液固循环移动床反应-再生系统的颗粒循环量调节和输送

液固循环移动床反应－再生系统由上下两个或两个以上的反应室、再生室、连通管和颗粒提升管组成。颗粒经再生室、反应室向下移动,进入输送管后被向上输送返回至再生室。颗粒循环能力决定了反应室和再生室内的颗粒更新速率。是循环移动床操作的关键之一,对反应器的颗粒循环进行了实验研究,提出了一种射流输送和调节结构并对射流输送行为进行了模拟计算。     

新型液固循环移动床流动特性的实验研究

在新型液-固循环移动床反应-再生冷模装置中,以水-玻璃珠为液-固体系,对300 mm×3 000 mm的液-固循环移动床再生器内的操作域和流动特性进行了研究.实验结果表明,下料管出口和料位高度的相对位置对床层流动状态有较大影响,当料位高度高于下料管出口高度时,床层流动可以分为局部流化床区和移动床区两个区域.随着表观再生液速的增大,移动床区先后经历了移动床流动和散式流化床流动,移动床流动的操作液速为0～6.5 mm/s,散式流化床流动的操作液速为6.5～20.5 mm/s.随着表观再生液速的增大,移动床层各轴向高度颗粒平均速率均增大;表观再生液速超过一定值后,颗粒平均速率基本不变.在各轴向高度床层上,随着表观再生液速的增大,局部流化床区周向影响区中心夹角不断增大.     

液固环流反应器反应-再生系统结构对液固流动的影响与窜液分析

液固环流反应器以导流筒作为反应室,环隙作为再生室,从而将反应一再生系统集成于一个反应器之中,颗粒分别依靠射流卷吸力和自身重力围绕着导流筒壁上下循环。今采用互相关技术在不同的分布板环管内径、导流筒高度和直径、喷嘴内径条件下,测量了反应器内颗粒速度和浓度分布。实验结果表明,上述结构尺寸分别减小,导流筒内的颗粒速度和浓度均有所提高。但是,环隙中的颗粒流动规律并不完全与导流筒内的一致。最后,探讨了窜液量对反应再生效果的影响,推导出其理论控制模型,并进行了模拟计算。     

液固环流反应器的反应-再生系统操作分析及导流筒模拟

液固环流反应器以导流简作为反应室,环隙作为再生室,从而将反应-再生系统集成于一个反应器之中,颗粒分别依靠射流卷吸力和自身重力围绕着导流简壁上下循环。今采用互相关技术在不同的操作条件下,测量了反应器内颗粒速度和浓度分布。实验结果表明,反应液流量提供了颗粒循环的主要动力,再生液流量与其配合是实现环隙逆流的关键,松动液流量则能改善导流简内颗粒流化效果。最后,还对反应器关键部位——导流简内的颗粒输送进行了模拟,以利于将来进一步对该新型反应器的开发与设计。     

新型液固循环床提升管颗粒速度径向分布的实验研究

新型液-固循环流化床与常规液-固循环流化床的区别在于提升管底部入口结构和顶部出口结构的不同.实验装置为φ80×8000 mm有机玻璃床,新结构可在较高表观液速和较高颗粒循环速率下操作.利用光纤速度测量仪测量床内颗粒速度径向分布,得到了颗粒速度径向分布规律.通过对实验结果分析发现,新型循环流化床颗粒速度径向分布与较高的表观液速和颗粒循环速率以及由此引发的较大的边壁效应密切相关.     

喷嘴对液固外循环流化床内颗粒循环特性的影响

液固外循环流化床换热器可以用来蒸发浓缩单基药提取硝化棉的提取液.设计了实现液固外循环流化床内颗粒正常循环的关键部件喷嘴,构建了以喷嘴作颗粒循环装置的液固外循环流化床换热器,研究了喷嘴的结构参数及操作参数对起始循环流体流量、全床压降、负压和最大颗粒循环流量等的影响.结果表明,喷嘴的口径比及安装位置对提高颗粒循环效果均存在一个最佳值,为外循环流化床换热器的设计计算提供了依据.     

