Application of hybrid coal reburning/SNCR processes for NOx reduction in a coal-fired boiler
- Zhejiang University, Hangzhou (China)
Boilers in Beijing Thermal Power Plant of Zhongdian Guohua Co. in China are coal-fired with natural circulation and tangential fired method, and the economical continuous rate is 410 ton per hour of steam. Hybrid coal reburning/SNCR technology was applied and it successfully reduced NOx to about 170 mg/Nm{sup 3} from about 540 mg/Nm{sup 3}, meanwhile ammonia slip was lower than 10 ppm at 450-210 t/h load and the total reduction efficiency was about 70%. Normal fineness pulverized coal from the bin was chosen as the reburning fuel and the nozzles of the upper primary air were retrofitted to be used as the reburning fuel nozzles. The reducing agent of SNCR was an urea solution, and it was injected by the four layer injectors after online dilution. At 410 t/h load, NOx emission was about 300 mg/Nm{sup 3} when the ratio of reburning fuel to the total fuel was 25.9%-33.4%. Controlling the oxygen content of the gas in the reversal chamber to less than 3.4% resulted in not only low NOx emission but also high combustion efficiency. Ammonia slip distribution in the down gas pass was uneven and ammonia slip was higher in the front of the down gas pass than in the rear of the down gas pass. NSR and NOx reduction were proportional to each other and usually resulted in more ammonia slip with reduction in NOx. About 100 mg/Nm{sup 3} NOx emission could be achieved with about 40 ppm NH{sub 3} slip at 300-450 t/h, and ammonia slip from the SNCR reactions could be used as reducing agent of SCR, which was favorable for the future SCR retrofit.
- OSTI ID:
- 21150646
- Journal Information:
- Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, Vol. 31, Issue 6; ISSN 1556-7036
- Country of Publication:
- United States
- Language:
- English
Similar Records
Integrated Dry NO{sub x}/SO{sub 2} Emissions Control System baseline SNCR test report, February 4--March 6, 1992
Evaluation of hybrid SNCR/SCR for NOx abatement on a utility boiler