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WO2007065279A1 - Process and unit for continuous drying of rice - Google Patents

Process and unit for continuous drying of rice Download PDF

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Publication number
WO2007065279A1
WO2007065279A1 PCT/CH2006/000645 CH2006000645W WO2007065279A1 WO 2007065279 A1 WO2007065279 A1 WO 2007065279A1 CH 2006000645 W CH2006000645 W CH 2006000645W WO 2007065279 A1 WO2007065279 A1 WO 2007065279A1
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WO
WIPO (PCT)
Prior art keywords
rice
drying
temperature
fluidized bed
paddy
Prior art date
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Ceased
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PCT/CH2006/000645
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German (de)
French (fr)
Inventor
Enrique Niño PEREZ
Leo Eisenring
Urs Keller
Eliana Zamprogna
Christian Ettel
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Buehler AG
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Buehler AG
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Publication date
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Priority to CN200680046231XA priority Critical patent/CN101326420B/en
Publication of WO2007065279A1 publication Critical patent/WO2007065279A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed

Definitions

  • the invention relates to a process for the continuous drying of rice, in particular paddy rice, and a device for the continuous drying of rice.
  • Freshly harvested rice has an initial moisture content of more than 20%, which must be reduced to a storage moisture content of approx. 14%.
  • the roughly pre-cleaned rice (paddy) is first stored in dryer pre-cells, before being dried by mechanical dryers. Drying takes place predominantly in several passages in roof dryers to which warm air of 50-60 ° C. is applied (for example in accordance with WO 98/45656). There is a waiting time of up to 12 hours between the individual passages. As with tower dryers, a limited degree of drying of up to 2% is possible. A standoff of at least 2 hours is required between the individual passages in order to achieve temperature compensation between the grain and the shell. The necessary mechanical transport processes increase the breakage.
  • Static drying in silos or halls requires large areas because the layer thickness of the rice to be dried is limited (approx. 80 to 100 cm). The drying runs unevenly from the inside out due to the arrangement of the ventilation devices and it is difficult to control because there is no really even air distribution. The time expenditure is also high.
  • DE-A-2938620 shows a continuous dryer with a cylindrical drying zone which has perforated plates. This is followed by a similarly designed cooling zone.
  • the DE-A- 41 19787 shows a conditioning device for bulk plant materials with a closed, tunnel-like conditioning station, through which a transport path leads, on which the bulk material is guided. The bulk material is exposed to a gaseous heat transfer medium.
  • Such conveyors can have porous surfaces through which hot or cold gases can flow in order to heat or cool grain and to reduce the moisture content (WO 01/02786).
  • DE-A-19806951 discloses a device for puffing granular material, in which the material is heated batchwise in a fluidized bed chamber.
  • EP-A-1099380 discloses a process for the production of heat-treated cereals, the heat treatment being carried out by means of a gas stream in an annular fluidized bed. The gas flow has different speed components.
  • raw rice with about 18% moisture content with hot air at about 140 0 C is heated for about 30 minutes. Drying can take place in a drum dryer or in a fluidized bed, with the starch being thermally influenced. The dried paddy rice is then directly peeled or peeled and cooled if the peeling is necessary to achieve an easily cookable, unpolished rice.
  • Dried and pre-cleaned rice can then be stored like any other grain until it is ready for processing.
  • the invention is based on the object to at least partially eliminate the disadvantages of the prior art and to develop a method for the continuous drying of rice, in particular paddy.
  • the problem is solved with the features of claim 1 and advantageous embodiments are disclosed in the subclaims.
  • the invention is based on the assumption that rice (paddy) could behave similarly to a polymer under certain humidity and temperature conditions, since, depending on the constellation of these conditions, a glassy or rubbery state is possible.
  • paddy At a low temperature (up to room temperature) and an initial humidity greater than 20%, paddy is glassy, but changes to a rubbery state when the temperature rises. This condition can now be maintained while maintaining the temperature and dehumidifying at the same time. When it cools down, the paddy returns to a glassy state.
