US2446717A - Method and means for destroying froth - Google Patents

Description

Aug. 10, 1948. J. o. NAUCLER 2,446,717

METHOD AND MEANS FOR DESTROYING-FROTH Filed June 16, 1944 2 Sheets-Sheet l I Johan O/of Mu e er J. o. NAUCLER Q 2,446,717

METHOD AND MEANS FOR DESTROYING-FROTH Filed June 16, 1944 2 Sheets-Sheet 2 O/of Nauc/er Patented Aug. 10, 1948 UNITED IWETHOD AND MEAN S FOR DESTROYING TH Johan Olof Nauclr, Stocksund, Sweden Application June 16, 1944, Serial No. 540,715 In Sweden July 10, 1943 9 Claims.

The present invention relates to a method and apparatus for destroying or quenching froth and refers more particularly to the destruction of froth from liquids containing substances having a high or relatively high activity as to surface tension.

It is an object of this invention to obtain an eflicient and rapid destruction of the froth by relatively cheap and simple means. A further object is to make possible by rotary means to quench froth by spreading it out and without passing it through narrow circuits. A still further object is to effect the spreading of the froth and its transport to the place of spreading out by common means.

To obtain these and other objects which will be evident through the following description I suggest to bring the froth to be quenched into contact with a, rotating body so as to impart to the froth mass centrifugal forces which will cause the froth mass to be spread out in the form of a diverging layer into the surrounding atmosphere with the effect that the froth bubbles will burst and coalesce into drops.

In a suitable device for carrying this method into practice a plate or disc or bowl is rotatable about its axis. The froth may be supplied to the centre of this rotatable member from below or from above.

The invention will now be explained with reference to the accompanying drawings but it is to be understood that it will not be limited thereby as to its scope. In the drawings Figure 1 shows a. device having a horizontally placed disc, Figure 2 shows a truncated cone embodiment, Figure 3 is a vertical cross-section through an embodiment having a. number of vertical discs, Figure 4 is a horizontal section through the device shown in Figure 3 and Figure 5 illustrates a froth quencher applied in a soap recovering device.

Figure 1 illustrates a suitable device of this kind. It consists of a plate I, rotatable about its axis by means of a motor 2 and the shaft 3. The shaft is preferably supported by the bearings 4 and 5. The froth is supplied to the plate, preferably to the center thereof, through the pipe 5 and the screen 1. By the friction between the plate and the froth mass a rotation is imparted to the froth throwing it out into the ambient atmosphere, where it is to a great extent transformed into liquid drops. These are caught by the screen 8 which is here vertically disposed but may, if found suitable, be given a certain inclination, for instance more or less adapted to the 2 direction of movement of the liquid drops, so as tocounteract new froth formation.

The plate may also with advantage be hollow or concave and/or be provided with vanes for the froth mass. It may, if desired, be provided with an opening or openings in the centre and thus be more or less annular.

From the screen 8 the liquid drops fall down into the collecting vessel 9, from which the quenched froth may be removed as liquid. Gas escaping from the froth quencher leaves the apparatus between the plate I and the screen 8.

The gas, which in certain cases may remain in the liquid or may be introduced into it, for instance, when the drops are caught by the screen 8, forms gradually a new froth, which accumulates on the surface of the liquid in the vessel 9. This froth generally constituting only a minute part of the froth mass originally supplied to the froth quenching device may preferably be quenched in the same apparatus. For this purpose it must, however, by means of a special device, for instance a selfsucking pump, be forwarded from the level of the froth mass in the vessel 9 up to the rotating plate.

In case the plate is made with a greater extension in the vertical direction, for instance, as a frustum of a cone, as will be seen from Figure 2, such a pump may be superfluous, which is a great advantage, since the pumps which have to be used are often unproportionately great.

In Figure 2 numeral l indicates a frustum of a cone, for instance of sheet, which by means of a motor device 2 and the shaft 3 is made to rotate about its axis. The shaft is preferably supported by the bearings 4 and 5. The froth is supplied to the vessel 9 through the pipe 6. The vessel 9 may be that vessel in which the froth is formed.

When the froth surface in the vessel 9 reaches the lower edge of the rotary cone I, the parts of the froth mass nearest to the cone surface are carried away with the rotation through the friction. The rotation imparts to these parts of the froth mass centrifugal forces which cause the froth mass to be brought up along the inner side of the cone until they reach the edge where they are thrown out. Through the extension of the froth film arising along the surface of the cone and particularly in the space between the edge of the cone and the screen 8, this film is transformed into drops, which are then caught by the screen and fall down into the vessel 9. The froth which eventually may remain after the screen is separated in the vessel 9, where it is automatically brought to the bulk of froth to be quenched.

