Extractor, continuous


Fit a 1-litre round-bottomed flask with a rubber stopper carrying a large Soxhlet extractor (Fig. II, 44, 4), and attach an efficient double surface condenser to the latter. Place 595 g. (750 nil.) of commercial acetone, preferably dried over anhydrous potassium carbonate, and a few fragments of porous porcelain in the flask. Insert two large paper thimbles in the Soxhlet apparatus, one above the other fill each about three quarters full with barium hydroxide and fill the remainder of the space with glass wool (1). Heat the flask on a water bath or steam bath so that the acetone refluxes back into the extractor rather rapidly. Continue the heating until the acetone no longer refluxes when the flask is almost completely immersed in the boiling water bath (72-120 hours). The refluxing may be interrupted at any time for as long as desired without influencing the preparation. Equip the flask with a fractionating column attached to an efficient double surface condenser set for downward distillation. Immerse the flask in an oil bath and raise the temperature gradually to 125° maintain this temperature as long as acetone distils over. The recovery of acetone is complete when the temperature at the top of the column is about 70°. Distil the residue (2) from a Claisen flask under diminished pressure (3) a little acetone passes over first, followed by the diacetone alcohol at 71-74°/23 mm. (or 62-64°/13 mm.). The yield is 450 g.  [c.352]

A continuous ether extractor (see Figs. II, 44, 1-2) gives more satisfactory results.  [c.461]

A continuous extractor (Fig. II, 44, 2) gives the best results and is recommended.  [c.494]

A continuous ether extractor (Fig. II, 44, 2) is recommended.  [c.901]

Dipyridyl. In a 1-htre three-necked flask, equipped with a reflux condenser and mechanical stirrer, place 21 g. of copper powder and 200 ml. of p-cymene (b.p. 176-177°). Whilst refluxing the mixture gently with stirring, add 104 g. of 2-bromopyridine dropwise over a period of 1 hour add three additional portions of 21 g. each of copper powder (through the otherwise closed third neck) during this period. Continue the heating with stirring for a further 2 5 hours, cool, acidify with dilute hydrochloric acid, and separate the p-cymene by steam distillation. Render the residual solution strongly alkahne with concentrated sodium hydroxide solution and steam distil again until the distillate gives only a pale red colouration with ferrous sulphate solution. Saturate the steam distillate with sodium chloride and extract repeatedly with ether it is best to use a continuous extractor (Fig. II, 44, 2). Dry the ethereal extracts over anhydrous potassium carbonate, remove the ether by distillation through an efficient fractionating column (2 2 -dipyridyl is shghtly volatile in ether vapour), and distil the residue under reduced pressure. Collect the 2 2 -dipyridyl (31 5 g.) at 147°/16 mm. it sohdifies on cooling, m.p. 69-70°.  [c.993]

Many continuous extractions involving solid samples are carried out with a Soxhiet extractor (Figure 7.18). The extracting solvent is placed in the lower reservoir and heated to its boiling point. Solvent in the vapor phase moves upward through the tube on the left side of the apparatus to the condenser where it condenses back to the liquid state. The solvent then passes through the sample, which is held in a porous cellulose filter thimble, collecting in the upper reservoir. When the volume of solvent in the upper reservoir reaches the upper bend of the return tube, the solvent and any extracted components are siphoned back to the lower reservoir. Over time, the concentration of the extracted component in the lower reservoir increases.  [c.214]

The countercurrent arrangement (Fig. 5c) represents the best compromise between the objectives of high extract concentration and a high degree of extraction of the solute, for a given solvent-to-feed ratio. The feed entering stage 1 is brought into contact with a B-rich stream which has already passed through the other stages, while the raffinate leaving the last stage has been in contact with fresh solvent. Because of the economic advantages, continuous countercurrent extraction is normally preferred for commercial-scale operations. For the case of a partially miscible ternary system, the number of ideal stages in a countercurrent cascade can be estimated graphically on a triangular diagram, using the Hunter-Nash method (53). The feed and solvent compositions and the resulting mixture point M are first located on the diagram as in Figure 2a. If in addition one of the exit stream (extract or raffinate) compositions is given, a point representing the composition of the net flow in the countercurrent cascade can be located. This point, called the delta point, provides the basis for constmction of material balance lines and tie-lines representing a sequence of ideal stages for the countercurrent extractor. The Hunter-Nash procedure is well known and useflil (5,28). For dilute systems, it is often more convenient to use the delta point constmction on a diagram with solvent-free coordinates (5,28). In this case a rectangular diagram is plotted in which the horizontal axis is the mass fraction of the solute C on a B-free basis, and the vertical axis is the mass ratio of B to A + C.  [c.65]

