Size distribution and density

AN particle shape, size distribution and density have a significant effect on the mixing and loading characteristics of molten Minol II. The product made with grained AN was best with respect to ease of mixing, smooth consistency, uniform viscosity, pourability and cast density (Ref 48)... 

W. Machtle, Analysis of polymer dispersions with an eight cell-AUC-multiplexer high resolution particle size distribution and density gradient techniques (in Ref. [77]). 

Example A. Suppose it was desired to design a cyclone to collect all particles larger than 97 microns and release no more than 60 lbs/hr from a 6328 ACFM gas stream bearing 80 grains of solids per cubic foot of gas. The particle size distribution and density of the solids is given in Fig. 18 the gas has a density of 0.1 lbs/ft3 and a viscosity of 0.02 centipoise. The pressure drop across the cyclone is not to exceed 10" H20. Note from Fig. 1 of the text that 100% collection efficiency of 97 micron particles would require a Dth of 9.7 microns which would be collected at an average 50%... 

The most important characteristics of the final formulation to be compacted are particle size and particle size distribution, density and/or porosity, powder flow, cohesiveness, and lubrication. Particle size, particle size distribution, and density and porosity of the formula will not be addressed here because they are the result of other operations in the scale-up sequence, such as granulation and milling. They should be evaluated as part of those specific operations. It should be noted, however, that the influence of particle size on powder flow and, therefore, on uniform die fill is very important to the compaction operation, but is not a result of it. The one consideration to keep in mind during scale-up is the speed of the press, which will directly affect the time available for the die filling to occur. This is an important parameter to observe carefully. 

Granulation is a process of agglomeration where signiLcant particle growth is accomplished in a powder blend by the addition of binder solution. The unit operation is intended to ensure content uniformity, improve blend Low, provide narrow particle size distribution, and density the material. 

Duration of exposure to the wind Size of the particle bed Size distribution and density of the particles Value. de Xst el 7b+... 

Evaluation of Granulation Particle Size Distribution and Density... 

Generally, when developing a direct compression formulation, efforts to match particle size distribution and density of drug substance to the major excipients help minimize segregation. Meanwhile, the particle size distribution should be relatively narrow (100 im range) to ensure a satisfactory flow for the blend. The commonly used excipients for preparing direct compression blends can be categorized by the... 

Ingredient Segregation Avoided Powders such as hypromellose and titanium dioxide exhibit dramatically different particle size distribution and density. Such particle heterogeneity may result in constituent segregation inducing film imperfections or color deviations on tablets. 

Coghill, P.J. and Sowerby, B.D. (1995), A method and apparatus for the determination of the particle size distribution and density of fine particles in slurries. International Patent Application No PCT/AU96/00362, 555... 

These are, in turn, controlled by the size distribution and density of the coal particles. To maintain homogenous flow, which is necessary to minimize wear of the pipeline, a coal slurry should have the following properties, assuming a coal specific gravity of 1.4 ... 

The size distribution and density of inclusion bodies have been studied only for two proteins, calf prochymosin and y-interferon (64). The mean particle sizes of y-interferon and prochymosin inclusion bodies were O.Slgm with a standard deviation of 0.17gm and 1.28gm with a standard deviation of 0.46gm, respectively. The buoyant density of the y-interferon and prochymosin inclusion bodies was proportional to the density of the suspension medium indicating a relatively high voidage within the particles. The void fraction (=void volume/total volume) was 70% for y-interferon and 85% for prochymosin. 

Membranes are characterized by structure and function that is, vfaat they are and how they perform. The most significant primary structural properties of a membrane are its chemical nature including the presence of charged species at the molecular level, its microcrystalline structure at the microcrystalline level, and on the collodial level its pore statistics such as pore size distribution and density, and degree of asymmetry (11) (12). 

The pores are formed from bubbles during some of the typical manufacturing processes of polymer materials. The size distribution and density distribution of both are important to performance during the polishing process. Figure 6.17 shows two scanning electron micrographs of a polymer with such pore structures the first is the sidewall cross-section of the material, and the second is the top surface after some use. 

