Interaction of a charged spherical particle with a pore of a charged hydrophobic membrane in an electrolyte solution

The problem on determining the equilibrium position of a spherical charged particle entering a pore of a charged hydrophobic membrane in an aqueous electrolyte solution has been considered. The dependence of the critical pressure gradient required to overcome the electrostatic repulsion force with allowance for the surface hydrophobicity of the membrane on the position of the center of the particle on the pore axis has been determined and plotted. The presence of the maximum on the plots, which indicates the presence of a force barrier located at the entrance to the pore that prevents the particle from passing to the permeate has been revealed. The height of the barrier depends on both physicochemical (ionic strength of the solution, solution viscosity, zeta potential of the interacting surfaces, slipping length) and geometrical (particle and pore radius, rounding of the pore entrance, pore influence zones) parameters. It has been shown that the membrane surface hydrophobicity increases the magnitude of the critical pressure gradient.     

气固并流下行快速流化床反应器颗粒运动规律的研究

在内径140mm气固并流下行快速流化床,采用FCC颗粒,在局部颗粒速度、局部颗粒浓度测量的基础上,研究了床层截面平均颗粒浓度、截面平均颗粒速度、局部颗粒速度径向分布以及局部颗泣流通量的变化规律,并回归得到计算床层截面平均颗粒浓度、平均颗粒速度和局部颗粒速度的关联式,深化了对气固并流下行快速流态化的认识,为工业反应器的设计和放大提供了依据。     

催化裂化待生剂分配器性能的冷模实验评价

高效待生剂分配器对改善催化裂化再生效果具有显著的影响。设计并建造了一套能够评价待生剂分配器性能的冷模实验装置,检验了依据现有工业设计方法制造的船型和管式分配器模型以及无分配器时的颗粒横向分配性能,对比了3种再生器待生剂入口结构性能的优劣,并找出了它们存在的缺陷。结果表明,在大型工业装置中,管式分配器是唯一能够显著改善颗粒横向分配均匀性的待生剂分配器,但它必须消耗大量的输送风,会因此增加装置能耗,并对待生管路的颗粒输送能力产生不利影响;船型分配器对颗粒横向分配均匀性的改善作用十分有限,尤其是在大型工业装置中。对于所有待生剂入口结构,增加输送风量能够显著改善颗粒横向分配的均匀性,增加松动风量也能改善船型和管式分配器的性能,但总体上效果不如增加输送风显著,而增大催化剂循环量后,3种待生剂入口结构的颗粒横向分配均匀性均有一定程度的恶化。由于受管内气 固相流型转变的影响,管式分配器存在一个临界输送气速,在此临界气速以上,颗粒横向分配均匀性可以显著改善。上述研究结果可为工业待生剂分配器的优化设计以及新型高效待生剂分配器的开发提供借鉴。     

Numerical analysis of hydroabrasion in a hydrocyclone

The velocity profiles and separation efficiency curves of a hydrocyclone were predicted by an Euler–Euler approach using a computational fluid dynamics tool ANSYS-CFX 14.5. The Euler–Euler approach is capable of considering the particle–particle interactions and is appropriate for highly laden liquid–solid mixtures. Predicted results were compared and validated with experimental results and showed a considerably good agreement. An increase in the particle cut size with increasing solid concentration of the inlet mixture flow was observed and discussed. In addition to this, the erosion on hydrocyclone walls constructed from stainless steel 410, eroded by sand particles (mainly SiO₂), was predicted with the Euler–Lagrange approach. In this approach, the abrasive solid particles were traced in a Lagrangian reference frame as discrete particles. The increases in the input flow velocity, solid concentration, and the particle size have increased the erosion at the upper part of the cylindrical body of the hydrocyclone, where the tangential inlet flow enters the hydrocyclone. The erosion density in the area between the cylindrical to conical body area, in comparison to other parts of the hydrocyclone, also increased considerably. Moreover, it was observed that an increase in the particle shape factor from 0.1 to 1.0 leads to a decrease of almost 70 % in the average erosion density of the hydrocyclone wall surfaces.     

Numerical simulation of predicting and reducing solid particle erosion of solid-liquid two-phase flow in a choke

Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid particle movement as well as particle erosion characteristics of the solid-liquid two-phase flow in a choke. The corresponding erosion reduction approach by setting ribs on the inner wall of the choke was advanced. This mathematical model includes three parts： the flow field simulation of the continuous carrier fluid by an Eulerian approach, the particle interaction simulation using the discrete particle hard sphere model by a Lagrangian approach and calculation of erosion rate using semiempirical correlations. The results show that particles accumulated in a narrow region from inlet to outlet of the choke and the dominating factor affecting particle motion is the fluid drag force. As a result, the optimization of rib geometrical parameters indicates that good anti-erosion performance can be achieved by four ribs, each of them with a height （H） of 3 mm and a width （B） of 5 mm equaling the interval between ribs （L）.     

