This study experimentally investigates the gas-particle two-phase flow characteristics of an old-model burner (OMB) and a new-type swirl-stabilized combustor (NTSTC) designed for a 350 MW opposed-fired coal boiler. Using a particle dynamic anemometry (PDA) system, the three-dimensional velocity field, turbulence intensity, and particle volume flux at the burner outlet were measured at nominal load cases spanning 20% - 100%. The results show that the NTSTC forms a distinct central recirculation zone (RZ) in the near-nozzle region (x/d = 0.1 - 0.5), where the axial velocity exhibits a bimodal distribution and the radial velocity indicates centripetal particle movement near r/d ≈ 0.2. These characteristics persist at low loads and promote particle residence and central accumulation. Compared with the OMB, the NTSTC exhibits higher turbulence intensity within central RZ and stronger gas-particle mixing, including 20% load. The particle volume flux results further demonstrate central particle enrichment and particle backflow within the RZ. Overall, the NTSTC provides more favorable near-field gas-particle flow organization and better aerodynamic adaptability to load variation. The present study is limited to cold-flow measurements; combustion efficiency, gas composition, and NOx emissions were not directly evaluated.
References
[1]
Zhang, Y.Z., Wu, Q.W., Zhu, Y.F., Kang, X., Hou, B.J. and Zhou, H. (2024) Experimental Study on the Effects of Co-Firing Mode and Air Staging on the Ultra-Low Load Combustion Assisted by Water Electrolysis Gas (HHO) in a Pulverized Coal Furnace. JournaloftheEnergyInstitute, 117, Article 101828. https://doi.org/10.1016/j.joei.2024.101828
[2]
Liu, T., Wang, Y.G., Zou, L., Bai, Y.Y., Shen, T., Wei, Y.W., Li, F.X. and Zhao, Q.X. (2024) Numerical Investigation of Stable Combustion at Ultra-Low Load for a 350 MW Wall Tangentially Fired Pulverized-Coal Boiler: Effect of Burner Adjustments and Methane Co-Firing. AppliedThermalEngineering, 246, Article 122980. https://doi.org/10.1016/j.applthermaleng.2024.122980
[3]
Wei, D.N., An, D., Wang, T., Zhang, H.C., Guo, Y.H. and Sun, B.M. (2023) Influence of Fuel Distribution on Co-Combustion of Sludge and Coal in a 660 MW Tangentially Fired Boiler. AppliedThermalEngineering, 227, Article 120344. https://doi.org/10.1016/j.applthermaleng.2023.120344
[4]
Huang, C.C., Li, Z.Q., Lu, Y., Chen, Z.C., Liu, H.C., Kang, Y.Y. and Wu, W. (2024) Research on a Novel Universal Low-Load Stable Combustion Technology. Energy, 310, Article 133223. https://doi.org/10.1016/j.energy.2024.133223
[5]
Wang, Q.X., Chen, Z.C., Li, L.K., Zeng, L.Y. and Li, Z.Q. (2020) Achievement in Ultra-Low-Load Combustion Stability for an Anthracite-and Down-Fired Boiler after Applying Novel Swirl Burners: From Laboratory Experiments to Industrial Applications. Energy, 192, Article 116623. https://doi.org/10.1016/j.energy.2019.116623
[6]
Zhang, H.L., Lin, H., Zhou, X., Wang, X.B., Zheng, H.G., Liu, Y. and Tan, H.Z. (2024) CFD Modeling and Industry Application of a Self-Preheating Pulverized Coal Burner of High Coal Concentration and Enhanced Combustion Stability under Ultra-Low Load. AppliedThermalEngineering, 253, Article 123831. https://doi.org/10.1016/j.applthermaleng.2024.123831
[7]
