【作者】 李虎林；

【导师】 巨永林；

【作者基本信息】 上海交通大学 ， 制冷及低温工程， 2011， 博士

【摘要】 本论文针对一氧化碳（CO）低温精馏分离稳定同位素¹³C这一热量、质量、动量耦合传递体系进行了详细的试验及模拟研究。主要包括低温精馏装置工艺设计及试验测试、新型高效丝网波纹填料的开发及性能测试、低温精馏流程模拟优化及填料内CO汽-液两相流动模拟分析。具体内容如下:（一）基于热量衡算、物料衡算、真空计算,设计了一套采用一氧化碳低温精馏分离稳定同位素¹³C的工艺流程。针对¹³C低温分离流量小、低温绝热要求高的特殊要求,提出并设计研制了多层绝热的低温精馏塔结构专利技术;开发了高比表面积丝网波纹填料及锯齿形波纹填料专利技术,满足低温精馏分离稳定同位素¹³C的工艺要求;设计研制了低温精馏分离同位素¹³C的控制方案,建立了国内第一座采用CO低温精馏分离同位素¹³C的试验装置。（二）采用空气-水冷模实验及对/邻二甲苯二元混合体系热模实验,测试了峰高1.6、2.0、2.5 mm三种规格的高比表面积丝网波纹填料的流体力学性能及传质性能。得到了三种规格填料的Leva压降关联式、Bain-Houzen液泛点关联式、动持液量关联式;通过试验得到了高效规整不锈钢金属丝网规整填料的传质性能数据,可以推广到CO低温精馏分离同位素¹³C中。（三）详细的实验测试结果表明,本文建立的CO低温精馏试验装置当气体动能因子F在0.26-0.53m/s（kg/m3）1/2时,试验每米理论板数为25-28块。试验装置的全回流平衡时间为4天、开车浓缩时间为23-30天、极限浓缩达到15%¹³C、达到了年产500克10%¹³C的生产能力。本文开发的新型高比表面积丝网波纹规整填料比传统填料具有更好的分离能力,其单位比表面积分离功和单位比表面积理论板数均超过了国外同类装置的2倍以上。（四）通过对¹²C¹⁶O-¹³C¹⁶O-¹²C¹⁸O三元组分同位素体系低温精馏过程的稳态及动态模拟研究,对影响¹³C同位素分离的因素进行了数值模拟计算。单因素稳态模拟分析表明,塔压的降低、回流比的增加、气体动能因子的降低有利于提高产品丰度。通过均匀实验设计得出,对于建立的精馏塔,蒸发功率为250 W时,优化设计的操作条件为操作压力为54 kPa,回流比为84。而低压力、高回流比有利于降低本试验装置的操作能耗。动态模拟结果表明,增大进料量、增大再沸器功率有利于缩短平衡时间。（五）建立了表征波纹填料单元结构的三维物理模型。通过CFD模拟计算表明,在两相逆流的精馏过程中,传统的波纹填料由于结构缺陷表面大部分没有被液体流覆盖,液体在填料表面呈溪流流动。液体分布不均主要内在原因是由填料结构导致,而与填料层的高度无关。数值模拟证实了“雾沫夹带”的现象。本文提出了基于持液量的“传质液泛点”概念,用于确定高比表面积丝网波纹填料的有效传质区间。新开发的锯齿形波纹填料在结构上采用直角三角形通道,比传统波纹填料具有更优良的液体分布性能以及提供更多的汽、液界面。这种具备更高传质效率的锯齿形波纹填料可推广到常规化工精馏塔中,取代传统波纹填料。更多还原

【Abstract】 In this dissertation, the processes of carbon monoxide （CO） cryogenic distillation for the separation of stable isotopes ¹³C, in which the momentum, heat, and mass transfer are highly coupled, were systematically studied by experimental test and numerical simulation. The main contents included the system design and experimental test of the cryogenic distillation process, the development and performance measurement on the special packing, the process simulation on the distillation column and the two-phase CFD simulation inside the special packing. The major works were summarized as followings:1.A process flow of stable isotopes ¹³C separation by CO cryogenic distillation was designed after heat calculation, material calculation, and vacuum computation. The technology of multilayer adiabatic rectifying tower was designed and manufactured, meeting up with the adiabatic requirements of small flow, low temperature in distillation; The high specific corrugated gauze packing and corrugated Zigzag-pak were developed, satisfying the requirement of enriching stable isotopes ¹³c by cryogenic distillation process; Auto-control solution of the cryogenic distillation process was designed and constructed; and the first domestic CO cryogenic distillation pilot for separation isotope ¹³c was set up.2.Through the cold mould experiments of air–water and the hot model experiment of p/o-xylene mixed system, the fluid dynamic properties and mass transfer performances were measured for three types of corrugated gauze packing with peak height of 1.6, 2.0, and 2.5 mm respectively. The empirical formulas of Leva pressure drop, Bain-Houzen liquid flooding point, and dynamic liquid holdup were obtained. The mass transfer data of the test packing were also measured by hot model experiments, which can be used in CO cryogenic distillation for the separation of ¹³C.3.Based on the experimental measurements, it is proven that the theoretical plates per meter of the proposed packing are from 25 to 28 with the F-factor of 0.26 to 0.53 m/s （kg/m3）1/2, the balance time are 4 days at total reflux, the startup time of the CO cryogenic distillation column are 23 to 30 days with the ¹³C concentration up to 15%, and the setup has the capacity of producing 500 g 10% ¹³C per year. The developed corrugated gauze packing with high specific surface area has better separation ability than the traditional packing with the separation work and the theoretical plates per unit specific surface area being two times higher than those of foreign facilities.4.On the basis of steady and dynamic simulations about the cryogenic distillation system with three isotopic components ¹²C¹⁶O-¹³C¹⁶O-¹²C¹⁸O, the influence factors of ¹³C isotope separation were studied. The single factor analysis by steady-state simulation showed that the product abundance improved with the decreasing of pressure, the increasing of reflux ratio, and the reducing of gas kinetic energy factor. By experimental uniform design, the optimized condition to the established column for the re-boiling power of 250 W was that the operating pressure was 54 kPa and the reflux ratio was 84. Low pressure, high reflux ratio is helpful for reducing this experimental column’s energy consumption. Through the dynamic simulation, it was found that with the increasing of feed rate and re-boiling, the balance time of enrichment was shorter.5. 3-D physical models were established for the corrugated packing applied in the experiments. Through the CFD simulations, it is shown that in the process of distillation with countercurrent flow, the surfaces of traditional corrugated packing were not moistened by liquid due to the structural defect, and most of the liquid flow as streams in the packing channels. Liquid misdistribution is probably caused by the packing structure, irrespective with the packing height. Through the CFD simulations, the existence of entrainment phenomenon was also proven. The concept of mass transfer liquid flooding point based on liquid holup was proposed in this study, which was better to define the effective mass transfer ranges of structured packing with high specific surface areas. The newly proposed zigzag corrugated packing has right-triangle channels in structure, resulting in more superior performances in liquid distribution and higher wetting surface areas than the traditional corrugated packing. With the advantages of high mass transfer efficiency, the zigzag-pak may be widely used in conventional chemical columns to replace the traditional corrugated packing.更多还原