EP0613725A2

EP0613725A2 - Flotation device with foam sucking means

Info

Publication number: EP0613725A2
Application number: EP94200443A
Authority: EP
Inventors: Antonio Velo
Original assignee: Velo SpA
Current assignee: Velo SpA
Priority date: 1993-02-25
Filing date: 1994-02-22
Publication date: 1994-09-07
Also published as: ITPD930017U1; ITPD930017V0; IT231090Y1; EP0613725A3

Abstract

A flotation device for the suction of floated masses comprising a first inner tub (12) vertically arranged and communicating at the bottom with a second outer tub (26) which surrounds the first tub (12) and operates as a manifold for clarified liquid, the second tub communicating with a collector resevoir (34) for clarified liquid. At the middle of the first tub (12), the flotation device bears a column (40) extending above an upper edge of the inner tub (12) and sustaining a support (42) for a motorized arm (50) which can be oriented and ending with a suction hood (54) which can also be oriented by driving means (66) arranged on the arm (50); the column (40), the arm (50) and the suction hood (50) being hollow, connected among them and to a pipe (68) for the draining of floated particles. The pipe (68) is connected to a reverseble volumetric pump (70) which provides both for the removal of the floated particles and for the inlet of washing water in order to carry out periodic cleaning of the same flotation device.

Description

The present invention relates to a flotation device for continously separating solid particles suspended in liquids, especially alimentary liquids, in order to proceed with their clarification.
The clarification of a liquid may occur by some methods: that is for decantation, filtration, centrifugation and flotation.
Among all the above-mentioned methods, the flotation is one among the most practical, cheap and well suitable ones for a continuos processing of large liquid masses.
Said flotation process consists in separating solid particles from liquid by floating, making transport said particles by gaseous bubbles which are adhered to them.
As hereinbefore stated, this process is ideal for a continuos processing because it is possible to put continuously into a tub-like vessel a liquid containing solid particles, to which a gas has been added, to have the solid particles transported by the gas and come to the surface and to separate, always in a continuos manner, the floating mass from the liquid mass purified of the particles.
However, it is known that, several times, the solid particles suspended in substances to be floated, mainly all alimentary liquids, are so small that practically they are not able to conglobate therein the necessary gas in order to permit the flotation process. Consequently, coadjuvant substances which have the purpose of thickening and then increasing in size such particles are added. Typical coadjuvant substances are: gelatine, silicon dioxide in colloidal suspension, bentonite and the like.
In order to make the particles, added to the coadjuvant substances, float in size the flotation tub, in a pressurized reactor floating gases, like nitrogen, air or oxygen, and also coadjuvant agents, are added to the liquid mass to be processed, agents that, adhering as bubbles to the increased solid particles, permit them to float in said flotation tub.
At this point it is enough to remove the floating solid particles, assembled as a foam, to obtain a greatly clarified liquid in a continously operating process.
In the present floating systems the removal of the solid particles is done in different ways which are all comprised of mechanical systems going from simple skimmer shovels to rotary gatherers.
However, the skimmer shovels, if they are of a very simple kind, have the drawback to require the attention or, at least, a close supervision with operating staff in order to keep the shovels always at a such level which assure a proper drawing of the foam from the flotation tub unless they are provided with complicated means taking into account and follow the level of the floated liquid within the tub. On the contrary, the rotary gatherers have, in addition to a considerable complexity and consequent cost, the risk, if operated very fast, to scatter the foam with considerable problems of hygiene, safety and maintenance.
It is an object of the present invention to modify the system removing the foam which contains solid particles so that the removal may occur in a simple, easy and cheap way excluding or minimizing any human intervention during the same flotation process.
The above-mentioned object is achieved by a flotation device which provides to suck the floated foam floating over a liquid mass in clarification within a first tub by means of an exhauster dipped into the foam mass, but not reaching the liquid, moving above said foam mass in order to cover all its surface and, consequently, to remove in a substantially uniform way the foam from the top of the flotation device.
In particular, the first tub is circular and the exhauster is fixed to a radial arm which is pivotted substantially at the middle of the tub and circularly moves in order to cover all the upper surface of the tub itself.
Preferably, said radial arm is fastened to a rotary support which is positioned at the center of the tub, moved by driving means and installed on a substantially vertical column which is fastened to the bottom of the tub itself. Obviously, said driving means may be installed either over or under the column.
More preferably, the radial arm outwardly ends with a pipe-fitting movable about the axis of the same arm carrying a suction hood may be oriented in such a way that it turns a suction inlet opening thereof either towards the foam mass, when it is intended to suck the same, or towards an inner wall of the first tub when it is intended to carry out a washing of the tub itself.
Particularly, the above-mentioned movable pipe-fitting is moved by a motor providing to orient the suction hood so that it turns towards the bottom or the side-wall of said first tub depending on whether it is required to suck the foam or to wash the tub of the flotation device.
Furthermore, the movable pipe-fitting may be moved with more carefull movements to get the suction hood to reach the dipping depth within the floating foam mass.
Alternatively, the suction hood may be manually manoeuvred in order to be fixed to the position requested to carry out the required task, that is the suction of the foam at a controlled depth or the washing of the tub.
In order to practically carry out the washing of the first tub, it is advisable to connect the exhaust pipe of the floating foam to a washing water reserve or source, to invert the movement of a metering pump in order to put said washing water into the movable arm and into the exhaust hood and, while the washing water goes out against the tub walls, rotates the movable arm in order to carry out repeated washings of the same walls.
Moreover, the tub must be provided with a bottom drain for the removal of the washing water and of every residue trailed thereby.
The features of the present invention will clearly appear from the claims forming the conclusive part of the present description. However, other features and benefits thereof might be appreciated from the following detailed description of a non-limiting embodiment thereof provided with the enclosed figures, wherein:

