Emission Characteristics and Visualization of an Axial-Fuel-Staged MILD Combustor. Issue 15 (18th November 2021)

• Record Type: Journal Article
• Authors: Zheng, Xianglong; Xiong, Yan; Liu, Yan; Lei, Fulin; Xiao, Yunhan
• Is Part Of: Combustion science and technology. Volume 193:Issue 15(2021)
• Page Start: 2588
• Page End: 2609
• Publication Date: 2021-11-18
• Subjects: MILD combustion -- axial-fuel-staged combustion -- NOx emissions -- opposed-flow flame analysis; Combustion -- Periodicals; Combustion engineering -- Periodicals; 541.36105
• DOI: 10.1080/00102202.2020.1751619
• Languages: English
• ISSNs: 0010-2202

Abstract

ABSTRACT: Axial-fuel-staged combustion is a promising approach to control NOx emission at high combustor outlet temperatures by shortening the residence time of burnt gas in high-temperature region. In this paper, an axial-fuel-staged MILD combustor was studied experimentally. The combustor consists of a first MILD burner producing hot burnt gases and a secondary transverse jet nozzle injecting premixed fuel and air mixtures. By varying the secondary stage equivalence ratio (Φ2 ) at several constant overall equivalence ratios (Φt ), NOx reduction (up to 35%) has been achieved at higher Φt but failed at lower Φt . And by increasing Φ2 at constant first stage equivalence ratios (Φ1 ), a continuous NOx emission increase was observed, which is insensitive to the variation of Φ1 . Furthermore, the liftoff behavior of the reaction region was also studied and it was found to play important roles in the dilution of the jet mixtures, as well as OH* intensities and NOx emissions. With the decrease of Φ1, the OH* chemiluminescence images present a decreased OH* intensity when Φ2 is lean but an increased OH* intensity when Φ2 is rich. Finally, an opposed-flow flame calculation was performed and the experimental results were well-supported by this numerical study.