US2426126A - Method and apparatus for affining sugar - Google Patents

Description

Aug-19,1947- G. E. STEVENS 2,426,126

METHOD AND APPARATUS FOR AFFINING SUGAR Filed March 16, 1944 INVENTOR 650965 E. STEVE/V5 BY wlw ATTORNEYs Patented Aug. 19, 1947 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FGR AFFINING SUGAR George E. Stevens, Denver, Cola, assignorto The Western States Machine Company, Hamilton, Ohio, a corporation of Utah Application March 16, 1944, Serial- No; access 11 Claims. 1

This invention relates to the aflination of raw sugar or the like, by which is meant the removal of relatively impure adherent molasses or syrupfrom the sugar grains. V

Afiination processes have been carried out heretofore in sugar factories and refineries by mixing and mingling .a suitable affination syrup with the impure sugar so as to form a magma susceptible to treatment in centrifugal machines, and then subjecting the magma to centrifugal purging and washing operations. Washed sugar of about 99' to 995 purity is thus produced. This sugar is melted and used for the production of high purity massecuites.

Processes of this known type require complex equipment installations, and are costly to operate. Provisions must be made for preparing, storing and handling the afiin-ation syrups, as well as the green syrups and wash syrups produced from the centrifugal machines Bulky mixin and mingling equipment is required, and the centrifugals are costly and entail large ex penses for labor and motive powerl An object of my invention is to provide a new process and new apparatus by which to simplify and reduce the cost of afiining sugar. Another object is to provide a continuous afiination process. Further objects are to provide an affination process and apparatus for producing the same which eliminate the use of afiination syrup and attendant complications; which do not require the use of centrifugal machines which decrease the power requirements in affination work; and which reduce the labor required per ton of sugar afiln'ed.

According to the present invention, the affination of raw sugar and the like is carried out by treating the sugar with a heated aqueous atmosphere, such as an atmosphere of wet steam, so as to deposit moisture upon and liquefy the molasses films on the sugar grains and thus produce a syrup which can be drained from the sugar and recovered separately therefrom by gravity flow. The combined actions of" heat andmoisture inan aqueous atmosphere have been: found effective under proper conditions to liquefy and enable the removal of so much of the adherent molasses-that ordinary raw sugar of about 96 polarization can be afilned readily to a purity of 99 to 995, more or less, without requiring the use of either afiination' syrup or centrifugal maclfines.

In practice, a stream of the sugar to be afiined' preferably is passed through an elongated treating zone in countercurrent relation to an atmosphere substantially saturated with wet steam;

and during its travel the sugar is continually lifted and showered through the steam so that water condenses and collects upon the sugar" grains. The adherent molasses thus becomes liq.- quefied and is sweated off of the sugar cr stals; from which theresulti'ng. syrup is caused to now to a point of'separate recovery. V

The treatment zone may be provided by one or more elongated rotary drums mounted in an inclined position so as tohandle the impure sugar' in a manner analogous. to the handling of refined sugar in well-known "granulatom' drums; Where two or more drums are used they are arranged in a communicating series, and provisions are made for feeding the impure sugar into the upper end of the first drum, and for recovering") treated or afiined sugar continuously from the lower end of the last drum. Eachdrum is made with a long perforate wall or screeri port'ionhaving interior baflles or fins whichnnrota't ing, con} tinually lift the sugar to the top of the drum and shower it across the interior space to the bottom thereof. A' stationary housing or shell surrounds and encloses the perforate wall portion. to prevent the escape of steam and also to collect the syrup sweated from the sugar grains, which syrup passes through the drum perforations to the interior to the shell and then drains by gravity to an outlet in the'shell. V

The drum rotation preferably is fast enough: to produce an appreciable centrifugal force which aids the force of gravity in removing liquefied syrup from the sugar grains and discharging this syrup through the drumscreerl. I

A steamchamber preferably communicates; with the lower end of each drumv andis supplied with low pressure exhaust steam from suitable steam injection means, The resulting aqueous atmosphere is drawn through the by the action of suction means communicatingwith its upper end. Suitable provisions also are made-for regulating the temperature and the humidity Oftilis atmosphere.

The foregoing. and other objects, features and advantages of "my invention will become apparent from the following detailed descriptionyof a-I-1-i 1f lustrative embodiment thereof, when considered in connection with the accompanying drawings. in which I I Figure 1* is a diagram illnstratihg a plant in.. stallation suitable for practicing the invention;

Figure 2' is a cross-section through one of thedrums, showing thescreen portion and thesurrounding stationar housing.

In th illustrated embodiment, raw sugar to be affined is passed from a bin A through a treatment zone comprising two stages B and C, whence affined sugar is delivered to a chute D for Dassage to a melter wher the sugar is made into a liquor for further refining. Substantially the same apparatus and operations may be used at each of the two stages.

