EP0288338B1 - Device for increasing the speed and the energy of the particles of a liquid-jet, and its use, especially in the sugar industry - Google Patents

Description

The present invention relates to a device for increasing the speed and energy of projection of the particles of a liquid jet and its application in particular in the sugar industry.

The speed and energy of projection of the particles of liquid jets are sometimes insufficient for the desired result, this insufficiency often being due to technological limitations linked to the devices used to generate such jets, whether these are jets of liquid sprayed or not.

Document EP-A 0 023 980 describes a sandblasting device using a rotating wheel to accelerate and deflect a jet of a fluid.

However, the invention aims precisely to bring the energy level of a given jet, whatever it is, to a higher level thanks to a device essentially characterized by the fact that it consists of a cylinder mounted to rotate around the axis parallel to its generatrices and placed so as to receive during its rotation and on its external peripheral surface the jet (s) of which it is desired to increase the speed and the energy of the particles.

Of course, the desired result is obtained according to the invention, whether the means for obtaining a jet of liquid is of the nozzle or nozzle type, in the case of sprayed liquid, or even a simple hole made in a pressurized liquid, otherwise. Likewise, the jet of liquid can be directed orthogonally or obliquely onto the surface of the moving cylinder. The source of the jet can also be fixed or mobile and the jet itself can have a conical shape or be a flat jet.

Those skilled in the art will readily understand that the rotating cylinder communicates part of its energy to the drops of liquid which it receives and returns them outwards with an increased speed, this speed being all the more important as the peripheral speed of this cylinder is high.

• - la figure 1 est un schéma illustrant le dispositif selon l'invention ;
• - la figure 2 est un schéma illustrant une essoreuse-centrifugeuse de l'industrie sucrière ;
• - et la figure 3 est un schéma analogue à celui de la figure 2 illustrant l'application de l'invention.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows, given with reference to the appended drawings in which:

• - Figure 1 is a diagram illustrating the device according to the invention;
• - Figure 2 is a diagram illustrating a centrifugal wringer in the sugar industry;
• - And Figure 3 is a diagram similar to that of Figure 2 illustrating the application of the invention.

Referring to Figure 1, the device according to the invention comprises a cylinder 1 rotatably mounted around its major axis XY and placed opposite at least one nozzle 2 (or other similar means) generating a jet 3 of liquid (sprayed or not), so as to receive this jet on its peripheral surface, which jet will be returned by this surface in the form of a new jet 4 whose particles will be driven at a speed greater than that of the incident particles of the jet 3. Of course, as indicated above, this new speed will be all the more important the higher the peripheral speed of the cylinder 1.

In addition, the speed of the particles or drops of liquid being increased, their energy will also be increased, taking into account the fact that it is well known that the kinetic energy of a moving body is proportional to the square of its speed.

This invention finds a particularly interesting application in the sugar industry. It is known in fact that in a sugar refinery, the crystallized sugar is separated from its mother liquor in centrifugal dryers operating batchwise.

A typical cycle specific to this industry includes the start-up of the centrifuge, its loading in mass, the acceleration of the rotation of the "basket" of the machine, the operations of clearing the sugar contained in the basket with water and / or steam, stopping the machine and draining its sugar. Each cycle lasts a few minutes.

The crystallization mother liquor that separates from the sugar is viscous, since it still contains a lot of sugar and the other "non-sugar" materials. In the profession, this mother liquor is called "poor taste".

On the other hand, what is called "rich sewer" is constituted by the liquid obtained at the end of the spinning operation by clearing the sugar with water and steam. These clearings clean the sugar by ridding it of the residual mother liquor; moreover, they solubilize sugar which was crystallized. We usually separate "rich sewers" from "poor sewers"; the "rich sewers" from the sugar melted in the clearing water are generally recycled, while the "poor sewers" are treated separately.

The "poor" and "rich" sewers descend along the wall of the fixed skirt surrounding the basket.

The diagram in Figure 2 attached illustrates this operational phase of the sugar industry. In this figure, the reference M designates the motor driving in rotation the basket 1 a of a centrifuge-centrifuge with its fixed skirt 2a ending in its discharge pipe for "sewers" E. The ramp for clearing with water is designated by the reference R with its nozzle devices or nozzles 5.

In practice, the separation of "rich sewers" from "poor sewers" is difficult to achieve. Indeed, it is found that part of the "poor sewer" which has been projected by the rotation of the basket 1a on the internal face of the fixed skirt 2a still adheres to it at the time of clearings.

We know that this fraction of "poor sewer" will take a long time to flow due to its viscosity. It will be driven by subsequent clearings and will pollute the "rich sewers".

We then obtain a partial recovery of these two sewers with the consequence that their separation will always be a compromise, each sewer containing more or less of the other sewer.

The present invention can remedy this state of affairs in this sense, that applied to the centrifuge device mentioned above, the system according to the invention makes it possible to clean the residues "of poor sewers", while avoiding their pollution by "rich sewers".

The present invention will find its best application by placing on the skirt 2a and inside of the latter a series of nozzles 6 propelling jets of water sprayed or not on the external face of the basket 1 a of a centrifuge of the type described above, these jets being oriented and distributed so as to sprinkle the entire surface external of this basket.

According to an advantageous operating mode, the usual rotation cycle of said basket is modified by making, before practicing the clearings, a short injection of water sprayed by these nozzles or nozzles 6. This sprayed water is discharged at high speed through the basket 1a in rotation and it strikes the internal face of the skirt 2a. The "poor sewer" from the immediately preceding centrifugation operation is thus diluted quickly, the water mixing intimately with the "poor sewer" thanks to the kinetic energy of the jets in question, which facilitates its flow by the discharge pipe E. The internal face of the skirt 2a is thus washed with a minimum quantity of water which will therefore be directed to the "poor sewers".

Thus, thanks to the present invention, it is possible to improve the separation of "poor sewers" and "rich sewers", the "poor sewers" being poorer, because they are not enriched in "rich sewer" and the "rich sewers" being richer, since they contain less "poor sewer".

The “rich sewers” being thus less polluted, one notes then a expenditure of water of clearing lower than by the usual technique.

Indeed, these improvements have important consequences on the quality of the products, on the yield and the throughput of the crystallization workshop because they are passed on gradually from the concentration of the cooked mass to each of the products from the making.

It is understood that this is only an example and that the system according to the invention is applicable to any industry using the principle of solid-liquid separation by centrifugation, in all cases where there is a need to clean the fixed skirt.

Claims (2)

1. Device for increasing the speed and the energy of the particles of a liquid-jet, with a view to using this energy to clean a wall, characterised in that it consists of a device producing the liquid-jet (2) and a cylinder (1) mounted so that it can rotate about the axis parallel to its generatrices, and positioned in such a way that as it rotates it receives on its external periphery the jet or jets the speed and the energy of the particles of which are to be increased.

2. Use of the device according to claim 1 in the sugar industry, according to which one or more jets of water (6) are sprayed on to the external periphery of the basket (1a) of a centrifuge, said jet or jets (6) being directed and distributed along the internal periphery of the fixed skirt (2a) of the said centrifuge.

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