Transcript Analysis and quantification of foaming phenomena in wet FGD

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
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
Introduction
The wet scrubber FGD process is the most widespread desulphurisation technology.
DTU Chemical Engineering
Technical University of Denmark
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
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
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
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
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.
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
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
DTU Chemical Engineering
Technical University of Denmark
Source: Siemens AG 2007
5
CHEC Annual Day 2010, October 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.
Antifoam selection:
pH value;
Temperature;
Viscosity;
Solid content.
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
Set-ups
•Long term foaming stability and antifoam ability
•SO2 removal efficiency
•Gypsum quality
Bikerman column (lab-scale)
DTU Chemical Engineering
Technical University of Denmark
wet FGD pilot plant
CHEC Annual Day 2010, October 5
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
DTU Chemical Engineering
Technical University of Denmark
CHEC Annual Day 2010, October 5
Thank you for your attention !
DTU Chemical Engineering
Technical University of Denmark
Sea foaming
CHEC Annual Day 2010, October 5