  • This knowledge can now be used to dry paddy with high initial moisture (e.g. 22-24%) in a continuous process and still avoid grain breakage.
  • the Paddy is to heated to a temperature above 50 ° to 55 0 C,% in stages to about 13 moisture content and subsequently dried at ambient temperature but at least cooled to below 40 ° C.
  • the heating and drying is preferably carried out in a fluidized bed.
  • the internal pressure in the grain of rice increases due to the evaporation of water.
  • pressure equalization between grain and. Moisture can escape from the surrounding area.
  • the treatment in the fluidized bed is carried out in several stages, in particular in four stages.
  • annealing takes place in a fluidized bed before any further drying (called post-drying).
  • post-drying After a final stage, a combined drying / cooling to 13% moisture content or. a temperature of approx. 35 ° C.
  • the rice breakage is significantly reduced by specifically coordinating the drying and cooling of the paddy.
  • the disclosed procedure can also be used to adapt to the initial conditions of rice and process air.
  • Another object is to provide a device for the continuous drying of rice, particularly suitable for carrying out the method according to the invention.
  • Separators and readout machines known per se for pre-cleaning and fluidized bed apparatus for drying are used here.
  • the invention is described below in two exemplary embodiments with reference to a drawing.
  • the drawing shows a simplified diagram in the single figure.
  • the raw rice delivered with a moisture content of approx. 22% -24% passes from a depot 1 into a drum screen 2, where very coarse impurities are removed.
  • This is followed by further pre-cleaning in a separator / classifier 3 in order to separate stones, sand but also light impurities such as paper, straw or loose shells.
  • the design of the pre-cleaning depends on the degree of contamination of the raw rice delivered. It is advantageous to largely separate loose impurities and additives from the paddy rice before further treatment.
  • a further Depot 4 of the rice enters into a first fluidized bed apparatus 5, in which a rice layering of flows of hot air down, heated to at least about 5O 0 C and is dried to about 3-4% moisture .
  • the rice then passes directly into a second fluidized bed apparatus 6, in which the temperature is raised and drying takes place by a further 3-4% moisture, so that a moisture content of approximately 18% is achieved.
  • the paddy subsequently arrives in a stand-off container 7, which is not explicitly shown, where a first tempering is carried out.
  • the paddy then arrives in a third fluidized bed apparatus (not shown) for subsequent drying and then in another stand-off container for a second tempering.
  • This second tempering is followed by a further drying step in a fourth fluidized bed apparatus, which is followed by a third tempering.
  • the Paddy passes into a further silo where the Paddy in the reverse air current to about 35 0 C and cooled simultaneously to again about 1% is dried to a final moisture content of about 12.5% -13% is achieved becomes.
  • the evaporative cooling of the water in the paddy
  • Level and / or temperature probes are arranged in the latter silo cell in order to achieve certain product heights with a defined dwell time.
  • the paddy is heated in each drying stage (pre- and post-drying) so that the paddy is always in a rubber-elastic state.
  • the rice can also be cooled more quickly (with or without pre-cooling in the second fluidized bed apparatus 6) in a countercurrent cooler, for example within about 15 minutes.
  • the Unterhalfder plant is also less complex and due to the short drying times, the paddy rice can be stored faster or more rice can be purchased at harvest time.
  • very moist raw rice (for example with an initial moisture content of approx. 37%) is dried in a roof dryer with a fluid bed in several stages.
  • the first stage may already take place with superheated steam of about 12O 0 C for 3 hours.
  • the humidity is reduced to approx. 20-22%.
  • the steam supply is gradually reduced and the air or steam temperature is also gradually reduced to 50 ° C.
  • the result is a moisture content of approx. 13%.
  • the rice is inside a. cooled to ambient temperature within half an hour, with no more steam being supplied. A moisture content of approx. 12.5% can be achieved.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
  • Storage Of Harvested Produce (AREA)

Abstract

The invention relates to a process and a device for continuous drying of rice, in particular paddy rice having a relatively high initial moisture content. The purpose is to reduce significantly the treatment time and grain breakage. This is achieved according to the invention by the fact that precleaning of the paddy is followed by stepwise drying in a fluidized bed in combination with stepwise heating, and the paddy is only cooled subsequently.

