共查询到20条相似文献，搜索用时 93 毫秒
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气液固三相循环流化床中气固相含率轴径向的分布 总被引：4，自引：0，他引：4
对气液固三相循环流化床中气固相含率沿轴径向的分布进行了实验研究和模拟。实验结果表明：与膨胀床相比，三相循环流化床内的相间接触较为充分；固含率轴向分布的一维沉降－扩散模型模拟值与实验值吻合较好。 相似文献
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提升管三相流化床内的气液传质系数 总被引：3，自引：0，他引：3
采用溶氧电极法测定了以牛顿和非牛顿流体为液相的提升管三相流化床的气液传质系数（ｋｌａ）。证明其值受床层流动特性的影响显著，那些能提供高气含率和增大液体循环速率的操作条件也有助于ｋｌａ的提高。通过引入广义雷诺数得出了计算牛顿和非牛顿流体内ｋｌａ的关联式 相似文献
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<正>由于三相流化床反应器在石油化工、湿法冶金、环境工程和煤的液化等工业领域得到越来越广泛的应用,近年来对传统的三相流化床进行了大量的基础研究并取得了很大进展。以往的研究大部分是针对低液速(u_l相似文献
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汽液固三相流化床沸腾传热的研究 总被引：15，自引：2，他引：13
对垂直管内汽液固三相流化床沸腾传热特性进行了实验研究和理论分析,建立了沸腾传热的计算方法.实验结果表明,由于固体粒子的存在,强化了沸腾传热.传热系数比汽液两相流提高2倍左右.沸腾过程的稳定性明显提高. 相似文献
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气—液—固三相磁性流化床混沌特性研究 总被引：1，自引：0，他引：1
运用确定性混沌分析技术,研究了气－液＝固三相磁性流化床系统压力波动时间序列的混沌特性。在给定表观气、液速下,非一特征参数如最大李雅谱诺夫指数和Ｋ熵都大于零,并且随磁场强度的增加而减小,表明该系统具有混沌行为：磁场作用使气－液－因三相流动更趋有序。研究还表明,气－液－固三相磁性流化床的三个流区（散流区、链流区及磁聚区）变化可由混沌特征参数值的变化来体现。 相似文献
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气液固三相分离器的优化设计 总被引：5，自引：0，他引：5
将三相分离器的设计与ＵＡＳＢ反应器的工艺条件相结合,建立了一种改进结构的三相分离器的设计模型,可以求得分离器的最佳结构尺寸,为反应器在高负荷一稳定运行提供了依据。 相似文献
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Hydrodynamic experiments were performed using a 127‐mm diameter column with 3.2‐mm porous alumina, 3.3‐mm polymer blend, 5.5‐mm polystyrene and 6.0‐mm glass spheres, with water, aqueous glycerol solution and silicone oil as liquids, and air as the gas. The voidage at minimum fluidization fell initially to a minimum, then rose gradually with increasing superficial gas velocity, and was lower for three‐phase systems than for corresponding two‐phase (liquid–solid) fluidized beds. The compaction appears to be due to agitation by gas bubbles near the minimum liquid fluidization condition. The gas holdups agree reasonably well with the correlation of Yang et al. (1993). Curves of minimum liquid fluidization velocity, Ulmf, vs. superficial gas velocity, Ug always show Ulmf decreasing as Ug increases, initially in a concave‐downward manner, but sometimes concave‐upward. 相似文献
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K Ramesh T Murugesan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(2):129-136
Experiments were performed to study the hydrodynamics of a cocurrent three‐phase fluidized bed with liquid as continuous phase. Based on the 209 experimental data (with four liquid systems and five different particles) along with 115 literature data from six different sources on minimum fluidization velocity, a unique correlation for the estimation of minimum fluidization velocity in two‐phase (ug = 0) as well as in three‐phase systems is developed. A data bank consisting of 1420 experimental measurements for the fractional gas phase holdup data with a wide range of variables is used for developing empirical correlations. Separate correlations are developed for two flow regimes observed in this present work. The proposed correlations are more accurate and simpler to use. © 2002 Society of Chemical Industry 相似文献
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The hydrodynamics of a gas-liquid-solid circulating fluidized bed was investigated. A new regime, the three phase circulating fluidization regime, was discovered for the first time. The characteristics of this regime were compared with that of the conventional fluidization regime and the transport regime. The particle circulation rate and the gas and solids holdups in circulating fluidization regime were studied. 相似文献
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A model for liquid mixing in a gas-liquid bubble column is extended to predict gas-bubble hold-up and axial dispersion coefficient of emulsion phases in fluidized beds. Reasonable agreement is found between the proposed model which includes no adjustable parameter and the available experimental data and correlations. 相似文献
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Solid–liquid mass transfer in three‐phase fluidized beds with low‐density particles was studied using a tethered benzoic acid particle dissolution technique. Two columns with air, water and polypropylene cylinders were used for experiments. The solid–liquid mass transfer coefficient was found to increase with column diameter but decrease with tether length. The effect of tethering on solid particle movements was also evaluated using radioactive particle tracking (RPT) technique. RPT showed that tethered particles exhibited slower movements. Statistical analysis suggests that tether lengths 3 times the column radius are sufficient to reduce the effects of tethering. 相似文献
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Experiments were conducted in a turbulent bed contactor (TBC) with and without downcomer operating in Type I and Type II modes to obtain the flow regime maps. The variables include flow rate of the gas and liquid phases, size and density of the particles, bed height, free open area of the supporting grid, and diameter and weir height of the downcomer. Static, partially fluidized, completely fluidized, flooding and annular regimes are identified depending on geometric and operating conditions. The effect of these variables on flow maps is discussed and correlations are proposed for delineating the flow regimes. 相似文献
