Computer-Aided Simulation Procedure for Water Distillation Columns

A computer-aided simulation procedure is proposed for a water distillation column which has hundreds of stages. The procedure allows us to simulate a column processing all the six molecular species H₂O, HDO, HTO, D₂O, DTO and T₂O. By using the approximation that the isotopie exchange reactions are equilibrated in liquid phase and linearizing the atom balances for two of the three elements (H, D and T) around each stage, the Newton-Raphson iteration is applied to the main calculational loop. As a consequence, the Jacobian matrix has a block tridiagonal form and the order of the arrays is just two even in cases of the six component system. Thus, the serious problem of huge computer storage requirements inherent in previously reported procedures using the Newton-Raphson method is completely eliminated in the present procedure.

The procedure is very useful to the solution of operating problems for water distillation columns used as the upgrader of heavy water from the heavy water reactor and the finisher in the heavy water production process.     

氢-水同位素催化交换速率及过程模拟的研究进展

氢-水同位素催化交换在处理ITER聚变堆废水以及核裂变反应堆重水升级方面具有应用前景。该交换过程及核心设备催化交换塔的模型化研究,对工艺和工程优化设计具有十分重要的意义。本文重点介绍了氢-水同位素催化交换过程模拟的研究进展,讨论了同位素催化交换速率的计算方式以及吸收塔模型和滴流床模型在同位素催化交换过程模拟中的应用,探讨了氢-水同位素催化交换过程模拟今后的研究方向。通过各类模型的比较,滴流床模型被认为在催化交换过程模拟中有良好应用前景。氢-水同位素催化交换机理及速率计算方法和催化交换塔模型化等方面有待进一步研究。     

Pt/C对氢同位素交换反应的催化性能研究

采用并流法研究了用不同活性炭担体制备的Pt/C对H2（g）/HDO（v）体系的催化性能,得出Pt/C对氢-水同位素交换反应的活化能为41.3～42.4kJ•mol－1。实验结果表明,采用表面改性活性炭制备的Pt/C对H2（g）/HDO（v）的催化活性比未经改性活性炭制备的Pt/C高出1倍,但两者对水蒸气均为0.77±0.05级反应,其活化能也基本相等,说明活性炭担体表面改性未改变Pt/C对氢-水同位素交换的反应机理。     

Ni基催化剂的氢-水汽相催化交换性能

汽相催化交换(VPCE)是水除氚的重要手段之一,本研究采用金属Ni替代常用的贵金属Pt作为逆流型VPCE工艺的催化剂,研究了其在多种实验条件下HDO-H2反应体系中的静态及动态催化交换性能。实验结果表明:静态实验时,催化剂在温度大于200℃、压力和反应物浓度的摩尔比值(HDO∶H2)越大的条件下,催化交换反应向正方向移动,催化性能更好;在Ni高负载率的情况下,其催化性能优于Pt基催化剂。动态实验时,产物平衡氘浓度与静态实验一致,H2中氘摩尔浓度均为1%左右;且进料比例对结果的影响规律与静态实验一致,反应物HDO越多,产物氘浓度越大。本研究表明了纯Ni催化剂在HDO-H2催化交换反应体系中有着较为明显的催化作用,可以替代传统贵金属Pt作为逆流型VPCE工艺的催化剂。     

Numerical Analysis on Heavy Water Separation Characteristics for Pair of Bithermal Trickle-Bed Type H2/H2O-Exchange Columns

In order to study how the operating pressure and temperature have influence on the heavy water separation characteristics for a pair of bithermal trickle-bed type H₂/H₂O-exchange columns packed with the hydrophobic Pt catalyst, the authors utilized the analytical expressions derived from the differential equations expressing the material balance of the three components, hydrogen, water vapor and water in the exchange column.

The cases where the operating temperature in a hot column is 200°C, the deuterium enrichment factor is 3, the hydrogen superficial velocity is (0.2)×(Operating pressure (atm)) (Nm/s) and the column efficiency is high and low were studied. As the results, the optimum operating pressure is about 50 atm in both cold and hot column, the optimum operating temperature in a cold column is 100°C and other important parameters such as the optimum length of a cold and a hot column, the optimum hydrogen to feed water molar flow ratio and the optimum degradation ratio were also obtained.     

水-氢交换氢同位素体系HD/H_2O、DT/D_2O和HT/H_2O分离性能模拟研究

计算模拟应用于氢同位素分离领域,能够方便、快捷地进行工艺条件分析。本工作采用数值模拟的方法对比研究了水-氢催化交换过程中HD/H_2O、DT/D2O和HT/H_2O三种氢同位素体系的分离性能。研究表明:在一定工艺条件下,三种体系均在操作温度为343K时达到最大的分离效果;随着气液比从1.0增大到3.0,最优操作温度均从343K降低到323K,但是在此过程中,HT/H_2O体系的分离效果受温度的影响较小一些;在达到最大分离效果的目标下,HT/H_2O体系需要的理论塔板数比HD/H_2O和DT/D2O体系少,同时,在优化的工艺条件下,三体系气相中氢同位素浓度在交换柱内分布曲线存在一定的差异。