Description

Verfahren und Einrichtung zur kontinuierlichen Trocknung von Reis  Process and device for continuous drying of rice

Die Erfindung betrifft ein Verfahren zur kontinuierlichen Trocknung von Reis, insbesondere von Paddyreis sowie eine Einrichtung zur kontinuierlichen Trocknung von Reis. The invention relates to a process for the continuous drying of rice, in particular paddy rice, and a device for the continuous drying of rice.

Erntefrischer Reis weist eine Anfangsfeuchte von mehr als 20% auf, die auf eine Lagerfeuchte von ca. 14% verringert werden muss. Der grob vorgereinigte Reis (Paddy) wird zunächst in Trockner-Vorzellen eingelagert, um anschliessend durch mechanische Trockner getrocknet zu werden. Das Trocknen erfolgt vorwiegend in mehreren Passagen in mit Warmluft von 50-60°C beaufschlagten Dächer-Trocknern (zum Beispiel ge- mäss der WO 98/45656). Zwischen den einzelnen Passagen liegt eine Abstehzeit von bis zu 12 Stunden. Wie auch bei Turmtrocknern ist nur ein begrenzter Trocknungsgrad von bis zu 2% möglich. Zwischen den einzelnen Passagen ist ein Abstehen von mindestens 2 Stunden gefordert, um einen Temperaturausgleich zwischen Korn und Schale zu erreichen. Die notwendigen, mechanischen Transportvorgänge erhöhen die Bruchbildung. Freshly harvested rice has an initial moisture content of more than 20%, which must be reduced to a storage moisture content of approx. 14%. The roughly pre-cleaned rice (paddy) is first stored in dryer pre-cells, before being dried by mechanical dryers. Drying takes place predominantly in several passages in roof dryers to which warm air of 50-60 ° C. is applied (for example in accordance with WO 98/45656). There is a waiting time of up to 12 hours between the individual passages. As with tower dryers, a limited degree of drying of up to 2% is possible. A standoff of at least 2 hours is required between the individual passages in order to achieve temperature compensation between the grain and the shell. The necessary mechanical transport processes increase the breakage.

Bei einer statischen Trocknung in Silos bzw. Hallen sind grosse Flächen erforderlich, da die Schichtdicke des zu trocknenden Reises begrenzt ist (ca. 80 bis 100 cm). Die Trocknung verläuft ungleichmässig von innen nach aussen auf Grund der Anordnung der Belüftungseinrichtungen und sie ist schlecht kontrollierbar, da keine wirklich gleichmässige Luftverteilung gegeben ist. Der Zeitaufwand ist ebenfalls hoch. Static drying in silos or halls requires large areas because the layer thickness of the rice to be dried is limited (approx. 80 to 100 cm). The drying runs unevenly from the inside out due to the arrangement of the ventilation devices and it is difficult to control because there is no really even air distribution. The time expenditure is also high.

Gemäss DE-A-2926256 wird bei einem Trocknungsverfahren für Getreide Frischluft erwärmt und über das Getreide geführt, wobei die Frischluft vorgängig noch gekühlt wird, um deren Feuchtegehalt zu verringern. Eine ähnliche Lösung ist in der DE-A- 2947759 offenbart. According to DE-A-2926256, in a drying process for cereals, fresh air is heated and passed over the cereals, the fresh air being cooled beforehand in order to reduce its moisture content. A similar solution is disclosed in DE-A-2947759.

Die DE-A-2938620 zeigt einen Durchlauftrockner mit einer zylindrigen Trocknungszone, die Lochbleche aufweist. Dieser folgt eine gleichartig gestaltete Kühlzone. Die DE-A- 41 19787 zeigt eine Konditioniereinrichtung für pflanzliche Schüttgüter mit einer geschlossenen, tunnelartigen Konditionierstation, durch die eine Transportbahn führt, auf der das Schüttgut geführt wird. Hierbei wird das Schüttgut einem gasförmigen Wärmeträger ausgesetzt. DE-A-2938620 shows a continuous dryer with a cylindrical drying zone which has perforated plates. This is followed by a similarly designed cooling zone. The DE-A- 41 19787 shows a conditioning device for bulk plant materials with a closed, tunnel-like conditioning station, through which a transport path leads, on which the bulk material is guided. The bulk material is exposed to a gaseous heat transfer medium.

