Nickel vanadium

Other heavy fuel contaminants are metals (vanadium, nickel, sodium) coming from the crude oil itself or metallic salts (aluminum silicates) coming from catalysts in conversion steps. The aluminum silicates should not exceed 300 ppm (30 ppm of aluminum), for these materials exert a strong abrasive action on the engine cylinders and injection systems. They can however be eliminated partially by centrifuging and filtration. 

Other compounds which may be found in crude oil are metals such as vanadium, nickel, copper, zinc and iron, but these are usually of little consequence. Vanadium, if present, is often distilled from the feed stock of catalytic cracking processes, since it may spoil catalysis. The treatment of emulsion sludges by bio-treatment may lead to the concentration of metals and radioactive material, causing subsequent disposal problems. 

Metals in the platinum family are recognized for their ability to promote combustion at lowtemperatures. Other catalysts include various oxides of copper, chromium, vanadium, nickel, and cobalt. These catalysts are subject to poisoning, particularly from halogens, halogen and sulfur compounds, zinc, arsenic, lead, mercury, and particulates. It is therefore important that catalyst surfaces be clean and active to ensure optimum performance. 

The presence of asphaltenes, originating in the fuel, acts as a trap for vanadium, nickel, and sodium (which promote slagging and sulfur corrosion)-, these asphalthenes often contain sulfur compounds, which simply add to the contaminant load. Additionally, asphaltenes act as precursors to spherical stack solids (cenospheres), which are exhausted with the flue gases as stack emissions. 

Heavy fuel oils may contain a relatively high level of noncombustible materials that result in considerable ash formation. Oils containing more than 0.05% ash are considered high-ash fuels, whereas oil containing less than 0.02% ash are considered low-ash fuels. Vanadium, nickel, sodium, iron, and some other catalytic metals form the greatest proportion of the ash content. 

The degree of slagging, is, in turn, closely related to the concentration of vanadium, nickel, and sodium compounds present in the fuel, and the types of low melting-point oxides and complex sticky deposits formed under specific boiler temperatures and prevailing conditions. These deposits are difficult to remove online with soot blowers, but... 

Known to be essential, but function unknown Silicon, vanadium, nickel, tin... 

Alves et al. [744] determined vanadium, nickel, and arsenic in seawater in the 10-20 000 ppt range using flow injection cryogenic desolvation ICP-MS. 

Brunnock et al. [67] have also determined beach pollutants. They showed that weathered crude oil, crude oil sludge, and fuel oil can be differentiated by the n-paraffin profile as shown by gas chromatography, wax content, wax melting point, and asphaltene content. The effects of weathering at sea on crude oil were studied parameters unaffected by evaporation and exposure are the contents of vanadium, nickel, and n-paraffins. The scheme developed for the identification of certain weathered crude oils includes the determination of these constituents, together with the sulfur content of the sample. 

Hodgson, G. W., 1954, Vanadium, Nickel and Iron Trace Metals in Crude Oils of Western Canada American Association of Petroleum Geologists Bulletin, Vol. 38, pp. 2537-2554. 

In addition to hydrocarbons, petroleum also contains compounds that consist of nitrogen, oxygen, and sulfur (in the minority) as well as trace amounts of metals such as vanadium, nickel, iron, and copper. Porphyrins, the major organometaUic compounds present in petroleum, are large, complex cyclic carbon structures derived from chlorophyll and characterized by the ability to contain a central metal atom (trace metals are commonly found within these compounds). 

In ash and soot residues from Orimulsion-lired power stations, the dominating metal constituents are vanadium, nickel, and iron, together with... 

The essential microelements are only required in trace amounts (see also p.2). This group includes iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), cobalt (Co), chromium (Cr), selenium (Se), and molybdenum (Mo). Fluorine (F) is not essential for life, but does promote healthy bones and teeth. It is still a matter of controversy whether vanadium, nickel, tin, boron, and silicon also belong to the essential trace elements. 

Anyone who is seriously involved in catalytic cracking, whether as an operator, a catalyst manufacturer, or a researcher, soon learns how severely sodium, vanadium, nickel, iron, and copper act as poisons. In the past, FCC feedstock preparation via vacuum distillation was to a considerable extent, determined by metal carryover. Generally, metal carryover to the fluid unit was limited to 0.1 ppm or less of each of these metals. 

