三相内循环流化床的流体力学研究

以活性碳、陶瓷颗粒、小米为固体粒子,采用体积膨胀法测定气含率,分别考察了气体速度、固含率、粒子种类三个因素对气含率的影响.结果表明:气含率随着气体速度和固含率的增大而增大,但却不能无限的增大.选用小米做固体粒子时在相同气速下的气含率最大.     

气固脉冲流化床的流体力学特性

在直径７０ｍｍ的流化床中,采用ＦＣＣ、空心玻璃珠、细沙等Ａ类和Ｂ类颗粒,在０￣１０Ｈｚ的频率范围内,测定了气固脉冲流化床的流体力学特性。采用时间继电器改变脉冲气流的频率和脉宽周期比,利用微压传感器记录床层压力变化,研究了瞬时床层压力、平均床层压力,最大床层压降、起始流化速度、床层高度等随操作条件的变化规律,并对脉冲流化床中的气泡现象进行了初步的观察和研究,发现在脉冲流化床中气泡的形成和发展受到了有     

三相流化床反应器流体力学研究

论述了诸因素对固含率、床层压降及起始流化速度的影响,并用多元逐步线性回归法关联了各影响因素之间的关系。实验结果可为三相床反应器的开发提供研究依据。     

三相携带床的流体力学特性研究

研究了空气一水-黄沙三相系统在携带床反应器中的流体力学特性。反应器直径0．07m。实验考察了表观气速Ug、表观浆液流速UsL、固含率εs等因素对气含率εg和床层压降△P的影响以及三相携带床的操作特性。回归实验数据得到气含率及床层压降与各因素的关联式为εg=0.4084U△P=5783．672U研究结果为三相携带床工业反应器提供了流体力学依据。     

气固脉冲流化床流体力学特性的研究

在φ７０ｍｍ的流化床内，采用聚氯乙烯、玻璃珠和不规则天然刚玉等Ｂ类、Ｄ类颗粒，测定了０￣５．０Ｈｚ脉冲频率下气固流化床的基本流体力学特性，探讨了影响床层流化特性的一些主要因素，并根据实验数据对脉冲流化床的临界流化速度和临界流化压降的无因次准数式进行了关联。     

FCC细颗粒湍流流化床流体力学性能研究

ＦＣＣ细颗粒湍流流化床流体力学性能研究李俊，张蕴璧，闫遂宁（西安石油学院，西安７１００６１）（西北大学）（洛阳石化公司）关键词：流化床，湍流，气泡，空隙率１前言湍流流化床有着广泛的工业背景。湍流流化床反应器存在着物质空间分布的不均匀现象，这种分布对湍...     

三相流化床脱胶工艺及其固体颗粒的流体力学行为

在内径80mm,高1000mm的三相流态化反应器中进行脱胶试验,得到适宜的脱胶状态。分析此状态下双组分固体颗粒的碰撞压力分布规律及对脱胶效果的影响,为实现该技术的产业化提供有益的参考。     

三相流化床动力学特征的影响因素

利用电导探头测试技术,以不同粒径的玻璃珠颗粒、金精矿、金矿氰化尾渣为固相,空气为气相,不同粘度的液体为液相,对三相流化床中不同测孔的电导率进行测试和计算,系统研究了颗粒粒径(dp)、密度(r)、质量(q)、表观气速(Ug)、液体粘度(ml)等对相含率的影响. 结果表明,dp从0.05 mm增加到0.15 mm,气含率(eg)增加2%~3%,而固含率(es)减小2%~4%;其他条件相同,密度大的颗粒es和eg较小;随q增加,eg降低,es增加,玻璃珠颗粒每增加100 g,eg减小约2.5%,es增加约1.5%;随Ug增大或减小,eg和es亦随之增大或减小;随ml增大或减小,eg和es亦呈增大或减小趋势.     

气液固三相流化床中局部相含率的随机分析

本文利用Markov过程原理获得了描述三相流化床中局部相含率的随机模型,并进行了实验验证,发现拟合很好.     

