US3247021A - Method and apparatus for preparing massecuite for crystal extraction - Google Patents

Description

I 1966 c. R. STEELE ETAL METHOD AND APPARATUS FOR PREPARING MASSECUITE FOR CRYSTAL EXTRACTION Filed July 5, 1963 INVENTORS.

R. Sfeele Pr! 0 e Clarence Frank B. BY

ATTORNEYS United States Patent f 3,247,021 METHOD AND APIPARATUS FOR PREPARENG MASSECUHTE FQR (IRYSTAL EXTRACTEGN tClar-ence R. Stacie and Frank E. Price, Denver, Colo, assignors, by mesne assignments, to American Factors Associates, Limited, Honolulu, fiawaii, a corporation of Delaware Filed July 5, 1963, Ser. No. 292,948 18 Claims. (Cl. 127-15) This invention relates to a method and means for treating massecuite prior to extraction of its sugar crystal content.

As part of the refining of sugar, mixtures of sugar crystals and associated liquor are formed, usually comprising sugar crystals in mother liquor, or massecuite. In other operations, sugar magma is produced which is a mixture of sugar crystals in a foreign liquor. As used in the specification massecuite will be employed as a generic definition and sugar magma will be used as a species definition.

Under optimum conditions, sugar crystals will be formed at a ciystallizer stage, or the like, with as much of the sucrose as possible taken from solution and deposited as crystals. However, none of the commercial extractions are perfect and there is an economic limit on how far the extraction can be pursued. The quality of the massecuite produced in refining operations is variable and many cane sugar treatments produce what is termed a low-grade massecuite which is very viscous and difiicult to handle in modern equipment. In contradistinction, beet sugar refining usually produces massecuite having better flowability which permits continuous treatment in the refinery circuit and crystal separation in continuous centrifugals installed in such a circuit.

Accordingly, it is an object of this invention to provide a simple, eflicient and economical method of treating massecuite prior to crystal extraction to increase fiowability and improve sugar yield.

Another object of the invention is to provide a simple, efilcient and economical method of feeding viscous massecuite to a continuous centrifugal for promoting the separation of crystals from solution by the action of the centrifugal.

A further object of the invention is to provide a simple, economical and efficient crystallization treatment for massecuite for higher sugar crystal yield and reduced sugar content in solution.

Still another object of this invention is to provide simple, durable and efiicient apparatus for conditioning massecuite to promote crystal formation and increase flowability.

Yet another object of the invention is to provide simple, durable and eificient apparatus which may be automatically controlled to deliver conditioned massecuite to a continuous centrifugal so as to increase sugar extraction by the centrifugal.

The present invention provides several innovations in sugar refining practices. It recognizes the need for a conditioning treatment of a massecuite being delivered as feed to a continuous centrifugal. Such conditioning performs two useful functions. When massecuite is viscous, it tends to ball up on the screen of a continuous centrifugal, does not distribute uniformly over the screen and thus impairs the efliciency of the centrifugal separation. The conditioning step of the present invention utilizing a substantial degree of aeration with effective distribution of line air bubbles throughout the massecuite by the beating action of the agitator increases fiowability to a rather uniform degree and thus delivers feed which the centrifugal can separate at maximum efiiciency.

Also by such a conditioning treatment, the sucrose or 3,247,921 Patented Apr. 19, 19%6 ice sugar content of the liquor is reduced to a substantial degree with crystal buildup. As a result, a higher sugar yield is obtained from the massecuite in conjunction with efiicient separation of crystals from solution by the centrifugal action.

While the apparatus arrangement utilized in the conditioning treatment is relatively simple, it provides a highly efiicient conditioning treatment and such treatment may include automatic controls by which a predetermined level is maintained and a desired retention time is provided in conjunction with treatment in continuous flow. Such controls also regulate the rate of feed to the centrifugal which is not overloaded and operates at optimum efficiency.

