US2633435A - Sugar crystallizer - Google Patents

Description

March 31, 1953 E. w. KOPKE 2,633,435

v SUGAR CRYSTALLIZER Filed Nov. 28, 1949 3 sheets-sheet 1 March 31, 1953 E. w. KOPKE i 2,633,435

v SUGAR CRYSTALLIZER.

Filed Nov. 28, 194e s sneets-sheets 5o fn,"

Err/msi: WHODH wigs@ yearn-w auw! Patented Mar. 31, 1953 UNITED STATES PATENT OFFICE SUGAR CRYSTALLIZER Ernst W. Kopke, New York, N. Y. Application November 2s, 1949, serial No. 129,727

' 18 Claims. 1

This invention relates to crystallizers and more particularly to crystallizers used in the development -of crystals in massecuite. The massecuite resulting from certain operations in the making of sugar is dropped hot into the sugar crystallizing apparatus and there is stirred while it is being cooled and the sugar crystals are developed. Many proposals, some of which have gone into commercial use, have been made for crystallizing sugar more rapidly from the massecuite. Crystallizer capacity and performance that was regarded as satisfactory in the past twenty years is now admittedly unsatisfactory. The objective has always been to cut down the time in crystallization to the smallest possible amount compatible with proper development of the sugar grain. To attain this objective, rapid uniform cooling is necessary. To secure uniform cooling, the massecuite is continuously circulated to bring all portions repeatedly into contact with the cooling coils while avoiding the development of stagnant pockets or zones in the material. For minimum time for crystallization, the largest amount of cooling surface possible must be provided without interfering with the stirring of the massecuite.

Therefore it is an object of my invention to provide larger amounts of cooling surfaces for the massecuite together with adequate means to circulate and stir the massecuite.

Heretofore it has been common to treat massecuites in crystallizers by the batch method. The whole mass of massecuite would be dumped into the crystallizer and cooled therein until it was judged that the practical maximum of crystallization and cooling had been attained. The mass would then be dumped into a storage or mixing tank to be treated and processed further. This batch treatment resulted in large amounts of the material being tied up in the process. Furthermore while one batch was being treated in a crystallizer, others had to be stored and treated as accummulated, and additional crystallizers had to be provided thus entailing increased investment in equipment.

It is another object of my invention to provide apparatus for crystallizing sugar on a continuous basis wherein the massecuite enters at one end of the crystallizing apparatus and is continuously treated and discharged at the other end.

As the end of the crystallization period is reached, the mass of sugar syrup and crystals becomes increasingly viscous, so much so that it cannot be effectively treated in later stages of processing without its viscosity being lowered by adding additional liquid or by heating or both.

Therefore it is another object of my invention to provide a continuous crystallizer with means for reheating the massecuite at the end of the crystallization process in order that it may be in better condition for further treatment.

Other objects and advantages of the invention will become apparent as it is described in connection with the accompanying drawings.

Figure 1 is a side elevation view partly in section of my new continuous crystallizer;

Figure 2 is a plan view of the crystallizer of Fig. l;

Figure 3 is an end section View ofthe crystallizer of Fig. 2;

Figure 4 is an enlarged elevational section View of one of the units of the crystallizer of Figs. 1-3.

Referring to the drawings, a tank designated generally by the numeral l0 comprises fiat parallel side walls I2 and I4 and parallel end walls I3 and I5 and a bottom wall. The whole tank is relatively long so that massecuite may enter through an entrance chute I6 at one end and discharge over a discharge lip I1 at the opposite end after treatment as will be more fully described.

Stirring apparatus is provided along the tank. The apparatus may be in the form of similar units spaced from one another along the length of the tank, the number of units being governed by the conditions of use. For many if not most purposes, two units for cooling will be sufficient with a third unit at the exit end forreheating since in the ordinary process of crystallization the massecuite becomes cool and viscous toward the end of crystallization and has to be reheated in order to be treated further in the sugar making process. Indeed it may be necessary in some cases to reheat in order to move the massecuite out of the crystallizer.

Since the units are identical only one need b described. Each of the units I, Il and III may comprise a plurality of horizontal parallel pipes wound sinusoidally in a vertical direction and arranged preferably in four sets of coils 2|, 22, 23 and 24. These coils of pipes are mounted in such a way that they may be rocked up and down in an arc of a circle. The coils are mounted on two spaced inverted U-shaped plate members designated generally by the numeral 30. These plate members are iixedly mounted on a horizontal rock shaft 25 passing through the middle of the transverse arms 32 of the U-members.

