Both gas and solids

As already indicated, when a liquid is the fluidising agent, substantially uniform conditions pervade in the bed, although with a gas, bubble formation tends to occur except at very low fluidising velocities. In an attempt to improve the reproducibility of conditions within a bed, much of the earlier research work with gas fluidised systems was carried out at gas velocities sufficiently low for bubble formation to be absent. In recent years, however, it has been recognised that bubbles normally tend to form in such systems, that they exert an important influence on the flow pattern of both gas and solids, and that the behaviour of individual bubbles can often be predicted with reasonable accuracy. 

Differential (flow) reactor Integral (plug flow) reactor Mixed flow reactor Batch reactor for both gas and solid... 

Flow systems are developed mainly for liquid samples and their complexity can range from simple to very complex manifolds to deal with ultratrace amounts of the target analyte in complex matrices, which often require on-line separation/preconcentration steps. As a wide variety of chemical manipulations can be carried out in an FI manifold, the scope of the FI applications is enormous. Not only liquid samples, but also both gas and solid samples, can be also introduced into the liquid flow manifold if special adaptations are made. Gas samples simply require impermeable tubing. Solids can be either introduced into the system and leached with the help of auxiliary energy e.g. ultrasound) or introduced as slurries. 

What we mean in this report by equilibrium and disequilibrium requires a brief discussion of definitions. Natural physicochemical systems contain gases, liquids and solids with interfaces forming the boundary between phases and with some solubility of the components from one phase in another depending on the chemical potential of each component. When equilibrium is reached by a heterogeneous system, the rate of transfer of any component between phases is equal in both directions across every interface. This definition demands that all solution reactions in the liquid phase be simultaneously in equilibrium with both gas and solid phases which make contact with that liquid. Homogeneous solution phase reactions, however, are commonly much faster than gas phase or solid phase reactions and faster than gas-liquid, gas-solid and... 

In this study, we adopted a model with one balanced algebraic equation which incorporated various lumps (gas oil, cycle oil, gasoline, light gases) in both gas and solid phase. Hydrocarbons lumps are distributed and coexist between the two phases at all times during the reaction period (before product evacuation) ... 

Once these facts were established, the second phase of the analysis involved the use of Equation (7) with B=0.5, just before product evacuation. In these equations the contribution of various lumps in both gas and solid phases were accounted for simultaneously. 

Br to react with cyclopropane in the solid phase at 77 K. In contrast to the reaction of the same atoms in the gaseous phase where De Jong and co workers found the major product to be methyl bromide, in the solid phase the major product is isopropyl bromide. Table 11 gives the yield of the various products in both gas and solid phases. The... 

Everett (26) developed the thermodynamic analysis for a binary solution of components 1 (probe) and 2 (stationary phase) in the presence of a gas (3), which is insoluble in the solution. Assigning that the molar volume of the probe, V, does not vary greatly with pressure, the gas phases are only slightly imperfect, the system is in equilibrium, and the solute is infinitely dilute in both gas and solid phases, then the infinite dilution mole fraction activity coefficient of component 1 at temperature T and total pressure P can be written as... 

A schematic diagram of the two-reactor fixed-bed system is shown in Fig. 5. The primary reaction occurs in the reactor on the left while regeneration occurs on the right. Dashed lines indicate gas flow paths when the functions of the two reactors are reversed. Both gas and solid concentrations and temperatures (for non-isothermal reactors) are functions of time and axial position. 

Figure 2.1 depicts schematically how such concepts apply for a reaction A = B occurring in a volume of water in contact with both gas and solid phases. The volume of water and its temperature and pressure must be constant. For equilibrium concepts to apply to reaction A = B, the total fluxes of A (Sdn ) and of B (Ldng) must equal zero. The number of moles of A (n ) and of B (og) must be constant and homogeneously distributed throughout the water. Given that the initial concentration of A is (A)o and assuming that the concentration of B is zero to start, we find (B) = A)o - (A). For equilibrium conditions where = (B)/(A), we obtain (A) = (A)J( 1 + K ). 

The first model for the movement of both gas and solids and the pressure distribution around single rising bubbles was given by Davidson and Harrison... 

MILLER also remarked that it is common practice to measure methyl torsion frequencies in solids, often at low temperatures and then to use these frequencies to calculate barrier heights. These barriers certainly should not be mixed with gas-phase barriers. The presence of nearby molecules must contribute to the potential function for the torsion and thus affect the deduced barrier. This is expecially clear in the case of those molecules for which the torsion is forbidden for the gas, but in which it becomes observable in the solid. The appearance in the solid surely is due to the influence of neighboring molecules. The potential no longer has the symmetry of the isolated molecule, or else the band would not be observed. Some day, perhaps, these "barriers from the solid state may give us useful information about intermolecular interactions. In the meantime, there is a real hazard in putting them in the literature without adequate caveats. In molecules for which torsional frequencies have been measured for both gas and solid, it is common to find that they differ by 10 percent, which implies a difference of 20 percent in the barriers. Discrepancies as large as 100 percent are known (e.g., in benzaldehyde). 

A batch reactor for both gas and solid can also be used. 

The thermal diffusion of plutonium in (U,Pu)02+jc mixed oxides was studied by Sari and Schumacher (349), Aitken and Evans (550), Bober et al. (347), and Demas, Natasch, and Maynard (55/). It has been found that plutonium is less diffusive than oxygen, and that it tended to concentrate toward the higher temperature zone. Both gas- and solid-phase transport have been considered for plutonium. The heat of transport of plutonium by solid phase diffusion has been estimated to be — 35 kcal/mol by Bober et al. (347). The increase of Pu/U ratio toward the hotter zone is thought to be caused by preferential vaporization of plutonium in the hotter zones rather than thermal diffusion through the solid phase (347). 

Liquid explosives have different volatilities, which varied the combustion processes. The important characteristic is the variation of reaction phase in the combustion reactions. Generally, because alkyl nitrates and some of alkene nitrates are highly volatile, their combustion reactions proceed in gas state. In contrast, the combustion reactions of nitroglycerine, azide nitrate ether, and aqueous hydrazine proceed in both gas and solid phases. The reactions of mercury fulminate and urea perchlorate mainly proceed in solid state. 

Parameters of both gas and solid phase (represented by gas in equilibrium with the solid surface) can be plotted in a psychrometric chart as process paths. These phase diagrams (no timescale is available there) show schematically how the... 

Fast fluidized bed" Continuous feed of both gas and solids sufficiently high solids Fischer-Tropsch... 

There are quite different flow behaviors on an equipment scale, such as the intensity of gas-solid overall movement and backmixing, gas-solid dispersion, and the residence time distribution (RTD) of both gas and solid in beds. 

The hydrodynamics of a circulating fluidized bed is further complicated by the existence of significant variations in solids concentration and velocity in the radial direction. A more uniform distribution can be achieved at conditions of lower solids concentrations under higher gas flow conditions. In the dilute transport regime, the solids concentration is very low and both gas and solids have short residence times. 

The axial gas dispersion tends to increase with column diameter, as shown above. If both gas and solids... 

Emitters can be classified in terms of those which emit in the gas phase, the solution phase, or the solid state, and also by mode of excitation, i.e. electroluminescence, thermoluminescence, chemiluminescence, radioluminescence and photoluminescence. We are most concerned with photoluminescent materials, but thermoluminescence and electroluminescence, in both gas and solid phases, are important technologies. 

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