The same apparatus may be utilized as a crystallizer stage in some treatments. In the past, attempts have been made to introduce air into conventional crystallizer treatments, but such air introduction may result in foaming with undesirable consequences. Frequently, the foam becomes so intense as to result in spillage and also impairs the efficiency of the equipment into which the crystallizer discharge is fed at the completion of the crystallization treatment. Further, such crystallization treatments have been in the nature of batch treatments, rather than continuous operation, whereas the apparatus of this invention may be utilized effectively in a continuous circuit with the efficiency of the crystallization controlled by the amount of gaseous input and the retention time in the mixing stage.

In this connection, it is possible to use gases other than air in such treatments, particularly carbon dioxide and nitrogen. In sugar beet processing, CO usually is available in the plant and may be piped to such crystallization stage. Aeration as provided by this invention avoids foam formation, as the beating action of the agitator breaks up any large bubbles tending to form and distributes the air or other gas uniformly throughout the body of massecuite in fine bubble formation. As a result, the aeration encourages crystal buildup with sucrose taken from solution that otherwise would remain in solution.

The practice of this invention will now be described with reference to the accompanying drawings. In the drawings, in the several views of which like parts bear similar reference numerals,

FIG. 1 is a front elevation of a typical installation utilizing features of this invention in the conditioning treatment of massecuite directed in continuous flow as feed to a continuous centrifugal unit;

FIG. 2 is a developed section through the mixing apparatus shown in FIG. 1 taken approximately on the line 2-2, and showing the massecuite level maintained in the mixer; and

FIG. 3 is a top plan view of the mixing apparatus shown in 1 1G. 1 taken approximately along the line 3-3.

FIG. 1 illustrates a typical assembly for conditioning massecuite as continuous feed to a continuous centrifugal stage. As shown, massecuite from a crystallizer stage or other source of supply (not shown) is delivered by a conduit 10 into the feed end of an elongated troughing member 11 open at its top and enclosed on its sides and ends for confining the flow of massecuite in the treatment zone. A shaft 12 carrying a series of blades 13 extends horizontally through the troughing member and is journalled for rotation in an external bearing 14 at the discharge end of member 11 and a submerged bearing 15 suspended by a rigid hanger 16 at the feed end. An electric motor and speed reducer 17 drive shaft 12 through suitable transmission 18.

Regulation of feed and discharge is provided to establish a liquid level 19 in troughing member 11 which exposes a substantial portion of blades 13 in the upper portion of each cycle of rotation and maintains the surface of the confined body of massecuite in contact with atmospheric air. In a preferred arrangement, alternate blades 13 are pitched at different angles so as to provide a greater degree of mixing of air and massecuite and to cause portions of the massecuite to be moved from lower portions of the contained charge to the upper portion thereof for exposure to atmospheric air.

The continued rotation of the shaft 12 and the action of the blades 13 carried thereby provides a progressive advance of material through the troughing member from its point of introduction through conduit 10. A sump outlet 23 is provided at the discharge end of the tank which directs the discharge into a conduit 24 at a rate determined by valve 28 as the feed to a continuous centrifugal 27. In the arrangement shown, the feed is regulated in relation to discharge with a level sensing device or member 25 relating flow through outlet 23 and setting a valve 26 in inlet conduit in accordance with such determination so as to maintain a uniform level 19 in troughing member 11.

From the foregoing, it will be apparent that in a circuiting arrangement such as shown in FIG. 1, provision is made to deliver conditioned massecuite at a desired rate into a continuous centrifugal 27 for separation of the sugar crystals from associated solution therein. The conditioning treatment satisfies two objectives, in that the flowability of the massecuite is increased so that it is in optimum condition for the separation action of the centrifugal. In addition, the combined aeration and agitation as provided in member 11 is effective in obtaining a final sugar extract from the solution which causes a buildup on sugar crystals already formed and results in the discharge of a solution having an extremely low sugar content.

The elongated troughing member 11 of FIG. 1 has been referred to in the preceding description as being open at its top particularly to supply atmospheric air in sufiicient quantity to provide the desired aeration in the beating action. If desired, the top of the troughing member may be covered to protect against deposit of any foreign matter and side or end openings may be provided to maintain sufiicient atmospheric air within the enclosure.

