夹套反应釜失稳爆裂原因

湖北仙桃市某乡镇制药厂,一台制药用蒸汽夹套反应釜在运行中发生失稳爆炸,调查分析发现,造成该事故的主要原因为：反应釜设计不合理及工人操作不当,压力容器管理不严所致。     

Estimating spectral properties of the thermal instability in packed-bed reactors

In response to transient perturbations, the packed-bed reactor (PBR) can exhibit dynamic thermal instability in the form of resonant amplification of process disturbances. Based on linearized PBR model we derive estimates of the resonance frequency, the frequency range where amplification takes place and the maximum amplification. We also discuss the velocity of perturbation waves and how nonlinearity of reactor response to finite-size perturbations limits the amplification predicted by the linear analysis.     

低pH对高负荷厌氧氨氧化反应器性能的影响

厌氧氨氧化(ANAMMOX)工艺是一种新型生物脱氮工艺,具有良好的应用前景。但ANAMMOX以亚硝酸盐为电子受体,需与短程硝化(SHARON)联合应用。SHARON是一个产酸反应,而ANAMMOX是一个嗜碱反应,后者会受前者的干扰。试验结果表明,低进水pH冲击对高负荷(总氮负荷9.3～27.7kg·(m3·d)-1)ANAMMOX反应器效能具有显著影响。在一定范围内,提高总氮负荷可削弱低进水pH冲击的影响,设置回流也可缓解低进水pH冲击所致的负面效应。低进水pH冲击对厌氧氨氧化反应器效能的影响主要来自低pH与游离亚硝酸毒性的双重抑制,其中低pH的直接作用对反应器效能的影响更大。低进水pH冲击所致的反应器效能恶化可采用停车自然恢复、清水冲洗恢复和外加碱液恢复。     

Wave phenomena in the packed-bed reactor: Their relation to the differential-flow instability

The steady state of a non-isothermal packed-bed reactor (PBR) is convectively unstable in the sense that upstream perturbations are amplified in the course of their downstream propagation before they are washed out by the flow. The differential-flow instability (DIFI) that underlies this dynamics arises from the different rates of transport of heat and matter in the PBR and from the autocatalytic nature of the reaction heat. In the PBR with recycle, the DIFI has an absolute character and it results in self-sustained, periodic wave activity. The DIFI-concept provides a theoretical framework for interpreting and analysing several types of wave phenomena in PBRs.     

On the dynamical instability of packed-bed reactors in the presence of catalyst deactivation

Due to the thermal instability of the packed-bed reactor running an exothermic reaction, unsteady-state operation (for example a fluctuating inflow temperature) can result in a variety of thermal responses. These include the amplification of input temperature perturbations and high-temperature pre-extinction waves. Catalyst deactivation adds further dynamical features to these scenarios. We explore them numerically, using a first-order exothermic reaction and a pseudo-homogeneous (single phase) model of the PBR together with a first-order deactivation model of the catalyst. At low deactivation rate, moving hot spots are found, as well as a non-uniform activity profile of the catalyst. At high deactivation rate, however, high-temperature waves (so-called pre-extinction waves) are followed by the complete extinction of the reactor. The amplification of input temperature perturbations is generally enhanced by the presence of catalyst deactivation. Finally, a power-law model is derived numerically that predicts the resonance frequency for amplification as a function of operating parameters.     

预缩聚反应器气相管“鼓泡”的成因探讨

笔者对仪化聚酯生产中预缩聚反应器气相出口管出现"鼓泡"现象进行了分析和探讨,通过定量分析探讨这一现象的成因,确定了科学合理的处理措施,解决了问题,为聚酯检修中类似情况提供有益的参考。     

Temperature excursions in packed bed reactors with an axial variation of catalyst activity

Research appears to be growing on a type of structured reactor in which catalyst activity varies or in which different catalysts are arranged in the reactant flow direction. These reactors offer improved selectivity for some classes of complex reactions under non-isothermal conditions or when composition modulation is employed. Our examination of the rather extreme case of alternating layers of inert and active catalyst indicate that this reactor structure accentuates wrong-way temperature excursions after a step-change in temperature and amplifies periodic input temperature disturbances. Experiments used a near adiabatic 2.5 cm diameter reactor packed with 3 mm particles of 0.2 wt.% Pt/Al₂O₃. Inert layers were just the 3 mm alumina particles. Step and triangular wave inputs of constant amplitude were used. Temperature response in the bed was measured by an axial array of computer-monitored thermocouples. Measurements were compared to those made on a homogeneous mixture of catalyst and support under identical input conditions. Simulation studies show that accentuation of the temperature excursions depends on layer thickness. Even first-order reaction kinetics show accentuated temperature excursions when layered beds are used.     

Fischer–Tropsch synthesis: Overview of reactor development and future potentialities

An overview of the reactors utilized for the Fischer–Tropsch synthesis is considered during three time periods: discovery to 1945, 1945–1970, and 1970 to date. A brief outline of the scientific and engineering developments related to chemical reactor design for the same three periods is also presented. In general, the reactor developments outpaced the ability to utilize the scientific and engineering advances on the academic level. However, today it appears that the academic and industrial developments closely match each other in content and interests. Even so, the availability of reliable data from large-scale pilot plants and/or commercial operations remain available only to the organization developing the data.     

