切流型旋流接触元件流场特性分析

发布时间：2018-05-21 00:31

本文选题：旋流接触元件 + 压降　；参考：《大连理工大学》2016年硕士论文

【摘要】：化工行业的不断发展使得传统塔板难以满足实际生产的需要,因此本文以高效率、高通量、高操作弹性为目标,在前人隔离降液结构的优势上,提出一种新型塔板元件——切流型旋流接触元件。塔器内,气体切向进入旋流元件,在叶片的导向和渐缩流道的加速作用下,形成高度的旋流流场；同时塔板上的液体由进液管直接导入旋流中心,被旋流流场分散破碎成液滴,在与气相进行传质传热接触的同时被分离至管壁,最终在气相的推动下液体到达侧缝后被甩出,从而实现塔板上气液两相先接触后分离的过程。本文讨论了最小流通面积与叶片参数的关系,利用三维建模软件建立了不同参数的旋流接触元件模型,并用商业软件Fluent对其流场进行模拟,计算表明6个叶片的结构具有更大的切向速度,且压降适中,流场分布比较均匀；此外,在不引起旋流流场显著变化的条件下,侧缝的设计宽度为10mm,长度为65mm。本文根据模拟优化结果,加工了新型元件,并搭建试验平台对其进行气液两相实验,得到了压降与操作参数的关系。实验表明,压降主要取决于气相流量,且与流量的平方成线性关系,而液相流量的变化只引起压降的小幅波动。然后,进一步的实验收集了该旋流接触元件的负荷性能曲线,表明其液相下限流量维持在较低水平,液相上限主要受侧缝排液能力的限制,降液管液泛气量在600 m3/h以上,而发生雾沫夹带的气量随着液量的增大而逐渐降低。旋流接触元件的阀孔动能因子的变化范围在8.6～24.7之间,远高于普通塔板；其气相操作弹性大于2,液相的最大变化范围可达20,分离效果良好,基本实现了提高处理量的要求。此外,针对特定工况,利用VOF模型进行了气液两相流场的模拟,结果显示液相在进液管出口首先形成液膜,接着被撕裂吹散成不同粒径的液滴的运动机制,并且发现发生漏液的原因在于气体无法将液膜运送至排液口所造成,并非流场旋流强度不足而导致,为后续优化改进提供了参考。结合模拟和实验结果,本文设计的切流型旋流接触元件具有高通量、高弹性的特点。
[Abstract]:The continuous development of chemical industry makes it difficult for the traditional trays to meet the needs of actual production. Therefore, this paper aims at high efficiency, high throughput and high operating elasticity, and has the advantage of isolating the down-liquid structure. A new type of tray element-tangent swirl contact element is proposed. In the tower, the gas tangentially enters the swirl element and forms a high swirl flow field under the guide of the blade and the acceleration of the tapered passage. At the same time, the liquid on the tray is directly introduced into the swirl center by the inlet tube, and is dispersed into droplets by the swirl flow field. At the same time, the liquid was separated into the tube wall while the gas phase was in contact with the gas phase. Finally, the liquid reached the side slit and was thrown out under the promotion of the gas phase, thus realizing the process of the gas-liquid two-phase contact and then separating on the tray. In this paper, the relationship between the minimum flow area and the blade parameters is discussed. The swirl contact element model with different parameters is established by using 3D modeling software, and the flow field is simulated by commercial software Fluent. The results show that the six blades have larger tangential velocity, moderate pressure drop, and uniform flow field distribution. In addition, the design width and length of the side joint are 10mm and 65mm without significant variation of the swirl flow field. Based on the results of simulation and optimization, a new type of element was fabricated, and the gas-liquid two-phase experiment was carried out on a test platform, and the relationship between pressure drop and operating parameters was obtained. The experimental results show that the pressure drop mainly depends on the flow rate of the gas phase and is linearly related to the square of the flow rate, while the change of the flow rate of the liquid phase causes only a small fluctuation of the pressure drop. Then, the load performance curves of the hydrocyclone contact element are collected in further experiments. The results show that the lower liquid flow rate is maintained at a lower level, and the liquid upper limit is mainly limited by the side slit discharge capacity, and the liquid flooding volume of the downflow tube is above 600 m3 / h. However, the amount of gas entrainment decreases with the increase of liquid content. The variation range of the kinetic energy factor of the valve hole of the swirl contact element is between 8.6 and 24.7, which is much higher than that of the common tray, and the gas phase operation elasticity is more than 2, the maximum range of liquid phase variation can reach 20, the separation effect is good, and the requirement of increasing the processing capacity is basically realized. In addition, the VOF model is used to simulate the gas-liquid two-phase flow field. The results show that the liquid phase first forms a liquid film at the outlet of the liquid inlet and then is torn and dispersed into droplets of different sizes. It is also found that the leakage is caused by the gas being unable to transport the liquid film to the outlet, which is not caused by the insufficient swirl intensity of the flow field, which provides a reference for further optimization and improvement. Combined with the simulation and experimental results, the tangential swirl contact element designed in this paper has the characteristics of high throughput and high elasticity.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ053.5

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