Also, when the troughing member is to be utilized in an operation in which gas other than atmospheric air is supplied, it will be desirable to have the top fully enclosed and side or end ports (not shown) provided for the introduction of such gas. For example, CO from a suitable plant source may be introduced at low pressure within such an enclosure and the gas supply will be used in sufficient quantity in the mixing action to eliminate the need for any exhaust arrangement. However, if desired, a pressure relief valve may be provided to prevent buildup of excess gas pressures.

One of the requirements of eflicient operation with continuous centrifugal apparatus is that the rate of feed to the centrifugal is controlled so as to permit optimum separation by the action of the centrifugal. As the characteristics of the feed to the centrifugal vary from time to time, a constant rate of feed is not satisfactory and in the practice of the present invention the feed to the centrifugal is delivered at a variable rate in accordance with a measurement of the power demand of the centrifugal so that less feed is introduced as the power demand exceeds an established or predetermined value and increases as the power demand becomes less than such value.

The circuiting arrangement for the feed control includes a lead connected to the centrifugal drive motor 29 and passing through a transformer 30 and connected to a transducer assembly 31 in which air is introduced at 32 and the current representative of the power demand of the centrifugal is changed from electrical energy to air pressure and the air pressure is directed into a pneumatic control 33 in connection with an adjusting device 34 regulating the setting of control valve 28. With this arrangement, if the power demand of motor 29 is less than an established standard, valve 28 will be opened slightly and if the power demand is more than the standard, the valve setting will be changed to reduce the flow into the centrifugal. Valves 35 and a gauge 36 in the transducer assembly permit operator control in addition to the automatic control of the normal operation of the circuit described above.

We have found that it sometimes is advantageous to the treatment to recirculate a portion of the syrup discharge of the centrifugal into the troughing member for mixing with the incoming massecuite. Such syrup intro* duction provides a quick thinning effect which is particularly desirable when a highly viscous massecuite is being treated. A preferred arrangement for providing such action has been illustrated in FIG. 1. Syrup discharge through the syrup outlet 40 of centrifugal 27 is delivered into a suitable tank or receptacle 41 having means for dividing the flow, with one fraction passing from the centrifugal stage through an outlet 42 and another fraction is discharged into the intake end 43 of a centrifugal pump 44 from which it is conducted through a conduit or line 45 into the feed end of troughing member 11. Preferably line 45 is valve controlled as shown at 46 so that the total feed to member 11 can be balanced to the discharge through outlet 23 in the manner previously described.

Even when a highly viscous massecuite is being treated in such a circuit, the discharge through outlet 23 will have a high degree of fiowability and by recycling a portion of the syrup or sugar solution discharge of centrifugal 27 through the line 45 to the troughing member 11, the incoming massecuite delivered into the troughing member through conduit 10 is promptly mixed with the return material and the mixture is quickly brought to a more flowable condition by the beating action of blades 13 so that it receives a more intense beating and agitation, coupled with aeration in its progressive movement through the troughing member.

In the preceding description, different operating prac= tices have been described, some or all of which may be utilized in a given plant operation. A significant feature of the aeration and beating of massecuite or sugar magma is that the feed may be introduced into the treatment at prevailing temperatures and thus does not require special preparation for the treatment practices of this invention.

In preferred practice, the massecuite or sugar magma is treated in a confined zone in continuous flow with aerating gas maintained or circulated in contact with the flow along the course of treatment. Such material with or without extraneous syrup is introduced at the upstream end of the course and discharged at the downstream end under controls which balance input volume to the volume of discharge thereby maintaining a uniform liquid level in the treatment. Consequently, by employing a troughing member of substantial length and a series of beating stages along its length, a substantial quantity of air or other aerating gas is distributed in the massecuite or magma increasing its flowability along the course and providing suificient contact between the gas and solution so that the sucrose content in solution is substantially decreased.

