Open Access

ARTICLE

Numerical Study on Operation Optimization of Low NOx Combustion Characteristics of Swirl Impact Gas Burner

Zhenjie Yuan, HaiLong Yu^*, Hongjun Cao
School of Petroleum and Natural Gas Engineering, School of Energy, Changzhou University, Changzhou 213164, China
* Corresponding Author: HaiLong Yu. Email:

Energy Engineering https://doi.org/10.32604/ee.2025.076483

Received 21 November 2025; Accepted 18 December 2025; Published online 06 January 2026

Abstract

Low-NOx combustion of natural gas is essential for cleaner industrial heat supply under increasingly strict emission regulations. However, many existing low-NOx swirl burners still rely on single-mechanism control and suffer trade-offs between temperature suppression, combustion stability, and mixing uniformity. This work develops and numerically optimizes a structurally integrated cyclonic-impingement natural-gas burner that combines four rows of impinging secondary-air jets with four axially deflected main fuel nozzles, realizing a coupled swirl-impingement-staging mechanism that differs fundamentally from conventional swirl burners employing only geometric swirl or simple air staging. Validated three-dimensional RANS CFD simulations (realizable k-ε turbulence model, steady diffusion flamelet combustion, and DO radiation), after grid-independence testing and comparison with literature data, are used to quantify the effects of burner load, primary/secondary air ratio, excess air coefficient, and air-preheating temperature on the furnace thermal field, flow structures, and NOx distribution. The results show that the proposed burner maintains ultra-low-NOx operation with outlet concentrations below 50 mg·m⁻³ over the entire operating range, while preserving complete and stable combustion. A primary-to-secondary air ratio of 2:8 and an excess air coefficient of about 1.05 provide an optimal compromise between combustion intensity and emission control, and operation with approximately ambient-temperature air (≈300 K) is recommended when NOx reduction is prioritized. Within the investigated parameter space, the simulated NOx levels fall within or below the ranges reported for low-NOx swirl burners in the literature, while offering a structurally distinct solution based on integrated swirl-impingement-staging. These findings highlight the practical potential of the proposed integrated design as a compact ultra-low-NOx option for upgrading industrial gas-fired combustion systems to cleaner operation.

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Keywords

Swirl impact gas burner; ultra-low NOx emission; numerical simulation

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