Solche Förderer können poröse Oberflächen aufweisen, die von warmen oder kalten Gasen durchströmt werden können, um Getreide zu erwärmen oder zu kühlen und den Feuchtegehalt zu reduzieren (WO 01/02786). Such conveyors can have porous surfaces through which hot or cold gases can flow in order to heat or cool grain and to reduce the moisture content (WO 01/02786).

Die DE-A-19806951 offenbart eine Vorrichtung zum Puffen von körnigem Gut, bei der das Gut in einer Wirbelbettkammer batchweise erwärmt wird. Die E P-A- 1099380 offenbart ein Verfahren zur Herstellung von wärmebehandeltem Getreide, wobei die Wärmebehandlung mittels einem Gasstrom in einem ringförmigen Wirbelbett erfolgt. Der Gasstrom weist verschiedene Geschwindigkeitskomponenten auf. DE-A-19806951 discloses a device for puffing granular material, in which the material is heated batchwise in a fluidized bed chamber. EP-A-1099380 discloses a process for the production of heat-treated cereals, the heat treatment being carried out by means of a gas stream in an annular fluidized bed. The gas flow has different speed components.

Nach der JP-A-58056650 wird roher Reis mit ca. 18% Feuchtegehalt mit Warmluft von ca. 1400C ca. 30 Minuten lang erwärmt. Die Trocknung kann in einem Trommeltrockner oder auch im Wirbelbett erfolgen, wobei die Stärke thermisch beeinflusst wird. Der getrocknete Rohreis wird dann direkt geschält oder geschält und gekühlt, falls das schälen zur Erzielung eines leicht kochbaren, unpolierten Reises erforderlich ist. According to JP-A-58056650 raw rice with about 18% moisture content with hot air at about 140 0 C is heated for about 30 minutes. Drying can take place in a drum dryer or in a fluidized bed, with the starch being thermally influenced. The dried paddy rice is then directly peeled or peeled and cooled if the peeling is necessary to achieve an easily cookable, unpolished rice.

Getrockneter und vorgereinigter Reis kann dann wie jedes andere Getreide auch bis zur Verarbeitung gelagert werden. Dried and pre-cleaned rice can then be stored like any other grain until it is ready for processing.

Der Erfindung liegt nun die Aufgabe zugrunde, die aufgezeigten Nachteile des Standes der Technik wenigstens teilweise zu beseitigen und ein Verfahren zur kontinuierlichen Trocknung von Reis, insbesondere von Paddy zu entwickeln. Die Lösung der Aufgabe erfolgt mit den Merkmalen des Anspruchs 1 und vorteilhafte Ausgestaltungen sind in den Unteransprüchen offenbart. The invention is based on the object to at least partially eliminate the disadvantages of the prior art and to develop a method for the continuous drying of rice, in particular paddy. The problem is solved with the features of claim 1 and advantageous embodiments are disclosed in the subclaims.

Der Erfindung liegt die Annahme zugrunde, dass sich Reis (Paddy) unter bestimmten Feucht- und Temperaturbedingungen ähnlich einem Polymer verhalten könnte, da je nach Konstellation dieser Bedingungen ein glasiger oder ein gummiartiger Zustand möglich ist. Bei tiefer Temperatur (etwa bis zur Raumtemperatur) und einer Anfangsfeuchte grösser 20% ist Paddy glasig, geht aber bei Temperaturerhöhung in einen gummiartigen Zustand über. Dieser Zustand kann nun bei halten der Temperatur und gleichzeitiger Entfeuchtung erhalten werden. Bei Abkühlung erreicht der Paddy wieder einen glasigen Zustand. Diese Erkenntnis kann nun verwendet werden, um Paddy mit hoher Ausgangsfeuchte (z. B. 22-24%) in einem kontinuierlichen Verfahren zu trocknen und dennoch Kornbruch zu vermeiden. Der Paddy wird dazu auf eine Temperatur oberhalb 50° bis 550C erwärmt, in Stufen auf ca. 13% Feuchtegehalt getrocknet und an- schliessend auf Umgebungstemperatur, jedoch mindestens auf unter 40°C gekühlt. The invention is based on the assumption that rice (paddy) could behave similarly to a polymer under certain humidity and temperature conditions, since, depending on the constellation of these conditions, a glassy or rubbery state is possible. At a low temperature (up to room temperature) and an initial humidity greater than 20%, paddy is glassy, but changes to a rubbery state when the temperature rises. This condition can now be maintained while maintaining the temperature and dehumidifying at the same time. When it cools down, the paddy returns to a glassy state. This knowledge can now be used to dry paddy with high initial moisture (e.g. 22-24%) in a continuous process and still avoid grain breakage. The Paddy is to heated to a temperature above 50 ° to 55 0 C,% in stages to about 13 moisture content and subsequently dried at ambient temperature but at least cooled to below 40 ° C.