For example, an elongated cylindrical drum I is mounted in an inclined position for rotation on rollers H, induced by driving means l2. The drum preferably is rotated at a speed of at least 30 R. P. M.; for example, at 50 to 60 R. P. M. or even faster. Intermediate its ends the drum has a long perforate wall or screen portion I4 which is surrounded and enclOsed by a stationary cylindrical shell Hi. This wall portion, for example, may be made of No. l (.027 inch) perforated screen material. Fins l insid the same continually lift and shower the sugar during thedrum' rotation.

The upper end portion of each drum communicates withan exhaust chamber H, which in turn communicates with a spray tower l8 having an oiftake l9 at the top, leading to asuction fan (not shown), and a bottom oiftake 2D to drain away liquid produced in the tower from a cold water spray device 2| and from the condensation of steam by the action of the cold spray.

' The lower end of each drum communicates With a steam chamber 30, to which wet steam, such as low pressure exhaust steam, may be supplied through an injection device 3|. Air also may be admitted to the steam chamber, and superheated water may b released through a device such as 3| to produce an aqueous atmosphere. Heating means, such as radiator steam coils 32, preferably extend across the steam chamber to facilitate control of the temperature of the atmosphere supplied through the rotating drum. A suitable humidity control 33 of known construction, responsive to a bulb 34 in the steam chamber, may be provided to regulate the humidity of the treating atmosphere by regulating the supply of steam or the like from the injection device 3|. A suitable temperature controller 35 of known construction, responsive to a bulb 36 disposed in the steam chamber, may be provided to regulate the temperature of the atmosphere by controlling the supply of live steam to thecoils 32.

A perforated pipe 40 extends along the top of each drum screen in position to direct jets of air or steam under pressure against the rotating screen, for the purpose of keepin it sufficiently clean and free from crusts. Steam may be admitted to pip 40 through a branch pipe 4|, and air through a branch pipe 42, at a pressure in pipe 40 indicated by a gauge 43.

A semi-cylindrical shield 50, disposed along the upper half of each housing I6 between it and the screen portion [4, protects the upper part of the housing against accumulations of syrup. The two housings have outlets '52 and 53, respectively, at their lower ends, through which syrup discharged through each drum screen and collected in each housing may be drained away for appropriate treatment.

At the lower end of the first drumthat in stage B-a chute 54 is arranged to carry partially treated sugar from this stage to the head or upper end of the rotary drum H3 in stage C, A chute 56 delivers raw sugar from the bin A into the upper end of the first drum at a regulated rate determined by the speed of a feed screw 5! driven by a variable speed drive 58.

In operating the illustrated installation, raw sugar is fed at a regular rate by screw 5'! into the upper end of the first drum, and passes in a continuous stream through this drum while being repeatedly lifted and showered through the space therein by the action of the rotating fins l5. At the same time a heated atmosphere substantially saturated with water vapor passes through the drum in countercurrent relation to the sugar stream, from the steam chamber 30 to the exhaust chamber [1, tower l8, and oiftake [9. Water thus is caused to collect upon the sugar from the ambient aqueous atmosphere, which also heats the molasses films on the sugar crystals, and in consequence the adherent molasses is liquefied and is then caused to separate from the sugar by the force of gravity, as supplemented by the centrifugal force produced by the drum rotation. The syrup so produced passed through the perforations of the screen portion l4 to the shell l6, and then flows to the outlet 52.

Meanwhile partially treated sugar issuing from the lower end of the drum in stag B passes through chute 54 into the upper end of the rotary drum in stage C, and the same manner of treatment is repeated in this latter stage. The sugar discharged from the lower end of the second drum passes through chute D, which carries it to the melter for further refining. The syrup produced by the removal of molasses in stage C is carried away through the housing outlet 53. This syrup has a higher purity than the syrup produced in stag B, and the separate recovery of the two syrups through outlets 52 and '53, respectively, permits each syrup fraction to be treated in the manner best suited for the efficient recovery of the sugar values it contains.

The liquid produced from the cold spray and condensation in towers l8 may be conducted by gravity to the melter, if desired, for use as a solvent for the afiined sugar discharged through chute D.

Throughout the operations a suitable cleaning atmosphere, such as exhaust steam introduced with a certain proportion of compressed air, is supplied through the perforated pipe lines 46 along the top of the revolving screens. This not only cleans the screens but also serves to some extent as a Washing medium to aid the removal of molasses films from the sugar.

Several important advantages may be achieved by the use of the present invention in place of known ailination systems: An arrangement similar to that illustrated, using two drums each having a screen portion eighteen feet long b six feet in diameter, should afiine about 500 tons of raw sugar per day, thus doing the work of a modern affination station using four high-speed centrifugal machines. Only one operator would be required. The use of afiination syrup would be eliminated, thus greatly simplifying the process and reducing costs and equipment requirements. The motive power required to operate the installation would be only a fraction of that necessary for affination installations using centrifugal machines. In addition, various other savings of equipment and operating costs are made possible, as well as other advantages which reside in the continuous and simplified natureof the new operations.

