Classifications

• • C—CHEMISTRY; METALLURGY
  • C13—SUGAR INDUSTRY
  • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
  • C13B30/00—Crystallisation; Crystallising apparatus; Separating crystals from mother liquors ; Evaporating or boiling sugar juice
  • C13B30/02—Crystallisation; Crystallising apparatus
  • C13B30/022—Continuous processes, apparatus therefor
• • C—CHEMISTRY; METALLURGY
  • C13—SUGAR INDUSTRY
  • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
  • C13B30/00—Crystallisation; Crystallising apparatus; Separating crystals from mother liquors ; Evaporating or boiling sugar juice
  • C13B30/02—Crystallisation; Crystallising apparatus
  • C13B30/022—Continuous processes, apparatus therefor
  • C13B30/023—Continuous processes, apparatus therefor having rotatable means for agitation or transportation

Definitions

• the present invention relates to a method and device for continuous crystallization of a composition containing sugar, as a last crystallization jet.
• the purpose of crystallization in a sugar refinery is to extract in crystallized form, with as high a yield as possible, the sugar (sucrose) dissolved in a syrup and thus to separate it from the soluble impurities (non-sugars) collected in the molasses.
• This process is based on related physical parameters such as solubility, viscosity, temperature, internal agitation without forgetting the criteria of purity (percentage of sugar on dry matter) and possible chemical degradation under certain conditions.
• jets according to the different diagrams in 4, 3 or 2 jets.
• the first jet which has the highest purity, is the sugar extraction jet enabling the quality objective of the desired sugar to be satisfied.
• the last jet, or low product jet, which has the lowest purity is the molasses extraction jet aiming for the highest possible yield of crystallized sugar called exhaustion of molasses.
• the large amount of non-sugar in this jet slows the rate of crystallization.
• a rapid crystallization device in a continuous or discontinuous cooking appliance the crystals are formed by seeding and magnification at a fixed temperature (from 75 ° C. to 85 ° C.) by maintaining by evaporation a given supersaturation of the syrup food; the crystallized mass (or cooked mass) formed passes through a buffer casting mixer; in this phase, it is necessary to adjust the purity of the baked mass formed to an optimal value required to obtain good exhaustion of the final molasses: this desirable purity is between 75 and 80: it results from a compromise between the speed of crystallization as a function of the non-sugar content and of the compactness of the baked mass linked to the crystal content;
• This process represents, compared to a re-entry of molasses in cooking appliances or mixers, the advantage of avoiding the recycling of non-sugars and dyes detrimental to the quality of brown sugar due to the long residence times; it consists in removing during the mixing a proportion of cooked mass, extracting the crystals by centrifugation and recycling the centrifugation syrup (pseudo-molasses) in the rest of the cooked mass; the sample can be taken from the casting mixer or from the first third of the mixers at a percentage calculated so as to reduce the crystal population; it is compulsory to recycle the pseudo-molasses of the demulsed pre-turbination and devoid of micro crystals: this involves reheating equipment and a demulsification device (possibly under vacuum); 1.4 the cooked mass warmed at the end of mixing is wrung on centrifuges to give the final molasses and the final brown sugar; this brown sugar and that from the pre-turbination are recycled in the form of a recast in the jet preced
• French patent n ° 1368118 describes a crystallization process consisting in taking a part of the cooked mass at the outlet of a cooking appliance, in making it undergo a turbine operation and in reinjecting the mother water thus obtained, at the level of one of the crystallization stages.
• This process requires additional turbination on the one hand, leads to a loss of energy not used for crystallization, on the other hand.
• the crystallization surface of the remaining cooked mass is reduced, which is directed towards the mixer.
• the mother water reinjected spontaneously crystallizes by cooling, giving parasitic grains of small size which pass through the sieve of the centrifuges, which reduces all the more the extraction in crystals of the whole of the jet.
• French Patent No. 2,534,595 relates to a process for crystallizing a sugar syrup which consists in subjecting the syrup to continuous or discontinuous baking so as to obtain a baked mass and to subject the baked mass to continuous mixing under vacuum and then to a turbination making it possible to separate the crystals from the mother liquor called "lean sewer" from the crystallization jet considered, characterized in that the lean sewer from the crystallization jet considered is partly recycled during the kneading steps under vacuum. The poor non-recycled sewer is directed to the next stream to be crystallized.
• This process as described is inapplicable to the treatment of the last crystallization jet, because the continuous mixing under vacuum, at this stage, is insufficient to obtain sufficient exhaustion of the mother liquor.
• this mother liquor is the final jet in the final molasses, the impurity rate of which prevents any crystallization in a following jet.
• One of the aspects of the invention is to propose a crystallization process which makes it possible to obtain the same results of depletion of the mother liquor of the last crystallization jet as the conventional processes but in a treatment time significantly reduced by half.
• One of the other aspects of the invention is also to provide a device making it possible to reduce the degradation of the sugar, therefore the losses in sucrose, and to improve the quality of the white sugar obtained on the first jet.
• One of the other aspects of the invention is to provide a crystallization process making it possible to suppress a crystallization jet in general 4-jet or 3-jet processes.
• One of the other aspects of the invention is to provide a simplified crystallization process allowing a gain in investment in material and in energy need.
