EP0104277B1 - Preparation of seeding crystals for massecuite - Google Patents

Preparation of seeding crystals for massecuite Download PDF

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Publication number
EP0104277B1
EP0104277B1 EP82201191A EP82201191A EP0104277B1 EP 0104277 B1 EP0104277 B1 EP 0104277B1 EP 82201191 A EP82201191 A EP 82201191A EP 82201191 A EP82201191 A EP 82201191A EP 0104277 B1 EP0104277 B1 EP 0104277B1
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Prior art keywords
sugar
crystals
size
suspension
pressure
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EP82201191A
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German (de)
French (fr)
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EP0104277A1 (en
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Pieter Willem Van Der Poel
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CSM Suiker BV
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CSM Suiker BV
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Priority to EP82201191A priority Critical patent/EP0104277B1/en
Priority to DE8282201191T priority patent/DE3270132D1/en
Priority to AT82201191T priority patent/ATE18778T1/en
Priority to US06/531,926 priority patent/US4518436A/en
Priority to CA000437201A priority patent/CA1204438A/en
Priority to JP58174434A priority patent/JPS59175900A/en
Publication of EP0104277A1 publication Critical patent/EP0104277A1/en
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    • 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

Definitions

  • the invention relates to a process for the production of seed crystals for sugar infusion by adding a suspension containing a highly concentrated sugar solution to a ground sugar.
  • the vacuum is kept as constant as possible to eliminate temperature fluctuations.
  • inoculation is carried out in such a method in a crystallization vessel (cooking pan) with an internal heating element (steam box) and a total volume of 20-60 m 3 at a cooking fill level in which the steam box is flooded with supersaturated solution.
  • the mentioned parboiling level is about 30% of the final volume of the crystal mass in the pan.
  • the vaccination is carried out by adding the supersaturated solution of granulated sugar, powdered sugar, ground sugar or sugar suspension.
  • the seed crystals initiate nucleation, the formation of the final number of germs being determined by the length of time of the process and the supersaturation number of the solution in which further vaccination is carried out.
  • nucleation is stopped. This interruption occurs by reducing the supersaturation number. This reduction can be achieved by drawing in unsaturated sugar solution, drawing in water or raising the temperature (it is referred to as drawing in because the negative pressure prevailing when a valve is opened from a container under normal pressure draws a lot of sugar solution, water and the like into the crystallization vessel ).
  • the result obtained depends on the design of the cooking pan and the experience of the operating personnel. Sometimes irregular crystals with a large number of conglomerates with a very wide particle size distribution are obtained. The latter aspects are unfavorable for the quality of the end product because the removal of the mother liquor, which is usually carried out by centrifuging, is hindered thereby.
  • seed crystals of a much more regular distribution of the grain size can be obtained by adding a suspension at a parboiling level of 1.8-2.2% based on the brew content and a supersaturation number of 1.12 to 1.20 , which contains the sugar in a grain size of 5-20 pm, homogenizes the filling mass by means of an external circulation pump and crystallizes it, whereby liquid is evaporated and the temperature is reduced by adjusting the pressure, with the proviso that the oversaturation number is within the limit remains from 1.12 to 1.20.
  • the supersaturation number drops.
  • the latter is controlled by the pressure in the crystallization device in such a way that the temperature of the solution is regulated by means of water evaporation.
  • the water evaporation itself is regulated by means of the pressure across the liquid. It is important that, in contrast to normal practice, no heat is added at this stage of the process.
  • the volume used in this method of vaccination is less than the usual volume.
  • the temperature is reduced by 0.4-1.0 ° C per minute, in particular 0.6 ° C per minute. Particularly good crystals are obtained here.
  • the oversaturation number of the sugar solution is set precisely, for example to a value of 1.16.
  • the inoculation can be carried out here with a suspension of ground sugar in isopropanol, suitably with a concentration of 25-50% by volume of sugar, in particular 31-35% by volume of sugar, preferably 33% by volume of sugar.
  • the grain size of the ground sugar in this suspension is 5-20 ⁇ m, especially 8-12 p.m.
  • the crystallization is then carried out in such a way that the supersaturation is adjusted by cooling. This cooling is achieved by allowing liquid to evaporate, the evaporation being controlled by the pressure in the crystallization vessel.
  • the temperature of the cooking mass is expediently brought to 75-100 ° C, in particular 82-87 ° C and sometimes to 85 ° C.
  • the supersaturation number is determined based on the viscosity of the sugar solution; such a viscosity amounts to several hundreds of mPa.s.
  • the suspension is added and the cooking mass is cooled to 85 ° C to 75 ° C.
  • this cooling takes place by means of evaporation of the liquid.
  • evaporation expediently takes place within a period of 10 to 30, in particular 17 to 25 minutes.
