US3496016A - Centrifuge - Google Patents

Description

Feb. 17, 1970 'wgb SIEPE T AL 3,496,016

CENTRIFUGE 4 Sheets-Sheet 1 Filed Sept. 8, 1 965 INVENTORS a a..-4/ESchmicZt w vgs A Feb. 17, 1970 w. L. SIEPE ETAL YCENT'RIEUGE 4 Sheets-Sheet 2 Filed Sept. 8, 19.65

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CENTRIFUGE Filed Sept. a; 1965 I 4 Sheets-Sheet 4 Fig. 5 y

I lull v I! i f 1 4 25 f 23 i v v I v i 1m lap vn 22 20 l h u INVENTOR5 I Mt. Sz'e ae w/vifischma'clt 3,496,016 CENTRIFUGE Werner L. Siepe, Heuchling, and Heinrich F. Schmidt,

Dusseldorf, Germany, assignors to Hein, Lehmann &

Co., A.G., Dusseldorf, Germany, a corporation of Germany Filed Sept. 8, 1965, Ser. No. 485,731 Int. Cl. 1504b 3/00 US. Cl. 127-19 4 Claims ABSTRACT OF THE DISCLOSURE A centrifuge has a frusto-conical sieve drum containing a hollow frusto-conical body, the portion of the body having the largest diameter being connected by a plate with the portion of the drum having the smallest diameter. A shaft section is connected with the plate while another aligned shaft section is connected with the portion of the body having the smallest diameter. The first shaft section is supported by a bearing below the portion of the drum having the smallest diameter and the second shaft section is supported by a bearing substantially at the level of the portion of the drum having the largest diameter.

This invention relates to a centrifuge and refers more particularly to a centrifuge having a sieve drum which extends conically outwardly toward the outlet.

The technology of centrifuging, particularly that of centrifuging viscous masses, following the. general tendency of modern engineering practice has set itself the goal of being able to use large amounts of .the mass being treated within the smallest possible space, since if the output is small, the necessary large number of treating devices presents problems pertaining to distribution, mixing and servicing which the constructor and user of such devices would gladly eliminate.

Obviously, these developments require that these devices must be operated continuously, since theautomatic but discontinuous manner of operation, while being satisfactory from the point of view of production, makes such demands concerning structure, servicing and functioning, that it is not advantageous any more in relation to the other costs. Furthermore, to adapt centrifuging to prevailing spacev conditions, the height of treating machines, particularly the height of centrifuges, should be kept as small as possible.

This is particularly applicable to the centrifuging of viscous masses, which must be treated with high centrifugal accelerations, as is the case, for example, in the sugar industry. There special limits are set for the sizes of centrifuges, since tensions to which the material is subjected in the centrifugal drum increase with an increase in diameter quicker than the desired centrifugal forces acting upon the material being centrifuged.

Centrifugal drums, particularly of the type using sieve drums which widen conically toward the outlet, are particularly easily subjected to becoming unbalanced; this can increase to a dangerous extent, so that often the centrifuge gets broken, endangering workers located in close proximity. The greater the centrifugal drum, the greater is the danger of unbalance.

Centrifuge engineering has tried to follow the wishes of the users of these centrifuges by attempting to increase the forces .acting upon the masses being centrifuged through special oscillation and acceleration ratios. Following this development centrifuges were produced which are provided with a sieve box which is also conical in the outlet direction, whereby the mass being sieved was placed upon the bottom of the centrifugal drum. In addition, the rotational movement was overlapped many Unit ed States Patent O times by axial oscillation procedures. Centrifuges of this type are usually supported on one side, whereby one bearing location is arranged directly below or in the bottom of the sieve drum; the other bearing, which is also necessary, is located below the first one at a distance determined by constructional considerations. This one-sidedly located arrangement of the supporting bearings of the centrifuge drum is of doubtful eificacy, since the center of gravity of the drum is located at an undesirably great distance from the support, particularly in case of centrifugal drums with wide surfaces. Since the output of a centrifuge is influenced to a considerable extent by the effective operational surface, this construction has its limitations, particularly since an intended increase in output through an increase in the surface necessitating an axial extension of the drum detrimentally increases the distance of the center of gravity; furthermore if the diameter is increased the extent of unbalancing which is unavoidable in operation, becomes stronger and more pronounced as the result of a larger radius.

