US3490947A - Anticrusting apparatus for continuous sugar centrifugal - Google Patents

Description

Jan. 20., 1970 w. GRIESELHUBER 3,490,947

ANTICRUSTING APPARATUS FOR CONTINUOUS SUGAR CENTRIFUGAL Filed July 10, 1967 v INVENTOR WILLIAM GRIESELHUBER United States Patent 3,490,947 ANTICRUSTING APPARATUS FOR CONTINUOUS SUGAR CENTRIFUGAL William Grieselhuber, Hamilton, Ohio, assignor to The Western States Machine Company, Hamilton, Ohio, a

corporation of Utah Filed July 10, 1967, Ser. No. 652,078 Int. Cl. C13f 1/02 U.S. Cl. 127-19 8 Claims ABSTRACT OF THE DISCLOSURE Sugar grains thrown from the rim of a continuously rotating upwardly open conical centrifugal basket are prevented from forming crusts and lumps in the surrounding casing by the action of a slowly rotating annular partition which presents a downwardly and outwardly sloping surface across the path of flight of the grains from the basket rim and coacts with blade means that bear constantly against said surface to remove any clinging material.

This invention relates to continuously operated sugar centrifugals making use of an upwardly open conical basket and, more particularly, to apparatus for preventing the formation of crusts and lumps of compacted sugar grains and fragments thereof which commonly develop within the curb, or casing, surrounding the basket in zones of impact of the sugar grains thrown radially from the rim of the basket.

In a typical continuous centrifugal machine as used in the manufacture of sugar a stream of a mixture of sugar crystals and syrup, such as sugar massecuite, is delivered continuously into a spinning basket having a conical perforate wall covered by a screen through which the liquid phase of the mixture is extracted by centrifugal force. The sugar crystals move along the screen toward a discharge rim at the upper end of the basket, from which they are thrown radially outwardly at very high velocity.

Owing to the force of the impact of the thrown sugar grains and the presence of moisture under normal op erating conditions, a crust or layer tends to form on the curb structure or casing surrounding the basket. The crust may build up to a thickness of as much as two inches, more or less, and often hangs on the curb structure until, ultimately, its weight causes it to break up into lumps or chunks of compacted sugar which drop into and become mingled with the purged sugar grains being collected in the sugar compartment of the curb around the basket. As a consequence, crusts or lumps of various sizes are mixed in with the desired loose sugar produced by the machine.

It is a primary object of the present invention to prevent chunks of compacted sugar from forming in the curb and mixing with the loose purged sugar delivered from continuous sugar centrifugals, and to avoid the losses and expense heretofore incident to the development of crusts and lumps within the curb structure.

It has been found that this object can be attained and the desired loose purged sugar produced continuously with little or no difficulty from the development of crusts and lumps of compacted sugar grains and fragments thereof within the curb of the centrifugal machine, by providing within the curb an annular partition that presents a downwardly sloping inner surface across the path of the flight of sugar grains thrown from the discharge rim at the open or upper end of the basket, which surface absorbs much of the kinetic energy of the flying grains and causes them to fall into the sugar-receiving compartment of the curb; arranging in continuous engagement with the inner surface of the partition suitable means, for example, scraping blades having free edges constantly bearing against that surface, for wiping any crystal fragments or other clinging material therefrom; and providing suitable means for slowly rotating the partition relative to the wiping means, or vice-versa if desired, so that any sugar solids clinging to the partition will be removed without building up into a crust.

According to another feature of the invention, the inner surface of the partition is formed of a material having a very low coefllcient of friction and little adhesivity to moist sugar crystals or fragments thereof, so that the partition will tend to shed the grains thrown against it from the basket and will be easily wiped clean of any clinging material. It has been found that these effects can be realized by providing a coating or layer of a material such as polytetrafluoroethylene, known commercially as Teflon, over the inner side of the partition.

According to a further feature of the invention, the wiping means coacting with the partition comprise one or more wiping or scraping units, preferably several of them spaced apart about the inner circumference of the partition, each of which comprises a series of several flexible blades which are arranged to act upon respective vertically adjacent areas of the inner surface of the partition, being held at an angle thereto with their outer edges pressed constantly against that surface, and means are provided for adjusting the angular position of the blades of each wiping or scraping unit so that a desired scraping or wiping pressure can be established at the blade edges and can be readily maintained by adjustments to compensate for blade wear. In an advantageous embodiment, each unit has several flexible blades mounted in end-to-end relation on an adjustable arm which is supported from the top of the curb so as to be accessible and turnable from a location outside the curb to adjust the position of the blades relative to the inner surface of the partition.

