Marine Diesel Fuel Storage Stability

Transcription

1 Marine Diesel Fuel Storage Stability The Significance of Organonitrogen Content Robert E. Morris 1, Thomas N. Loegel 2, Kristina M. Myers 1, Iwona A. Leska 1, Alison E. Metz 3 1 Nova Research, Inc. 2 Naval Research Laboratory, Chemical Sensing and Fuel Technology Code Naval Air Systems Command, Air-4.4

2 Aspects of Diesel Fuel Storage Stability Compatibility Precipitation of particulates and/or gum when blended with another fuel, typically a consequence of polarity changes Polycyclic aromatics (cracked stocks, Light Cycle Oils) Asphaltenes Existent gum Reactivity Formation of insoluble reaction products Free-radical autoxidation Acid-catalyzed addition reactions Oxidative addition reactions Gum formation in glass retain sample bottles Contamination (Compositional Anomalies) Polar high MW constituents (LCO, polycyclic aromatics) Non-polar high MW constituents (lubricants, greases) Catalytic metals (Cu, Zn) FAME (problem for Naval vessels) Unapproved additives Heteroatomic species (nitrogen, sulfur-bearing compounds) WWEC April 12,

3 Historical Precedent (1982) Diesel fuel that passed specifications at receipt, later failed in storage. ASTM D4625 Testing at 43 C Stable Fuel Weeks of Storage Total Insolubles, Filterable Particulates, Soluble Gum, Unstable Fuel Higher aromatic content Higher bromine numbers More cat. cracked stock Higher conc. alkyl pyrroles Weeks of Storage ASTM D4625 Testing at 43 C Total Insolubles, Filterable Particulates, Soluble Gum, WWEC 12 April

4 Westpac Diesel Fuel Failures Navy vessels in the Pacific reported rapid filter plugging and high particulates associated with F-76 fuel Storage facilities reported observing gum in the bottom of glass retain sample bottles that had formed in a very short period of time Reports of elevated particulates continued from vessels as well as storage locations DLA Energy and US Navy investigated possible causes for particulate formation in F-76 in storage and on vessel as well as gums formed in retain sample bottles. WWEC 12 April

5 Key Results: No observable patterns that correlate with gum formation Samples in red reported to have visible gum in glass sample bottles. Sample BASELINE SAMPLES Cu, µg/kg Total N, mg/kg Cetane Improver a, mg/kg Total N mg/kg, corr. b FAME, vol% Existent Gum, mg/100ml West Coast Refinery Retain < Gulf Coast Refinery Retain < <10 15 < DEFENSE FUEL SUPPLY POINT #1 Shipboard Sample < Tank Sample < Truck Sample < Tank Sample < DEFENSE FUEL SUPPLY POINT #2 Tank Bottom Sample <10 91 < Shipboard Sample < Tank Sample < Tank Sample < < DEFENSE FUEL SUPPLY POINT #3 Tank # < Tank # < Tank # < Tank # < Refinery sample before receipt < SHIPBOARD SAMPLES Sample with Sediment < Sample with high Copper < WWEC 12 April

6 Stable Fuel vs Unstable Fuel GC-NPD Non-Basic Nitrogen Comparison Stable Fuel Non-basic nitrogen compounds found in all fuel samples Unstable Fuel WestPac Nitrogen Content 6

7 Stable Fuel vs Unstable Fuel GC-NPD Basic Nitrogen Compounds Stable Fuel Only the unstable fuels contained basic nitrogen compounds Unstable Fuel WestPac Nitrogen Content 7

8 Summary of Organonitrogen Fractions Found in Westpac Diesel Fuel Samples BNC (Benzamines) Stable No BNC s Found Unstable All contained BNC fraction WWEC 12 April

9 Conclusions Analysis of the Westpac fuels indicated a causal relationship between the presence of basic nitrogen compounds and poor storage stability. The BNC fraction was composed of substituted benzamines, pyridines and quinones. These findings strongly suggest that the high PM contents of the Westpac fuels were a consequence of the presence of the BNC. ASTM D5304 stability testing is not always diagnostic for such marginally unstable diesel fuels, based on the fact that all the unstable Westpac fuels passed the requirements of ASTM D5304 but failed in use. WWEC 12 April

10 Recommendations Targeted analyses for BNC and NBNC content should be considered in those instances where diesel storage stability is of concern. The BNC hypothesis must be thoroughly tested with a wide variety of worldwide fuel samples before considering the development of specifications to limit organonitrogen compound content. Identification of deleterious species and/or classes Determination of allowable limits WWEC 12 April

11 Acknowledgement This work was supported by: Navy Fuels & Lubricants Crossfunctional Team through Naval Air Systems Command, Air-4.4 Defense Logistics Agency Energy Program managers Michael Meredith Joseph Dougherty WWEC 12 April