Carbon monoxide combustion constants

Values of yields for various fuels are listed in Table 2.3. We see that even burning a pure gaseous fuel as butane in air, the combustion is not complete with some carbon monoxide, soot and other hydrocarbons found in the products of combustion. Due to the incompleteness of combustion the actual heat of combustion (42.6 kJ/g) is less than the ideal value (45.4 kJ/g) for complete combustion to carbon dioxide and water. Note that although the heats of combustion can range from about 10 to 50 kJ/g, the values expressed in terms of oxygen consumed in the reaction (Aho2) are fairly constant at 13.0 0.3 kJ/g O2. For charring materials such as wood, the difference between the actual and ideal heats of combustion are due to distinctions in the combustion of the volatiles and subsequent oxidation of the char, as well as due to incomplete combustion. For example,... 

In combustion systems it is generally desirable to minimize the concentration of intermediates, since it is important to obtain complete oxidation of the fuel. Figure 13.5 shows modeling predictions for oxidation of methane in a batch reactor maintained at constant temperature and pressure. After an induction time the rate of CH4 consumption increases as a radical pool develops. The formaldehyde intermediate builds up at reaction times below 100 ms, but then reaches a pseudo-steady state, where CH2O formed is rapidly oxidized further to CO. Carbon monoxide oxidation is slow as long as CH4 is still present in the reaction system once CH4 is depleted, CO (and the remaining CH2O) is rapidly oxidized to CO2. 

In this scheme, Reaction 1 represents a direct (pre-ignition) combustion reaction which may or may not be accompanied by formation of carbon monoxide Reaction 2 describes the oxidation reaction (and its sequences) examined in the present study. B and C in Reaction 2 denote degradation products of humic acids (e.g. hymatomelanic, fulvic, and/or so-called water soluble coal acids), and ki,, etc. represent the corresponding rate constants. 

What problems face the theory of combustion The theory of combustion must be transformed into a chapter of physical chemistry. Basic questions must be answered will a compound of a given composition be combustible, what will be the rate of combustion of an explosive mixture, what peculiarities and shapes of flames should we expect We shall not be satisfied with an answer based on analogy with other known cases of combustion. The phenomena must be reduced to their original causes. Such original causes for combustion are chemical reaction, heat transfer, transport of matter by diffusion, and gas motion. A direct calculation of flame velocity using data on elementary chemical reaction events and thermal constants was first carried out for the reaction of hydrogen with bromine in 1942. The problem of the possibility of combustion (the concentration limit) was reduced for the first time to thermal calculations for mixtures of carbon monoxide with air. Peculiar forms of propagation near boundaries which arise when normal combustion is precluded or unstable were explained in terms of the physical characteristics of mixtures. 

Carbon monoxide appears at the entrance of the combustion chamber close to the wall but quickly disappears. Carbon monoxide reappears again with a pattern very similar to hydrogen in the vicinity of the reaction zone (Fig. 9). Beyond this zone the carbon monoxide concentration is essentially constant across the reactor, with increasing concentration with tunnel length. 

The heat of combustion at constant pressurci Wp has been found for carbon monoxide (CO = 28) to be 68000, According to the equation... 

The comparison of the experimental data for the nanocomposites on the basis of the rtylon-6, polypropylene and polystyrene gathered in Table 7 show that the heat of combustion, the smoke release and the amount of the carbon monoxide are almost constant at varying organoclay content. So we conclude that the source for the increased refractoriness of these materials is the stability of the solid phase and not the influence of the vapor phase. The data for the polystyrene with the 30% of the dek-abrominediphenyloxide and Sb203 are given in Table 6 as the proof of the influence of the vapor phase of bromine. The incomplete combustion of the polymeric material in the latter case results in low value of the heat of the combustion and high quantity of the carbon monoxide released [79]. 

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