Fuel oils material factor

Emissions of soot on the other hand represent a smaller fraction of the overall emission, but are probably of greater concern from the standpoint of visibility and health effects. It has been suggested that soot emissions from fuel oil flames result from processes occurring in the vicinity of individual droplets (droplet soot) before macroscale mixing of vaporized material, and from reactions in the bulk gas stream (bulk soot) remote from individual droplets. Droplet soot appears to dominate under local fuel lean conditions (1, 2), while bulk soot formation occurs in fuel rich zones. Factors which are known to affect soot formation from liquid fuel flames include local stoichiometry, droplet size, gas-droplet relative velocity and fuel properties (primarily C H ratio). 

These factors have akeady led to a substantial investment in fuel oil-desulfurization facilities in several parts of the world, notably Japan, the Middle East, and the Caribbean. With few exceptions these facilities have been based on indirect desulfurization, i,e., vacuum distillation, desulfurization of the vacuum gas oil, and reblending. This technique has limits in a market for fuels below the 1% sulfur level because none of the heavy, high sulfur vacuum residue is processed. To some extent this can be mitigated by preferentially blending this material to bunkers and by using naturally occurring low sulfur residues as blending stocks. 

Because the sulfur contained in crude oil is concentrated in the residue material, residual fuel sulfur levels naturally vary from less than 1 to over 6%. The sulfur level is not a critical factor for the combustion process as long as the flue gases do not impinge on cool surfaces. However, residual fuels may contain large quantities of heavy metals such as nickel and vanadium these produce ash upon burning and can foul the burner systems. Such contaminants are not easily removed and usually lead to lower market prices for fuel oils with high metal contents. 

The most important factor for the choice of process layout is, of course, the type of feedstock. Before the Second World War coke dominated (see Sect. 6.3.6). During the war several plants based on natural gas were constructed in the USA [522], and natural gas has since then been the preferred feedstock in the USA as well as in other parts of the world. There has, however, also been a significant production based on partial oxidation of heavy fuel oil or gasification of coal, especially in Europe and in countries like India and China also naphtha has been a preferred feedstock in some areas. During the 1970s there was, due to the oil crises, a renewed interest, especially in the USA, in coal as feedstock for ammonia production, but an expected major change to coal-based production of ammonia did not materialize. Comparisons of the economics of ammonia production from different feedstocks may be found in [160, 676-691]. 

Advances in materials science have been a leading factor contributing to improvements in vehicle fuel economy and performance since the 1973 oil embargo. Better tire materials have reduced rolling resistance, better materials for moving parts have reduced friction, and most importantly lighter body parts have reduced the overall weight of vehicles. 

At present, roughly 80% of the current global energy needs comes from fossil fuels. Besides, oil is used as a raw material for the production of several chemical products. Ethanol (C2H5OH), a natural product obtained from biomass, is, on the one hand, a renewable source of energy that would be an important factor for near-zero carbon dioxide (C02) emissions, on the other hand, it is the basis for a C2 chemistry, that is, a raw material for the production of different chemical products [19,21,137-147], Besides, ethanol is accessible, can be easily transported, biodegradable, has low toxicity, and can be transformed by catalytic reactions [137],... 

Another source of metallic contamination in the studied region comes from the residual oil combustion used for electric utilities and fluvial and terrestrial transportation. Using the selected emission factors (quantity of trace element released by quantity of material consumed) given by Nriagu and Pacyna (1988) and Nriagu (1989), the electric-power production installed in the Amazonian states and the fuel consumption used for transportation (Ministerio de Minas... 

Fuel. The best plan is to locate near large coal fields if coal is the primary fuel or to tie up by long contracts sufficient gas and/or oil to ensure the continuity of operations over a long term. The Gulf Coast area has been built up in the past 15 years largely because of plentiful and cheap gas. When gas is the basic raw material, as in ammonia synthesis, synthetic gasoline, it is the controlling economic factor as it supplies the raw materials, heat, and power. 

---