Das erwärmen und trocknen erfolgt bevorzugt in einer Wirbelschicht. In der warmen Wirbelschicht erhöht sich der innere Druck im Reiskorn durch Verdampfung von Wasser. Durch Druckausgleich zwischen Korn und. Umgebung kann die Feuchtigkeit aus dem Korn austreten. The heating and drying is preferably carried out in a fluidized bed. In the warm fluidized bed, the internal pressure in the grain of rice increases due to the evaporation of water. By pressure equalization between grain and. Moisture can escape from the surrounding area.

Die Behandlung in der Wirbelschicht erfolgt mehrstufig, insbesondere vierstufig. Nach der zweiten Stufe einer Vortrocknung erfolgt vor jeder weiteren Trocknung (Nachtrocknung genannt) in einer Wirbelschicht ein Tempern. Nach einer letzten Stufe erfolgt im Silo ein kombiniertes Trocknen/Kühlen auf 13% Feuchtegehalt resp. eine Temperatur von ca. 35°C. The treatment in the fluidized bed is carried out in several stages, in particular in four stages. After the second stage of predrying, annealing takes place in a fluidized bed before any further drying (called post-drying). After a final stage, a combined drying / cooling to 13% moisture content or. a temperature of approx. 35 ° C.

Durch gezielte Abstimmung von Trocknung und Kühlung des Paddy wird der Reisbruch deutlich reduziert. Ebenso ist mit der offenbarten Verfahrensweise eine Anpassung an die Ausgangsbedingungen von Reis und Prozessluft herstellbar. The rice breakage is significantly reduced by specifically coordinating the drying and cooling of the paddy. The disclosed procedure can also be used to adapt to the initial conditions of rice and process air.

Unter Zufuhr von Heissdampf ist bei hohem Feuchtegehalt von Paddy auch ein Trocknungsbeginn bei höherer Temperatur (bis ca. 1200C) möglich. With the addition of hot steam and a high moisture content of paddy, it is also possible to start drying at a higher temperature (up to approx. 120 0 C).

Eine weitere Aufgabe besteht in der Schaffung einer Einrichtung zur kontinuierlichen Trocknung von Reis, insbesondere geeignet zur Ausführung des erfindungsgemässen Verfahrens. Zur Anwendung kommen hierbei an sich bekannte Separatoren und Auslesemaschinen für die Vorreinigung und Wirbelschichtapparate für die Trocknung. Die Erfindung wird nachfolgend in zwei Ausführungsbeispielen an Hand einer Zeichnung näher beschrieben. Die Zeichnung zeigt in der einzigen Figur ein vereinfachtes Diagramm. Another object is to provide a device for the continuous drying of rice, particularly suitable for carrying out the method according to the invention. Separators and readout machines known per se for pre-cleaning and fluidized bed apparatus for drying are used here. The invention is described below in two exemplary embodiments with reference to a drawing. The drawing shows a simplified diagram in the single figure.

Der angelieferte Rohreis mit einer Feuchte von ca. 22%-24% gelangt aus einem Depot 1 in ein Trommelsieb 2, wo sehr grobe Verunreinigungen entfernt werden. Dem folgt eine weitere Vorreinigung in einem Separator/Klassifizierer 3, um Steine, Sand aber auch leichte Verunreinigungen wie Papier, Stroh oder lose Schalen abzutrennen. Die Ausgestaltung der Vorreinigung ist abhängig vom Verunreinigungsgrad des angelieferten Rohreises. Es ist vorteilhaft, lose Verunreinigungen und Beimengungen vor der weiteren Behandlung weitgehend vom Rohreis zu trennen. The raw rice delivered with a moisture content of approx. 22% -24% passes from a depot 1 into a drum screen 2, where very coarse impurities are removed. This is followed by further pre-cleaning in a separator / classifier 3 in order to separate stones, sand but also light impurities such as paper, straw or loose shells. The design of the pre-cleaning depends on the degree of contamination of the raw rice delivered. It is advantageous to largely separate loose impurities and additives from the paddy rice before further treatment.

