超音速汲水虹吸气动雾化降尘技术

Supersonic siphon suction water aerodynamic atomization in dust removal

  • 摘要: 长期以来,煤炭行业受到高质量浓度呼吸性粉尘危害严重,常规湿式除尘方法针对性不足、捕集效率低、能耗高、可靠性差。为解决该问题,提出超音速汲水虹吸式气动喷雾降尘技术,并采用夫琅禾费衍射原理,测定其外雾场粒径分布;采用计算流体力学有限元方法,利用COMSOL软件SpalartAllmaras与液滴破碎雾化粒子追踪模块模拟研究了试验手段无法获得的喷管出口0~30 cm处的近场雾滴粒径、雾场速度分布特性。通过与超声波干雾抑尘技术的控尘对比试验,得出该技术的控尘特性、控尘机理;通过试验研究得到了不同工况参数、喷嘴出口锥度对雾化能耗和降尘速率的影响规律,研究结果表明:所设计雾化降尘装置,在低至0.2 MPa的气动压力下,达到负压汲水虹吸的微米级、高动力雾化效果。在气动压力为0.6 MPa时,雾场粒径分布范围为1.00~21.87 μm,喷嘴近场区域雾滴粒径10 μm以下的数量浓度占百微米以下的90%,5 μm以下的占80%;雾滴速度快、射程远,雾滴速度160 m/s以上的数量浓度占50%,50 m/s以上的占99%;耗气量与耗水量低,不同工况、开口锥度时,均随气动压力的增加而增大;喷雾角在60°~95°内,随喷嘴锥角的增大先增大后减小。降尘速率为超声波干雾抑尘方式的1.5倍,并随雾滴数量浓度、速度的增大而增加,瞬时效率提高了2%~26%;相同降尘效率时,采样滤膜上PM10以下粉尘占比减小24%;隔尘效果提高了10%。在敏东一矿06回风巷应用后,受到中心风速为0.86 m/s的风流扰动,依旧能将之穿透并覆盖全断面,对呼吸性粉尘的降尘效率达到了88.8%以上,证明该雾化系统可达到低湿、节水和高效的控尘效果。

     

    Abstract: High-concentration respiratory coal dust has remained as a serious hazard in the coal mining industry for a long time. The wet method currently used has many weaknesses, such as no clear targets, low efficiency of dust collection, high energy consumption and poor reliability. To solve the problems above, the dust reduction technology using supersonic suction siphon aerodynamic spray has been proposed in this study. The Fraunhofer diffraction principle is used to determine the particle size distribution of the external spray field. The near-field droplet size and the velocity distribution characteristics of spray field at the 0-30 cm distance to nozzle outlet, which cannot be obtained by experiments, are simulated and studied by using the CFD-FEM method, and the Spalart-Allmaras and droplet breaking particle tracking module of COMSOL software. Through the comparison experiments of dust control with ultrasonic dry spray dust suppression technology, the dust control characteristics and mechanism of the technology are obtained. With experimental research, the influence of different working condition parameters and nozzle outlet taper on atomization energy consumption and dust reduction rate are obtained. The results show that the designed atomization dust reduction device can achieve the micron-level, high-dynamic atomization effect of the negative pressure suction siphon process under the aerodynamic pressure as low as 0.2 MPa. At 0.6 MPa, the particle size distribution range is 1.00-21.87 μm, and the number of the droplets below 10 μm accounts for 90% of the total droplet number below 100 μm, and more than 80% below 5 μm. The droplet speed is fast and the range is large. The number concentration of the droplet speed above 160 m/s accounts for 50%, and above 50 m/s accounts for 99%. The air consumption and water consumption are low, and the spray angle is in the range of 60°-95°. The dust reduction rate is 1.5 times of that using the ultrasonic dry spray dust suppression, and it increases with the increase of the droplet concentration and speed, and the instantaneous efficiency is increased 2%-26%. At the same efficiency, the proportion of dust below PM10 reduced 24%. After being applied in the 06 return air way of Mindong No. 1 Mine, although it was disturbed by the wind flow with a central wind speed of 0.86 m/s, it still penetrated and covered the entire section, and the dust reduction efficiency for respiratory coal dust reached more than 88.8%. It is proved that the system can achieve low humidity, water saving and efficient dust control effects.

     

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