  • the pressure is expediently 60 to 80 centibars.
  • the negative pressure is set by the pressure regulation in the top of the cooking pan, according to which the temperature is determined by water evaporation.
  • the regulation of the negative pressure is effected with the aid of a computer program, whereby the crystallization is optimal and secondary nucleation is prevented as far as possible.
  • the water vapor obtained is removed by drawing off in order to maintain the negative pressure.
  • the crystallization can be continued by applying heat with steam.
  • an inoculum material is obtained, the grain size of which is approximately 200 ⁇ m, because, as already mentioned, the grain size scatter is relatively small.
  • the construction of the device is such that an unsaturated solution is formed in the heat exchanger due to the heating and the circulation. By regulating the dwell time in the unsaturated zone and the degree of unsaturation, the secondary nucleation is eliminated by the fine crystals dissolving again.
  • the method according to the invention differs from the known one in that the entire process can be automated well, a small inoculation volume of, for example, 1 m 3 can be used, the solution is mixed with crystals up to 100 ⁇ m by means of a circulation pump, the number of crystals only by the amount of suspension is determined and the number of crystals can be better regulated, the supersaturation number is regulated by cooling instead of vaporization by steam until a crystal size of 100 ⁇ m is reached, the number of conglomerates is suppressed to a minimum, the small crystal nuclei are concentrated during the boiling Dissolve the undersaturated solution after the heat exchanger, whereby the undersaturation of the solution can be regulated by a) adjusting the temperature difference via the heat exchanger and b) by means of the point at which the mixed juice is drawn into either the circulation line or the pan.
  • the dwell time in the undersaturated zone is regulated by a circulation pump and is generally 5-25 seconds.
  • the horizontal mixing can be regulated by means of an agitator, but the vertical mixing is achieved by means of a circulation pump. If an agitator is used in the vessel, its design is such that the mixing takes place in layers.
  • a suitable device for carrying out the method according to the application is shown in the attached figure, where 1 is the container in which the seed crystals are produced, 2 is a stirrer of a type which enables layer-by-layer mixing, 3 is a line for evacuation to which an greatly reduced pressure can be applied and which is equipped with a valve 4, 5 are a pressure measuring element and 6 are a temperature measuring element. 4 and 5 as well as 6 are connected to an organ 7 which ensures that a predetermined program is carried out. Furthermore, the container is equipped with a filling height meter 8 and a viscosity meter 9. The bodies 8 and 9 are also connected to a member 10 for data processing, wherein the organ may be combined with the 1 0 organ. 7
  • a valved 12 supply (11) is further arranged which is connected to a water supply 13, an A syrup supply 14 and a mixed juice supply 1 5, which are provided with valves 16, 17 and 18, respectively, are themselves of are again connected to the control element 10.
  • the supply lines 13, 14 and 15 are also connected via a valve 19 to the discharge line 20 arranged at the bottom of the vessel.
  • the discharge line 20 is provided with a pump 21 for pumping off the liquid, a heat exchanger 22 which is expediently also a plate heat exchanger being arranged in this line.
  • This Plate heat exchanger is heated via a steam line 23 provided with a valve 24.
  • the valve 24 is controlled by the control element 25, which can be combined again with the elements 7 and 10.
  • the product passed through the heat exchanger 22 is returned to the container via line 26, in which a temperature measuring element 27 connected to the control element 25 is arranged.
  • This line is also equipped with a resistor 28 of 0.2 bar.
  • a discharge line 29 is connected to the vessel, which is provided with a valve 30 and which serves to discharge the suspension obtained from the vessel.
  • the improved crystal quality in the process according to the invention results in a reduction in the amount of mother liquor enclosed. An improvement in the quality of the end product is thereby achieved and the energy expenditure is reduced, less crystallization being required due to the improved crystal quality.
  • the reduced ash content and the smaller number of conglomerates indicate the improved crystal quality.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Organic Chemistry (AREA)
  • Saccharide Compounds (AREA)
  • Preparation Of Compounds By Using Micro-Organisms (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)

Abstract

Prodn. comprises mixing a sugar soln. having super-satn. no. 1.12-1.2 and vol. 1.8-2.2% of the end vol. with a suspension of ground sugar of grain-size 5-20 microns. The mixt. is homogenised with a rotary pump. Crystallisation takes place by adjusting the pressure in the crystallisation appts. so that liq. is evaporated and the temp. is lowered. The pressure redn. and/or the temp. is/are adjusted so that the super-satn. no. remains within the 1.12-1.2 limits. The inoculating crystals have uniform grain-size, e.g. of 200 microns. The process can be automated. The amt. of enclosed mother liquor in crystals is reduced, and end prod. has improved crystal quality, e.g. conglomerate amt. is reduced from 81.8%, for a standard process, to 13.7% and ash x 1000 from 11.8- to 7%, whereas average grain-size is increased from 0.58- to 0.64 mm. Energy consumption is lowered.

