共查询到17条相似文献,搜索用时 140 毫秒
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狭缝式矩形喷动床中多粒度颗粒体系的最大喷动压降 总被引:2,自引:0,他引:2
在 15 0 mm× 5 0 mm× 110 0 mm的矩形喷动床中 ,研究了单一粒径体系和二组分及三组分混合粒径颗粒体系的最大喷动压降受颗粒粒径及粒度组成、静止床高和气体入口狭缝宽度的影响情况。实验采用宽度为2、4、6 mm三种宽度的狭缝式气体分布板 ,实验物料为单一粒径分别为 1、1.5、2 mm的玻璃珠。实验表明矩形喷动床的最大喷动压降与上述三种影响因素都有关系。本文还给出了最大喷动压降随这三种因素变化的实验关联式 相似文献
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在200mm×15mm×600mm的矩形喷动床中,研究了3种不同颗粒体系的流型变化。提出了采用logE[R(t,τ)/S(t,τ)] logτ关系图形特征对流型进行识别的方法。结果表明,根据实测的床层压力波动信号获得的logE[R(t,τ)/S(t,τ)] logτ关系图形,可以客观地识别喷动床中存在3种流型,即固定床、稳定喷动和不稳定喷动。 相似文献
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基于截面200 mm×20 mm,高1600 mm,锥角60°的矩形喷动流化床,以二组分混合颗粒、单一组分球形颗粒及非球形颗粒为物料进行最大喷动压降的实验研究.结果表明,最大喷动压降随静止床高、颗粒密度、颗粒球形度及二组分混合颗粒体系中沉积组分分率增加而增大,随流化气速增大而减小;增大颗粒粒径或喷口宽度,呈现先减小后增... 相似文献
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Minimum spouting velocity and segregation behaviour of binary mixtures of particles differing in size have been studied. The experiments were carried out in a bed of 20 cm diameter at superficial gas velocities up to 1.3 Ums by use of silica sand of four different particle sizes from 0.655 to 2.23 mm. An empirical equation was proposed for the minimum spouting velocity of binary mixtures. The effects of the particle size difference and the superficial gas velocity on segregation were investigated. Results showed that considerable radial segregation as well as axial segregation occurred even for high gas velocity under the condition of large particle size difference. 相似文献
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M.S. Bacelos 《Powder Technology》2007,174(3):114-126
This paper aims to analyze air-solid flow behavior in conical spouted beds composed of glass bead mixtures coated by glycerol. Four mixtures of glass beads are used as the solid phase. Although these mixtures have the same mean Sauter diameter, each one is characterized by a different size distribution function (mono-sized; flat, Gaussian or binary size distribution). When glycerol is added to the bed of these particles, which are spouted by air, the gas-solid flow characteristics are changed due to the growth of interparticle forces; however, the trends of these changes are affected by the glass bead mixture type as well as by the concentration of glycerol. For beds of mono-sized particles, the minimum spouting velocity is maintained almost unchanged as the glycerol concentration rises; while, for beds of inert particle mixtures, this velocity increases, becoming greater for flat and binary size distribution particles. Conversely, the minimum spouting pressure drop decreases as the glycerol concentration rises for all beds of particles used. Based on theoretical prediction of interparticle forces, it is shown that these changes in the minimum spouting conditions can be explained by the magnitude of these forces. 相似文献
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A cylindrical gas-liquid-solid spouted bed, driven exclusively by gas flow, has been developed with a high potential for use in biochemical processes, such as a biological wastewater treatment. A plexiglass column with a 152 mm inner diameter was used in combination with a 53 mm inner diameter plexiglass draft tube. Three particle types were studied with densities ranging from 1044 kg/m3-1485 kg/m3 and average particle sizes ranging from 0.7-2.5 mm. Four flow regimes were observed when increasing the gas velocity, including fixed bed, semispouted bed, full spouted bed, and internal circulating fluidized bed. The transition gas velocities between those regimes were experimentally measured and termed as minimum spouting velocity, full spouting velocity, and minimum circulating velocity, respectively. A measurement of the downward particle flux in the annulus was used to identify the minimum spouting velocity, while the particle velocity and dense phase retraction in the annulus were monitored for the full spouting and minimum circulating velocities. All regime transition velocities increased with more dense particles and longer draft tubes. The minimum spouting velocity and full spouting velocity were not affected when varying the nozzle-tube gap, while the minimum circulating velocity increased with longer nozzle-tube gaps. Experiments without a draft tube were carried, though the spouting stability was significantly reduced without the draft tube. 相似文献
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Jet spouted beds that consisted of a transparent Plexiglas cylindrical column of 1 m high and a conical base with cone angles of 30°, 36°, and 40° were used in this study. The particles used were spherical glass beads with an average diameter of 1.7, 2.1 and 3 mm, respectively, and particle size of 2.2 – 3.1 mm, non‐spherical rice particles. The effect of size and shape of particles, and static bed height on the minimum jet spouting velocity, and standard deviation of pressure fluctuations, was investigated. The results show that the minimum jet spouting velocity and pressure drop increased as the bed height and particle size increased. The minimum jet spouting velocity could be determined from the plot of standard deviation of pressure fluctuations vs. superficial gas velocity. The results obtained were in close agreement with the results of other methods in the literature. 相似文献
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细颗粒喷动床的流体力学特性 总被引:3,自引:1,他引:2
在直径186 mm的喷动床中考察了细颗粒(dp=0.241~0.874 mm)体系的流体力学性质及夹带和磨损特性.采用不同的喷嘴直径(Di=6~14 mm)和锥底顶角(θ=45°~80°)对其操作状态进行了研究,发现当Di/dp<19~21时可以形成稳定喷动.随着气体速度的增加,床层依次出现固定床、稳定喷动、不良喷动和腾涌等4个流动区域.实验测量的最小喷动速度与Mathur-Gishler关联式的误差在±15%之内.采用γ射线扫描仪测量了固体密度分布,结果表明喷动区的固体密度随高度的增加而增加,环流区的密度比松堆密度大3%~10%.颗粒的磨损和夹带随着气速的增大而增大,在稳定有序的喷动状态下变得最小. 相似文献
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Xuejiao Liu Wenqi Zhong Xiaofeng Jiang Baosheng Jin 《American Institute of Chemical Engineers》2015,61(1):58-67
Spouting behaviors of cylindroid and spherical particles in a spouted bed are experimentally investigated. The characteristics of flow pattern and pressure drop of the binary mixtures are figured out and three kinds of cylindroid particles with different sizes and shapes are involved in experiments to discuss effects of particle size and shape on the spouting behaviors in beds. The emphasis is laid on the influence of the volume fraction of cylindroid particles, Xc, on the spouting phenomena, including the total pressure drop, the minimum spouting velocity, and fountain height. Results show that, the shapes and sizes of cylindroid particles, mainly including equivolume diameter and aspect ratio, significantly affect the spouting behaviors. There is a maximum volume fraction, Xc,max, for each kind of cylinders to maintain the stable fountain at a certain gas velocity. With the same gas velocity, Xc,max is lower for the cylinders with higher aspect ratio. © 2014 American Institute of Chemical Engineers AIChE J, 61: 58–67, 2015 相似文献