PAPERS SELECTED FOR THE SYMPOSIUM

• Performance of FGD Plants

  Franz Hafner - Austrian Energy & Environment AG &Co KG, Raaba/Graz; Austria

  Abstract Text

  To reduce the SO2 content in the flue gas of power plants and industrial boilers mainly three processes have been applied: dry, semi-dry and wet desulphurization. FGD technology in Europe has now gained about 25 years of experience; this allows... show full text »
  Abstract Text

  To reduce the SO2 content in the flue gas of power plants and industrial boilers mainly three processes have been applied: dry, semi-dry and wet desulphurization. FGD technology in Europe has now gained about 25 years of experience; this allows us some statements: Wet and dry FGD processes are the best choice under economic and technical considerations. Weather to use the wet or dry FGD process depends mainly on the amount of flue gas flow, SO2 content, type of plant (power station, industrial plant, waste/biomass incineration) and on the calculated lifetime of the plant. This will be discussed in detail. For big power stations the best solution will be the wet limestone process. The technical performance of wet and dry FGD has been improved with AE&E setting milestones in the technical progress. (Examples will be shown). Thus, it has been and may still be profitable to upgrade some older FGD plants. Some words on the improvements of wet FGD technology: Up until 1995 the wet spray scrubber was considered to be a device mainly dominated by the exchange of chemical compounds. As limiting factors for the performance of gypsum deposition was considered: • The reactivity of the absorption agent • The reactivity of the circulating water • The area of mass transfer produced by the spray nozzles Flow effects were considered to be of less significance. In 1995 the profile of SO2 concentration was measured beneath the mist eliminators in our plant in Sostanj/Slowenia. The results have shown a precarious asymmetry, which could only be the effect of flow dynamics. Based on this experience AE&E together with the University of Leoben developed a mathematical model allowing for the calculation of the gas flow, including the chemical reactions in the absorber. AE&E has also constructed absorbers using new materials: Additional to the classic steel absorber with rubber lining, stainless steel was used. Recently concrete absorbers with PP lining were built. In order to expell flue gases with lower temperatures AE&E has realized two new methods: A wet stack on the top of an absorber Allowing the flue gases to pass through a cooling tower instead of a stack. Also dry technology has been improved. The state of the art of old technology was to inject the absorbents into the flue gas and separate them later with fabric filters. This resulted in high operation costs, because the efficiency in the use of absorbents was very low. AE&E introduced a turbo reactor which allows a very economic use of absorbents and a high degree of desulphurization (Turbosorp® process). Additionally, it is possible with different composition of absorbents to also extract other pollutants from the flue gas. In order to demonstrate our achievements on the performance of FGD plants, some of our latest projects will be discussed. « hide
  Symposium Session: Environmental aspects of power generation | Ekološki i klimatski aspekti rada elektrana