非均匀颗粒气力提升的实验研究

发布时间：2018-10-23 21:33

【摘要】：气力提升作为一种新兴技术,在矿浆提升、河道清淤、石油和化工液体输送等领域中广泛应用。其常规特性已得到较为深入的研究,但非均匀介质的气力提升理论涉猎较少。针对于此,本文提出采用气力提升非均匀颗粒的构想,从实验角度入手,结合理论建模揭示其提升机理。为研究颗粒提升规律,根据牛顿第二定律和流体力学基本理论,建立了颗粒提升临界模型,获得临界速度随粒径的变化趋势。在此基础上,根据动量守恒定律和多相流理论建立提升管内气液固三相流速度模型,分析管内轴向压力、各相相含率和真实速度的分布规律,从而得出气、液、固三相折算速度的关系,进一步分析粒径、颗粒浓度和浸入率等参数对提升性能的影响规律。此外,基于能量守恒定律建立提升效率模型,分析进气量、浸入率和颗粒浓度等因素的相互作用机制及其对效率的影响规律。为验证理论模型的可靠性,以粒径为2mm和5mm的麦饭石陶瓷颗粒为介质,实验研究不同进气量QG、浸入率γ、粒径dS、颗粒浓度αS和颗粒混合比δ下,扬水量QL、扬固量QS和提升效率η的变化规律。理论分析与实验测试结果表明:临界速度随颗粒尺寸增大而增大,随浸入率升高而减小。而在实验中则发现临界气量值随浸入率上升呈递减趋势,随颗粒尺寸增大呈上升趋势。扬固量和提升效率均随浸入率升高而增高,随粒径增大而下降,存在最佳气量值使得扬固量与提升效率处于峰值。扬固量随颗粒浓度增加而上扬,但提升效率则与之相反。在恒定颗粒浓度下,扬固特性和提升效率随混合比的增大(细颗粒含量增多)而上扬;粗颗粒受浸入率的影响较细颗粒大。理论分析与实验结果相吻合。
[Abstract]:As a new technology, Pneumatic lifting is widely used in the fields of slurry lifting, river desilting, petroleum and chemical liquid transportation. The conventional characteristics have been deeply studied, but the pneumatic lifting theory of inhomogeneous medium is less. In this paper, the idea of lifting non-uniform particles with pneumatic force is put forward, and the lifting mechanism is revealed from the point of view of experiment and theoretical modeling. In order to study the law of particle lifting, according to Newton's second law and the basic theory of fluid mechanics, the critical model of particle lifting is established, and the variation trend of critical velocity with particle size is obtained. Based on the momentum conservation law and the multiphase flow theory, the velocity model of gas-liquid-solid three-phase flow in the riser is established, and the distribution of axial pressure, phase holdup and real velocity in the pipe are analyzed, and the gas and liquid are obtained. The effect of particle size, particle concentration and immersion rate on the lifting performance was analyzed. In addition, based on the law of conservation of energy, an efficiency model is established to analyze the interaction mechanism of air intake, immersion rate and particle concentration and its effect on efficiency. In order to verify the reliability of the theoretical model, the immersion ratio 纬 of QG, the concentration of dS, particles 伪 S and the mixing ratio 未 of dS, particles of different air intake were studied in the medium of Mailanshi ceramic particles with diameter of 2mm and 5mm. The variation law of QL, lift amount QS and lift efficiency 畏. The theoretical analysis and experimental results show that the critical velocity increases with the increase of particle size and decreases with the increase of immersion rate. In the experiment, it is found that the critical gas volume decreases with the increase of immersion rate and increases with the increase of particle size. Both the lifting rate and the lifting efficiency increased with the increase of the immersion rate and decreased with the increase of the particle size. The amount of lifting solid increased with the increase of particle concentration, but the efficiency was opposite. Under the constant particle concentration, the lifting characteristics and lifting efficiency increased with the increase of mixing ratio (the content of fine particles), and the influence of the infiltration rate of coarse particles was greater than that of fine particles. The theoretical analysis is in agreement with the experimental results.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD53

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