EP0631820B1 - Process for operating a screw centrifuge - Google Patents
Process for operating a screw centrifuge Download PDFInfo
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- EP0631820B1 EP0631820B1 EP94107900A EP94107900A EP0631820B1 EP 0631820 B1 EP0631820 B1 EP 0631820B1 EP 94107900 A EP94107900 A EP 94107900A EP 94107900 A EP94107900 A EP 94107900A EP 0631820 B1 EP0631820 B1 EP 0631820B1
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- Prior art keywords
- centrifuge
- conveyor
- drum
- helix
- screw
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- 238000000034 method Methods 0.000 title claims description 10
- 239000007787 solid Substances 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 3
- 230000001133 acceleration Effects 0.000 claims description 2
- 239000012530 fluid Substances 0.000 claims 5
- 238000000605 extraction Methods 0.000 claims 2
- 230000005484 gravity Effects 0.000 claims 1
- 239000007788 liquid Substances 0.000 description 37
- 239000000126 substance Substances 0.000 description 14
- 239000004744 fabric Substances 0.000 description 6
- 239000008247 solid mixture Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 241000237858 Gastropoda Species 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
- B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
- B04B1/2016—Driving control or mechanisms; Arrangement of transmission gearing
Definitions
- the invention relates to a method for operating screw centrifuges for the Separation of liquid-solid mixtures directed, consisting of a centrifuge drum, which is rotatably mounted about its longitudinal axis and the one coaxially arranged, rotating with different speed (leading or lagging) Conveying screw encloses the screw spirals on a screw drum are attached, wherein means for feeding the mixture to be separated in the centrifuge drum along its axis and on opposite Ends of the centrifuge drum openings for the discharge of the separated light and heavy materials are provided, the radial distance from the centrifuge drum shaft axis is less than the distance of the centrifuge drum wall from the centrifuge drum axis, so that when the screw centrifuge is operating under the influence of the centrifugal force inside the centrifuge drum Forms liquid ring.
- the separation takes place in this liquid ring under the influence of the centrifugal force in specifically heavy and in specifically light substances instead, whereby the specifically heavy substances (the solids) on the outer edge of the ring, i.e. on the centrifuge drum wall and the specifically light substances (the Layer) in the inner area of the ring.
- DE-A-25 51 788 describes a screw centrifuge with a screw conveyor rotating with respect to the drum at a differential speed, both the centrifuge drum and the screw being driven by a hydraulic motor. It is now known to brake the centrifuge drum, whereby the contents of the drum are completely emptied and the liquid reaches the solids discharge or the other end of the drum, depending on the direction of incline of the screw.
- US-A-4,978,331 also describes a screw centrifuge with respect to the Drum with differential speed rotating screw conveyor.
- the centrifuge When switching off the centrifuge is first switched off the drum drive motor. Hereby there is a maximum differential speed between the drum and the screw conveyor, which removes the remaining content from the screw conveyor becomes. Only then is the drive motor of the screw conveyor switched off. The drum or the screw conveyor will not slow down made, but only the respective drive motor switched off. Also this is only about emptying or clearing out one as completely as possible Screw centrifuge when it is switched off. In no way is it guaranteed that when turning off the screw centrifuge is not undesirable Liquid is flushed out through the solids discharge openings.
- the invention is therefore based on the object of a method for operating To create screw centrifuges, with which avoided when turning off the centrifuge is that in the centrifugal force field from the solid-liquid mixture separated light phase, i.e. the liquid gushing through the solids discharge openings is washed out.
- the collapsing Liquid ring also discharged on the solids discharge side of the centrifuge is and undesirably gets back into the separated solid proposed according to the invention, immediately before reaching the centrifuge speed, where the corresponding centrifugal force corresponds to the gravitational force, to change the speed of the screw conveyor suddenly.
- the measure is taken because the liquid ring revolves at drum speed sudden speed change due to its inertia can not follow and itself thus the difference in speed between the rotating liquid ring and the screw conveyor reverses, also the direction of conveyance in relation to the Liquid ring vice versa. Now if the liquid ring breaks down, the liquid screws itself along the spiral path of the screw conveyor Liquid discharge so that no liquid at the solids discharge openings Centrifuge is discharged.
