Entrainers, description

Anhydrous Acetic Acid. In the manufacture of acetic acid by direct oxidation of a petroleum-based feedstock, solvent extraction has been used to separate acetic acid [64-19-7] from the aqueous reaction Hquor containing significant quantities of formic and propionic acids. Isoamyl acetate [123-92-2] is used as solvent to extract nearly all the acetic acid, and some water, from the aqueous feed (236). The extract is then dehydrated by azeotropic distillation using isoamyl acetate as water entrainer (see DISTILLATION, AZEOTROPIC AND EXTRACTIVE). It is claimed that the extraction step in this process affords substantial savings in plant capital investment and operating cost (see Acetic acid and derivatives). A detailed description of various extraction processes is available (237). 

The theory for plane jets is similar to descriptions of circular jets (see Section 7.4) and many derived equations describe both two-dimensional (plane) and three-dimensional (round) jets. The principle is to generate such high air velocity that a shield against pressure difference, temperature difference, and wind velocity is sustained. Howeveg it is not possible to have complete separation by an air curtain. The main reason for this, is that the jet entrains air... 

The Texaeo Gasifieation proeess is a eontinuous, entrained flow, pressurised, non-eatalytie partial oxidation process in whieh earbonaeeous solids, liquids or gases reaet with oxygen. Gasification breaks the polymer ehains and eonverts the hydroearbons to their simplest forms. A detailed description is given of the proeess and its eommereial applieation. The proeess is a eommereially... 

Ghadiri et al. (1992b, 1994, 1995) developed a more fundamental approach. They consider the particles entrained into the jet and relate the production of attrited fines to the attrition rates obtained from single particle impact tests (cf. Sec. 4.3). According to their model, it should be possible to predict jet attrition rates in fluidized beds on the basis of single particle impact tests combined with a detailed description of the jet hydrodynamics. 

More recently Hewitt (H5) has adapted a downward-film-flow analysis by Dukler (D4) based upon the Deissler velocity profile, to upward film flow this approach, also requiring numerical solution, is claimed to give better correlation of film thickness with theory, over wider ranges than previous data, and for different types of liquid injections. The Deissler velocity profile was developed specifically to describe the velocity variation in the zone close to a solid wall, and, might be expected to give the best description of film flow. However, when gross wave motion or significant entrainment occurs, this correlation also shows deviations from experiment. 

We have modified the SNCR reaction mechanism from the previous problem to include the simple mixing description (SNCRmix.mec). Here the entrainment of the reactive components of the flue gas (NO and O2) into the NH3/carrier jet (inverse mixing) is described by the two pseudo reactions,... 

As organic and aqueous phases are macroscopically separated by the membrane, HFM offer several hydrodynamic advantages over other contactors, such as the absence of flooding and entrainment, or the reduction of feed consumption (160, 161). The flowsheets tested in HFM were similar to those developed for centrifugal contactor tests. Computer codes based on equilibrium (162) and kinetics data, diffusion coefficients (in both phases and in the membrane pores), and a hydrodynamic description of the module, were established to calculate transient and steady-state effluent concentrations. It was demonstrated that, by selecting appropriate flow rates (as mass transfer is mainly controlled by diffusion), very high DFs (DI A 11 = 20,000 and DFrm = 830) could be achieved. Am(III) and Cm(III) back-extraction efficiency was up to 99.87%. 

Zender C.S., Bian H., and Newman D. (2003). Mineral dust entrainment and deposition (DEAD) model Description and 1990s dust climatology. /. Geophys. Res., 108(D14), AAC8/1-AAC8/19. 

Description Hydrocarbon feed is pumped to the liquid-liquid extraction column (1) where the aromatics are dissolved selectively in the sulfolane water-based solvent and separated from the insoluble non-aromatics (paraffins, olefins and naphthenes). The non-aromatic raffinate phase exits at the top of the column and is sent to the wash tower (2). The wash tower recovers dissolved and entrained sulfolane by water extraction and the raffinate is sent to storage. Water containing sulfolane is sent to the water stripper. 

Description Hydrocarbon feed is preheated with hot circulating solvent and fed at a midpoint into the extractive distillation column (EDC). Lean solvent is fed at an upper point to selectively extract the aromatics into the column bottoms in a vapor/liquid distillation operation. Nonaromatic hydrocarbons exit the column top and pass through a condenser. A portion of the overhead stream is returned to the column top as reflux to wash out any entrained solvent. The balance of the overhead stream is the raffinate product, requiring no further treatment. 

A detailed description of the experimental apparatus and procedure used for the aqueous study are given elsewhere (Roop and Akgerman, Ind. Eng. Chem. R., in review) Static equilibrium extractions were carried out in a high pressure equilibrium cell (300 mL Autoclave). After the vessel is initially charged with 150 mL of water containing 6.8 wt.% phenol and supercritical carbon dioxide (and a small amount of entrainer, if desired), the contents were mixed for one hour followed by a two hour period for phase separation. Samples from both the aqueous phase and the supercritical phase were taken for analysis and the distribution coefficient for phenol calculated. 

Part 23 of ISO 787 contains a description of an alternative method which allows to remove air entrained in the sample of a powdered material. The powder is placed in a special tube, mixed with an excess of the displacement liquid more than sufficient to cover its surface, and placed in centrifuge to remove air. 

Consider a molecule diffusing in free space or a solute molecule diffusing in solution. Upon colliding with a surface, assume that the molecule is sufficiently entrained by surface forces that there results a reduction in dimensionality of its diffusion space from d = 3 to d — 2, and that in its subsequent motion the molecule is sterically constrained to follow the pathways defined by the lattice structure of the surface (or, perhaps, the boundary lines separating adjacent domains). If at some point in its trajectory the molecule becomes permanently immobilized, either because of physical binding at a site or because an irreversible reaction has occurred at that site, then, qualitatively, this sequence of events is descriptive of many diffusion-reaction processes in biology, chemistry and physics. 

From the description of conditions that are required to obtain a fluidized bed it is obvious that the size distribution of the particles in the fluidized bed must be narrow. Larger particles will not be sufficiently lifted by the gas and sink down. This effect can be and often is used to accomplish discharge of agglomerates that have grown to the proper size. At the other extreme, if the particles are too small, they are entrained in the gas and carried out of the chamber. Such solids must be removed from the off-gas in dust collectors and are normally recirculated, either to the liquid feed stock for redispersion and drying or directly into the fluidized bed for reagglomeration. 

Eight types of cement are covered in ASTM C 150 and AASHTO M 85. These types and brief descriptions of their uses are listed in Table 31.1. Although lA, IIA, and IIIA (air-entraining cements) are available as options, concrete manufacturers prefer to use an air-entraining admixture during concrete manufacture, where they can get better control in obtaining the desired air content. 

Both venturi scrubbers and disintegrators are used with cupola systems. Descriptions of these systems are given in Section 4.5.1.3. A separator to remove small particles entrained in water droplets, is located after the wet scrubber. 

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