Particle characteristic

As a first step, it is essential to know the characteristics of the particles as well as the liquids in a separation process. Most of these data are not found in handbooks or in the open literature. There is a need that the characteristics of both phases must be determined. What may be disturbing is that these properties might be time dependent, being affected by upstream conditions and the aging of the materials (Chow, 1997). 

The size of the particle is the most important separation variable because it affects the particle filterability and its settling rate. The smaller the particles, the more difficult it is to separate from the liquid. So the first step is to determine the particle size. Some of the 

Another important consideration is solids concentration, since this affects the type of separator to be used. In applications with low solids concentration (e.g., less than 50 ppm), sand filters or cartridge filters may be suitable. If the solids concentration is high, then cake filters are used. Electrical charges on particles affect the agglomeration of particles. Zeta potential measurements may be made but the results are unreliable and have not been used industrially. 

The viscosity of the liquid phase is an important consideration. It is a known fact that the sedimentation velocity and the filtration rate vary inversely as the viscosity of the suspending liquid. Temperature, purity, and the amount of dissolved solids materially affect the viscosity value therefore, it is essential that direct measurement of viscosity be made on the solid-liquid system. 

Further, toxicity, volatility, and corrosiveness must be taken into account for environmental and safety reasons. Last, the particle shape and particle strength can be significant when considering the type of equipment to be specified. 

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Dispersion Resins. Polytetrafluoroethylene dispersions in aqueous medium contain 30—60 wt % polymer particles and some surfactant. The type of surfactant and the particle characteristics depend on the appHcation. These dispersions are appHed to various substrates by spraying, flow coating, dipping, coagulating, or electro depositing. 

Torque Rating The choice of torque rating has been discussed earlier. Torque is a function of such factors as quantity and quality of underflow (therefore, of such parameters as particle characteristics and flocculant dosage that affect underflow character), unit area, and rake speed but, in the final analysis, torque must be specified on the basis of experience modified by these factors. Unless one is experienced in a given apphcation, it is wise to consult a thickener or clarifier manufacturer. 

Type of material / Type / Material particle characteristic Mechanical conveying Pneumatic conveying ... 

Typical new equipment design efficiencies are between 99 and 99.9%. Older existing equipment have a range of actual operating efficiencies of 95 to 99.9%. Several factors determine fabric filter collection efficiency. These include gas filtration velocity, particle characteristics, fabric characteristics, and cleaning mechanism. In general, collection efficiency increases with increasing filtration velocity and particle size. 

Primary particles characteristics Packing characteristics Bulk properties... 

An ideal particle moves relative to the fluid with velocity, v, dependent on just four quantities viz. fluid viscosity and density p and p respectively (i.e. fluid properties), and particle solid density and characteristic size ps and d respectively (i.e. particle characteristics), subject to the forces of buoyancy and friction, as illustrated in Figure 2.1. 

Often, it is not necessary to know the total CSD since some mean particle characteristic and possibly its variance may suffice. In general, such characteristics of the CSD can be obtained from the moment equation, below, by... 

Since ly is fixed by the fluid and particle characteristics, uq needs to be kept low... 

A sample of fine catalyst crystals for use in a reactor was found to have the following particle characteristics... 

The particle characteristics obtained in the product depend strongly on the mechanism of agglomeration and the processing conditions. Agglomerates typically have the form shown schematically in Figure 6.1, although the sizes of both primary particles and agglomerates can vary considerably. 

Finally, it should be emphasized that in all these studies more than one particle characteristic should be determined and this will usually entail more than one method of measurement. These can include various sizing techniques and the value of microscopy should not be ignored. Often, however, end-use tests provide the most meaningful data e.g. sedimentation rates or filtrability. 

The significance of this novel attempt lies in the inclusion of both the additional particle co-ordinate and in a mechanism of particle disruption by primary particle attrition in the population balance. This formulation permits prediction of secondary particle characteristics, e.g. specific surface area expressed as surface area per unit volume or mass of crystal solid (i.e. m /m or m /kg). It can also account for the formation of bimodal particle size distributions, as are observed in many precipitation processes, for which special forms of size-dependent aggregation kernels have been proposed previously. 

Jones, G.L., 1984. Simulating the effects of changing particle characteristics in solids processing. Computers and Chemical Engineering, 8, 329. 

Electrons are very light particles and cannot be described by classical mechanics. They display both wave and particle characteristics, and must be described in terms of a wave function, T. Tlie quantum mechanical equation corresponding to Newtons second law is the time-dependent Schrbdinger equation (h is Plancks constant divided by 27r). 

The bubble size at formation varied with particle characteristics. It was further observed that the bubble size decreased with increasing fluidization intensity (i.e., with increasing liquid velocity). The rate of coalescence likewise decreased with increasing fluidization intensity the net rate of coalescence had a positive value at distances from 1 to 2 ft above the orifice, whereas at larger distances from the orifice the rate approached zero. The bubble rise-velocity increased steadily with bubble size in a manner similar to that observed for viscous fluids, but different to that observed for water. An attempt was made to explain the dependence of the rate of coalescence on fluidization intensity in terms of a relatively high viscosity of the liquid fluidized bed. 

Tewa-Tagne, P., Briangon, S. Fessi, H. (2006). Spray-dried microparticles containing polymeric nanocapsules Formulation aspects, liquid phase interactions and particles characteristics. International Journal of Pharmaceutics, Vol. 325, 1-2, (November 2006), pp. (63-74), ISSN 0378-5173... 

We are used to thinking of electrons as particles. As it turns out, electrons display both particle properties and wave properties. The French physicist Louis de Broglie first suggested that electrons display wave-particle duality like that exhibited by photons. De Broglie reasoned from nature s tendency toward symmetry If things that behave like waves (light) have particle characteristics, then things that behave like particles (electrons) should also have wave characteristics. 

The broad spectrum of derived fractional efficiency curves in Fig. 2 simply reflects the effects of cyclone designs deviating from consistence with the basic premises and from ill defined particle characteristics. 

From the research on electrocodeposition to date, a number of variables appear to be influential in the process, which include hydrodynamics, current density, particle characteristics, bath composition, and the particle-bath interaction. The influence that a particular variable has on the process is typically assessed by the change in the amount of particle incorporation obtained when that variable is adjusted. Although the effect of each of these process variables has been reported in the literature, the results are often contradictory. The effects of the process variables, of which many are interrelated, can also vary for different particle-electrolyte systems and electrodeposition cell configurations used. This review will summarize these effects and the contradictions in the literature on electrocodeposition. 

We then wish to discover how tj depends on reaction and particle characteristics in order to use equation 8.5-5 as a rate law in operational terms. To do this, we first consider the relatively simple particle shape of a rectangular parallelepiped (flat plate) and simple kinetics. 

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