Particles processes

P. Somasundaran, ed.. Fine Particles Processing Vols. 1 and 2, AIMME, New York, 1980. 

An estimation of the multiphase viscosity is a preliminary necessity for convenient particle processing. For particle-doped liquids the classical Einstein equation [20] relates the relative viscosity to the concentration of the solid phase ... 

The propagator K can be interpreted as the Green s function for computing amplitudes for one-particle processes relative to the amplitude that the vacuum remain a vacuum under the influence of the external potential. To lowest order the amplitude that the vacuum remain a vacuum is given by... 

Observables, rate of change of, 477 Occupation number operator, 54 for particles of momentum k, 505 One-antiparticle state, 540 One-dimensional antiferromagnetic Kronig-Penney problem, 747 One-negaton states, 659 One-particle processes Green s function for computing amplitudes under vacuum conditions, 619... 

The catalytic hydrogenation of fatty oils, the desulfurization of liquid petroleum fractions by catalytic hydrogenation, Fischer-Tropsch-type synthesis in slurry reactors, and the manufacture of calcium bisulfite acid are familiar examples of this type of process, for which the term gas-liquid-particle process will be used in the following. 

The area of interest covered by this paper is limited to processes in which chemical conversion occurs, as in the processes noted above. Gas-liquid-particle processes in which a gaseous phase is created by the chemical reaction between a liquid and a solid (for example, the production of acetylene by the reaction between water and carbide) are excluded from the review. Also excluded are physical separation processes, such as flotation by gas-liquid-particle operation. Gas absorption in packed beds, another gas-liquid-particle operation, is not treated explicitly, although certain results for this operation must necessarily be referred to. 

The gas-liquid-particle processes considered in this paper may be grouped into two major classes. In the first, components of all three phases participate in the chemical reaction. In the second, components of only the gaseous and the solid phases participate in the chemical reaction, the liquid phase functioning as a chemically inactive medium for the transfer of momentum, heat, and mass. Important examples of these two types of processes are described, respectively, in Sections II,A and II,B. 

A gas-liquid-particle process termed cold hydrogenation has been developed for this purpose. The hydrogenation is carried out in fixed-bed operation, the liquefied hydrocarbon feed trickling downwards in a hydrogen atmosphere over the solid catalyst, which may be a noble metal catalyst on an inert carrier. Typical process conditions are a temperature of 10°-20°C and a pressure of 2.5-7 atm gauge. The hourly throughput is as high as 20-kg hydrocarbon feed per liter of catalyst volume. 

Sorbitol is produced by a gas-liquid-particle process in which a solution of glucose is hydrogenated in the presence of a solid catalyst consisting of nickel on diatomaceous earth carrier (B6). 

A number of important gas-liquid-particle processes fall outside the categories of Sections II,A and II,B. The review of gas-liquid-particle operations in the following sections is written with particular regard to applications in processes of the types already referred to, but may also be of some significance with regard to other types. A few examples of such processes will be briefly mentioned below. 

Gas absorption in packed beds may be described as a gas-liquid-particle process involving reacting gas and liquid phases and an inert particle phase, the latter functioning mainly as a momentum-transfer medium. 

Processes in which two phases react and result in the formation of a third form an important group of gas-liquid-particle processes. In the production of acetylene, a gaseous phase is formed by reaction between a liquid and a particle phase water and carbide. In the production of gas hydrates in desalination processes, a particle phase is formed by reaction between a liquid and a gaseous phase sea water and, for example, propane. In the melting of gas-hydrate or ice crystals a liquid phase is formed when gaseous and particle phases are brought in contact. 

Trickle-flow operation is widely used for large-scale gas-liquid-particle processes, as noted in Section II. 

In this section, a number of important elementary process steps into which a gas-liquid-particle process can be subdivided will be mentioned. Several theoretical models proposed in the literature will be discussed, and a slightly more comprehensive model will be described. 

The most complex type of gas-liquid-particle process is one in which gaseous components participate in a heterogeneous catalytic reaction, with the formation of gaseous products. The following elementary steps must occur in a process of this type ... 

The process steps mentioned are not of importance in all gas-liquid-particle processes. In particular, the last step does not occur in processes in which a liquid product is formed by reaction between gaseous and liquid reactants, as may be the case, for example, in the catalytic hydrogenation of liquid petroleum fractions. 

A more general model of gas-liquid-particle processes than those that have so far appeared in the literature would, it seems, be of considerable interest as a basis for comparing the reaction-engineering properties of the several types of gas-liquid-particle operations, and as a means for analyzing operations with finite liquid flow (for example, trickle-flow operation and gas-liquid fluidization). 

Trickle-flow operation is probably the most widely used operation for large-scale industrial gas-liquid-particle processes. It has been the subject of a large number of investigations, and is, as a result, relatively well described. 

Further work regarding the axial dispersion of gas in irrigated packed beds seems needed, and it may be noted, with particular regard to gas-liquid-particle processes, that no results have been reported for beds of cylindrically or spherically shaped packing materials. 

Miller RJ, Smith CR, DeMaster DJ, Pomes WL (2000) Feeding selectivity and rapid particle processing by deep-sea megafaunal deposit feeders A " Th tracer approach. J Mar Res 58 653-573 Moore RM, Hunter KA (1985) Thorium adsorption in the ocean - reversibility and distribution amongst particle sizes. Geochim Cosmochim Acta 49 2253-2257 Moore RM, Millward GE (1988) The kinetics of reversible Th reactions with marine particles. Geochim Cosmochim Acta 52 113-118... 

Energetic Materials - Particles Processing and Characterization, Ed. Teipel, U.,WILEY-VCH Verlag, Weinheim, Germany, 2005, ISBN 3-527-30240-9... 

Baldauf, H. and Schubert, H., 1980. Fine Particles Processing, 1(39) 767 - 786 Ball, B. and Richard, R. S., 1976. The chemistry of pyrite flotation and depression. In Flotation, A. M. Gaudin Memorial volume, M. C. Fuerstanau(eds.), AIME, Inc., 1 458 - 484 Basiollio, C., Pritzker, M. D., Yoon, R. H., 1985. Thermodynamics, electrochemistry and flotation of the chalcocite-potassium ethyl xanthate system. SME-AIME Annual Meeting, New York, Preprint No. 85 - 86... 

Klohn-Crippen Consultants, Ltd., has developed the ex situ ChemTech soil treatment process for the removal of heavy metals and organic contaminants from contaminated soil and sediment. The ChemTech process uses two mechanisms to remove contaminants physical scouring of the soil particle surface and chemical leaching of the contaminants from the soil particles. Processing takes place using a three-phase fluidized bed. The technology has been evaluated in pilot-scale... 

Geldart D. Estimation of basic particle properties for use in fluid-particle process calculations. Powder Technol 1990 60 1-13. 

Teipel, U. (ed.) (2005) Energetic Materials Particle Processing and Characterization, Wiley-VCH Verlag GmbH, Weinheim, Germany, Chs 2, 3, 5 and 7. 

---