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Consequences of fuel adulteration

Discussion in 'Tech, Gadgets & Science Forum' started by Ndahani, Jun 11, 2010.

  1. Ndahani

    Ndahani JF-Expert Member

    Jun 11, 2010
    Joined: Jun 3, 2008
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    Adulteration of transport fuel, which is currently a very flourishing business in our country, can lead to economic losses, increased emissions and deterioration of performance and parts of engines using the adulterated fuels. Some of the effects of adulteration are outlined below:
    » Mal-functioning of the engine, failure of components, safety problems etc. The problem gets further magnified for high performance modern engines.
    » Increased tailpipe emissions of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), particulate matter (PM) and can also cause increased emissions of air toxin substances.
    » Adulteration of fuel can cause health problems directly in the form of increased tailpipe emissions of harmful & sometimes carcinogenic pollutants. While indirectly in the form of diversion of PDS kerosene to the diesel sector for adulteration, thus prompting the use of biomass as domestic fuel which in turn leads to health problems of various types due to indoor air pollution. It may be noted that all forms of adulteration are not harmful to public health. Some adulterants increase emission of harmful pollutants significantly, whereas others have little or no effect on air quality.
    » Significant loss of tax revenue: - Various estimates have been made of the extent of financial loss to the national exchequer as well as the oil companies as a result of diversion of PDS kerosene, use of off-spec, low value, hydrocarbons mixed with petrol and diesel, evasion of sales tax etc. Although these estimates vary over a wide range, it is safe to assume that the nation is losing at least Rs. 10,000 crores annually as a result of adulteration of fuel.
    Adulteration & Emissions
    Fuel adulteration causes marked effect on the tailpipe emissions of vehicles, as adulterants alter the chemistry of the base fuel rendering its quality inferior to the required commensurate fuel quality for the vehicles. This in turn affects the combustion dynamics inside the combustion chamber of vehicles increasing the emissions of harmful pollutants significantly. In some cases effects of adulteration are indirect- for example, large scale diversion of rationed kerosene subsidized for household use to the diesel sector for mixing with diesel not only hamper engine performance of diesel vehicles, but also deprives the poor of kerosene which can otherwise be used for cooking and as a consequence of lack of availability of subsidized kerosene force the poor to continue to use biomass which expose them to high levels of indoor pollution.
    In general fuel adulteration can increase the tailpipe emissions of hydrocarbons (HC), carbon monoxide (CO), Oxides of nitrogen (NOx) and particulate matter (PM). Adulteration of fuels can also cause emissions of air toxins like benzene and polyaromatic hydrocarbons (PAHs) both well-known carcinogens.
    Impacts due to Gasoline Adulteration
    Adulterating gasoline with kerosene causes increase in emissions, as kerosene is more difficult to burn than gasoline and this results in higher levels of HC, CO and PM. High sulphur contents of the kerosene can deactivate the catalyst and lower conversion of engine out pollutants. Kerosene addition may also cause fall in octane quality, which can lead to engine knocking. When gasoline is adulterated with diesel fuels, the same effects occurs but usually at lower levels of added diesel fuel. Both diesel and kerosene added to gasoline will increase engine deposit formation.
    Gasoline may also be adulterated with gasoline boiling range solvent like toluene, xylene and other aromatics. With the 'judicious" adulteration, the gasoline would not exhibit drivability problems in motor vehicles. Larger amounts of toluene and /or mixed with xylene cause some increase in HC, CO, NOx emissions, and significant increase in the level of air toxins -especially benzene - in the tailpipe exhaust. The adulterated gasoline itself could have increased potential human toxicity if frequent skin contact is allowed.
    Extremely high levels of toluene (45 % or higher) could cause premature failure of neoprene, styrene butadiene rubber and butyl rubber components in the fuel system. This has caused vehicle fires in some cases, especially in older vehicles.
    Adulteration of gasoline by waste industrial solvents is especially problematic as the adulterants are so varied in composition. They will cause increased emissions, may even cause vehicle breakdown. Even low levels of these adulterants can be injurious and costly to vehicle operation.
    For gasoline, any adulterant that changes its volatility can effect drivability. High volatility (resulting from addition of light hydrocarbons) in hot weathers can cause vapour lock and stalling. Low volatility in cold weather can cause starting problems and poor warm-up.
    Impacts due to Diesel Adulteration
    The blending of kerosene with automotive diesel is generally practiced by oil industry worldwide as a means of adjusting the low temperature operability of the fuel. This practice is not harmful or detrimental to tailpipe emissions, provided the resulting fuel continues to meet engine manufacturer's specifications (especially for viscosity and cetane number). However, high-level adulteration of low sulphur diesel fuel with higher -level sulphur kerosene can cause the fuel to exceed the sulphur maximum. The addition of heavier fuel oils to diesel is usually easy to detect because the resultant fuel will be darker than normal. Depending on the nature of these heavier fuel oils and the possible presence of additional PAHs, there could be some increase in both exhaust PM and PAH emissions

    Source: Transport Fuel Adulteration