US1592717A - Centrifugal basket - Google Patents

Description

Patented July 13, 1926.

UNITED STATES l 1,592,717 PATENT orrlcs.

FLOYD IP. BRENEMAN, OF HABANA, CUBA.

GENTRIFUGAL BASKET.

Application filed July 7,

The present invention relates to improvements in centrifugal baskets and more specifically to an improved basket for use more particularly in connection with low grade sugars. s

In the centrifugalling of the fluid mass, the material has a climbing tendency, that is the material in the basket, due to the high velocity of rotation of the basket, tends not only to move out radially against the wall ofthe basket, but also to rise upwards along the cylindrical wall of the basket. In other words the material has a tendency to creep from the bottom upwards. If the walls of the centrifugal were of infinite height, the mass would spread out on the walls in thickness varying from bottom upwards and getting progressively thinner toward the top. A cross section vertically would resemble a parabola.

In the conventionally used centrifugal, however, there being a limit to the depth of the basket, this climbing tendency is limited by the top curb, so that a cross section shows practically the same thickness at the top as at the bottom.

In the purging of low grade sugar, one frequently finds on stopping the centrifugal when the operation is apparently nished that on the inner surface of the charge is a film or coat of molasses, this coat varying in thickness. In some cases the coat of molasses attains a great thickness and quite a quantity of molasses is left within the sugar. Also when this is observed, it is frequently found that the sugar behind is completely dried, .and free of molasses. When the centrifugal is stopped and the sugar discharged, naturally this molasses is discharged with it and again becomes mixed with the sugar to the commercial detriment of the same.

The cause of the formation of this film is considered to be the high initial speed ofthe r machines, and efforts are made in purging 1924. Serial N'o. 724,668.

the shape of the basket. By making the upper diameter of the basket smaller than the lower portion, it is aimed to make the cross section of the mass thinner at the top than at the bottom, and, should molasses separate and come to the inside, it can rise and go through the thin section at the top.

The invention is equally applicable to all types of centrifugal basket and the construction is such as to admit of only a slight variation over commercial baskets as used at the present time in order that the change may be achieved readily and without requiring any alteration in present machinery or methods.

lilith the foregoing and other objects in View, the invention will be more fully described hereinafter, and will be more particularly pointed out in the claim appended hereto. i

In the drawings, wherein like symbols refer to like or corresponding parts throughout the several views Figure l is a vertical section through a centrifugal constructed according to the present invention, and

Figure 2 is a vertical section of a conical basket employing the invention.

Referring more particularly to the drawings l designates the usual casing adapted to collect the molasses which is thrown out by the centrifugal action through the perforated centrifugal wall 2 of the basket which rotates with the power shaft 8. In the in stance shown the sugar is allowed to descend through the central opening 4 of the casing when the centrifugal is stopped, this sugar being guided toward the center bythe inverted frusto-conical head 5 at the lower end of the basket.

The material is poured in through the opening in the top'of the casing in the usual manner and is deflected as by the cone 6 against the side of the centrifugal. Inas much as this is undergoing rapid movement. the act of separation immediately begins and the greater quantity of the molasses is thrown through the perforated wall of the centrifugal basket, while ythe mass of sugar is held within this wall and gradually increases in thickness as the action goes on.

Usually a backing screen 7 is provided upon the interior of the cylindrical wall 2 and within the backing screen is a perforated metal screen 8. This interior perforated screen 8 has usually from 400 to 625 holes per square inch, in accordance with the character of the sugar or other material to be treated. The baslet is usually provided at its top with an inwardly projecting curb lying at almost right angles to the axis of the basket and forming asubstantial abutment against which the upper end of the sugar column may strike to Yresist the climbing tendency of the charge as above referred to. The result is that the* sugar piles up in a substantially uniforn'i mass or zone along the cylindrical wall of the basket and the suf packs in very tightly, particularly after the action has been allowed to go on for some time and there is a substantial resistance to the movement of the molasses through this packed sugar.

A film of molasses separates out upon the interior of the sugar column and is troublesome7 if not entirely impracticable, to get rid of by present constructions e1 ept by the use ot the two speed machines and this involves loss of time in the low speed and is also not any too certain' in the result.

Now according to the preet invention the curbis done away with and Y:i breast section 9 is prox-'ideal upon the top of the basket. this section sloping uiinvardly and inwardly or beingsubstantially diagonal and provided with perforations similar to the wall 2 of the basket. lllithin the breast section 9 is a backing screen l() and a perforated? metal screen ll. The pei-foratodk breast section permits of the escape of the molasses :1t a point higher than the wall 2 and also at al point inwardly of the escape afforded' by the wall 2. inasmuch as the tendency is to climb, how'eveig the film of ther molasses upon the interior has free and ready escape tliroughthe perforated breast section. The metal' screen l-l within the breast section is preferably of finer mesh having G25 to 1,000 holes per square inch in order to 'etfectually check the rising of the sugar or the escape of the sugar through this breast section.

The' breast section will extend at an angle from 45 to GO degrees with respect to the horizontall and this angle is found to pron vide all ot the necessary resistance to climb ot the' charge afforded by the more or less right angular curb. The breast section is of substantial depth and this takes care of the curbingaction. The angle at which the breast section extends provides a substantial check against the risingr of the sugar charge and it also allows the charge tol grow thinner at the top only very gradually. rlhe result is that the sugar as indicated in Figure l will always be Within the upper portion of the breast section leaving a portion of this section open at all times tothe climbing film of in'olasse'swithin. This film will be evacuated through the perforated breast section and escape with the other molasses to the casing l. rlhe result is a thoroughly purged and dried sugar which can Without any bad result be dumped through the bottom opening el when the centrifugal is stopped without invoh'ing any remixing of 'he molasses therewith.

Referring to'Figure 2 a conical basket l2' is showin which progresses substantially evenly iioni a wide bottom toward a narrow top portion. ln this case the entire wall as it progressively narrows toward the top will interpose a check throughout its height to the creeping or climbing` of the charge and the charge will become thinner at the top due to the inclination of the wall. Consequentlv the film of the molasses will be afforded a constantly better and greater opportunity of escape as it climbs due to the "l action. r-rt the top of the conical bashet is alsoA a diagonal breast section l?) also perforated and this section, due to the con ical wail need not be so deep.

It will be found that through the use of a basket of this character the sugar will be more iniiform and of a better grade than where the molasses film was allowed to subsequently mix therewith. rllhe construction does not involve any particular departure from present centrifugal baskets and can be made to easily replace thev curb now a part of the basket-s.

lt is obvious that various changes and modifications may be made in the details of construction and design of the above 'specilically described embodiment of this invention without departing from the spirit thereof, such changes and'V modificationsbeing restricted only by thel sco Je of the following claim.

Tlf'hat is claimed iszrr centrifugal basket comprising a perfoi-atedy wall, a perforated breast section above said wall and projecting diagonally inwardly thereof and upuf'ardly therefrom, said wall and said section being' provided' with backing screens arranged therein and carried thereby, and perforated metal screens carried within both said backing screens. the perforated' metal screen in the basket being of substantially e0() to 625 holes per square inch and the perforated metal screen within the breast being from 625 to 1,000 holes per square inch. 4

FLOYD P. RENEMAN.

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