Research: influence of air classification ratio on low nitrogen performance of natural gas burner

ABSTRACT

An innovative low-nitrogen natural gas burner was developed, leveraging air-staged combustion as the primary mechanism, supplemented by swirl combustion and flue gas recirculation technology. This design enables adaptation to a multitude of combustion conditions through the adjustment of the secondary air ratio. A prototype burner with a power output of 60 kW was constructed for experimental study. The velocity field, gas concentration field, temperature field, and NO_x concentration within the combustion zone were analyzed under different load, and the impact of the secondary air ratio on the burner’s low-nitrogen combustion performance was explored. Experimental results showed that the burner can maintain stable combustion and low NO_x emissions and had good load adaptability. The introduction of secondary air resulted in a “W”-shaped distribution characteristic within the combustion zone’s velocity and concentration fields, and effectively suppressed the formation of high-temperature zones, thereby reducing the generation of thermal NO_x. A secondary air ratio of 27% significantly enhanced the gas atmosphere within the combustion zone, leading to more uniform gas distribution and improved mixing of the gas mixture. Furthermore, it had a better low-nitrogen performance. With an increase in burner load, the NO_x concentration within the combustion zone also increased, reaching a peak value of 31 mg·m⁻³ at full-load, which still complied with low-nitrogen emission requirements.

KEYWORDS:

• Natural gas burner
• staged combustion
• low-nitrogen combustion
• NO_x
• experimental research

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Heng Chu

Heng Chu is a Master student in Xi’an Jiaotong University. He is interested in fuel clean combustion.

Feng Wu

Feng Wu received his Master degree from Xi’an Jiaotong University in 2023. He is interested in gas burner.

Yuping Huang

Yuping Huang is a Master student in Xi’an Jiaotong University. He focuses on pollution control.

Denghui Wang

Denghui Wang is an associate professor in Xi’an Jiaotong University. He focuses on fuel combustion and pollution control.