USC 보일러에서 혼합연료별 적정 과잉 공기비

Abstract

경제성장에 발맞춰 국내 전력수급역시 꾸준히 증가해 왔고 보일러 설계기술 역시 향상되어 500 MW이상의 대용량 초초임계압(USC; Ultra super critical) 발전소가 다수 운영되고 있다. 하지만 보일러 연료인 유연탄을 전량 수입하는 운영특성상 국제석탄가격 상승 및 발전사간의 경쟁으로 인해 원가절감을 위한 석탄 공급원의 다변화, 저가 아역청탄 공급 등으로 보일러 설계 시와는 다른 연소조건을 가지게 되었고 달라진 연소환경에 따라 적정 과잉공기비를 찾아 효율향상을 이루어내는 것이 필요하게 되어 본 연구에서는 USC보일러인 당진화력 8호기를 대상으로 혼합연료별 과잉공기비 변화시험을 통한 효율을 산정하고 그 결과로 적정 과잉공기비를 구하였다. 본 연구를 통해 Macquarie-Powder river 5:5 혼합연료 연소시와 Sonoma-Megaprima persada 5:5 혼합연료 연소시의 적정과잉공기비는 13%이고 BHP Billiton-Powder river 4:6 혼합연료 연소시와 Centennial-Batubara 3:7 혼합연료 연소시의 적정과잉공기비는 11%임을 알 수 있었다. |The power supply in Korea has increased to match the nation's economic growth. Due to the advanced boiler design, ultra super critical (USC) power plants with a capacity of 500 MW or over are in operation. Given the fact that the entire bituminous coal used for boiler is imported, the supply of coal is often affected by the rise of international coal price. Moreover, coal suppliers have been diversified due to the competition among power generation companies for reducing costs and inexpensive sub-bituminous coal is used. As a result, boilers combustion conditions have been deviated from the initial boiler design. This requires the selection of adequate excessive air ratio for different combustion conditions to enhance the efficiency of boiler operation. In this study, the boiler efficiency has been identified through an examination on the change of excessive air ratio by mixed fuel in unit 8 of Dangjin power plant complex. In addition, an excessive air ratio was calculated based on the examination result. According to the study result, the adequate excessive air ratio was 13% when Macquarie and Powder river were mixed at a ratio of 5:5 and when Sonoma and Megaprima persada were mixed at a ratio of 5:5. Moreover, when BHP Billiton and Powder river were mixed at a ratio of 4:6 and Centennial and Batubara were mixed at a ratio of 3:7, the adequate excessive air ratio was 11%.; The power supply in Korea has increased to match the nation's economic growth. Due to the advanced boiler design, ultra super critical (USC) power plants with a capacity of 500 MW or over are in operation. Given the fact that the entire bituminous coal used for boiler is imported, the supply of coal is often affected by the rise of international coal price. Moreover, coal suppliers have been diversified due to the competition among power generation companies for reducing costs and inexpensive sub-bituminous coal is used. As a result, boilers combustion conditions have been deviated from the initial boiler design. This requires the selection of adequate excessive air ratio for different combustion conditions to enhance the efficiency of boiler operation. In this study, the boiler efficiency has been identified through an examination on the change of excessive air ratio by mixed fuel in unit 8 of Dangjin power plant complex. In addition, an excessive air ratio was calculated based on the examination result. According to the study result, the adequate excessive air ratio was 13% when Macquarie and Powder river were mixed at a ratio of 5:5 and when Sonoma and Megaprima persada were mixed at a ratio of 5:5. Moreover, when BHP Billiton and Powder river were mixed at a ratio of 4:6 and Centennial and Batubara were mixed at a ratio of 3:7, the adequate excessive air ratio was 11%.