Efficiency study of low calorific value high momentum turbulent jet combustion flame

ABSTRACT

The industrial torch system is used to handle large amounts of flammable, toxic, and corrosive gases emitted during accidents or normal production processes. It utilizes open flames to burn off the gas pollutants. This study employs computational fluid dynamics (CFD) to investigate the combustion characteristics and efficiency of flames under high-velocity jet, aiming to address the issue of low combustion efficiency under high-velocity jet conditions. A three-dimensional flame model was established using methane and air as fuel, in order to investigate the variations and impact mechanisms of the combustion flame temperature field and carbon dioxide mass fraction distribution under different jet velocities, pilot component temperatures, and equivalence ratios. The reasons for low combustion efficiency under high-velocity jet conditions were analyzed. It was proposed to increase the combustion efficiency of the flame by raising the temperature of the pilot component, which differs from the traditional method of adding combustion-assisting gases. The combustion efficiency of flames under various operating conditions was evaluated. The results showed that as the jet velocity (v) increased from 49.6 m/s to 65 m/s, the height of the combustion flame in the vertical direction decreased continuously. Additionally, the high-temperature region at the center of the flame gradually decreased, leading to a 5.26% decrease in the highest flame temperature and a 3% decrease in combustion efficiency. When v  = 70 m/s, the high-velocity fuel flow penetrated the ignition source, causing a large amount of methane to escape into the atmosphere without combustion, resulting in flame extinction. Elevating the temperature (T) of the pilot component can reduce the impact of high-velocity jet on combustion efficiency. When T  = 2000 K, the flame reignites with a combustion efficiency of 94.1%. As the mass flow rate of the fuel composition inlet is reduced from 33.45 × 10⁻⁵ kg/s to 12.74 × 10⁻⁵ kg/s, the highest temperature of the combustion flame drops from 2072 K to 1451 K. As the equivalence ratio (φ) increases from 1.05 to 1.2, the height of the combustion flame in the vertical direction decreases continuously, resulting in a 0.7% decrease in the highest flame temperature and a 10.5% decrease in combustion efficiency.

KEYWORDS:

• Low calorific value gases
• Eddy Dissipation Concept (EDC)
• jet velocity
• temperature distribution
• equivalence ratio
• combustion efficiency

Disclosure statement

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

Credit author statement

- Peng Wang: Conceptualization; Writing – Original Draft; Simulation; Writing – Review & Editing.

- Dong Li: Resources; Funding acquisition; Project administration.

- Di Wang: Methodology; Data Curation.

- Yu Pu: Software.

- Yan Lv: Formal analysis.

- Kaiyi Luo: Validation.

Data availability statement

Data will be made available on request.

Additional information

Funding

This research was supported by the Heilongjiang Province’s Key Research and Development Project: “Leading the Charge with Open Competition” [No. 2023ZXJ06A04], the Heilongjiang Province “Double First Class” Discipline Collaborative Innovation Achievement Project [No. LJGXCG2023-108], the Heilongjiang Province College Student Innovation and Entrepreneurship Training Program Project [No. S202310220159], and the Northeast Petroleum University Undergraduate Innovation and Entrepreneurship Approval Project: “Leading the Charge with Open Competition” [No. 15011210702].

Notes on contributors

Peng Wang

Peng Wang received the B.S. degree in mechatronical and electrical engineering from Hebei Agricultural University, Baoding, China, in 2021. He is currently working toward the M.S. degree in energy and power engineering with the School of Mechanical Science and Engineering, Northeast Petroleum University, Daqing, China. His research interests include study of flame combustion characteristics and combustion efficiency.

Dong Li

Dong Li received the Ph.D. degree in engineering thermophysics from Harbin Institute of Technology, Harbin, China, in 2013. From April 2014 to July 2019, he held a postdoctoral position at Northeast Petroleum University, Daqing, China. He is currently a Full Professor and the Vice Dean of the School of Architecture and Civil Engineering, Northeast Petroleum University, Daqing, China. Prof. Li also acts as the committee member of the Thermal Utilization Professional Committee, China Renewable Energy Society. He has more than 210 publications, including journal articles, research reports, conference papers, and books. His current research interests are energy efficiency, multiphase flow measurement, and photothermal transmission characteristics of gas detection.

Di Wang

Di Wang received the B.S. degree in energy and power engineering from Yantai University, Yantai, China, in 2015, and the M.S. degree in power engineering from Northeast Petroleum University, Daqing, China, in 2019. He is currently working toward the Ph.D. degree in chemical engineering and technology with the School of Physics and Electronic Engineering, Northeast Petroleum University, Daqing, China. His research interests include flow field detection of combustion system and pollution emissions monitoring in oilfield standoff.

Yu Pu

Yu Pu received the B.S. degree in petroleum engineering from Northeast Petroleum University, Daqing, China, in 2014, and the M.S. degree in oil and gas engineering from China University of Petroleum Beijing, Beijing, China, in 2017. She is currently working toward the Ph.D. degree in oil and gas engineering with the School of Petroleum Engineering, Northeast Petroleum University, Daqing, China. Her research interests include simulation of porous scale multiphase flow and heat transfer in energy systems.

Yan Lv

Yan Lv received the Ph.D. degree in chemical engineering and technology from Northeast Petroleum University, Daqing, China, in 2022. She is currently an Associate Professor with School of Physics and Electronic Engineering, Northeast Petroleum University, Daqing, China. Her research interests include the monitoring of heavy oil thermal recovery parameters and the theory of tunable diode laser absorption spectroscopy.

Kaiyi Luo

Kaiyi Luo received the B.S. degree in electronic information science and technology from Jinggangshan University, Jian, China, in 2021. She is currently working toward the M.S. degree in optical engineering with the School of Physics and Electronic Engineering, Northeast Petroleum University, Daqing, China. Her research interests include flow field detection of combustion system and solar thermal utilization.