The initial and perhaps most critical design assumption is that both the MgO and the fly ash, which are carried out of the calciner and into the MgO product cyclone, have the same particle size distribution and density. This design (i.e., no possibility of physical separation of MgO and fly ash) is a conservative design assumption and adds complexity to the FGD process. It results in the need to recirculate large quantities of the MgO/fly ash mixture through the spray dryer and the calciner. In order to keep the MgO/ash recycle streams to a reasonable size, the mechanical collectors in the main flue gas ducts upstream from the SO2 absorber, which were used in the initial design because they are relatively inexpensive but yet remove only 80% of the fly ash, had to be replaced with the 95% efficient ESP mentioned earlier. 

The concepts of limited sediment supply to rivers and an upper limit to the capacity of a particular flow rate to transport sediment of a particular particle size distribution and density explain the phenomenon of hysteresis, where sediment concentration for a given flow rate differs on the rising and falling limbs of a flow event. There is thus no simple relationship between flow and concentration, and a sediment rating curve will inherently have wide error bars. 

Controlled size, size distribution, and density facilitating good mixing with other powders, without fine particles (source for dust)... 

The effectiveness of a membrane is often determined by how well it performs the function for which it is developed. However, any membrane can be improved if the structure which results from its preparation is known. The structure can suggest changes in the mode of preparation or conditioning that enhance the overall quality. Some physical techniques used to characterize the size, shape, size distribution, and density of pores and the molecular structure of the membrane surface follow. 

An examination of technical literature and trade publications indicates that a wide variety of instmments are commercially available for PSD analysis.The classical methods are based on either electrical properties (e.g., the Coulter Counter principle) or optical properties (e.g., laser scattering) of the analyte. However, none of these techniques are separation methods. Because particulate dispersions are often highly complex in terms of the polydispersity index, multimodal size distribution, and density, it is hardly possible, without the use of separative methods, to obtain an accurate determination of their... 

Some 30 years ago the analytical ultracentrifuge played an important part in characterising weight-average MWD, size distribution, and density distribution in polymers. This technique was displaced by SEC. However, with improvements in instrumentation, ultracentrifuge methods are to some extent making a comeback. 

If, however, the mass efficiency is found for every particle size x, a curve referred to as the gravimetric grade efficiency function G(a ) is obtained which is normally independent of the solids size distribution and density and is constant for a particular set of operating conditions, e.g. fluid viscosity, flow rate and often also solids concentration. It is necessary, however, that the chosen characteristic particle size is a decisive factor in the principle of separation used in the equipment. 

Many of the required granule product attributes are directly related to the size, size distribution, and density of the granule product. These granule properties develop as a result of three classes of rate process in the granulator (Fig. 1) ... 

There are a variety of designs [23] of vacuum filter, the selection of which depend strongly on the particle size distribution and density of the suspended solids in the feed slurry. The main types are drum, disc or horizontal belt filters. In each case the filter medium is usually a porous cloth, the permeability of which is chosen to suit the feed particle size. 

Several breakdown processes may occur on storage depending on (i) Particle size distribution and density difference between the droplets and the medium, (ii) Magnitude of the attractive versus repulsive forces which determine flocculation, (iii) Solubility of the disperse droplets and the particle size distribution which determine Ostwald ripening, (iv) Stability of the liquid film between the droplets that determines coalescence. (v) Phase inversion. The various breakdown processes are illustrated in the Fig. 3.32. This is followed by a description of each of the breakdown processes and methods that can be applied to prevent such instability. 

Both the models of Smolik and Zenz predict cyclone separation efficiency as a function of loading purely from knowledge of the efficiency at low loading and the loading itself. Physical and operational factors, such as cyclone geometry and size, solids size distribution and density, inlet velocity and other operating conditions, are not included in these models, and the effect of these parameters is thus not thought to be of primary importance. In the Muschelknautz model, on the other hand, the inlet velocity, the cyclone dimensions, and the mean size and density of the inlet solids all feature. 

The effect of particle-particle frictional interactions on excess pressure loss was investigated in the same way as described above. Smooth tubes were used, with beds of polished glass spheres and sand particles having essentially the same size distribution and density, but differing in their particle-particle frictional properties. Although the slugging... 

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