Ne同位素分离中微量杂质的气相色谱法

用气相色谱法测定热扩散法生产的Ne同位素气体的化学纯度。Ne同位素产品中的杂质主要为O2和N2(≤0.1%)及极微量的CO2、CH4、Ar、He、H2。Ne同位素产品分析过程借助控制待测气体中关键组分O2、N2的方法可以间接表征Ne同位素气体的化学纯度。实验采用H2气为载气、分子筛为固定相、柱温40.5°C,O2、N2检测灵敏度分别为0.0113%/mm、0.0331%/mm。进样方式为活动定体积进样,样品量≤2mL,平均偏差分别为0.01%、0.03%。     

硼同位素开发进展与生产

采用化学交换法分离硼同位素,通过在三氟化硼—苯甲醚体系中进行了硼同位素分离生产性试验,使得硼-10同位素在液相富集,硼-11同位素在气相中富集,达到了硼同位素分离与生产目的.经过生产性试验表明：在三氟化硼—苯甲醚体系中通过级联装置可以实现硼同位素的分离,且操作稳定、连续、可靠,可用于工业化生产.硼同位素分离试生产获得了交换塔和络合塔正常运行参数;实现了在分解塔内将络合物成功分解的工艺技术;解决了物料精馏净化技术问题;验证了在交换塔内采用聚四氟乙烯丝网填料富集硼同位素可行性,试验了操作压力、流量等工艺参数对硼-10同位素富集的影响,研究了填料的性能,为实现工业化的投建打下了坚实的基础.     

同位素分离理论在硼同位素分离中的应用

离子交换色谱法是分离硼同位素的非常有前途的方法,然而工艺过程的影响因素较多,分离实验的工作量很大,为验证同位素分离理论在描述硼同位素分离中的有效性,并将其用于指导硼同位素分离过程,减少实验次数和不确定性,文中采用多柱串联色谱分离实验方法,研究了非稳态下硼同位素在色谱柱中的分布和Y.Fujii同位素分离理论在描述硼选择性螯合树脂分离硼同位素体系的有效性,并将其理论应用于制备工艺设计和验证实验。研究结果表明:Y.Fujii的同位素分离理论除可较好地描述该体系色谱带中同位素的分布情况,理论计算结果与实验数据吻合,制备验证实验的测定结果与理论设计吻合,Y.Fujii同位素分离理论能较好地指导硼选择性螯合树脂分离硼同位素体系的工艺过程。     

锇同位素的分离与制备

对锇同位素分离与制备进行了调研和探讨。通过电磁分离实验得到锇同位素的小样，其中^187Os同位素的收率丰度为26．5％，如扣除本底污染，^187Os收集纯度达50．1％，达到一次电磁分离的国际水平。在此基础上，进一步探讨批量生产锇同位素的几种可行性方案。     

国外稳定性同位素研究的现状

稳定性同位素是特种气体的组成部分。提取稳定性同位素一般采用热扩散法、低温精馏法和化学交换法。稳定性同位素在农业、化工、医学、仪表、计量、检测技术等领域有广泛的用途。本文列举了同位素及化合物的品种、用途、包装方式、美国售价及世界产量的估计。我国稳定性同位素开发较早,但发展不太快,希引起有关方面的重视。应充分利用国内气源,分工合作,在研究、检测和包装手段方面努力填补国内空白,以满足国民经济发展的需要。     

高纯浓缩硒同位素样品的纯化与分析

利用硒元素的易挥发性,研制了一个用于微量硒样品的蒸发提纯装置,用所建立提纯流程纯化了购买的76Se、78Se和82Se3个浓缩同位素试剂。对比样品分离前后的电感耦合等离子体质谱(ICP-MS)半定量方法测定结果,该方法能够有效地将钠、钾、铁和钨等为主的干扰元素去除,纯化后样品中硒的纯度可以达到99.99%以上,样品回收率约为90%。经多接收电感耦合等离子体质谱(MC-ICP-MS)分析样品纯化前后的硒同位素丰度,整个纯化过程没有改变硒的同位素组成。     

同位素水精馏非稳态过程制备低氘水的研究与应用

根据水精馏过程中氢、氧稳定同位素的分离特性,以及同位素精馏的稳态和非稳态级联过程的理论分析和研究,应用于水精馏法生产重氧(18O)水的分离过程,在连续生产重氧(18O)水的同时,间歇副产低氘水,使一套同位素分离装置能同时制备二种同位素产品,开发了同位素水的综合制备的技术,提高了分离装置的有效利用率.     