单组分颗粒振动流化床的流体力学研究（1）——起始流化时床层压降

国内外振动流化床流体力学的研究由于实验条件的限制，其结果尚存在着分歧，在此情况下，本文在内径为１４８ｍｍ的振动流化床下，研究Ｇｅｌｄａｒ‘ｓＡ，Ｂ，Ｃ类物料起始流化时的床层压降，分别研究了颗粒物性与振动特性对床压降的影响，并且根据上述因素的影响，关联了起始流化时床层压降的计算式，并与画外学者的关联式进行了比较。     

Two-area model for bubble distribution in a turbulent fluidized bed of fine particles

The flow behavior of gas and solid was investigated in FCC simulator of φ710×4000/φ870×11000mm.The axial and radial distributions were detected with matrix fiber-opticprobes.It was found that the distribution of bubble diameter in the turbulent region of the fluidizedbed of fine particles was different from the results reported for lab-scale experiments.Radially therewere three areas,i.e.,the central(r/R=0-0.4),the intermittent or stable(r/R=0.4-0.8)and thenear wall(r/R=0.8-1.0)areas respectively.It was noticed that bubbles were almost non-existing atthe near wall area.Hence,according to the coalescence and splitting theory of bubbles,a two-areamodel of bubble diameter distribution was proposed and a dimensionless parameter(γ_M)regarded asan index for'quality'of fluidization was deduced.     

Exit effect on hydrodynamics of the internal circulating fluidized bed riser

This is the first time an extensive investigation has been carried out regarding the effects of riser exit geometry on pressure drop and solid behaviour inside the Internal Circulating Fluidized Bed (ICFB) riser, using different riser exit geometries at several operating conditions.The Radioactive Particle-Tracking (RPT) technique was used for solid concentration measurements and solid residence time distribution at the exit zone. Experiments were conducted using Geldart B particles, in the gas superficial velocity range of 4 to 10 m/s. Axial solid hold-up, solid residence time distribution in the exit zone, and the reflux ratio factor k_m, (defined earlier by [E.H. Van der Meer, R.B. Thorpe, J.F. Davidson, Flow patterns in the square cross-section riser of a circulating fluidized bed and the effect of riser exit design, Chem. Eng. Sc. 55 (19) (2000) 4079-4099]), were the main criteria used to investigate the impact of gas-solid separator devices implemented at the ICFB riser exit.Solid residence time distribution results and axial solid hold-up profiles provided clear evidence that the separator device at the riser exit strongly influences the hydrodynamic structure of the ICFB riser. The V-shaped riser exit geometry was found to be the optimum of all the configurations studied.     

Liquid-Solid mass transfer in a slurry bubble column and a gas-liquid-solid three-phase fluidized bed

Mass transfer coefficients between particles and liquids in a slurry bubble column and a three-phase fluidized bed containing small size particles were obtained with two mass transfer systems: (1) K⁺ –Na⁺ ion-exchange in cation-exchange resin bead beds, including anion-exchange resin beads as inert particles; (2) zinc dissolution by HCl in zinc-plated glass bead beds, and in beds of non-plated glass beads. Operating parameters were gas velocity, liquid velocity, particle diameter, and particle concentration. The dependence of mass transfer coefficients on these parameters is discussed from the viewpoint of the energy supplied into the systems. Correlations of the experimental data using dimensionless groups are compared to previous correlations.     

高密度浓相流化床中气泡的兼并与分裂特性

利用先进的高速动态分析系统对二维床中气泡的行为进行了研究,通过对所拍摄图象的分析处理．得到了不同介质流化床内形成的气泡形状、大小、聚并及分裂的基本规律和特点．实验研究表明．气泡的兼并主要是两气泡问的合并、被合并气泡总是从气泡的尾涡区曳入气泡;气泡分裂主要发生在操作气速较大或大气泡中,是由于其顶部粒子流(或“剪切流”)的侵入造成的;操作气速较低,粒度、密度较大粒子形成的流化床更易于造成气泡的湮灭。     

漏斗型导流内构件对内循环三相流化床流体力学与传质特性的影响

通过增加新型内构件来改善内循环三相流化床的流体力学与传质特性,以实现化工、环保领导中追求高氧利用率的过程。针对此过程设计了3种不同结构参数的漏斗型导流内件并设置于导流筒顶端,分别测定反应器内气含率、液相混合时间、液体循环速度、体积氧传质系数的数据并分析其变化规律,以解析内件的作用机制。实验在有效体积39L,以空气为气相、水为液相、多孔泡沫颗粒为固相的反应器中进行,研究发现：漏斗型导流内件的设置使升流区气含率平均增大10%,体积氧传质系数kLa提高了15%,液相混合时间下降10%-25%;内件的设置可以改变液体循环速度,当表观气速<0.5cm/s时,液体循环速度加快,当表观气速>0.5 cm/s时,液体循环速度下降;此外,漏斗型导流内件的结构参数变化对流化床流体力学与传质特性有较大影响。结果表明,流化床内增加新型内构件并合理设置能够实现反应器效能的提高。     

