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EP-4239084-B1 - A CONTINUOUS VACUUM CRYSTALLIZER AND A METHOD OF CRYSTALLIZING SUGAR

EP4239084B1EP 4239084 B1EP4239084 B1EP 4239084B1EP-4239084-B1

Inventors

  • Ghurair, Jamal AL
  • Ferkh, Riad EL
  • Chennakrishnan, Lakshmama Gounder

Dates

Publication Date
20260506
Application Date
20220328

Claims (16)

  1. A continuous vacuum crystallizer (100) for crystallization of sugar, the continuous vacuum crystallizer (100) comprising: a cylindrical housing (202) having at least one inlet passage (605) adapted to receive a flow of steam and at least one outlet passage (606) adapted to receive a flow of vapor; a plurality of vacuum chambers (302) coaxially stacked in the cylindrical housing (202) over each other, the plurality of vacuum chambers (302) adapted to be in fluid communication with each other and with each of the at least one inlet passage (605) and the at least one outlet passage (606), wherein one of the plurality of vacuum chambers (302) is adapted to receive mother liquor which is cascaded down through each of the plurality of vacuum chambers (302); a plurality of calandrias (602) disposed within the plurality of vacuum chambers (302) and adapted to heat the mother liquor, wherein each of the plurality of calandrias (602) is adapted to receive the steam through a plurality of openings located around each of the plurality of calandrias (602), wherein the plurality of openings is in fluid communication with the at least one inlet passage (605); and a plurality of agitators (614) disposed within the plurality of vacuum chambers (302), wherein the plurality of agitators (614) is coupled to at least one shaft adapted to be driven by at least one driving member disposed at one of a top portion of the cylindrical housing (202) and a bottom portion of the cylindrical housing (202), wherein the at least one shaft comprises a first shaft and a second shaft, wherein the first shaft is adapted to drive a first set of agitators (614-1) from among the plurality of agitators (614), and wherein the second shaft is adapted to drive a second set of agitators (614-2) from among the plurality of agitators (614), wherein the flow of vapor from each of the plurality of vacuum chambers (302) is collected in one header and then been re-compressed to generate the flow of steam which is fed to each of the plurality of vacuum chambers (302) through the plurality of openings.
  2. The continuous vacuum crystallizer (100) according to claim 1, wherein the plurality of vacuum chambers (302) includes at least one receiver chamber (302-1), a plurality of seed chambers disposed below the at least one receiver chamber (302-1), and a plurality of boiling chambers (302-3) disposed below the plurality of seed chambers, each of the plurality of boiling chambers (302-3) is adapted to convert the mother liquor into massecuite which is continuously cascaded down to a succeeding boiling chamber from among the plurality of boiling chambers (302-3).
  3. The continuous vacuum crystallizer (100) according to claim 2, wherein the at least one receiver chamber (302-1), the plurality of seed chambers, and the plurality of boiling chambers (302-3) are operated at a first vapor pressure, a second vapor pressure, and a third vapor pressure, respectively, a value of the second vapor pressure is higher than a value of the third vapor pressure.
  4. The continuous vacuum crystallizer (100) according to claim 2, wherein each of the at least one inlet passage (605) and the at least one outlet passage (606) are defined between an inner wall of the cylindrical housing (202) and an outer wall of the cylindrical housing (202), the at least one inlet passage (605) comprising: a plurality of inlet passages defined circumferentially between the inner wall and the outer wall of the cylindrical housing (202) and vertically extending from one of a pair of seed chambers to one of the plurality of boiling chambers (302-3) disposed at the bottom portion of the cylindrical housing (202), wherein each of the plurality of inlet passages is adapted to equally distribute the flow of steam to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3) through the plurality of openings at a same time.
  5. The continuous vacuum crystallizer (100) according to any of claims 3 and 4, wherein the at least one outlet passage (606) comprises: a first set of outlet passages (606-1) positioned circumferentially around the pair of seed chambers and adapted to circulate a flow of vapor at the second vapor pressure between each of the pair of seed chambers; and a second set of outlet passages (606-2) positioned circumferentially around the plurality of boiling chambers (302-3) and adapted to circulate a flow of vapor at the third vapor pressure between each of the plurality of boiling chambers (302-3).
  6. The continuous vacuum crystallizer (100) according to claim 5, further comprising: a plurality of vapor outlets adapted to connect the one of the pair of seed chambers and one of the plurality of boiling chambers (302-3) disposed below the corresponding seed chamber, wherein the plurality of vapor outlets is adapted to supply vapor from the one of the pair of seed chambers to the one of the plurality of boiling chambers (302-3) to maintain lower vapor pressure in the plurality of boiling chambers (302-3) through at least one control valve.
  7. The continuous vacuum crystallizer (100) according to any of claims 4 and 5, wherein the first set of outlet passages (606-1) and the second set of outlet passages (606-2) are adapted to be in fluid communication with a vapor circulation network comprising: at least one Mechanical Vapor Re-compressor, MVR, adapted to receive the flow of vapor from the pair of seed chambers and the plurality of boiling chambers (302-3), and adapted to generate a flow of steam by re-compressing the flow of vapor, wherein a conduit in fluid communication with the at least one MVR and adapted to supply the flow of steam from the at least one MVR to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3), the conduit is circumferentially positioned on the outer wall of the cylindrical housing (202) and is adapted to be in fluid communication with each of the plurality of inlet passages to supply the flow of steam received from the at least one MVR.
