Conventional fuels

Conventional fuel sources are petroleum and coal (including lignite). Our modem way of life is intimately dependent upon fossil fuels or mineral fuels. Conventional energy sources based on petroleum and coal have proven to be highly effective drivers of economic progress, but at the same time damaging to the environment and to human health (Akella et al., 2009). 

Finding 6-10. With the possible future technology advances, all but biomass and grid-electric or photovoltaic-based electrolysis technologies could be operated at costs less than those that Americans have been willing to pay in fuel costs for driving gasoline-fueled conventional vehicles. 

To bring fuel cells to the marketplace even before hydrogen becomes a readily available fuel, conventional fuels such as natural gas for stationary applications, gasoline for transportation, and methanol for portable power may be used, if hydrogen generation from these fuels is made a part of the... 

Table 5.2 lists NHV values for a certain number of pure organic compounds while Table 5.3 gives values of NHVj and NHV for conventional motor and heating fuels. 

In the expression for heating value, it is useful to define the physical state of the motor fuel for conventional motor fuels such as gasoline, diesei fuel, and jet fuels, the liquid state is chosen most often as the reference. Nevertheless, if the material is already in its vapor state before entering the combustion system because of mechanical action like atomization or thermal effects such as preheating by exhaust gases, an increase of usefui energy resufts that is not previously taken into consideration. 

The volatility of the fuel is expressed then by the temperature levels for which the V/L ratio is equal to certain particular values for example V/L = 12, V/L = 20, V/L = 36. There are correlations between the temperatures corresponding to these vaporization ratios and the conventional volatility parameters such as the RVP and the distillation curve. 

The measurement error for conventional motor fuels is around 0.3 points and 0.7 points for the RON and the MON respectively. The RON is the characteristic more often used and more widespread than the MON moreover, when the octane number is used without reference either procedure, it is taken to be the RON. 

Most conventional regular and premium fuels have an RON between 90 and 100, while their MON is between 80 and 90. 

The gradual reduction and ultimate elimination of lead has seen considerable effort by the refiner to maintain the octane numbers at satisfactory levels. In Europe, the conventional unleaded motor fuel, Eurosuper, should have a minimum RON of 95 and a minimum MON of 85. These values were set in 1983 as the result of a technical-economic study called RUFIT (Rational Utilization of Fuels in Private Transport). A compromise was then possible between refining energy expenses and vehicle fuel consumption (Anon., 1983). 

To the refiner, the question of octane numbers in future gasolines is of primary importance because it determines the course of operations, the development or on the contrary the stagnation of such and such a process. Table 5.12 thus gives an example of the typical composition by origin and concentration of different base constituents of three grades of the most common motor fuels distributed today in Europe conventional premium gasoline at 0.15 g Pb/1, Eurosuper and Superplus. 

The cold filter plugging point (CFPP) is the minimum temperature at which a given volume of diesel fuel passes through a well defined filter in a limited time interval (NF M 07-042 and EN 116 standards). For conventional diesel fuels in winter, the CFPP is usually between —15 and —25°C. 

LPG, stored as a liquid at its saturation pressure, is vaporized and introduced as vapor in conventional spark ignition motors. These motors are not modified with the exception of their feed system. Moreover, in the majority of cases, dual fuel capabilities have been adapted, that is, the vehicle can use either LPG or liquid fuel. 

This category comprises conventional LPG (commercial propane and butane), home-heating oil and heavy fuels. All these materials are used to produce thermal energy in equipment whose size varies widely from small heaters or gas stoves to refinery furnaces. Without describing the requirements in detail for each combustion system, we will give the main specifications for each of the different petroleum fuels. 

It is mainly in cold behavior that the specifications differ between bome-heating oil and diesel fuel. In winter diesel fuel must have cloud points of -5 to -8°C, CFPPs from -15 to -18°C and pour points from -18 to 21°C according to whether the type of product is conventional or for severe cold. For home-heating oil the specifications are the same for all seasons. The required values are -l-2°C, -4°C and -9°C, which do not present particular problems in refining. 

The density of heavy fuels is greater than 0.920 kg/1 at 15°C. The marine diesel consumers focus close attention on the fuel density because of having to centrifuge water out of the fuel. Beyond 0.991 kg/1, the density difference between the two phases —aqueous and hydrocarbon— becomes too small for correct operation of conventional centrifuges technical improvements are possible but costly. In extreme cases of fuels being too heavy, it is possible to rely on water-fuel emulsions, which can have some advantages of better atomization in the injection nozzle and a reduction of pollutant emissions such as smoke and nitrogen oxides. 

The high C/H ratio for heavy fuels and their high levels of contaminants such as sulfur, water, and sediment, tend to reduce their NHV which can reach as low as 40,000 kJ/kg by comparison to the 42,500 kJ/kg for a conventional home-heating oil. This characteristic is not found in the specifications, but it is a main factor in price negotiations for fuels in terms of cost per ton. Therefore it is subject to frequent verification. 

