共查询到20条相似文献,搜索用时 0 毫秒
1.
Bubble column reactors are widely used in many industrial applications due to their simplicity of operation. Although simple to operate, bubble columns are difficult to scale-up due to the uncertainties in the estimation of some non-adjustable design parameters. One of these design parameters is the liquid phase backmixing.
The present work proposes a new correlation to estimate the liquid phase backmixing in bubble column reactors. The correlation is based on principles originally developed for flow through porous media and uses experimental data obtained over a wide range of operating conditions. This correlation is simple to use and requires parameters which are easily available or can be measured on a small scale apparatus. The proposed correlation shows a significant improvement over available literature correlations and is applicable to three phase systems as well. 相似文献
The present work proposes a new correlation to estimate the liquid phase backmixing in bubble column reactors. The correlation is based on principles originally developed for flow through porous media and uses experimental data obtained over a wide range of operating conditions. This correlation is simple to use and requires parameters which are easily available or can be measured on a small scale apparatus. The proposed correlation shows a significant improvement over available literature correlations and is applicable to three phase systems as well. 相似文献
2.
气液逆流鼓泡塔中的气含率与液速分布和数值模拟 总被引:5,自引:0,他引:5
分别采用线-线电导探针和背靠背式皮托和测定了气液逆流鼓泡塔中局部气含率和液体轴向速度的径向和轴向分布,讨论了操作条件对气含率与液体轴向速度分布的影响,利用双流体模型对塔内两相湍流流动进行了数值模拟。 相似文献
3.
An experimental investigation was carried out to evaluate energy dissipation of a divergent-convergent multistage bubble column (with convergent and divergent disks), which has been conceived, designed, and fabricated as a wet scrubber for air pollution control. In addition it has versatile use as a gas-liquid contactor in chemical and biochemical process industries. A detailed experimental investigation of pressure drop and energy dissipation has been reported by using a divergent-convergent multistage bubble column. Correlation developed for predicting energy dissipation has been found to be encouraging and highly significant from a statistical point of view. Energy consumption of the present system has been compared with other systems. 相似文献
4.
气升式内环流反应器中的液相轴向返混 总被引:1,自引:0,他引:1
在55L工作体积的气升式内环流反应器中,用羧甲基纤维素溶液模拟生物发酵液的粘性非牛顿流体行为,研究了表观气速及流体物性等参数对气升式内环流反应器中液相在上升段及下降段区域中轴向返混系数的影响,并与其他作用的实验结果进行了比较和分析。 相似文献
5.
6.
Guo-Qing Li Shou-Zhi Yang Zhao-Ling Cai Jia-Yong Chen 《Chemical Engineering Communications》1993,125(1):13-26
Liquid phase axial backmixing in the riser and downcomer sections of an airlift loop reactor with non-Newtonian fluids was investigated and determined by dynamic response technique with pulsed tracer input, dual probe detection and computer on-line analysis system under different superficial gas velocity conditions. This method was used to obtain the dispersion coefficient Dz for the individual sections of the reactor.
Kolmogoroff's theory of isotropic turbulence was applied to analyse the results of dispersion coefficient. The results show that the axial dispersion coefficient in the riser or downcomer section increases with increasing of superficial gas velocity and apparent viscosity of the fluid. The degree of mixing in the downcomer is higher than that in the riser under the experimental conditions. 相似文献
Kolmogoroff's theory of isotropic turbulence was applied to analyse the results of dispersion coefficient. The results show that the axial dispersion coefficient in the riser or downcomer section increases with increasing of superficial gas velocity and apparent viscosity of the fluid. The degree of mixing in the downcomer is higher than that in the riser under the experimental conditions. 相似文献
7.
Physical mechanisms responsible for the suspension of solid particles in semi-batch bubble column slurry reactors in bubble flow are identified, thus allowing the classification of solids into four states: free, engaged, wake-entrained and captured particles. A theory is then presented to predict the axial distribution of solids when wake-entrained and captured particles are absent. Reasonable agreement is found between the theory and experimental data obtained in this work and those reported by otherinvestigators. 相似文献
8.
Physical mechanisms responsible for the suspension of solid particles in semi-batch bubble column slurry reactors in bubble flow are identified, thus allowing the classification of solids into four states: free, engaged, wake-entrained and captured particles. A theory is then presented to predict the axial distribution of solids when wake-entrained and captured particles are absent. Reasonable agreement is found between the theory and experimental data obtained in this work and those reported by otherinvestigators. 相似文献
9.
浆态床内颗粒浓度分布的研究 总被引:4,自引:2,他引:4
1 前言浆态床内固体颗粒可以是反应物、生成物、固体催化剂或催化剂载体。固体颗粒的大小和浓度分布与其他流体力学因素相互作用,可以改变过程的传质、传热性能,进而影响反应的转化率和选择性。尤其是对强放热催化反应,作为催化剂的固体颗粒,其浓度分布不同,造成了反应器内各处反应速率的差异,从而引起各处不同的温度效应,结果导致反应速率的更大差异。Serpemen 和 Deckwer 对 F—T 合成、CO 甲烷化和丁炔二醇加氢过程中催化剂分布对转化率影响的分析,证明在设计反应器时必须考虑固体颗粒浓度分布。 相似文献
10.
通过实验研究,得到了非牛顿型浆液鼓泡塔内压力的轴向分布关联式,进而得到了塔内气含率的轴向分布式。为进一步研究非牛顿型浆液鼓泡塔流体力学行为打下基础。 相似文献
11.
