US2296945A - Centrifugal curb liquid separation - Google Patents

Description

A. OLCOTT 2,296,945

CENTRIFUGAL CURB LIQUID SEPARATION I Sept. 29, 1942.

Filed Aug. 3, 1940 FIG.

FIG. 3

INVENTOR C. A. OLCOTT ATTORNEY Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE 2,296,945 CENTRIFUGAL CURB LIQUID SEPARATION Charles A. Olcott, West Milford, N. J. Application August 3, 1940, Serial No. 350,439

7 Claims. (01. 210-75) This invention relates to centrifugal apparatus and more particularly to centrifugal separators of the kind employed in the refining of sugar.

In any process of refining sugar a stage is reached where precipitated sugar crystals dispersed throughout a mass of the molasses-like mother liquor are separated 'fromor purged of the adhering fluid by centrifugal action; The centrifuge usually employed for this operation comprises a rotatable basket with perforated side walls through which the adhering fluid is in large measure expelled or spun off as green syrup. Inasmuch as the initial purging is not quite effective to free the crystals of all of the adhering molasses it is the practice to remove the residue by washing the sugar with hot water or steam while still in the centrifuge and to remove the resulting wash syrup by further centrifuging.

The green syrup that is first removed and the wash syrup that immediately follows it both contain a substantial percentage of dissolved sugar but in view of the disparity between the purities of the two syrups quite different processes are required for the subsequent efficient recovery of their respective sugar values. 'For this reason it is imperative that the two syrups be separately collected and that mixing of the two even within the centrifuge be minimized.

Heretofore centrifuges have been provided with 7 separate interior collecting troughs or gutters for the several types of fluid expelled andan interior classifier that may be moved from one position to another to guide the centrifuged fluids that successively flow down the interior wall or curb of the centrifuge casing to their respective collecting troughs. In theory such interior classifiers are capable of effecting sharp separation of the various classes of syrup but in practice it is found that they suffer from serious defects that greatly impair their general utility. A major difiiculty arises from the viscous and adhesive qualities of the fluids encountered in the sugar refining art. These tend to make the operation of the classifier stiff and sluggish at best with consequent inaccuracy in timing the operation of the classifier to coincide precisely with the transition from one type of curb syrup to another. Adhering syrup that is allowed to dry and'harden forms an especially tenacious bond, and too often it happens that the classifier is permanently deformed or broken by too forceful efforts to free and operate it. Efficient separation of syrups depends on a tight joint between the classifier and the part against which it bears, hence the importance of avoiding any permanent deformation of the classifier. Moreover, such impairment of the joint would not be visible from outside the centrifuge and the resulting leak might continuously mix syrups that should be separated. It should be apparent that costly and time-consuming repairs or inefficient operation may readily be entailed.

A principal object of the present invention is to provide an improved centrifuge of the kind described and more particularly to effect improved curb liquid classification. A subsidiary object is to provide a curb syrup classifier that is rugged in construction and that is readily operated in the presence of viscous syrups and hardened adhesives to effect accurate and certain separation of curb syrups and the like.

Various" other objects, features and advantages of the present invention will appear to those skilled in the art from a consideration 'of the preferred embodiment illustrated in the accompanying drawing and now to be described. In the drawing, Fig. 1 shows in partial crosssection a centrifuge incorporating a curb syrup classifier in accordance with the invention, and Figs. 2 and 3 show details thereof.

Referring more particularly now to Fig. 1 there is represented a centrifuge comprising the usual basket I with perforate side Wall suspended at the lower end of a vertical drive shaft 2 within a suitable housing or casing. In the centrifuging operation, the molasses, wash water and the like fluids successively introduced into the basket are cast off through the lateral perforations while the crystalline sugar builds up on the interior face of the basket. The centrifuged fluids strike the interior casing wall or curb 3 and flow down its face for collection in and discharge from one or another of a plurality of concentric annular troughs or gutters.

Two troughs, 4 and 5, are shown and these are separated and partially bounded by a vertical annular wall or partition 6. At its upper extremity partition 6 curves radially outward to provide a horizontal annular ledge or flange I. The gap 8 between the outer edge of flange 1 and curb 3 affords a passageway for curb syrups destined for outer trough 5. The gap itself is not a complete annulus for it is closed by flange 1 over an arouate section 9 underlying the classifier operating mechanism shown at the left.

overlying the gap 8 and extending circumfer entially to overlap the ends thereof is the classifier element 10. In cross-section the latter may be, and preferably is, approximately. L-shaped, as

classifier preferably contacts the curb 3 thereby avoiding the formation of a syrup collecting pocket between separator and curb.

In what I conceive to be its optimum form the classifier [0 comprises an integral r'net'allicv piece, .i' preferably of steel, adapted for flexure .to.the,.

several operating diameters without exceeding the elastic limit of the material comprising it.

