Drop‐size distributions and spatial distributions in an annular centrifugal contactor

Annular centrifugal contactors were developed as single, compact units utilized to transfer desired species between immiscible fluid phases. Critical to understanding the mass‐transfer characteristics in the annular mixing region is a clear picture of the distribution of droplet sizes of the fluids involved. To date, very little experimental data appears in the literature. We fill that void by using laser fluorescence and optical methods to directly observe and measure drop‐size distributions for a silicone oil/water system in a centrifugal contactor. The shape and characteristics of the log‐normal distributions, including the Sauter mean diameter and distribution means, are elucidated in terms of rotor speed and organic phase fraction. The size distribution of entrained air bubbles is also examined. The results presented here will be invaluable in validating and expanding the predictive capacity of the many models that have been developed to describe the flow within these devices. Published 2013 American Institute of Chemical Engineers AIChE J, 59: 2219–2226, 2013     

Verfahren zur Verarbeitung von tierischen Rohfetten unter besonderer Berücksichtigung zentrifugaler Klär- und Trennvorgänge

Methods for Processing Animal Raw Fats with Special Consideration of Centrifugal Clarifying and Separating Processes Modern methods for processing animal raw fats are characterized by extensive application of centrifugal clarifying and separating techniques. The physical principles of such techniques as well as the design of the centrifugal equipment used, incorporating the latest developments, are dealt with in the first part of this publication. Optimum operating efficiency of centrifugal decanters functioning as pre-clarifiers is demonstrated by describing their operating principles, design, and distinguishing engineering features. For the separation of liquid mixtures and for fine clarification (?polishing”?), self-cleaning centrifugal separators are provided. Based on the constructional features of these separators, various possibilities of sediment discharge and various control systems are explained. The treatment of animal raw fat and the proper process technology are detailed in the second part of this publication. Continuous wet rendering processes are widely used in practice nowadays. Critical comments are given on the advantages of these processes as compared with the dry rendering methods. In conclusion, reference is made to environmental protection. Measures to be taken against air and water pollution are given special attention.     

On near‐wall jets in a disc‐like gas vortex unit

To clarify the three‐dimensional (3D) structure of near‐wall jets observed in disc‐like gas vortex units (GVUs), experimental and numerical studies are performed. The experimental results are obtained using stereoscopic particle image velocimetry (PIV), laser doppler anemometry, pressure probes and surface oil flow visualization techniques. The first three techniques have been used to investigate the bulk flow hydrodynamics of the vortex unit. Surface oil flow visualization is adopted to visualize streamlines near the end‐walls of the vortex unit. The surface streamlines help to determine the azimuthal and radial velocity components of the radial near‐wall jets. Simulations of the vortex unit using FLUENT^® v.14a are simultaneously performed, computationally resolving the near‐wall jet regions in the axial direction. The simulation results together with the surface oil flow visualization establish the 3D structure of the near‐wall jets in GVUs for the first time in literature. It is also conjectured that the near‐wall jets develop due to the combined effect of bulk flow acceleration and swirl. The centrifugal force diminishes in the vicinity of the end‐walls. The radially inward pressure gradient in these regions, no longer balanced by the centrifugal force, pushes gas radially inward thus developing the near‐wall jets. © 2016 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 63: 1740–1756, 2017     

Practical Experience in Design and Operation of Liquid‐Liquid Extraction Processes

Liquid‐liquid (L/L) extraction is a standard unit operation in the phenol‐acetone process. Special applications are the extraction of phenol from process water and the removal of phenol from recycle cumene. Besides the standard equipment such as static mixers and horizontal settlers, centrifugal pumps are used for mixing and vertical settlers are operated for phase separation. This article covers some practical experience in design and operation with focus on using centrifugal pumps, maintain mass transfer in pipes and the design of vertical settlers. Gaps in knowledge about various phenomena such as the mass transfer in turbulent L/L pipe flow are pointed out.     

Hydrodynamics and Transport Processes during Centrifugal Short‐Path Distillation

To simulate the centrifugal short‐path distillation process, both two phases and interfacial transport are taken into account simultaneously for the first time. A new computational fluid dynamics model based on the volume‐of‐fluid and species transport methods is built up to analyze the detailed flow and transfer characteristics. A binary system with dibutyl phthalate‐dibutyl sebacate (DBP‐DBS) is used as an example for the investigation with both numerical and experimental methods. The residence time and the effects of operating parameters such as evaporator temperature and feed flow rate are explored comparatively. The simulation result for the liquid‐film thickness shows a satisfactory agreement with literature data. On the basis of the simulation results, we may also obtain detailed characteristics of the heat and mass transfer such as gradients in temperature and concentration and the liquid overall mass transfer coefficient.     