Holdup and Flooding. The volume fraction of the dispersed phase, commonly known as the holdup can be adjusted in a batch extractor by means of the relative volumes of each Hquid phase added. In a continuously operated weU-mixed tank, the holdup is also in proportion to the volume flow rates because the phases become intimately dispersed as soon as they enter the tank.  [c.69]

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc.  [c.77]

Extractors often contribute substantially to the capital and operating costs of a plant, which provides the impetus to seek ways to reduce the extraction load in order to increase extractor capacity and reduce specific solvent requirements. When the feed material is of plant origin and the solute is contained in cells that can be mptured by heat or pressure, pre-treatment frequendy involves removing part of the solute by pressing. The variety of extractors used in Hquid—soHd extraction is diverse, ranging from batchwise dump or heap leaching for the extraction of low grade ores to continuous countercurrent extractors to extract materials such as oilseeds and sugar beets where problems of soHds transport have dominated equipment development.  [c.90]

The Rotocel extractor (16) achieves countercurrent extraction through a sequence of discrete Hquid—soHd contacts. The soHds to be extracted are fed continuously as a dry material or as a slurry to sector-shaped cells arranged around a horizontal rotor. Each cell has a perforated base which allows easy drainage of solvent into a basin at the base of the cell from which the solvent is pumped into the next cell in the countercurrent direction. Fresh solvent is supphed to the last cell, which also occupies a larger sector than the other cells to allow for drainage of the extracted soHds prior to discharge. The misceUa is filtered by the bed of soHds in each cell, and misceUa from such rotary-type extractors can be expected to contain less than 5 ppm suspended soHds, sometimes effecting a saving on the cost of subsequent soHd—Hquid separation equipment.  [c.91]

An alternative tower design, the Bonotto extractor (15) (Fig. 4), is a series of slowly rotating horizontal trays equispaced vertically in a tall cylindrical vessel. The soHd is fed continuously close to the outside edge on the top tray and a stationary scraper attached to the vessel causes the soHd to cross the tray. The soHd then falls through an opening onto the tray beneath, where another scraper moves the soHd across the tray in the opposite direction toward a similar opening near the periphery of this tray. This sequence of moving the soHd across each plate in opposite directions on alternate plates is continued until the soHd reaches the bottom of the tower. It is then transported from the tower by a screw conveyor, although alternative types of soHds conveyor could be used. The solvent is fed to the bottom of the vessel and flows upward to give a flow countercurrent to the soHds flow direction. Clearly the upward velocity of the solvent should be lower than the fall velocity of the soHds to prevent entrainment of the soHds, and the density of the solvent may change markedly up the column as the concentration of solute increases.  [c.91]

Immersion-type extractors have been made continuous through the inclusion of screw conveyors to transport the soHds. The Hildebrandt immersion extractor (18) employs a sequence of separate screw conveyors to move soHds through three parts of a U-shaped extraction vessel. The helix surface is perforated so that solvent can pass through the unit in the direction countercurrent to the flow of soHds. The screw conveyors rotate at different speeds so that the soHds are compacted as they travel toward the discharge end of the unit. Alternative designs using fewer screws are also available.  [c.93]

Hydrogen Peroxide Recovery. Hydrogen peroxide formed in the oxidation step is usually recovered by countercurrent extraction of the oxidized working solution, using dernineralized water in Hquid—Hquid sieve tray columns. Working solutions used by the principal producers are less dense than water so these would enter near the base of the column and flow upward as the dispersed phase. Water enters the column at the top and increases in hydrogen peroxide content and density as it flows downward as the continuous phase. AH known principal producers use sieve tray columns having these flow paths for extraction. Dependent on the type and composition of the working solution, concentrations of hydrogen peroxide up to 45 wt % are obtained by extraction. For safety reasons, 45 wt % aqueous hydrogen peroxide extract is a reasonable limit for nonmiscible organic systems (67). The columns and trays are usuaHy constmcted from 304 or 316 stainless steel or low carbon equivalents. Aluminum and high grade aluminum aHoys are also adequate materials. The sieve tray extractor s particular advantages are high throughput, reasonably high tray efficiency, and, because they have no moving parts, they are economically maintained. Rate turndown is about 2 1, limited by the dispersed phase droplet size or tray stabHity. Other extract methods involving use of rotating mechanical devices, packed columns, spray columns, and unfiUed columns have been claimed.  [c.476]