• the subject of the invention is a process for crystallizing sugar from a composition containing sugar and a level of non-sugar such that the purity of the composition is from approximately 80 to approximately 84, characterized in that it comprises continuous mixing under vacuum of the above composition using a continuous vacuum mixer in order to crystallize the sugar contained in the composition. Purity is defined as the percentage of sucrose in the dry matter.
• the composition, at the outlet of the continuous vacuum mixer is separated into two fractions, in a ratio of about 0.66 to about 1.22, and advantageously in substantially equal mass, one of the fractions being treated so as to separate the sugar from the mother water, the mother water also being designated by pseudo-molasses, which is recycled in the continuous mixer under vacuum.
• the method of the invention comprises the following steps: - at the outlet of the continuous mixer under vacuum, the composition is separated into a first and a second fraction, in a ratio: second fraction on the first fraction by weight, from about 0.66 to about 1.22, in particular using pumps,
• the first fraction of the baked mass is treated by means allowing the crystallization to continue, for example by cooling, advantageously in vertical mixers,
• the second fraction is subjected to a pre-turbination step giving on the one hand pre-turbo sugar and on the other hand pseudo-molasses, which is recycled in the continuous mixer under vacuum.
• the continuous kneading under vacuum is carried out under a vacuum comprised of approximately 900 ⁇ 10 2 Pa to approximately 920 ⁇ 10 2 Pa, corresponding to a temperature of the composition of approximately 65 ° C to approximately 60 ° C, for a period of approximately 2:30 to approximately 4 hours, advantageously for a period of approximately 3 hours.
• the crystallization process comprises several successive crystallizations, also designated by "jets", in particular 2, 3 or 4 jets, and is characterized in that the above composition is a baked mass of the last so-called candy jet “base products” containing water, dissolved sugar, non-sugars and sucrose crystals, which composition advantageously comes from a so-called “sewer” sugar syrup from the jet preceding the above-mentioned last jet, which sugar syrup is previously subjected to a continuous or discontinuous cooking operation.
• non-sugar denotes dry matter other than sucrose.
• dissolved sugar is meant sucrose dissolved in mother water of the composition.
• continuous cooking operation is meant, for example, a device allowing continuous magnification of the sucrose crystals of a composition previously containing small crystals. This device called continuous cooking works continuously without periodic emptying.
• the average opening of the crystals before the baking operation is 0.2 mm to 0.3 mm and at the end of the baking operation, it is 0.5 mm to 0, 6 mm.
• discontinuous cooking operation is meant, for example, a device allowing formation of crystals by sowing and then a magnification of these crystals.
• This device called discontinuous baking works discontinuously with emptying as soon as the height of the cooked mass in the appliance has reached a maximum value (that is to say as soon as the appliance is full).
• the composition, in particular the cooked mass at the inlet of the continuous mixing under vacuum has the following characteristics:
• composition, in particular the cooked mass, at the end of the continuous mixing under vacuum has the following characteristics: - percentage by weight of dry matter: 94 to 93.5
• sucrose crystal content 30 to 35% by weight of the cooked mass; - purity of the mother liquor: 63 to 65; the increase in% by weight of the crystals between the inlet and the outlet of the vacuum mixer being from approximately 15% to approximately 25 °%.
• the increase in weight of the crystals results essentially from the magnification of the crystals entering the continuous mixer under vacuum; there is indeed very little or no formation of new crystals in the continuous vacuum mixer.
• the temperature of the composition in particular of the cooked mass on its entry into the continuous mixer under vacuum, is from about 75 ° C to about 85 ° C, and at its exit has a temperature d '' about 60 ° C to about 65 ° C.
• the pseudo-molasses defined above is advantageously reheated to a temperature of about 86 ° C to about 88 ° C, then this aforementioned pseudo molasses is then reintroduced into the continuous mixer under vacuum, in order to regulate the percentage by weight of crystals of the cooked mass treated in the continuous vacuum mixing, this percentage being advantageously from approximately 30% to approximately 35% by weight of the cooked mass (in the continuous vacuum mixer ).
• the two pumps which drive the two fractions of the composition, in particular of the cooked mass, regulate the height of the cooked mass in the continuous vacuum mixer, the percentage of crystals in the cooked mass being advantageously regulated by the speed ratio of the two pumps.
• the ratio of the flow rates of the two pumps is approximately 0.66 to approximately 1.22, in particular approximately 1.
• the composition in particular in the cooked mass, at the exit of the vertical mixers, one separates on the one hand the molasses, in particular of purity of approximately 58 to approximately 62, and on the other hand the brown sugar, of coloring of approximately 3000 ICUMSA , in particular by turbination, which brown sugar is subjected to a pasting, in particular using a sewer, advantageously having the following characteristics:
• the sugar coming from the pasting is subjected to a refining step to give on the one hand a refined sugar of coloring of approximately 1000 to 1200 ICUMSA, and on the other hand a sewer of refining of a percentage by weight of dry matter of approximately 80 and of a purity of approximately 81 to approximately 82.
• the pre-turbo sugar defined above exhibiting in particular a coloring of approximately 1000 to approximately
