Experimental and Numerical Simulation Research on Different Shapes of Flame-Stabilizing Baffles in the Furnace
Abstract
:1. Preface
2. Surface Combustion and Aerodynamic Field Experiments
2.1. Boiler Experimental System Dimensions and Photos
2.2. Design of a Fully Premixed System
2.3. Full Premixed Combustion Experiment
3. Computational Details
3.1. Calculation Models and Equations
3.2. The Test Result of Grid Independence
4. Result and Discussion
4.1. Comparison of Experimental Values of Nonporous Baffles and Calculated Values of Various Baffles
4.1.1. Comparison of Experimental Values of O and CO When Installing Nonporous Baffles and without Baffles
4.1.2. Comparison of Calculated Values of CO Emissions
4.2. Comparison of Calculated Values of CO2 Emissions
4.3. Comparison of Calculated Values of Exhaust Gas Temperature
4.4. Comparison of Calculated Values of NOx Emissions
5. Conclusions
- (1)
- The installation of Nonporous baffles in the furnace and combustion experiments were conducted. The results showed that when installing a Nonporous baffle in the furnace, considering parameters such as exhaust temperature, boiler efficiency, and NOx emissions, the optimal excess air coefficients were 1.9, 2.0, and 2.1, respectively. Under the optimal operating conditions, the experimental values of NOx emissions were all below 30 mg/m3, and the net heat efficiency of the boiler was above 80%.
- (2)
- A comparative combustion experiment was conducted without or with the addition of a Nonporous baffle. The experimental results showed that as the gas volume increased, the optimal oxygen consumption increased, and the net heat efficiency of the boiler slightly increased. Under minimum, middle, and maximum firing rates, the CO content in the flue gas decreases, indicating that adding baffle is more beneficial for combustion. For the Nonporous baffle, the calculated values were compared with experimental values, and it was found that the minimum CO emission value was below 20 ppm. The maximum error between the calculated value and the experimental value is 6.8%, and the minimum error is 2.2%, indicating high calculation accuracy. Comparing the calculated values of the four types of baffles, it was found that the CO values in the flue gas were the lowest when installing the Strip baffle, and the exhaust temperature was also the lowest when installing the Strip baffle.
- (3)
- Comparing the average temperature values on different cross-sections along the axis of flue gas flow in the furnace under calculation conditions, different airflow fields lead to different temperature distributions. Among them, when installing a Strip baffle, the flue gas temperature drops the most after crossing the baffle and reaches the lowest value among the four types of baffles at the furnace outlet. The calculated NOx emissions are also the lowest among the four operating conditions at the corresponding positions, and the optimal operating condition calculation values are all below 40 mg/m3.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
Nomenclature
ρ | Fluid density; |
k | Turbulent kinetic energy equation; |
ε | Turbulent dissipation rate equation; |
μ | Dynamic viscosity; |
Mean fluid velocity; | |
Nonporous | Without holes; |
Strip | With bar holes; |
Round | With annular holes; |
Circular | With ring holes; |
Gk | Average velocity gradient generation term; |
Gb | Buoyancy generation term; |
YM | Pulse generation term; |
Yi | Component i pulse generation term; |
C1ε | 1.44; |
C2ε | 1.92; |
C3ε | Emprical constant; |
Sk/Sε | Souce items; |
Ri | Net generation rate of chemical reaction of component I; |
Si | The net generation rate obtained by adding the diffusion term to the user-defined source term; |
Ji | The diffusion flow rate generated by the i-th component due to concentration gradient; |
q | Water-cooled wall heat flux density, W/m2; |
Tw | Water-cooled wall temperature, K; |
Tf | Average flue gas temperature inside the furnace, K; |
hf | Convective heat transfer coefficient between water-cooled wall and flue gas; |
hint | Comprehensive heat transfer coefficient of convective radiation; |
Tint | Convection radiation comprehensive heat transfer temperature, K; |
qrad | Radiative heat transfer, W; |
G | Average heat release of high-temperature flames, W; |
εw | Surface emissivity of water-cooled walls. |
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Items | CH4 | C2H6 | C3H8 | N2 | Density /kg·Nm−3 | Wobbe Number /KJ·m−3 | Explosion Limit/% | Combustion Index | Calorific Value /MJ·Nm−3 |
---|---|---|---|---|---|---|---|---|---|
Natural gas | 95.346 | 2.936 | 0.535 | 1.183 | 0.74 | 52.44 | 5.0–15.1 | 39.3 | 35.7 |
Premixed Gas | Flue Gas Emission Index | Boiler Output and Efficiency | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Natural Gas Temperature /m3·h−1 | O2 /% | CO /ppm | CO2 /% | NO /mg·m−3 | NO2 /% | NOx /mg·m−3 | Exhaust Gas Temperature/°C | Smoke Pressure /pa | Steam Flow Rate /L·min−1 | Gross Efficiency /effg% | Net Efficiency /effn% |
100/ Minmum firing rate | 1.9 | 24 | 10.77 | 33 | 6 | 35.2 | 151.4 | 2.8 | 0.57 | 90.2 | 81.9 |
2.2 | 33 | 10.65 | 35 | 5 | 37.8 | 158.2 | 5.3 | 0.59 | 92.7 | 84.1 | |
2.4 | 32 | 10.37 | 40 | 5 | 42.6 | 160.3 | 16.8 | 0.57 | 92.8 | 84.2 | |
161/ Middle firing rate | 1.2 | 31 | 11.22 | 31 | 7 | 39.3 | 185.1 | 15 | 0.57 | 92.8 | 82.2 |
2 | 9 | 10.77 | 25.9 | 9 | 36.1 | 180.5 | 23 | 0.56 | 91.4 | 82.9 | |
2.2 | 24 | 10.65 | 35 | 4 | 38 | 205.2 | 57.2 | 0.57 | 90.6 | 82.1 | |
199/ Maximum firing rate | 2.1 | 9 | 12.82 | 21.2 | 5 | 26.9 | 200.8 | 58 | 0.55 | 90.4 | 82 |
2.2 | 12 | 12.16 | 31 | 6 | 33 | 211 | 63.1 | 0.56 | 90.3 | 81.9 | |
2.7 | 15 | 12.47 | 27 | 7 | 29 | 207 | 60 | 0.56 | 90.1 | 80.6 |
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Shi, H.; Yin, X.; Wang, C.; Wang, H. Experimental and Numerical Simulation Research on Different Shapes of Flame-Stabilizing Baffles in the Furnace. Energies 2024, 17, 4253. https://doi.org/10.3390/en17174253
Shi H, Yin X, Wang C, Wang H. Experimental and Numerical Simulation Research on Different Shapes of Flame-Stabilizing Baffles in the Furnace. Energies. 2024; 17(17):4253. https://doi.org/10.3390/en17174253
Chicago/Turabian StyleShi, Hongwei, Xiao Yin, Chunming Wang, and Haipeng Wang. 2024. "Experimental and Numerical Simulation Research on Different Shapes of Flame-Stabilizing Baffles in the Furnace" Energies 17, no. 17: 4253. https://doi.org/10.3390/en17174253
APA StyleShi, H., Yin, X., Wang, C., & Wang, H. (2024). Experimental and Numerical Simulation Research on Different Shapes of Flame-Stabilizing Baffles in the Furnace. Energies, 17(17), 4253. https://doi.org/10.3390/en17174253