磁場形式及參數對單纖維捕集鋼鐵行業粉塵中PM<sub>2.5</sub>性能影響

張儷安; 刁永發; 莊加瑋; 周發山; 沈恒根

doi:10.13374/j.issn2095-9389.2019.02.24.004

磁場形式及參數對單纖維捕集鋼鐵行業粉塵中PM_2.5性能影響

doi: 10.13374/j.issn2095-9389.2019.02.24.004

東華大學環境科學與工程學院，上海 201620

基金項目: 國家重點研發計劃資助項目（2018YFC0705300）；中央高校基本科研業務費重點資助項目（2232017A-09）

詳細信息

通訊作者:
E-mail: diaoyongfa@dhu.edu.cn

中圖分類號: TF701.3
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出版歷程
- 收稿日期: 2019-02-24
- 刊出日期: 2020-02-01

Performance of single fiber collection PM_2.5 under different magnetic field forms in the iron and steel industry

School of Environmental Science and Engineering College, Dong Hua University, Shanghai 201620, China

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Corresponding author: E-mail: diaoyongfa@dhu.edu.cn

摘要

摘要: 目前鋼鐵行業已成為大氣污染防治的重點，為解決現有鋼鐵行業對于PM_2.5細顆粒難以捕集的難題，實現粉塵的超低排放。基于CFD-DPM（computational fluid dynamics-discrete phase model）方法對磁性纖維產生的磁場以及高梯度磁場等不同磁場形式下單纖維對鋼鐵行業捕集PM_2.5性能的影響進行研究，通過X射線衍射圖譜分析可知鋼鐵行業生產過程產生的粉塵因含有Fe₃O₄以及單質Fe而具有磁特性，進而提出了利用磁場來增強單纖維捕集PM_2.5性能的方法. 計算結果表明，在運動軌跡方面，磁性纖維產生的磁場會在纖維周圍形成引力區，高梯度磁場會在纖維周圍形成2個引力區和2個斥力區；在捕集性能方面，當粉塵粒徑d_p為0.5～1.0 μm，入口風速v≤0.2 m·s^?1時，高梯度磁場下磁性纖維的捕集能力要強于單一磁性纖維的捕集能力，若磁場強度H=0.5 T，磁感應強度B=0.01 T，v=0.1 m·s^?1，高梯度磁場可以使單纖維的捕集效率提高為傳統單纖維捕集的28.32倍，若B=0.01 T，v=0.1 m·s^?1，磁性纖維產生的磁場可以使捕集效率提高為傳統單纖維捕集的4.037倍；在磁性纖維產生的磁場中，當磁感應強度B≥0.03 T時，磁性單纖維對PM_2.5的捕集效率隨著入口風速的增加而減小，后趨于穩定，當B<0.03 T時，捕集效率隨入口風速逐漸減小；捕集效率隨粉塵粒徑的增加而增大. 而對于高梯度磁場，單纖維對PM_2.5捕集效率同樣隨著入口風速的增加而減小，當v>0.4 m·s^?1時，捕集效率為0，B越大，捕集效率下降越快；捕集效率隨著粉塵粒徑增大呈現先增加后減小的趨勢.
- 磁性纖維 /
- 高梯度磁場 /
- PM_2.5 /
- 鐵磁性 /
- 捕集性能
Abstract: At present, the steel industry has become the focus of air pollution prevention and control. To solve the difficulty in collecting PM_2.5 fine particles and achieving ultra-low emission of dust, based on the method of computational fluid dynamics-discrete phase model (CFD-DPM), the influence of different magnetic field forms, such as magnetic field generated by magnetic fiber and high-gradient magnetic field, on the performance of PM_2.5 collection in the iron and steel industry was studied. Through X-ray diffraction (XRD) analysis, it was found out that the dust produced in the iron and steel industry production process has magnetic characteristics due to the presence of Fe₃O₄ and elemental Fe, furthermore, the method of using magnetic field to enhance the PM_2.5 collection performance of single fiber was proposed. The results show that the magnetic field generated by the magnetic fiber will form a gravitational region around the fiber, and the high-gradient magnetic field will form two gravitational regions and two repulsive regions around the fiber. In terms of the collection ability, when particle diameter d_p between 0.5 and 1.0 μm, inlet velocity v≤0.2 m·s^?1, the collection ability of magnetic fiber under the high-gradient magnetic field is stronger than that of the single magnetic fiber. If magnetic field intensity H=0.5 T, magnetic induction intensity B=0.01 T, and v=0.1 m·s^?1, the high-gradient magnetic field can improve the single fiber collection efficiency by 28.32 times as much as the original; if B=0.01 T, v=0.1 ms^?1, the magnetic field generated by the magnetic fiber can improve the single fiber collection efficiency by 4.037 times as much as the original. In terms of the collection law, in the magnetic field generated by the magnetic fiber, when the magnetic flux density B≥0.03 T, the collection efficiency of magnetic single fiber on PM_2.5 decreases with the increase of inlet velocity speed and then tends to be stable. When B<0.03 T, the collection efficiency decreases with the inlet velocity speed. The collection efficiency increases with the increase of dust particle size. For the high-gradient magnetic field, the single fiber collection efficiency of PM_2.5 particles also decreases with the increase of inlet velocity speed. When v>0.4 ms^?1, the collection efficiency is 0. The larger B is, the faster the collection efficiency decreases. The collection efficiency increases first and then decreases with a increase in dust particle size.
- magnetic fiber /
- high-gradient magnetic field /
- PM_2.5 /
- ferromagnetism /
- collection performance