The European regulations have set SO2 emission limits for industrial combustion systems. They range from 1700 mg/Nm for power generation systems of less than 300 MW and to 400 mg/Nm for those exceeding 500 MW between 300 and 500 MW, the requirements are a linear interpolation (Figure 5.24). To give an idea how difficult it is to meet these requirements, recall that for a fuel having 4% sulfur, the SO2 emissions in a conventional boiler are about 6900 mg/Nm this means that a desulfurization level of 75% will be necessary to attain the SO2 content of 1700 mg/Nm and a level of 94% to reach 400 mg/Nm. ... 

To estimate the effect of automobile traffic and motor fuels on ozone formation, it is necessary to know the composition of exhaust gas in detail. Figure 5.26 gives an example of a gas phase chromatographic analysis of a conventional unleaded motor fuel. 

Finally it is likely that attention will be focused on emissions of polynuclear aromatics (PNA) in diesel fuels. Currently the analytical techniques for these materials in exhaust systems are not very accurate and will need appreciable improvement. In conventional diesel fuels, emissions of PNA thought to be carcinogenic do not exceed however, a few micrograms per km, that is a car will have to be driven for several years and cover at least 100,000 km to emit one gram of benzopyrene for example These already very low levels can be divided by four if deeply hydrotreated diesel fuels are used. 

This justifies all the work undertaken to arrive at fuel denitrification which, as is well known, is difficult and costly. Moreover, technological improvements can bring considerable progress to this field. That is the case with low NO burners developed at IFF. These consist of producing separated flame jets that enable lower combustion temperatures, local oxygen concentrations to be less high and a lowered fuel s nitrogen contribution to NOj. formation. In a well defined industrial installation, the burner said to be of the low NO type can attain a level of 350 mg/Nm, instead of the 600 mg/Nm with a conventional burner. 

Simple conventional refining is based essentially on atmospheric distillation. The residue from the distillation constitutes heavy fuel, the quantity and qualities of which are mainly determined by the crude feedstock available without many ways to improve it. Manufacture of products like asphalt and lubricant bases requires supplementary operations, in particular separation operations and is possible only with a relatively narrow selection of crudes (crudes for lube oils, crudes for asphalts). The distillates are not normally directly usable processing must be done to improve them, either mild treatment such as hydrodesulfurization of middle distillates at low pressure, or deep treatment usually with partial conversion such as catalytic reforming. The conventional refinery thereby has rather limited flexibility and makes products the quality of which is closely linked to the nature of the crude oil used. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

However, this conventional method presents a certain number of limitations. In the first place, the traditional end-use property itself can be difficult to determine. Consider the cetane number for example is it a good characterization of diesel fuel with respect to its behavior in commercial diesel engines In the second place, concern for protecting the environment imposes new specifications which are often specifications linked to the composition of products very low content of certain contaminants, reduced levels of certain families of compounds, or even a specific compound as already discussed. 

The conventional electrochemical reduction of carbon dioxide tends to give formic acid as the major product, which can be obtained with a 90% current efficiency using, for example, indium, tin, or mercury cathodes. Being able to convert CO2 initially to formates or formaldehyde is in itself significant. In our direct oxidation liquid feed fuel cell, varied oxygenates such as formaldehyde, formic acid and methyl formate, dimethoxymethane, trimethoxymethane, trioxane, and dimethyl carbonate are all useful fuels. At the same time, they can also be readily reduced further to methyl alcohol by varied chemical or enzymatic processes. 

Methanol. If methanol is to compete with conventional gasoline and diesel fuel it must be readily available and inexpensively produced. Thus methanol production from a low-cost feed stock such as natural gas [8006-14-2] or coal is essential (see Feedstocks). There is an abundance of natural gas (see Gas, natural) woddwide and reserves of coal are even greater than those of natural gas. 

Alcohol Production. Studies to assess the costs of alcohol fuels and to compare the costs to those of conventional fuels contain significant uncertainties. In general, the low cost estimates iadicate that methanol produced on a large scale from low cost natural gas could compete with gasoline when oil prices are around 140/L ( 27/bbl). This comparison does not give methanol any credits for environmental or energy diversification benefits. Ethanol does not become competitive until petroleum prices are much higher. 

A comparison of the characteristics associated with propellant burning, explosive detonation, and the performance of conventional fuels (see Coal Gas, NATURAL Petroleum) is shown ia Table 1. The most notable difference is the rate at which energy is evolved. The energy Hberated by explosives and propellants depends on the thermochemical properties of the reactants. As a rough rule of thumb, these materials yield about 1000 cm of gas and 4.2 kj (1000 cal) of heat per gram of material. 

Water-in-od emulsion explosives have been made as typified by a formulation containing 20% water, 12% oil, 2% microspheres, 1% emulsifier, and 65% ammonium nitrate. The micro droplets of an emulsion explosive offer the advantage of intimate contact between fuel and oxidizer, and tend to equal or outperform conventional water-based slurries. 

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