The rock shafts are preferably mounted in bearings 26 supported from the side walls I2 and I4 of the tank or otherwise suitably supported. The coils of pipes are mounted on opposite sides of the substantially parallel arms 3l, 33 of the U-members so that the coils 2I and 22 are spaced by the width of the arm 33 and the coils 23 and 24 are spaced by the width of the arm 3|. Thus the coils 2:I, 22 'are spaced by the length of .the transversearm 32 from the sets 23,24.

In order to cause rocking movement of the shaft 25 and the U-members carried thereby and consequently arcuate motion of .the coils, one end of the rock shaft 25 is extended nutside the tank and has xedly mounted 'thereon `a lever 40. To the free end of the vlever 45, la connecting rod 42 is pinned 'by apin 4I. The other end of the connecting rod is connected with a rotating disc or plate member 43. The disc 43 mounted on an extending end of a stirring shaft 44 .passing .horizontally through the side walls I2, I4 of the tank parallel .to and below .the rock shaft`2 5. .It will be observed .therefore lthat as the disc 43 rotates, it carries with it the .connecting .rod 42 which in turn causes the lever Y40 and the rockshaft .25 to rock.

.This...rocking motion .of the U-members ,and the. coils carriedthereby causes the coils to ccntinuously .move through the massecuite and .henceto cool .'itas it passes along the crystal- 'lizertowar'd -the exit end thereof. The rocking .motion also tends .to agitate and. stir up .the massecuite.

.In order Ato .improve .the `heat transfer or cooling function of the tubes of the coils-2l, 22,23 .and 2.4, .the various .tubes-of these vcoils are each fprovided with .a .series of radial (fins 21. The fins may each Ybe in the form of round thin .metal .plates welded to A.the tubes. Preferably thedns .onone .tube will he .offset or staggered :relativelyto .the .fins .on .an .adjacent tube. In .thisway,.intimate contact between the massecuite .and the v.'ns of .the cooling .coils is accomplished .so that as the .massecuite .passes through the .plane of acoil, .it is effectively cooled by said intimate contact. The ns do more than merely cool the massecuite. YThey more effectivelystir and mix .it.

VV'In .units .I .and I'I, the cooling water .enters lthe .coil -2I at the top .through an inlet pipe '.50 .having a control valve .52 therein. A rubber vhose or.other suitable .flexible connection .rather .than .a .flexible joint with packing .and glands is preferred between the stationaryinlet pipe 50 .and the .coil 2l. .At the bottom rof the coil 2l, 'itisjjoinedto the coil 2'2, the top of 'the coil 22 being ,joined tothe tQp coil 23 while .the bottom of the coil -23 is joined to the bottom o'f coilV 24. The cooling waterfex'itis .through'a' pipe "from the'top of the .cooling coil24 'through a "fiexible Aconnection to the `outlet pipe 58 and then into a trough or outlet tank 59. By this arrangement ofcooling'coils `andpassage of cool- "ing water the warmest portion of the massecuite -willcome in engagement with the warmest porition ofthe cooling Icoils. This tends to even 'the temperature `differential between the masse- 'cuite as itis cooled-and passes along the crystallizer. `If the `cool water entered the rst coil 24 there would be less `cooling at coil 2l and' *hence the massecuite would have been made needlessly viscous when the coils are connected 'in-series.

lAlternatively, in order to expedite the first "stage of cooling the coils *23, 24 may be connected for separate inlet and outlet pipes and so also may the coils 2I and 22.

As another alternative, the coils 23, 24 may be connected in series and fed separately from the coils 2I and 22; and the latter also may be connected in series and separately fed. In this alternative, the last coil of each series Will have the cool Water fed to it first, for reasons similar to those .already given.

In order itc fstirand moveithe massecuite within the compass of the inverted U-members and *..between the coils 22 and 23, a series of stirring blades 45, 43 are provided upon the stirring shaft A44. lThey may extend in diametrically opposite :directionsfrom shaft 44 and the blades 45 on one end of the shaft 44 are inclined or turned at 'an angle to 'the .length of the tank so as to move .the massecuite inwardly. The stirring blades 46 on the other end of the stirring shaft 44 are turned vat .an oppositeangle so as .to cause the massecuite to move inwardlyfrom the other side of the tank. Thus the massecuite at the 'sidewalls .of .the 'tank Which would tendto `cool by reason of contactwith the sidewalls is constantly moved inwardly by the stirring blades 45 and "46. At the `4same time, it is'thoroughly stirred and mixed 'by those blades. Although two bladesper setyas illustrated vin lFi'gxi are Veffective, four or more perset as in'liig` 1 may be used, if desired.

