Chapter VIII Metal Effects on Thermal Stability

Abstract

The effects of trace organic components on the thermal stability of fuels have been demonstrated in previous chapters. This chapter will deal with materials which exert effects at much lower concentrations, parts per billion (ppb) rather than parts per million (ppm). Metals dissolved in jet fuel are effective at these low concentrations because they are acting as catalysts for one or more of the chemical reactions involved in the sequence of insolubles formation. Metals are a fact of life for jet fuels, however, since refinery equipment, transportation equipment, storage tanks, and aircraft fuel systems are constructed from metals. In many cases the metals are chosen for these uses on the basis of material properties and economy rather than possible degradation of thermal oxidation stability or other important fuel properties.

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

“…Copper Concentration/Storage Effect. Although the effect of copper is reported to be catalytic, , increases in concentrations at low copper levels have been known to increase thermal deposits . For the fuels examined, increases in total thermal deposits due to a combined copper concentration/storage effect are shown in Table .…”

“…Dissolved copper has been found to be the most reactive of the metals that catalyze fuel oxidation. , Consequently, due to the 90:10 copper−nickel (Cu−Ni) alloy used in the fuel piping systems of U.S. aircraft carriers and air capable ships, , copper contamination of JP-5 fuels is of particular interest to the U.S. Navy. From a commercial standpoint, copper contamination can also occur from other sources including the refinery copper sweetening process, the copper bearings used in fuel pumps, and from the copper heating coils in many multipurpose tankers that are used to transport jet fuels. The adverse effects of metals, including copper, on jet fuel thermal stability have been reviewed by Nowack 6 and later by Hazlett .…”

“…From a commercial standpoint, copper contamination can also occur from other sources including the refinery copper sweetening process, the copper bearings used in fuel pumps, and from the copper heating coils in many multipurpose tankers that are used to transport jet fuels. The adverse effects of metals, including copper, on jet fuel thermal stability have been reviewed by Nowack 6 and later by Hazlett . As indicated in the reviews, , the deleterious effects of copper on fuel thermal stability are dependent on the fuel and the solubilized copper concentration.…”

“…The adverse effects of metals, including copper, on jet fuel thermal stability have been reviewed by Nowack 6 and later by Hazlett . As indicated in the reviews, , the deleterious effects of copper on fuel thermal stability are dependent on the fuel and the solubilized copper concentration.…”

Autoxidation of Neat and Blended Aviation Fuels

“…Fouling of the inner heated surfaces of fuel passages that are exposed to liquid/gaseous fuel or combustion products has been successfully reduced in both automotive and aviation fuels by the introduction of low-cost additives. Additives have also been used in aviation fuels to slow oxidation, reduce corrosion, prevent freezing and buildup of static charge, and reduce agglomeration of insolubles .…”