Laphirattanakul, Ponepen

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Laphirattanakul, Ponepen
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Email
ponepen.la@kmitl.ac.th

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    Item type:Publication,
    Enhanced stability of pulverized biomass flames using an expanded primary port with bluff body
    (2026-01-01)
    Laphirattanakul, Ponepen
    ;
    Siripoom, Pongsakorn
    ;
    Keawchompoo, Chatchalerm
    ;
    Charoensuk, Jarruwat
    The impact of bluff body geometry combined with primary exit port expansion on the flame stability of a biomass pulverized fuel burner was investigated through numerical simulations. The expansions, applied at 1.25 and 1.5 times the original port size while maintaining a constant blockage ratio, were intended to reduce the momentum ratio between primary and secondary air streams. However, this adjustment concurrently led to a decrease in the swirl number, primarily due to the reduction in the secondary air exit area. Experimental results from the base case configuration were employed for model validation. Among the turbulence models considered, the SST k-ω model demonstrated the best agreement with experimental data in terms of temperature distribution and emission characteristics. The simulation results revealed that the base case exhibited flame anchoring behind the bluff body, supported by a pronounced reverse velocity region in its wake. Flame stability was also achieved in the 1.5SB case, attributed to a sufficiently reduced momentum ratio. This reduction enhanced the entrainment of the secondary air stream, promoting greater dispersion of fuel particles and enabling early-stage volatile combustion. The 1.5SB configuration achieved the highest temperature among all cases, reaching approximately 1150 °C. In contrast, the 1.25SB case exhibited flame blowout, resulting from a combination of reduced swirl number and an insufficient reduction in momentum ratio.
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    All parts overall heat transfer coefficients in correlation with design and off-design load conditions in a utility bagasse boiler
    (2025-01-15)
    Charoensuk, Jarruwat
    ;
    Lapirattanakun, Arwut
    ;
    Laphirattanakul, Ponepen
    Overall heat transfer coefficients of the four major sections in the 73 MW bagasse-fired boiler used in sugar industry were analyzed in correlation with the operating conditions. Comprehensive measurements were provided at different operating conditions including at design and off-design in relation to load generation and combustion performance on the firing grate. At the design condition, the overall heat transfer coefficients across the different sections, namely, the furnace, superheater, back tube and bank tube zones, were found uniformly within the range of 60–80 W/m<sup>2</sup>-K. Maintaining the overall heat transfer coefficient within this narrow range ensures that each section of the boiler is contributing optimally to the overall thermal efficiency. The optimal range of heat transfer coefficient in the furnace zone is within the range of 66–72 W/m<sup>2</sup>-K with 90 % of heat transfer in this zone occurring through radiation. While the high convection resulting from a high flue gas flow rate during off-designed condition leads to insufficient heat transfer in the furnace zone. Approximately 60 % of the heat uptake is instead absorbed by the bank tube section, which is strategically designed to capture the bypassed heat from the preceding section. It was also found that the overall radiative factor providing efficient heat transfer ranged from 0.48 to 0.63.
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    Development of pulverized biomass combustor with a pre-combustion chamber
    (2020-10-01)
    Laphirattanakul, Ponepen
    ;
    Charoensuk, Jarruwat
    ;
    Turakarn, Chinnapat
    ;
    Kaewchompoo, Chatchalerm
    ;
    Suksam, Niwat
    A 0.5 MW pre-combustion chamber for pulverized biomass burner was design based on a pulverized coal combustor design. The design concept, a 2D simulation guiding the construction and experimental results are discussed followed by an assessment of a 3D simulation. The difference in burning characteristics between coal and biomass were used to specify sizes of the air exits and the pre-combustion chamber. Simulation with pure biomass was used to guide fabrication of the test facility: the predicted temperature profiles suggested flame attachment within the specified operation range. Experimental results suggested that our design could achieve an anchoring flame as the measured temperature was above 800 °C within the pre-combustion chamber when operating between 0.3 and 0.5 MW. Maximum temperature at the last monitoring in the pre-combustion chamber was observed at 0.4 MW throughput, while the convection started to play negative impact at 0.5 M and the flame blow out occurred beyond this target. The 3D simulation under Reynolds-averaged Navier-Stokes assumption with its associated models agreed well with experiments which measured the axial temperature distribution in the pre-chamber. However, overestimation in the main combustion chamber suggested further improvement on model calibration as well as boundary conditions.