Vanadium diesel fuel

The ash-forming constituents in diesel fuel (ASTM D-2880) are typically so low that they do not adversely affect gas turbine performance, unless such corrosive species as sodium, potassium, lead, or vanadium are present. However, there are recommendations for the storage and handling of these fuels (ASTM D-4418) to minimize potential contamination. 

The present trend in the petroleum industry shows an increasing demand for light products such as gasoline, jet fuel and diesel fuel. In order to meet the market demand, refineries convert a portion of their residual heavy oils into light fractions by destructive processes as was highlighted in chapter 6. This conversion also results in the production of modem heavy fuels, which contain a greater concentration of sulfur, vanadium, and asphaltenes. 

Magnesium additives combine with the vanadium to form salts that deposit onto the blade surfaces. When the turbine is shut down, the salts fall off with the drop in temperature. The remaining salts are washed off with plain water. Typically, the wash is done every 100 operating hours for heavy oil. If gas or diesel fuel are used, no wash is required. 

A high-nickel alloy is used for increased strength at elevated temperature, and a chromium content in excess of 20% is desired for corrosion resistance. An optimum composition to satisfy the interaction of stress, temperature, and corrosion has not been developed. The rate of corrosion is directly related to alloy composition, stress level, and environment. The corrosive atmosphere contains chloride salts, vanadium, sulfides, and particulate matter. Other combustion products, such as NO, CO, CO2, also contribute to the corrosion mechanism. The atmosphere changes with the type of fuel used. Fuels, such as natural gas, diesel 2, naphtha, butane, propane, methane, and fossil fuels, will produce different combustion products that affect the corrosion mechanism in different ways. 

These are the nonbumable components, typically metals and metalloids, found in fuel. Depending upon size, these particles can contribute to fuel system wear and filter and nozzle plugging. Sodium, potassium, lead, and vanadium can cause corrosion of certain high-temperature alloys such as those found on diesel engine valves and gas turbine blades. 

R. E. Santelli, M. A. Becerra, A. S. Freire, E. P. Oliveira and A. F. Batista-de-Carvalho, Non-volatile vanadium determination in petroleum condensate, diesel and gasoline prepared as detergent emulsions using GFAAS, Fuel, 87(8-9), 2008, 1617-1622. 

There is considerable overlap in the boiling ranges of the diesel, jet, kerosene, and light fuel oils represented by the distillate fuel oil class. All, if desulfurized, have the capability of burning relatively cleanly with little more than a trace of ash as a residue. The ash consists of transition metal oxides (mainly vanadium). 

Crude residual components (called resid) contain metals such as nickel and vanadium. These metals, especially the nickel, accumulate on the cracking plant zeolite catalyst. The nickel promotes hydrothermal reactions in the FCCU (or "Cat"). Such reactions preferentially produce low-value fuel gas and catalytic coke, consequently reducing the production of more valuable diesel oil and gasoline. Flence, black gas oil downgrades a refinery s ability to produce motor fuels. 

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