新型化学反应器研究的前沿课题

对目前国内外新型化学反应器研究的前沿课题进行了简要总结，指出了开发新型与多功能化学反应器的４条途径，并给出了具体实例。     

我国烷氧基化装置的工艺进展和评述（续完）

正2.1.5第5代反应器第5代反应器是PREESS喷雾反应器和BUSS文丘里混合反应器的组合,是组合式烷氧基化反应器(见图8)。第5代工艺中也有单循环回路和双循环回路2种工艺,根据产品品种的不同而采用不同的工艺。在联泓集团昊达化学有限公司工程中,生产低增长比的产品时采用无小循环回路的单回路循环工艺,生产高增长比的产品时采用双回路循环工艺。     

环路反应器工程研究

在冷态模型装置上了环路反应器的流体力学特性和化学反应特性,建立了喷嘴喉部两相流的速度与喷嘴结构和操作压力的函数。在流体力学中得到的最佳结构可用于反应器的优化设计,与搅拌反应釜的对比试验表明：环咱反应器的宏观化学速率优于搅拌反应器。     

滴流床反应器流体力学的研究进展

系统综述了滴流床反应器的流体力学研究现状，分析了流型的转变、床层压降和持液量的关联结果，总结了主要的反应器模型和压力对床层压降及持液量的影响，并详细讨论了操作方式对滴流床反应器流体力学的影响。     

Mathematical analysis of the performance of a packed-bed coimmobilized bioreactor

A model has been developed to describe the performance of a packed-bed coimmobilized biochemical reactor. Each step in the consecutive reaction is assumed to follow Michaelis—Menten type kinetics. The model includes all the limiting steps controlling the rate of reaction and the additional effect of axial dispersion of bulk liquid. The model equations are solved by the explicit finite difference method from the transient to steady-state condition. The effects of various parameters of physical importance on the reactor performance are discussed.     

Target bounds on reaction selectivity via Feinberg's CFSTR equivalence principle

In this work, we show that the continuous flow stirred tank reactor (CFSTR) equivalence principle, developed by Feinberg and Ellison, can be used to obtain practical upper bounds on reaction selectivity for any chemistry of interest. The CFSTR equivalence principle allows one to explore the attainable reaction region by decomposing any arbitrary, steady‐state reactor‐mixer‐separator system with total reaction volume V > 0 into a new system comprising CFSTRs (where is the number of linearly independent chemical reactions) with the same total reaction volume and a perfect separator system. This work further refines the allowable selectivities by incorporating capacity constraints into the CFSTR equivalence principle to prevent arbitrarily large recycle streams between the CFSTRs and the separators and infinitesimally small CFSTR conversions. These constraints provide practical upper bounds on reaction selectivities of chemistries completely independent of reactor design. We present the methodology and the results for a selection of realistic chemistries. © 2017 American Institute of Chemical Engineers AIChE J, 64: 926–939, 2018     

Comparison of two-phase and three-phase methanol synthesis processes

A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The basic kinetic and thermodynamic data were taken from previous studies carried out in our laboratory. The results show that both reactor systems produce comparable methanol yields under the same process conditions except for the reactor temperature. Carbon conversion to methanol values close to 100% can be achieved. The three-phase process is more efficient in terms of heat recovery and power consumption. This is primarily caused by the fact that the three-phase process generates high-pressure steam and the ICI two-phase process yields boiler feed water of 90°C. Furthermore, the pressure drop in the three-phase reactor is smaller than in the two-phase reactor, resulting in a smaller duty of the recycle compressor. However, for the present low energy prices, the annual financial savings, coupled with these energetic aspects, are not sufficient to compensate for the higher capital investment of the three-phase reactor system relative to the ICI two-phase reactor system. A relatively high natural gas price of US $4.1 per gigajoule is needed to reach the economical break-even point between the two processes. More active catalysts may be developed in the near future. Our results show that a relative increase in the catalyst activity by a factor of 1.5 or more (for both processes) will make the three-phase process of economic interest at a natural gas price of US $2.5 per gigajoule.     

乙氧基化反应器的模型化及其研究进展

介绍了乙氧基化原理及工业反应器的特征,综述了乙氧基化反应器的模型化方法,包括动力学、气液平衡、质量传递模型及参数获取方法。介绍了工业半间歇乙氧基化反应器的模拟方法及取得的一些进展,并对该领域的研究提出展望。     

SBR工艺的现状与发展

序批式间歇活性污泥法(SBR)是近年来应用日趋广泛的一种污水处理工艺,在SBR工艺的基础上,又发展了一些SBR的变型工艺,例如ICEAS工艺、CASS工艺、UNITANK工艺、ASBR工艺、BSBR工艺等。今后应加强SBR工艺中微生物的研究和可靠的工程设计模式的探讨。     

反应器若干操作优化问题

分别对间歇操作反应器的最佳反应时间和连续操作反应器及其最佳进料方式进行分析，对实际生产有一定的指导意义。     

大型冷模研究初探

从研究大型冷模试验的必要性出发，介绍了大型冷模试验的理论依据，探讨了工业上常用的固定床反应器、流化床反应器以及当前重点研究的三相鼓泡淤浆床反应器的大型冷模试验的基本内容，为从事这一领域的研究人员提供了基本知识。     

Modeling of solid-state polycondensation. II. Reactor design issues

The relative merits of the moving packed bed, fluidized bed, and stirred bed reactors for solid-state polycondensation are discussed along with methods for improving these designs. A general model to describe continuous solid-state polymerization reactors is then developed and illustrated by a case study of a moving packed bed reactor showing the relative importance of operating variables. The model also predicts the dynamic behavior in response to several process inputs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1775–1788, 1998