Of inert particles

Copeland A process for oxidizing organic wastes in a fluidized bed of inert particles. The wastes may be solid, liquid, or gaseous, and the oxidant is air. Inorganic residues are collected as granular solids and the heat generated is normally utilized. Developed and marketed by Copeland Systems, Oak Brook, IL, United States, and used in a wide variety of industries. 

The direct sterilisation of particulafe solid foods in a gas-solid fluidized bed was proposed as long ago as 1968 by Lawrence et al. (1968) who sterilised wheat flour in steam-air mixtures at the pilot scale. However, Jowitt (1977) described an atmospheric pressure process for fhe sferilisation of canned foods in which the cans are immersed in a fluidized bed of inert particles. This has a number of advantages compared to the conventional retorting process using pressurised steam or hot water ... 

This means that an aqueous salt solution should not be viewed as a homogeneous liquid with a modified inter-molecular interaction, but rather as a colloidal suspension of inert particles in pure liquid water, with the particles formed by the ions and their first solvation shells. Following this view of an aqueous salt solution, the viscosity at low concentration can be described by the Einstein equation [19] ... 

The operation of a gel filtration column is illustrated in Figure 3.9. The stationary phase consists of inert particles that contain small pores of a controlled size. Microscopic examination of a particle reveals an interior resembling a sponge. A solution containing solutes of various molecular sizes is allowed to pass through the column under the influence of continuous solvent flow. Solute molecules larger than the pores cannot enter the interior... 

Preferential negative adsorption of hydrogen ions compared with hydroxyl ions is reflected in the electrophoretic mobility-pH curve for hydrocarbon oil droplets (see Figure 7.7). The magnitude of the electrophoretic mobilities of inert particles such as hydrocarbon oil droplets (c 0 to -6 x 10-8 m2 s V-1) is comparable with those of simple ions (e.g. —7.8 x 10"8 m2 s 1 V-1 for Cl ions at infinite dilution in aqueous solution at 25°C), which, in view of their relatively large size, reflects a high charge number. 

C. Buelens, A Model for the Codeposition of Inert Particles with a Metal, Phd-thesis, Catholic University of Leuven (1984). 

Consider the steady operation of a fixed-bed catalytic reactor in which only heterogeneous reactions occur. The practical measure of reaction space is now the catalyst mass rather than the reactor volume, which can vary according to (i) the density to which the catalyst bed is packed and (ii) the volume fraction of inert particles used by the experimenter to dilute the catalyst, thus reducing temperature excursions in the reactor. Let mc z) be the catalyst mass in an interval (0, z) of the reactor, and let R,Zimc be the molar production rate of species i in a catalyst mass increment Arric. Then Eq. (3.1-4) for that increment takes the form... 

Liquid-fluidized beds predate gas-fluidized beds, but they have considerably fewer applications because of a smaller number of advantages. Most applications are physical, with bioreactors being the sole significant reactor application. Much of the recent attention has focused on aerobic wastewater treatment and fermentation processes, e.g., with methane as the organic substrate (see Refs. " for more details). In these processes, microbial cells are attached to the surface of inert particles (e.g., sand or activated carbon) as a biofilm, or trapped within the pores or interior of particles, causing the particle size and/or density to vary with time. Loaded particles therefore have... 

In essence, diluting the catalyst bed with appropriate size of inert particles increases liquid holdup, improves catalyst wetting, and reduces liquid backmix-ing. The selection of diluent size depends on several factors such as the length and inner diameter of the reactor, the size, shape and amount of catalyst, and the fiow rate of reactants. Therefore, there is a lot of research interest to determine the appropriate size of the diluent for various sizes of small-scale reactors to overcome their limitations. 

Some waste feeds may contain a combination of abrasive particles and sticky salts. This can sometimes provide a benefit as tbe abrasive particles can scour the process surfaces and keep them sufficiently clear of solids buildup. U.S. Patent No. 5,620,606 teaches the addition of inert particles to SCWO feed to mitigate sohds build-up. 

In fluidised bed combustion particles of coal generally in the size range that may be up to 25 mm, are burnt within a bed of inert particles suspended in an air stream. The gas flow is adjusted so that all but the finer particles are retained in the bed which behaves as a fluid. Good mixing and even temperature distribution are the hallmarks of fluid bed combustors. Fig. 16.16 illustrates the principle of fluidised bed combustion. 

An alternative technology to mass bum that overcomes some of the problems of waste combustion is the use of a fluidised bed. In this method of waste reduction the waste (solid or liquid) is fed directly into a bed of inert particles (e.g. sand)... 

An increase of the limiting current density can be achieved by using a fluidized bed of inert particles (e.g. glass beads) with diameters of several tenths of a millimeter up to about... 

The advantages of a fluidized bed of inert particles can best be judged from the dependence of the limiting current, j, on... 

The electrolyser must be provided with a grid or mesh forming the bottom of the bed of inert particles, and with another such a grid at the outlet, preventing the particles from escaping into the reservoir. The whole equipment is shown schematically in Fig. 9. To maintain constant pH of the solution, a glass electrode and a device for controlled addition of an acid or a base can be placed in the reservoir. 

Figure 9. Scheme of an electrolyser with a fluidized bed of inert particles. 1 Electrolyte, 2 inlet grid, 3 outlet grid, 4 flow meter, 5 valve, 6 pump, 7 reservoir. 

To achieve the above-mentioned objective, the following processes have to be considered (a) formation of H+ at an oxidized anode area (decrease of pH) and OH at a reduced cathode area (increase of pH) (b) dissociation of soluble compounds within an entire length of cell (c) movement of cations and anions into respective electrodes (d) displacement of negatively charged and pH-dependent colloidal particles of clays toward the anode (e) formation of pH-dependent complexes of EDTA-metals and their transport toward the anode (f) electroos-motic transport of inert particles (phenanthrene compound) toward the cathode (g) amphoteric surfactant behavior (in the presence of a variable pH within the cell), formation of micelles, and desorption of phenanthrene (h) displacement of micelles and their transformation and (i) transport and removal of conditioning liquids. 

Anderson et al. examined the effect of altering inspiratory flow rate on the regional lung deposition of inert particles and on the pulmonary response to histamine aerosol. In one experiment, six healthy nonsmokers inhaled 6-pm Teflon particles that were labeled with the radioisotope indium 111 (" In) at 0.04 and 0.5 L/s. Tracheobronchial deposition averaged 50% after inhaling at 0.04 L/s, compared to 30% after inhaling at 0.5 L/s. Alveolar deposition increased from 1 to 28% with the lower inspiratory rate (69). 

Liquid suspension Drum Fluid/spouted beds of inert particles... 

Group D (vibrated FBDs, baffled FBDs, spouted FBDs) Spray onto a bed of inert particles (inert solids FBDs) Spray onto absorbent particles (silica gel, biomass) Spouted FBDs... 

Costa, E.F., Cardoso, M., and Passos, M.L., Simulation of drying suspensions in spout-fluid beds of inert particles. Drying Technol, 19(8), 1975-2001, 2001. 

Taruna, I. and Jindal, V.K., Drying of soy pulp (okara) in abed of inert particles. Drying Technol, 20(4-5), 1035-1051,2002. 

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