Description

Die Erfindung bezieht sich auf ein Verfahren zur Erzeugung von Impfkristallen für Zuckersude durch Versetzen einer hochkonzentrierten Zuckerlösung mit einer gemahlenen Zucker enthaltenden Suspension.The invention relates to a process for the production of seed crystals for sugar infusion by adding a suspension containing a highly concentrated sugar solution to a ground sugar.

Das bisher übliche Verfahren wird beispielsweise in R.A. McGinnis' Beet-Sugar Technology, Seiten 404 bis 408 beschrieben. Ein solches Verfahren besteht hauptsächlich aus den folgenden Massnahmen :

  • 1. ein Kristallisationsgefäss von 20 bis 60 m3 Rauminhalt wird mit Zuckerlösung gefüllt, dass das Heizelement bedeckt ist. Die Lösung wird bis Erreichung der zur Kristallbildung beziehungsweise zum Kristallwuchs erforderlichen Übersättigungszahl eingedickt. Während des Eindickens wird durch Zugabe von Zuckerlösung dafür Sorge getragen, dass das Heizelement immer bedeckt bleibt ;
  • 2. die übersättigte Lösung wird mit Pulverzucker, Kristallzucker oder einer Suspension von gemahlenem Zucker in Isopropanol geimpft ;
  • 3. die Übersättigung wird durch Wasserverdampfung aufrecht erhalten, wodurch der erwünschte Kristallwuchs erzielt wird. Währenddessen wird kontinuierlich frische Zuckerlösung zugegeben und bis zum Ausfüllen des Gefässes wird die Übersättigungszahl möglichst genau durch Wasserverdampfung und die Zugabe von frischer Zuckerlösung gesteuert. In dieser Weise bildet sich eine Masse aus etwa 60 Gew.% Kristallen in einer gesättigten Lösung ; und
  • 4. beim Erreichen der Füllhöhe des Gefässes wird eine stabile Übersättigungszahl aufrecht erhalten, wobei das Gemisch bei optimale Kristallausbeute kristallisiert.
The method which has been customary to date is described, for example, in RA McGinnis' Beet-Sugar Technology, pages 404 to 408. Such a procedure mainly consists of the following measures:
  • 1. a crystallization vessel of 20 to 60 m 3 volume is filled with sugar solution that the heating element is covered. The solution is thickened until the supersaturation number required for crystal formation or crystal growth is reached. During the thickening, the addition of sugar solution ensures that the heating element is always covered;
  • 2. the supersaturated solution is inoculated with powdered sugar, granulated sugar or a suspension of ground sugar in isopropanol;
  • 3. The supersaturation is maintained by water evaporation, whereby the desired crystal growth is achieved. In the meantime, fresh sugar solution is continuously added and until the vessel is filled, the supersaturation number is controlled as precisely as possible by water evaporation and the addition of fresh sugar solution. In this way, a mass of about 60% by weight of crystals is formed in a saturated solution; and
  • 4. When the fill level of the vessel is reached, a stable supersaturation number is maintained, the mixture crystallizing with optimum crystal yield.

Zur Förderung der Verdampfung wird bei einem derartigen Verfahren immer ein Unterdruck aufrecht erhalten. In der ersten Stufe des Verfahrens ist es schwer, Konglomeration der Kristalle vorzubeugen. Weiterhin bilden sich leicht feine sekundäre Kristalle, die eine Inhomogenität des Endproduktes verursachen.In order to promote evaporation, a vacuum is always maintained in such a process. In the first stage of the process, it is difficult to prevent conglomeration of the crystals. Furthermore, fine secondary crystals are easily formed, which cause inhomogeneity of the end product.

Zur Eliminierung von temperaturschwankungen wird der Unterdruck möglichst konstant gehalten.The vacuum is kept as constant as possible to eliminate temperature fluctuations.

Ein solches Verfahren wird ebenfalls kurz in « De Nederlandse Suikerindustrie" (1979), Seiten 44 und 45, beschrieben.Such a process is also briefly described in "De Nederlandse Suikerindustrie" (1979), pages 44 and 45.

In der Praxis wird das Impfen bei einem derartigen Verfahren in einem Kristallisationsgefäss (Kochpfanne) mit einem inneren Heizelement (Dampfkasten) und einem Gesamtrauminhalt von 20-60 m3 bei einer Kochfüllhohe durchgeführt, bei der der Dampfkasten von übersättigter Lösung überflutet ist. Das erwähnte Ankochfüllhöhe beträgt etwa 30 % des Endvolumens der Kristallmasse in der Kochpfanne. Das Impfen erfolgt dadurch, dass die übersättigte Lösung von Kristallzucker, Pulverzucker, gemahlenem Zucker oder Zuckersuspension versetzt wird. Die Impfkristallen lösen eine Keimbildung aus, wobei die Bildung der entgültigen Anzahl der Keime von der Zeitdauer des Prozesses und der Übersättigungszahl der Lösung, in der weiter geimpft wird, bestimmt wird.In practice, inoculation is carried out in such a method in a crystallization vessel (cooking pan) with an internal heating element (steam box) and a total volume of 20-60 m 3 at a cooking fill level in which the steam box is flooded with supersaturated solution. The mentioned parboiling level is about 30% of the final volume of the crystal mass in the pan. The vaccination is carried out by adding the supersaturated solution of granulated sugar, powdered sugar, ground sugar or sugar suspension. The seed crystals initiate nucleation, the formation of the final number of germs being determined by the length of time of the process and the supersaturation number of the solution in which further vaccination is carried out.