figure 1 is a cross-section side view of a working flotation device according to the present invention while removes foam by suction;
figure 2 is a cross-section side view of the suction hood used in the present flotation device; and
figure 3 is a cross-section front view of the suction hood itself.

Referring to figure 1, the flotation device 10 according to the invention consists of a first inner tub 12, substantially cylindrical and formed by a peripherical wall 14 which is suspended above a bottom 16 which is lowered in the middle and provided with an anular opening 18 for the entering of liquid to be clarified, being said opening connected to a pipe 20 for the supply of the liquid itself and surrounded by a relieved crown 22 having the task to upwardly direct the liquid flow to be clarified so that the liquid remains away from the peripheric wall 14.
Then, the area delimited by the crown 22 is partially closed upwards by a flange 25 delimiting a ring-shaped opening 27 which allows to keep the flow of the liquid to be clarified away from the center of the inner tub 12 and from its peripheric wall 14. The bottom 16 is joined with a cylindrical peripheric wall 24 defining a second outer tub 26 which forms with the first tub 12 an hollow space 28 in which passes through a space 23 the clarified liquid which has left the solid particles floated by the gas as a foam mass 30 at the tub top 12. The clarified liquid within the hollow space 28 rises and pours, by means of a pipe 32, into a collector reservoir 34 from which it may proceed through a pipe 36 towards the destination of the clarified liquid (conservation, fermentation or packaging).
Looking at the drawing portion of the mass 30 of floated foam, it is seen that it consists of a hollow column 40 operating both as a drain-pipe of the foam or as a stand for a rotary support 42 rotated by a motor 44 through a suitable mechanical shafting unit 46 of a kind well known in the art, rotating in the direction of an arrow 48. From the rotary support 42 projects a pipe-like arm 50 which by means of a pipe-fitting 52, is joined to a suction hood 54 that, from figures 2 and 3 appears consisted of two divergent walls 56a and 56b arranged in a radial direction with respect to the tub 12, of two convergent walls 56a and 56b transversally arranged with respect to the first two walls and of a sleeve 60 for the connection to the pipe-fitting 52. The pipe-fitting 52 is made in such a way to be threaded in the arm 50 and to rotate therein and furthermore, the pipe-fitting has, at one end, a toothed crown 62 engaged in a pinion 64 coming from a motor 66, fastened to the arm 50 and the rotation thereof controls the orientation of the hood 54 with respect to the tub 12.
The pipe, comprised of the hollow column 40, comes out under the bottom 16 as a pipe 68 for the draining of the foam which, by means of a volumetric pump 70, removing the foam from the flotation device 10 through a further pipe 72.
At last, a drain outlet 74, placed under the lowered bottom 16 in the middle thereof, just out of the crown 22, is used, during the washing of the flotation device 10, for drawing and draining the washing water. This drain outled 74 ends with a controlled valve 76 which must be opened when it is required to drain the water with which the washing of the flotation device itself has been carried out.
The operation of the device is the following.
When the clarification of a liquid, especially an alimentary liquid, like must, juice or other is required, a liquid to be clarified is put into the tub 12, through the pipe 20, filling completely the tub.
The liquid to be clarified, containing the thickeners and the flotation gas which is dispersed as a plurality of bubbles, forms an abundant foamy mass 30 at the surface from which it may be gathered and removed by the suction hood 54. In the meanwhile, the clarified liquid passes through a space 23 and goes into the hollow space 28 which is formed between the wall 14 of the tub 12 and the wall 24 of the second tub 26. From this point the liquid rises up to reach the pipe 32 and pours into the reservoir 34 and from this, by means of the pipe 36, proceeds to the other equipments of the plant.
In conclusion, there are contemporaneously and continously: the inlet of liquid to be clarified through the pipe 20, the outlet of clarified liquid through the pipe 32 and the removal of foam containing the particles which have been removed by suction by means of the hood 54. So, the sucked foam proceeds into the pipe of the column 40 and then, through the pipe 68, comes to the volumetric pump 70 which at last conveys the foam into the drain pipe 72.
The operating of this flotation device 10 proceeds until there is liquid to be clarified supplied through the pipe 20.
As the flotation process ends, it is possible to completely clean the flotation device 10 simply connecting the drain pipe 72 to a water source or reserve and inverting the operation of the volumetric pump 70 so as to supply washing water under pressure to the hood 54 which, under the present occurence, becomes a sprayer. The same hood 54 is oriented by an appropriate control signal to the positioning motor 66 or by means of a manual manoeuvre in order to point towards the wall 14 of the inner tub 12 so that the spray coming out from the hood 54, hits the wall 14 and at last gathers on the lowered bottom 16 moves all the present residues of both liquid and foam, also diluting possible bottom sludges 78 due to collection of not floated particles 80 falling towards the bottom. At this point, the opening of the valve 76 of the drain outlet 74 removes the washing water together with all the residues permitting a complete cleaning of the flotation device.
What it has hereinbefore been disclosed is an embodiment of the present invention and from the reading of the previous description obvious and equivalent approaches, which might be devised by those skilled in this particular art are to be considered all here covered. For example, instead of providing a suitable drain outlet 74 for the washing water, it might be used the same pipe 20 for supply the liquid to be clarified simply disconnecting it from the source of said liquid and connecting the same to a drain of the washing water. Then, the positioner motor 66, the pinion 64 and the toothed crown 62 on the pipe-fitting 52 might be all omitted and the orientation of the hood 54 might be carried out manually because the adjustment of the dipping depth of the hood 54 into the foamy mass 30 is usually done once for all when the flotation process begins and the whashing of the flotation device is carried out only when ends the process usually lasting several hours.