Furthermore, the distribution of the filling mass is of particular importance in centrifuges. The described constructions solve this problem either by means of a socalled acceleration pot or by a supply directly upon the flat bottom of the centrifugal drum. In the latter case guide plates upon the flat bottom are often necessary to provide a better distribution of the centrifuged mass; however, these plates contribute to the destruction of the cores. It is also known to charge centrifuges of this con struction through a pipe which, while located within the centrifugal drum, does not rotate along with it. Constructions of this type generally use a comparatively short pipe, which also serves as a spray protector, the pipe being usually arranged close to the impact location of the mass at the bottom of the centrifugal drum.

An object of the present invention is to improve prior art constructions.

Another object is to provide a centrifuge the output of which will greatly exceed the output ranges of existing centrifuges.

Other objects of the present invention will become apparent in the course of the following specification.

In the accomplishment of the objectives of the present invention it was found desirable, as a condition for the treatment of extremely large filling masses, to support the centrifugal drum which extends'outwardly toward the outlet, on two sides within the cenrifuge casing and in such manner that one support, as is known, is located below the centrifuging drum, while the second support is located approximately at the level or above the upper edge of the drum, preferably in the cover of the centrifuge. The centrifuge is fed through the upper support location in such manner, that the mass to be centrifuged strikes a dividing cone which is located within an inner conical body adjacent an upper portion of a hollow shaft and which directs the mass to the inner walls of the conical body. Outlet slits are provided at the largest circumference of the conical body which is rotatable along with the sieve drum. The mass being centrifuged reaches through these slits the smallest circumference of the sieve drum while sliding over a centrifuging plate.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing, by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGURE 1 is a vertical section through a centrifuge of the present invention along with its belt drive.

FIGURE 1a is a section through a portion of the cover of the centrifuge showing centering by means of set pins.

FIGURE 1b is a sectionthrough a portion of another cover showing centering at the inner diameter of the casing by means of a worked centering seat.

FIGURE 2 is a side view, partly in section, of the lower portion of a somewhat differently constructed centrifuge and illustrates the centrifuging drive by means of conical wheels.

FIGURE 3 is a section along the line IIIIII of FIG. 1.

FIGURE 4c is a detailed view, partly in section, showing a portion of the cone surface with flap regulation of the outer slits by counter weights.

FIGURE 4b is a detailed view, partly in section, showing a portion of the cone surface with flap regulation by rotary coiled springs.

FIGURE 40 is a detailed view, partly in section, showing a portion of cone surface with flap regulation by a compression spring.

FIGURE 4d is a detailed sectional view showing the covering of the outlet slot by a resiliently elastic element.

FIGURE 5a is a top view of the device shown in FIG. 4a.

FIGURE 5b is a diagrammatic inner view of the cone with an outlet slit.

FIGURE 50 is a section along the line VcVc of FIG. 5b.

FIGURE 5d is a section along the line VdVd of FIG. 5b.

FIGURE 6 is a vertical section, partly a side view, of another embodiment having a hollow shaft with a ring transformer under the bottom of the drum.

A vertical longitudinal section through a centrifuge of the present invention is shown in FIG. 1. The centrifuging drum has the shape of a frusto-conical sieve drum 1 which is enlarged outwardly toward the outlet in a manner known per se; a flat charging plate 2 is located at the smallest diameter of the drum, and is connected therewith. An inner frusto-conical body 3 is fixed to the plate 2 and is provided with outlet slits 3a. The inner surface of the conical body 3 has the task to direct the mass to be centrifuged in the form of a thin layer and with uniform acceleration to the smallest diameter side of the drum 1. A distributing cone 4 is located for this purpose centrally close to the smallest diameter of the conical body 3; the cone 4 guides the mass to be centrifuged which arrives from a charging nozzle 5, directly to the inner surface of the conical body 3. From there the mass passes through slits 3a and over the fiat plate 2 to the smallest diameter side of the sieve drum 1.

The conical body 3, the plate 2 and the drum 1 are firmly connected with each other and constitute the centrifugal drive. In the embodiment shown in FIGS. 1 and 3 they are driven by a belt drive actuating a solid shaft section 30 located at the lower part of the apparatus and firmly connected with the plate 2.

