Control of coal combustion SO{sub 2} and NO{sub x} emissions by in-boiler injection of CMA. Sixth quarterly project status report, 1 January 1994--31 March 1994
Conclusions: 1. Impregnation of pulverized coal particles by CMA and CA (and to leser extent MA) was found to increase the combustion temperature of both the volatile and the char phases. Effects of the additives on the burntime of either of the two phases could not be clearly detected. 2. The pretreatment of pulverized (75-90{mu}m) and micronized (3.5{mu}m mean) and beneficiated coals with CMA, CA or MA (at a Ca/S = 2) substantially reduced the emission of SO{sub 2}, at gas temperatures between 1250 to 1450 K, followed by a cool-down zone, in fuel-lean combustion ({phi} = 0.35-0.57). 3. The combustion of CMA-, CA-, or MA-treated pulverized coal in normal air suggested that all three sulfur caption mechanisms, mentioned in the introduction, were evident in the present experiments. 4. The results of experiments in normal air and in atmospheres containing 40% oxygen suggested that the release and subsequent sulfation of CaO and MgO aerosols may be the main mechanism for sulfur removal in the virtually ash-free micronized coal that was treated with CMA. 5. NO{sub x} emissions were increased with higher gas temperatures. Micronized coal produced 25% less NO{sub x} than pulverized coal. This could be due to its lower nitrogen content and slightly more fuel-rich conditions for the micronized coal combustion, as well as localized fuel-rich conditions surrounding the small particles as the volatiles and char burn together. 6. The emissions of NO{sub x} from CMA-treated pulverized coal were similar to those from untreated coal, whereas CMA-treated micronized coal released slightly more NO{sub x} than it did when untreated. The latter event may be caused by the added fuel oxygen associated with the effective penetration of the CMA additive.
- Research Organization:
- Northeastern Univ., Boston, MA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-92PC92535; FG22-89PC89776
- OSTI ID:
- 10157559
- Report Number(s):
- DOE/PC/92535-T6; ON: DE94013067; BR: AA1525050; AA1525050
- Resource Relation:
- Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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