Heat transfer between an isolated bubble and the dense phase in a fluidized bed

Heat transfer between the bubble and dense phases of a bubbling fluidized bed plays a very important role in the system performance, especially for applications involving solids drying and gas‐phase combustion. However, very few experimental data are available on this subject in the literature. An experimental and modelling investigation on the heat transfer behaviour of isolated bubbles injected into an incipiently fluidized bed is reported in this paper. A new single‐thermocouple technique was developed to measure the heat transfer coefficient. The effects of bed particle type and size, and bubble size on the heat transfer coefficient were examined. The heat transfer coefficient was found to exhibit a maximum as the bubble size increased in the bubble size range investigated. The bed particle size had a comparatively small effect on the heat transfer coefficient. A simple mathematical model was developed which provides good agreement with experimental data.     

利用三相流化床半连续生产生物絮凝剂的研究

用多孔聚酯泡沫吸附固定絮凝剂产生菌XN1,比较了其和游离菌发酵产絮凝剂的情况,并分别在摇瓶和三相流化床中进行了固定化菌半连续生产絮凝剂的研究。结果表明,聚氨酯泡沫是XN1菌良好的固定化载体,具有经济、高效等特点。在优化条件下,利用固定化XN1菌摇瓶产絮凝剂可连续达12批次,12批的絮凝剂絮凝活性均>90%;而在三相流化床中产絮凝剂至少可以重复17批,且能一直保持较高的絮凝水平。研究还发现,和游离菌相比,固定化菌生产絮凝剂的生产效率可提高约4倍。     

密相流化床中介尺度流动结构的流体力学特性研究

在一套流化床冷模实验装置中对黄沙颗粒和黄沙-硅微粉 （20 μm）混合颗粒进行实验。测量固含率时间序列信号并进行统计分析,提出并建立复杂光纤脉动信号的解耦方法,实现稠密气固流中介尺度流动结构的准确识别。基于统计矩一致性原理提出气泡阈值的计算方法,通过遍历法确定气泡阈值。对气泡阈值变化规律进行分析,发现加入细颗粒有助于改善流化质量,随表观气速的增加,气泡阈值减小。对气泡、乳化和聚团三相的相分率进行统计,发现在黄沙颗粒中加入少量（5%,质量分数）细颗粒能够显著改善流化质量,细颗粒添加量过多时（10%）,对流化质量的改善将减弱。对气泡的流体力学特性进行分析,发现加入10%硅微粉后,气泡弦长增大,频率降低,速度略有降低。对颗粒聚团流体力学特性进行分析,发现随硅微粉含量增加,表观气速对聚团速度的影响减弱,聚团弦长略有减小。加入5%硅微粉后,颗粒聚团的出现频率较小且径向上分布均一。加入10%硅微粉后,聚团频率有所增大,说明加入过多硅微粉会促进聚团的形成。     

炼油废水生物流化床处理工业应用研究

介绍了一套有效体积为150m3、高径比为3.3的多导流筒生物流化床反应器工业试验装置,应用复合载体及生物菌群处理洛阳炼油厂炼油废水。用一级生化及一级沉淀两级工序代替原工艺六级组合工序。在反应温度为35℃,pH值为7,气液比为20∶1,水力停留时间为6.5h的优化试验条件下,使处理后废水中化学需氧量(COD)和氨氮(NH3-N)降解率分别大于85%和90%,即COD<100mg/L,NH3-N质量浓度<10mg/L,优于国家一级排放标准(GB8978—1996)。新工艺的占地面积、停留时间、产泥量及每吨水运行费用分别是老工艺的1/10、1/3、1/3和2/3。     

Effect of mixing state of binary particles on bubble behavior in 2D fluidized bed

In this study, a thin 2D fluidized bed was used to investigate the effect of mixing state of the binary particles on bubble behavior through the analysis of images captured by a high-speed digital camera. Experimental results show that the mixing index increases gradually with increasing gas velocity and the binary particles are in different mixing states though they are in the steady fluidization state. The maximal bubble number is near the interface of the bed when the binary particles are in the segregation state, whereas the maximal bubble number is at the bottom when the binary particles are in the well mixing state. The small bubbles are position at the bottom and are adjacent to the bed wall, while the large bubbles are mainly located in the central regions of the bed. The average bubble diameter shows the different variation trends with the different mixing states of the binary particles. The correlations estimating bubble diameter according to the mixing state of the binary particles are developed, and the computing value agrees well with the experimental data.