US2573192A - Cyclone - Google Patents

Description

F. J.' FONTEIN Oct. 30, 1951 CYCLONE Filed Dec.

Patented Oct. 30', 1951 v CYCLONE Freerk Jan Fontein, Heerlen. Netherlands, as-

limor to De Directie van de Staatsmiinen in Limburg, Heerlen, Netherlands Application December 9, 1946. Serial No. 715,029

6 Claims.

Heretofore, cyclones have been principally used in the separation of solid particles from gases. or to concentrate or thicken suspensions of solid particles in liquids. In the copending application of Driessen et al., Serial No. 664,320, filed April 23, 1946, Patent No. 2,543,689, issued February 2'7, 1951, there is disclosed a process for separating solid particles of difierent grain size and diflerent specific gravity using a cyclone, the process involving the mixing of the particles to be separated with a liquid carrier and with relatively fine particles of a specific gravity higher than the specific gravity of separation. I have found that cyclones having the best separating effect in the separation of solid material from gases, and the best thickener efiect in the case of suspensions of solid particles in liquids, have the lowest separation efi'ect in the case of the separation of particles of difierent grain size and specific gravity in accordance with the Driessen et a1. process. This type of cyclone comprises essentially a shell in the form of an elongated frustum of a relatively steep cone.

The object of the present invention is to provide a cyclone with an improved form of vortex chamber which greatly raises the eificiency of the separating action in the case of particles of different grain size and specific gravity. To this end, the vortex chamber is made of generally conical form with the inner surface thereof in axial section defining an included angle which progressively increases toward the apex, providing a concave internal longitudinal contour. The progressively increasing angle may be defined by successive conical frusta of increasing flatness toward the apex, or the inner surface of the vortex chamber may be smoothly curved, as the sides of a bowl, adjacent the apex opening. Obviously the inner surface of the cyclone generally will define the outer envelope of the bod or mass rotating within the cyclone.

Illustrative embodiments of the invention are shown in the accompanying drawing wherein:

Figure 1 is an axial section of a cyclone whose shell comprises a series of conical frusta,

Figure 2 is a partial section like that of Figure 1 showing the attainment of concavity curvilinearly instead of by broken straight lines as in Figure 1, and More 3 is a view like that of Figure 2 showin a modification.

Referring to Figure 1, the cyclone shell is of generally conical form and comprises a cylindrical portion I surmounting a series of conical frusta 6, l and I. The cylindrical portion I is provided with a cover 8 having an axial discharge opening in. Reference numera1 ll designates a feed pipe disposed tangentially to section 6 and debouching into the interior thereof through an opening I2.

Section 6 is a frustum of a cone whose apex angle is 20. Section 1 has an angularity of and section 8 an angularity of and defines an apex opening l3 which is rimmed outwardly by a discharge nozzle H. The terminal section 8 may have an angularity anywhere from 60 to 90 or over. As for further characteristics, section 6 may have a diameter of 60 mm., base opening III a diameter of 18 mm., with inlet opening I 2 equivalent to 18 mm. in diameter. Section 6 may have a bottom diameter of 40 mm. and an altitude of 118 mm.; section 1 may have a bottom diameterof 25 mm. and an altitude of 19 mm.; and section 8 may have an apex opening 7 mm. in diameter and an altitude of 9 mm. These data are given as illustrative of a preferred form of cyclone under the invention.

In the practice, for example, of the aforementioned process of the Driessen et al. patent, it is desirable that any necessary addition of relatively fine particles be kept at a minimum. In this respect, comparison was made between a cyclone in accordance with the present invention, dimensioned as above, and a normal cyclone in which the vortex chamber was conical with an angularity throughout of 20, apex opening 7 mm. in diameter, base opening 18 mm. in diameter, inlet opening equivalent to 18 mm. in diameter, and maximum base diameter 60 mm.

The suspension was fed at the same velocity in both instances but less and less of the relatively fine particles was added so that the specific gravity of the suspension was progressively lowered.