Jin, W., Si, F.Q., Kheirkhah, S., Yu, C., Li, H.Y. and Wang, Y.O. (2023) Numerical Study on the Effects of Primary Air Ratio on Ultra-Low-Load Combustion Characteristics of a 1050 MW Coal-Fired Boiler Considering High-Temperature Corrosion. AppliedThermalEngineering, 221, Article 119811. https://doi.org/10.1016/j.applthermaleng.2022.119811
[8]
Li, Z.Q., Liu, Z., Huang, H.L., Du, H. and Chen, Z.C. (2024) The Effects of Key Parameters on the Gas/Particle Flows Characteristics in the Furnace of a Foster Wheeler Down-Fired Boiler Retrofitted with Novel Low-Load Stable Combustion Technology. Energy, 288, Article 129736. https://doi.org/10.1016/j.energy.2023.129736
[9]
Wang, Z.Z., Zhang, L., Zhao, Y.Y., Feng, S., Ma, J., Kong, W.W., Shen, B.X. and Sun, R. (2021) Experimental Investigation on the Evolution Characteristics of Anthracite-N and Semi-Coke Reactivity under Various O2/H2O Pre-Oxidation Atmospheres. FuelProcessingTechnology, 216, Article 106725. https://doi.org/10.1016/j.fuproc.2021.106725
[10]
Wang, Y.Q., Zhou Y.G., Bai, N.M. and Han, J.C. (2020) Experimental Investigation of the Characteristics of Nox Emissions with Multiple Deep Air-Staged Combustion of Lean Coal. Fuel, 280, Article 118416. https://doi.org/10.1016/j.fuel.2020.118416
[11]
Hui, J.C., Zhu, S.J., Li, Z.Y., Lin, J.G., Cao, X.Y. and Lyu, Q.G. (2024) Experimental Study on Peak Shaving during Preheating Combustion for Different Coal Ranks: Thermal Modification and Variable Load Operation. Fuel, 373, Article 132324. https://doi.org/10.1016/j.fuel.2024.132324
[12]
Ma, D.F., Zhang, S.Y., He, X., Ding, X., Li, W.F. and Liu, P.Y. (2024) Combustion Stability and NO Emission Characteristics of Three Combustion Modes of Pulverized Coal Boilers under Low or Ultra-Low Loads. AppliedEnergy, 353, Article 121998. https://doi.org/10.1016/j.apenergy.2023.121998
[13]
Yuan, Z.H., Chen, Z.C., Wu, X.L., Zhang, N., Bian, L.G., Qiao, Y.Y., Li, J.W. and Li, Z.Q. (2022) An Innovative Low-Nox Combustion Technology for Industrial Pulverized Coal Boiler: Gas-Particle Flow Characteristics with Different Radial-Air-Staged Levels. Energy, 260, Article 125142. https://doi.org/10.1016/j.energy.2022.125142
[14]
Zhao, L.L., Zhou, Q.T. and Zhao, C.S. (2008) Flame Characteristics in a Novel Petal Swirl Burner. CombustionandFlame, 155, 277-288. https://doi.org/10.1016/j.combustflame.2008.04.012
[15]
Yan, R., Chen, Z.C., Zheng, Y., Yuan, L.X., Zeng, L.Y. and Li, Z.Q. (2021) Influence of Inner and Outer Secondary Air Ratio on Flow and Combustion Characteristics of a Swirl Burner in a 29 MW Pulverized Coal Boiler. Energy, 237, Article 121625. https://doi.org/10.1016/j.energy.2021.121625
[16]
Su, X.Q., Fang, Q.Y., Ma, L., Yao, B., Li, Y., Zhao, X.P., Mao, R. and Yin, C.G. (2023) Improving Combustion and Lowering NO Emissions of an Industrial Coal Swirl Burner by Optimizing Its Nozzle Structure. AppliedThermalEngineering, 218, Article 119340. https://doi.org/10.1016/j.applthermaleng.2022.119340
[17]
Song, M.H., Huang, Q., Niu, F. and Li, S.Q. (2020) Recirculating Structures and Combustion Characteristics in a Reverse-Jet Swirl Pulverized Coal Burner. Fuel, 270, Article 117456. https://doi.org/10.1016/j.fuel.2020.117456
[18]
Ti, S.G., Chen, Z.C., Li, Z.Q., Zhang, X.Q., Zhang, H., Zou, G.P., Zeng, L.Y. and Zhu, Q.Y. (2015) Effects of the Outer Secondary Air Cone Length on the Combustion Characteristics and NO X Emissions of the Swirl Burner in a 0.5 MW Pilot-Scale Facility during Air-Staged Combustion. AppliedThermalEngineering, 86, 318-325. https://doi.org/10.1016/j.applthermaleng.2015.04.021
