Parametric sensitivity and runaway in chemical reactors

In certain regions of operating conditions, chemical reactors may exhibit parametric sensitivity; i.e., small changes in one or more of the reactor input parameters lead to much larger changes in the output variables. Since such behaviour leads to deleterious performance, it is of practical interest to identify regions of parametric sensitivity in the reactor parameter space. Until recently, this could be done only to describe thermal runaway, and only for those systems where a temperature profile could be defined. Both of these limitations can be removed by consideringthe generalized criterion for parametric sensitivity, whereby sensitivity ofany output of the model toany input can be treated. Applications of the generalized criterion are discussed, with specific examples including pseudohomogeneous and heterogeneous model tubular reactors, a nonisothermal CSTR, and a polymerization reactor. Dedicated to Dr L K Doraiswamy — Gentleman, Scholar, Friend — on his sixtieth birthday.     

论解决核电安全问题的途径

从现有水冷反应堆核电厂存在堆芯熔化危险这一安全问题的焦点出发,分析了改进型反应堆AP-600、SIR、非能动安全反应堆PIUS和具有固有安全的模块高温气冷堆MHTGR等的安全特性.按照下一代水冷反应堆的设计要求和用户要求,提出了解决水堆核电厂安全问题的新概念——自安全铀氢锆反应堆,该堆型可能成为世界水堆核电发展的一个方问。中国核动力研究设计院正在探讨这种堆型。     

Modeling strategies for unsteady turbulent flows in the lower plenum of the VHTR

Validation simulations are presented for turbulent flow in a staggered tube bank, geometry similar to the lower plenum of a gas-cooled high temperature reactor. Steady 2D RANS results are compared to unsteady 2D RANS results and experiment. The unsteady calculations account for the fact that nonturbulent fluctuations (due to vortex-shedding) are present in the flow. The unsteady computations are shown to predict the mean variables and the total shear stress quite well. Previous workers’ results indicate that 3D simulations are needed to obtain reasonable agreement; present results indicate 2D is sufficient. Best practices are based on requirements for the ASME Journal of Fluids Engineering.     

催化剂润湿对滴流床性能的影响

讨论了不同操作条件对催化剂润湿的影响,证实了用惰性细粒稀释床层能改进催化剂的润湿,研究表明,一些操作参数如压力、气体质量、流速等对接触效率有显著影响.本文报道了这些有关的实验结果.     

5MW低温供热反应堆微沸腾运行启动可行性研究

文章用RETRAN-02程序,对清华大学核能技术研究所设计和建造的5MW低温供热堆的微沸运行启动方式进行了较为系统的研究;分析了控制反应性引入速率、主回路蒸汽冷凝量大小及主回路对外总传热量的大小对启动稳定性的影响。结果表明,在一种新颖的启动方式下,只要对反应堆的某些特定参数作适当的实时控制,反应堆就能从单相向两相微沸运行方式稳定过渡。     

Design stage optimization of an industrial low-density polyethylene tubular reactor for multiple objectives using NSGA-II and its jumping gene adaptations

Design stage optimization of an industrial low-density polyethylene (LDPE) tubular reactor is carried out for two simultaneous objectives: maximization of monomer conversion and minimization of normalized side products (methyl, vinyl, and vinylidene groups), both at the reactor end, with end-point constraint on number-average molecular weight (M_n,f) in the product. An inequality constraint is also imposed on reactor temperature to avoid run-away condition in the tubular reactor. The binary-coded elitist non-dominated sorting genetic algorithm (NSGA-II) and its jumping gene (JG) adaptations are used to solve the optimization problem. Both the equality and inequality constraints are handled by penalty functions. Only sub-optimal solutions are obtained when the equality end-point constraint on M_n,f is imposed. But, correct global optimal solutions can be assembled from among the Pareto-optimal sets of several problems involving a softer constraint on M_n,f. A systematic approach of constrained-dominance principle for handling constraints is applied for the first time in the binary-coded NSGA-II-aJG and NSGA-II-JG, and its performance is compared to the penalty function approach. A three-objective optimization problem with the compression power (associated with the compression cost) as the third objective along with the aforementioned two objectives, is also studied. The results of three-objective optimization are compared with two different combinations of two-objective problems.     

钯膜反应器中乙苯脱氢反应的研究Ⅰ.实验研究

在乙苯脱氢反应中利用钯膜反应器对氢的渗透作用使反应生成的氢不断从反应区移出，提高了乙苯脱氢转化率和苯乙烯生成选择性。在分离侧吹扫气中混入氧气，可以达到反应与分离、脱氢反应的吸热与氢的氧化反应放热的耦合，有利于使转化率和选择性的提高和能量的合理利用。对膜反应器的反应性能进行了研究。     

工程设计与技术进步

阐述工程设计与技术进步的密切关系以及它在基本建设中的“龙头”作用；指出工程设计是科技成果转化为生产力的重要环节。对于缺乏必要的工业试验和工程研究的一些科技成果来说，设计者的参与就是继续完成技术开发的任务。设计单位由于专业齐全、资料充实和工程实践经验丰富，能够在技术经济评价中提出中肯的意见。工程公司拥有工程设计软件品种和数量的多少、对软件的掌握程度以及活跃的二次开发能力和创新能力是衡量该公司技术水平及能否持续进步的主要标志。     

A Lumping Kinetic Model for Catalytic Reforming

ＡＬｕｍｐｉｎｇＫｉｎｅｔｉｃＭｏｄｅｌｆｏｒＣａｔａｌｙｔｉｃＲｅｆｏｒｍｉｎｇＣｈｅｎｇＧｕｏｘｉａｎｇ，ＴａｎＨａｎｓｈｅｎ，ＨｏｎｇＥｎｓｈａｎ（ＦｕｓｈｕｎＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＰｅｔｒｏｌｅｕｍａｎｄＰｅｔｒｏｃｈｅｍｉｃ...