IECM 12.0 beta User Manual > Modules Included with the IECM > Pulverized Coal (PC) Plant > SET PARAMETERS > SO2 Control > Wet FGD >

Performance

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Inputs for the performance of the wet FGD system are entered on the Performance parameter screen. The following parameters are available:

•Maximum SO2 Removal Efficiency: This parameter specifies the maximum efficiency possible for the absorber on an annual average basis. The value is used as a limit in calculating the actual SO2 removal efficiency for compliance.

•Scrubber SO2 Removal Efficiency: This is the annual average SO2 removal efficiency achieved in the absorber. The calculated value assumes compliance with the SO2 emission limit specified earlier, if possible. The efficiency is used to determine the liquid to gas ratio and emissions. This input is highlighted in blue.

•Scrubber SO3 Removal Efficiency: The default value is taken from the removal efficiency reported in the literature. This efficiency then determines the mass of SO3 removed from the flue gas in the collector. For more information see also:

•Hardman, R; Stacy, R; Dismukes, E "Estimating Sulfuric Acid Aerosol Emissions from Coal-Fired Power Plants", US DoE-FETC Conference on Formation, Distribution, Impact and Fate of Sulfur Trioxide in Utility Flue Gas Streams 1998 (currently available at https://web.archive.org/web/20040307161115/http://www.netl.doe.gov/publications/proceedings/98/98fg/hardman.pdf)

•Rubin, E. S. "The Importance of Sulfur Trioxide for the Toxic Release Inventory", US DoE-FETC Conference on Formation, Distribution, Impact and Fate of Sulfur Trioxide in Utility Flue Gas Streams 1998 (currently available at https://web.archive.org/web/20030416143712/http://www.netl.doe.gov:80/publications/proceedings/98/98fg/rubin.pdf)

•Particulate Removal Efficiency: This is the percent removal of particulate matter entering the FGD system from the upstream particulate collector. Particulate collectors are designed to comply with the specified particulate emission limit. This is additional particulate removal.

•Absorber Capacity: This is the percent of the flue gas treated by each operating absorber. This value is used to determine the number of operating absorbers and the capital costs.

•Number of Operating Absorbers: This is the number of operating scrubber towers. The number is determined by the absorber capacity and is used to calculate the capital costs. The value must be an integer.

•Number of Spare Absorbers: This is the total number of spare absorber vessels. It is used primarily to calculate capital costs. The value must be an integer.

•Liquid to Gas Ratio: The design of spray towers for high efficiency is achieved by using high liquid-to-gas (L/G) ratios. The calculated value is a function of the reagent type, the removal efficiency, and stoichiometry. It determines the power requirement and capital cost.

•Reagent Stoichiometry: This is the moles of calcium per mole of sulfur removed from the absorber. The stoichiometry is calculated as a function of the reagent type. It is used to determine the liquid to gas ratio, reagent usage, reagent waste, and capital cost.

•Reagent Purity: This is the percent of the reagent that is lime (CaO) or limestone (CaCO3). The calculated value is a function of the reagent type. This parameter determines the waste solids produced and the reagent needed to remove the necessary SO2.

•Reagent Moisture Content: This is the moisture content of the reagent. The remaining reagent impurities are assumed to be inert substances such as silicon dioxide (sand). This parameter is used to determine the waste solids produced.

•Total Pressure Drop across FGD: This is the total pressure drop across the FGD vessel prior to the reheater. This is used in the calculations of the power requirements (or energy penalty) and thermodynamic properties of the flue gas.

•Temperature Rise Across ID Fan: An induced draft (ID) fan is assumed to be located upstream of the FGD system. The fan raises the temperature of the flue gas due to dissipation of electro-mechanical.

•Gas Temperature Exiting Scrubber: A thermodynamic equation is used to calculate this equilibrium flue gas temperature exiting the scrubber. The gas is assumed to be saturated with water at the exiting temperature and pressure. The value determines the water evaporated in the scrubber.

•Gas Temperature Exiting Reheater: This is the desired temperature of flue gas after the reheater. It is assumed to be equal to the stack gas exit temperature. If scrubber bypass is employed, reheat requirements are reduced or eliminated. It determines the reheat energy required.

•Entrained Water Past Demister: This is a liquid water entrained in the flue gas leaving the demister expressed as a percentage of the total water evaporated in the absorber.

•Wet FGD Power Requirement: This is the equivalent electrical output of thermal (steam) energy used for reheat, plus the actual electrical output power required for pumps and booster fans.