Computational Investigation of an Industrial Cyclone Separator with Helical‐Roof Inlet

An industrial cyclone separator with helical‐roof inlet TsN‐11 has been numerically investigated as to pressure and flow field, pressure drop, fractional efficiency, and particle trajectories inside the cyclone. The turbulence was modeled with Reynolds stresses and large eddy simulations (LES) based on three different subgrid‐scales (SGS). The results with the different setups were compared to experimental data from previous studies. For a proper calculation of the flow field, LES combined with a dynamic SGS model was used for predicting cyclone performance. Individual particles were tracked through the unsteady flow field using the Lagrangian approach. The results of the numerical calculations of the tangential and axial velocity, pressure drop, and cut size are in good agreement with experimental measurements.     

旋风分离器在柴油加氢精制装置中的应用

常减压、焦化、催化柴油等经加氢精制反应器反应后,原料中的硫被循环氢还原,反应产物经换热、分离器分离,液相产品进入汽提塔进行进一步分离,气相进入循环氢脱硫系统。进入循环氢脱硫塔的循环氢不可避免的存在少量的烃类和轻浮油,这些液滴使得循环氢脱硫塔内溶剂发泡,同时又造成胺液损失,严重的影响了脱硫效果。采用上海华畅环保设备发展有限公司的旋流器技术后,脱硫塔效果得到明显改善。     

新型双蜗壳式旋风分离器内流场分布的试验研究

采用五孔球探针测试仪对一种新型双渐开线入口结构旋风分离器分离空间的三维速度和压力分布进行了测量。试验结果表明,该旋风分离器分离空间的切向速度呈现“驼峰”分布,最大值达到29vp,离心力场较强,上行流区的静压变化为顺压梯度,有利于降低压力损失;在流场测量的基础上,利用积分离散化的方法计算了分离空间的下行流量,指出控制短路流和分离空间下端的旋涡流动是进一步的优化方向。     

Large Eddy Simulation Investigation of an Industrial Cyclone Separator Fitted with a Pressure Recovery Deswirler

A cyclone fitted with a deswirler of original design has been investigated by means of large eddy simulation. Installation of the deswirler reduces significantly the positive static pressure near the wall as well as the negative static pressure in the central region. It also decreases the maximum tangential velocities in the main separation zone. The deswirler enables a substantial reduction of the backward flow at the gas outlet and a more uniform distribution of the axial velocities at the gas outlet. It also considerably reduces pressure losses in the vortex finder lowering the cyclone pressure drop by almost about one third but it deteriorates the collection efficiency of particles with diameters of less than 8 µm, thus increasing the cut size.     

丙烯腈反应器三级PV型旋风分离器大型冷模试验研究

针对丙烯腈反应器操作条件 ,运用旋风分离器尺寸分类优化设计理论 ,设计了三级PV型旋风分离器 ,并确定了合理的大型冷模试验方案。试验结果表明 ,三级PV型旋风分离器分离性能优于国外引进的型旋风分离器 ,它可以满足丙烯腈生产的要求。     

顺流式旋风分离器的分离性能研究

采用冷态对比实验研究从灰斗引出排气管的新型顺流式旋风分离器的分离性能。试验考察了导流体直径、导流体长度、导流体-排气管口距离、排气口直径等结构因素对分离性能的影响以及不同入口气速条件下的分离性能。研究结果为该类型旋风分离器的优化设计提供了依据。     

Experimental and Numerical Investigations of a Dual‐Stage Cyclone Separator

Cyclone separators can be utilized in parallel to increase particle collection efficiency. However, this leads to a maldistribution problem that causes separation performance deterioration. To improve the flow distribution, a dual‐stage multicyclone separator (DSCS) was designed, containing a tangential‐inlet circle pathway cyclone array, an axial‐inlet radiation pathway cyclone array, and a cylindrical outer chamber. Experimental and computational fluid dynamics results revealed the gas‐particle flow distribution through multicyclone arrays. Effects of flow distribution on particle deposition were investigated experimentally. Particle trajectories inside the cyclone separators were also observed. The multicyclone array proved to generate a uniform inlet velocity distribution. The proposed cyclone separator can be considered as an option to accomplish dilute gas‐particle separation.     

