US2010902A - Process and apparatus for converting liquid substances into the form of granules - Google Patents

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I Aug. 13, 1935. STEPHANSEN 2,010,902

PROCESS AND APPARATUS FOR CONVERTING LIQUID SUBSTANCES INTO THE FORM OF GRANULES Filed June 10, 1953 .Elg l III/III Patented Aug. 13, 1935 UNITED STATES PROCESS AND APPARATUS FOR CONVERT- ING LIQUID SUBSTANCES INTO THE FORM OF GRANULES Nicolai Stephansen, Oslo, Norway, assignor to Norsk Hydro-Elektrisk Kvaelstofaktieselskab,

Oslo, Norway Application June 10, 1933, Serial No. 675,187 In Norway October 1'7, 1932 3 Claims.

My invention relates to a process and an apparatus for the treatment of liquid substances as melts, solutions,- emulsions or pulpy masses for the purpose of solidifying the same and converting them into the form of granules.

Among the various kinds of apparatus used for converting liquid substances into the form of granules, rotating discs have been employed with or without combination with heating means. By conducting the substances down on to .a quickly rotating disc in the near vicinity of its centre, the substance is flung outwards, the water evaporated and the mass converted into a more or less pulverized form, all according to the 15 speed of rotation of the disc and the viscosity, quantity etc. of the substance. For instance, by this method mill; can be concentrated to a powder (dry milk) or concentrated salt solutions can be converted into solid substances, .say niirate of lime or other materials.

When this method is to be used for producing ers in granular form, the problem arises c ise large plants and apparatus capable of g hundreds of thousands of tons per are. It is then either necessary to malre use a great number of separate machines, or to everal discs on one axle. As each of the est have its separate supply of solutions d salt, the apparatus becomes very coms nce whereby it possible in one and the same apparatus to obtain a manifold increase in I yield. The invention also aims at constructsuitable apparatus for carrying out the treatment, liquid substances in the form for in- 48 stance of a pulpy mass are spread over a rotatin; disc, so that the substance thereby gradual- 13; becomes converted into a very thin layer, the centrifugal iorce (rapidly increasing with the distance from the centre of the disc) wi l cause 45 the layer or film formed to be broken up and so the mass becomes caked before it leaves the disc. The aim. of the present invention is to prevent this. For this purpose I cause the film or flowing mass to be divided into two separate parts 7 53 at a suitable distance from the centre of the disc, it being as shall hereafter be more precisely described, thereby possible to reduce the distance through which the layer must pass before it leaves the apparatus, while at the same time obtaining a layer or the necessary thinness.

More specifically described the process consists in dividing the film or flowing mass at a suitable distance from the centre of the disc into rays, so that outside of this point the mass is directed in two separate parts to another rotating part of the machine. These rays spread over the rotating surfaces forming, before the mass leaves the disc, two separate films of a thickness corresponding to the peripheral speed which is suitable for the formation of an even product. 10

The process as above indicated will be fully understood by the description below the two forms of apparatus for carrying out the process.

Fig. l is a diagrammatic axial section of the simplest form of apparatus.

Fig. 2 a similar drawing of a more complete apparatus.

Fig. 3 is a perspective view of a part of Fig. 1 on an enlarged scale, illustrating the manner in which the him of liquid material is divided in two 09 sets of rays and thereupon led to form two separate films.

Figure 4- is a sectional view of the apparatus shown in Figure 1 showing the means for heating the working surfaces.

In Fig. 1', A represents a driving shaft on which is fixed a central disc 33, shaped like a plate. Surrounding this is a larger disc C, which in cross section has the shape of two cones united by a rounded portion as shown on the drawing and rotating with the central disc. On this outer disc blades or shovels E, which alternatively lead to the upper and the lower part, are formed pointing towards the plate or disc B (see also Fig. 3) The substance which is to be dried and granulated is conducted through pipe D down on the disc B. On account of the centrifugal force, the mass is hung into the blades E on the outer disc and the film is thereby cut into rays (F, Fig. 3), which is alternately conducted on the upper and lower surface of the disc C. These rays will spread on the surfaces of the disc C, and as they are getting thinner, they will unite and form a continuous film before they reach the edge of the disc, which latter they will leave in the form of powder or granules. Fig.3 is seen from the axis of the apparatus a little distance above the central disc B.

G indicates a vertical, circular section of the film just before hitting the blades E.

By giving the surfaces of the disc 0 a more or less conical shape they will render more or less resistance against the action of the centrifugal force and in this manner the apparatus may easily be adapted for the treatment of difierent substances.

Figure 2 shows how the efiect can be still further increased by conducting the substances from the central disc on to several parallel discs, both sides of these discs being used. This apparatus has an axle A, to which is fixed a central disc B. To this there is fixed or integrally connected 8. ring R. Around this ring again there run two discs, C1 and C2, corresponding to disc C as shown in Fig. 1. When the substance is conducted through pipe D, it is flung out from disc B to ring R, which is provided with blades as above described, that convey the substance alternately up.

and down, to the upper or lower discs respectively. When the substance leaves the ring R, the distribution takes place in exactly the same manner as described above with reference to Fig. 1. In other words, the procedure is repeated.

In such an apparatus there is only one supply pipe, which itis very easy to regulate. If the apparatus is used for pulverizing concentrated salt solutions or melted salts or salts mixtures, the apparatus is as usual constructed with a h0llow axle and hollow discs, so that it can be heated by warm water, steam or electricity.

In Fig. 4 the shaft A is shown hollow and having a central tube a connected at its lower end with a channel 12 formed in the disc B and leading through a bridging connection d to the body C which is, in this instance formed with a closed hollow space 0. On the other side this space is through a channel e connected with the hollow space of the shaft A. The heating medium is introduced through the pipe a and passes through the channel I) to the space 0. and from th's through the channel e back to the shaft, from where it goes to a heater and so kept circulating through the apparatus. The particular means of heating the apparatus, howeverjforms no part of the invention.

I claim:

1. The process of treating liquid substance such as melts, solutions, emulsions or pulpy masses for the purpose of solidifying the same, which consists in first causing the liquid mass to be spread by the action of centrifugal force to form a continuous film, thereafter dividing the film into a number of rays, exposing said film rays to a successively decreasing resistance against its radial movement, while at the same time the material is continually extended by the action of centrifugal forceuntil the mass is flungofi and left to free fall, during which last period of the process the mass is solidified in the form of granules.

2. In a centrifugal apparatus, the combination with a central spreading disc and two annular resistance bodies the inner diameter of which is considerably greater than the outside diameter of the spreading disc, said annular resistance'bodies being disposed at an axial distance from each other on both sides of the central spreading disc, of an annular body having greater inner diameter than the spreading disc and smaller outer diameter than the inner diameter of the aforesaid annular bodies and being disposed in the space between said bodi'es so as to act as a distributor of the material from the central spreading disc to the said annular resistance bodies.

3. In a centrifugal apparatus, the combination with a central rotatable spreading disc, of an annular body surrounding the same and taking part in its rotation, said annular body having surfaces which slope axially and radially along the path of movement of the fluid over said body, the axial slope decreasing from the point at which the liquid strikes to the point at which it leaves said body.

NICOLAI STEPHANSEN.

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