[19]
Su, X.Q., Jiang, J.L., Ma, C.L., He, Y.C. and Yang, Z.F. (2025) High-Efficiency Combustion and Low-Nitrogen Emission of Coal-Fired Boiler Based on Synergistic Optimization of Swirl Burner Structure and Air-Staged Technology. Fuel, 388, Article 134352. https://doi.org/10.1016/j.fuel.2025.134352
[20]
Huang, C.C., Li, Z.Q., Wang, Y.F., Fang, F., Liu, H.C., Chen, Z.C. and Liu, Y.J. (2024) Influence of Secondary Air Blade Angle and Oxygen-Rich Combustion Characteristics of an Improved Babcock Swirl Burner. AppliedThermalEngineering, 241, Article 122383. https://doi.org/10.1016/j.applthermaleng.2024.122383
[21]
Wang, Y.Q. and Zhou, Y.G. (2020) Numerical Optimization of the Influence of Multiple Deep Air-Staged Combustion on the Nox Emission in an Opposed Firing Utility Boiler Using Lean Coal. Fuel, 269, Article 116996. https://doi.org/10.1016/j.fuel.2019.116996
[22]
Lee, B.H., Song, J.H. and Kim, R.G. (2010) Simulation of the Influence of the Coal Volatile Matter Content on Fuel NO Emissions in a Drop-Tube Furnace. Energy&Fuels, 24, 4333-4340. https://doi.org/10.1021/ef1003792
[23]
Song, W.H., Ouyang, Z.Q., Wang, M.H., Li, S.Y., Liu, J.Z., Yu, Q., Liu, W. and Zhu, Q.Y. (2020) The Combustion and Nox Emission Characteristics of the Ultra-Low Volatile Fuel Using the Novel Pulverized Coal Self-Sustained Preheating Combustion Technology. Fuel, 271, Article 117592. https://doi.org/10.1016/j.fuel.2020.117592
[24]
Wang, Q.X., Chen, Z.C., Chen, Q.W., Zeng, L.Y. and Li, Z.Q. (2019) Experimental Investigation of Gas/Particle Two-Phase Flow Characteristics in a Down-Fired Boiler by PDA Measurements. ExperimentalThermalandFluidScience, 107, 38-53. https://doi.org/10.1016/j.expthermflusci.2019.05.014
[25]
Wang, Q.X., Chen, Z.C., Han, H., Tu, Y.J., Liu, G.K., Zeng, L.Y. and Li, Z.Q. (2019) Detailed Gas/Particle Flow Characteristics of an Improved Down-Fired Boiler with Respect to a Critical Factor Affecting Coal Burnout: Vent-Air Inclination Angle. Energy, 182, 570-584. https://doi.org/10.1016/j.energy.2019.06.057
[26]
Pickett, L.M., Jackson, R.E. and Tree, D.R. (1999) LDA Measurements in a Pulverized Coal Flame at Three Swirl Ratios. CombustionScienceandTechnology, 143, 79-107. https://doi.org/10.1080/00102209908924194
[27]
Zhang, X., Chen, Z.C., Hou, J., Liu, Z., Zeng, L.Y. and Li, Z.Q. (2022) Evaluation of Wide-Range Coal Combustion Performance of a Novel Down-Fired Combustion Technology Based on Gas-Solid Two-Phase Flow Characteristics. Energy, 248, Article 123662. https://doi.org/10.1016/j.energy.2022.123662
[28]
Ren, F., Li, Z.Q., Chen, Z.C., Xu, Z.X. and Yang, G.H. (2010) Experimental Investigations into Gas/Particle Flows in a Down-Fired Boiler: Influence of the Vent Air Ratio. Energy&Fuels, 24, 1592-1602. https://doi.org/10.1021/ef901243c
[29]
Lira, S.H., Torres, M.J., Guerra, S.R. and Zahr, V.J. (2021) Numerical Characterization of the Solid Particle Accumulation in a Turbulent Flow through Curved Pipes by Means of Stokes Numbers. AppliedSciences, 11, Article 7381. https://doi.org/10.3390/app11167381
[30]
Fan, W.D., Lin, Z.C., Li, Y.Y. and Li, Y. (2010) Effect of Temperature on NO Release during the Combustion of Coals with Different Ranks. Energy&Fuels, 24, 1573-1583. https://doi.org/10.1021/ef901198j
