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

Config

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

•Reagent: For Wet FGD systems, the choice of reagent affects nearly all of the performance and economic parameters of the FGD. Three choices are available:

•Limestone: (This is the default.) Limestone with Forced Oxidation - A limestone slurry is used in an open spray tower with in-situ oxidation to remove SO2 and form a gypsum sludge. The main advantages as compared to conventional systems are easier dewatering, more economical disposal of scrubber products, and decreased scaling on tower walls.

•LS w/ Additives: Limestone with Dibasic Acid Additive - Dibasic acid (DBA) is added to the Limestone to act as a buffer/catalyst in the open spray tower. The main advantages are increased SO2 removal and decreased liquid to gas ratio.

•Lime: Magnesium Enhanced Lime System - A magnesium sulfite and lime slurry (maglime) is used to remove SO2 and form a precipitate high in calcium sulfite. The high alkalinity of the maglime slurry allows very high SO2 removal. However, the reagent cost is also higher and solid waste is not easily disposed.

•Flue Gas Bypass Control: This popup selection menu controls whether or not a portion of the inlet flue gas may bypass the scrubber and recombine with the treated flue gas. Bypass allows the scrubber to operate at full efficiency while allowing some of the flue gas to go untreated. Two choices are available:

•No Bypass: (This is the default.) This option forces the entire flue gas to pass through the scrubber.

•Bypass: This option allows for the possibility of a portion of the flue gas to bypass the scrubber. The amount of bypass is controlled by several additional input parameters described below. These parameters are only visible when this option is selected:

•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.

•Overall SO2 Removal Efficiency: This value is the SO2 removal efficiency required for the entire power plant to meet the SO2 emission constraint set earlier. It is used to determine the actual flue gas bypass above.

•Scrubber SO2 Removal Efficiency: This is the actual removal efficiency of the scrubber alone. It is a function of the SO2 emission constraint and the actual flue gas bypass. This value is also shown on the Performance input screen.

•Minimum Bypass: This specifies the trigger point for allowing flue gas to bypass the scrubber. No bypass is allowed until the allowable amount reaches the minimum level set by this parameter.

•Allowable Bypass: This is the amount of flue gas that is allowed to bypass the scrubber, based on the actual and maximum performance of the SO2 removal. It is provided for reference only. The model determines the bypass that produces the maximum SO2 removal and compares this potential bypass with the minimum bypass value specified above. Bypass is only allowed when the potential bypass value exceeds the minimum bypass value.

•Actual Bypass: This displays the actual bypass being used in the model. It is based on all of the above and is provided for reference purposes only.

•Demister for Outlet Flue Gas: This parameter determines whether a demister is used to remove water from the flue gas exiting the FGD. The default is No Demister.

•Demister Water Removed: (Only shown when a demister is used) This is the amount of water removed by the demister.