产品信息

汽液固三相循环流化床蒸发装置汽液固三相循环流化床蒸发装置是由河北工业大学设备设计研究所和石家庄工大化工设备有限公司共同研制开发的防、除垢强化传热的高效蒸发装置。该蒸发装置由加热室、汽液分离室、固体颗粒分离装置、循环泵等组成。在蒸发系统中加入一定量、一定尺寸的颗粒 ,颗粒被循环液体带入加热室 ,与被加热介质一起形成汽 -液 -固三相流 ,然后三相流进入颗粒分离装置 ,固体颗粒被分离进入下降管参与循环 ,分离出的汽液混合物进入汽液分离室 ,二次蒸汽从顶部排出 ,液体参与下一循环 ,蒸发至一定浓度从出料口排出产品。该装置…     

总目次

二 OO一年目　　　次作　者卷期页磷酸三间甲苯酯的碱法合成吕自红 ,　朱志庆………………………………………………………… 1 71 1高压脉冲放电脱氮技术的研究施　耀 ,　谭天恩 ,　李　松………………………………………… 1 71 5甲醇合成反应热力学分析及实验研究刁　杰 ,　王金福 ,　王志良 ,　金　涌……………………… 1 71 1 0流化床反应器气固传热面积模型燕青芝 ,　李灵芝 ,　于丰东 ,　程振民 ,　袁渭康……………… 1 71 1 6液固循环移动床反应—再生系统的颗粒循环量调节和输送　　徐　聪 ,　韩明汉 ,　王金福 ,　金　涌…………     

汽液固三相循环流化床蒸发装置

汽液固三相循环流化床蒸发装置是由河北工业大学设备设计研究所和石家庄工大化工设备有限公司共同研制开发的防、除垢强化传热的高效蒸发装置。该蒸发装置由加热室、汽液分离室、固体颗粒分离装置、循环泵等组成。在蒸发系统中加入一定量、一定尺寸的颗粒 ,颗粒被循环液体带入加热室 ,与被加热介质一起形成汽 -液 -固三相流 ,然后三相流进入颗粒分离装置 ,固体颗粒被分离进入下降管参与循环 ,分离出的汽液混合物进入汽液分离室 ,二次蒸汽从顶部排出 ,液体参与下一循环 ,蒸发至一定浓度从出料口排出产品。该装置的突出特点是 :(1)汽液固三相…     

汽液固三相循环流化床蒸发装置

汽液固三相循环流化床蒸发装置是由河北工业大学设备设计研究所和石家庄工大化工设备有限公司共同研制开发的防、除垢强化传热的高效蒸发装置。该蒸发装置由加热室、汽液分离室、固体颗粒分离装置、循环泵等组成。在蒸发系统中加入一定量、一定尺寸的颗粒 ,颗粒被循环液体带入加热室 ,与被加热介质一起形成汽 -液 -固三相流 ,然后三相流进入颗粒分离装置 ,固体颗粒被分离进入下降管参与循环 ,分离出的汽液混合物进入汽液分离室 ,二次蒸汽从顶部排出 ,液体参与下一循环 ,蒸发至一定浓度从出料口排出产品。该装置的突出特点是 :(1)汽液固三相…     

Operation characteristics of a new liquid-solid circulating moving bed reactor

The liquid-solid circulating moving bed reactor is a novel one, which consists of two or more reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through an upper conduit and to the particle transport system through a lower conduit, and then are conveyed into the upper reaction chamber through a riser. The circulating rate of particles and the flow of liquid in the two conduits are key factors to the continuous steady operation of the reactor; they can be controlled by varying operating conditions: the outlet liquid flow rate in the regeneration chamber, the outlet liquid flow rate in the reaction chamber, the inlet liquid flow rate of the reactants, and the flow rate of driving flow. A flow model has been proposed to quantify the operation characteristics of the reactor. The results predicted by the model show satisfactory agreement with the experimental data.     

