【作者】 胡施俊；

【导师】 胡大鹏；

【作者基本信息】 大连理工大学 ， 安全技术及工程， 2009， 硕士

【摘要】 超音速旋流分离技术利用超音速流动条件下气体的低温凝结效应结合旋流分离技术实现多组分气体中凝点较高组分的冷凝分离,整个过程集制冷、冷凝和分离过程于一体,具有结构简单,占地面积小,无转动件,等熵效率高等优点,在天然气脱水净化等混合气体分离领域具有广阔的应用前景。但是该项技术还存在轴向速度高,离心分离不充分的缺点。为了克服上述缺点,诞生了将超音速旋流分离技术与涡流效应相结合的两相涡流管分离技术。针对两相涡流管分离特性,本文提出了超音速喷嘴涡流管技术,对超音速喷嘴和其他部件进行了结构设计。通过对超音速喷嘴涡流管内部气体的流动行为的数值分析,预测出该装置可以实现混合气体的分离。建立了实验平台,以空气—乙醇蒸汽的混合气体为介质,对超音速喷嘴涡流管的混合气体分离性能进行了实验研究,并且得到了操作和结构参数对分离性能的影响趋势。为提高超音速喷嘴涡流管的混合气体分离性能,采用了外加凝结核心辅助蒸汽凝结的方法增大凝结液滴尺寸。通过对非均质成核理论的研究,对外加凝结核心的选取要求进行了分析,得到了外加核心为与混合气体中重组分互溶、不发生化学反应且挥发度相对很小的微小液滴。采用离散相模型对液滴在超音速喷嘴涡流管中的运动状态进行了分析,并且预测了该装置的结构和操作参数对装置分离性能的影响趋势。以空气—乙醇蒸汽的混合气体为介质、微小水滴为外加凝结核心,对采用增大凝结液滴方法后超音速喷嘴涡流管的混合气体分离性能进行了研究。实验结果表明,采用增大凝结液滴方法后,装置的分离性能得到一定程度的提高,重组分脱除率和露点降最大值为32.70%和20.87K,可分别提高17.83%和3.55K。此外,对采用增大凝结液滴后操作和结构参数对装置分离性能的影响进行了研究,得到的影响趋势与数值预测结果一致。更多还原

【Abstract】 The supersonic gas separation technology is a novel gas mixture separation technology appeared in recent years.In the supersonic gas separation process,heavy components of gas mixture condense under the low-temperature condition created by supersonic gas flow itself and then separated from gas phase by the centrifugal force caused by the self-rotation of two -phase flow.This technology conducts expansion,cyclone gas/liquid separation and re-compression in a compact,tubular device with no rotating part,with the advantage including simple structure,small occupied space,low energy consumption and investment cost,and high isentropic efficiency etc.Thus,it has wide application foreground in the gas mixture separation area such as dehydration and purification of Natural Gas.However,the supersonic state of gas flow in the separation section shortens the contact and separation time of gas and condensed droplets,leading to the infaust effect on the separation performance.To overcome this shortcoming,the separation technology based on the two-phase vortex tube is proposed,combining the supersonic gas separation technology and vortex flow effects together.On the basis of two-phase vortex separating technology,a new vortex structure with supersonic nozzles is proposed.A numerical model has been established to simulate the flow behavior of gas flow in this new type of vortex tube.The numerical results indicate that the mixed gas can be separated by the new device.An experimental platform is set up to investigate the separation performance of the new device and the influential trend of operational and structural parameters on the separation performance are found out.In order to improve the performance of vortex tube with supersonic nozzle for mixed gas separation,the condensed droplet size is enlarged by adding nucleation centers.Based on the heterogeneous nucleation theory,the adoption requirements of additional nucleation centers are analyzed.Finally,the added nucleation centers are determined,i.e.micro-droplets with lower volatility which are soluble and not reacted with heavy component.Using Discrete Phase Model,the movement states of injected droplets in the vortex tube are analyzed and the influences of operational and structural parameters on the separation performance are also predicted. The gas mixture separation performance of vortex tube with supersonic nozzle using droplet enlargement method is experimentally researched.The medium is air-ethanol steam mixture and the external condensation nucleuses are micro water drops.Experimental results shows that the separation performance of the equipment is improved by a certain degree using the droplet enlargement method.The maximums of the heavy component removal rate and the dew point depression are 33.73%and 17.8K,increased by 17.85%and 3.55K respectively. Furthermore,the effects of the operational and structural parameters on the separation performance is studied,and the influence trend consistent well with the numerical prediction.更多还原