Nach der Vorreinigung und kurzfristigen Zwischenlagerung in einem weiteren Depot 4 gelangt der Reis in einen ersten Wirbelschichtapparat 5, in der eine Reisschichtung von unten von warmer Luft durchströmt, auf mindestens ca. 5O0C erwärmt und um ca. 3-4% Feuchte getrocknet wird. Anschliessend gelangt der Reis direkt in einen zweiten Wirbelschichtapparat 6, in dem die Temperatur erhöht wird und eine Trocknung um weitere 3-4% Feuchte erfolgt, so dass ein Feuchtegehalt von ca. 18% erreicht wird. After the pre-cleaning and short-term intermediate storage in a further Depot 4 of the rice enters into a first fluidized bed apparatus 5, in which a rice layering of flows of hot air down, heated to at least about 5O 0 C and is dried to about 3-4% moisture . The rice then passes directly into a second fluidized bed apparatus 6, in which the temperature is raised and drying takes place by a further 3-4% moisture, so that a moisture content of approximately 18% is achieved.

Nachfolgend gelangt der Paddy in einen nicht explizit dargestellten Abstehbehälter 7, wo ein erstes Tempern vorgenommen wird. Nachfolgend gelangt der Paddy zum Nachtrocknen in einen dritten, nicht dargestellten Wirbelschichtapparat und anschliessend in einen weiteren Abstehbehälter für ein zweites Tempern. Auf dieses zweite Tempern folgt ein weiterer Trocknungsschritt in einem vierten Wirbelschichtapparat, dem sich ein drittes Tempern anschliesst. The paddy subsequently arrives in a stand-off container 7, which is not explicitly shown, where a first tempering is carried out. The paddy then arrives in a third fluidized bed apparatus (not shown) for subsequent drying and then in another stand-off container for a second tempering. This second tempering is followed by a further drying step in a fourth fluidized bed apparatus, which is followed by a third tempering.

Darauf folgend gelangt der Paddy in eine weitere Silozelle, wo der Paddy im Gegenluft- strom auf ca. 350C gekühlt und gleichzeitig um nochmals ca. 1 % getrocknet wird, so dass eine Endfeuchte von ca. 12,5%-13% erreicht wird. Bei diesem kombinierten Küh- lungs- und Trocknungsschritt wird die Verdunstungskälte des Wassers (im Paddy) genutzt, wodurch die erforderlichen Luftmengen deutlich reduziert werden können. In der letztgenannten Silozelle sind Niveau- und/oder Temperatursonden angeordnet um bestimmte Produkthöhen bei definierter Verweilzeit zu erreichen. Subsequently, the Paddy passes into a further silo where the Paddy in the reverse air current to about 35 0 C and cooled simultaneously to again about 1% is dried to a final moisture content of about 12.5% -13% is achieved becomes. In this combined cooling and drying step, the evaporative cooling of the water (in the paddy) is used, whereby the required air volumes can be significantly reduced. Level and / or temperature probes are arranged in the latter silo cell in order to achieve certain product heights with a defined dwell time.

In jeder Trocknungsstufe (Vor- und Nachtrocknung) wird der Paddy erwärmt, so dass sich der Paddy immer in einem gummielastischen Zustand befindet. The paddy is heated in each drying stage (pre- and post-drying) so that the paddy is always in a rubber-elastic state.

Alternativ zum Tempern kann die Kühlung des Reises (mit oder ohne Vorkühlung im zweiten Wirbelschichtapparat 6) auch schneller in einem Gegenstromkühler erfolgen, beispielsweise innerhalb von ca. 15 Minuten. As an alternative to tempering, the rice can also be cooled more quickly (with or without pre-cooling in the second fluidized bed apparatus 6) in a countercurrent cooler, for example within about 15 minutes.