The integral classifier may be so proportioned that when unrestricted it assumes a diameter somewhat greater than that of the curb 3, so that when in place within the centrifuge it tends to force itself against the curb and thereby to provide a tight seal. It may also be proportioned in accordance with known principles, as by providing a greater thickness of material in aportion opposite the gap between its ends, so that it will tend to retain an arcuate shape of substantially uniform radius in each of its operating positions. 7

The preferred method of operatingthe classifier l0 and details of a preferred mechanism for this purpose in accordance with the invention will be described with reference to Figs. 2 and 3, which show respectively horizontal and vertical cross-sections of the operating mechanism depicted more generally in Fig. 1. In thisembodiment there is fixed to each end of the integral classifier I!) a clevis 2! which is loosely pinned to a respective operating lever 22, 23, that extends through a short circumferential slot 24 in the casing. Covering the slot 24 is a housing 25 which prevents the escape of centrifuged syrups. Extending through casing 25 are vertical shafts 26 and 21 which comprise driving pivots for the operating levers 22 and 23, respectively. These shaftscarry a pair of inter-meshing pinions immediately above housing 25, and a lever handle 29 is attached to shaft 21 for manual operation. Anysuitable means, such as a notched segment, may be used for holding the handle 29 in each of its operating positions. Suitable additional equipment may be provided for automatic timed operation if desired. 7

With the classifier H1 in its fully expanded position as illustrated in Fig. 2, operation of the handle 29 clockwise urges the clevises 2| and the ends of the classifier together thereby contracting the classifier to the smaller of its operating diameters. It is important to note that although the force applied to the classifier is applied at only two points thereof, viz., its ends, the forces required to break it loose when it is sealed in position by hardened syrups are communicated by tension to all sections of the classifier, and that the classifier is well adapted by its form to sustain tensile forces without being deformed or broken. It may be noted too that almost none of the classifier operating mechanism lies within the curb or in a position to be washed by curb syrups that might dry and harden on them and contribute to difficulty of operation.

In accordance with an important feature of the invention the shifting of the classifier to a new position takes place progressively around the classifier, or in other words the classifier is stripped free from the curb or from whatever other fixed part of the centrifuge it may adhere to. This progressive rupture of the bond between the classifier and the curb, for example, obviously requires but a small fraction of the force that would be required if the bond were to be broken at all points simultaneously as done heretofore.

The feature last described is incorporated in the embodiment illustrated in the drawing and -may be readily understood on further consideration of Fig.. 2. With the classifier in its fully expanded position as illustrated the operating levers 22 and 23 diverge, hence the clevises 2| and the attached ends of the classifier are urged inward and away from the curb when the handle'29 is moved. An initial effect then is to break the ends of the classifier l 0 away from the curb and from adherence thereto. On further movement of' the handle the point of contact with the curb moves circumferentially around the curb and successive sections of the classifier are pulled free. It is much to be preferred if the classifier is loosed first at one end and subsequently at the other. All that is necessary to bring about this result in the embodiment disclosed is to provide for a substantial amount of lash in the fit of pinions 28 so that lever 23 is moved enough to free the end of the classifier to which it is attached before lever 22 begins to move.

Although the present invention has been described in terms of a preferred illustrative embodiment I realize that the invention and its several features are susceptible of embodiment in a wide variety of other forms, hence the invention is to be understood as comprehending such other forms as may fairly come within the spirit and letter of the appended claims.

I claim? 1. A centrifugal machine comprising a rotatable basket, a casing enclosing said basket and comprising a curb, inner and outer concentric channels within said casing and below said curb having respective top openings for receiving curb fluids; a flange at the top of said outer channel restricting the width of itssaid top opening, an integral metallic classifier mounted on said flange, said classifier being elastically adjustable to alternative operating radii the larger of which is such that said classifier closes the said top opening of said outer channel and the smaller of which is such that said classifier exposes said opening, and an actuator controlling the operating radius of said classifier.

2. A centrifugal machine comprising a rotatable basket, a casing enclosing said basket and comprising'a curb, inner and outer concentric channels within said casing and below said curb having respective top openings for receiving curb fluids, an integral metallic classifier mounted above said channels, said classifier being elastically adjustable to alternative operating radii the larger of which is such that said classifier closes the said top opening of said outer channel and the smaller of which is such that said classifier exposes said opening, and an actuator controlling the operating radius of'said classifier.

3. A centrifugal machine in accordance with claim 2 in which said actuator comprises means for urging one end of said classifier toward the other end thereof and inwardly from said casing, whereby said classifier is effectively stripped from its position when operated to the smaller of said diameters.

4. A centrifugal machine in accordance with claim 2 comprising a pair of operating levers pivoted externally of said curb and extending inwardly with divergence, the inner ends of said levers being connected respectively with the ends of said classifier, and an actuator for controlling the divergence of said levers.

5. In a centrifugal machine, a centrifugal basket with perforate wall, a surrounding casing comprising a curb for directing downwardly liquids centrifuged from said basket, inner and outer annular troughs below said basket for receiving curb liquids, said troughs being separated by a common annular partition, an annular external flange at the top of said partition restricting the opening into said outer trough, an integral, elongated and substantially arcuate member adapted to rest on said flange, said arcuate member being flexibly adjustable to a first diameter such that it closes said opening and to a second diameter such that said opening is exposed, and outwardly extending members operatively connected to the ends of said arcuate member for changing the diameter to which it is flexed.

6. A centrifugal machine for the purging of sugar or the like comprising a rotatable, laterally perforate basket for containing the material to be centrifuged, a single curb surrounding said basket in a position to receive the fluids centrifugally expelled from said basket, a pair of concentric annular collecting troughs below said curb, a fluid classifier over said troughs adapted to direct expelled fluids that flow down said curb selectively to said respective troughs according to its operating position, said classifier comprising an integral elastically-deformable strip positioned over said troughs and disposed in one of its operating positions as a seal across the top of the outer of said troughs whereby fluids from said curb flow over said strip to theinner of said troughs, and an actuator for displacing said classifier strip from said one operating position, said actuator comprising means initially impelling at least one end of said strip inward.

'7. A combination in accordance with claim 6 in which said actuator comprises means for forcing the ends of said strip together whereby said strip is elastically adjusted to a reduced radius of curvature.

CHARLES A. OLCOTT.

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