In order to attain the object of the present invention, namely, to be able to process extremely large masses, the centrifugal drum 1 requires a large sieve surface. The comparatively large sieve drum 1 constructed for this purpose is supported on two sides, so as to be able to absorb the resulting large bearing forces. One support is constituted by a lower bearing 6 below the bottom of the centrifuging drum 1. The bearing 6 supports the shaft end 30. The second support is constituted by an upper bearing 7 mounted in the cover 8 of the casing 9 above the drum 1. The bearing 7 supports a tubular member 3b which is integral with and constitutes a continuation of the conical body 3. The member 3b constitutes a second shaft section aligned with the shaft 3c. This construction makes it necessary to center the cover 8 relatively to the casing 9 of the centrifuge. This can be attained by means of centering pins 10 shown in FIG. 1a.

Instead of using the pins 10 the cover may be shaped as a worked centering seat, as illustrated in FIG. 1b.

A somewhat different drive is shown in FIG. 2 which illustrates the use of two motors connected with cone gears which drive the main shaft 12.

In actual operation it is not possible to avoid that larger pieces in the form of baked together sugar masses or foreign substances will reach the centrifuge as a part of the mass being centrifuged. Very large pieces can be held back by a sieve located in front of the charging device. In order to prevent the clogging of the machine by the remaining larger pieces, it is necessary to provide adequately wide cross-sections between the distributing cone 4 and the conical body 3 on the one hand and the lower outlet slits 3a of the conical body 3 on the other hand. If the outlet cross-sections have the size which is indicated diagrammatically in FIG. 1, then the mass being centrifuged which flows as a thin layer outwardly over the conical body 3, will emerge directly at the upper edges of the slits 3a; it will then fly freely through space and will reach the sieve drum 1. However, the cores of the mass will be destroyed as the result of this impact.

This drawback is avoided in accordance with the constructions shown in FIGS. 4a to 4d by covering the outlet slits 3a by movable fiaps which leave open only a narrow space close to the bottom of the distributing plate 2 for the passage of the normal centrifuging mass. The flaps have the tendency to open and to be held in a certain position under the action of centrifugal forces. It is generally necessary that a somewhat larger counter force be exerted upon them.

For that purpose, according to the construction shown in FIG. 4a a lever 13 with a counter weight is provided. FIG. 5a is a top view of the same construction.

FIG. 4b shows a rotary coiled spring 14 used for the same purpose.

FIG. 4c shows a compression spring 15 used for the same purpose.

FIG. 4d shows that the same purpose can be attained by making the flap 16 elastic as well as resilient.

If conditions become worse than normal or if large pieces cover the slits, it will be necessary to upset the mass being centrifuged; then its centrifugal force will be sufficient to hold open the flaps for a while.

There is also another possible way to guide the mass through the comparatively narrow slits directly to the distributing plate 2 of the centrifuging drum or box 1, which consists in the provision of guiding ribs 17 shown in FIGS. 5b and 5c. The ribs 17 guide the charging mass under normal conditions directly to the narrow slits. The slits are somewhat increased in the flow range provided by the ribs 17 to facilitate the passage of possible larger pieces. Such large pieces can roll over the guide ribs and pass through an enlarged portion 3d of a slit 3a upon the bottom of the distributing plate. Furthermore, wedge-shaped guiding pieces 18 can be provided between the slits so as to avoid dead spaces between them. FIG. 5b is a partial sectional inner view of such an outlet slit. FIG. 50 is another vertical section, while FIG. 5d is a horizontal section. A further advantage of the wedge-shaped guiding pieces is that they counter balance the weakening of the rotary parts caused by the outlet slits.

It is a matter of general knowledge that the viscosity of the filling mass may change greatly within a comparatively small temperature range. A low viscosity is desired since this improves the centrifuging process. Therefore, a preliminary heating even to the extent of only a few degrees can be advantageous to facilitate a uniform supply of particularly tough viscous filling masses to the sieve drum. The heating of the mass shortly prior to the centrifuging is also particularly important since only thus it is possible to provide more time for the sugar crystals to become dissolved as a result of an increase in temperature. For that purpose the conical body 3 is provided with means which can be embedded or applied to its surfaces and which heat the mass being centrifuged during its passage, whereby the inner side of the supply funnel is used for heat transfer. The contacting inner surfaces may be increased through the provision of grooves or ribs.