Gegenüber konventionellen Verfahren ergab sich eine deutliche Reduzierung des Kornbruchs bei drastisch verringerten Trocknungszeiten. Auch ist der Unterhalfder Anlage weniger aufwendig und auf Grund der geringen Trocknungszeiten kann der Rohreis schneller eingelagert werden bzw. es kann mehr Reis zur Erntezeit erworben werden. Compared to conventional processes, there was a significant reduction in grain breakage with drastically reduced drying times. The Unterhalfder plant is also less complex and due to the short drying times, the paddy rice can be stored faster or more rice can be purchased at harvest time.

In einer weiteren Ausführungsform wird sehr feuchter Rohreis (z.B. mit einer Eingangsfeuchte von ca. 37%) in einem Dächertrockner mit Fluidbett in mehreren Stufen getrocknet. Die erste Stufe kann bereits mit Heissdampf von ca. 12O0C über 3 Stunden erfolgen. Die Feuchte wird dabei auf ca. 20-22% reduziert. In weiteren Stufen über jeweils 1 Stunde wird bei schrittweise gedrosselter Dampfzufuhr weiter getrocknet wobei Luft- bzw. Dampftemperatur ebenfalls schrittweise bis auf 500C reduziert wird. Es resultiert ein Feuchtegehalt von ca. 13%. In einem letzten Schritt wird der Reis innerhalb ei- . ner halben Stunde auf Umgebungstemperatur gekühlt, wobei kein Dampf mehr zugeführt wird. Erreichbar ist ein Feuchtgehalt von ca. 12.5%. Bezugszeichen In a further embodiment, very moist raw rice (for example with an initial moisture content of approx. 37%) is dried in a roof dryer with a fluid bed in several stages. The first stage may already take place with superheated steam of about 12O 0 C for 3 hours. The humidity is reduced to approx. 20-22%. In further stages over 1 hour each, the steam supply is gradually reduced and the air or steam temperature is also gradually reduced to 50 ° C. The result is a moisture content of approx. 13%. In a final step, the rice is inside a. cooled to ambient temperature within half an hour, with no more steam being supplied. A moisture content of approx. 12.5% can be achieved. Reference numerals