  8. The continuous vacuum crystallizer (100) according to any of the preceding claims, further comprising: a first overflow conduit in fluid communication with the at least one receiver chamber (302-1); a second overflow conduit in fluid communication with each of the pair of seed chambers; and a third overflow conduit in fluid communication with each of the plurality of boiling chambers (302-3), wherein each of the first overflow conduit, the second overflow conduit, and the third overflow conduit is adapted to collect excess amount of mother liquor from each of the plurality of vacuum chambers (302), the at least one receiver chamber (302-1) is adapted to receive the collected mother liquor.
  9. The continuous vacuum crystallizer (100) according to any of the preceding claims, wherein the first shaft is adapted to be drivably coupled to a first driving member disposed at the top portion of the cylindrical housing (202), wherein the first set of agitators (614-1) from among the plurality of agitators (614) is disposed within the at least one receiver chamber (302-1), the pair of seed chambers, and at least one of the plurality of boiling chambers (302-3); and the second shaft is adapted to be drivably coupled to a second driving member disposed at the bottom portion of the cylindrical housing (202), wherein the second set of agitators (614-2) from among the plurality of agitators (614) is disposed within at least one of the plurality of boiling chambers (302-3).
  10. A method (900) of crystallizing sugar in a continuous vacuum crystallizer (100) according to any of claims 1-9, the method (900) comprising: receiving feed solution in at least one receiver chamber (302-1) positioned above a pair of seed chambers and a plurality of boiling chambers (302-3), wherein the at least one receiver chamber (302-1), the pair of seed chambers, and the plurality of boiling chambers (302-3) are coaxially stacked in a cylindrical housing (202) over each other; dropping the feed solution into the pair of seed chambers, wherein the feed solution is saturated by adding slurry while dropping the feed solution in one of the pair of seed chambers from the at least one receiver chamber (302-1); supplying mother liquor from the pair of seed chambers to one of the plurality of boiling chambers (302-3) positioned below the pair of seed chambers, wherein the mother liquor is converted into massecuite, wherein a plurality of agitators (614) are disposed within each of the plurality of boiling chambers (302-3), wherein the plurality of agitators (614) is coupled to at least one shaft adapted to be driven by at least one driving member disposed at one of a top portion of the cylindrical housing (202) and a bottom portion of the cylindrical housing (202), wherein the at least one shaft comprises a first shaft and a second shaft, wherein the first shaft is adapted to drive a first set of agitators (614-1) from among the plurality of agitators (614), and wherein the second shaft is adapted to drive a second set of agitators (614-2) from among the plurality of agitators (614); and cascading the massecuite from one of the plurality of boiling chambers (302-3) to succeeding boiling chamber, wherein a concentration of the massecuite is increased in the succeeding boiling chamber compared to a concentration of the massecuite received from preceding boiling chamber from among the plurality of boiling chambers (302-3), wherein a flow of steam is supplied to each of the plurality of boiling chambers (302-3), the flow of steam is converted in a flow of vapor which is collected in one header and then been re-compressed to generate the flow of steam, the re-compressed flow of steam is fed to each of the plurality of boiling chambers (302-3) and the pair of seed chambers.
  11. The method (900) according to claim 10, further comprising equally distributing the flow of steam to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3) through a plurality of openings at a same time, wherein the plurality of openings is located around each of a plurality of calandrias (602) disposed within the pair of seed chambers and the plurality of boiling chambers (302-3).
  12. The method (900) according to claim 10, further comprising: circulating a flow of vapor at a second vapor pressure between each of the pair of seed chambers through a first set of outlet passages (606-1), wherein the first set of outlet passages (606-1) is positioned circumferentially around the pair of seed chambers; and circulating a flow of vapor at a third vapor pressure between each of the plurality of boiling chambers (302-3) through a second set of outlet passages (606-2), wherein the second set of outlet passages (606-2) is positioned circumferentially around the plurality of boiling chambers (302-3).
  13. The method (900) according to any of claims 10 and 12, further comprising: supplying vapor, through a plurality of vapor outlets, from the one of the pair of seed chambers to the one of the plurality of boiling chambers (302-3) to maintain lower vapor pressure in the plurality of boiling chambers (302-3), wherein the plurality of vapor outlets is adapted to connect the one of the pair of seed chambers and the one of the plurality of boiling chambers (302-3) disposed below the corresponding seed chamber.
  14. The method (900) according to claim 10, further comprising: receiving, by at least one Mechanical Vapor Re-compressor, MVR, the flow of vapor from the pair of seed chambers and the plurality of boiling chambers (302-3); re-compressing the flow of vapor by the at least one MVR to generate a flow of steam; and supplying the flow of steam from the at least one MVR to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3).
  15. The method (900) according to claim 10, wherein the feed solution having sugar content in a range of 75 °Brix to 78 °Brix is received in the at least one receiver chamber (302-1) at a temperature of 100 - 106 ° C.
  16. The method (900) according to claim 10, further comprising collecting the massecuite from one of the plurality of boiling chambers (302-3) disposed at a bottom portion of the cylindrical housing (202), wherein: a temperature of the massecuite is in a range of 52 ° C to 69 ° C based on a pressure of a flow of steam supplied to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3); and a sugar content of the massecuite is in a range of 89.3 °Brix to 90.97 °Brix based on the pressure of the flow of steam supplied to each of the pair of seed chambers and each of the plurality of boiling chambers (302-3).