• the refined sugar defined above is added or not with pre-turbo sugar defined above, is advantageously remelted using first-throw sugar syrup having the following characteristics: - percentage by weight dry matter: 71;
• the refining sewer defined above is recycled into the sewer before the continuous or discontinuous baking defined above.
• the invention relates to a device for crystallizing a final crystallization jet, comprising:
• cylindrical mixers (6) comprising:
• means for input (6a) of the baked mass connected to the output of the casting mixer (4) and means for output (6b, 6c) of the baked mass, one of the means for output of the baked mass ( 6b) being connected to pre-turbining means (11), which pre-turbining means give on the one hand a pseudo-molasses, and on the other hand turbinated sugar, .
• input means (6d) of the pseudo-molasses connecting the output means (11a) of the pre-turbination means (11) to recycle the pseudo-molasses previously heated by heating means (14) in the mixer (s) (s) cylindrical (6).
• the device for crystallizing a final crystallization jet of the invention comprises:
• cylindrical mixers (6) comprising:
• pre-turbining means means for input (6a) of the baked mass connected to the output of the casting mixer (4) and means for output (6b, 6c) of the baked mass, one of the means for output of the baked mass ( 6b) being connected to pre-turbining means (11), which pre-turbining means give on the one hand a pseudo-molasses, and on the other hand turbinated sugar,.
• the device for crystallizing a final crystallization jet comprises:
• cylindrical mixers (6) comprising:
• means for input (6a) of the baked mass connected to the output of the casting mixer (4) and means for output (6b, 6c) of the baked mass, one of the means for output of the baked mass ( 6b) being connected to pre-turbining means (11), which pre-turbining means give on the one hand a pseudo-molasses, and on the other hand turbinated sugar, .
• input means (6d) of the pseudo-molasses connecting the output means (11a) of the pre-turbination means (11) to recycle the pseudo-molasses previously heated by heating means (14) in the mixer (s) (s) cylindrical (s) (6);
• the characteristics of the invention are essentially at the level of phases and devices 1-1, 1-2 and 1-3 described above as follows from the example below.
• Figure 1 schematically shows a device for implementing the invention.
• the rapid crystallization process in a continuous or discontinuous cooking appliance is associated with the continuous vacuum mixing process (MCSV) applied to low purities 80-84 which can be carried out in 1 or 2 successive stages.
• MCSV continuous vacuum mixing process
• the cooked mass 3a leaving the casting mixer if the cooking appliance is a discontinuous cooking or leaving directly from the cooking appliance if it is a continuous cooking, is extracted by a pump and is directed to a mixing device continuous vacuum 6, the characteristics of which are as follows:. length: 3.2 m. diameter: 1.4 m . total volume: 5 m 3 . engine power: 3 kW. agitator rotation speed: 2 rpm.
• the characteristics of the cooked mass 3a entering the continuous vacuum mixer are as follows:
• . terracotta temperature 80 ° C.
• the residence time of the cooked mass in the continuous vacuum mixer is approximately 3 hours.
• the essential difference between the continuous vacuum mixer and the other types of crystallizers is that the cooling is done by auto evaporation and not by exchange with a fluid.
• the characteristics of the cooked mass leaving the mixer 6 are as follows:
• the fraction 9 is subjected to a pre-turbination in a turbine 11 to separate the pre-turbined sugar 12 from the pseudo-molasses 13 consisting of mother liquor, dissolved sugar and impurities.
• the characteristics of the pseudo-molasses after reheating through a heater 14, are as follows:. percentage by weight of dry matter: 87.88. flow rate: 0.35 T / h. purity: 64.78
• the pre-turbinated mass flow rate is approximately 0.53 T / h (item 19), or 41% of the outgoing mass mass.
• the value of the vacuum in the continuous vacuum mixer at 18 is 900 x 10 2 Pa.
• the crystallization rate is 5 times higher than in the traditional process with cooling of 15 ° C in 3 hours and recycling of pseudo-molasses of 30-35% MC input.
• Part of the cooked mass 10 is directed to the vertical mixers
• the cooked MCSV output is then treated in a conventional kneading, continuous vertical type, as described above, of reduced duration (20 to 25 hours) to allow the same exhaustion of the final molasses to be achieved as the conventional scheme (purity: 58 to 62).
• the residence time in vertical mixers is 20 to 25 hours.
• the temperature of the cooked mass at the outlet of the vertical mixers is from 45 ° C to 55 ° C (item 21).
• the cooked mass undergoes turbination 22, to give molasses 23 of purity from 58 to 62, and brown sugar 24, of coloration 3000 ICUMSA, which brown sugar is subjected to a pasting in a pasting
• the pre-turbo sugar 12 can be partly mixed with brown sugar before the pasting operation. After the pasting, the sugar is subjected to a refining 27, using water 28, to give a refined sugar 29 of coloring 1000 to 1200 ICUMSA and a refining sewer 30, of percentage by weight of dry matter of 80 and purity of 81 to 84, which is recycled in the drain pan 20.
• the pre-turbo sugar 12 can be partly added to the refined sugar 29.
• the refined sugar 29 is then subjected to an overhaul 31, of percentage by weight of dry matter from 74 to 75 and of purity 93.5 to 94.5, using first-jet syrup 32 (percentage by weight of matter dry: 71; purity: 93 to 94), then the syrup 33 from the redesign is sent to the crystallization of the first jet.
• the refining device as described above can be used to achieve the production of high purity white sugar in the first stream.
• the crystallization process according to the invention can be qualified as "cold crystallization”. It considerably reduces any phenomenon of recoloration of baked mass linked to the residence time by thermal and chemical degradation. This clearly appears in the results concerning the coloring of the brown sugar obtained.
• the amount of water used is reduced by about 50% compared to the amount of water used in the processes of the prior art.