基于格子Boltzmann方法颗粒团聚物曳力系数的数值模拟及应用研究

应用气固两相流动的格子Boltzmann-离散颗粒运动模型,气体流动采用格子Boltzmann方法的D2Q9模型,固体颗粒运动采用牛顿第二运动定律计算,壁面采用具有二阶计算精度的半步长反弹边界条件,数值模拟了循环流化床提升管内颗粒团聚物的运动过程。模拟结果表明,颗粒团聚物的气固相间曳力系数随颗粒团聚物的空隙率和雷诺数的增大而减小;拟合得到基于格子Boltzmann方法的气固相间曳力模型;采用基于格子Boltzmann方法的气固相间曳力模型的欧拉-欧拉双流体模型模拟循环流化床提升管内颗粒相密度和颗粒质量流量径向分布,模拟结果与实验结果很接近。     

粒子冲击钻井系统中粒子分选装置的研制

粒子冲击钻井过程中,能否快速高效地分离出已破碎粒子直接关系到粒子冲击钻井的效率。为此,以综合利用粒子旋转的离心力和外部注入气流的气流拖拽力来实现好、坏粒子分离的新思路为指导,设计出了由分选装置、引风机2个部分组成的粒子分选装置。进而通过调节电机转速和引风机的引风量参数,实验研究了分选装置的分离效果及其影响因素。结果认为:1钢粒子的分散性是影响分级效率和分离处理量的重要条件,获得较大力场可为获得较好分散创造有利条件;2钢粒子在分选装置中旋转越快,分选装置分级效率越高;3粒子直径越大,分选装置分级效率和处理量越大;4好坏粒子混合物中的坏粒子的相对含量会影响分级效率,坏粒子含量越低,分级效率越高。实验结果表明,设计的粒子分选装置能够有效实现好坏粒子的分离,这为粒子冲击钻井技术的实现提供了设备上的支持和理论上的保障。     

Microstructure effects on the detonation velocity of a heterogeneous high-explosive

ABSTRACT

Although numerous methods exist for the theoretical calculation of detonation parameters of explosives, few thermodynamic-hydrodynamic-based theoretical codes take into account particle size. The basis for their computational analysis is primarily focused on the equation of state of the detonation products, heat of formation, and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing cyclotrimethylene-trinitrmaine (RDX). The principal characteristics examined were the average particle size of RDX, amount of HMX impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. % solids and 27 wt. % polyurethane binder. An equation is developed that accurately predicts detonation velocity based on average particle size, density, and manufacturing process for RDX. The model underscores the significance of the relationship between the average particle size and detonation velocity. Compositions containing smaller average particle sizes of RDX generate higher detonation velocities. A 100 micron increase in the average particle size was shown to decrease detonation velocity by 161 m/s for the monomodal polyurethane compositions used in this study. The relevance of using statistical models for selecting characteristics that result in optimum explosive performance is addressed.     

循环流化床颗粒输送斜管的压力脉动特性

以循环流化床输送斜管为研究对象,通过改变颗粒质量流率,测量斜管内蝶阀上、下两处的动态压力。结果表明,随着颗粒质量流率增加,蝶阀上、下方颗粒的流动形式均发生变化,斜管内的颗粒流态发生变化,动态压力的波动幅度逐渐增加。蝶阀下方的动态压力标准偏差与颗粒质量流率呈线性关系,能够用于表征循环流化床的颗粒质量流率。压力脉动的小波分析表明,斜管内蝶阀上、下方均存在一个主频,是由于斜管自身的流动结构所致,但蝶阀下方还存在一个次频,是由于气体脉动以及气、固两相的相互作用所致,且次频所占能量随颗粒质量流率增加而降低。斜管下料产生的脉动压力是一种低频压力,是斜管振动的激振源。     

扩径段参数对变径提升管内气固流动的影响

在内径20mm、高3m的提升管冷模装置上对变径结构提升管内部固体颗粒分布情况进行了研究。实验结果表明,提升管扩径段的底部锥角主要对扩径段下部的催化剂浓度和颗粒返混产生影响,60°左右的底部锥角可以减小催化剂的返混,达到较高的固含率,并控制合适的停留时间。选择较小的顶部锥角既可以减小因近边壁处与顶部锥角直接碰撞而发生滑落造成的催化剂返混,又可以实现缩径段催化剂的短停留时间。相对其它角度,60°的顶部锥角可以得到较为均匀的催化剂径向分布。扩径段的高度对扩径段内固含率的影响较为显著。当扩径段高度日与扩径段的直径D之比值在8左右时,既能实现300～400kg／m^3左右的催化剂密度,又能减小返混。     