Description

FIELD OF THE INVENTION The present disclosure relates to sugar crystallization and in particular relates to, a continuous vacuum crystallizer and a method of crystallizing sugar in the continuous vacuum crystallizer. BACKGROUND Currently, sugar is one of the largest industries in the world, and crystallization is of central importance there. Crystallization of the sugar is a technological step to recover the sucrose dissolved in a thick juice. Generally, various crystallization devices, such as a vertical continuous vacuum pan, are employed for performing the crystallization process to obtain the sugar content from a liquor. For instance, such crystallization devices include multiple chambers operating independently to perform the crystallization process in order to extract the sugar content from the liquor. Further, in such crystallization devices, the crystallization process is performed under higher pressure and a higher temperature within multiple chambers. However, this results in the formation of the sugar crystals at a higher temperature which further leads to an increase in the color of the sugar mother liquor. Although, such a change in color of the sugar crystals may not be suitable and therefore, require further processing of the sugar crystals in order to obtain the suitable color of the sugar crystal. However, further processing of the sugar crystals results in a substantial increase in the overall production cost of the sugar crystals. Further, in the crystallization devices, each of the multiple chambers is provided with an independent actuation unit having various sub-components, such as separate chambers, pumps, vacuum, and steam valves. However, such an arrangement substantially increases the overall maintenance cost of the crystallization devices. In addition, such existing crystallization devices have multi risk of vacuum leaks & liquor leaks at each chamber. WO2007/113849 A1 describes a vertical continuous vacuum pan apparatus consisting of eight chambers and a storage or buffer tank at the top. Further, BR9105163A describes an apparatus for continuous evaporation crystallization of a mixture of acyclic crystals and a saturated acyclic syrup. SUMMARY This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention. The invention is set out in the appended set of claims. To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: Figure 1 illustrates an elevated view of a continuous vacuum crystallizer for crystallization of sugar, according to an embodiment of the present disclosure;Figure 2 illustrates an isometric view of the continuous vacuum crystallizer for crystallization of sugar, according to an embodiment of the present disclosure;Figure 3 illustrates a sectional view of the continuous vacuum crystallizer, according to an embodiment of the present disclosure;Figure 4 illustrates a partial sectional view of the continuous vacuum crystallizer depicting the receiver chamber and the plurality of seed chamber, according to an embodiment of the present disclosure;Figure 5 illustrates a partial sectional view of the continuous vacuum crystallizer 100 depicting the plurality of boiling chambers, according to an embodiment of the present disclosure;Figure 6 illustrates a top sectional view of the continuous vacuum crystallizer depicting at least one vacuum chamber for crystallization of sugar, according to an embodiment of the present disclosure;Figure 7 illustrates an isometric sectional view of the continuous vacuum crystallizer depicting at least one vacuum chamber, according to an embodiment of the present disclosure;Figure 8 illustrates a schematic view of an environment depicting re-circulation of steam to the continuous vacuum crystallizer, according to an embodiment of the present disclosure; andFigure 9 illustrates a flowchart depicting a method of crystallizing sugar in the continuous vacuum crystallizer, according to an embodiment of the present disclosure. Further, skilled artisans will appre