It will be apparent 'thatthe features herein disclosed may be embodied in many different forms of apparatus and practiced in various ways, and I therefore desire that the invention be accorded a scope fully commensurate with its contributions to the art, which are intended to be defined by the appended claims.

I claim:

1. The method of affining sugar coated with molasses which comprises showering the same through a heated aqueous atmosphere of wet steam until moisture formed by condensation of said steam has collected upon and liquefied the molasses coating, and separating the resulting syrup from the sugar grains.

2. The method of affining sugar coated with molasses which comprises showering the same through an atmosphere of Wet steam until water formed by condensation of said steam has collected upon and liquefied the molasses coating, and draining the so liquefied molasses away from the sugar.

3. The method of afiinin raw sugar which comprises showering the same continually through a countercurrent stream of wet steam until the moisture of the steam condensed by the cooling effect of the sugar has liquefied the molasses coating of the raw sugar, and simultaneously draining syrup so produced away from the sugar.

4. The method of afiining impure sugar which comprises passing a stream of the same through an elongated treatment zone while continually lifting the sugar and showering the same across said zone and simultaneously passing an atmosphere of wet steam through said zone to deposit Water upon and liquefy molasses adhering to the sugar grains, and draining the so liquefied molasses away from the sugar grains.

5. The method of affining impure sugar which comprises passing a stream of the same through an elongated treatment zone, passing an atmosphere of wet steam through said zone countercurrent to the sugar stream, continually showering the sugar through the steam within said zone, continually rotating the sugar within said zone to supplement the force of gravity acting thereupon by centrifugal force, and simultaneously draining away the syrup so produced and removed from the sugar.

6. The method of affining impure sugar which comprises passing a stream of the same through a rotating drum having a long perforate wall portion so as continually to rotate the sugar in and shower it across the space within the drum, simultaneously passing an atmosphere of wet steam through the drum to deposit water upon and liquef molasses adhering to the sugar grains, and discharging molasses so liquefied throu h openings in said perforate wall.

7. The method of affining impure sugar which comprises passing a stream of the same through an elongated treatment zone having at least two distinct stages, passing an atmosphere of wet steam through each of said stages and continually showering the sugar through the steam within each stage, thereby causing water to collect upon and liquefy molasses adhering to the sugar grains,

flowing the resulting syrup away from the sugar grains in each stage, and collecting such syrup produced in a first stage of said zone separately from such syrup produced in a later stage of said zone.

8. Sugar affination apparatus comprising a rotary drum formed with a long perforate wall portion having openings to drain syrup therethrough, a stationary shell surrounding and enclosing said portion to collect such syrup, means at one end of said drum for feeding sugar thereinto, means in said drum acting upon its rotation to lift said sugar and shower it downward through said atmosphere, and means for supplying a heated aqueous atmosphere through said drum to contact the sugar therein, means at the other end of said drum to receive and conduct sugar therefrom, and means for draining syrup from said shell.

9. Sugar affination apparatus comprising a plurality of inclined rotary drums arranged in a communicating series and each formed with a long perforate wall portion, a stationary shell surrounding and enclosing each perforate wall por tion, means to feed a stream of sugar into the upper end of the first drum, means inside each drum for lifting and showering the sugar passing therethrough as the drum rotates, means adjacent the lower end of each drum for supplying a heated aqueous atmosphere thereinto, means for recovering syrup from each of said shells, and means for recovering treated sugar from the lower end of the last drum.

10. Sugar afiination apparatus comprising a rotary drum formed with a long perforate wall portion having openings to drain syrup therethrough, a stationary shell surrounding and enclosing said portion to collect such syrup, means at one end of said drum for feeding sugar thereinto, means for supp-lying a heated aqueous atmosphere through said drum to contact the sugar therein, means in said drum acting upon its rotation to lift said sugar and shower it downward through said atmosphere, means at the other end of said drum to receive and conduct sugar therefrom, means for draining syrup from said shell, and means for regulating the temperature and the humidity of said atmosphere.

11. Sugar affination apparatus comprising a rotary drum formed with a long perforate Wall portion having openings to drain syrup therethrough, a stationary shell surrounding and enclosing said portion to collect such syrup, means at one end of said drum for feeding sugar thereinto, means for supplying a heated aqueous atmosphere through said drum to contact the sugar therein, means in said drum acting upon its rotation to lift said sugar and shower it downward through said atmosphere, means at the other end of said drum to receive and conduct sugar therefrom, means for draining syrup from said shell, and means extendin along said perforate Wall portion between it and said shell for directing cleaning fluid jets against said perforate wall portion.

GEORGE E. STEVENS.

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

UNITED STATES PATENTS

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