Depot depot

Trommelsieb  Drum screen

Separator  separator

Depot  depot

Wirbelschichtapparat  Fluidized bed apparatus

Wirbelschichtapparat  Fluidized bed apparatus

Abstehbehälter  Storage container

Claims

Patentansprüche Claims 1. Verfahren zur kontinuierlichen Trocknung von Reis, insbesondere von Paddy, umfassend eine Vorreinigung des Reises und ein Trocknen mittels Warmluft, dadurch gekennzeichnet, dass der Reis nach der Vorreinigung in einer Wirbelschicht auf eine Temperatur von wenigstens 500C erwärmt und in mehreren Temperaturstufen getrocknet wird. 1. A process for the continuous drying of rice, in particular paddy, comprising a pre-cleaning of the rice and drying by means of warm air, characterized in that after the pre-cleaning the rice is heated in a fluidized bed to a temperature of at least 50 ° C. and dried in several temperature stages becomes. 2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Trocknung in der Wirbelschicht mehr als zwei Stufen, bevorzugt vier Stufen umfasst. 2. The method according to claim 1, characterized in that the drying in the fluidized bed comprises more than two stages, preferably four stages. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass auf die zweite und jede weitere Trocknungsstufe ein Tempern folgt. 3. The method according to claim 1 or 2, characterized in that an annealing follows on the second and each further drying stage. 4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass auf das letzte Tempern ein kombiniertes Kühlen und Trocknen folgt. 4. The method according to claim 3, characterized in that a combined cooling and drying follows the last annealing. 5. Verfahren nach einem der vorangehenden Ansprüche 1 bis 4, dadurch gekennzeichnet, dass der Reis bei einer Temperatur von mindestens 50-550C auf einen Feuchtegehait von ca. 14% getrocknet wird und danach auf eine Temperatur kleiner 35°C gekühlt und gleichzeitig auf eine Endfeuchte von ca. 13% getrocknet wird. 5. The method according to any one of the preceding claims 1 to 4, characterized in that the rice is dried at a temperature of at least 50-55 0 C to a moisture content of about 14% and then cooled to a temperature less than 35 ° C and simultaneously is dried to a final moisture content of approx. 13%. 6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Reis bei einer Temperatur von ca. 50-550C auf einen Feuchtegehalt von ca. 13% getrocknet und nach der Trocknung im Gegenstrom auf Umgebungstemperatur gekühlt wird. 6. The method according to any one of claims 1 to 5, characterized in that the rice is dried at a temperature of about 50-55 0 C to a moisture content of about 13% and is cooled in countercurrent to ambient temperature after drying. 7. Verfahren nach Anspruchi , dadurch gekennzeichnet, dass die Trocknung in mehreren Temperaturstufen unter Zufuhr von Heissdampf erfolgt. 7. The method according to claim i, characterized in that the drying takes place in several temperature stages with the supply of hot steam. 8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass in der ersten Stufe Heissdampf mit ca. 12O0C zugeführt wird, dessen Temperatur in den weiteren Stufen stufenweise auf bis ca. 50°C reduziert wird. 8. The method according to claim 7, characterized in that the temperature of which is gradually reduced in subsequent stages to about 50 ° C is supplied in the first step superheated steam with about 12O 0 C,. 9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass die Dampfzufuhr stufenweise gedrosselt wird. 9. The method according to claim 8, characterized in that the steam supply is throttled in stages. 10. Einrichtung zur kontinuierlichen Trocknung von Reis, insbesondere von Paddy, umfassend eine Vorreinigung des Reises und Mittel zur Trocknung des Reises mittels erwärmter Luft, dadurch gekennzeichnet, dass das Mittel zur Trocknung mindesten zwei Wirbelschichtapparat (5, 6) umfasst. 10. Device for the continuous drying of rice, in particular paddy, comprising a preliminary cleaning of the rice and means for drying the rice by means of heated air, characterized in that the means for drying comprises at least two fluidized bed apparatus (5, 6). 11. Einrichtung nach Anspruch 10, dadurch gekennzeichnet, dass zwei Wirbelschichtapparate (5, 6) nacheinander angeordnet vorgesehen sind. 11. The device according to claim 10, characterized in that two fluidized bed apparatus (5, 6) are arranged one after the other. 12. Einrichtung nach Anspruch 11 , dadurch gekennzeichnet, dass dem zweiten Wirbelschichtapparat (6) mehrere Behälter zum Tempern von Paddy nachgeordnet sind, wobei den ersten zwei Behältern jeweils ein Mittel zur Reistrocknung nachgeschaltet ist. 12. Device according to claim 11, characterized in that the second fluidized bed apparatus (6) is followed by a plurality of containers for annealing paddy, the first two containers each being followed by a means for drying rice. 13. Einrichtung nach einem der Ansprüche 10 bis 12, dadurch gekennzeichnet, dass nach dem letzten Behälter zum Tempern eine Silozelle angeordnet ist, die Mittel zum Durchblasen von Kühlmedien, insbesondere Luft enthält. 13. Device according to one of claims 10 to 12, characterized in that a silo cell is arranged after the last container for tempering, which contains means for blowing cooling media, in particular air. 14. Einrichtung nach Anspruch 13, dadurch gekennzeichnet, dass die Silozelle Mittel zur Temperatur- und/oder Niveauermittlung enthält. 14. Device according to claim 13, characterized in that the silo cell contains means for temperature and / or level determination. 15. Einrichtung nach mindestens einem der Ansprüche 10 bis 14, dadurch gekennzeichnet, dass der Wirbelschichtapparat ein Dächertrockner ist. 15. Device according to at least one of claims 10 to 14, characterized in that the fluidized bed apparatus is a roof dryer.
PCT/CH2006/000645 2005-12-09 2006-11-15 Process and unit for continuous drying of rice Ceased WO2007065279A1 (en)

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WO2009111900A3 (en) * 2008-03-12 2010-09-23 Bühler AG Method for producing rice
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CN111336771B (en) * 2020-03-03 2021-08-03 济宁学院 A kind of grain drying device and method

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