Experimental Simulation of the Reactor Section of Fluid Cokers: Comparison of FCC and Fluid Coke Particles

The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ～20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core‐annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers.     

射流流化床内流体力学行为的模拟研究

以流化床应用为代表的气固流动系统是许多化工过程中的重要组成部分 ,CFD( computational fluid dynamics)方法能够为其优化设计和放大提供所需要的信息 .本文采用双欧拉模型 ,与 Gidaspow等的实验结果进行了对比 ,模拟了二维射流流化床内气泡的形成规律 ,得到了带锥型分布器的流化床内瞬时空隙率和气固相速度分布等流体力学参数 .对锥型分布器流化床的实验结果表明 ,模拟得到的气泡的形状与实验现象相接近 .     

Particle velocity and solids circulation rate in a jet-spouted bed

Radial distribution of particle velocities, solids circulation rate and radial variation in bed voidage in a jet-spouted bed were investigated in a 0.2 m diameter conical-cylindrical column. The upward particle velocity is strongly dependent on gas velocity and its radial profile is the Gaussian. The solids circulation rates are of the same order of magnitude as those in a conventional spouted bed and are proportional to the gas velocity. Estimation of the variation in bed voidage in the radial direction revealed that the annulus voidage of about 0.90 was greater than the spout voidage of around 0.70. This tendency is contrary to that in a conventional spouted bed.     

Homogeneous Fluidization Characteristics of Vibrating Fluidized Beds

The effects of vibration parameters, operating conditions and material properties on fluidization quality were investigated by the measurement and analysis of voidage fluctuation signals in a vibrating fluidized bed with a diameter of 148 mm. The fluctuation deviation of the bed voidage and the enhancement index of the bed derived can describe bed homogeneity and its extension. A new criterion of homogeneity, consisting of the material parameter (Ar), operating parameters (H₀, u/u_mf) and vibration parameters (a, ω), is proposed to predict a suitable range of homogeneous fluidization. Experimental results on eight kinds of solids, five static bed heights and different vibration parameters were used to propose guidelines for the reasonable selection of operating conditions for vibrating fluidization and better operating conditions.     

Voidage Measurement for a Moving Plug in Dense Phase Pneumatic Conveying Using Two Different Methods

Two simple ways to measure voidage in a moving plug in dense phase pneumatic conveying have been explored, along with voidage behavior and other parameters. The first method (bulk solid method) determines the average voidage for a single plug, by measuring the length and the weight of the plug, while the second method (Ergun's method) determines the voidage along the plug length from plug head to tail by using the Ergun equation. The experiments were performed under different experimental conditions of plug lengths, gas velocities, and materials. The results from both methods showed varying degrees of agreement, depending on the material transported. The measurements also found that the voidage varied only slightly with the plug velocity. However, it did vary more within the plug (e.g., plug head, middle of plug, and plug tail).     

ANALYSIS OF AERODYNAMICS AND HEAT TRANSFER IN VIBRO-FLUIDIZED BEDS

Recent experimental data on aerodynamic and heat transfer characteristics of vibro-fluidized beds of model particles are presented and discussed in the light of the limited prior information. An analysis is presented for the bed dynamics with supporting experimental data. The predicted results for bed flight time, pressure drop and average voidage are shown to agree favorably with experimental data. On the basis of experimental results, a theoretical model and a simple design chart are presented which may be used to determine favorable operating ranges for a vibro-fluid bed apparatus.     

The capture and release of biomass using a high voidage fibrous filter (marked revision)

This paper is concerned with the capture and subsequent release of wastewater biomass using a high voidage filter. A semi-automated experimental rig was developed where both the hydraulic response of the filter and the capture of biomass were investigated as a function of throughput and filter voidage. The hydraulic response of the clean filter was found to correlate well with the Jackson-James permeability model for gas filtration, and the hydraulic measurements give information about the average shear stresses present during the initial stages of biomass deposition. Biomass capture in the filter was achieved for low Reynolds number throughput followed by a characteristic breakthrough of particles to the effluent stream. Subsequent release of biomass and regeneration of the filter was accomplished by high intensity oscillation of the fluid in the filter, causing the re-suspension of the biomass, which could then be drained from the column. The performance of the filter is evaluated in terms of its cycle and energy efficiency, and its potential for scale-up.     

应用不稳定压力试井资料定性分析注采平衡及井间连通性

介绍了应用不稳定压力试井资料，定性分析注采平衡及井间连通性的新方法。该方法通过对比分析同一井历次试井所得压力恢复曲线的特点，或综合分析同一井组各井的试井压力恢复曲线的特点，来确定油气井的注采平衡状况；如果在同一时期内对同一井组上所有井进行关井测试，再把所得到的压力恢复曲线绘在同一半对数图上，即可定性分析出井间连通性。文章还引用实例分析，证明了此种分析方法与其它分析方法所得结果基本一致。     

中空玻璃微珠粒度分布分形特征及其与空隙率关系的研究

为研究中空玻璃微珠粒度分布分形特征与空隙率的关系,测量了6种中空玻璃微珠的粒度累积分布,用统计学概念与分形理论分别考察了中空玻璃微珠的粒度分布法则及其分形特征。结果表明:中空玻璃微珠粒度累积频率与相应的上限粒径的对数值有良好的线形关系,粒度符合对数正态分布法则;各中空玻璃微珠的粒度累积频率与粒径与最大粒径比值的双对数值呈线形关系,相关系数在0.95～0.98之间,强的相关表明各中空玻璃微珠的粒度分布的分形结构是客观的;随着中空玻璃微珠粒度分布分形维的增加,其空隙率减少。     

库布齐风积沙对各分级河砂的填充效应

为探究风积沙部分取代河砂带来的填充效应对细骨料空隙率的影响规律,采用库布齐沙漠边缘的风积沙,以不同取代率取代粗、中、细3级共9种细度模数的河砂,测试其对细骨料空隙率的影响;同时采用PFC3D离散元软件进行相应细骨料的堆积模拟,确定了库布其风积沙对不同分级、不同细度模数河砂的最优取代率.另外,采用与库布其风积沙级配一致的河砂进行了相似的试验与模拟探究,通过对比前期的试验结果,确定了库布齐风积沙对不同细度模数河砂、不同取代率情况下的细骨料空隙率粒形影响因子.