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An alternative to additional SO3 injection for fly ash conditioning.
D J Bayless1, A R Khan, S Tanneer
1Department of Mechanical Engineering, Ohio University, Athens, USA. bayless@ohio.edu
Journal of the Air & Waste Management Association (1995)
|February 19, 2000
Summary
This study demonstrates a novel method to convert sulfur dioxide (SO2) to sulfur trioxide (SO3) using a natural gas flame, enhancing fly ash conditioning in coal-fired power plants without external SO3 addition.
Area of Science:
- Environmental Engineering
- Chemical Engineering
- Combustion Science
Background:
- Electrostatic precipitators (ESPs) utilize sulfur trioxide (SO3) for efficient particulate collection, particularly with low-sulfur coal.
- Current methods of SO3 addition incur costs and have negative environmental impacts.
Purpose of the Study:
- To explore an alternative method for in-situ SO3 generation from existing sulfur dioxide (SO2) in flue gas.
- To improve fly ash conditioning for enhanced particulate collection in coal-fired power plants.
Main Methods:
- Utilized a drop-tube furnace with a pre-mixed natural gas flame to facilitate SO2 to SO3 conversion.
- Investigated gas temperatures of 450 K and 1000 K.
- Measured SO3 concentrations via wet chemistry and confirmed with elemental balances of other sulfur species using gas chromatography.
Main Results:
- Achieved up to 7% homogeneous conversion of SO2 to SO3.
- Observed decreased SO3 back-conversion rates at lower temperatures, extending SO3 availability for ash conditioning.
- Speculated increased flue gas humidity as an additional benefit.
Conclusions:
- A natural gas flame effectively converts SO2 to SO3 in flue gas, offering a cost-effective and environmentally conscious alternative to external SO3 injection.
- The process enhances fly ash conditioning, improving ESP performance.
- Low-temperature operation prolongs the efficacy of the generated SO3.