Effects of gas stream temperature on homogeneous SO{sub 2} to SO{sub 3} conversion via natural gas reburning
- Ohio Univ., Athens, OH (United States). Dept. of Mechanical Engineering
Homogeneous superequilibrium of SO{sub 3} forms when SO{sub 2} passes through a flame in the presence of excess O{sub 2}. Because SO{sub 3} is more reactive with metal sorbents than SO{sub 2}, potential advantages of higher SO{sub 3} concentrations include lower fly ash resistivity, which could increase particulate removal in electrostatic precipitators, and improved performance of dry scrubbing systems. While the superequilibrium phenomenon has been studied, little data exist about the effects of free stream gas temperature (as opposed to flame temperature) on the process in the temperature range found downstream of economizers in pulverized-coal fired plants. Using information from prior studies by other researchers, a free stream temperature in the 450--1,000 K range could theoretically reduce the concentration of free-stream O radicals and reduce the thermal decomposition rate of SO{sub 3}. Consequently, a lower gas temperature could extend the duration of the transient superequilibrium effect beyond what has previously been observed. A pre-mixed methane flame was used to promote the conversion of SO{sub 2} to SO{sub 3} inside 1.25- and 4-inch drop tubes at free stream temperatures between 450 and 1,000 K. Experimental results from solid sampling and SO{sub 2}/SO{sub 3} measurements via wet chemistry coupled with numeric modeling of species concentrations and reactions indicate that lower free stream temperatures reduce the maximum conversion of SO{sub 2} to SO{sub 3}, but considerably extend the duration of the superequilibrium effect. Results also indicate that higher excess oxygen levels are necessary for this conversion in large-volume spaces compared to smaller flow areas. Further, decomposition of SO{sub 3} may be much more important to the overall balance of SO{sub 2}/SO{sub 3} (compared to the reduction of SO{sub 3} via interaction with oxygen and hydrogen radicals) than previously reported.
- OSTI ID:
- 349166
- Report Number(s):
- CONF-980985-; ISBN 1-890977-15-2; TRN: IM9924%%166
- Resource Relation:
- Conference: 15. annual international Pittsburgh coal conference, Pittsburgh, PA (United States), 14-18 Sep 1998; Other Information: PBD: 1998; Related Information: Is Part Of Fifteenth annual international Pittsburgh coal conference: Proceedings; PB: [1500] p.
- Country of Publication:
- United States
- Language:
- English
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