Crude oil is composed primarily of hydrocarbon compounds. Organic and inorganic sulfur-, oxygen-, and nitrogen-containing species are also found in crude oil. Additionally, water, vanadium, nickel, sodium, and other metals may be present. 

The major contaminating metals found on catalytic cracking catalyst are vanadium, nickel, copper, chromium, and iron. Small amounts of these metals are present in the crude petroleum and, except for some of the iron, all are in the form of metal-organic compounds. Some of these compounds are volatile and when the vacuum gas oil feed to the catalytic cracking units is prepared, they appear in the gas oil. A fraction of the iron, and probably chromium, found on the catalyst is the result of erosion and corrosion either in the lines or in the equipment. 

When the data for vanadium, nickel, cobalt, copper, and iron in petroleum of the Western Interior Region (15) shown below are divided by the average crustal abundance of these elements, the relation, V>Ni>Co>Cu>Fe is... 

Where the valency of a metal is not indicated, the normal valency of the metal is assumed. Beryllium probably is placed in the 0=N group because of the stability of its phthalocyanine chelate. Most often Be forms very stable bonds with oxygen as the donor element. Vanadium, nickel, and copper from the N > O group and iron from the ON group are the elements most frequently found in petroleum, chelated with porphyrin ligands. The porphyrin chelate contains four nitrogens as donor elements. 

Figure 10. Vanadium/chromium and vanadium/nickel ratios of the top and central portions of the bed. Numbers 1-9 indicate samples taken from localities shown in Figure 9. Solid line are vanadium/chromium ratios, dashed line vanadium/nickel ratios. Stipled areas of columnar samples were not analyzed...

Sometimes, deposits accumulate on the exterior of tubes. These deposits are unavoidable when heavy industrial fuel oil is fired.Such fuel oils contain high concentrations of vanadium, nickel, sodium, and iron (in that order of concentration). These metals deposit as an ash, on the exterior of both the radiant- and convective-section tubes. The ash will get very hot and will turn sections of tubes yellow, or even whitish silver. This is not an indication of tube overheating. If the deposits get thick enough, they will interfere with the rate of heat absorption by the tube. It is very difficult to distinguish between a real hot spot and glowing ash. Dirty fuel gas also leads to ash formation on the radiant surface of tubes. 

Other factors indicated m the data of Tables 1 and 2 include Pour Point—defined as the lowest temperature at which the material will pour and a function of the composition of the oil in terms of waxiness and bitumen content Salt Content—which is not confined to sodium chloride, but usually is interpreted in terms of NaCl Salt is undesirable because of the tendency to obstruct fluid flow, to accumulate as an undesirable constituent of residual oils and asphalts, and a tendency of certain salt compounds to decompose when heated, causing corrosion of refining equipment Metals Content—heavy metals, such as vanadium, nickel, and iron, tend to accumulate in the heavier gas oil and residuum fractions where the metals may interfere with refining operations, particularly by poisoning catalysts. The heavy metals also contribute to the formation of deposits on heated surfaces in furnaces and boiler fireboxes, leading to permanent failure of equrpment, interference with heat-transfer efficiency, and increased maintenance. 

Crude Wt. % Sulfur Wt. Nitrogen % of total Vanadium Nickel TGA residue (% of fraction) H/C... 

Distillation concentrates the metallic constituents in the residua (Table 3-5) some can appear in the higher-boiling distillates but the latter may, in part, be due to entrainment. Nevertheless, there is evidence that a portion of the metallic constituents may occur in the distillates by volatilization of the organometallic compounds present in the petroleum. In fact, as the percentage overhead obtained by vacuum distillation of reduced crude is increased, the amount of metallic constituents in the overhead oil is also increased. The majority of the vanadium, nickel, iron, and copper in residual stocks may be precipitated along with the asphaltenes by low-boiling alkane hydrocarbon solvents. Thus, removal of the asphaltenes with n-pentane reduces the vanadium content of the oil by up to 95% with substantial reductions in the amounts of iron and nickel. 

Bache CA, Rutzke M, Lisk DJ. 1991. Absorption of vanadium, nickel, aluminum and molybdenum by Swiss chard grown on soil amended with oil fly ash or bottom ash. J Food Saf 12 79-84. 

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