生物柴油制备过程中反应器的研究进展

叙述了管式和滴流床等传统反应器和膜反应器、微通道反应器、反应蒸馏反应器等新型反应器在生物柴油制备的应用和发展,并对反应器的应用前景做了评述和展望。认为改进的传统反应器和新型反应器在生物柴油生产中都有一定的发展前景。新型反应器仍需要解决一些基本的过程问题,如微通道反应器的平行放大控制、腐蚀,膜反应器的选择性．反应蒸馏反应器的模型放大优化问题。     

化工反应器的开发

本文阐述了常见的釜式反应器以及固定床反应器与分离式反应器等反应器的基本原理、设计步骤及影响因素,并对其优缺点进行了比较,考虑到了反应器设计中应该注意的问题,并对反应器的设计前景提出了展望．     

大规模植物细胞培养生物反应器

讨论了植物细胞大规模培养的基本特性。根据分析比较了在植物细胞悬浮培养中通常使用的几种生物反应器,包括摇瓶,搅拌式反应器,气升式反应器,转瓶反应器以及带挡板的转瓶反应器,指出综合性能以气升式为最佳。此外还介绍了固定化植物细胞反应器以及生物膜反应器,讨论了大规模植物细胞培养反应器的选择原则。     

微反应器技术在精细化工中的应用

近年来,微反应器技术已逐渐成为国际精细化工技术领域的研究热点。该文介绍了微反应器技术的最新研究进展;通过分析微反应器的内在结构特征,阐明了微反应器技术的特殊优势;分析了微反应器适合的化学反应类型;列举了大量微反应器技术应用的成功范例;通过微反应器技术和常规反应器技术的比较,说明了微反应器技术在精细化工领域的巨大价值和动人前景。     

微反应器研究及展望

综合概括了微反应器(微通道反应器)的基本概念,把微反应器与其他微通道设备相区别;从化学反应工程的角度按气固相催化微反应器、液液相微反应器、气液相微反应器和气液固三相催化微反应器等类型对各种新型微反应器予以简略而突出的介绍;从其几何特性出发系统而深入地阐述了微反应器具有的一系列超越传统反应器的独特优越性;简略介绍了微反应器的制作、研究现状和展望。     

乙氧基化管式反应器的数学模拟

建立了乙氧基化管式反应器的数学模型,考察了各参数对反应器温度分布的影响,认为反应器具有较强的参数敏感性,冷却剂进口温度是影响反应器温度分布的主导因素。分析了反应器的参数敏感性,得到了反应器的安全操作区域,对放大和生产操作提供了理论指导。     

新型膜生物反应器及膜污染的研究进展

膜生物反应器技术是近年新发展起来的污水处理技术.作者介绍了几种新型膜生物反应器(生物膜-膜生物反应器、动态膜-生物反应器、气升循环膜生物反应器、PAC-膜生物反应器)的发展状况,并对膜生物反应器的膜污染机理及其控制方法进行了探讨,对今后膜生物反应器的研究和发展进行了展望.     

天然气制氢反应器的研究进展

氢是一种理想的能源,高纯氢的制备是近年研究的一个重点,反应器的结构是制氢的关键。本文综述了固定床、流化床、膜反应器、等离子体反应器、太阳能反应器和微通道反应器在甲烷制氢研究中的应用,分析了各种反应器在制氢过程的特点以及不足之处,指出了制氢反应器的发展方向。     

生物柴油新反应器及其应用

生物柴油是石化柴油的重要补充.用传统的搅拌釜和管式反应器制备生物柴油,存在反应速率慢、转化率低的问题.从提高反应速率和转化率两方面综述了生物柴油新反应器的研究进展.提高反应速率的反应器包括:微波反应器、空化反应器、旋转床反应器、振荡流反应器、高剪切反应器、静态反应器、微反应器和液液膜反应器.提高转化率的反应器包括:反应/分离器、反应蒸馏反应器和膜反应器.比较了它们的优势和缺陷.提出联合使用几种技术,将强化传质与分离技术进行有效整合,使反应器小型化并缩短工艺流程,以建立适应未来的生产效率高的便携式生物柴油厂.     

