US2011186A - Process and apparatus for intimately contacting fluids - Google Patents

Description

Aug. 1935- w. J. D. VAN bucK 2,011,186

PROCESS AND APPARATUS FOR INTIMATELY C O NTACTING FLUIDS Filed Feb. 16, 1934 2 Sheets-Sheet l Aug. 13, 1935.

W. J. D. VAN DIJCK PROCESS AND APPARATUS FOR INTIMATELY CONTACTING FLUIDS Filed Feb. 16, 1934 2 Sheets-Sheet 2 FIG. 4

lnvenbw \NJD. \lan Dijc iimz Patented Aug. 13, 1935 PATENT OFFlC PROCESS AND APPARATUS FOR INTI- MATELY CONTACTING FLUIDS I Willem JohannesDominicus van Dijck, The Hague, Netherlands Application February 16, 1934, Serial No. 711,487 In the Netherlands February 11, 1933 5 Claims. (Cl. 23-270) This invention relates to a process and apparatus for bringing into intimate contact two immiscible or slightly miscible liquids, and may in particular be applied when treating one liquid with another in a washing or extraction process. Either liquid, or both of them may be replaced by a suspension or emulsion, or may consist of a mixture of liquids In washing and extraction processes the com trol of the size of the drops in which one liquid is distributed in the other is of the utmost importance to obtahi the highest possible yield. when injecting one liquid into the other through openings, the size of "the drops depends on the size of the openings and also on the velocity with which the passes through these opening's; this velocity .must be sufficient to ensure that the jet is dispersed into approximately equal drops and or the desired :size. If the velocity of the jet .too low, the drops will be too large, and if it is too high, :a mixture sof'l'large and small drops is formed.

'My invention makes it "possible to obtain in a simple manner a correct drop Iorma'tion throughout the "whole space in which the process "takes place by appropriate control "of the two factors mentioned above. This made clear by the fol- .lowing description, which is further illustrated by means of the drawingsin' whichlrliigures l and '4 :are diagrams of two forms of apparatus in which these principles are applied. Figures 2 and 3 are details of the apparatus shown on Fig. 1. It is understood that the invention is not limited to the embodiments shown in Figs. 1 and 4 but may be modified in any desired way in accordance with the underlying principles.

The apparatus shown on Fig. 1 is a column designed for the treatment of a lighter liquid with a heavier one, moving counter-currently through the column. The heavier, descending liquid enters the column through line 2 and is removed through line 3, while the ascending, lighter liquid is admitted'in through line 4 and removed through line 5. A number of horizontal plates (1), provided with openings and consisting, for instance, of perforated sheet iron, or of metal wire gauze, are fitted and connected one tothe other by means of chains (6) Fromthe bottom of the series of sheets a weight is suspended. Around their circumference, the plates (1) are provided with rims l3 carrying, in a. groove, a packing material (M) for sealing, as shown in Fig. 2. The sealing can also be effected irrother ways, for instance by providing a close fit between the wall of the column and the rims of the plates, which, in order to avoid jamming, are given a rounded shape (Fig. 3). For further sealing, there are shown in Fig. 3 also spiral springs (IS) fitted in grooves. The plates (1) 5 can be moved upwards and downwards by a reciprocating mechanism (8;). It is understood that the perforated plates ('1) may be connected, instead of by chains, by any other means, such for example, as a central movable shaft, and the desired movement oi the system may be effected by means oi any other suitable mechanism, such as .a cam or groove The. operation of the apparatus is as follows: The lliqui'dsa'dmitted through the lines (2) and (I) now through the entire length of the column, :and :each of the "compartments formed by the plates :(19 contains :some of each of these liquids. 'In each of these compartments the heavier liquidisettles toithe bottom, and the lighter ascends 20 to the top, so that there is a layer consisting substantially only of the heavier liquid on the upper side of each perforated plate (1) and a layer consisting substantially only of the lighter liquid on the lower side of each plate. The flow resistance of the perforated plates (1) is great enough to prevent-any appreciable liquid movement through the openings in the plates owing to difference in specific gravity. Assuming that the plates begin to move upwards, while the liq- 3o uid as a whole remains practically stationary, the heavier liquid resting on top of each plate has to pass through the openings in the plate in the form of a rain of jets which are dispersed 35 as drops in the lighter liquid. The velocity 01' these jets in relation to the absolute velocity of the plates is approximately proportional to the ratio between the cross-sectional area of the column and the total area of the plate openings. 40 In this way the heavier liquid is brought into contact in a uniform fine distribution with the lighter one, and the eddy currents which are thus caused intensify still further the washing between the two liquids. I 45 In the subsequent, downward movement of the plates, 9. similar process takes place on the upper side of the plates, this time however, the lighter fluid being injected into the heavier one. It is to be noted that on the side of a plate from which the liquid is driven to the other side, the liquid remains relatively at rest, so that there the separation of the liquids according to the specific gravity can take place practically undisturbed, 55

and in consequence the capacity of the column is equal to that of one without perforated plates.

