高操作参数旋风分离器旋流流场相似放大与模化的研究

Chemical industry development needs to go through scale-up process, while large scale manufaction provides useful feedback to the model and process design, both involving similar amplification and modeling basic problems in chemical process. The swirling flow is an important basic flowing pattern for the process intensification in the industrial field by means of its forming centrifugal force field. The operation and structure parameters of cyclone equipment has upgraded towards to high parameters. Research on swirl flow’s characteristics under high parameter (high temperature, high pressure, large scale, high load or high particle concentration) cyclone research is insufficient due to the reason that the experimental data are very difficult to be obtained under the condition of supernormal parameters and lack of fundeamental understanding of the similarity scale-up and modleing methods about swirling flow. This resulted the complexity and misunderstanding due to the inadequate theory between industrial application and process design. The results usually is very difficult to be explained reasonably and mostly lead to arbitrary process design method mainly depends on empirial experience and results. Thus it is urgent to elucidate the fundamental theory which would help reducing the experimental workload, saving money and development time. For this purpose, this project choose cyclone separator as the research object and focus on the the similarity scale-up and modeling method of the swirling flow equipment. Firstly, the swirling flow field is measured as varying pressure, temperature, dimension, flow rate and inlet concentration. Then the similarity number groups are deduced based on the mechanics of supernormal parameters effecting on the flow field. The dimensionless number relation is built between the swirling flow flied and supernormal parameters, which will be applied to predict the swirling flow peformance used in industrial process. Further more, through the experimental measurement and CFD simulation of the swirling flow field in a cyclone separator under the supernormal parameter conditions including gas phase field and gas-solid two phase field, the foundmental relationship between the swirling flow field and supernormal parameters can be established. Finally, the obtained similarity number groups can be used to discribe the characteristics of the swirling flow field. Evatually the similarity scale-up and modeling method will be developed for swirling flow field. The results will provide the fundamental theroy and guide for the process equipment design and improvement.

化工开发经放大才能工业化，工业又为放大设计提供反馈，两者涉及相似放大模化基本问题。能形成超重力场强化传质分离过程的旋流是流体流动基本形式之一。常温常压旋流特性研究较多，但旋流设备的操作、结构参数向高参数拓展。高参数（高温、高压、大尺度、高负荷或高颗粒浓度）旋流研究仍缺乏实验数据和理论计算，更缺乏相似放大模化方法。导致设计、应用中问题很难合理解释，处理方法依赖经验，盲目性大。故急需相关研究，建立系统科学理论,减少逐级放大工作量、资金、时间, 意义重大。本课题以旋风分离器旋流为对象，通过高参数旋流实验、数值模拟，建立反映旋流特点的新准数群，拓展准数范围，创建普适旋流相似放大模化理论模型，实现用模型预测高参数旋流工业原型性能。分析高参数对旋流流场影响，构建两者准数模型。考察气相、气固相旋流流场自模特性，进行旋流流场相似放大与模化关键理论研究。为涉及旋流过程改进、设备设计提供相似放大模化理论基础。

旋转流形成的超重力场是强化传质分离过程的基本形式之一。高参数（高温、高压、大尺度、高负荷或高颗粒浓度）的旋转流研究仍缺乏实验数据和理论计算，也缺乏相似放大模化方法，导致涉及旋转流的单元操作设计方法、应用中问题处理等具有很大的经验性。.课题以PV型高流量旋风分离器为对象，首先以流动参数变化（改变入口速度和入口浓度）对旋风分离器分离效率和压降及流场进行实验测量。在实验基础上采用RSM模型，改变流量参数和尺寸参数进行旋风分离器的全空间流场计算。以不同直径相似旋风分离器，在相同入口气速下计算无量纲切向速度。对相同直径旋风分离器，改变温度参数和压力参数，以及选择不同KA和Dr参数，计算无量纲切向速度。通过旋风分离器模型与原型的无量纲切向速度，考察旋转流场的相似性，并以此分析旋转流的自模特性。当入口速度>20 m/s，或压力>3 MPa，或直径>2000 mm，流场的欧拉数与雷诺数不相关，模型与原型流场处于自模区。否则，流场的相似性较差，流场处于非自模区。.对Ø300mm旋风分离器旋转流瞬态流场的测量表明，旋转流的瞬时切向速度存在较大的脉动特性，是由高频湍流脉动和低频的波动组成。低频的波动速度是旋转流的中心摆动造成的，即旋转流在自转的同时，旋转中心围绕几何中心做随机摆动。旋转流的湍流强度在r/R > 0.4区域较小，r/R <0.4区域，湍流强度的急剧增加。.在气固两相流存在的条件下，旋风分离器模型与原型之间的相似放大与模化涉及的准数有：St，Re，Fr，ρp /ρg，di /dm，dm /D，Ci /ρg等，其中St和Re是主要影响参数。若流场处于近似自模区，可以不考虑Re。若流场处于非自模区，速度场需要进行修正。最后通过St不变量进行模型与原型之间的性能计算，求得模型与原型的颗粒临界粒径比值d50m /d50p，依据模型的结果可以预测原型的性能。