Excess air or oxygen

The heat of combustion is a product of the amount of fuel consumed and the net heating value of the fuel. The heater s efficiency is a function of the flue-gas stack temperature, the excess air or oxygen, and the ambient-heat losses from the firebox and the convective-section structures. 

Carbon dioxide, 0=C=6 , mp —57°C (5.2 atm), bp —79 °C (sublimes), is obtained from the combustion of carbon and hydrocarbons in excess air or oxygen or by the pyrolysis ( calcination ) of CaCOs (limestone). The photosynthesis in plants reduces CO2 to organic matter, but the similar reduction of CO2 in a nonliving system ( in vitro ) appears to be very difficult. However, CO2 can be reduced electrochemically to methanol, formate, oxalate, methane, and/or CO depending upon the conditions. Numerous transition metal complexes of CO2 are known,which exhibit the modes of metal-C02 bonding depicted in Figure 2. 

The calculated amount of excess air does not depend on how much material is actually burned but what can be burned. Even if only partial combustion takes places, as, for example, C burning to both CO and CO2, the excess air (or oxygen) is computed as if the process of combustion produced only CO2. The... 

This interesting viewpoint, which affords relief from the theories of surface action, was taken by Lucke in his early development of what was virtually the first surface combustion process.58 In contrast to the other workers in the field, Lucke did not approach the problem from the viewpoint of catalytic action, but from the viewpoint of holding the flame o f an explosive mixture stationary.20 He recognized that it is desirable to obtain complete combustion without excess air or oxygen, and pointed to the utility of being able to bum an explosive mixture continuously and non-... 

Usually, a fuel is properly burned with excess air or oxygen to ensure complete combustion and prevent the formation of soot. The excess of air is usually characterized by the air excess ratio defined as ... 

The percentage composition of a hydrocarbon is usually found by combusting a known mass of the pure compound in excess air or oxygen, then finding the masses of both the carbon dioxide (formed from the carbon in the compound) and the water (formed from the hydrogen). 

The function of the oxygen sensor and the closed loop fuel metering system is to maintain the air and fuel mixture at the stoichiometric condition as it passes into the engine for combustion ie, there should be no excess air or excess fuel. The main purpose is to permit the TWC catalyst to operate effectively to control HC, CO, and NO emissions. The oxygen sensor is located in the exhaust system ahead of the catalyst so that it is exposed to the exhaust of aU cylinders (see Fig. 4). The sensor analyzes the combustion event after it happens. Therefore, the system is sometimes caUed a closed loop feedback system. There is an inherent time delay in such a system and thus the system is constandy correcting the air/fuel mixture cycles around the stoichiometric control point rather than maintaining a desired air/fuel mixture. 

Alkanes burn in a plentiful supply (excess) of air or oxygen to form carbon dioxide and water. Because such combustion reactions are exothermic, alkanes are very useful as fuels. 

The catalytic oxidation of liquid hydrocarbons with air or oxygen. Since oxygen is not very soluble in the liquid, while the hydrocarbon could well be present in high concentration we could end up in extreme 1 (excess of B). The removal of dissolved organics from industrial waste water by catalytic oxidation as an alternative to biooxidation. Here oxygen is not very soluble in water, but the organic waste is also present in low concentration. It is therefore not clear in what regime the kinetics lie. The catalytic oxidation of phenol is an example of such an operation. 

The adiabatic flame temperature is the maximum theoretical temperature that can be reached by the products of combustion of a specific fuel and air (or oxygen) combination assuming no loss of heat to the surroundings until combustion is complete. This theoretical temperature also assumes no dissociation, a phenomenon discussed later under this heading. The heal of combustion of Ihe fuel is the major factor in the flame temperature, but increasing the temperature of the air or of the fuel will also have the effect of raising the flame temperature. As would be expected, this adiabatic temperature is a maximum with zero excess air (only enough air chemically required lo combine with the fuel), since any excess is not... 

Carbon dioxide is produced whenever a carbon containing substance burns in excess of air or oxygen. 

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