The Kennedy extractor (Fig. 18-78), also requiring little head-room, operates substantially as a percolator that moves the bed of solids through the solvent rather than the conventional opposite. It comprises a nearly horizontal line of chambers through each of which in succession the solids being leached are moved by a slow impeller enclosed in that section. There is an opportunity for drainage between stages when the impeller lifts solids above the liquid level before dumping them into the next chamber. Solvent flows countercurrently from chamber to chamber. Because the solids are subjec ted to mechanical action somewhat more intense than in other types of continuous percolator, the Kennedy extractor is now little used for fragile materials such as flaked oil seeds.  [c.1674]

Screw-Conveyor Extractors One type of continuous leaching equipment, employing the screw-conveyor principle, is strictly speaking neither a percolator nor a dispersed-solids extractor. Although it is often classed with percolators, there can be sufficient agitation of the solids during their conveyance by the screw that the action differs from an orthodox percolation.  [c.1675]

Process and Operating Conditions The major parameters that must be fixed or identified are the solvent to be used, the temperature, the terminal stream compositions and quantities, leaching cycle (batch or continuous), contact method, and specific extractor choice.  [c.1676]

Many continuous extractions involving solid samples are carried out with a Soxhiet extractor (Figure 7.18). The extracting solvent is placed in the lower reservoir and heated to its boiling point. Solvent in the vapor phase moves upward through the tube on the left side of the apparatus to the condenser where it condenses back to the liquid state. The solvent then passes through the sample, which is held in a porous cellulose filter thimble, collecting in the upper reservoir. When the volume of solvent in the upper reservoir reaches the upper bend of the return tube, the solvent and any extracted components are siphoned back to the lower reservoir. Over time, the concentration of the extracted component in the lower reservoir increases.  [c.214]

The extraction with ether is continued until the ether leaving the insoluble solid is entirely colorless. This requires twenty-four to seventy-two hours, according to the state of subdivision of the nutmegs and the rate at which the ether is passed through. The ethereal solution is then freed of a small quantity of entrained insoluble matter by filtering through a folded paper. This filtration may advantageously be completed in the type of extractor described in Org. Syn. 2, 49. The clear solution is now entirely freed from ether by distillation on the water bath. The residue weighs 640-690 g. On cooling it sets to a mass of crystals of trimyristin which is filtered with  [c.100]

A continuous extractor has been described earlier in this series.  [c.120]

If the desired product is fairly water soluble, simple extraction into organic solvents may not be an efficient means of recovery. In that case, continuous extraction of the aqueous solution with an organic solvent may be necessary to effect the recovery. Either of two types of apparatus are normally employed, and the correct design depends on the density of the organic solvent. For solvents less dense than water, the apparatus should be set up as in Fig. A3.11a. The barrel of the extractor is charged with the  [c.175]

Fio. A3.11. Continuous extraction setups (a) for solvents less dense than water (b) for solvents more dense than water (c) Soxhiet extractor.  [c.175]

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.  [c.396]

Place the dry calcium malonate in a 2-Utre round-bottomed flask, which is surrounded by a freezing mixture of ice and salt. Place 400 ml. of alcohol-free ether (3) in the flask and stir the mixture vigorously with a mechanical stirrer. Add 450 ml. of concentrated hydrochloric acid (4) gradually through a dropping funnel with bent stem. Remove the ether layer, and extract the aqueous solution five times with 150 ml of ether. Much more satisfactory extraction of the acid is achieved by the use of a continuous extractor (Figs. II, 44, 1 and II, 44, 2) and this procedure is recommended. Dry the ethereal solution with anhydrous sodium or magnesium sulphate and distil off the ether on a water bath. The residue (malonic acid) crystallises and, after drying in the air, melts between 132° and 134° according to the purity of the chloroacetic acid originally employed. The yield is 215 g. This acid is sufficiently pure for most purposes, but if it is required perfectly pure it may be crystallised from benzene - ether containing 5 per cent, of light petroleum (b.p. 60-80°] the m.p. of the pure acid is 136°.  [c.491]

The value of d is a mean value, based on a broad distribution of si2es. In a mass-transfer situation the smallest drops, because of the very high specific surface area, quickly come to equiUbrium conversely the largest drops, which typically have a diameter of about 2 d, are much slower to come to equihbrium with the continuous phase. The effects of drop si2e distribution on extractor performance are being studied (68—70), although the single parameter d is stiU widely in use for design work.  [c.69]