碳热还原法合成AIN粉末的径向反应器设计

本文将传质原理与化学反应动力学相结合,导出了氮气流量与碳热还原法合成AIN反应速率之间的关系。基于动量守恒定律分析了径向反应器内部气体压力及其分布的规律,提出了气体在反应器内均匀分布的条件和反应器选型准则。根据这些条件和准则设计了合成AIN粉末的径向反应器。实验结果显示AIN的转化率及颗粒度在径向反应器内均匀分布,且产率高于平底状反应器。这一结果证明反应器设计合理,径向反应器比平底状反应器有更好的传质效果。     

气升式环流反应器研究与应用进展

综述了气升式反应器性能的主要影响因素研究及其最新的应用，提出今后研究工作的主攻方向，并介绍了最近超声气升式反应器及光气升式反应器的研究结果。     

HYDRODYNAMIC STUDIES ON LOOP REACTORS(Ⅱ) AIRLIFT LOOP REACTORS

Hydrodynamics of airlift loop reactors was studied in detail experimentally andtheoretically.An internal airlift loop reactor was designed and set up for this study.An instru-mentation system based on the electrochemical method was adapted to measure local gas holdup andliquid velocity.A two-dimensional two-fluid model based on the first principles was established andimplemented to model the flow in airlift loop reactors.A corrected turbulent model was incorporatedin the simulation.The shear rate,shear stress and energy dissipation are evaluated from the flowfield.The numerically predicted results and experimental data obtained from this work as well as thesereported in literature are analyzed and compared.     

Effect of Surface Tension on Hydrodynamics and Mass Transfer Coefficient in Airlift Reactors

The hydrodynamics and volumetric mass transfer coefficient play important roles in the design and scale-up of airlift reactors. The effect of surface tension on hydrodynamics and volumetric mass transfer coefficient in internal loop airlift reactors was investigated. With reduction of the surface tension of the fluid, the hydrodynamic parameters raised, namely, gas phase holdup, flow regime transition point, and interfacial area, whereas the bubble diameter as well as the liquid velocity decreased and the volumetric mass transfer coefficient increased. Empirical correlations are proposed for gas-phase holdup and volumetric mass transfer coefficient in terms of dimensionless numbers and can be applied in the design of airlift reactors.     

Hydrodynamic Modelling of Internal Loop Airlift Reactor Applying Drift‐Flux Model in Bubbly Flow Regime

A new model for the liquid circulation rates in airlift reactor (ALR) is presented. The model is based on the energy balance for the flow loop (riser, turn riser‐downcomer, downcomer, and turn downcomer‐riser) coupled with a drift flux theory of two‐phase flow gas‐liquid system, considering a bubbly flow regime. The predicted values of the liquid circulation rates by the developed model are compared with experimental results performed in a 22 dm³ internal loop airlift reactor and with the results obtained in the literatures. The proposed model predicted the experimental results very well. Slip velocity relationship based on the drift flux model was proposed; including the gas holdup, bubble size and the liquid physical properties. The predicted slip velocity was similar to that obtained from the literature. The study revealed that appropriate arrangements of internal bioreactor parts can positively influence the liquid circulation velocity at the same energy consumption. The proposed models are useful in the design; scale up and characterization of the internal loop airlift reactors, and provides a direct method of predicting hydrodynamic behaviour in gas‐liquid airlift reactors.     

ESTIMATION OF EFFECTIVE SHEAR RATE FOR AERATED NON-NEWTONIAN LIQUIDS IN AIRLIFT BIOREACTOR”“

Effective shear rate is one of the indispensable parameters for the design of aerobic fermentors using a viscous non-Newtonian system. The estimation of effective shear rate in airlift loop bioreactors has been investigated with liquid circulation velocity. An empirical correlation of effective shear rate in airlift loop reactors is proposed.

