Design extractor

The primary task in the design of an extractor for a liquid-liquid extraction process is the determination of the number of stages needed to achieve the separation required. 

Fresh solvent fed to each stage, the raffinate passing from stage to stage. 

The extracting solvent fed co-currently with the raffinate, from stage to stage. 

Counter-current flow is the most efficient method and the most commonly used. It will give the greatest concentration of the solute in the extract, and the least use of solvent. 

A fuller discussion of the various classes of diagram used to represent liquid-liquid equilibria is given in Volume 2, Chapter 13 see also Treybal (1980) and Humphrey et al. (1984). 

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Initial Extraction Technique Continuous extraction apparatus was employed, including an extractor designed to contain the starting plant materials, a distillation flask to hold the solvent mixture, the flask being equipped with a reflux condenser, a drip device to facilitate the removal of the volatilized mixture from the condenser and to percolate it through the continuous extractor, and a Soxhiet type return. Means for heating the continuous extraction system were provided. 

Flow and mass transfer the transport of the two phases through an extractor and the production of intensive phase contact are complex hydrodynamic problems. Mass transfer provides the main dimensions of the extractor. This chapter is chiefly interested in a suitable extractor design, but also in the restrictions of the calculation. 

The Model 50 Supercritical Fluid Microextractor from the Suprex Co. (Pittsburgh, PA) was adapted for this design. A schematic of our multi-vessel extractor design can be found in Figures 1 and 2, for six and twelve multi-vessel systems, respectively. The following is a detailed description of the main components. The design, explained here for the extraction from six and twelve vessels is in principle applicable to any number of vessels, provided that other components of the system are scaled up. 

Extractor designs that minimize squeeze pressure and juice contact time with the albedo will produce grapefruit juices with... 

Our industry is starved for data such as that shown in Fig. 7.10 and Table 7.4. Perhaps books and technical journal articles will eventually supply much missing information on these liquid-liquid extraction process areas. Nonetheless, these data as presented herein have been used successfully in many extractor design and rating solutions, and will no doubt be used in the same applications in the future. These tried and proven data are the best choice if actual field operating data with laboratory backup are not available. 

Pilot-scale testing remains an inevitable preliminary to a full-scale extractor design for any new commercial process. The pilot-scale extractor should be of the same type as the full-scale extractor. In the present stage of knowledge, reliable scale-up to industrial-scale extractors still depends on the correlations based on extensive performance data collected from pilot-scale and large-scale extractors covering a wide range of liquid systems. 

A small-scale chain conveyor type of extractor was developed in the 1940s at Iowa State University with the intent of using trichloroethylene solvent to extract soybeans. Crown Iron Works of Minneapolis, Minnesota, licensed the technology and extractor design, and supplied several continuous solvent extraction plants in 1951 using the new extractor and trichloroethylene solvent (6). The meal from these plants proved detrimental to animals, so the plants were either closed or converted to petroleum-based solvents (7). The chain-type extractor apparatus continued on and is the basis of the modern Crown Iron Works Model III extractor used today. 

In comparing two different extractor designs, the contact time can be similar, despite very different configurations ... 

Cartridge case such as Cl is extracted vrocn the breech 22 of barrel 13 by an extractor designated for example in FIG. 7 by the numeral 48. As the cartridge case such as Cl moves toward the left in unison with the bolt 21, ejector pin 49 strikes the cartridge case Cl and drives the case downwardly and outwardly through the ejector opening 50 formed in frame I. This action is depicted in FIG. 8. Of course the ejec-... 

With regard to equipment design, it is critically important to work closely with equipment vendors or others experienced in scale-up. Published models should be considered as tools for an initial engineering design only, and a not as a replacement for pilot testing and consulting with those experienced in extractor design. 

Fig. 5.11. Novel focused microwave-assisted extractor design. (Reproduced with permission of SEV, Mexico.)...

The RDC has a moderate throughput typically in the range of 20 to 35 mV(h m ) [500 to 850 gal/(h ft )j, and it can be turned down to 20 to 35 percent of the design rate. However, the relatively open arrangement leads to some bacWixing and results in only moderate mass-transfer performance. As a consequence, some RDC columns are being replaced by more efficient extractor designs. The RDC can be... 

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