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The liquid dispersion and bubble distribution in the radial direction have been investigated in the riser of a three‐phase circulating fluidized bed whose diameter is 0.102m and 3.5m in height. Effects of gas and liquid velocities and solid circulation rate have been determined. It has been found that the radial distribution of bubbles is related closely to the liquid dispersion in the radial direction. The size and rising velocity of bubbles tend to increase as the radial position approaches to the center of the riser. The bubble size increases with increasing UG, but it decreases with increasing UL or GS in all radial positions. The radial dispersion coefficient of the liquid phase increases with increasing UG or GS, however, it tends to decrease with increasing UL. The value of Dr has been well correlated in terms of dimensionless groups based on the isotropic turbulence model. 相似文献
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Zakaria Al‐Qodah 《加拿大化工杂志》2000,78(3):458-467
The hydrodynamics of a three‐phase airlift reactor of magnetic particles has been investigated in the presence of a transverse magnetic field. Experiments were carried out in two modes: applying the magnetic field to a static bed then increasing the field flow, and applying the magnetic field to a fluidized bed then increasing the magnetic field intensity. In magnetizing the first mode and parallel to the increasing gas superficial velocity, several bed regimes were observed, including: initial packed, stabilized, and fluidized beds. On the other hand, in magnetizing last mode and while increasing the magnetic field intensity, the fluidized bed changes from a fluidized to a stabilized to frozen bed. Bed expansion before the onset of fluidization increases as the magnetic field intensity increases. Minimum fluidization velocity was found to be strongly dependent on the magnetic field intensity and the minimum stabilization intensity was also strongly dependent on the gas velocity. The magnetic field intensity also affects the bed expansion hysteresis and the liquid circulation velocity. A photocell was used to measure the water circulation rate in the downcomer of the reactor. 相似文献
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The effects of gas and liquid velocities, liquid viscosity and particle size on the radial dispersion coefficient of liquid phase (Dr) and the bubble properties in three-phase fluidized beds have been determined. A new flow regime map based on the drift flux theory in three-phase fluidized beds has been proposed.
In three-phase fluidized beds, D, increases with increasing gas velocity in the bubble coalescing and in the slug flow regimes, but it decreases in the bubble disintegrating regime. The coefficient exhibits a maximum value in the bed of small particles with increasing liquid velocity at lower gas velocities. However, it increases with increasing liquid velocity at higher gas velocities. In two and three-phase fluidized beds of larger particles (6,8 mm), Dr exhibits a maximum value with an increase in liquid viscosity at lower gas velocities, but it increases at higher gas velocities. The mean bubble chord length and its rising velocity increase with increasing gas velocity and liquid viscosity. However, the bubble chord length decreases with an increase in liquid velocity and it exhibits a maximum value with increasing particle size in the bed. The radial dispersion coefficients in the bubble coalescing and disintegrating regimes of three-phase fluidized beds in terms of the Peclet number in the present and previous studies have been well represented by the correlations based on the concept of isotropic turbulence theory. 相似文献
In three-phase fluidized beds, D, increases with increasing gas velocity in the bubble coalescing and in the slug flow regimes, but it decreases in the bubble disintegrating regime. The coefficient exhibits a maximum value in the bed of small particles with increasing liquid velocity at lower gas velocities. However, it increases with increasing liquid velocity at higher gas velocities. In two and three-phase fluidized beds of larger particles (6,8 mm), Dr exhibits a maximum value with an increase in liquid viscosity at lower gas velocities, but it increases at higher gas velocities. The mean bubble chord length and its rising velocity increase with increasing gas velocity and liquid viscosity. However, the bubble chord length decreases with an increase in liquid velocity and it exhibits a maximum value with increasing particle size in the bed. The radial dispersion coefficients in the bubble coalescing and disintegrating regimes of three-phase fluidized beds in terms of the Peclet number in the present and previous studies have been well represented by the correlations based on the concept of isotropic turbulence theory. 相似文献
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The effect of 50.8 mm diameter disc shaped mobile internals (MIs) on gas-solid contacting was studied in a large two-dimensional fluidized bed by means of non-reactive tracers. MIs were found to improve substantially the mass transfer coefficient between the bubble and dense phases. However, they also increased the gas dispersion in the dense phase. 相似文献