Wenn sich die erforderliche Anzahl von Kristallen gebildet hat, wird die Keimbildung unterbrochen. Diese Unterbrechung erfolgt durch Herabsetzung der Übersättigungszahl. Diese Herabsetzung kann durch Einziehen ungesättigter Zuckerlösung, Einziehen von Wasser oder Erhöhung der Temperatur erreicht werden (es wird von Einziehen geredet, weil durch den herrschenden Unterdruck beim Öffnen eines Ventils aus einem Behälter unter Normaldruck eine Menge von Zuckerlösung, Wasser und dergleichen ins Kristallisationsgefäss hineingezogen wird).When the required number of crystals have formed, nucleation is stopped. This interruption occurs by reducing the supersaturation number. This reduction can be achieved by drawing in unsaturated sugar solution, drawing in water or raising the temperature (it is referred to as drawing in because the negative pressure prevailing when a valve is opened from a container under normal pressure draws a lot of sugar solution, water and the like into the crystallization vessel ).

Bei diesem bekannten Verfahren wir das erhaltene Ergebnis durch die Bauart der Kochpfanne und die Erfahrung des Bedienungspersonals bedingt. Manchmal werden unregelmässige Kristalle mit einer grossen Anzahl von Konglomeraten bei sehr breiter Korngrössenverteilung erhalten. Die letzterwähnten Aspekte sind für die Qualität des Endproduktes ungünstig, weil die üblicherweise durch Schleudern durchgeführte Entfernung der Mutterlauge dadurch behindert wird.In this known method, the result obtained depends on the design of the cooking pan and the experience of the operating personnel. Sometimes irregular crystals with a large number of conglomerates with a very wide particle size distribution are obtained. The latter aspects are unfavorable for the quality of the end product because the removal of the mother liquor, which is usually carried out by centrifuging, is hindered thereby.

Ein weiterer Nachteil dieses bekannten Verfahrens ist, dass zur Abbrechung der Keimbildung meistens grosse Wassermengen eingezogen werden müssen, die später auch wieder verdampft werden müssen und folglich den Energieaufwand erhöhen.Another disadvantage of this known method is that large amounts of water usually have to be drawn in to stop the nucleation, which later have to be evaporated again and consequently increase the energy expenditure.

Es wurde jetzt gefunden, dass man Impfkristalle einer viel regelmässigeren Verteilung der Korngrösse dadurch enthalten kann, dass man bei einer Ankochfüllhöhe von 1,8-2,2% bezogen auf den Sudinhalt und einer Übersättigungszahl von 1,12 bis 1,20 eine Suspensions zugibt, die den Zucker in einer Körngrösse von 5-20 p.m enthält, die Füllmasse mittels einer aussenliegenden Umlaufpumpe homogenisiert und hierbei kristallisiert, wobei über die Einstellung des Drucks Flüssigkeit verdampft wird und die Temperatur herabgesetzt wird, mit der Massgabe, dass die Übersättungszahl innerhalb der Grenze von 1,12 bis 1,20 bleibt.It has now been found that seed crystals of a much more regular distribution of the grain size can be obtained by adding a suspension at a parboiling level of 1.8-2.2% based on the brew content and a supersaturation number of 1.12 to 1.20 , which contains the sugar in a grain size of 5-20 pm, homogenizes the filling mass by means of an external circulation pump and crystallizes it, whereby liquid is evaporated and the temperature is reduced by adjusting the pressure, with the proviso that the oversaturation number is within the limit remains from 1.12 to 1.20.

Der kristallisation zufolge sinkt'die Übersättingungszahl herab. Die Letzte wird jedoch über den Druck in der Kristallisationsvorrichtung gesteuert und zwar derart, dass die Temperatur der Lösung mittels Wasserverdampfung reguliert wird. Die Wasserverdampfung an sich wird mittels des Drucks über die Flüssigkeit reguliert. Wichtig ist dabei, dass im Gegensatz zu der normalen Praxis in dieser Stufe des Prozesses keine Wärme zugeführt wird. Das bei diesem Verfahren zum Impfen angewandte Volumen ist geringer als das übliche Volumen. Vorzugsweise wird eine Herabsetzung der Temperatur um 0,4-1,0 °C je Minute, insbesondere 0,6 °C je Minute angewandt. Hierbei werden besonders gute Kristalle erhalten.According to the crystallization, the supersaturation number drops. However, the latter is controlled by the pressure in the crystallization device in such a way that the temperature of the solution is regulated by means of water evaporation. The water evaporation itself is regulated by means of the pressure across the liquid. It is important that, in contrast to normal practice, no heat is added at this stage of the process. The volume used in this method of vaccination is less than the usual volume. Preferably, the temperature is reduced by 0.4-1.0 ° C per minute, in particular 0.6 ° C per minute. Particularly good crystals are obtained here.