The BoUman extractor (15) (Fig. 3) is a moving-bed, perforated-basket type of extractor. The soHds are loaded into baskets fixed to a chain conveyor in a closed vessel. SoHd is fed to the top basket on the downward side of the conveyor and is discharged from the top basket on the upward side. Fresh solvent is sprayed on the soHd about to be discharged, leaving some time for drainage from the basket before discharge is effected, and passes downward through the baskets to effect a countercurrent flow. The partially rich solvent (half-misceUa) from the bottom of the upward side is pumped to the basket at the top of the downward side, from which solvent flows from basket to basket in cocurrent fashion. The final solvent solution, misceUa, is coUected from the bottom of the downward side. Control of flake size during pre-treatment is desirable, as is control of the thickness and bulk density of the bed. A typical extractor moves at about 0.3 m/s, each basket contains some 350 kg of seeds, about equal masses of seeds and solvent are used, and the misceUa contains about 25% oil by mass (2). Advantages of this design of extractor are that a soHds-free misceUa can be obtained, the residue is weU drained when the equipment is properly controUed, and large quantities of soHds can be extracted continuously.  [c.90]

Use of Desiccants and Chemical Means to Remove Water. Another means to remove the water of esterification is calcium carbide supported in a thimble of a continuous extractor through which the condensed vapor from the esterification mixture is percolated (41) (see Carbides). A column of activated bauxite (Elorite) mounted over the reaction vessel has been used to remove the water of reaction from the vapor by adsorption (42).  [c.376]

Coalescence The coalescence of droplets can occur whenever two or more droplets collide and remain in contact long enough for the continuous-phase film to become so thin that a hole develops and allows the liquid to become one body. A clean system with a high interfacial tension will generally coalesce quite rapidly. Particulates and polymeric films tend to accumulate at droplet surfaces and reduce the rate of coalescence. This can lead to the ouildup of a rag layer at the liquid-hquid interface in an extractor. Rapid drop breakup and rapid coalescence can significantly enhance the rate of mass transfer between phases.  [c.1470]

Packed Towers For a packed-tower liquid-liquid extractor the empty shell of a spray tower is filled with packing to reduce the vertical circulation or the continuous phase. The standard commercial packings used in vapor-hquid systems are also used in liquid-hquid systems. This includes Raschig and paU rings, Berl and Intalox saddles, and other random-dumped packings as well as the newer structured packings. The packing reduces the available free space for flow but also significantly reduces the height required for mass transfer. However, Nemunaitis, Eckert, Foote, and Rollinson [Chem. Eng. Prog., 67(11), 60 (1971)] reported little benefit from a packed height greater than 3.05 m (10 ft) and recommended redistributing the dispersed phase about every 1.52 to 3.05 m (5 to 10 ft) to generate new droplets and mass-transfer surfaces. From this perspective the packing allows a wider spacing between sieve plates than described for a conventional sieve-plate tower.  [c.1476]

Methoos of Operation Leaching systems are distinguished by operating cycle (batch, continuous, or nmltibatch intermittent) by direction of streams (cocurrent, countercurrent, or hybrid flow) by staging (single-stage, multistage, or differential-stage) and by method of contacting (sprayed percolation, immersed percolation, or solids dispersion). In general, descriptors from all four categories must be assigned to stipulate a leaching system completely (e.g., the Bollman-type extractor is a continuous hybrid-flow multistage sprayed percolator).  [c.1673]

The solution must be extracted exhaustively, the checkers found that thirty such extractions were required to remove all the product. A continuous extractor might be used at this point and certainly would be ncccssar for large-scale runs.  [c.89]

B. Tropohne. In a 1-1., three-necked, round-bottomed flask equipped with a mechanical stirrer, addition funnel, and reflux condenser are placed 500 ml. of glacial acetic acid and then, cautiously, 100 g. of sodium hydroxide pellets. After the pellets have dissolved, 100 g. of 7,7-dichlorobicyclo[3.2.0]hept-2-en-6-one is added and the solution is maintained at reflux under nitrogen for 8 hours. Concentrated hydrochloric acid is then added until the mixture is about pH 1 approximately 125 ml. of acid is required. After the addition of 1 1. of benzene, the mixture is filtered and the solid sodium chloride is washed with three 100-ml. portions of benzene. The two phases of the filtrate are separated and the aqueous phase is transferred to a 1-1. continuous extractor (Note 8) which is stirred magnetically. The combined benzene phase is transferred to a 2-1. pot connected to the extractor and the aqueous phase is extracted for 13 hours. Following distillation of the benzene, the remaining orange liquid is distilled under reduced pressure  [c.118]

It is worth noting that the extractive process can be performed continuously. Thus, the separation of ( )-mandelic acid into its enantiomers was achieved with a liquid particle extractor described by Abe et al. [190-192] using A-docecyl-L-proline as chiral selector.  [c.16]


See pages that mention the term Extractor, continuous : [c.880]    [c.1472]    [c.1480]    [c.396]   
Organic syntheses Acid anhydrides (1946) -- [ c.23 , c.49 ]

Organic syntheses Biclormethyl ether (1956) -- [ c.4 , c.30 ]