化学-酶法制备^15N-L-酪氨酸的研究

通过化学-酶法途径制备了稳定性同位素标记的^15N-L-酪氨酸。以大肠杆菌所含的天冬氨酸转氨酶催化自制的对羟基苯丙酮酸和^15N-L-天冬氨酸,转化成^15N-L-酪氨酸。主要对酶转化的条件进行了研究,酶反应液经分离纯化后,得到的^15N-L-酪氨酸产品的丰度达98．62％,比原料下降了0．44％,^15N的利用率达40．78％。     

高压法三聚氰胺装置OAT浓缩技术分析研究

中国石油乌鲁木齐石化分公司化工厂高压法三胺装置为欧技公司引进技术,OAT浓缩系统(OAT结晶系统和超滤系统)为第三代改良工艺,OAT浓缩工艺为新设计工艺,目前还处在试验阶段,国内同类厂都存在OAT浓缩系统频繁出现堵塞的问题,我厂对此进行了研究并处理,目前装置可长周期平稳运行.     

硼同位素分离中苯甲醚的净化工艺研究

在众多化学交换精馏法分离硼同位素的体系中,目前被用于工业化生产的是三氟化硼一苯甲醚体系,苯甲醚在分离体系中担当着相当重要的媒介作用。但在分离过程中由于各种原因苯甲醚会发生裂解,其裂解产物混入流体中必然会改变流体特性,甚至改变填料性能,降低设备效率,影响硼同位素的分离。苯甲醚的净化就成为硼同位素的分离过程中一个无法回避的问题。对苯甲醚的净化工艺进行了一些有益的探讨,并提出了部分针对性的意见。     

Ideal and Optimum Cascades

Abstract

In gaseous diffusion and gas centrifuge uranium enrichment plants, separating units are connected in cascades. The stage separation factor in gaseous diffusion is close to unity, while in a gas centrifuge it is much larger. Ideal cascades for separating binary mixtures have been designed with no mixing of the species. A new concept, particularly applicable to cascades with large stage separation factors, is called the “optimum” cascade. These cascades allow mixing, but the value of the total flow as found in some cases is less than in corresponding ideal cascades. In this paper, ideal and optimum cascades are discussed and compared.     

A Generalized Computer Model of the Transient Behavior of Multicomponent Isotope Separation Cascades

Abstract

The time dependent performance of large separation systems is a major consideration in the enrichment of the isotopes of elements that have a direct role in nuclear fuel cycles. The transient behavior of multicomponent separation cascades is described by a set of nonlinear partial differential equations that are similar in form for chemical exchange, distillation, gaseous diffusion, thermal diffusion, and other countercurrent processes. The Mound computer model is set up to solve the differential equations by a fast, implicit forward difference technique. Systems of up to 10 components can be handled with a wide variety of multiple input and output streams. With modifications, the program can be used to model systems of two or more cascades. It has been applied to the separation of the isotopes of uranium, the noble gases, carbon, oxygen, nitrogen, chlorine, sulfur and calcium. A neon isotope separation problem is given as an example of the precision with which performance can be predicted for multicomponent systems.     

Gas Separation by a Continuous Membrane Column

Abstract

The continuous membrane column provides a revolutionary new separation technique. In gaseous diffusion the continuous membrane column is used to separate as highly concentrated products both the most permeable and least permeable gases from a feed mixture of any composition. The main features of the column are countercurrent enrichment, high reflux and minimal backmixing. The new method eliminates the need for numerous interstage compressors and extensive product stream recycling found in conventional gaseous diffusion cascades.