OPERATION CHARACTERISTICS OF A NEW LIQUID-SOLID CIRCULATING MOVING BED REACTOR

The liquid-solid circulating moving bed reactor is a novel one, which consists of two or more reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through an upper conduit and to the particle transport system through a lower conduit, and then are conveyed into the upper reaction chamber through a riser. The circulating rate of particles and the flow of liquid in the two conduits are key factors to the continuous steady operation of the reactor; they can be controlled by varying operating conditions: the outlet liquid flow rate in the regeneration chamber, the outlet liquid flow rate in the reaction chamber, the inlet liquid flow rate of the reactants, and the flow rate of driving flow. A flow model has been proposed to quantify the operation characteristics of the reactor. The results predicted by the model show satisfactory agreement with the experimental data.     

Study on the stress distribution and modeling of the stand pipe in a circulating moving bed

The liquid-solid circulating moving bed reactor is a novel one, which consists of two reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through a coupling standpipe and to the particle transport system through a bottom standpipe, and are then conveyed into the upper reaction chamber through a riser. A stress distribution model based on the equations of continuity and momentum balance in the reactor is established and used for simulations which shows that the stress concentration regions are at the coupling standpipe and the bottom of the regeneration chamber. To reduce the largest stress in the stress concentration regions and to minimize catalyst consumption, the regeneration chamber should be designed to give a low ratio of height to diameter. Zoning diagrams of the flow patterns in the bottom standpipe are proposed and the flow patterns can be readily deduced from the pressure gradient.     

Influence of ring-type internals on the solids residence time distribution in the fuel reactor of a dual circulating fluidized bed system for chemical looping combustion

The intensification of gas-solids contact in the fuel reactor of a chemical looping combustion system is enhanced with the installation of ring-type internals. This can be a key issue for achieving the necessary fuel conversion rates. Wedged rings, previously designed and tested, were found to increase the particle concentration in the counter current section of the fuel reactor and hence, to achieve a more homogeneous particles concentration along this zone. The present work investigates the effect of the mentioned internals on the residence time distribution of particles in the fuel reactor of a dual circulating fluidized bed system for chemical looping. The study was carried out in a cold flow model especially designed for the fluid-dynamic analysis of the system equipped with a recently developed residence time measurement device based on the detection of ferromagnetic tracer particles through inductance measurement. Ring internals proved the positive effect on the particles residence time, the residence time distribution is more symmetric and shows lower dispersion, the flow pattern is more plug-flow-like, these effects are intensified with the reduction of the aperture ratio of the rings. On the other hand, the upward particle transport in the counter-current zone of the fuel reactor also increases with the installation of the rings, increasing the bypass flow of solids through the fuel reactor's return loop (internal circulation). For high internal circulation rates the solids residence time distribution of the fuel reactor is dominated by the bypass effect. The findings may be used for focused design improvement of the investigated fluidized bed system.     

耦合反应器提升管段颗粒速度分布及约束特性

A large-scale cold model experimental setup of a riser-fluidized bed coupled reactor was established according to the olefin reduction technology with an auxiliary reactor for FCC naphtha upgrading.Distributions of particle velocity in the riser section were experimentally investigated in the setup.Furthermore,the restriction index of particle velocity was defined to quantitatively show the restriction effects of the riser outlet lotus-shaped distributor and the upper fluidized bed on the particle flow behavior in the riser.The experimental results showed that the riser could be divided into two regions in the longitudinal direction,i.e.,lower traditional transport region and upper restriction region.In the longitudinal direction,the averaged cross-sectional particle velocity in the traditional transport region increased firstly,and then tended to be smooth,while decreased in the restriction region.With the increase of static bed height in the upper fluidized bed,the local particle velocity decreased,and the tendency of change in the core region is more than that in the wall region.Restriction effects of the lotus-shaped distributor and the upper fluidized bed on particle flow behavior enhanced with the increases of superficial gas velocity,solids flux and static bed height in the upper fluidized bed.In the same cross-section,outlet restriction effects enhanced with the increase of the dimensionless radial position r/R,and would not change when r/R≥0.5.     