Bei unseren Versuchen hat es sich herausgestellt, dass man in Kombination mit einem Kristallisationsgegfäss von 60 m3 Rauminhalt zweckmässig von einem Volumen von etwa 1 m3 ausgeht. Die Übersättingungszahl der Zuckerlösung wird genau und zwar beispielsweise auf einen Wert von 1,16 eingestellt. Das Impfen kann hierin mit einer Suspension von gemahlenem Zucker in Isopropanol, zweckmässig mit einer Konzentration von 25-50 Vol.% an Zucker, insbesondere 31-35 Vol.% an Zucker, vorzugsweise 33 Vol.% an Zucker durchgeführt werden.In our tests, it turned out that in combination with a crystallization vessel of 60 m 3 volume, it is expedient to assume a volume of about 1 m 3 . The oversaturation number of the sugar solution is set precisely, for example to a value of 1.16. The inoculation can be carried out here with a suspension of ground sugar in isopropanol, suitably with a concentration of 25-50% by volume of sugar, in particular 31-35% by volume of sugar, preferably 33% by volume of sugar.

Die Korngrösse des gemahlenen Zuckers in dieser Suspension ist 5-20 µm, insbesondere 8-12 p.m.The grain size of the ground sugar in this suspension is 5-20 µm, especially 8-12 p.m.

Die Kristallisation wird dann so geführt, dass die Übersättigung durch Kühlung eingestellt wird. Diese Kühlung wird dadurch erreicht, dass man Flüssigkeit verdampfen lässt, wobei die Verdampfung durch den Druck im Kristallisationsgefäss kontrolliert wird.The crystallization is then carried out in such a way that the supersaturation is adjusted by cooling. This cooling is achieved by allowing liquid to evaporate, the evaporation being controlled by the pressure in the crystallization vessel.

Bei diesem Verfahren wird die Temperatur der Kochmasse zweckmässig auf 75-100 °C, insbesondere auf 82-87 °C und manchmal auf 85 °C gebracht. Die Übersättigungszahl wird an Hand der Viskosität der Zuckerlösung bestimmt ; eine derartige Viskosität beläuft sich auf mehrere Hunderte mPa.s.In this process, the temperature of the cooking mass is expediently brought to 75-100 ° C, in particular 82-87 ° C and sometimes to 85 ° C. The supersaturation number is determined based on the viscosity of the sugar solution; such a viscosity amounts to several hundreds of mPa.s.

Wenn die erwünschte Übersättigungszahl der Zuckerlösung erreicht ist, wird, sie mit der Suspension versetzt und die Kochmasse auf 85 °C bis 75 °C abgekühlt. Wie bereits erwähnt, erfolgt diese Kühlung mittels Verdampfung der Flüssigkeit. Eine solche Verdampfung erfolgt zweckmässig innerhalb einer Zeitspanne von 10 bis 30, insbesondere von 17-25 Minuten. Der Druck ist dabei zweckmässig 60 bis 80 Centibar.When the desired supersaturation number of the sugar solution is reached, the suspension is added and the cooking mass is cooled to 85 ° C to 75 ° C. As already mentioned, this cooling takes place by means of evaporation of the liquid. Such evaporation expediently takes place within a period of 10 to 30, in particular 17 to 25 minutes. The pressure is expediently 60 to 80 centibars.

Der Unterdruck wird durch die Druckregulierung oben in der Kochpfanne eingestellt, demzufolge die Temperatur durch Wasserverdampfung bestimmt wird. Die Regulierung der Unterdrucks wird an Hand eines Computerprogramms bewirkt, wodurch die Kristallisation optimal ist und eine sekundäre Keimbildung möglichst unterbunden wird.The negative pressure is set by the pressure regulation in the top of the cooking pan, according to which the temperature is determined by water evaporation. The regulation of the negative pressure is effected with the aid of a computer program, whereby the crystallization is optimal and secondary nucleation is prevented as far as possible.

Der erhaltene Wasserdampf wird durch Abziehen zur Aufrechterhaltung des Unterdrucks abgeführt. Wenn die Kristalle eine Grösse von 100 p.m erreicht haben, kann die Kristallisation weiter durch Wärmezufuhr mittels Dampf fortgesetzt werden.The water vapor obtained is removed by drawing off in order to maintain the negative pressure. When the crystals have reached a size of 100 p.m, the crystallization can be continued by applying heat with steam.