橡胶颗粒复合调剖体系在复杂断块油田的应用

采用传统的调剖体系对文明寨、卫城中高渗复杂断块油藏进行多轮次调剖后,调剖效果变差,需要研究新的经济适用的调剖体系。橡胶颗粒调剖体系由橡胶颗粒、交联聚合物和聚丙烯酰胺等组成,应用砾石充填方法对橡胶颗粒体系与地层孔喉匹配性、橡胶颗粒调剖体系在不同渗透率填砂管中的调剖作用进行了研究;通过用不同粒径和浓度的橡胶颗粒与不同浓度的交联聚合物和聚丙烯酰胺配比研究,确定了最佳注入浓度配比。2008年以来,在文明寨、卫城油田进行了9口井的应用,对应油井有较明显的增油降水效果,累计增油773t,投入产出比1∶1.75。该橡胶颗粒复合调剖体系有很好的推广应用前景。     

Numerical Simulation of Particle Concentration in a Gas Cyclone Separator

The particle concentration inside a cyclone separator at different operation parameters was simulated with the FLUENT software. The Advanced Reynolds Stress Model (ARSM) was used in gas phase turbulence modeling. Stochastic Particle Tracking Model (SPTM) and the Particle-Source-In-Cell (PSIC) method were adopted for particles computing. The interaction between particles and the gas phase was also taken into account. The numerical simulation results were in agreement with the experimental data. The simulation revealed that an unsteady spiral dust strand appeared near the cyclone wall and a non-axi-symmetrical dust ring appeared in the annular space and under the cover plate of the cyclone. There were two regions in the radial particle concentration distribution, in which particle concentration was low in the inner region (r/R≤0.75) and increased greatly in the outer region (r/R>0.75). Large particles generally had higher concentration in the near-wall region and small particles had higher concentration in the inner swirling flow region. The axial distribution of particle concentration in the inner swirling flow (r/R≤0.3) region showed that there existed serious fine particle entrainment within the height of 0.5D above the dust discharge port and a short-cut flow at a distance of about 0.25D below the entrance of the vortex finder. The dimensionless concentration in the high-concentration region increased obviously in the upper part of the cyclone separation space when inlet particle loading was large. With increasing gas temperature, the particle separation ability of the cyclone was obviously weakened.     

Evaluation of Asphaltene Instability and a Chemical Control During Production of Live Oils

Abstract

In this study, the propensities of reservoir fluids sampled from South America to precipitate asphaltenes under realistic production conditions of pressure, temperature and/or composition (e.g. lift gas operation and chemical treatment) were evaluated. Novel techniques, namely a laser-based solids detection system (SDS) and a high pressure microscopy (HPM) coupled with in-house imaging software package for particle size analyses, have been simultaneously used to measure and compare the incipient conditions for precipitation of asphaltenes from live oils as well as the associated morphological and size distribution changes. The combination of qualitative information such as particle morphology and quantitative data such as particle size distribution was particularly very valuable in evaluating the effectiveness of Asphaltene Inhibitors (AI).     

Estimation of bitumen emulsion dispersion using a light scattering method

Petroleum bitumen in the emulsified state is widely used as a binder in road and civil construction. Along with traditional quality parameters of bitumen emulsions the particle size is considered to be very important characteristic. The particle size of the dispersed phase affects the setting rate and viscosity of bitumen emulsions. The complete data on the particles size distribution can be obtained using such technical methods as light scattering and microscopy. In the study bitumen emulsions with three types of surfactants (cationic, nonionic, zwitterionic) have been prepared and their viscosity and decay index have been determined. The emulsions also have been studied with a microscope, as well as by the method of dynamic light scattering. The dynamics of particle size changes of the bitumen emulsions has been compared with the dynamics of the change in the basic parameters of the emulsions, such as viscosity and decay index, and the correlation between them has been found. Thus, using a modern laser and optical equipment, it is possible to estimate the quality of emulsions and, if necessary, to correct their composition.     