When the massecuite preparation is utilized to control the feed volume and consistency to a separation stage, such as a continuous centrifugal, such feed can be prepared in optimum condition for such separation. Also, where desired, automatic control may be provided in which the power demand of the centrifugal is the factor determining the feed control. Also, in such an installation, extraneous solution may be circulated to the mixing and conditioning treatment from the syrup discharge of such centrifugal.

Finally, in some treatments, the sucrose extraction from the associated liquor may be utilized to eliminate a crystallizer stage ahead of the conditioning stage of this invention and the fact that the treatment may be performed at prevailing temperature makes such circuiting practice desirable in some plants.

We claim:

1. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is deceased, and continuously discharging the aerated flow after a predetermined treatment interval in said zone as feed directly into a continuous centrifugal separation stage.

65,. The method of preparing massecuite for crystal ex traction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, maintaining a uniform massecuite level in said zone by balancing the volume of input to the volume of discharge from said zone, and continuously discharging the aerated flow after a predetermined treatment intenval in said zone as feed directly into a continuous centrifugal separation stage in said zone.

3. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous fiow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining circulating air above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the air above said flow and thereby inducing entrainment of air into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and continuously discharging the aerated flow after a predetermined treatment interval in said zone.

4. The method of preparing massecuite for crystal extraction, which comprising moving massecuite passing from a crystallization stage in continuous ilow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining circulating CO above and in contact With the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the CO above said flow and thereby inducing entrainment of CO into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and continuously discharging the aerated'flowafter a predetermined treatment interval in said zone as feed directly into a continuous centrifugal separation stage.

5. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the How along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and discharging the aerated massecuite after a predetermined retention interval as the feed to a continuous centrifugal separation stage.

6-. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the fiow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and discharging the aerated massecuite after a predetermined treatment interval as feed at a controlled rate to a continuous centrifugal separation stage.

7. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage at prevailing temperatures in con tinuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is prorgessively increased and the sucrose content in solution is decreased, and continuously discharging the aerated flow after a predetermined treatment interval in said zone as feed directly into a continuous centrifugal separation stage.

8. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, maintaining a uniform massecuite level in said zone by balancing the volume of input to the volume of discharge from said zone, continuously discharging the aerated flow directly into a centrifugal separation stage, and recycling some of the separated syrup of the separation stage into the massecuite flow adjacent its upstream end.

9. The method of preparing massecuite for crystal extraction, which comprises moving massecuite and extraneous syrup passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby fiowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and continuously discharging the aerated flow after a predetermined treatment interval in said zone as feed directly into a continuous centrifugal separation stage.

10. The method of preparing massecuite for crystal extraction, which comprises moving massecuite and extraneous syrup passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alte-rnately into the flow of massecuite and into the aerating gas above said how and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, continuously discharging the aerated fiow directly into a centrifugal separation stage, recycling some of the separated syrup of the separation stage at a controlled rate into the massecuite flow adjacent its upstream end, and maintaining a uniform massecuite level in the treatment zone by balancing the volume of input material to the volume of discharge from said zone.

11. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining circulating nitrogen above and in contact with the fiow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the nitrogen above said flow and thereby inducing entrainment of nitrogen into the massecuite flow as fine bubbles, whereby flowability of the massecuite is progressively increased and the sucrose content in solution is decreased, and continuously discharging the aerated flow after a predetermined treatment interval in said zone as feed directly into a continuous centrifugal separation stage.

12. The method of extracting the sucrose content from mother liquor in the treatment of massecuite in a continuous flow through a confined zone of substantial extent which comprises directing the continuous flow of massecuite passing from a crystallization stage along an enclosed course subject to continuous feed and discharge and in contact with a confined body of aerating gas, inducing entrainment of the aerating gas into the massecuite flow in fine bubble formation by beating the massecuite in a succession of stages by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby, whereby crystal formation in the massecuite is increased by sucrose extraction from associated solution, and continuously discharging aerated massecuite'after a predetermined mixing in said flow as feed directly into a continuous centrifugal separation stage.