One of the possible constructional embodiments is illustrated in FIG. 1 which shows a concentrical induction coil 19 extending around the conical body 3. This coil does not rotate but is fixed to the casing by any suitable means (not shown). The coil 19 heats the body 3 by induction and radiation heating.

A further possibility of providing a supply of heat is that of resistance heating of a jacket. A transformer rotating with the centrifuging parts is advantageously used to supply energy for this purpose. This arrangement is illustrated in FIG. 6 which shows three contact rings 21 supplying primary electrical current to a ring transformer 20. The secondary winding of the transformer consists of several uniformly distributed loop-shaped conduits 22 consisting preferably of fiat copper. The inner legs of these conduits are connected with a copper shaft 23 by bolts which extend through the distributing plate 21 but are insulated from the plate and which are fixed to the contacting flange of the shaft 23 in an electrically well conducting manner. The copper shaft 23 may be solid or hollow. It extends along the central axis of the apparatus and is connected at its upper end with a conical body 3 by several radially extending flat copper plates or struts 24.

In this construction the distributing cone 4 used for the distribution of the centrally supplied mass to be centrifuged is fixed upon the radial copper plates. The outer legs of the conduits of secondary current are firmly screwed upon the distributing plate 2 This arrangement provides a simple secondary circuit which is constituted by secondary conduits 22, the copper shaft 23, the radial struts 24, the conical body 3 and the distributing plate 2 It is easily possible to adjust the resistances of the individual parts of the secondary circuit in such manner that their value is essentially determined by the resistance of the conical body 3 so that the desired heat effect is attained there. This can be achieved, firstly, by the selection of suitable cross-sections for the current-conducting parts and, secondly, by the use of chrome-nickel steel for the conical body, the electrical conductivity of which is about 40 times less than that of copper.

Obviously it is also possible to provide the heating directly or indirectly by steam or by radiation.

Practical experience has shown that a centrifuge of the present invention can attain an output which heretofore was possible only by joining several centrifuges.

It is apparent that above-described examples have been given solely by way of illustration and are capable of further variations and modifications within the scope of the appended claims.

What is claimed is:

1. A centrifuge, comprising a frusto-conical sieve drum, a hollow frusto-conical body within said drum, a plate connecting the portion of said drum having the smallest diameter with the portion of said body having the largest diameter, a dividing cone within said body adjacent the portion thereof having the smallest diameter, means supplying a mass to be centrifuged to said dividing cone, said body having slits adjacent said plate, whereby said mass reaches the portion of the drum having the smallest diameter through said slits and over said plate, driving means for said drum, said body and said plate, and separate bearings for said driving means below the portion of said drum having the smallest diameter and substantially at the level of the portion of said drum having the largest diameter.

2. A centrifuge according to claim 1, comprising flaps partly covering said slits and swingably connected with said body and means connected with said flaps for adjusting the effective sizes of said slits depending on the centrifugal forces exerted on said flaps, said swingable flaps permitting the passage of abnormally large pieces of the mass being centrifuged.

3. A centrifuge according to claim 2, comprising guiding ribs carried by inner surfaces of said body and extending toward said slits, each of said slits having a wider portion and a narrower portion circumferentially spaced from said narrow portion.

4. A centrifuge according to claim 3, comprising wedgeshaped guiding pieces located within said body between said slits.

References Cited UNITED STATES PATENTS 59,956 11/1866 Brown 210369 124,197 3/1872 Donner et al 12764 X 1,954,676 4/1934 Lindberg 210369 X 2,100,118 11/1937 Andrews 127--19 X 2,643,960 6/1953 Hoyt 127-19 X 3,205,095 9/1965 Dietzel et al. 12719 574,439 1/1894 Mays 23311 1,196,829 9/1916 Wescott 23311 1,482,229 1/1924 Hapgood 233 11 1,525,808 2/1925 Hall 23311 2,973,288 2/1961 Riedel 12756 X 3,129,174 4/1964 Pickels et a1. 233-11 MORRIS O. WOLK, Primary Examiner D. G. CONLIN, Assistant Examiner US. Cl. X.R.

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