Die Bedeutung des Zerstäubungsprozesses für sprühgetrocknetes Milchpulver

Significance of the Spraying Process in Spray-Dried Milk Powder The spraying process in a spray-drying plant is of great significance for the manufactured milk powder. Using a pressure nozzle and a specially constructed spraying wheel one can obtain skimmed milk powder having high specific gravity and low air-content. As compared to normal powder obtained by centrifugal spraying this product possesses better instant properties and low packing volume.     

Stability and spinnability of modified melamine–formaldehyde resin solution for centrifugal spinning

Melamine microfibers were first prepared by centrifugal spinning. The stability and spinnability of a melamine–formaldehyde (MF) resin solution were improved as expected by adding various modifier combinations. Considering the storage stability of solutions characterized by visual inspection, turbidity tests, and viscosity measurements and combined with the fiber morphology, the optimal modifier combination was obtained. The spun fibers manifested a good morphology and thermal stability as measured by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover, microfibers prepared by three spinning methods (centrifugal spinning, electrospinning, and centrifugal electrostatic spinning) were compared to choose the suitable spinning method for different fields in the future. This work provides systematic and scientific guidance on the synthesis of MF resin solutions and rapid mass production of melamine microfibers and also demonstrates that centrifugal spinning of melamine microfiber is a promising candidate for flame retardance and CO₂ adsorption at elevated temperature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46072.     

Hermetische Kreiselpumpen für hochwarme bis tiefkalte Kreisläufe

Hermetically Closed Centrifugal Pumps for Extremely Hot and Cold Circulations Economical, reliable and automatic processing with a high degree of environmental safety are the criteria that must be fulfilled by plant manufacturers. Such conditions can be realised by switching over from ”?open”? to ”?closed”? processing. Hermetically closed centrifugal pumps enable the solution of difficult problems, such as the transport of fatty acids, heating oils, acids, alkalis, toxic substances, liquefied gases, and cooling agents. The construction and mode of function of hermetically closed centrifugal pumps and their possible applications are discussed.     

Flow dynamics in Taylor–Couette flow reactor with axial distribution of temperature

In this study, the flow dynamics of a Taylor–Couette flow with an axial distribution of temperature was experimentally investigated. The flow can be classified into three patterns based on the balance between the centrifugal force and the buoyancy. If the buoyancy is dominant, global heat convection is observed instead of Taylor vortices (Case I). When the buoyancy is comparable to the centrifugal force, the Taylor vortices and global heat convection appear alternately (Case II). If the centrifugal force is sufficiently high to suppress the buoyancy, stable Taylor vortices are observed (Case III). The characteristics of the mixing/diffusion are investigated by conducting a decolorization experiment on a passive tracer. In Case II, the tracer is rapidly decolorized in the presence of the global heat convection instead of the Taylor vortices. This result implies that the interaction between the centrifugal force and the buoyancy would induce an anomalous transport. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1075–1082, 2018     

On the efficiency of a centrifugal fan wet scrubber

An inertial theoretical model is proposed to predict the capture of aerosol particles by accelerating liquid droplets in a centrifugal fan scrubber. The results are in good agreement with literature experimental data for micron and large submicron size particles. The theory tends to underestimate the scrubber performance for submicron size particles of less than 0.3 μm in diameter. The discrepancy may be due to the lack of a reliable expression predicting the diffusion deposition of aerosol particles on an isolated liquid droplet. The effects of variables such as fan speed, sizes of liquid droplets and particles, gas and liquid flow rates predicted by the theory are discussed and agree with literature observation.     

Avocado oil production and chemical characteristics

Centrifugal force separation is a relatively new industrial process for extracting avocado oil. This study examined the influences of temperature, pH and NaCl concentration on oil extraction efficiency by centrifugal processing. Optimal separation conditions occurred at 75 C, with a pH of 5.5 and NaCl concentration of 5%. Differences in chemical characteristics exist between avocado oils produced by industrial processes and those oils that were produced in the laboratory by organic solvent extraction. The highest amount of chlorophyll, 192.9 ppm, was obtained by ethanolic extraction in the laboratory. Unsaponifiables content reached 1.95% in industrial oil produced by organic solvent extraction. The highest acid value, 8.35, was obtained from industrial oil produced by centrifugal separation. Hydroxyl values in our oils were found to be 2–3 times higher than those reported in the literature.     