13. The method of extracting the sucrose content from liquor in the treatment of sugar magma in a continuous flow through a confined zone of substantial extent which comprises directing the continuous fiow of magma along. an enclosed course subject to continuous feed and dis-- charge and in contact with a confined body of aerating gas,.

inducing entrainment of the aerating gas into the magma flow in fine bubble formation by beating the magma in a succession of stages by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of magma and into the aerating gas above said fiow and thereby, whereby crystal formation in the magma is increased by sucrose extraction from associated solution, and continuously discharging aerated magma after a predetermined mixing in said flow as feed directly into continuous centrifugal separation stage.

14. Apparatus for preparing massecuite for crystal extraction, comprising an elongated troughing member open at its top and enclosed on its sides and ends for confining a horizontal flow of massecuite and a body of aerating gas above said flow, a valve-controlled outlet at the downstream end of the troughing member for regulating the rate of outflow of treated massecuite from said member, means for passing the treated massecuite from said outlet as feed directly into a continuous centrifugal separation stage, means for feeding massecuite passing from a crystallization stage into said member at its upstream end at a controlled rate related to the discharge rate and determining a liquid level therein, a rotary shaft extending lengthwise through the interior of the troughing member and carrying a plurality of blades at intervals throughout its length rotating in close proximity to the bottom of the member and above the liquid level in each cycle of rotation for beating the flowing massecuite and entraining air in fine bubble formation therein so as to increase flowability of the massecuite, and drive means for rotating said shaft.

15. Apparatus for preparing massecuite for crystal extraction, comprising an elongated troughing member open at its top and enclosed on its sides and ends for confining a horizontal How of massecuite and a body of aerating gas above said flow, a valve-controlled outlet at the downstream end of the troughing member for regulating the rate of outflow of treated massecuite from said member, means for passing the treated massecuite from said outlet as feed directly into a continuous centrifugal separation stage, sensing means for relating the rate of flow through said outlet to the liquid level in the troughing member, means for feeding massecuite passing from a crystallization stage into said member at its upstream end at a controlled rate established by the sensing means and determining a liquid level therein, a rotary shaft extending lengthwise through the interior of the troughing member and carrying a plurality of blades at intervals throughout its length rotating in close proximity to the bottom of the member and above the liquid level in each cycle of rotation for beating the flowing massecuite and entraining air in fine bubble formation therein so as to increase flowability of the massecuite, and drive means for rotating said shaft.

16. Apparatus for preparing massecuite for crystal extraction, comprising an elongated troughing member open at its top and enclosed on its sides and ends for confining a horizontal flow of massecuite and a body of aerating gas above said flow, a valve-controlled outlet at the downstream end of the troughing member for regulating the rate of outflow of treated massecuite from said member, means for passing the treated massecuite from said outlet as feed directly into a continuous centrifugal separation stage, sensing means for relating the rate of flow through said outlet to the liquid level in the troughing member, means for feeding massecuite passing from a crystallization stage into said member at its upstream end at a controlled rate established by the sensing means and determining a liquid level the-rein, a rotary shaft extending lengthwise through the interior of the troughing member and carrying a plurality of blades at intervals throughout its length rotating in close proximity to the bottom of the member and above the liquid level in each cycle of rotation for beating the massecuite and entraining air in fine bubble formation therein so as to increase flowability of the massecuite, and drive means for rotating said shaft.

17. Apparatus for preparing massecuite for crystal extraction, comprising an elongated troughing member open at its top and enclosed on its sides and ends for confining a horizontal flow of massecuite and a body of aerating gas above said flow, a valve-controlled outlet at the downstream end of the troughing member for regulating the rate of outflow of treated massecuite from said member, means for passing the treated massecuite from said outlet as feed directly into a continuous centrifugal separation stage means for feeding massecuite passing from a crystallization stage into said member at its upstream end at a controlled rate related to the discharge rate and determining a liquid level therein, a rotary shaft extending lengthwise through the interior of the troughing member and carrying a plurality of blades at intervals throughout its length rotating in close proximity to the bottom of the member and above the liquid level in each cycle of rotation for beating the flowing massecuite and entraining air in fine bubble formation therein so as to increase flowability of the massecuite, the blades at alternate intervals being pitched differently than the blades intermediate said intervals, and drive means for rotating said shaft.