Claims

Flotation device by suction which provides to suck the floated foam (30) floating over a liquid mass in clarification within a first tub (12) characterized by an exhauster dipped into the foam mass (30), but not reaching the liquid, moving above said foam mass (30) in order to cover all its surface and, consequently, to remove in a substantially uniform way the foam from the top of the flotation device.
Flotation device according to the claim 1, characterized in that the first tub (12) is circular and the exhauster fan (54) is fixed to a radial arm (50) which is pivotted substantially at the middle of the tub (12) and circularly moves in order to cover all the upper surface of the tub (12) itself.
Flotation device according to the claim 2, characterized in that the radial arm (50) is fastened to a rotary support (42) which is positioned at the center of the tub (12), moved by driving means (44) and installed over a substantially vertical column (40) which is fastened to the bottom (16) of the same tub (12).
Flotation device according to the claim 3, characterized in that said driving means (44) are fixed over the rotary support (42).
Flotation device according to the claim 3, characterized in that said driving means (44) are placed under the column (40) and therefore under the bottom (16) of the tub (12).
Flotation device according to the claims 3 to 5, characterized in that the radial arm (50) outwardly ends with a pipe-fitting (52) which movable about the axis of the same arm (50) carring a suction hood (54) whish may be oriented in such a way that it turns a suction inlet opening thereof either towards the foam mass (30), when it is intended to suck the same, or towards an inner wall (14) of the first tub (12) when it is intended to carry out a washing of the tub (12) itself.
Flotation device according to the claim 6, characterized in that the above-mentioned movable pipe-fitting (52) is moved by a motor (66) providing to orient the suction hood (54) so that it turns towards the bottom (16) or the side-wall (14) of said first tub (12) depending on whether it is required to suck the foam (30) or to wash the tub (12) of the flotation device.
Flotation device according to the claim 7, characterized in that the movable pipe-fitting (54) may be moved with more careful movements to get the suction hood (54) to reach the dipping depth within the floating foam mass (30).
Flotation device according to the claim 6, characterized in that the suction hood (54) may be manually manoeuvred in order to be fixed to the position requested to carry out the required task, that is the suction of the foam (30) at a controlled depth or the washing of the tub (12).
Flotation device according to the preceding claims, characterized in that in order to practically carry out the washing of the first tub (12), it is advisable to connect the exhaust pipe (72) of the floating foam (30) to a washing water reserve or source, to invert the movement of a metering pump (70) in order to put said washing water into the movable arm (50) and into the exhaust hood (54) and, while the washing water goes out against the walls (14) of the tub (12), rotates the movable arm (50) in order to carry out repeated washings of the same walls (14).
Flotation device according to the claim 10, characterized in that the tub (12) must be provided with a bottom drain (74) for the removal of the washing water and of every residue trailed thereby.