketing capability to storage tanks and rail cars </li></ul><ul><ul><li>Expensive “up front” but offers good “ROI” </li></ul></ul><ul><li>Design process and storage tanks and loading systems with bottom fill </li></ul><ul><ul><li>Minimize air entrainment </li></ul></ul><ul><li>Never expose biodiesel to copper, zinc or any yellow metal alloys </li></ul><ul><ul><li>These metals act as oxidation catalyst </li></ul></ul><ul><ul><li>Double check the metal used in your steam coils </li></ul></ul><ul><ul><li>Remove all galvanized pipe and fittings </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 24. Mechanical Solutions <ul><li>Paint storage tanks white to reduce temperature </li></ul><ul><ul><li>Always block any sunlight exposure </li></ul></ul><ul><li>Install water sumps on all storage tanks </li></ul><ul><ul><li>Regularly check for and remove water and check for biological growth </li></ul></ul><ul><li>Install desicant breathers to reduce condensation in storage tanks </li></ul><ul><li>Drain, clean and inspect storage tanks at least every 5 years </li></ul><ul><ul><li>SG’s are known to collect in storage tank bottoms, especially after cool weather </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 25. Mechanical Solutions <ul><li>Choose biodiesel resistant elastomers </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 26. Mechanical Solutions <ul><li>Buy new storage tanks or clean used tanks very thoroughly before use </li></ul><ul><ul><li>Biodiesel will quickly remove old petro diesel sludges, sediments, laquers &amp; varnish and put that “gunk” in your fuel </li></ul></ul><ul><ul><ul><li>And into your customers fuel filter! </li></ul></ul></ul><ul><ul><ul><li>Pro-actively warn customers about this </li></ul></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability Let me show you an example
  • 27. Mechanical Solutions Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability Biodiesel will clean petro diesel “gunk” from used fuel systems Fuel filters from Dodge pickup truck with ~ 32,000 km, burning it’s first B33 w ULSD From km 320 to km 640 New From km 130 to km 320 From km 1 to km 130 What else can you do? ( Photo courtesy of Tri-City Energy Biodiesel)
  • 28. Operational Solutions <ul><li>Give your self some room for error! </li></ul><ul><li>Stability, as measured by the Rancimat test, has significant test error: </li></ul><ul><ul><li>Repeatability +/- 5 % </li></ul></ul><ul><ul><li>Reproducibility +/- 11% </li></ul></ul><ul><ul><li>Recommend discarding used sample reaction tube glassware after each test </li></ul></ul><ul><li>Rancimat stability can quickly decrease: </li></ul><ul><ul><li>20-40% in 2-3 weeks of air and light exposure at room temperature </li></ul></ul><ul><ul><li>10-20% in a open bottle on a lab bench in just 2 weeks </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 29. Operational Solutions <ul><li>Minimize water contamination </li></ul><ul><ul><li>Maintain low FFA, glycerin, and soap </li></ul></ul><ul><li>Consider a “bio-filter” to remove SG’s </li></ul><ul><ul><li>Check for SG’s via the “filter blocking tendency test” (FBT)—ASTM Method D 2068 </li></ul></ul><ul><li>If you install vacuum distillation or cation exchange drying resin </li></ul><ul><ul><li>Remember these systems will remove natural anti-oxidants </li></ul></ul><ul><ul><li>These systems can solve other major issues so they still may be good choices </li></ul></ul><ul><ul><ul><li>But they will reduce biodiesel stability! </li></ul></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability What about anti-oxidant?
  • 30. Chemical Solutions <ul><li>Many good anti-oxidants are available </li></ul><ul><li>Some anti-oxidants may be effective but may cause color changes: </li></ul><ul><ul><li>A big issue in the USA and Canada </li></ul></ul><ul><ul><ul><li>Red dye is used to denote sulfur and tax status </li></ul></ul></ul><ul><li>Performance is influenced by the feed stock chemistry (tallow vs soy) </li></ul><ul><ul><li>What works well in soy may not work well in beef tallow or sunflower </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 31. Chemical Solutions <ul><li>“ Best practice” is to add small amount of oxidation inhibitor every day </li></ul><ul><ul><li>Even when initial stability is above required minimum </li></ul></ul><ul><ul><li>This is critical if storage tanks have no N 2 blanketing </li></ul></ul><ul><li>Apply anti-oxidants as early as possible to new biodiesel </li></ul><ul><ul><li>Anti-oxidants will not remove existing oxidation damage </li></ul></ul><ul><ul><li>Effectiveness is always better in new fuel </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 32. Chemical Solutions <ul><li>When choosing an oxidation inhibitor check for: </li></ul><ul><ul><li>Fuel additive registration requirements in the country where the biodiesel will be used </li></ul></ul><ul><li>Most countries restrict usage of fuel additive chemistries or require prior additive/fuel registration </li></ul><ul><ul><li>USA requires all CHONS components </li></ul></ul><ul><ul><li>Canadian DSL list can be challenging </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 33. Chemical Solutions <ul><li>Some anti-oxidants have cold flow or crystalization concerns </li></ul><ul><ul><li>Even as high as 10 o C. </li></ul></ul><ul><li>Flammability may be a concern </li></ul><ul><li>Good mixing is always desired </li></ul><ul><ul><li>Inject upstream of a biodiesel pump </li></ul></ul><ul><li>Anti-oxidant treat rate control is vital! </li></ul><ul><ul><li>Too low, results in poor stability </li></ul></ul><ul><ul><ul><li>Customer complaints </li></ul></ul></ul><ul><ul><ul><li>Producer liability </li></ul></ul></ul><ul><ul><li>Too high, results in excessive costs </li></ul></ul><ul><ul><li>Ask your inhibitor supplier to help </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 34. Chemical Solutions <ul><li>Regularly monitor and report oxidation stability </li></ul><ul><ul><li>Analyze trends </li></ul></ul><ul><ul><li>Indentify &amp; solve root cause of deviation </li></ul></ul><ul><ul><li>Recognize potential need to change treat rate target </li></ul></ul><ul><ul><ul><li>Change in feedstock (soy to soy/tallow blend) </li></ul></ul></ul><ul><li>Regularly monitor and report oxidation inhibitor usage vs target </li></ul><ul><ul><li>Analyze trends </li></ul></ul><ul><ul><li>Indentify &amp; solve root cause of devation </li></ul></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 35. Chemical Solutions <ul><li>Make oxidation stability a priority! </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 36. Chemical Solutions <ul><li>Make inhibitor treat rate control a priority in your plant! </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 37. Chemical Solutions <ul><li>Make inhibitor treat rate control a priority in your plant! </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 38. Summary <ul><li>Biodiesel is much more unstable than petro diesel </li></ul><ul><li>This instability can result in quality complaints and significant liability for biodiesel producers and resellers </li></ul><ul><li>Biodiesel stability can be efficiently managed through mechanical, operational and chemical best practices </li></ul><ul><li>The biodiesel producer must recognize stability as a priority! </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 39. Questions and Comments <ul><li>The biodiesel industry is new to us all </li></ul><ul><li>No producer, marketer or vendor has all the answers </li></ul><ul><li>Please share your experience and knowledge with the group...... </li></ul>Why biodiesel Is unstable? Why is stability important? Managing biodiesel stability
  • 40. Biodiesel ….. It’s Time Has Come Gracias!

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