Fuel residual

The conversion takes place at high temperature (820-850°C) and very short residence time (hundredth of seconds) in the presence of steam. The by-products are hydrogen, methane and a highly aromatic residual fuel-oil. 

Residual fuel-oil represented more than 20 to 25% of the crude and the content in pollutants (sulfur, nitrogen, metals) increased. 

Residential sheathing Residual fuel Residual fuel oil Residual gas analyzers... 

Heavy oil, ie, grade nos. 4, 5, and 6, and residual fuel oils light oils, ie, no. 2 heating oil, kerosene, and jet fuel and petroleum coke are deflvered at... 

Thermal Cracking. In addition to the gases obtained by distillation of cmde petroleum, further highly volatile products result from the subsequent processing of naphtha and middle distillate to produce gasoline, as well as from hydrodesulfurization processes involving treatment of naphthas, distillates, and residual fuels (5,61), and from the coking or similar thermal treatment of vacuum gas oils and residual fuel oils (5). 

The hquid remaining after the solvent has been recovered is a heavy residual fuel called solvent-refined coal, containing less than 0.8 wt % sulfur and 0.1 wt % ash. It melts at ca 177°C and has a heating value of ca 37 MJ/kg (16,000 Btu/lb), regardless of the quaUty of the coal feedstock. The activity of the solvent is apparently more important than the action of gaseous hydrogen ia this type of uncatalyzed hydrogenation. Research has been directed to the use of petroleum-derived aromatic oils as start-up solvents (118). 

Cmde oil can be easily separated into its principal products, ie, gasoline, distillate fuels, and residual fuels, by simple distillation. However, neither the amounts nor quaUty of these natural products matches demand. The refining industry has devoted considerable research and engineering effort as well as financial resources to convert naturally occurring molecules into acceptable fuels. Industry s main challenge has been to devise new ways to meet the tremendous demand for gasoline without, at the same time, overproducing other petroleum products. 

Noncatalytic partial oxidation of residual fuel oil accounts for the remainder of world methanol production. Shell and Texaco ate the predominant hcensors for partial oxidation technology (16) the two differ principally in the mechanical details of mixing the feedstock and oxidant, in waste heat recovery, and in soHds management. 

The word distillate is occasionally used by petroleum chemists with a specialized meaning. Although anything that has been distilled is, of course, a distillate, the term distillate is sometimes used to denote distillate fuel oil as opposed to residual fuel oil. 

Visbreaking. Viscosity breaking (reduction) is a mild cracking operation used to reduce the viscosity of residual fuel oils and residua (8). The process, evolved from the older and now obsolete thermal cracking processes, is classed as mild because the thermal reactions are not allowed to proceed to completion. 

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned ia utility boilers. Coal ash ia the atmosphere also coataias vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m, whereas air samples from Los Angeles and Honolulu contained 1—12 ng V/m. Adverse pubHc health effects attributable to vanadium ia the ambieat air have aot beea deteroiiaed. lacreased emphasis by iadustry oa controlling all plant emissions may have resulted ia more internal reclamation and recycle of vanadium catalysts. An apparent drop ia consumption of vanadium chemicals ia the United States since 1974 may be attributed, in part, to such reclamation activities. 

Liquid fuels for ground-based gas turbines are best defined today by ASTM Specification D2880. Table 4 Hsts the detailed requirements for five grades which cover the volatility range from naphtha to residual fuel. The grades differ primarily in basic properties related to volatility eg, distillation, flash point, and density of No. 1 GT and No. 2 GT fuels correspond to similar properties of kerosene and diesel fuel respectively. These properties are not limited for No. 0 GT fuel, which allows naphthas and wide-cut distillates. For heavier fuels. No. 3 GT and No. 4 GT, the properties that must be limited are viscosity and trace metals. 

The pricing of carbon black feedstocks depends on their alternate market as residual fuel oil, especially that of high sulfur No. 6 fuel oil. The actual price is deterrnined by the supply/demand relationships for these two markets. Feedstock cost contributes about 60% of the total manufacturing cost. The market price of carbon black is strongly dependent on the feedstock cost as shown in Figure 8. 

Heat of combustion can be estimated within 1 percent from the relative density of the fuel by using Fig. 27-3. Corrections for water and sediment must be apphed for residual fuels, but they are insignificant for clean distillates. 

Contaminants in fuels, especially alkali-metal ions, vanadium, and sulfur compounds, tend to react in the combustion zone to form molten fluxes which dissolve the protective oxide film on stainless steels, allowing oxidation to proceed at a rapid rate. This problem is becoming more common as the high cost and short supply of natural gas and distillate fuel oils force increased usage of residual fuel oils and coal. 

In general terms, the life of a combustor might be reduced by about 30 percent through use of a distillate fuel and by 80 percent through the use of residual fuel. The first stage turbine nozzle life can Be reduced by 20 percent through use of a distillate fuel and by about 6.5 percent when certain residual fuels are used. 

Thermal energy, power generation, and incineration have several factors in common. All rely on combustion, which causes the release of air pollutants all exhaust their emissions at elevated temperatures and all produce large quantities of ash when they consume solid or residual fuels. The ratio of the energy used to control pollution to the gross energy produced can be a deciding factor in the selection of the control system. These processes have important differences which influence the selection of specific systems and devices for individual facilities. 

A final fuels group eontains high-ash erudes and residuals. These aeeount for 5% of installed units. Residual fuel is the high-ash by-produet of distillation. Low eost makes them attraetive however, speeial equipment must always be added to a fuel system before they ean be utilized. Crude is attraetive as a fuel, sinee in pumping applieations it is burned straight from the pipeline. Table 12-2 shows data obtained from a number of users that... 

Finally, the weight of a fuel, light or heavy, refers to volatility. The most volatile fuels vaporize easily and eome out early in the distillation proeess. Heavy distillates will eome out later in the proeess. What remains after distillation is referred to as residual. The ash eontent of residual fuels is high. 

Figure 12-5. A typical residual fuel treatment system.

Early U.S. experienee in residual operation dates baek to the early 1950s. Several eompanies adapted gas turbines to run on residual fuel for loeo-motive applieation. Operating with a low inlet temperature 1350 °F (732 °C), low-sulfur residual eorrosion was limited however, it was noted that any inerease in firing temperature was aeeompanied by serious eorrosion. Beeause of the advantage of inereased firing temperatures, researeh on fuel... 

Plugged nozzle. This is indieated by an inerease in fuel pressure in eonjunetion with inereased eombustion unevenness. This is a eommon problem when residual fuels are used. 

Chemical Designations - Synonyms Residual fuel oil. No 4 Chemical Formula Not applicable. 

Chemical Designations - Synonyms Residual fuel oil. No 5 Chemical Formula Not applicable. Observable Characteristics - Physical State (asshipped) Liquid Color. Brown Odor. Like kerosine characteristic. 

---