A device according to Figure 2 may consequently within certain limits keep the amount of froth constant in a vessel.

According to the special use of the apparatus the vessel 9 will be given a special form and construction in detail adapted to said use.

Thus, for instance, it can be given the form of a classifier, i. e. a kind of separator as to grain size that is Well known to those skilled in the art, in case the froth contains suspended therein solid particles heavier (having a greater specific gravity) than the liquid portion of the froth. Such a kind of froth will be met with in the flotation of minerals.

If the froth mass contains in addition to gas and liquid any other constituent which is accumulated therein, as is the case, for instance, with the sulphate soap of sulphate cellulose lye (black liquor), the vessel 9 is preferably made as a florentine bottle where the soap may run off above the lye outlet.

If it is desired to lift the froth higher than is suitably possible with only a cone the latter may in its lower end be elongated and provided with a propeller or the like which feeds the froth up to the cone.

It is in certain cases also possible and advantageous to use for the froth quenching device plane plates but nevertheless attain the simultaneous pumpin effect desired. This may, it is true, he

done analogously with the case of the cone by providing the plate in the centre with a screw or propeller which submerges into the froth mass but it may also be performed in such a manner that the shaft of the plate is placed sloping or horizontal and the plate is disposed in such a level in relation to the froth surface that it is partly submerged into the froth.

It is particularly suitable to arrange the shaft horizontally. It is then possible to attach a plurality of plates on the same shaft whereby a high capacity may be attained by small devices.

Such a device is shown in the Figures 3 and 4.

In these figures II is a shaft carrying a number of plates I 2, which are partly submerged into the froth mass M contained in the vessel [3. At the rotation of the plates the froth is brought along due to the friction and spread into the atmosphere between the plates l2 and the screen plates I5v and l 6. It is then transformed into drops which are caught by the screen plates. The froth is supplied to the quenching device through the pipe H. The gas escapes through the interspace l8 between the screen plates l5 and I6. At its lower end the screen plate I6 here acts as a froth trap, so that only gas free liquid flows off through the overflow IS, the height of which should preferably be regulatable when required.

The bulk of froth may, if desired, be poured onto the rotating plates, for instance, on the part moving upwards.

As will be seen from Figure 4 the plates may preferably have somewhat different diameters, which contributes to a more even load and a better effect, since the toughest froth generally requires greater peripheral rapidity of the plates for an effective quenching.

Suitable peripheral rapidities of the rotating plates and cones are generally 10 to 50 meters per second, preferably to 30 meters per second. The diameters should in this case be between and 60 centimeters, preferably between and 50, e. g. to centimeters.

The cones are preferably given a height of to 400 millimeters, the apex angle exceeding 20".

An example of recovering and separating soap in the manufacture of sulphate pulp is shown in Figure 5. The black liquor froth runs down into the vessel 2| and is forwarded by the propeller 22 up to the rotating cone 23 rotated by the motor 24. The stationary pipe 25 and the stationary cone 26 serve as casing or jacket round the propeller and as tightening for the rotating cone 23. The froth is thrown from the cone out against the screen 21 and flows out into the box 28, where the liquor sinks to the bottom and is led off through the liquid trap 29 and the pipe 30 to the vessel 3|, from where it is pumped off by the pump 32. The liquid trap is provided with an air-tube 33. The soap flows above the liquor and runs off over the bridge 34 to the vessel 35 from where it is led, for instance, to a resin boilery through the tube 36 and the pump 37. The froth and the soap may also be carried back to the froth quenching through an opening 38 and the channel 39.

I claim:

1. A method for destroying or quenching froth, characterized in disposing a solid body having an opening therethrough along one axis, said opening being narrower at the one end than at the other, with said narrower end lowermost, submerging said narrower end into the bulk of froth, subjecting said body to rotation about said axis, passing said froth by said rotation upwards in said openin to the wider end of said body, said rotation being such as to cause said froth to be spread out from said body in the form of a relatively thin layer into the surrounding atmosphere, said rotation taking place with so great a distance between said body and other solid bodies in at least most of the directions of said spreading out that the transformation of froth into liquid will be substantially accomplished while the froth is still suspended in said atmosphere.

