Diesel Fuel 8urner Fuel High-Ash Typical
Kerosene #2 Oil #2 JP-4 Crude Heavy Libyan Navy Heavy Low-Ash
.esidual Crude Distillate Distillate Crude
Flash point 0 F 130/160 118-220 150/200 . RT 175/265 186 0F 198 50/200
Pour point 0F 50 55 to十10 10/30 15/95 68 10 0F 15/110
Visc. CS . 100 0F 1.4/2.2 2.48/2.67 2.0/4.0 .79 100/1，800 7.3 6.11 6.20 2/100
SSU 34.4 45.9
Sulfur % .01/.1 .169/.243 .1/.8 .047 .5/4 .15 1.01 1.075 .1/2.7
API gr. 38.1 35.0 53.2 30.5
Sp. gr. . 100 0F .78/.83 .85 .82-.88 .7543⑧60 0F .92/1.05 .84 .874 .8786 .80/.92
Water & ded. Btu 0 .1%wt
Heating value lb 19，30 0/19，70 0 18，33 0 19， 000/19， 600 18，70 0/18，82 0 18，300/18， 900 18，250 18，23 9 19，000/19，400
Hydrogen % 12.8/14.5 12.83 12/13.2 14.75 10/12.5 12.40 12/13.2
Carbon residue .01/.1 .104 .03/.3 2/10 .3/3
10% bottoms
Ash ppm 1/5 .001 0/20 100/1，000 36ppm 20/200
Na十 K ppm 01.5 0/1 1/350 2.2/4.5 0/50
V 0/.1 0/.1 5/400 0/1 0/15
Pb 0/.5 0/1 0/25
Ca 0/1 0/2 0/2 0/50
.ue.s 44.
Finally， the weight of afuel， light orheavy， refers to volatility. The most volatile fuels vaporize easily and come out early in the distillation process. Heavy distillates will come out later in the process. What remains after distillation is referred to as residual. The ash content of residual fuels is high.
Catastrophic oxidation requires the presence of Na2SO4and Mo，W， and/or V. Crude oils are high in V; ash will be 65% V2O5 or higher. The rate at which corrosion proceeds is related to temperature. At temperatures of more than 1500 0F， attack by sulfidation takes place rapidly. At lowertemperatures with vanadium-rich fuels， oxidation catalyzed by vanadium pentoxide can exceed sulfidation. The effect of temperature on IN 718 corrosion by sodium and vanadium is shown in Figure 12-3. The corrosive threshold is generally accepted to be in the range of 1100-1200 0F， (593-649 0C) and this cannot be considered a feasible firing temperature due to losses in efficiency and power output. Figure 12-4 shows the effect of sodium
Figure 12-3. The effect o. temperature on .N .1. corrosion by sodium and .anadium.
Figure 12-4. Effect o. sodium. potassium. and .anadium on combustor .ife.
plus potassium and vanadium on life. Allowable limitsfor100%，50%，20%， and 10% of normal life with uncontaminated fuel at standard firing temperatures are shown.
Fuel Treatment
Natural gas requires no fuel treatment; however， low-Btugas， especiallyif derived from various coal gasification processes， requires various types of cleaners for use in a gas turbine. These cycles can get very complex as indicated by atypical system， which utilizes a steam bottoming cycle to achieve high efficiency. Vaporized fuel oil gas is already cleansed of its impurities in the vaporization process.
A corrosion-inhibiting fuel treatment has been developed for the use oflower-grade liquid fuels.Sodium，potassium， and calcium compounds are most often present in fuel in the form of seawater. These compounds resultfrom salty wells and transportation over seawater， or they can be ingested by the compressor in mist form in ocean environments. Methods developed toremove the salt and reduce the sodium， potassium， and calcium rely on the water-solubility of these compounds. Removal of these compounds through their water-solubility is known as fuel washing. Fuel washing systems fallinto four categories: centrifugal， DC electric， ACelectric， and hybrids.
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