18. The method of preparing massecuite for crystal extraction, which comprises moving massecuite passing from a crystallization stage in continuous flow through a confined treatment zone of substantial extent subject to continuous feed and discharge, maintaining aerating gas above and in contact with the flow along its course of travel through said zone, subjecting such flow to a succession of beating actions by a series of material contacting members spaced longitudinally throughout the extent of said confined treatment zone and passing alternately into the flow of massecuite and into the aerating gas above said flow and thereby inducing entrainment of gas into the massecuite flow as fine bubbles, whereby fiowability of the massecuite is progressively increased and the sucrose content in solution is decreased, maintaining a uniform massecuite level in said zone by balancing the volume of input to the volume of discharge from said zone, continuously discharging the aerated flow into a continuous centrifugal separation stage, and regulating the discharge into the centrifugal separation stage in accordance with a measurement of the power demand of said centrifugal separation stage.

References Cited by the Examiner UNITED STATES PATENTS 242,216 5/1831 Morrell 127-2 X 675,938 6/1901 Delafond 12 7-58 988,261 3/1911 Griere 127-58 1,334,395 3/1920 Patterson 127-22 1,862,719 6/1932 Spreckels 12760 2,032,160 2/ 193-6 Widmer 127-58 2,206,237 7/ 1940 Roberts 127-64 X 2,347,288 4/ 1944 Schle-gel et al 127--l 5 FOREIGN PATENTS 310,369 3/ 1929 Great Britain. 570,101 6/ 1922 Great Britain.

OTHER REFERENCES Honig, Principles of Sugar Technology, vol. III, Crystallization, Elseview Publishing Co., New York, 1959, pp. 3-454.

Spencer-Meade, Cane Sugar Handbook, eighth edition, 1945, John Wiley and Sons, New York, pp. 207-216 and 2262 29.

MORRIS O. WOLK, Primary Examiner.

Claims (1)

14. APPARATUS FOR PREPARING MASSECUITE FOR CRYSTAL EXTRACTION, COMPRISING AN ELONGATED TROUGHING MEMBER OPEN AT ITS TOP AND ENCLOSED ON ITS SIDES AND ENDS FOR CONFINING A HORIZONTAL FLOW OF MASSECUITE AND A BODY OF AERATING GAS ABOVE SAID FLOW, A VALVE-CONTROLLED OUTLET AT THE DOWNSTREAM END OF THE TROUGHING MEMBER FOR REGULATING THE RATE OF OUTFLOW OF TREATED MASSECUITE FROM SAID MEMBER, MEANS FOR PASSING THE TREATED MASSECUITE FROM SAID OUTLET AS FEED DIRECTLY INTO A CONTINUOUS CENTRIFUGAL SEPARATION STAGE, MEANS FOR FEEDING MASSECUITE PASSING FROM A CRYSTALLIZATION STAGE INTO SAID MEMBER AT ITS UPSTREAM END AT A CONTROLLED RATE RELATED TO THE DISCHARGE RATE AND DETERMINING A LIQUID LEVEL THEREIN, A ROTARY SHAFT EXTENDING LENGTHWISE THROUGH THE INTERIOR OF THE TROUGHING MEMBER AND CARRYING A PLURALITY OF BLADES AT INTERVALS THROUGHOUT ITS LENGTH ROTATING IN CLOSE PROXIMITY TO THE BOTTOM OF THE MEMBER AND ABOVE THE LIQUID LEVEL IN EACH CYCLE OF ROTATION FOR BEATING THE FLOWING MASSECUITE AND ENTRAINING AIR IN FINE BUBBLE FORMATION THEREIN SO AS TO INCREASE FLOWABILITY OF THE MASSECUITE, AND DRIVE MEANS FOR ROTATING SAID SHAFT.

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