The process described repeats itself at each plate, so that an intimate contact between the two liquids is effected over the entire length of the column.

The rate of movement of the perforated plates, the length of stroke, the number and size of the openings and the distance between the plates are, of course, determined in each particular case according to circumstances, such as the nature and quantities of the liquids to be treated; in particular the diameter and the number of holes may vary for various levels in the column, so that in each stage of the washing-process the most satisfactory size of drop is obtained. In general, it may be pointed out that in order to obtain the best possible uniformity in the size of drops, it is better to employ small holes and apply a moderate velocity rather than large holes and a high velocity. Further, the total area of the holes in relation to the column cross-section should not be too small, as otherwise anundesirable stress is put on the driving mechanism.

Attention has already been drawn to the use of the rims (8) for sealing. Despite this sealing, however, a certain quantity of liquid always leaks through from one side of the plate to the other, and consequently does not participate in the proc-1 ess of washing, or does so only insufliciently. This quantity has naturally a proportionally larger value in columns of small diameters. In such columns, to avoid leakage losses, the perforated plates may be permanently fixed in the column, and the liquid moved in relation to the plates as shown in Fig. 4. In this construction, the top and bottom of the column are each connected by the lines it and i2, branched off from the inlet and outlet for one of the liquids, to one of the sides of a pump 90, provided with a reciprocating piston. Owing to the movement of the piston, the liquid mass in the column is given a corresponding upward and downward movement, and the same results are obtained as in the apparatus with moving plates.

The apparatus (l0) represented here as a reciprocating pump, may be, of course, replaced by any other device, such as, for instance, a diaphragm pump. With large washing or extraction columns the masses of liquid to be moved according to this system are very large, and in these cases the system with moving plates is preferable, especially as in such cases the ratio of the liquid leaking around the rims to the total amount of liquid is relatively small.

With regard to the perforated plates it may further be pointed out that, as such, metal wire gauze with 1 mm. width of mesh has given satisfactory results in extraction processes. It is preferable to use for this purpose a material which is not readily wetted by the liquids being contacted.

I claim as my invention:

1. In an extraction process the step of bringing into intimate contact two counter flowing relatively immiscible liquids of different specific gravities, by maintaining a body of fluid consisting predominantly of the lighter of said liquids on the lowerside of a perforated plate and a body of liquid consisting predominantly of theheavier of said liquids on the upper side of said perforated plates, and causing said bodies to move alternately in opposite directions through the openings in said perforated plate.

2. An apparatus for bringing relatively immiscible fluids into intimate contact, comprising a vessel with a pair of feed lines communicating with said vessel near the top and bottom, respectively, and a pair of outlet lines communicating with said vessel near the top and bottom, respectively, for the fluids to be contacted, a plurality of perforated plates in said vessel disposed one above the other and transversely to the vertical axis of said vessel and arranged to divide said vessel into a plurality of compartments, a liquid-proof sealing means between the plates and side walls of the vessel, and reciprocating means coacting with said apparatus to cause an oscillatory relative movement between the plates and liquids in said vessel.

3. An apparatus for bringing into intimate contact relatively immiscible liquids, comprising a vertical column provided with a pair of feed lines communicating with said column near the top and bottom, respectively, and a pair of outlet lines communicating with said column near the top and bottom, respectively, for the liquids to be contacted, a plurality of perforated plates arranged one above the other and within the column transversely to its vertical axis, and adapted for vertical movement, a liquid-proof sealingmeans between the plates and side walls of the column, and mechanism for imparting a vertical reciprocating motion to at least some of said plates.

4. The apparatus according to claim 3in which the perforated movable plates are suspended over each other by tension members.

5. The apparatus according to claim 3 in which the upper movable perforated plate is connected to the reciprocating mechanism by a tension member, the other movable plates are suspended below said upper plates by flexible tension mem bers, and a weight is attached to the lowest movable plate.

WILLEM JOHANNES DOMDIICUS VAN DIJCK.

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