γ_eπ= 3.26-3.51 ; 10²U_G + 1.48 10⁴U²_G

It is found that the effective shear rate is lower in airlift reactors than in bubble columns. This equation can be used for the cultivation of cells sensitive to shear stress.     

气升式环流反应器内传质行为的分析与测量

1 INTRODUCTION Airlift loop reactors have emerged as one of the most promising devices in chemical, biochemical and environmental engineering operations. Its main ad-vantages over conventional reactors include excellent contact among different phases, ease of removal or replenishment of particles, and high heat and mass transfer rates[1]. High gas-liquid contacting area and favorable flow pattern are the attractive features of this type of three-phase contactors. Typical processes that ca…     

有无静态混合器时的机械搅拌气升式环流反应器传递特性研究

The mechanically stirred internal loop airlift reactors equipped with or without static mixers are devised for intensification of gas-liquid mass transfer rate. The influences of superficial gas velocity, agitation or static mixers on gas hold-up, mixing time, liquid circulating velocity and volumetric mass transfer coefficient have been investigated with tap water and carboxymethyl cellulose (CMC) aqueous solution. The experimental results indicate that mechanical agitation is more efficacious than static mixer in highly viscous media for improving mass transfer in airlift reactors. The empirical correlation of volumetric mass transfer coefficient with apparent viscosity, and energy consumption for mechanical agitation and aeration is developed.     

Simulation and experimentation on the gas holdup characteristics of a novel oscillating airlift loop reactor

BACKGROUND: The classical airlift loop reactor (ALR) has been widely used in petrochemical, biochemical, energy and environmental processes due to such advantages as simple structure, without motional mechanism, easy sealing and low energy consumption. A novel ALR has been designed using forced periodic reversible ventilation, termed an airlift reversible loop reactor (ARLR). RESULTS: Using computational fluid dynamics (CFD) simulation and experimental validation, the mass transfer characteristics of the ARLR were studied. The simulation results predicted the experimental data well, especially at low ventilation capacity. The oscillation period had significant effects on gas holdup and the mass transfer coefficient of the ARLR. When ventilation capacity was increased from 0.22 to 3.49 vvm, compared with central airlift and annular airlift reactors, ARLR increased the mass transfer coefficient by 9–31% and 10–58%, respectively, according to simulation results, and by 11–25% and 14–58%, respectively, according to experimental data. CONCLUSION: The results showed that the ARLR could significantly enhance gas holdup and mass transfer coefficient compared with traditional central airlift and annular airlift reactors. Results indicated that the optimum oscillation period decreased with increase of ventilation capacity. ARLR has the potential for application in aerobic fermentation. © 2012 Society of Chemical Industry     

三相环流反应器流体力学行为

气升式三相环流反应器综合了鼓泡塔和机械搅拌釜的优良性能,具有结构简单、无机械传动部件、易密封、造价低、容易实现工业放大等优点,在石油、化工、电化学和生物化工等领域得到了广泛应用．随着能源形势的日趋紧张,环流反应器在液相法合成甲醇、浆态床一步法合成二甲醚、煤液化等过程中的应用得到许多研究人员的重视,并取得了重要的研究进展．由于目前对其内部流动行为尚缺乏系统的认识,进行工业设计和操作过程中仍显理论指导不足     

LOCAL LIQUID SIDE MASS TRANSFER MODEL IN AIRLIFT LOOP REACTOR AND SELF-ASPIRATED REVERSED FLOW JET LOOP REACTOR

Combining Higbie's penetration theory and Kolmogoroff's theory of isotropic turbulence, a small-scale isotropic mass transfer model for the local liquid side mass transfer coefficients in a gas-liquid two-phase airlift loop reactor and a self-aspirated reversed flow jet loop reactor has been developed. Good agreement with the experimental data suggests a general applicability of the proposed model in these reactors.