Abstract: A wet, calcium-based flue gas desulfurization process conducted under inhibited oxidation conditions and in the presence of at least one organic acid which both enhances the efficiency of sulfur dioxide removal and modifies the crystal habit of calcium sulfite crystals to produce large, thick, regular, easily dewatered calcium sulfite hemihydrate byproduct solids is provided. The addition of an organic acid, preferably a carboxylic acid, to the flue gas desulfurization process produces calcium sulfite crystals that closely resemble calcium sulfate or gypsum crystals in settling and dewatering properties.

Abstract: An on-line control and monitoring system for automatically and continuously analyzing key process indicators in a wet lime/limestone flue gas desulfurization process is provided. The on-line control and monitoring system obtains a slurry and/or a slurry flitrate which is directed at selected fluid flow rates to one or more analytical devices each selected to analyze a flue gas desulfurization process indicator. Data is provided to a data acquisition system which processes the analysis results from the analytical devices and provides flue gas desulfurization process control information. This on-line monitoring and control system can be used to monitor and control the addition rate of performance enhancement additives such as organic acids, thiosulfate, oxidation air and the like.

Abstract: A continuous filtration system for supplying an uninterrupted supply of filtrate from a solids-containing industrial process suitable for use by on-line automatic analyzers is provided. The continuous filtration system, which is particularly useful for filtering flue gas desulfurization process slurry to produce a solids-free filtrate for autoanalysis, includes a pair of filters connected in series which concurrently receive a tangential flow of slurry into the filter head that is discharged perpendicularly through a filtrate head. An automatic flushing system is provided to keep the filter membranes free of solid particles. An optional autoanalyzer for unfiltered slurry may also be included in the system.

Abstract: A process for producing large, regularly-shaped crystalline gypsum solids in a wet calcium-based flue gas desulfurization system is provided. A chemical crystal modifier, preferably an organophosphonate, is added to the gypsum-containing solids slurry produced by the FGD process under forced oxidation conditions at an addition level which promotes the formation of large, regular gypsum crystals that are easily dewatered. The dewatered gypsum is useful in producing gypsum-based building products and the like.

Abstract: A process for producing large, regularly-shaped crystalline calcium sulfite solids in a wet calcium-based flue gas desulfurization system is provided. A chemical crystal modifier, preferably an organophosphonate, is added to the calcium sulfite-containing solids slurry produced by the FGD process under inhibited oxidation conditions at an addition level which promotes the formation of large, regular calcium sulfite crystals that are easily dewatered.