Mit diesem Verfahren erhält man ein Impfmaterial, dessen Korngrösse etwa 200 µm ist, weil, wie bereits erwähnt, die Korngrössenstreuung relativ klein ist. Die Konstruktion der Vorrichtung ist derart, dass sich in dem Wärmeaustauscher durch die Aufwärmung und den Umlauf eine ungesättigte Lösung bildet. Durch die Regulierung der Verweilzeit in der ungesättigten Zone und des Ungesättigkeitgrades wird erreicht, dass die sekundäre Keimbildung aufgehoben wird, indem die Feinstkristalle sich wieder auflösen.With this method, an inoculum material is obtained, the grain size of which is approximately 200 μm, because, as already mentioned, the grain size scatter is relatively small. The construction of the device is such that an unsaturated solution is formed in the heat exchanger due to the heating and the circulation. By regulating the dwell time in the unsaturated zone and the degree of unsaturation, the secondary nucleation is eliminated by the fine crystals dissolving again.

Ebenfalls ergab sich in der Praxis, dass durch Impfung der üblichen Kochpfannen mit diesen erhaltenen Impfkristallen eine regelmässigere Streuung der Korngrösse im Endprodukt erhalten wird.It has also been found in practice that by inoculating the usual cooking pans with these seed crystals obtained, a more regular dispersion of the grain size in the end product is obtained.

Das erfindungsgemässe Verfahren unterscheidet sich darin vom bekannten, dass das Gesamtprozess gut automatisiert werden kann, ein geringes Impfvolumen von beispielsweise 1 m3 angewandt werden kann, die Lösung mit Kristallen bis 100 µm mittels einer Umlaufpumpe durchmischt wird, die Anzahl der Kristalle lediglich durch die Suspensionsmenge bestimmt wird und die Anzahl der Kristalle besser reguliert werden kann, die Übersättigungszahl durch Kühlung statt Verdampfung mittels Dampf bis Erreichung einer Kristallgrösse von 100 µm reguliert wird, die Anzahl an Konglomeraten auf ein Minimum zurück gedrängt wird, die kleinen Kristallkeime während der Hochkochung sich in der untersättigten Lösung nach dem Wärmeaustäuscher wieder auflösen, wobei die Untersättigung der Lösung mittels a) der Einstellung der Temperaturdifferenz über den Wärmeaustäuscher und b) mittels der Stelle des Einziehens des Mischsafts entweder in die Umlaufleitung oder in die Pfanne reguliert werden kann.The method according to the invention differs from the known one in that the entire process can be automated well, a small inoculation volume of, for example, 1 m 3 can be used, the solution is mixed with crystals up to 100 μm by means of a circulation pump, the number of crystals only by the amount of suspension is determined and the number of crystals can be better regulated, the supersaturation number is regulated by cooling instead of vaporization by steam until a crystal size of 100 µm is reached, the number of conglomerates is suppressed to a minimum, the small crystal nuclei are concentrated during the boiling Dissolve the undersaturated solution after the heat exchanger, whereby the undersaturation of the solution can be regulated by a) adjusting the temperature difference via the heat exchanger and b) by means of the point at which the mixed juice is drawn into either the circulation line or the pan.

Die Verweilzeit in der untersättigten Zone wird durch eine Umlaufpumpe reguliert und ist im allgemeinen 5-25 Sekunden.The dwell time in the undersaturated zone is regulated by a circulation pump and is generally 5-25 seconds.

Beim anmeldungsgemässen Verfahren kann die Horizontaldurchmischung mittels eines Rührwerks reguliert werden, jedoch die Vertikaldurchmischung wird mittels einer Umlaufpumpe erreicht. Falls im Gefäss ein Rührwerk angewandt wird, ist dessen Bauart so, dass das Durchmischen schichtweise stattfindet.In the method according to the application, the horizontal mixing can be regulated by means of an agitator, but the vertical mixing is achieved by means of a circulation pump. If an agitator is used in the vessel, its design is such that the mixing takes place in layers.