In uorder to improve-the stirringaction ofthe `stirring-devicesand thus toprovideifurther crys- `tal movement beyond what is 'provided for by the stirring blades 45 .and 46, I Yprovide a layer ofcoarse wiremesh 41, forexampleheavy wire with three-quarter inch to :one inch .or there- *abouts interstices. This .layer of wire mesh is laid .and secured against one edgeof the blades 45 4.5, preferably the leading edge "so that the .mesh vextends in approximately a radial direction Ytothe ends 'of the blades fromthe center of the stirring device. 'This '.mesh also serves to .drag 'the'massecuitefrom'the bottom uportion ofthe tank'tothetop .and'vice versa. This-novel feature is'valuable and Vimportant inmaintaining uniformity of treatment of all parts of .the massecuite.

`In order to drive the Astirring shaft '44 and hence the `rock shaft 25 with the'parts carried thereby, a motor :6c pconnected vwith suitable vreduction gearing 62 `may be provided. A "ilexible coupling 64 between the reduction gearing and the stirring shaft of the unit II causes the lstirring shaft of that unit to be driven bythe reduction gearing and motor 6I). On the stirring shaft of this unit I I are two sprocket wheels 65 and Sii-which rotate withit. Similar sprocket Wheels 61 'and `59 are mounted'uponthe stirring 'shafts of the 'units I and III, the sprocket wheel SI5-1 being connected to the wheel 55 by a chain 188 Yand the -sprocket 69 being connected with the sprocket 55 by a chain 63. Thusall ofthe stirring shafts of the three units are driven together and at the same speed bythe imotorand reduction gearing.

To distribute the entering massecuite as vit comes down the chute I E and to give it initial uniform movement into 'the first unit, distributing and mixing means are provided inthe form of rotating blades 34 Von a horizontal shaft 35 extending longitudinally through the end Wall I5 Abeing supported in bearing 36 abutting theoutside of wall I5.

To cause movement of the rmassecuitefrom the entrancetoward the discharge end of 4the crystalllzer, the whole apparatus is tilted so that the entrance end of the crystallizer is slightly above the discharge end. As the mass moves along the tank it is effectively and thoroughly mixed, stirred and cooled uniformly and finally reheated before discharge over the end plate I1. Preferably the end plate I1 is perforated so as to distribute the ow of massecuite as it discharges.

Many modifications within the scope of my invention will occur to those skilled in the art. Therefore I do not limit it to the specific form illustrated.

What is claimed is:

1. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let at one end and discharged at the other, a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged transversely of the tank substantially in vertical planes, means to move said devices to and fro in a direction parallel to the length of the tank to cause stirring of the mixture and heat transfer between said devices and mixture, and means causing movement of the mixture continuously along the tank from the inlet to the discharge end.

2. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let at one end and discharged at the other, a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged transversely of the tank substantially in vertical planes, means to move said devices to and fro in a direction parallel to the length of the tank to cause stirring of the mixture and heat transfer between said devices and mixture, means causing movement of the mixture continuously along the tank from the inlet to the discharge end and means causing stirring of the mixture between the planes of said heat transfer surfaces.

3. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let yat one end and discharged at the other, a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged tranversely of the tank substantially in vertical planes, means to move said devices to and fro in a direction parallel to the length of the tank to cause stirring of the mixture and heat transfer between said devices and mixture, means causing movement of the mixture continuously along the tank from the inlet to the discharge end, and stirring means causing movement of marginal portions of the mixture into said heat transfer devices.

4. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let at one end and discharged at the other, a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged transversely of the tank, means to move said devices to and fro in a direction parallel to the length of the tank to cause stirring of the mixture and heat transfer between said devices and mixture, means causing movement of the mixture continuously along the tank from the inlet to'the discharge end, and means at the inlet end to distribute the mixture and move it toward the rst heat transfer device.

5. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let at one end and discharged at the other,

a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged transversely of the tank, means to move said devices to and fro in a direction parallel to the length of the tank to cause stirring of the mixture and heat transfer between said devices and mixture, means causing movement of the mixture continuously along the tank from the inlet to the discharge end, and means associated with each heat transfer device to stir and mix the mixture within the zone of that device.

6. A crystallizer as claimed in claim 5 having means at the inlet end to distribute the mixture and move it toward the first heat transfer device.