The electrodeposition of precious metals; a review of the fundamental electrochemistry

A literature survey of the electrodeposition of the precious metals is reported. The fundamental aspects of the kinetics are assessed in the light of recent progress in metal deposition studies.     

某炼化污水场污泥干燥-焚烧-体化处理工艺设计

某炼化污水场产生的污泥仅进行了离心脱水处理,污泥量大,外委处置费用高,因此需进行污泥减量化处理。经过实地调查、现场试验、理论研究并结合以往的工程案例,设计了新型的污泥干燥-焚烧一体化处理工艺,针对此处理技术的工程设计进行了介绍。     

Ketofettsäure-Derivate – Ein einfaches Verfahren zu ihrer Herstellung

Keto Fatty Acids – A Simple Procedure for their Preparation Derivatives of keto fatty acids are trace components in many of the naturally occurring oils and fats. After a survey of preparation procedures described in the literature, a simple possibility for the preparation of keto fatty acid derivatives by alkali- or alkaline earth iodides catalyzed rearrangement of epoxidized fatty acid derivatives will be presented. Tests of these compounds as additives in PVC processing showed positive results.     

A NOTE ON WAVE MOTIONS WITH A CYLINDRICAL FLUID INTERFACE STABILIZED BY ROTATION

The Rayleigh's capillary instability of a cylindrical fluid interface can be suppressed by the centrifugal force due to coaxial rotation when the outer fluid is heavier than the inner one. Thus, wave motions on the rotationally stabilized cylindrical interfaces can occur in natural and technological processes, notwithstanding the lack of coherent treatment in the literature. This work provides a supplementary linear analysis of various wave motions in a three-dimensional framework for two-phase inviscid fluid systems with cylindrical interfaces stabilized by rotation. Many previous results found in the literature are recast in a general from. With gravity acting perpendicularly to the rotation axis, the interface disturbance is considered as an externally forced wave motion. The condition for the stability of the gravity-induced interface displacement in a two-phase rotating system is found to be exactly the same as that for the one-phase case such as an air column in a rotating liquid.     

螺旋片导流式气液分离器的数值模拟与试验研究

The gas/liquid spiral separator, a key component in the compressed air system, was used to remove liquid and oil from gas stream by centrifugal and gravitational forces. To optimize the design of the separator, the relationship between the performance and structural parameters of separators is studied. Computational fluid dynamics （CFD） method is employed to simulate the flow fields and calculate the pressure drop and separation efficiency of air-liquid spiral separators with different structural parameters. The RSM （Reynolds stress model） turbulence model is used to analyze the highly swirling flow fields while the stochastic trajectory model is used to simulate the traces of liquid droplets in the flow field. A simplified calculation formula of pressure drop in spiral structures is obtained by modifying Darcy＇s equation and verified by experiment.     

Rotierende Verdrängerpumpen zur Förderung von Flüssigkeiten,breiigen und pastösen Massen

Rotating Positive Displacement Pump for Transport of Liquids, Slurries, and Pasty Masses As regards medium transport, pipe friction losses and the efficiency of the pump are the determinant factors for the motor power provided. The fundamental differences between a centrifugal pump and a positive displacement pump is made clear. Design and specific qualities of one-, two- and three spindle pumps, which are classified as rotary displacement pumps, are described. A novel classification of the fluids, related to one-, two- and three spindle pumps and a table of the application limits make it easy to select the most suitable pump.     

Fabrication of Functionally Graded SiO2‐Mo Material by Centrifugation and Floc‐Casting of Highly Concentrated Slurry

To fabricate functionally graded materials, a highly concentrated slurry of SiO₂‐Mo system was prepared and centrifugal force was applied in an attempt to achieve a graded composition. Subsequently, we formed a homogeneous green body with compositional gradation by floc‐casting at 80°C, which was then fired at 1750°C for 10 min in Ar. The sintered body had compositional ratios of SiO₂ and Mo as well as electrical conductivities that changed gradually along the direction of centrifugal force. The results demonstrate that centrifugation and control of slurry characteristics such as flocculation are effective in fabricating functionally graded SiO₂‐Mo materials.