Stoichiometry problems definition

Problem definition. Firstly the key components are identified. These are products, sub-products and intermediates, as well as impurities with significant effect on product quality and operation. Then the impurities are traced by means of tables containing sources, sinks, exit streams, transit units and process streams. Formation and depletion of impurities must be supported by a consistent stoichiometry. Then an operating window is defined in terms of production rate, operation parameters and technological constraints. In principle, this step may identify a number of flowsheet alternatives, but supplementary alternatives may arise during the application of the procedure. 

Problem definition. The key impurities are traced by means of tables containing sources, sinks, exit streams, and transit units. Their formation and depletion must be supported by consistent stoichiometry. This step may lead to flowsheet alternatives by changing the... 

The concept of chemical components. Each species can be expressed as the product of a set of chemical components that define the equilibrium problem and a formation constant. Morel (1983) has expressed the definition of the chemical components as a set of chemical entities that permits a complete description of the stoichiometry of the system . For the example of the hydroxy-aluminium species given above Al3+ and H+ are the chemical components. As will be seen in the section on surface complexes the components are not necessarily elements or species. The components concept is important for understanding how to set up chemical equilibrium problems with various computer models. 

Note that this definition differs slightly from the one commonly used in industry in which the stoichiometry is usually defined as the total oxidizer flow divided by the fuel flow. The problem with the definition commonly used in industry is that the stoichiometry must be recalculated whenever the oxidizer composition changes and that stoichiometric conditions change for each oxidizer composition. This is not a concern if air is always used as the oxidizer, which is the case for the vast majority of combustion processes. The benefit of the definition used here is that stoichiometry is independent of the oxidizer composition, so stoichiometric conditions are the same for any oxidizer composition. In Equation 1.2, S = x/1 = x. Theoretically, for the complete combustion of CH4, S = 2.0. Actual flames generally require some excess 02 for complete combustion of the fuel. This is due to incomplete mixing between the fuel and oxidant. For the fuel rich combustion of CH4, S < 2.0. For the fuel lean combustion of CH4, S > 2.0. 

It is important to remember that the order of the reaction is determined experimentally. Although this problem focuses on the mathematical detail of the definition of reaction order, we must keep in mind that reaction order and stoichiometry are not directly related. 

Both concepts about definite composition or stoichiometry by Dalton are the criterion and standard for confirming a compound, and many properties of compounds are explained by the infrangible theory of constant composition. Problems concerning the molecular crystals in organic chemistry were explained well by this theory according to the principle of constant valence, while it was found out to be not always proper to the case of atomic or ionic crystal compounds. In fact, Berthollet pointed out early based on the experimental results that crystal compounds would not always follow the law of constant composition. The compositions of an identical compound could be changed in a certain ranges. 

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