Scale-Up for End Effects and Phase Distribution

Packed Towers ◽  
2005 ◽  
pp. 191-212
Keyword(s):  
Phase Distribution ◽  
Scale Up ◽  
End Effects

scholarly journals Cell Model for the Scale-up of Fluid Dynamics and Mass Transfer in Random Packed Columns Affected by Maldistribution

2021 ◽  
Author(s):  
Jost Brinkmann ◽  
Amelie Merkel ◽  
Dominik Plate ◽  
Marcus Gruenewald
Keyword(s):  
Fluid Dynamics ◽  
Mass Transfer ◽  
Phase Distribution ◽  
Cell Model ◽  
Scale Up ◽  
Computational Effort ◽  
Fluid Distribution ◽  
Liquid Distribution ◽  
Correlation Distribution ◽  
Distribution Parameters

The characterization of fluid dynamics and mass transfer is often influenced by phase maldistribution. An existing cell model approach for fluid distribution is extended for gas distribution and mass transfer. The model differentiates wall and bulk zones, allowing a detailed evaluation of local fluid dynamics and mass transfer, which is based on a state-of-the-art literature correlation. Distribution parameters are determined experimentally. The model allows scale-up by considering the phase distribution at constant computational effort. A scale-up strategy to adapt the distribution parameters to different geometries is presented. Results for fluid dynamics and liquid distribution are in good agreement with experimental data of columns with diameters of 0.288, 0.5 and 0.6 m. Mass transfer is in good qualitative agreement with own experiments in a 0.288 diameter column. While maldistribution consequently reduces the gas side mass transfer, the reduced liquid bulk flow weakens the effect of liquid side mass transfer.

scholarly journals Fabrication Process and Product Quality Improvements in Advanced Gas Reactor UCO Kernels

2008 ◽  
Author(s):  
Charles M. Barnes ◽  
W. C. Richardson ◽  
DeWayne Husser ◽  
Matthias Ebner
Keyword(s):  
High Temperature ◽  
Phase Distribution ◽  
National Laboratory ◽  
Scale Up ◽  
Fabrication Process ◽  
Alternative Methods ◽  
Test Program ◽  
Forming Process ◽  
Oak Ridge ◽  
Enriched Uranium

A major element of the Next Generation Nuclear Plant (NGNP)/Advanced Gas Reactor (AGR) Fuel Development and Qualification Program is developing fuel fabrication processes to produce high quality uranium-containing fuel kernels, TRISO-coated particles and fuel compacts needed for planned irradiation tests. The goals of the program also include developing the fabrication technology to mass produce this fuel at low cost. Kernels for the first AGR test, AGR-1, consisted of uranium oxycarbide (UCO) microspheres that were produced by an internal gelation process followed by high temperature steps to convert the UO3 + C “green” microspheres to UO2 + UCx. The high temperature steps also densified the kernels. Babcock and Wilcox (B&W) fabricated UCO kernels in their Lynchburg facility for the AGR-1 irradiation experiment, which went into the Advanced Test Reactor (ATR) at Idaho National Laboratory in December 2006. An evaluation of the kernel process prior and after these kernels were produced led to several recommendations to improve the fabrication process. These recommendations included testing alternative methods of dispersing carbon during broth preparation, evaluating the method of broth mixing, optimizing the broth chemistry, optimizing sintering conditions, and demonstrating fabrication of larger diameter UCO kernels needed for the second AGR irradiation test, AGR-2. Based on these recommendations and requirements, a test program was defined and performed. Certain portions of the test program were performed by Oak Ridge National Laboratory (ORNL), while tests at larger scale were performed by B&W. The tests at B&W have demonstrated improvements in both kernel properties and process operation. Changes in the form of carbon black used and the method of mixing the carbon prior to forming kernels led to improvements in the phase distribution in the sintered kernels, greater consistency in kernel properties, a reduction in forming run time, and simplifications to the forming process. Process parameter variation tests in both forming and sintering steps led to an increased understanding of the acceptable ranges for process parameters and additional reduction in required operating times. Another result of this test program was to double the kernel production rate. Following the development tests, approximately 40 kg of natural uranium UCO kernels have been produced for use in coater scale up tests, and approximately 10 kg of low enriched uranium UCO kernels for use in the AGR-2 experiment.