In this work we characterize liquid phase mixing in a 150 L bubble column with a draft tube (internal airlift configuration) for a water-air-sand system at high solid concentrations. Liquid mixing is assessed by measuring the evolution of sodium chloride concentration after a pulse of concentrated NaCl solution is injected. Tracer concentrations were measured by means of electrical conductivity probes. The experimental set up consists of a 0.29 m internal diameter, 3 m length Plexiglas column with a conical bottom (cone apex angle of 60°) and a concentric draft tube with 0.14 m internal diameter and 2 m length. The gas superficial velocity based on the cross section of the column vaired from 0.057 to 0.22 m/s. Sand particles of 280 μm in average size were used, with slurry concentrations ranging from 120 to 500 kg/m3. From the tracer outputs, circulation time (time between peaks of the response curve) and mixing time (time required to achieve a 95% homogeneous solution) were determined after the pulse had been injected. The experimental data were analyzed by means of a tank in series model with recirculation. The circulation and mixing times were found to increase with solids concentration, and to decrease as the riser gas velocity was increased. The circulation limes were larger in continuous operation than in semibatch mode. The results show that the system has equivalent dispersion coefficients that are one order of magnitude lower than those found in a conventional bubble column. 相似文献
12.
13.
Liquid velocity profiles in a bubble column were measured with the aid of a hot-film anemometer. Two different types of profiles were detected that were characterized by the formation of a boundary layer at the column wall. Under slow flow conditions, the boundary layer is large and controls the liquid velocity profile, but in turbulent flow the boundary layer is very small and has no significant effect on the velocity profile. Microscopic and macroscopic balances were used to predict both the liquid velocity profile and the average liquid velocity. The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended. 相似文献
14.
15.
Liquid velocity profiles in a bubble column were measured with the aid of a hot-film anemometer. Two different types of profiles were detected that were characterized by the formation of a boundary layer at the column wall. Under slow flow conditions, the boundary layer is large and controls the liquid velocity profile, but in turbulent flow the boundary layer is very small and has no significant effect on the velocity profile. Microscopic and macroscopic balances were used to predict both the liquid velocity profile and the average liquid velocity.
The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended. 相似文献
The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended. 相似文献
16.
L. Antonio Est vez L. Z. Pino I. Cavicchioli A. E. S ez 《Chemical Engineering Communications》1991,105(1):231-239
This work presents an experimental analysis of the effect of the addition of a surfactant on gas holdup in a bubble column with an organic liquid phase. For the system considered, the addition of surfactant increases the gas holdup by increasing the volume of foam within the column. The surfactant concentration has negligible effect on the intrinsic gas holdup of both the bubbling and foaming regions. 相似文献
17.
For circulation in axi-symmetric (cylindrical) bubble columns, the recently developed mathematical model25,26 has been used along with the criterion of minimum circulation strength to determine the height of each circulation cell in a tall column. This is then used to derive a theoretical expression, first of its kind, for gas hold-up inside a bubble column. The predictions of this equation as well as the equation derived here for axial liquid velocity at column axis have been compared with available data and the comparison is found to be excellent for both the variables. An explicit relation is derived for the average liquid circulation velocity. The model is also used to derive an expression for liquid axial dispersion coefficient which compares almost exactly with Deckwer et al.'s4 correlation.
For circulation in two-dimensional bubble columns a new mathematical model is developed. The predictions of bubble envelope shape and bubble envelope area compare well with published data. The predictions of number of circulation cells in the horizontal direction also compare well with published data. 相似文献
For circulation in two-dimensional bubble columns a new mathematical model is developed. The predictions of bubble envelope shape and bubble envelope area compare well with published data. The predictions of number of circulation cells in the horizontal direction also compare well with published data. 相似文献
18.
鼓泡浆态反应器的传热研究 总被引:1,自引:0,他引:1
在内径为98 mm 的鼓泡浆态反应器内,研究了浸没表面与浆液之间的传热特性。在实验的条件下,模拟了浆态床 F—T 合成的操作。三相体系为氮气-液体石腊-石英砂所组成。实验中考察了不同因素对传热模系数的影响。采用95组实验数据进行关联,建立了新的传热模系数关联式:h/u_GρC_P=0.179[(u_G)~3ρ/ug]~(-0.25)(C_Pu/k)~(-0.66)该方程适用于气—液两相体系及小粒子三相浆态体系。 相似文献
19.
静止液相中气泡上升过程的分布特性 总被引:4,自引:1,他引:3
引 言两相流动现象在石油、化工、冶金、动力以及原子能等工业中普遍存在 .然而两相流动体系极为复杂 ,要认清其现象规律 ,建立合理的模型对其流动特性进行准确的预测分析 ,首先要解决的便是两相流测量技术问题 .早期人们对两相流的测量与研究主要针对总体参数 ,如截面平均空泡率 .实际上 ,对于流道内相同截面平均参数的两相流动 ,可能其气泡的径向分布不同 ,这将产生不同的两相流动形态 ,进而对传热以及摩擦压降等产生不同的影响 .近年来 ,随着计算机功能的日渐强大 ,已可以提供对两相流更加精细的计算 ,两相流模型也由最初的均相流模型发… 相似文献
20.
For circulation in axi-symmetric (cylindrical) bubble columns, the recently developed mathematical model25,26 has been used along with the criterion of minimum circulation strength to determine the height of each circulation cell in a tall column. This is then used to derive a theoretical expression, first of its kind, for gas hold-up inside a bubble column. The predictions of this equation as well as the equation derived here for axial liquid velocity at column axis have been compared with available data and the comparison is found to be excellent for both the variables. An explicit relation is derived for the average liquid circulation velocity. The model is also used to derive an expression for liquid axial dispersion coefficient which compares almost exactly with Deckwer et al.'s4 correlation. For circulation in two-dimensional bubble columns a new mathematical model is developed. The predictions of bubble envelope shape and bubble envelope area compare well with published data. The predictions of number of circulation cells in the horizontal direction also compare well with published data. 相似文献