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Analysis and quantification of foaming phenomena in wet FGD plants. Siqiang QIN Ph.D. student. Supervisors: Søren Kiil Brian Brun Hansen. Content. Introduction Foaming and antifoam in wet FGD Future work. Introduction.
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Analysis and quantification of foaming phenomena in wet FGD plants Siqiang QIN Ph.D. student Supervisors: SørenKiil Brian Brun Hansen
Content • Introduction • Foaming and antifoam in wet FGD • Future work
Introduction The wet scrubber FGD process is the most widespread desulphurisation technology. Source: WPCA/Duke:2008
Fundamental chemistry in wet FGD • Major reactions (Kiil, 1998) • The absorption of SO2 • The oxidation of HSO3- to SO42- • The dissolution of the reactant (limestone) • The crystallisation of gypsum • This study will focus on the foaming issue in wet FGD • Long term foaming ability • Long term effects on antifoam ability • The interaction of foaming and antifoam on desulphurisation efficiency
What is foam? Foam: is a gas dispersed in a liquid with some impurity. Foam in FGD Reactor Tank: Bad Foam Good Foam Source: Mega Symposium 2008
Foam in wet FGD What kind of issue can foam induce? • Wrong Liquid levels readings • cavitation of recycling pumps • short gypsum residence/growth time • Foam in reactor tank can enter ductwork and flow into equipment • Housekeeping problems • Corrosion • Wrong density measurement • no gypsum withdrawel & excessive solid concentration Source: Encyclopædia Britannica, Inc.
Strategies to solve foam problems in wet FGD • Design View: • Inlet duct floor temperature indicators • Reaction tank “viewing stations” • Foam Detection Nozzles • Chemical View: commercial deformers: mixtures of hydrophobic liquids and solids Source: Siemens AG 2007 5
Foaming agents and antiformers Foaming agents: SDS; adipic acid; two albumins Commerical antifoam: GE Foamtrol AF 2290; GE Foamtrol AF 1440; NALCO antifoam 7468; NALCO antifoam 7468; Dow Corning 1430. Antifoamselection: pH value; Temperature; Viscosity; Solid content.
Set-ups • Long term foaming stability and antifoam ability • SO2 removal efficiency • Gypsum quality wet FGD pilot plant Bikerman column (lab-scale)
Future work • Literature survey: foaming and defoaming • Investigation of foaming and wastewater treatment • Foaming and defoaming experimental investigations with selected additives • Duration ability of defoamers (long-term effects of defoamers) • Quantification of observed foaming and defoaming phenomena • Recommendations for full-scale use
Thank you for your attention ! Sea foaming