Landscapes

• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biochemistry (AREA)
• Organic Chemistry (AREA)
• Saccharide Compounds (AREA)
• Confectionery (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Coloring Foods And Improving Nutritive Qualities (AREA)
• Jellies, Jams, And Syrups (AREA)
• Medicines Containing Plant Substances (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9481068

Family Applications (1)

Country Status (12)

Families Citing this family (1)

Family Cites Families (5)

• 1995
  • 1995-07-18 FR FR9508645A patent/FR2736932B1/fr not_active Expired - Fee Related
• 1996
  • 1996-07-16 MA MA24312A patent/MA23937A1/fr unknown
  • 1996-07-17 ES ES96925804T patent/ES2164906T3/es not_active Expired - Lifetime
  • 1996-07-17 HU HU97023049702304A patent/HUP9702304A3/hu unknown
  • 1996-07-17 DK DK96925804T patent/DK0784705T3/da active
  • 1996-07-17 CZ CZ1997752A patent/CZ287127B6/cs not_active IP Right Cessation
  • 1996-07-17 AT AT96925804T patent/ATE207968T1/de not_active IP Right Cessation
  • 1996-07-17 EP EP96925804A patent/EP0784705B1/de not_active Expired - Lifetime
  • 1996-07-17 DE DE69616494T patent/DE69616494T2/de not_active Expired - Fee Related
  • 1996-07-17 AU AU66187/96A patent/AU6618796A/en not_active Abandoned
  • 1996-07-17 WO PCT/FR1996/001117 patent/WO1997004135A1/fr active IP Right Grant
  • 1996-07-17 PL PL96319181A patent/PL183201B1/pl not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events