Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

4.4 Techniques to consider in the determination of BAT4.4.1 Single contact/single absorption processDescriptionChapter 4After purification and drying, the SO 2 is converted into SO 3 using a series of 4 catalyst beds,containing alkali and V 2 O 5 . Afterwards, the SO 3 is absorbed in concentrated sulphuric acid and,if necessary, an oleum absorber is installed upstream. SO 3 reacts with the water contained in theabsorber acid to yield H 2 SO 4 . The absorber acid is kept at the desired concentration ofapproximately 99 % w/w by addition of water or dilute H 2 SO 4 .Heatexchange1CatalystbedsEmissionto air2HeatexchangeTail gastreatment3Heatexchange4HeatexchangeSingleAbsorptionPurifiedand driedSO 2gasDried airH 2SO 4ProductH 2SO 4Figure 4.10: Example for a single contact/single absorption processThis figure is based on [59, Outukumpu, 2005] and [57, Austrian UBA, 2001].Achieved environmental benefitsNote: Conversion rates, tail gas SO 2 concentrations and specific SO 2 load in tail gases arecorrelated, see Figure 4.7, Figure 4.8 and Figure 4.9.Conversion rates >98 % are difficult to achieve in existing plants. However, some plantsachieve conversion rates of 98.5 % [58, TAK-S, 2003].Conversion rates of about 97.5 % are achieved without primary or secondary reductionmeasures [57, Austrian UBA, 2001].New plants achieve conversion rates of 98 – 99 % [59, Outukumpu, 2005].Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 171