Extraction equipment centrifuges

Extraction equipment, 476-490 centrifugal, 484,487,490 comparison of types, 477 mixer-settlers, 477, 479 packed towers, 478,480,482,485 87 performance comparison, 478 pulsed towers, 481,483,487 REX2 (rotating disk contactor), 482, 487... 

Timothy C. Frank, Ph.D. Research Scientist and Sr. Technical Leader, The Dow Chemical Company Member, American Institute of Chemical Engineers (Section Editor, Introduction and Overview, Thermodynamic Basis for Liquid-Liquid Extraction, Solvent Screening Methods, Liquid-Liquid Diversion Fundamentals, Process Fundamentals and Basic Calculation Methods, Dual-Solvent Fractional Extraction, Extractor Selection, Packed Columns, Agitated Extraction Columns, Mixer-Settler Equipment, Centrifugal Extractors, Process Control Considerations, Liquid-Liquid Phase Separation Equipment, Emerging Developments)... 

The simplest type of extraction equipment is the stirred tank, coupled with a solid-liquid separation step such as a screen, filter, or centrifuge to separate the marc from the extract. This equipment is readily available in a wide variety of sizes and can be operated as a single-batch extractor or run in series in a countercurrent mode as shown in Figure 11.6. 

If a screen is installed at the bottom of the tank, the solid-liquid separation can take place within the extraction equipment. The extract drains out of the tank, leaving the solids behind. Water can then be added to reslurry the solids, washing solvent from the marc. However, some means of removing the washed marc from a tank equipped with a screen is needed. Where external filtration or centrifuging equipment is used, solvent can be removed from the marc by water washing or conveying to an external dryer. 

Extraction equipment can be classified by function as providing discrete stages or continuous differential contact. Separation may be by gravity alone or by centrifugal force. Additional energy may be applied to control drop size, either by mechanical agitation or pulsation. This classification is shown in Table 1, along with major examples of available equipment. 

Proprietary Extractors. Manufacturers or proprietary design extraction equipment (such as the Podbielniak Centrifugal Extractor or the RTL (raining bucket) Contactor) provide catalogs listing the relative capacities of the various sizes of equipment which are offered. Pilot equipment is usually available for determining extraction performance, and the manufacturer utilizes both the pilot data and experience with similar systems to provide assured commercial designs. 

FIG. A.l. Different types of continuous extraction equipment, (a) Mixer-settler, (b) Spray column, (c) Pulsed column, (d) Tubular centrifugal contactor. 

Apart from the extraction equipment itself, columns, mixer-settlers, or centrifugal extractors, the remainder of the plant is usually fairly conventional. It is usually necessary to provide vessels for conditioning the feed solution to the correct acidity or for correcting the concentrations of the principal solute or other salts. This may be carried out continuously or in special batch conditioning vessels. In the latter case, batch feed vessels will also no doubt be required. 

Acetone powder (1.5 g) was extracted 4 times with 0.1 M sodium borate buffer (pH 7.6) at 4°C, homogenizing each time with a glass grinder equipped with a Teflon pestle. The first extraction was carried out with 80 ml of the buffer, followed by 3 times with 70 ml each of the buffer. Each homogenate was centrifuged at 16,000 g for 5 min. All supernatants were combined. 

In conclusion, the technology of total liquefaction of apple allows to work with a continuous process with less labour and faster than with a classical one, to get a high and constant yield during the whole processing season at a very high level (93- 95%), to get a pulp with a low content of solids (about 20% in volume) which can be centrifuged instead of pressed (lower investment in equipment), to decrease the quantity of waste pomace, to decrease the production costs. Liquefaction technology allows to process different fruits with the same process, at last to liquefy fruits for which no equipment had been developed to extract the juice or for which the use of pectinases did not allow to get juice such as tropical fruits. 

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