NiAl precipitation in Fe-12w/o Cr-5w/o Ni-4w/o Al

1983 ◽  
Vol 41 ◽  
pp. 202-203
Author(s):  
L.E. Murr ◽  
J.S. Dunning ◽  
S. Shankar
Keyword(s):  
Solid Solution ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Alloy Composition ◽  
Chromium Content ◽  
Scale Up ◽  
Optical Metallography ◽  
Property Evaluation ◽  
310 Stainless Steel ◽  
Microstructural Studies

Aluminum additions to conventional 18Cr-8Ni austenitic stainless steel compositions impart excellent resistance to high sulfur environments. However, problems are typically encountered with aluminum additions above about 1% due to embrittlement caused by aluminum in solid solution and the precipitation of NiAl. Consequently, little use has been made of aluminum alloy additions to stainless steels for use in sulfur or H2S environments in the chemical industry, energy conversion or generation, and mineral processing, for example.A research program at the Albany Research Center has concentrated on the development of a wrought alloy composition with as low a chromium content as possible, with the idea of developing a low-chromium substitute for 310 stainless steel (25Cr-20Ni) which is often used in high-sulfur environments. On the basis of workability and microstructural studies involving optical metallography on 100g button ingots soaked at 700°C and air-cooled, a low-alloy composition Fe-12Cr-5Ni-4Al (in wt %) was selected for scale up and property evaluation.

Digital phase analysis in interference electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 842-843
Author(s):  
S. Hasegawa ◽  
T. Kawasaki ◽  
J. Endo ◽  
M. Futamoto ◽  
A. Tonomura
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Phase Distribution ◽  
Magnetic Recording Media ◽  
Electron Wave ◽  
Vector Potentials ◽  
Weak Magnetic Fields ◽  
Leakage Magnetic Field ◽  
Optical Reconstruction ◽  
Processing Techniques

Interference electron microscopy enables us to record the phase distribution of an electron wave on a hologram. The distribution is visualized as a fringe pattern in a micrograph by optical reconstruction. The phase is affected by electromagnetic potentials; scalar and vector potentials. Therefore, the electric and magnetic field can be reduced from the recorded phase. This study analyzes a leakage magnetic field from CoCr perpendicular magnetic recording media. Since one contour fringe interval corresponds to a magnetic flux of Φo(=h/e=4x10-15Wb), we can quantitatively measure the field by counting the number of finges. Moreover, by using phase-difference amplification techniques, the sensitivity for magnetic field detection can be improved by a factor of 30, which allows the drawing of a Φo/30 fringe. This sensitivity, however, is insufficient for quantitative analysis of very weak magnetic fields such as high-density magnetic recordings. For this reason we have adopted “fringe scanning interferometry” using digital image processing techniques at the optical reconstruction stage. This method enables us to obtain subfringe information recorded in the interference pattern.

Application of electron holography to material science studies on magnetic domain states of small particles

1993 ◽  
Vol 51 ◽  
pp. 1028-1029
Author(s):  
T. Hirayama ◽  
Q. Ru ◽  
T. Tanji ◽  
A. Tonomura
Keyword(s):  
Magnetic Field ◽  
Material Science ◽  
Science Studies ◽  
Phase Distribution ◽  
Carbon Film ◽  
Objective Lens ◽  
Electron Holography ◽  
Transform Method ◽  
Transmission Electron ◽  
Thin Carbon

The observation of small magnetic materials is one of the most important applications of electron holography to material science, because interferometry by means of electron holography can directly visualize magnetic flux lines in a very small area. To observe magnetic structures by transmission electron microscopy it is important to control the magnetic field applied to the specimen in order to prevent it from changing its magnetic state. The easiest method is tuming off the objective lens current and focusing with the first intermediate lens. The other method is using a low magnetic-field lens, where the specimen is set above the lens gap.Figure 1 shows an interference micrograph of an isolated particle of barium ferrite on a thin carbon film observed from approximately [111]. A hologram of this particle was recorded by the transmission electron microscope, Hitachi HF-2000, equipped with an electron biprism. The phase distribution of the object electron wave was reconstructed digitally by the Fourier transform method and converted to the interference micrograph Fig 1.

Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

1990 ◽  
Vol 48 (4) ◽  
pp. 990-991
Author(s):  
Mahesh Chandramouli
Keyword(s):  
Electron Microscope ◽  
Liquid Phase ◽  
Permanent Magnets ◽  
Phase Distribution ◽  
Energy Dispersive Spectrometer ◽  
Nucleation And Growth ◽  
Liquid Phase Sintering ◽  
Domain Wall Energy ◽  
Oxide Phases ◽  
Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

Scale-up of polyphenolic isolation by HPLC from Uncaria guianensis leaves by applying chromatographic models

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
RS Barboza ◽  
BR Rocha ◽  
AC Siani ◽  
LMM Valente ◽  
JL Mazzei
Keyword(s):  
Scale Up
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