'7. A crystallizer as claimed in claim 5 wherein the means to stir and mix is provided with blades which move the mixture inwardly from the side walls at both sides of the tank.

8. A crystallizer as claimed in claim 1 Wherein the heat transfer devices comprise tubes within which Water may circulate.

9. A crystallizer as claimed in claim 8 wherein the tubes each have a plurality of radial fins thereon.

10. A crystallizer as claimed in claim 9 wherein the fins on adjacent tubes are staggered.

11. A crystallizer as claimed in claim 1 wherein the heat transfer devices comprise a plurality of substantially parallel sets of sinusoidally arranged tubes within which water circulates.

12. A heat transfer device adapted for use as a unit of a continuous crystallizer for sugar bearing mixtures comprising a rockable shaft located transversely to the mixture fiow, supporting means mounted on said shaft and rockable therewith, a plurality of tubes for circulating water mounted on said supporting means and positioned transversely relative to the mixture flow and extending entirely across the path of mixture flow, and means to rock said shaft and tubes continuously to and fro parallel to the direction of the mixture flow.

13. A heat transfer device as claimed in claim 12 wherein the tubes comprise a plurality of substantially parallel sets of sinusoidally arranged tubes.

14. A heat transfer device as claimed in claim 13 wherein the sets of tubes are spaced apart, and between them is located stirring means.

15. A heat transfer device as claimed in claim 15 wherein the stirring means rotates and has blades turned to cause movement of the mixture axially inwardly from each end of the stirring means.

16. A heat transfer device as claimed in claim 12 wherein the supporting means comprise axially spaced parallel inverted U-plates having tubes mounted along the edges thereof.

17. A continuous crystallizer for sugar bearing mixtures comprising a tank into which the mixture is let at one end and discharged at the other, a plurality of individual heat transfer devices spaced along the tank each having heat transfer surfaces arranged transversely of the tank, means to move said devices to cause stirring of the mixture and heat transfer between said devices and mixture, means causing movement of the mixture continuously along the tank from the inlet to the discharge end, said tank being tilted downwardly toward the discharge end causing continuous flow of the mixture along the tank through said heat transfer devices.

18. A continuous crystallizer for sugar bearing '7 mixtures `comprisingfa tank intoV which the mixtureis let;at oneendand dischargedfatthe other, a A101111221111157 of invzlividual heat transfer devices Spacedfalong'the tankxeach having `a-fsetlof Lheat Atransfer surfaces ,arranged transversely of :the tank substantially in vertical planes, Vmeans :to passoooling fluid through said heat ltransfer dey.v eesto ;cause progressve :cooling of. said mixture as it passes each ,set of heat transfer :surfaces Yin moving. from the ,inlet toward :the discharge `end Vof :the Ltank, mea-ns to :move said devices to-and fro in a direction parallel to l.the ,length of ,the tank to vcause stirring of the-mixture, and Vmeans causing movement ,of l.the mixture continuously Number `8 .UNITED STATES :PAI'ENTS Name 'Date Ragot Aug. 18, 1903 -'Schultze Apr. 3,1906 Hansen Uuly .16, '1918 Kopke Mar. A4, 1930 Bonath Ju1y'l9, 1932 Ralston Nov. '7, 1933 Peck Aug. 28, '1934 Widmer Feb. 25, 1936 `Bonath 'May '30, 1939 Platte Nov. '25, 1941 FOREIGN RA'IENIS Country ,Date

along the Yiranlrfrmn thejnlet ,to the discharge v15 A-1mmn1oer end.

REFERENCES CITED le Of this :patenti

Claims (1)

1. A CONTINUOUS CRYSTALLIZER FOR SUGAR BEARING MIXTURES COMPRISING A TANK INTO WHICH THE MIXTURE IS LET AT ONE END AND DISCHARGED AT THE OTHER, A PLURALITY OF INDIVIDUAL HEAT TRANSFER DEVICES SPACED ALONG THE TANK EACH HAVING HEAT TRANSFER SURFACES ARRANGED TRANSVERSELY OF THE TANK SUBSTANTIALLY IN VERTICAL PLANES, MEANS TO MOVE SAID DEVICES TO AND FRO IN A DIRECTION PARALLEL TO THE LENGTH OF THE TANK TO CAUSE STIRRING OF THE MIXTURE AND HEAT TRANSFER BETWEEN SAID DEVICES AND MIXTURE, AND MEANS CAUSING MOVEMENT OF THE MIXTURE CONTINUOUSLY ALONG THE TANK FROM THE INLET TO THE DISCHARGE END.

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