Eine geeignete Vorrichtung zur Durchführung des anmeldungsgemässen Verfahren ist in der beiliegenden Abbildung wiedergegeben, wobei 1 der Behälter ist, worin die Impfkristalle erzeugt werden, 2 ein Rührer einer Bauart ist, der eine Schichtweise Durchmischung ermöglicht, 3 eine Leitung zum Evakuieren ist, an die ein stark herabgesetzter Druck angelegt werden kann und die mit einem Ventil 4 ausgestattet ist, 5 ein Druckmessorgan und 6 ein Temperaturmessorgan sind. 4 und 5 wie auch 6 sind mit einem Organ 7 verbunden, das dafür Sorge trägt, dass ein vorbestimmtes Programm durchgeführt wird. Weiterhin ist der Behälter mit einem Füllhöhenmesser 8 und einem Viskositätsmesser 9 ausgestattet. Die Organe 8 und 9 sind ebenfalls mit einem Organ 10 zur Datenverarbeitung verbunden, wobei das Organ 10 mit dem Organ 7 kombiniert sein kann.A suitable device for carrying out the method according to the application is shown in the attached figure, where 1 is the container in which the seed crystals are produced, 2 is a stirrer of a type which enables layer-by-layer mixing, 3 is a line for evacuation to which an greatly reduced pressure can be applied and which is equipped with a valve 4, 5 are a pressure measuring element and 6 are a temperature measuring element. 4 and 5 as well as 6 are connected to an organ 7 which ensures that a predetermined program is carried out. Furthermore, the container is equipped with a filling height meter 8 and a viscosity meter 9. The bodies 8 and 9 are also connected to a member 10 for data processing, wherein the organ may be combined with the 1 0 organ. 7

Unterhalb der normalen Flüssigkeitshöhe ist weiterhin eine mit einem Ventil 12 versehene Zufuhr (11) angeordnet, die mit einer Wasserzufuhr 13, einer A-Sirupzufuhr 14 und einer Mischsaftzufuhr 15 verbunden ist, welche mit Ventilen 16, 17 beziehungsweise 18 versehen sind, die ihrerseites wieder mit dem Regelorgan 10 verbunden sind. Die Zufuhrleitungen 13, 14 und 15 sind ebenfalls über ein Ventil 19 mit der am Boden des Gefässes angeordneten Abfuhrleitung 20 verbunden. Die Abfuhrieitung 20 ist zum Abpumpen der Flüssigkeit mit einer Pumpe 21 versehen, wobei weiterhin in dieser Leitung ein Wärmeaustauscher 22 angeordnet ist, der zweckmässig ein Plattenwärmeaustauscher ist. Dieser Plattenwärmeaustauscher wird über eine mit einem Ventil 24 versehene Dampfleitung 23 beheizt. Das Ventil 24 wird vom Regelorgan 25 gesteuert, das wieder mit den Organen 7 und 10 kombiniert worden kann. Das durch den Wärmeaustäuscher 22 geführte Produkt wird über Leitung 26, worin ein mit dem Regelorgan 25 verbundenes Temperaturmessorgan 27 angeordnet ist, zum Behälter zurückgeführt. Diese Leitung ist weiterhin mit einem Widerstand 28 von 0,2 bar ausgestattet.Below the normal liquid level, a valved 12 supply (11) is further arranged which is connected to a water supply 13, an A syrup supply 14 and a mixed juice supply 1 5, which are provided with valves 16, 17 and 18, respectively, are themselves of are again connected to the control element 10. The supply lines 13, 14 and 15 are also connected via a valve 19 to the discharge line 20 arranged at the bottom of the vessel. The discharge line 20 is provided with a pump 21 for pumping off the liquid, a heat exchanger 22 which is expediently also a plate heat exchanger being arranged in this line. This Plate heat exchanger is heated via a steam line 23 provided with a valve 24. The valve 24 is controlled by the control element 25, which can be combined again with the elements 7 and 10. The product passed through the heat exchanger 22 is returned to the container via line 26, in which a temperature measuring element 27 connected to the control element 25 is arranged. This line is also equipped with a resistor 28 of 0.2 bar.

Schliesslich ist mit dem Gefäss eine Abfuhrleitung 29 verbunden, die mit einem Ventil 30 versehen ist und die zur Abfuhr der erhaltenen Suspension aus dem Gefäss dient.Finally, a discharge line 29 is connected to the vessel, which is provided with a valve 30 and which serves to discharge the suspension obtained from the vessel.

Die verbesserte Kristallqualität beim erfindungsgemässen Verfahren bringt eine Herabsetzung der eingeschlossenen Mutterlaugemenge mit sich. Es werden dadurch eine Verbesserung der Qualität des Endproduktes erreicht und der Energieaufwand herabgesetzt, wobei aufgrund der verbesserten Kristallqualität weniger Kristallisation erforderlich ist.The improved crystal quality in the process according to the invention results in a reduction in the amount of mother liquor enclosed. An improvement in the quality of the end product is thereby achieved and the energy expenditure is reduced, less crystallization being required due to the improved crystal quality.

Die folgende Tabelle vergleicht die Ergebnisse von Impfkristallen aus einer üblichen Impfkristallerzeugung in einer üblichen Kristallisationsvorrichtung mit denjenigen, die nach dem erfindungsgemässen Verfahren erhalten werden.

Figure imgb0001
The following table compares the results of seed crystals from conventional seed crystal production in a conventional crystallization device with those obtained by the process according to the invention.
Figure imgb0001

Der herabgesetzte Aschegehalt sowie die kleinere Konglomeratezahl weisen auf die verbesserte Kristallqualität hin.The reduced ash content and the smaller number of conglomerates indicate the improved crystal quality.

