Particle exchange in horizontal two-compartment fluidized beds – CFD simulation and experimental validation

A series of ideally mixed fluidized beds is used to obtain a narrow product size distribution in industrial-scale applications. Thereby, the fluidized bed compartments or stages are divided from each other by weirs with defined openings (slots) for particle exchange. The knowledge of particle exchange streams and residence times in different compartments, respectively, is crucial for the process design and optimization of such processes. This particle exchange behavior between different compartments in 3D-fluidized bed systems cannot be easily evaluated by experiments.Hence, a CFD multiphase model is used here and applied to a horizontal two-compartment batch fluidized bed apparatus to obtain particle exchange streams as a function of process parameters, e.g. slot height and bed mass. Good comparison of numerical and experimental results shows that this model can reasonably predict the particle exchange in two-compartment fluidized bed processes.On the basis of this work, the validated and predictive multiphase model can be applied to continuous horizontal multi-compartment fluidized beds as a future perspective to identify best-case process parameters, e.g. optimal slot height.     

METHODS FOR PROCESSING EXPERIMENTAL DRYING KINETICS DATA

This paper provides a review of methods for processing the data obtained from drying kinetics rigs and pilot-plant trials. Different methods for fitting and smoothing drying curves are compared, aiming to generate curves that are usable in industrial design without losing vital information by oversmoothing. Generally, plots of drying rate need more smoothing than moisture content data. Special care is needed at low drying rates and moisture contents. It is shown that some popular methods of processing data, including use of smoothing programs or fitting to equations, may generate drying curves which are seriously in error. Recommendations are made for reliable methods of processing data; cubic splines have been found to be effective for moisture-time curves. It is important to retain the original raw experimental data as a cross-check, as smoothing can conceal valuable information.     

Volume Image Analysis of Ceramic Sponges

The three‐dimensional structure of monolithic networks such as ceramic sponges and their geometrical dimensions are part of the fundamentals necessary for investigation in most possible applications in chemical engineering. A volume imaging method must be applied to determine this structure and to measure features such as the specific surface area and the pore diameter. Magnetic Resonance Imaging was chosen for such measurements in this study. The analysis of volume images is performed with various methods based on different principles, which are compared with each other as well as with data generated by conventional techniques and from literature models.     

Continuous polymerization of methyl methacrylate in a taylor‐couette reactor. II. influence of fluid dynamics on polymer properties

In this work, the free radical continuous polymerization of methyl methacrylate (MMA) with the solvent xylene and 2,2‐Azoisobutyronitrile (AIBN) as initiator was studied in a laboratory Taylor‐Couette reactor. It was found that the property of the polymerized product (molecular weight distribution) is affected by the fluid dynamic conditions (mean residence time, rotational speed, diameter of the inner cylinder, and gap width). The weight average molecular weight decreases with an increase of the mean residence time, is strongly dependent on the geometry of the reactor, and was found to be independent on the shear rate in the gap. The width of the molecular weight distribution decreases weakly with increasing residence time, increases with increasing shear rate, and weakly depends on the diameter of the inner cylinder. A correlation was developed to describe the weight‐average molecular weight as a function of the Taylor number and the Damköhler number. This correlation is dimensionless and may be used for scaling‐up purposes. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Monoclonal antibody Cat-301 selectively identifies a subset of nuclei in the cat's somatosensory thalamus

Recently it has been demonstrated that the monoclonal antibody Cat-301 is capable of identifying functionally related neurons in the mammalian visual thalamus. We have examined the possibility that this antibody might display a similar capacity in nonvisual thalamic areas. We demonstrate that in the cat's somatosensory thalamus the distribution of Cat-301-positive cells and neuropil is restricted to a subset of nuclei. These include the ventroposterior medial, ventroposterior lateral, and ventroposterior inferior nuclei. Staining with Cat-301 provides a clear visualisation of the entire somatotopic map within these nuclei. The somatosensory sector of the thalamic reticular nucleus and the perireticular nucleus, which may have a somatosensory sector, are also Cat-301-positive. In contrast, cells that do not express the Cat-301 antigen are located in the ventroposterior oralis nucleus, the ventroposterior shell region, the medial and lateral divisions of the posterior nuclear group, and the inner small cell region adjacent to the thalamic reticular nucleus. In comparison with previous physiological studies, cells that express the Cat-301 antigen most likely represent subpopulations in only a few of the somatic submodality-specific groups. These include cells in the small-field and Pacinian cutaneous-responsive groups, excluding cells in the wide-field cutaneous-, muscle-, joint-, and noxious-responsive groups. Taken together these findings indicate that monoclonal antibody Cat-301 is capable of selectively identifying neurons with distinct functional properties in the mammalian somatosensory thalamus.     

Transfer factor therapy in a patient with anergic pulmonary tuberculosis

Report on a patient suffering from severe, relapsing pulmonary tuberculosis showing progressive clinical deterioration accompanied by the appearance of cutaneous anergy to tuberculin. In addition, the sputum cultures showed growth of Mycobacterium intracellulare. During therapy with transferfactorZurich there was a slow but impressive clinical improvement, the skin reactivity to tuberculin was reconstitued and the sputum cultures became negative. The radiological findings remained unchanged.     

Frequency-dependent dispersion of high-frequency ground penetrating radar wave in concrete

This paper studies the dielectric dispersion of high frequency radar wave in concrete in early-aged and hardened concrete specimens. Frequency-dependent spectra of phase velocity v(ω) were measured to deduce the spectra of real part of dielectric permittivity ε′(ω). The dispersion was measured by three high nominal ground penetrating radar frequencies (1.5, 1.6 and 2.6 GHz), experimenting on two steel bars with concrete cover 50 and 100 mm. It was found that v(ω) and ε′(ω) dispersed at lower frequency, but became stable at high frequency regions, which agrees with the classical GPR plateau. The same frequency components at different nominal antenna frequencies show a close range of v(ω) and ε′(ω) in concrete of different ages. The results in this paper warrant further investigation of using GPR wave to study material properties.