A coal from Colorado which has an ultimate analysis (by...

A coal from Colorado which has an ultimate analysis (by mass) of 79.61 percent $\mathrm{C}, 4.66$ percent $\mathrm{H}_{2}, 4.76$ percent $\mathrm{O}_{2}$, 1.83 percent $\mathrm{N}_{2}, 0.52$ percent $\mathrm{S},$ and 8.62 percent ash (noncombustibles) is burned in an industrial boiler with 10 percent excess air. The temperature and pressure in the smokestack are $50^{\circ} \mathrm{C}$ and 1 atm, respectively. Calculate the fraction of the water in the combustion products that is liquid and the fraction that is vapor.

Key Concepts

Phase Equilibrium of Water

This concept pertains to the conditions at which water exists as either vapor or liquid. The equilibrium between the vapor and liquid phases of water is determined by the ambient temperature and pressure, which dictate the saturation conditions. In combustion systems, understanding phase equilibrium is crucial for predicting how much of the produced water will condense versus remain as vapor in the exhaust stream.

Excess Air

Excess air refers to the additional air provided beyond the amount needed for theoretically complete combustion. Including excess air in combustion calculations improves the combustion efficiency by ensuring complete oxidation of the fuel and affects the final composition of the flue gases by diluting the combustion products and nitrogen content.

Flue Gas Composition in Combustion

Flue gas composition analysis involves determining the concentrations of various products resulting from combustion, such as CO2, H2O, O2, and inert gases like N2. This analysis is fundamental not only for assessing combustion efficiency but also for evaluating environmental impact and for designing systems to handle, treat, or recover components like water from the exhaust.

Ultimate Analysis

This involves determining the elemental composition of a fuel, such as percentages of carbon, hydrogen, oxygen, nitrogen, sulfur, and inert material. In the context of fuel combustion, the ultimate analysis is essential to establish the stoichiometric ratios required for complete combustion, as well as to accurately calculate the quantities of combustion products such as CO2, H2O, and other species.

Combustion Stoichiometry

Combustion stoichiometry is the process of balancing the chemical reaction of fuel combustion, ensuring that the reactants and products obey the conservation of mass and energy laws. It helps in determining how much of each reactant (fuel and oxygen from air) is required and what products (such as carbon dioxide, water, and other gases) are produced in the reaction.

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