EFFECTS OF PARTICLE CHARACTERISTICS ON THE PERFORMANCE OF A FAST FLUIDIZED BED REACTOR

A heterogeneous model for the fast fluidized bed reactor which carries out a gas-solid non catalytic reaction is presented. The hydrodynamics of the fast fluidized bed is characterized by the model of Kwauk et al. (1985) which assumes the existence of two phases; a dense phase and a dilute pneumatic transport phase. For a given solid flowrate, the length of the reactor occupied by each phase depends on gas velocity, particle diameter and density and average voidage within the reactor. The gas-solid reaction is assumed to follow the shrinking core model. The solids are assumed to be completely backmixed in the dense phase and move in plug How in the dilute pneumatic transport phase. The gas phase is assumed to be in plug flow in both phases

For given gas and solid flowrates, the transition from the dense phase flow to the fast fluidized bed (containing two regions) as functions of particle size and density is determined using the model of Kwauk et al. (1985). The numerical solution of the governing mass balance equations show that for given solid and gas flowrates, (and average voidage) the gas phase conversion shows an unusual behavior with respect to particle diameter and density. Such behavior is resulted from the effects of particle diameter and density on the reactor volume occupied by each phase and the effect of particle diameter on the apparent reaction rate. The numerical results show that a fast fluidized bed gives the best conversion at large particle density and for the particle diameter which results the fast fluidized bed to be operated near the pure dense phase flow.     

Experimental study of gas-dynamically induced nanoparticle synthesis by use of adapted sampling probes

A new process for the synthesis of nanoparticles in the gas-phase is experimentally investigated. The gas-dynamically induced nanoparticle synthesis uses the initiation of the chemical reaction by gasdynamic shock and the quenching of high temperature gas by accelerating the flow from subsonic flow speed to supersonic speed. Therefore, the design of the reactor consists of two Laval nozzles. The process provides high heating and cooling rates, an adjustable reaction time and a particle synthesis at constant thermodynamic conditions to obtain non-aggregated nanoparticles. In order to analyze the synthesized SiO₂ particles during their growth, samples are taken in the reaction volume and downstream of the quenching. The particles from the reaction chamber were extracted with the help of a specially designed water-cooled probe. The geometry of the probe is optimized by CFD simulations. The particles downstream the quenching are extracted by a heated and isolated probe. The particles are collected on TEM grids. The experimental investigations show that the synthesized particles are spherical and non-aggregated in the reaction chamber and after quenching. The possibility to synthesize a non-aggregated product in the novel process is thus demonstrated. The mean particle size is defined by the process conditions and varies from 25 to 37 nm after quenching.     

气升式环流反应器液相流场的研究

运用粒子图像测速仪(PIV)技术测量了一拟二维气升式环流反应器内液相流动状态。避开了气液两相成像带来的图像处理困难。成功测取了时均液相速度、瞬时雷诺应力、剪切应力等在反应器下降段内的分布;考察了反应器上升段进气量和反应器液位高度对液相循环速度的影响;同时,对反应器三个具有代表性的流动部分进行了观测,获得了该反应器内液相流场具有代表性意义的速度分布图。研究结果为认识该类反应器的性能及进行反应器设计、优化提供了有价值的参考信息。     

Phenomenological approach to interpret the effect of liquid flow modulation in trickle bed reactors at the particle scale

This work analyzes the influence of liquid flow modulation on the behavior of a reaction occurring in a spherical porous particle within a trickle bed reactor. A single first-order reaction between a gaseous reactant and a non-volatile liquid reactant is considered. Non-steady-state mass balances for gas and liquid reactants are formulated and solved under isothermal conditions in order to focus the analysis on the mass transport effects. Dynamic reactant profiles inside the catalytic particle are obtained for different cycling and system conditions. The enhancement factor (ε) due to periodic operation is defined to evaluate the impact of induced liquid flow modulation on reaction rate. Influence of cycling and system parameters on the enhancement factor is also reported for a wide range of conditions. Experimental trends observed by several authors can be explained with this approach.