The foregoing and other objects, features and advantages of the invention will be apparent from the following detailed description of an illustrative embodiment thereof and from the accompanying drawing in which:

FIG. 1 is a fragmentary vertical sectional view of a continuous centrifugal machine provided with an apparatus according to the invention;

FIG. 2 is an enlarged view of the upper right-hand portion of the structure of FIG. 1;

FIG. 3 is a fragmentary plan view taken on line 33 of FIG. 2, showing a segment of the rotatable partition and the structure supporting it; and

FIG. 4 is a fragmentary cross-section taken on line 44 of FIG. 2, showing a disposition of the wiping means relative to the rotating partition.

The continuous centrifugal machine schematically illustrated in FIG. 1 is one of a known type often used for separating sugar crystals from molasses or syrup in sugar factories or refineries. The machine includes a centrifugal basket 10 rotatable at high speed about a vertical axis and having an upwardly opening perforate frusto-conical wall 11 covered in known manner by a fine filtering screen (not shown) over which the solids pass to a discharge rim 12 at the upper end of the conical wall. The purged sugar solids are thrown radially outwardly from the basket rim in a continuous scattering stream, by centrifugal force, to be collected in the sugar compartment 28 of a curb structure or casing 24 surrounding the basket assembly.

The basket 10 has a closed lower end structure 13 at the smaller end of the frusto-conical wall 11, which structure is fixed to an upstanding central hub 14 and contains an annular cup surrounding the hub. The cup receives a stream of the feed material, such as a sugar massecuite flowing continuously into the basket, and it accelerates the material and causes it to climb upwardly from the cup to pass over the filtering screen. The hub 14 is secured to a vertical shaft 16 rotatably mounted within a bearing housing 17 which is supported for gyratory movement by arms, one of which is indicated at 18. The arms are connected with a base or mounting structure (not shown) in a known manner. The shaft 16 is driven by a pulley and belt 19 from a motor located to one side of the machine.

The perforate wall portion 11 of the basket 10 is surrounded by a vertical partition 20 which forms a compartment 21 to receive syrup passing through the basket perforations. A floor 22 of this compartment leads the syrup to an outlet conduit 23 by which the syrup is carried away from the machine.

The sugar compartment 28 of the curb structure or casing 24 is formed between an outer cylindrical wall 25 .thereof and the partition 20 of the syrup compartment. The curb structure has a top wall 26 formed with a central opening 27 through which a stream of massecuite, or the like, is poured continuously into the cup 15 in the bottom of the basket. The lower end of the sugar compartment 28 is provided with suitable means, not shown, for delivering the purged sugar away from the machine.

In the usual operation of a centrifugal machine of the type described, the sugar crystals leaving the basket screen are flung at an extremely high velocity from the discharge rim of the spinning basket. They strike surfaces at the inside of the surrounding curb wall with such great force that many of them, especially in the processing of materials containing relatively large or relatively pure sugar crystals, tend to be fractured or broken into small fragments, sometimes referred to as smear, which will accumulate in a crust and will gather larger grains into the crust until the crust becomes so bulky and heavy that it may fall off the curb wall and break into lumps which mingle with the desired granular product in the sugar compartment.

This problem is overcome or greatly alleviated according to the present invention.

In the illustrated embodiment, a slowly rotating annular partition 30 is mounted inside the curb wall 25 at a. location across the path of the flight of sugar grains from the discharge rim 12 of the basket. This partition presents a downwardly sloping inner surface 31 which may be arranged at any desired angle, up to the vertical, to the generally radial path of such flight.

The partition 30 as shown is inclined both downwardly and outwardly at an angle to the flight path of the sugar grains so that its inner surface 31 not only will receive the impact of the flying grains with absorption of most of their kinetic energy but also will deflect the grains downwardly into the compartment 28. The partition shown is a frusto-conical sheet metal member of large diameter having its inner surface 31 made smooth and non-attractive to the material thrown against it from the basket. For this purpose, its inner side is advantageously coated with a thin layer 32 of polytetrafluoroethylene or other suitable composition having an extremely low surface attraction for particles of sugar or sugar solutions.

The frusto-conical partition 30 is fastened as by bolts 34 to several brackets 35 spaced apart about its outer side. The brackets are fastened to carrying rings 36 and 37 by bolts 38. These carrying rings have supporting lips 42 secured to them and projecting radially outwardly from them at intervals about their circumference. The lips 42 extend over and rest slidably upon the upper edge of an annular rail or bearing ring 39 which is fixed to a flange 40 at the upper end of the curb wall 25. The top wall 26 of the curb is bolted to the flange 40 and spaced above the rings 36, 37 and lips, 42 by a spacer ring 43 resting upon flange 40.

The annular partition 30 is rotatable slowly about its central axis, which substantially coincides with the axis of rotation of the basket 10, by a pinion 45 the teeth of which are in mesh with a roller chain 47 that encircles the lower part of the carrying ring 36 at its outer side and is attached thereto between flanges fixed to that ring.