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圖 1 鋼鐵廠排放粉塵的動態光散射技術測試結果

Figure 1. DLS test results of dust emission from steel works

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圖 2 鋼鐵廠排放粉塵的X射線衍射圖譜

Figure 2. XRD pattern of dust emission from steel works

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圖 3 不同纖維濾料的電鏡掃描形貌. （a） PPS；（b） FMS；（c） PSA；（d） P84

Figure 3. SEM images of different fiber filter materials: (a) PPS; (b) FMS; (c) PSA; (d) P84

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圖 4 計算區域及邊界條件設置圖. （a） P84纖維電鏡掃描；（b）單纖維模型計算邊界條件

Figure 4. Calculation area and boundary condition setting diagram: (a) P84 fiber SEM image; (b) single fiber model used to calculate the boundary conditions

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圖 5 不同形式磁場示意圖. （a）粉塵顆粒被纖維捕集區域示意圖；（b）無磁場；（c）磁性纖維產生的磁場；（d）高梯度磁場

Figure 5. Schematics of different magnetic fields: (a) area where PM_2.5 dust particles are collected by fibers; (b) no magnetic field; (c) magnetic field generated by magnetic fiber; (d) high-gradient magnetic fields

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圖 6 網格獨立性檢驗

Figure 6. Mesh independence test

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圖 7 數值模擬值與經驗公式對比

Figure 7. Comparison between numerical simulation values and empirical formula

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圖 8 3種工況下PM_2.5的運動軌跡（v=0.1 m·s^?1， d_p=1.0 μm）。（a）無磁場；（b）磁性纖維產生的磁場；（c）高梯度磁場

Figure 8. PM_2.5 movement trajectory under three working conditions: (a) no magnetic field; (b) magnetic field generated by magnetic fiber; (c) high-gradient magnetic fields

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圖 9 不同磁場形式下PM_2.5捕集效果對比

Figure 9. Comparison of PM_2.5 trapping effects under different magnetic field forms

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圖 10 不同入口風速與捕集效率關系圖（d_p=1.0 μm）. （a）磁性纖維產生的磁場；（b）高梯度磁場

Figure 10. Relation between different inlet velocity speeds and collection efficiencies (d_p=1.0 μm): (a) magnetic field generated by magnetic fiber; (b) high-gradient magnetic field

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圖 11 不同入口風速下粉塵在磁場中的運動軌跡（d_p=1.0 μm）. （a）磁性纖維產生的磁場B=0.05 T；（b）高梯度磁場H=0.5 T，B=0.05 T

Figure 11. Movement trajectory of dust in magnetic field at different inlet velocity speeds (d_p=1.0 μm): (a) magnetic field generated by magnetic fiber (B=0.05 T); (b) high-gradient magnetic field (H=0.5 T, B=0.05 T)

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圖 12 不同粒徑與捕集效率關系圖（v=0.1 m·s^?1）. （a）磁性纖維產生的磁場；（b）高梯度磁場

Figure 12. Relation between particle size and collection efficiencies (v=0.1 m·s^?1): (a) magnetic field generated by magnetic fiber; (b) high-gradient magnetic field

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圖 13 不同粒徑粉塵在磁場中的運動軌跡（v=0.1 m·s^?1）.（a）磁性纖維產生的磁場（B=0.05 T）；（b）高梯度磁場（H=0.5 T，B=0.05 T）

Figure 13. Movement trajectory of dust with different particle sizes in magnetic field (v=0.1 m·s^?1): (a) magnetic field generated by magnetic fiber (B=0.05 T); (b) high-gradient magnetic field (H=0.5 T, B=0.05 T)

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