Claims (2)

1. A process for the preparation of seed crystals for sugar decoctions (massecuites) by mixing a highly concentrated sugar solution with a suspension containing ground sugar, characterised in that, at a filling level at the start of boiling of from 1.8 to 2.2% in relation to the decoction content and at a supersaturation value of from 1.12 to 1.20, a suspension is added which contains the sugar in a particle size of from 5 to 20 p.m, the batch is homogenised by means of an external circulation pump and then crystallised, where upon by a adjusting the pressure liquid is vaporised and the temperature is reduced, provided that the supersaturation value remains within the limit of 1.12 to 1.20.
2. A process according to Claim 1, characterised in that, after the seed crystals have attained a size of 100 by cooling, to bring about further vaporisation and to dissolve the secondary crystals, vapour is fed to a heat exchanger disposed outside the crystallisation apparatus.
EP82201191A 1982-09-23 1982-09-23 Preparation of seeding crystals for massecuite Expired EP0104277B1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
EP82201191A EP0104277B1 (en) 1982-09-23 1982-09-23 Preparation of seeding crystals for massecuite
DE8282201191T DE3270132D1 (en) 1982-09-23 1982-09-23 Preparation of seeding crystals for massecuite
AT82201191T ATE18778T1 (en) 1982-09-23 1982-09-23 PROCESS FOR GENERATION OF SEED CRYSTALS FOR SUGAR BROTH.
US06/531,926 US4518436A (en) 1982-09-23 1983-09-13 Process for the production of graft crystals for use in seeding sugar boiling brines
CA000437201A CA1204438A (en) 1982-09-23 1983-09-21 Process for the production of crystalline sugar, particularly seed crystals for subsequent use in sugar boiling solutions
JP58174434A JPS59175900A (en) 1982-09-23 1983-09-22 Production of graft crystal for boiled surcrose suspension

Applications Claiming Priority (1)

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EP82201191A EP0104277B1 (en) 1982-09-23 1982-09-23 Preparation of seeding crystals for massecuite

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EP0104277B1 true EP0104277B1 (en) 1986-03-26

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FI77693C (en) * 1987-06-03 1989-04-10 Suomen Sokeri Oy Procedure for crystallization of fructose.
DE4028071A1 (en) * 1990-09-05 1992-03-12 Krupp Buckau Maschinenbau Gmbh METHOD FOR GRAINING IN THE CRYSTALIZATION OF A SUGAR FILLED JUICE
US6663780B2 (en) 1993-01-26 2003-12-16 Danisco Finland Oy Method for the fractionation of molasses
FI96225C (en) 1993-01-26 1996-05-27 Cultor Oy Process for fractionation of molasses
US5795398A (en) 1994-09-30 1998-08-18 Cultor Ltd. Fractionation method of sucrose-containing solutions
US6224776B1 (en) * 1996-05-24 2001-05-01 Cultor Corporation Method for fractionating a solution
DE19913587A1 (en) * 1999-03-24 2000-09-28 Nordzucker Ag Process for sucrose crystallization using a sugar dust suspension as the initial crystallizate
FI20010977A (en) * 2001-05-09 2002-11-10 Danisco Sweeteners Oy Chromatographic separation method
US9309576B2 (en) * 2013-03-13 2016-04-12 Rockwell Automation Technologies, Inc. Sugar crystallization control system and method

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FR1368118A (en) * 1963-01-11 1964-07-31 Improvements in sugar crystallization
BE709700A (en) * 1968-01-22 1968-05-30
US3503803A (en) * 1968-03-22 1970-03-31 Whiting Corp Continuous production of crystalline sucrose
US3617382A (en) * 1968-07-17 1971-11-02 Christos B Natsis Mixing apparatus as used in mass and heat transfer processes
FR1597729A (en) * 1968-12-06 1970-06-29
IL35793A (en) * 1969-12-12 1973-10-25 Stamicarbon Continuous process for crystallization
US4004886A (en) * 1969-12-12 1977-01-25 Stamicarbon B.V. Two stage continuous process and apparatus for crystallization
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JPS5821390Y2 (en) * 1978-10-27 1983-05-06 泉工医科工業株式会社 liquid storage bag
JPS5933836Y2 (en) * 1979-09-20 1984-09-20 丸山工業株式会社 Refrigerant charge valve
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JPS5829999U (en) * 1981-08-19 1983-02-26 株式会社島津製作所 liquid delivery container

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ATE18778T1 (en) 1986-04-15
EP0104277A1 (en) 1984-04-04
JPS6257320B2 (en) 1987-11-30
JPS59175900A (en) 1984-10-04
DE3270132D1 (en) 1986-04-30
US4518436A (en) 1985-05-21
CA1204438A (en) 1986-05-13

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