The pinion 45 is pinned to a shaft 46 which is journaled in a fixed bearing 48 and driven by a motor or other suitable driving means at a speed giving the partition 30 a slow speed of rotation, for example, about 1.6 r.p.m., suflicient to keep its inner surface 31 wiped clean of any material adhering to it, by its continuous movement past the blades 52 of coacting scraping or wiping units 50 provided at several circumferentially spaced locations in the path of rotation of the partition. In the embodiment shown there are four of the units 50, but it will be understood that a smaller or larger number of them may be employed if desired.

Each scraping or wiping unit in the illustrated embodiment of the invention includes a series of four flexible blades 52, preferably made of an anti-corrosive sheet metal, which are arranged in endwise alignment on an arm 53 spaced inwardly from the inner surface 31 of the partition in substantially parallel relation thereto. The blades are fixed'to the outer side of the arm 53 and extend outwardly from it at an angle to the adjacent face of the partition so that their outer edges will press evenly against, and will scrape or wipe adhering material from, the inner surface of the partition.

The upper end of each arm 53 is fixed to a mounting pin 54 rotatably supported in a split clamping block 55 mounted on the top wall 26 of the curb. A set screw 56 threaded in the block and a clamping bolt 58 for the split block enable the angular position of the pin 54 and arm.

53 to be adjusted and reset as and when required.

By simple manipulation of a head 59 of the pin 54, which is accessible from outside the curb, the arm and blade position can be adjusted so as to keep the blades flexed and pressed against the partition at an angle assuring that their edges will always function to keep the rotating partition clean.

While the principles of the invention and a preferred way of putting them into practice have been described hereinabove, it will be evident that the invention is not restricted to particulars of the illustrated embodiment and that it can be practiced in other ways within the scope of the appended claims. For example, instead of the illustrated blades having edges pressed against the partition, other forms of scraping or wiping devices, such as suitable wires or brushes held against the face of the partition, may be employed; and instead of providing means for rotating the partition, the partition may beheld stationary and the wiping or scraping means mounted on a suitable slowly rotated ring structure.

What is claimed is:

1. In a centrifugal apparatus for continuously separating sugar crystals from syrup, including a perforate conical centrifugal basket rotated continuously about a vertical axis within a surrounding casing to drain syrup through the basket perforations and throw sugar grains radially from a discharge rim at the larger end of the basket, means to prevent sugar grains thrown from said rim from forming crusts and lumps within the casing, comprising an annular partition within said casing presenting a downwardly sloping inner surface across the path of the flight of said grains from said rim to absorb kinetic energy of said grains and cause them to fall downwardly in said casing, means bearing continuously against said inner surface for wiping any clinging material therefrom, and means for maintaining said partition and said wiping means in relative wiping motion circumferentially of said casing.

2. Apparatus according to claim 1, including means mounting said partition for rotation about a. vertical axis substantially concentric with said basket axis and drive means for slowly rotating said partition thereabout.

3. Apparatus according to claim 1, said partition being a ring' of rigid sheet material having a downwardly and outwardly sloping inner surface lying across said path.

4. Apparatus according to claim 1, said inner surface being formed by a layer of polytetrafluoroethylene over the inner side of said partition.

5. Apparatus according to claim 1, said wiping means comprising blades having scraping edges pressed constantly against said inner surface.

6. Apparatus according to claim 1, said wiping means comprising flexible blades bearing against said partition at an angle thereto with the outer edges pressed constantly against said inner surface, and means for adjusting the angular position of said blades relative to said surface.

7. Apparatus according to claim 1, said wiping means comprising a plurality of wiping units spaced apart about the inner circumference of said partition, each of said units comprising at least one blade having a scraping edge pressed constantly against said inner surface.

8. Apparatus according to claim 7, each of said wiping units comprising a support arm inwardly from and extending substantially parallel to said inner surface, a plurality of flexible blades mounted in end-to-end relation on said arm, each of said blades extending to said inner surface of said partition at an angle thereto and constantly pressing against said inner surface along an edge of the blade, and means mounting said arm on the top of said casing, said mounting means being accessible and turnable from outside said casing for adjusting the angular 5 position of said blades relative to said inner surface.

References Cited UNITED STATES PATENTS 10 1,839,941 1/1932 Zelezniak 210-369 X 1,933,644 11/1933 Trump 210369X 2,889,930 1/1959 Tholl 210-4369 3,290,172 12/1966 Dietzel 12756X 15 3,238,063 3/1966 Steele 127-56 X 3,301,708 1/1967 Rotel 127-19 FOREIGN PATENTS 1,375,219 9/1964 France.

MORRIS o. WOLK, Primary Examiner S. MARANTZ, Assistant Examiner US. Cl. X.R. 210-369

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