Dry flue gas

Basis 100 mol, dry flue gas as the analysis of the flue gas is known, the mols of each element in the flue gas (flow out) can be easily calculated and related to the flow into the... 

FW-BF [Foster Wheeler-Bergbau-Forschung] A dry flue-gas desulfurization process that combines the sulfur removal system of Bergbau-Forschung, which uses a carbon adsorbent, with the Foster-Wheeler process for oxidizing adsorbed sulfur to sulfuric acid. 

LIFAC [Limestone in-fumace and Added Calcium] A dry flue-gas desulfurization process in which limestone is injected into the lumace and calcium hydroxide is injected after it. Developed by Tampella in 1984 and used in a power station in Finland. A demonstration plant was built for Saskatchewan Power, Canada, in 1990. 

Boiler Thermal Efficiency Traditionally, boiler thermal efficiency is calculated pour/pm, where in is the LHV (lower heating value) of the fuel. A rule of thumb for economizers is that boiler efficiency increases by 1 percent for every 22°C (40°F) drop in temperature of the dry flue gas. These two statements do not reveal the considerable quantity of additional heat, available to be recovered through condensation of the water vapor in the flue gas, which is lost to atmosphere with hot flue gas. Based on fuel HHV (higher heating value), the total latent heat loss can be substantial an additional 9.6 percent (natural gas), 8.0 percent (propane), 6.5 percent (heating ou). 

The current method measures water vapour indirectly based on oxygen measurements in wet and dry flue gas. There are two disadvantages with this solution (a) the measurement uncertainty is relatively high it is very sensitive to system errors, for example bad calibration (b) if hydrocarbons are present in the flue gas they will interfere with the water vapour analysis. 

Analyses of Hue gases are always repotted on a volume basis, dry, when an Orsai or other type of gas analysis is used. Flue gases are cooled to room temperature and bubbled through water in most gas analyses, so that the gas becomes saturated with water vapor. This would occur even if no water vapor were formed during combustion. Proportionate parts of the water vapor content of the gas will be absorbed with the different constituents of the gas so that the resulting analysis may be safely assumed to be that of dry gas. These percentages may also be expressed as 10.4 moles COi, 2.8 moles Oi. and 86.8 moles N2 each per 100 moles of dry flue gas. 

For each mole of C burned, one mole of CO2 is formed. From the fuel analysis used there are 110.6 moles C per 100 moles of fuel, and there are also 110.6 moles of COi formed from the 110.6 moles C in the fuel. From the flue gas analysis, there are 100/10.4 = 9.62 moles of dry flue gas per mole of C02. The 100 moles of fuel will then yield 110.6 x 9.62 = 1,064 moles of dry flue gas. By the application of the mole method, an important value has been quickly determined through knowing only the flue gas analysis and the fuel analysis. 

From the flue gas analysis, the molecular weight of the dry flue gas can be easily determined, as follows ... 

Thus. 1,805 pounds of gas fuel yield 31,700 pounds of dry flue gas, and each pound of gas fuel yields 31.700/1, 805 = 17.6 pounds dry flue gas. 

Select a basis and a tie component, and write out the relevant equations involved. Select 100 kg mol dry flue gas as the basis. Since nitrogen passes through the system unreacted, select it as the tie component. That is, the other components of the system can be referred to nitrogen as a basis, thus simplifying the calculations. 

Since dry flue gas is the basis, containing C02 and CO, the relevant reactions and the quantities per 100 mol flue gas are... 

Graf. R. "First operating experience with a dry flue gas desulphurization (FGD) process using a circulating fluid bed (FGD-CFB), in "Circ. Fluid. Bed Technol. (Basu, P., and Prabir, X., eds.), pp. 317-27. Pergamon, Toronto (1986). 

Graf, Rolf. Riley, John D., and Erdoel Kohle. "Dry/semi-dry flue gas desulphurization Lurgi circulating fluid bed absorption process, Erdgas, Petrochem., Vol. 40, pp. 263-8 (1987). 

The data for pine wood, Kentucky bluegrass, biomass fuel was assumed to contain 15.0 wt f dry flue gas, which were calculated from the combustion is complete, the ash and nitrogen... 

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