Reduction of Unburned Carbon Release and NOx Emission from a Pulverized Wood Pellet Boiler Retrofitted for Fuel Switching from Coal

Energies

Yeong-gap Jeong¹  Changkook Ryu²  Jongkeun Park²  Seunghan Yu²  Jinje Park²  Hyunbin Jo²  Jiseok Lee² 

[1] Human Resource T/D Institute, Korea South-East Power Co., Jinju 52852, Korea;School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea;

关键词: wood pellet;    combustion;    unburned carbon;    NO_x emission;    wall-firing boiler;    computational fluid dynamics;   

DOI  :  10.3390/en13195077

来源: DOAJ

【 摘 要 】

For renewable electricity production, biomass can fully displace coal in an existing power plant with some equipment modifications. Recently, a 125 MWe power plant burning mainly anthracite in Korea was retrofitted for dedicated wood pellet combustion with a change of boiler configuration from arch firing to wall firing. However, this boiler suffers from operational problems caused by high unburned carbon (UBC) contents in the bottom ash. This study comprises an investigation of some methods to reduce the UBC release while achieving lower NO_x emissions. The computational fluid dynamics approach was established and validated for typical operating data. Subsequently, it was applied to elucidate the particle combustion and flow characteristics leading to the high UBC content and to evaluate the operating variables for improving the boiler performance. It was found that the high UBC content in the bottom ash was a combined effect of the poor fuel grindability and low gas velocity in the wide burner zone originating from the arch-firing boiler. This prevented the operation with deeper air staging for lower NO_x emissions. Reducing the particle size to <1.5 mm by modifying mills or pretreating the fuel using torrefaction was the only effective way of lowering the UBC and NO_x emissions with deeper air staging while increasing the boiler efficiency.

【 授权许可】

Unknown