Combustion reactions fossil fuels

Atmospheric pollutants released by combustion of fossil fuels fall into two main categories those emitted direcdy into the atmosphere as a result of combustion and the secondary pollutants that arise from the chemical and photochemical reactions of the primary pollutants (see Airpollution). 

Combustion processes are the most important source of air pollutants. Normal products of complete combustion of fossil fuel, e.g. coal, oil or natural gas, are carbon dioxide, water vapour and nitrogen. However, traces of sulphur and incomplete combustion result in emissions of carbon monoxide, sulphur oxides, oxides of nitrogen, unburned hydrocarbons and particulates. These are primary pollutants . Some may take part in reactions in the atmosphere producing secondary pollutants , e.g. photochemical smogs and acid mists. Escaping gas, or vapour, may... 

A considerable amount of work has been carried out into the corrosion of steels in the gases produced during the combustion of fossil fuel due to extensive use of low alloy steels as heat exchanger tubes in power generation. Combustion gases contain many species, such as CO, CO2, SO2, SO3, H2S and HCl, arising from elements within the fuel. The many different combinations of operating temperature and chemical stoichiometry of combustion reactions lead to many possible complex corrosion reactions. 

The principal cause of acid rain is the combustion of fossil fuels that produce sulfur and nitrogen emissions. The primary sources are electrical power plants, automobiles, and smelters. Power plants produce most of the sulfur emissions and automobiles most of the nitrogen emissions. Other sources of acid rain include nitrogen fertilizers, jet aircraft, and industrial emissions. Just as in our discussion of ozone, numerous reactions are involved in the formation of acid rain. The process can be understood by considering the transformation of sulfur and nitrogen oxides into their respective acidic forms sulfuric acid and nitric acid. Sulfur, present up to a few percent in fuels such as coal, is converted to sulfur dioxide when the fuel is burned. The sulfur dioxide reacts with water to produce sulfurous acid, H,SO ,, that is then oxidized to sulfuric... 

Sulfuric acid plays a major role in air quality and is a primary contributor to acid deposition. The combustion of fossil fuels, which contain sulfur as an impurity, results in the production of sulfur oxides. Sulfur oxides react with water in the atmosphere to produce sulfuric acid, but they may also undergo other reactions leading to dry deposition. Clean air is slightly acidic, with a pH of approximately 5.6. The acidic conditions are primarily due to the presence of carbonic acid produced from the carbon dioxide present in the atmosphere. 

The lesson to be learned from this rather coarse and simplified analysis is that spontaneous reactions are costly and energy-inefficient. The spontaneous combustion of fossil fuels for example costs about 30% of the work available in the original fuel [4]. Instead, one should aim for bridging the distance in affinity by a limited number of coupled reactions, which are sequential and share a common intermediate. 

In the first three sections, 19 chapters relate different methods that address the main options for reducing pollutants (1) removal of sulfur, ash, and trace elements prior to combustion (2) control of emissions by various techniques or adjustment of conditions during combustion and (3) cleanup of combustion effluents in various gas streams. In the last section, 10 chapters describe the characterization, reactions, transport, and effects of pollutants emitted during the combustion of fossil fuels. 

More than 140 different alkenes have been identified in the atmosphere [27]. The sources of alkenes are similar to those for the alkanes with combustion of fossil fuel being a major source. The presence of unsaturated bonds makes these compounds much more reactive than the alkanes. The most persistent member of this class of compounds (ethene) has an atmospheric lifetime of the order of a day, while more typically the lifetimes for alkenes are measured in hours. As a result of their short lifetimes the atmospheric concentrations of alkenes are highly variable and decrease dramatically away from their source locations. The mechanisms of atmospheric oxidation of alkenes have recently been reviewed [55]. As with the alkanes the reaction of OH radicals is an important loss mechanism. This reaction proceeds mainly via addition to the unsaturated bond as illustrated for ethene in Fig. 4. In one atmosphere of air at 298 K the dominant atmospheric fate of the alkoxy radical HOCH2CH2O is decomposition via C - C bond scission, while reaction with O2 makes a 20% contribution [56]. The fate of alkoxy radicals resulting from addition of OH to alkenes is generally decomposition via C - C bond scission [8]. Thus, the OH radical initiated oxidation of propene gives acetaldehyde and HCHO, oxida-... 

Combustion Reactions Combustion of Fossil Fuels and Air Pollution... 

Rain more acid than about pH 5.7 results from reactions of the acid gases SO2, NO2, NO, and, to a lesser extent, HCl. The S and species are derived chiefly from the combustion of fossil fuels. Important reactions forming sulfuric acid are... 

When contaminant free hydrogen is used as the fuel in low tempterature combustion reactions (flame temperature less than 2500 Kelvin) all of the toxic products observed in the combustion of fossil fuels are eliminated. The open-air temperature of a hydrogen flame is 2318 Kelvin. Thus, low temperature reactions will occur in properly adjusted kitchen stoves, home and industrial furnaces, and in other low-pressure open-air combustion. 

The combustion of fossil fuels releases energy as well. This energy is in the form of heat, and carbon dioxide and water are formed as the bonds in the fossil fuel rearrange themselves during the combustion reaction. Coal, petroleum, and natural gas are known as fossil fuels and are formed from the decay of living matter. 

Tables 9-8 summarizes the budget of N20 in the troposphere. In addition to emanations from soils and seawater, N20 is released from polluted rivers and estuaries, as a product in the burning of agricultural wastes and biomass, and in the combustion of fossil fuels. Yet another source process of uncertain magnitude is the reaction NH2+N02— N20 + H20 associated with the oxidation of ammonia by OH radicals.

The catalytic oxidation of SO. The process of catalytic oxidation can occur on the one hand on the surface of solid particles and, on the other, as mentioned above, in the liquid phase. One example is a process occurring in hot smoke produced from combustion products emitted from metallurgical works or during the combustion of fossil fuels in power plants. The SO2 conversion to SO3 can be catalysed by metallic components of fly ash suspended in smoke. The reaction occurs at a sufficient rate in the presence of ferric oxide according to the scheme ... 

Sulphur dioxide is produced through the combustion of fossil fuels containing sulfur, such as oil and coal. It is a colorless gas with a pungent odor and can undergo reactions in the atmosphere which contribute to acid rain. It can cause upper respiratory tract irritation and increase the occurrence of respiratory disease. 

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