Propane stoichiometric calculations

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 ... 

FIGURE 1.6 Calculated stoichiometric flame temperatures of propane and hydrogen in air and oxygen as a function of pressure. 

Based on the design limitations of the pump room bulkheads, it was decided that the bulkheads could easily withstand 15 psi. Calculations show that if the stoichiometric mixture of a hydrocarbon fuel were placed in 10% of the volume and ignited, expansion of the explosion into the remaining 90% of the volume would limit the theoretical maximum pressure to 12 psi, and not affect the bulkheads. With this reasoning 12 pounds of propane were used. 

A direct calculation of the mass of O2 required from the mass of propane is not possible. Instead, first find the moles of propane available, then relate this to moles of O2 required using the stoichiometric factor. Finally, find the mass of O2 required from the moles of O2. 

In a balanced equation, the number of moles of one substance is stoichiometrically equivalent to the number of moles of any other substance. The term stoichiometrically equivalent means that a definite amount of one substance is formed from, produces, or reacts with a definite amount of the other. These quantitative relationships are expressed as stoichiometrically equivalent molar ratios that we use as conversion factors to calculate these amounts. Table 3.3 presents the quantitative information contained in the equation for the combustion of propane, a hydrocarbon fuel used in cooking and water heating ... 

We use units of kJ/mol for the heat of formation of a substance. But in writing the enthalpy change of a chemical reaction, we will use kJ as our preferred unit, not kj/mol. The reaction in this example illustrates why we do this. The value we calculated, AH° = -2219.9 kJ, is for a reaction in which one mole of propane reacts with five moles of oxygen to form three moles of carbon dioxide and four moles of water. So if we were to say -2219.9 kJ/mol, we would need to specify carefully which substance that mol refers to. We choose to write the AH value in kJ, with the understanding that it refers to the reaction as written. This is also dimension-ally consistent with Equation 9.12, provided that we treat the stoichiometric coefficients as carrying units of moles. You may see other texts that refer to values as per mole of reaction. ... 

An attempt was made to calculate the product distributions of propane pyrolysis on the basis of the reaction model considering both inhibition and acceleration effects observed in the pyrolysis of propane-propylene mixtures. The reaction model for propane pyrolysis used in this work is shown in Table 4. The rate constants given in Table 4 were measured in our previous works (3, 4). At the initial stage of propane pyrolysis, the formation of the primary products such as methane, ethylene and propylene is predominant but as the reaction proceeds, the consecutive decomposition of each product is also remarkable. Therefore, a reaction model was postulated which consisted of major stoichiometric reactions for propane (i) - (iv), for propylene (v), (vi) and... 

The dotted lines of Figure 5 show the calculated results us ng only the rate constants given in Table 4 and the dots are the observed concentrations for each component. It can be seen from this figure that the calculated values deviate from the observed values as the amount of propylene produced increases. Consequently, the numerical calculations were tried again using the interactions between propane and propylene in addition to the rate constants in Table 4. In this calculation, it was assumed that the ratios of rate constants for the stoichiometric reactions of propane decomposition (k k ) and of propylene... 

Detailed kinetic calculations demonstrate that if the initial radius of the volume with the detonation products of a stoichiometric propane-air... 

In the reaction of glycerol, /= 3, with equivalent amounts of several diacids, the gel point was observed [14,15] at an extent of reaction of 0.765. The predicted values of are 0.709 and 0.833 calculated from [13] (Flory, statistical) and [12] (Carothers), respectively. Flory [13] studied several systems composed of diethylene glycol (/=2), 1,2,3-propane-tricarboxylic acid (/ = 3), and either succinic or adipic acid (/ = 2) with both stoichiometric and nonstoichiometric amounts of hydroxyl and carboxyl groups, see Table 1. 

To compare the methods in terms of accuracy, number of steps required and time of calculation, oxidation of propane with a stoichiometric amount of air at 2200 K and 40 atm according to the scheme... 

Fig. 11.34 Calculated temperature of stoichiometric gas mixtures compressed behind the reflected wave front [40] (a) hydrogen (b) methane (c) propane dashed line - self-ignition temperature points - experimental data...

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