Comparison of the Effects of Storage in the Presence of Copper Using Laboratory vs Field Conditions on Jet Fuel Thermal Stability As Measured by the Gravimetric JFTOT

Abstract

The effects of storage in the presence of copper using laboratory test conditions vs field conditions on fuel thermal stability were compared using five JP-5 fuels. Laboratory test conditions refer to accelerated storage at 90 °C/50 psig of air/24 h in the presence of soluble copper from copper(II) ethyl acetoacetate (CuEA). In contrast, field conditions refer to long-term storage at room temperature (∼20 °C) in the presence of dissolved copper from 90/10 copper-nickel (Cu-Ni) alloy for a period of approximately 6 months. Thermal stabilities were determined using the gravimetric JFTOT, which gives a quantitative measure of the total deposits formed. A copper concentration/storage effect was observed, which necessitated evaluations at similar copper concentrations. However, the source of copper appears not to be important. Instead, the main operative factor affecting the thermal stability of stored fuels appears to be the combination of long-term ambient storage and the presence of copper. Good agreement was obtained between the thermal stabilities of fuels that were stored using the specified laboratory and field conditions. These results are significant because (1) they validate the use of the specified laboratory test conditions as being realistic; (2) they support our premise that precursors that lead to thermal deposits are formed on storage in the presence of copper; and (3) they offer a rigorous method for predicting the potential thermal stabilities of jet fuels.

The Development and Use of Metal Deactivators in the Petroleum Industry: A Review

“…This agrees directionally with the original MDA gasoline work, which demonstrated the limited ability of antioxidants to control peroxidation due to soluble catalytically active metals . When a JP-5 was doped with 420 ppb copper as copper(II) ethyl acetoacetate, aged 24 h in the LPR, and then additized with 5.7 ppm MDA, strip deposits were not reduced and filterable deposits were only slightly reduced relative to the same copper-doped/aged fuel without MDA. , The implication of this work is that the combination of aging in the presence of soluble copper can generate instability precursors or products. − Once these precursors or products are formed, chelation of copper may be a moot point. The damage to fuel thermal stability may already be done.…”

“…In a series of papers by Pande and Hardy, − the effect of MDA on jet fuel properties was measured using the gravimetric JFTOT. A number of Jet A, JP-5, and JP-8 fuels were tested with ambient or accelerated aging, copper treating by dopant addition or natural uptake due to prolonged exposure to metallic copper and combinations of aging and copper.…”

“…However, more recent work by Pande and Hardy, [29][30][31][32][33][34] using the gravimetric JFTOT, has shown that the combined effect of aging in the presence of dissolved copper is far larger than the sum of the individual effects of aging without dissolved copper and dissolved copper without aging. The gravimetric JFTOT is a modification of the JFTOT where the heated metal tube is replaced by a metal foil strip (usually stainless steel).…”

Effects of Extended Duration Testing and Time of Addition of N,N‘-Disalicylidene-1,2-propanediamine on Jet Fuel Thermal Stability As Determined Using the Gravimetric JFTOT

“…For study 2 , the two freshly refined fuels are identified for convenience as TX and LA based on their refinery location, which were Texas and Louisiana, respectively. Note that these are the same two fuels that were used in a previous investigation . This current study is an extension of that investigation.…”

Copper Removal from Fuel by Solid-Supported Polyamine Chelating Agents

“…In addition, significant quantities of JP-5 fuel are held in storage as unusable for aircraft use due to unacceptably high levels of copper. There is evidence that dissolved copper can promote certain prerequisite chemical reactions in jet fuel during storage, which enhance the autoxidation process and result in thermal degradation. The addition of soluble metal chelants has been the basis for present measures in counteracting the catalytic effects of dissolved copper in fuels.…”