脉冲喷吹清灰高湿粉尘剥落的数学模型研究

Mathematical model of high-humidity dust peeling during pulse-jet cleaning

  • 摘要: 为了使滤料振动特性与除尘器清灰参数最优配合,探究粉尘从滤料上剥落的条件,建立了脉冲喷吹清灰时高湿粉尘从滤料上剥落的数学模型:附着力< 剥离力,对附着在滤料表面上的细粉尘所受的附着力以及脉冲喷吹清灰时滤料振动对细粉尘产生的剥离力进行研究。直径小于50 μm的细粉尘,附着力主要受范德华力和液桥力的影响,脉冲喷吹振动产生的反向加速度影响剥离力的大小。通过建立脉冲喷吹清灰时滤料的振动方程,采用拉普拉斯变换求解振动方程,得出壁面峰值压力与反向加速度的关系; 根据粉尘剥落的数学模型求解出粉尘剥落时壁面峰值压力的范围,对0.15,0.20,0.25 MPa喷吹压力时不同工况的脉冲喷吹实验进行模型验证。结果表明,剥离力大于附着力时,高湿粉尘会从滤料上剥落,粉尘的剥落情况影响清灰效果的好坏; 根据粉尘剥落的数学模型对剥离力进行计算得到最大反向加速度的变化规律,从而得出粉尘剥落时壁面峰值压力的变化规律,根据给定参数计算得出剥离力大于附着力时壁面峰值压力大小为306 Pa; 对比脉冲喷吹实验0.15,0.20,0.25 MPa时不同工况的实验结果发现,0.20,0.25 MPa时的壁面峰值压力均大于306 Pa,同时对附粉滤料进行脉冲喷吹实验,测得粉尘的剥离率为92.55%,92.8%。研究结果为改善高湿粉尘的脉冲清灰效果提供借鉴。

     

    Abstract: In order to make the vibration characteristics of the filter material and the parameters of the dust remover cooperate optimally, and investigate the condition of dust peeling off from filter material, the mathematical model of high-humidity dust peeling off from the filtration material by pulse-jet cleaning was established:adhesion force< peeling force.The adhesion force of fine dust attached to the surface of the filtration material and the peeling force produced by the vibration of filter material during pulse-jet cleaning were studied.For the fine dust with a diameter of less than 50 μm, the adhesion force is mainly influenced by van der Waals force and liquid bridge force.The opposite acceleration generated by pulse-jet vibration affects the magnitude of the peeling force.By establishing the vibration equation of filter material under pulse-jet cleaning, which was solved by Laplace transform technique, the relationship between the peak pressure of the wall and the opposite acceleration was obtained.According to the mathematical model of dust peeling, the range of peak pressure on the wall surface was solved when dust peeling off.Finally, the model was verified by the pulse-jet experiment under different working conditions at injection pressure of 0.15, 0.2, 0.25 MPa respectively.The results show that when the peeling force is greater than the adhesion force, the high-humidity dust peels off from the filter material, and the flaking of dust affects the effect of ash cleaning.According to the mathematical model of dust peeling, the variation of the maximum opposite acceleration was obtained by calculating the peeling force, and then the variation law of the wall peak pressure at the time of dust spalling was obtained, and it was calculated according to the given parameters that the peak pressure of the wall is 306 Pa when the peeling force is greater than the adhesion.Comparing with the experimental results of different working conditions in the pulse injection test of 0.15, 0.2, 0.25 MPa, it was found that the peak pressure of the wall at 0.2 and 0.25 MPa was greater than 306 Pa.Meanwhile, in the pulse jetting test on the powder filter material, the dust removal rate is 92.55% and 92.8%.The research results have theoretical and practical significance for improving the pulse cleaning effect of high-humidity dust.

     

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