Efficient Gas‐Liquid Cyclone Device for Recycled Hydrogen in a Hydrogenation Unit

An efficient cyclone device for removing hydrocarbon fog droplets in recycled hydrogen was developed based on experimental studies and industrial application. Conditions for optimal separation efficiency of the gas‐liquid cyclone were determined. The device reduced raw material losses and desulfurizer consumption and improved desulfurization efficiency, thereby increasing the purity of the cycled hydrogen and decreasing the mean molecular weight of gas. Energy consumption of the cycled hydrogen compressor as well as the pollution discharge of the hydrogenation unit were also diminished.     

The Meaning of Droplet‐Droplet Interaction for the Wet Flue‐Gas Cleaning Process

In most large coal‐fired power plants an absorption process with a limestone suspension is applied today. The flue gas proceeds upwards through a series of spray headers that introduce a uniform liquid flux of droplets of the limestone suspension. These droplets resist the gas flow and provide a large mass transfer surface area required for the SO₂ removal process. During the spray overlapping the collision of the droplets may lead to a coagulation or a separation process depending on certain collision parameters, such as surface tension, impact velocity and collision geometry. A model for droplet collisions was developed and implemented in a two‐phase flow simulation by Euler‐Lagrange. The model is based on experimental investigations with overlapping sprays.     

Effect of Rotor Disc Diameter on Holdup,Axial Dispersion and Droplet Size in a Taylor‐Couette Disc Contactor

Application of liquid‐liquid extraction is on a steady rise. Although there are considerable designs of extraction devices, equipment design and optimization is still on the research agenda. Utilization in the biorefinery industry or metallurgy requires robust technologies and equipment. The simple design and stable operation performance of the Taylor‐Couette disc contactor suffices the technical needs for these harsh operation conditions. The effect of different rotor disc diameter on the dispersed phase holdup, axial dispersion, and droplet size was investigated. It was shown that with smaller rotor disc diameter stable operation is still feasible but higher axial backmixing has to be expected.     

Gas hold‐up in stirred tank reactors

Based on a study of the gas hold‐up data for stirred tank reactor generated in the present work and the data available in the literature for large stirred tank reactors (T = 0.57 m to 2.7 m) equipped with disc turbines and pitched blade downflow turbines a correlation is presented which reliably predicts gas hold‐up data over wide range of system configurations and operating parameters. The parameter used, N/N_cd, relates gas hold‐up at impeller speed N with respect to the gas hold‐up at minimum impeller speed for complete dispersion of the gas, N_cd. It is shown that the gas hold‐up data of different workers when compared on the basis of N/N_cd, shows unanimity.     

Lithium Extracting from Zinnwaldite: Economical Comparison of an Adapted Spodumene and a Direct‐Carbonation Process

Lithium is used in a variety of everyday objects. The most important field of application is as components of battery electrolytes and electrodes. Next to salar brines, commercial lithium production relies on mineral ore sources such as spodumene, petalite, and lepidolite. This study provides an economic comparison of two processes for the extraction of lithium from zinnwaldite concentrate, a lithium mineral that can be found along the Czech/German border at Cínovec/Zinnwald. In contrast to the state‐of‐the‐art lithium extraction from siliceous ores, which is a hydrometallurgical extraction process with sulfuric acid, the novel direct‐carbonation process is based on digestion using supercritical carbon dioxide. An assessment of the capital and operating expenditures was also carried out.     

Unusual Lipid A from a Cold‐Adapted Bacterium: Detailed Structural Characterization

Colwellia psychrerythraea 34H is a Gram‐negative cold‐adapted microorganism that adopts many strategies to cope with the limitations associated with the low temperatures of its habitat. In this study, we report the complete characterization of the lipid A moiety from the lipopolysaccharide of Colwellia. Lipid A and its partially deacylated derivative were completely characterized by high‐resolution mass spectrometry, NMR spectroscopy, and chemical analysis. An unusual structure with a 3‐hydroxy unsaturated tetradecenoic acid as a component of the primary acylation pattern was identified. In addition, the presence of a partially acylated phosphoglycerol moiety on the secondary acylation site at the 3‐position of the reducing 2‐amino‐2‐deoxyglucopyranose unit caused tremendous natural heterogeneity in the structure of lipid A. Biological‐activity assays indicated that C. psychrerythraea 34H lipid A did not show an agonistic or antagonistic effect upon testing in human macrophages.     

