Carbon monoxide, atmospheric combustion

Nitrogen Oxides. From the combustion of fuels containing only C, H, and O, the usual ak pollutants or emissions of interest are carbon monoxide, unbumed hydrocarbons, and oxides of nitrogen (NO ). The interaction of the last two in the atmosphere produces photochemical smog. NO, the sum of NO and NO2, is formed almost entkely as NO in the products of flames typically 5 or 10% of it is subsequently converted to NO2 at low temperatures. Occasionally, conditions in a combustion system may lead to a much larger fraction of NO2 and the undeskable visibiUty thereof, ie, a very large exhaust plume. 

A substantial portion of fhe gas and vapors emitted to the atmosphere in appreciable quantity from anthropogenic sources tends to be relatively simple in chemical structure carbon dioxide, carbon monoxide, sulfur dioxide, and nitric oxide from combustion processes hydrogen sulfide, ammonia, hydrogen chloride, and hydrogen fluoride from industrial processes. The solvents and gasoline fractions that evaporate are alkanes, alkenes, and aromatics with relatively simple structures. In addition, more complex... 

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... 

Almost all the major car, bus, and truck manufacturers have developed compressed natural gas engines and vehicles. These manufacturers have been able to offer better performance (due to higher octane) and far lower emissions of nitrogen oxides, carbon monoxide, particulate matter, and carbon dioxide to the atmosphere. In 1998, Honda introduced the cleanest internal combustion engine vehicle ever commercially produced the natural gas Civic GX with emissions at one-tenth the state of California s Ultra Low Emission Vehicle standard. Primarily due to the high octane of natural gas, Honda achieved these results without sacrificing performance. 

The process will adversely affect air quality by releasing nitrogen oxides, sulfur oxides, carbon monoxides and other particulates into the atmosphere. Better control of the conversion conditions and better control of emissions can make the process cleaner, yet technology cannot do anything to curb carbon emissions. Since much of the carbon in coal is converted to carbon dioxide in the synthesis process, and is not part of the synthetic fuel itself, the amount of carbon dioxide that will be released to the environment during combustion is 50 to 100 percent more than coal, and around three times more than natural gas. 

The recycling of PVC by hydrothermal techniques is described, in which PVC is thermally converted in a steam atmosphere into hydrogen chloride, hydrogen, carbon dioxide, carbon monoxide and some gaseous and liquid hydrocarbons. Whilst gasification with only steam is an endothermic reaction, partial combustion of PVC by the addition of small amounts of air, enables autothermic operation of the process to take place. This work deals... 

Simultaneous analysis of C, H, and N in liquid or solid organic materials may be carried out after combustion in an oxygen atmosphere at temperatures up to 1000 °C. The gaseous combustion products (CO2, H2O, N2) are flushed with a carrier gas (helium) through a reductant, and quantification is obtained by GC. For analysis of O, the combustion is performed in helium over platinised carbon. Carbon monoxide formed is converted to CO2 by passage over CuO, and measured in the same manner as for analysis of C. A 2-3 mg sample is required. 

Monitor carbon monoxide on a continuous basis at a point downstream of the combustion zone and prior to release into the atmosphere. 

Methane, also referred to as marsh gas, is a gas composed of carbon and hydrogen with a chemical formula of CH4. It is the first member of the paraffin or alkane series of hydrocarbons. It is lighter than air, colorless, odorless, tasteless and is flammable. It occurs in natural gas and as a by-product of petroleum refining. In atmospheric burning no smoke production normally occurs. In air methane bums with a pale, faintly luminous flame. With excess air carbon dioxide and water vapor is formed during combustion, with an air deficiency carbon monoxide and water is formed. It forms an explosive mixture with air over a moderate range. Its primary uses are as a fuel and raw feedstock for petrochemical products. 

A gaseous paraffinic hydrocarbon, CHj.CHj that is colorless and odorless and normally found in natural gas, usually in small proportions. It is slightly heavier than air and practically insoluble in water. When ignited in atmospheric burning it produces a pale faintly luminous flame with little or no smoke production. With excess air during combustion it produces carbon dioxide and water, with limited air supplies the combustion process will produce carbon monoxide and water. It forms an explosive mixture with air over a moderate range. 

The combination of oxygen with a material in an oxygen-deficient atmosphere that generally results in carbon monoxide being one of the combustion products. 

Chemical/Physical. Diuron decomposes at 180 to 190 °C releasing dimethylamine and 3,4-dichlorophenyl isocyanate. Dimethylamine and 3,4-dichloroaniline are produced when hydrolyzed or when acids or bases are added at elevated temperatures (Sittig, 1985). The hydrolysis half-life of diuron in a 0.5 N NaOH solution at 20 °C is 150 d (El-Dib and Aly, 1976). When diuron was pyrolyzed in a helium atmosphere between 400 and 1,000 °C, the following products were identified dimethylamine, chlorobenzene, 1,2-dichlorobenzene, benzonitrile, a trichlorobenzene, aniline, 4-chloroaniline, 3,4-dichlorophenyl isocyanate, bis(l,3-(3,4-dichlorophenyl)urea), 3,4-dichloroaniline, and monuron [3-(4-chlorophenyl)-l,l-dimethylurea] (Gomez et al., 1982). Products reported from the combustion of diuron at 900 °C include carbon monoxide, carbon dioxide, chlorine, nitrogen oxides, and HCl (Kennedy et al., 1972a). 

There are two interesting molecules that are derived from carbon and oxygen alone. Earlier, we encountered carbon dioxide, CO2, as a constituent of our atmosphere, a product of the combustion of fossil fuels, and a major contributor to global warming. An even simpler molecule is carbon monoxide, CO, a toxic gas and a minor product of incomplete combustion of fossil fuels. 

Carbon monoxide, which is predominantly produced during combustion processes, may exhibit an 0 excess of up to 7.5%c in summer at high northern latitudes (Rockmann et al. 1998). The major source of this fractionation is its atmospheric removal reaction CO + OH = CO2 + H2, in which the remaining CO gains excess 0. 

The control of carbon monoxide emissions is based on the principle that less of the gas is produced when the efficiency of combustion is improved. One device to achieve this objective is the catalytic converter, now required on all motor vehicles sold in the United States. A catalytic converter provides a second stage of combustion in motor vehicles, allowing carbon monoxide and other unburned components of a fuel to be oxidized before release into the atmosphere. (The operation of a catalytic converter is described later in this chapter.)... 

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