Influence of Uneven Secondary Air Supply and Burner Tilt on Flow Pattern, Heat Transfer, and NOx Emissions in a 500 MWe Tangential-Firing Coal Boiler

Hyunbin Jo, Jongkeun Park, Woosuk Kang, Junseok Hong, Sungmin Yoon, Howon Ra and Changkook Ryu
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Hyunbin Jo: School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
Jongkeun Park: School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
Woosuk Kang: School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
Junseok Hong: R&D Center, Korea Western Power Co., Ltd., Daejeon 35377, Korea
Sungmin Yoon: Korea Institute of Energy Research (KIER), Daejeon 34129, Korea
Howon Ra: Korea Institute of Energy Research (KIER), Daejeon 34129, Korea
Changkook Ryu: School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea

Energies, 2021, vol. 14, issue 24, 1-18

Abstract: Tangential-firing boilers develop large swirling fireballs by using pulverized coal and air from the corners of the burner zone. During operation, however, the boiler may experience an uneven air supply between corners; this deforms the fireball, raising various issues concerning performance and structural safety. This study investigated the characteristic boiler performance and the role of burner tilting in a 500 MWe boiler with secondary air (SA) in two corners that are up to 1.9 times larger than those in the other corners. Computational fluid dynamics simulations with advanced coal combustion sub-models were employed with the following two sets of cases: (i) six cases of actual operation to validate the modeling and (ii) sixteen cases for the parametric study of SA flow ratio and burner tilt between −15° and +26°. The results showed that the uneven SA supply deteriorated the boiler performance in various aspects and the burner tilt can be used to alleviate its impact. With a larger SA supply from the left wind box, the mass flow, heat absorption, and O 2 concentration were larger in the right half of the heat exchanger sections owing to the rotating flow. The corresponding imbalance in the reaction stoichiometry increased the peak temperature entering the tube bundles by up to 60 °C and NO emissions by 6.7% as compared with normal operations. The wall heat absorption was up to 19% larger on the right and front walls. The high burner tilt of +26° helped alleviate the impact of uneven SA supply on the heat distribution and uniformity of the flow pattern and temperature, whereas a +15° burner tilt was the least favorable.

Keywords: coal combustion; tangential-firing; burner tilt; secondary air; NOx emission (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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