Experiments are carried out for systems of C0₂-O₂, O₂2-N₂ (air), and CO₂-N₂ mixtures using continuous membrane columns made out of silicone rubber membrane. Also, a theoretical model is developed to interpret the experimental data. The agreement between theory and experiment is excellent. The maximum degree of separation can be achieved at total reflux. It is experimentally verified that the maximum degree of enrichment attainable by a conventional method can easily be exceeded without limit when a continuous membrane column is employed.

Finally, a comparative study has been conducted for a conventional gas permeator and a continuous membrane column.     

The Enrichment of Heavy Water in a Continuous-Type Inclined Thermal Diffusion Column

Abstract

Equations of the best angle of inclination and the maximum separation for the enrichment of heavy water in a continuous-type inclined thermal diffusion column have been derived. Considerable improvement in separation was obtained by employing the inclined column instead of using the Clusius-Dickel column.     

ENRICHMENT OF HEAVY WATER BY THERMAL DIFFUSION

Equations of the best wire angle of inclination for the maximum separation, maximum output and minimum column height for enrichment of heavy water in a concentric-tube wired thermal diffusion column have been derived. Considerable improvements in performance were obtained by employing the wired column instead of using the open column (without wire). It was also found that the wire inclination for maximum separation is also the wire inclination required to obtain the maximum production rate, or minimum column height, for a specified degree of separation.     

Enrichment of Heavy Water by Thermal Diffusion in the Frazier Schemes with Column Heights Varied at a Constant Increment for Improved Performance

The improvement of heavy water enrichment by thermal diffusion in the Frazier scheme with column heights varied at a constant increment and with the total sum of column heights fixed, has been investigated. The equations, which may be employed to predict the optimal column number and the optimal column-height increment for maximum separation, have been derived. Considerable improvement in heavy water enrichment is obtainable if the column number and column-height increment in a modified Frazier scheme with the total sum of column heights fixed, are property assigned under certain flow-rate operation, instead of using the conventional scheme of uniform column height.     

The Simplified Equation of Separation for the Enrichment of Heavy Water in a Batch-Type Thermal Diffusion Column

Abstract

A simple but precise equation of separation for the enrichment of heavy water in a batch-type thermal diffusion column has been derived with the consideration of a pseudobinary mixture. The experiment has also been conducted for various initial concentrations of D₂O and the results are in agreement with the prediction of the theory.     

Recoveries of deuterium from the separation of water–isotope mixture in batch-type thermal diffusion columns under unsteady-state operation

Heavy water (D₂O) is the most feasible moderator and coolant in nuclear-fission reactors while deuterium (D) will be the nuclear fuel for thermonuclear fusion in the distant future. The recoveries of deuterium in D₂O and HDO from the separation of water–isotope mixture (H₂O–HDO–D₂O) by thermal diffusion has been estimated. First, the degrees of separation for each component of water–isotope mixture in thermal diffusion columns were predicted, then the recoveries of deuterium in each component were estimated from the molecule weights. It was found that the maximum recovery of deuterium might be obtained when the feed concentration of D₂O is 0.22 mass fraction.     

离散流量离心分离级联的数值优化

在连续流量离心分离级联的数值优化上已有不少研究,从理论上提供了最优化的级联模型.但实际中级联各级的离心机台数必为整数,即各级流量为离散值,因此为了获取更好的分离效益,研究离散流量级联的数值优化,使其尽可能接近连续流量级联是十分必要的.论文比较了不同的优化方式,找到了简便高效地完成此种情况下数值优化的方式和策略.结果表明,离散流量和连续流量两种情况下最优级联的形状参数是完全一致的;具体的水力学参数并不相同,但相差不大.最后审视并改进了处理整实型变量混合优化的策略,减少了优化工作量,提高了优化效率.     

Separation of Heavy Water by Vapor-Phase Thermal Diffusion Coupled with Distillation and Condensation

Abstract

A study on the enrichment of heavy water in a vapor-phase thermal-diffusion column has been conducted. With the combination of the effects of distillation, vapor-phase thermal diffusion, and partial condensation, considerable improvement in the degree of enrichment has been achieved in a vapor-phase column rather than in a liquid-phase column. It was also found that even the part of enrichment contributed only by vapor-phase thermal-diffusion effect is much higher than that obtained by liquid-phase thermal diffusion.