Combustion of propane

Stoichiometric Concentration (Used by permission of Frank T. Bodurtha, Inc., New London, New Hampshire). In a combustion reaction in air, the stoichiometric concentration, Cjt, of any reac tant is the concentration theoretically required for complete conversion by reacting completely with oxygen. For example, for the combustion of propane in air ... 

The change in moles upon the combustion of propane and many other hydrocarbons is either zero or small. Usually, pressure rise in the combustion of a vapor or gas is due mainly to change in temperature, not change in moles. 

Deflagration Pressure The increase in pressure in a vessel from a deflagration results from an increase in temperature the ac tual maximum flame temperature for propane, for example, is I925°C (3497°F). No significant increase in moles of gas to cause pressure buildup results from combustion of propane in air. 

Stoichiometry in Reactive Systems. The use of molar units is preferred in chemical process calculations since the stoichiometry of a chemical reaction is always interpreted in terms of the number of molecules or number of moles. A stoichiometric equation is a balanced representation that indicates the relative proportions in which the reactants and products partake in a given reaction. For example, the following stoichiometric equation represents the combustion of propane in oxygen ... 

Consider foe combustion of propane, C3H8j foe fuel that is commonly used in portable gas barbeque grills. The products of combustion are carbon dioxide and liquid water. 

Use the information in Table 6.5 and the enthalpy of combustion of propane gas to calculate the enthalpy of formation of propane, a gas commonly used for camping stoves and outdoor barbecues. 

The combustion of propane to form gaseous products is an example of a reaction that is spontaneous at all... 

Combustion of propane C3H8 + 502 —> 3C02 + 4H20 Combustion of ethanol C2H5OH + 302 —> 2C02 + 3H20... 

For most hydrocarbon combustion explosions in air the change in the number of moles is small. For example, consider the combustion of propane in air. The stoichiometric equation is... 

Speciation in a gas mixture. Let us work out a case provided by Van Zeggeren and Storey (1970), involving combustion of propane in air in the proportions of one mole of propane (C3H8) and five moles of air (Oz + 4N2) at 40 atm and 2200 K, which provides a nice illustration of how to calculate the production of greenhouse gases by automobiles. 

Example 1 Combustion of propane (C3H8, 50 kg/hr) occurs at ambient conditions (77 F, 1 atm). 

Chemical/Physical. Incomplete combustion of propane in the presence of excess hydrogen chloride resulted in a high number of different chlorinated compounds including, but not limited to alkanes, alkenes, monoaromatics, alicyclic hydrocarbons, and polynuclear aromatic hydrocarbons. Without hydrogen chloride, 13 nonchlorinated polynuclear aromatic hydrocarbons were formed (Eklund et al, 1987). 

Mention should be made of studies of slow, controlled combustion of alkanes, where formation of oxetanes can be detected. For example, oxetane is observed during combustion of propane, while 2-f-butyl-3-methyloxetane and 2-isopropyl-3,3-dimethyloxetane are observed from combustion of isooctane. While the yields are extremely low, the presence of these compounds, along with the other products found, have provided evidence for the mechanism of combustion. The oxetanes are believed to result from rearrangement of peroxy radicals in the radical chain process (equation 114) (70MI51300,73MI51301). 

A chemical equation for the combustion of propane, C3H8, is shown below. Through this reaction is the carbon oxidized or reduced ... 

Write a balanced chemical equation to represent the combustion of propane. 

The enthalpy changes at 298K and latm for the hydrogenation and for the combustion of propane are given below ... 

Carbon Monoxide Oxidation. Analysis of the carbon monoxide oxidation in the boundary layer of a char particle shows the possibility for the existence of multiple steady states (54-58). The importance of these at AFBC conditions is uncertain. From the theory one can also calculate that CO will bum near the surface of a particle for large particles but will react outside the boundary layer for small particles, in qualitative agreement with experimental observations. Quantitative agreement with theory would not be expected, since the theoretical calculations, are based on the use of global kinetics for CO oxidation. Hydroxyl radicals are the principal oxidant for carbon monoxide and it can be shown (73) that their concentration is lowered by radical recombination on surfaces within a fluidized bed. It is therefore expected that the CO oxidation rates in the dense phase of fluidized beds will be suppressed to levels considerably below those in the bubble phase. This expectation is supported by studies of combustion of propane in fluidized beds, where it was observed that ignition and combustion took place primarily in the bubble phase (74). More attention needs to be given to the effect of bed solids on gas phase reactions occuring in fluidized reactors. 

First calculate the standard heat of combustion of propane C3H8 + 502 = 3C02(g) + 4H20 (g)... 

The total energy change that occurs during the combustion of propane is then ... 

Hydrocarbon compounds will burn in the presence of air to produce oxides. This is a chemical property of all hydrocarbons. Complete combustion occurs if enough oxygen is present. A hydrocarbon that undergoes complete combustion produces carbon dioxide and water vapour. The following equation shows the complete combustion of propane. (See also Figure 14.3.)... 

If you burn a fuel, such as propane, in a barbecue, you want complete combustion to occur. Complete combustion ensures that you are getting maximum efficiency from the barbecue. More importantly, toxic gases can result from incomplete combustion combustion that occurs when not enough oxygen is present. During incomplete combustion, other products (besides carbon dioxide and water) can form. The equation below shows the incomplete combustion of propane. Note that unburned carbon, C(s), and carbon monoxide, C0(g), are produced as well as carbon dioxide and water. 

The formation of propane from its elements is an exothermic reaction. The combustion of propane is also exothermic. 

Which equation shows the complete combustion of propane ... 

Explosion pressure is primarily the result of temperature reached during combustion, not a change in moles. With complete combustion of propane in air there is a negligible change in moles of gas ... 

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