2. A method for destroying or quenching froth, characterized in disposing a solid body having an opening therethrough along one axis said opening being narrower at the one end than at the other, with said narrower end lowermost, submerging said narrower end into the bulk of froth, subjecting said body to rotation about said axis, passing said froth by said rotation upwards in said opening, the speed of said rotation being such as to cause said froth to be spread out in the form of a relatively thin layer into the surrounding atmosphere, said rotation taking place with so great a distance between said body and other stationary solid bodies in at least most of the directions of said spreading out that the transformation of froth into liquid will be substantially accomplished while the froth is still suspended in said atmosphere.

3. A method for destroying or quenching froth. characterized in disposing a solid body having an opening therethrough, at least the upper portion of said opening having substantially the shape of a frustum of a cone tapering downwards, with the wide end of said opening upwards, subjecting said body to rotation about the aXis of said opening, whereby to pass said froth upwards through said opening, said rotation being such as to spread said froth out into the surrounding atmosphere to such distance from said body and other solid bodies that the transformation of froth into liquid will be substantially accomplished while the froth is still suspendedin said atmosphere.

4. Apparatus for destroying or quenching froth comprising a stationary funnel-like casing, in the tapering upper portion of said casing a rotary hollow member, the cavity of which tapers downwards, and in the cylindrical lower portion of said casing a propelling means adapted by rotation to feed upwards.

5. Apparatus for destroying or quenching froth comprising a hollow body, the cavity of said body tapering from one side of said body, said body being rotatable about the axis of said cavity, means for supplying froth to the small end of said tapered cavity, propelling means connected to said froth supply means, said body at the wide end of said cavity being spaced from other solid bodies in at least most of the substantially radial directions.

6. Apparatus for destroying or quenching froth comprising a hollow body, the cavity of said body tapering from one side of said body, said body being rotatable about the axis of said body, a stationary jacket spaced from but closely encasing said hollow body, means for supplying froth to the small end of said tapering cavity, said body at the wide end of said cavity being spaced from other solid bodies in at least most of the substantially radial directions.

7. A method for destroying or quenching froth characterized in rotating a solid body having an opening therethrough' along its axis of rotation, said opening being narrower at one end than at the other, supplying froth to the narrow end, said body being rotated at such speeds of rotation as to cause the froth to be spread out in the form of a successively attenuating layer, the distance between the rotating body and other solid, stationary bodies in at least most of the directions of the spreading out being so great relative to the speed of rotation of the rotating body that the froth will be substantially transformed into liquid before reaching the stationary solid bodies.

8. A method for destroying or quenching froth characterized in disposing a solid body having an opening therethrough along one axis, said opening being narrower at the one end than at the other, with said narrow end lowermost, submerging said narrower end into the bulk of froth, subjecting said body to rotation about said axis, passing said froth by said rotation upwards in said opening to the wider end of said body, said rotation being such as to cause said froth to be spread out in the form of a successively attenuating layer so that the foam bubbles will burst by stretching and form liquid particles, said rotation taking place with so great a distance between said body and other solid bodies in at least most of the directions of said spreading out that the transformation of froth into liquid will be substantially accomplished before the froth may reach the other solid bodies.

9. A method for destroying or quenching froth characterized in rotating a solid body having a cavity therein along its aXis of rotation, said cavity being narrower at its lower end than at the upper end and having a peripherally continuous, unobstructed wall defining its wider upper end, supplying froth in such a manner that the froth first contacts the rotating body adjacent the narrower lower end of said cavity, said body being rotated at such speeds of rotation as to cause the froth to be spread out in the form of a successively attenuating layer, the distance between the rotating body and other solid, stationary bodies in at least most of the directions of the spreading out being so great relative to the speed of rotation of the rotating body that the froth will be substantially transformed into liquid before reaching the stationary solid bodies.

JOHAN OLOF NAUCLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 940,103 Feld Nov. 16, 1909 1,376,073 Borcherdt Apr. 26, 1921 1,609,413 Kristofferson Dec. 7, 1926 1,796,982 Cutler Mar. 17, 1931 1,967,938 Jantzen et al. July 24, 1934 2,070,453 Rodman Feb. 9, 1937 2,163,474 Sloan June 20, 1939 2,335,641 Buckley Nov. 30, 1943 2,401,469 Edwards June 4, 1946 FOREIGN PATENTS Number Country Date 262,032 Germany July 5, 1913 14,181 Netherlands Feb. 15, 1926

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