组合流化床燃烧器烧焦管内固含率的径向分布研究

在组合流化床燃烧器的冷态实验装置上,以空气一石英砂颗粒为流化介质体系,在烧焦管内表观气速（u。）为3．156～5．989m／s,颗粒循环强度（G8）为40．8～229．4kg／（m2·s）的条件下,采用光纤颗粒浓度测量仪对烧焦管内床层径向局部位置的固含率（ε8）进行了测定。结果表明,烧焦管内ε8沿床层径向呈中心稀边壁浓的环一核形分布形态,呈现出非均一的相结构;ε8随ug的升高而减小,且随Gs的升高而增大,这种影响规律在烧焦管的边壁区比中心区更为显著。根据实验数据关联出截面平均固含率不变条件下的径向局部ε8的计算式,所得计算值与实验值基本吻合。     

Study of the Spatial Distribution of Burning Particles in a Pyrotechnic Flame Based on Particle Velocity

The burning particles in the pyrotechnic flame play an important role in the ignition and spectral radiance of the pyrotechnic. We used particle image velocimetry (PIV) and high-speed camera (HSC) photography to investigate the 3D spatial pattern and velocity of the burning particles in the flame of pyrotechnics. The original images captured by the HSC were preprocessed through threshold selection, image bivalency, edge detection, and contour extraction and segmentation to obtain the particle coordinates and velocity. Consequently, the particle tracking model was established and the velocity and spatial distribution of the burning particles were obtained. A comparison of the flame flow field with particle image velocimetry demonstrated the typical characteristics of the two-phase flow of the pyrotechnic flame between burning particles and gas. Compared with the convergent gas flow field, the higher velocity burning particles had a discrete distribution in the “comet tail” shape region and showed the same direction of motion as the flame flow field, whereas the lower velocity burning particles had larger outlying regions and showed inconsistent directions of motion. The flow field of the burning particles was more chaotic than the flame flow field of the burning pyrotechnics.     

Experimental analysis of pressure characteristics of catalyst powder flowing down a cyclone dipleg

An experiment was carried out for investigating pressure behavior of catalyst powders,with a Sauter mean diameter of 63.6 urn,(lowing downward in a cyclone dipleg with 150 mm inner diameter and 9000 mm high.Time mean pressure and time series of pressure fluctuations were measured at different axial positions in the dipleg with particle mass fluxes ranging from 50.0 to385.0 kg m~(-2) s~(-1).The experimental results showed that the time mean pressure in the dipleg increased progressively from the top section to the bottom section.The experimental phenomena displayed that the fluidization patterns in the dipleg can be divided into two types on the whole,namely the dilute-dense coexisting falling flow and the dense conveying flow along the dipleg.In the dilutedense coexisting falling flow,the dilute phase region was composed of a length of swirling flow below the inlet of dipleg and a dilute falling flow above the dense bed level.With increasing particle mass flux,the dilute-dense coexisting falling flow was gradually transformed to be the dense conveying flow,and the exit pressure of the dipleg increased considerably.The pressure fluctuations were closely related to the fluidization patterns inside the dipleg.In the dilute-dense coexisting falling flow,the pressure fluctuations in the dilute flow region originated from particle clusters,propagating downward as a pressure wave:however,the pressure fluctuations in the dense flow region originated from rising gas bubbles,propagating upward.When the dense conveying flow was formed in the dipleg.the pressure fluctuations originated mainly from instability of the feed and the compressed gas,propagating downward.The standard deviation of the pressure fluctuations indicated that the intensity of pressure fluctuations first increased and then decreased with increasing particle flux.     

国产CMAX 120型催化剂在环管聚丙烯装置上的应用

在30万t/a环管聚丙烯(PP)装置上,进行了国产CMAX120型催化剂的应用试验,并与该装置原用进口催化剂作了对比。结果表明,与进口催化剂相比,CMAX120型催化剂的平均活性略低、氢调性略差、等规度调节性略优;2种催化剂所得产品PP粉料的粒径分布相差较大,其中CMAX120型催化剂所产PP中细粉含量明显增加,平均粒径较小;CMAX120型催化剂所产PP除清洁度略差于进口催化剂生产的PP产品外,其他质量指标均相当,产品质量合格。     

多流型新型提升管冷模实验研究

在高8.1 m、扩径段直径120 mm和等径段直径50 mm的提升管冷模实验装置上对一种底部变径结构和设置有内部导流筒的新型提升管进行了研究,考察了操作条件对其轴向和径向固含率与颗粒速度的影响,以及导流筒及环隙内的固含率和颗粒速度的分布。结果表明,与传统提升管相比,该新型提升管内可同时存在多种流型,提升管底部扩径段内为径向较为均匀的密相床,上部等径段为稀相床;导流筒的存在对从斜管下来的固体颗粒产生重新分配的作用;导流筒和环隙内存在较大的固含率和颗粒速度差;由于导流筒的抽吸作用,在提升管底部扩径段内,管中心处催化剂颗粒向上运动,边壁处催化剂颗粒向下运动。