A Control‐oriented Dynamic Model Adapted to Variant Steam‐to‐carbon Ratios for an SOFC with Exhaust Fuel Recirculation

The steam‐to‐carbon ratio (S/C) is a typical disturbance parameter in the operation of solid oxide fuel cell (SOFC) power generation system. A planar SOFC with a pre‐reformer and exhaust fuel recirculation system is investigated in this work. A lumped, nonlinear dynamic model is developed for the SOFC with consideration both of the spatial effect and the variant S/Cs. The dynamic model is deduced based on a fitting function so‐called Exponential Association Function, which is employed to describe the spatial distribution of state variables in SOFC. Three parameters of the fitting function are identified to integrate the spatial effect and S/C effect in the model. The parameters of Exponential Association Function are determined by function fitting on three‐dimensional numerical data at the sample operation points. Carbon formation activity is analysed using the simulation results and thermodynamic data. Dynamic simulation is implemented with the help of software MATLAB/SIMULINK. The results show that the developed model has good performance in predicting the responses of the state variables and catching the changes of S/C.     

Preparation of an ultraviolet‐curable water‐borne poly(urethane acrylate)/silica dispersion and properties of its hybrid film

An organic–inorganic hybrid material was prepared through the addition of nanometer fumed silica partly modified by dimethyl dichlorosilane into a water‐borne poly(urethane acrylate) (PUA) anionomer. A PUA/silica hybrid film was made via ultraviolet curing. The mechanical properties of the hybrid film were studied. The tensile strength, elongation at break, pendulum hardness and the glass‐transition temperature of the hybrid material increased with increasing content of silica. Scanning electron microscopy showed an asymmetrical distribution of modified silica in PUA. Atomic force microscopy demonstrated that silica particles could make the surface of the film smooth. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1347–1352, 2004     

Numerical investigation of gas mixing in gas‐solid fluidized beds

Gas mixing in a tall narrow fluidized bed operated in the slugging fluidization regime is simulated with the aid of computational fluid dynamics. In the first part, a parametric study is conducted to investigate the influence of various parameters on the gas mixing. Among the parameters studied, the specularity coefficient for the partial‐slip solid‐phase wall boundary condition had the most significant effect on gas mixing. It was found that the solid‐phase wall boundary condition needs to be specified with great care when gas mixing is modeled, with free slip, partial slip and no‐slip wall boundary conditions giving substantial differences in the extent of gas back mixing. Axial and radial tracer concentration profiles for different operating conditions are generally in good agreement with experimental data from the literature. Detailed analyses of tracer back mixing are carried out in the second part. Two parameters, the tracer backflow fraction and overall gas backflow fraction, in addition to axial profiles of cross‐sectional averaged tracer concentrations, are evaluated for different flow conditions. Qualitative trends are consistent with reported experimental findings. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Polyurethane ionomer dispersions from a blocked aromatic‐diisocyanate prepolymer

Aqueous anionic blocked aromatic polyurethane prepolymers were synthesized by a prepolymer mixing process and their dispersions were obtained by adding water to the blocked prepolymer solutions. A series of prepolymers were prepared by using toluene 2,4‐diisocyanate, 4,4′‐diphenylmethane diisocyanate, polytetramethylene glycol, dimethylol propionic acid, methyl ethyl ketoxime and ε‐caprolactam. The aqueous dispersions were characterized by Fourier‐transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. The particle sizes, viscosities, pH and storage stabilities of the dispersions were studied and compared. Some mechanical properties of the cast films obtained from the aqueous dispersions and the adhesive properties of the dispersions were also evaluated. Copyright © 2004 Society of Chemical Industry     

Syringolin A Selectively Labels the 20 S Proteasome in Murine EL4 and Wild‐Type and Bortezomib‐Adapted Leukaemic Cell Lines

The natural product syringolin A (SylA) is a potent proteasome inhibitor with promising anticancer activities. To further investigate its potential as a lead structure, selectivity profiling with cell lysates was performed. At therapeutic concentrations, a rhodamine‐tagged SylA derivative selectively bound to the 20 S proteasome active sites without detectable off‐target labelling. Additional profiling with lysates of wild‐type and bortezomib‐adapted leukaemic cell lines demonstrated the retention of this proteasome target and subsite selectivity as well as potency even in clinically relevant cell lines. Our studies, therefore, propose that further development of SylA might indeed result in an improved small molecule for the treatment of leukaemia.