In the case of the conventional cyclone, when the specific gravity was lowered to 1.07, all separating efiect disappeared. However, with the new cyclone and the specific gravity of the input at 1.07, there was still a very sharp specific gravity of separation at 1.42.

In the above tests the particles to be separated were intermixed coal and shale. With the specific gravity of the suspension greatly reduced by diminishing the amount of relatively fine particles added to the suspension, the conventional cyclone was inoperative whereas the new cyclone maintained an effective specific gravity of separation. Since the added relatively fine particles have to be recovered, it is obvious that the smaller the amount necessary to be added, the better, and consequently the new cyclone is of outstanding advantage in the practice of the said Driessen et a1. process.

In Figure 2 the cyclone is the same as that of Figure 1 except at its apex end which is longitudinally curvilinear. Section 1a between the imaginary lines a: and 11 corresponds in position and axial extent with section I of Figure 1 and section 8a with section 8. The angles, or mean angles, of section la and 8a correspond with those of sections 1 and 8, respectively. Operational results are the same, the diiIerence being that the conical frusta l and 8 are advantageous from a constructional viewpoint, being more readily formed than the curved section.

The apex end of the cyclone shell may be longitudinally convexed to the discharge opening with further improved results. In Figure 3, the body of the cyclone is like that of Figure 2 except that at the apex end, the concavity merges into an internally convexly curved funnel-like spout l5 which defines the discharge opening. In the illustrated form, any element of the shell has at its apex end a concavity which merges smoothly into a terminal convexity. This same form of spout could be provided with the shell of Figure 1.

Variations in form and proportions, beyond those disclosed, are contemplated under the claims which follow.

I claim:

1. The continuous process of separating into two fractions a liquid suspension having particles diverse both as to grain size and specific gravity whereby all particles of specific gravity less than a predetermined specific gravity of separation pass into one fraction while a second fraction contains particles of a specific gravity greater than the specific gravity of separation, which comprises establishing and maintaining a rotating body of such suspension in a confined generally conical space having axial discharge outlets at its ends from whence one fraction is continuously discharged from one such end while another fraction is continuously discharged from the other, continuously supplying such suspension tangentially to the rotating body in the region of the base of the conical space, and selectively controlling the specific gravity of separation by augmenting the suspension in the body with a solid material divided significantly finer than the smallest particles to be fractionated but having itself a specific gravity above the specific gravity of separation and in quantity suflicient to establish and maintain a barrier made up of mobilized solids disposed in the cyclone at its apex that is permeable by the particles of specific gravity greater than the specific gravity of separation but impermeable to the particles of specific gravity smaller than the specific gravity of separation, and maintaining the major portion of the length of the outer envelope of the rotating body within an included angle of the order of 20 and progressively increasing the included angle of the envelope from such included angle to the apex of the space to thereby minimize the quantity or augmenting material required.

2. A process of the character described in claim 1 wherein the outer envelope is a series of frustra.

3. A process of the character described in claim 1 wherein the portion of the outer envelope which has a progressively increasing included angle is curved lengthwise of the generally conical space.

4. A process of the character described in claim 1 wherein the portion of the outer envelope which has a progressively increasing included angle has a length which is approximately onefourth that of the major portion 01 the length.

5. A process of the character described in claim 1 wherein the initial increase of the included angle is of the order of 40.

6. A process of the character described in claim 1 wherein the included angle adjacent the apex is greater than 60.

FREERK JAN FONTEHN.

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

UNITED STATES PATENTS Number Name Date 446,053 Bittinger Feb. 10, 1891 709,956 Bailey Sept. 30. 1902 938,702 Porbeck Nov. 2, 1909 1,265,763 Fender May 14, 1918 1,832,256 Stebbins Nov. 17, 1931 2,377,524 Sampson et al June 5, 1945 2,471,326 Hoyt, Sr May 24, 1949 FOREIGN PATENTS Number Country Date 378,696 Italy Sept. 22, 1938

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