Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow
Abstract
:1. Introduction
2. Numerical Simulations
2.1. Mathematical Model Two-Fluid (Euler–Euler) Model
2.2. Population Balance Model
2.3. Aggregation Kernel Model
2.4. Boundary Conditions and Computational Method
3. Results and Discussion
3.1. Model Validation
3.2. Gas Velocity Distribution in a Cyclonic Spray Scrubber
3.3. Droplet Distribution
3.4. Particle Size Distribution under Different Conditions
3.5. Particle Removal Efficiency under Different Operating Conditions
3.5.1. Effect of Gas Flow Velocity on Particle Removal Efficiency
3.5.2. Effect of Spray Volume on Dust Removal Efficiency
3.5.3. Effect of Inlet Particle Concentration on Dust Removal Efficiency
4. Conclusions
- The velocity in the cyclonic spray scrubber is basically axisymmetric; that is, the velocity in the central region is the smallest, the velocity gradually increases along the radial direction from the center to the wall, and the velocity gradually decreases to zero near the wall boundary layer, exhibiting the characteristics of swirling flow. The volume concentration distribution of the droplet particles is hollow and conical, the central region is low, and the side wall region is high.
- As the flue gas flow velocity increases, the turbulent kinetic energy increases, and the efficiency of the turbulent aggregation of the particles increases. The particle size along the axial direction increases, the number density of the fine particles within each particle size interval decreases, and the removal efficiency gradually increases. The particle concentration at the outlet reaches the ultra-low emissions requirement of less than 5 mg/m3.
- As the spray flow rate increases, the number of droplets increases, the contact area between the droplets and air increases, the turbulent kinetic energy in the spray area increases, and the particle size increases significantly after wetting and agglomeration. The particle concentration in all of the size intervals at the outlet decreases, and the removal efficiency reaches 99.7%.
- As the particle concentration increases, the spacing between the particles decreases continuously, and the particles agglomerate more closely. However, due to the limited adsorption efficiency of the spray droplets, the removal efficiency of the fine particles reaches its highest value at 2 g/m3.
Author Contributions
Funding
Institutional Review Board Statement
Conflicts of Interest
References
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FPM Phase | Droplet Phase | ||
---|---|---|---|
Diameter (μm) | Volume Fraction | Diameter (μm) | Volume Fraction |
12.1 | 0.5 | 180 | 0.05 |
8.0 | 0.2 | 142 | 0.13 |
5.27 | 0.11 | 113 | 0.35 |
3.48 | 0.08 | 90 | 0.25 |
2.29 | 0.05 | 71 | 0.12 |
1.51 | 0.035 | 57 | 0.08 |
1.00 | 0.025 | 45 | 0.02 |
Velocity Comparison | Dust Concentration Comparison | ||||
---|---|---|---|---|---|
Simulated (m/s) | Measured (m/s) | Error (%) | Simulated (mg/m3) | Measured (mg/m3) | Error (%) |
0.08 | 0.075 | 6.25 | 9.519 | 9.583 | 0.67 |
2.16 | 2.08 | 3.70 | |||
6.52 | 6.34 | 2.76 |
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Qian, J.; Wang, J.; Liu, H.; Xu, H. Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow. Int. J. Environ. Res. Public Health 2022, 19, 16129. https://doi.org/10.3390/ijerph192316129
Qian J, Wang J, Liu H, Xu H. Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow. International Journal of Environmental Research and Public Health. 2022; 19(23):16129. https://doi.org/10.3390/ijerph192316129
Chicago/Turabian StyleQian, Jianghai, Junfeng Wang, Hailong Liu, and Haojie Xu. 2022. "Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow" International Journal of Environmental Research and Public Health 19, no. 23: 16129. https://doi.org/10.3390/ijerph192316129