- the conveying effect of screw conveyors is based on a speed difference between the screw conveyor and the material to be conveyed, the direction of conveyance by the direction of rotation and by the direction of the spiral of the screw conveyor is determined.
- the Speed of the screw conveyor is greater than the speed of the with the centrifuge drum circulating material to be conveyed, the heavy substances, which means that they Screw conveyor according to the direction of the spiral to one end of the Centrifuge are promoted.
- the liquid ring rotating with the centrifuge drum keeps as a result of it Sluggishness initially increases its speed, but is now faster than the braked one Screw conveyor, which causes the direction of conveyance towards the other Reverse end of the centrifuge.
- the liquid "screws up" the end of the centrifuge, at which the discharge openings for the light substances are arranged, and no occurs at the discharge openings for the heavy substances Liquid.
- the Speed of the screw conveyor is lower than the speed of the centrifuge drum (the direction of rotation of the centrifuge drum and screw conveyor or the direction the spiral of the screw conveyor runs in reverse to the screw centrifuge with leading screw conveyor), so that there is also a transport in the direction to the discharge openings for the heavy substances.
- the measure according to the invention thus successfully prevents when the liquid ring collapses, there is also liquid at the discharge opening (6) for the heavy substances (10) is also carried out.
- the invention is not only based on the embodiment shown in the drawing figure a countercurrent screw centrifuge, but also limited to other screw centrifuges, e.g. B. DC screw centrifuges, screen screw centrifuges etc. applicable, the screw conveyor with leading or lagging speed are driven.
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- Centrifugal Separators (AREA)
Description
Die Erfindung ist auf ein Verfahren zum Betrieb von Schneckenzentrifugen für die Trennung von Flüssigkeit-Feststoffgemische gerichtet, bestehend aus einer Zentrifugentrommel, die um ihre Längsachse drehbar gelagert ist und die eine koaxial angeordnete, mit abweichender Drehzahl (voreilend oder nacheilend) umlaufende Förderschnecke umschließt, deren Schneckenwendeln auf einer Schneckentrommel befestigt sind, wobei Einrichtungen zum Zuführen des zu trennenden Gemisches in die Zentrifugentrommel längs deren Achse sowie an entgegengesetzten Enden der Zentrifugentrommel Öffnungen für den Austrag der getrennten leichten und schweren Stoffe vorgesehen sind, deren radialer Abstand von der Zentrifugentrommelwellenachse geringer ist als der Abstand der Zentrifugentrommelwand von der Zentrifugentrommelachse, so daß sich beim Betrieb der Schneckenzentrifuge unter dem Einfluß der Zentrifugalkraft innerhalb der Zentrifugentrommel ein Flüssigkeitsring ausbildet.The invention relates to a method for operating screw centrifuges for the Separation of liquid-solid mixtures directed, consisting of a centrifuge drum, which is rotatably mounted about its longitudinal axis and the one coaxially arranged, rotating with different speed (leading or lagging) Conveying screw encloses the screw spirals on a screw drum are attached, wherein means for feeding the mixture to be separated in the centrifuge drum along its axis and on opposite Ends of the centrifuge drum openings for the discharge of the separated light and heavy materials are provided, the radial distance from the centrifuge drum shaft axis is less than the distance of the centrifuge drum wall from the centrifuge drum axis, so that when the screw centrifuge is operating under the influence of the centrifugal force inside the centrifuge drum Forms liquid ring.
Bei der Trennung von Flüssigkeit-Feststoffgemische in Schneckenzentrifugen bildet sich unter dem Einfluß der durch die Drehung der Schneckenzentrifuge hervorgerufenen Zentrifugalkraft, die ein mehrfaches der Gravitationskraft ist, innerhalb der Zentrifugentrommel ein Ring aus dem zu trennenden Flüssigkeit-Feststoffgemisch aus, der vorwiegend aus bereits abgetrennter Flüssigkeit besteht und dessen Innendurchmesser durch die radiale Anordnung der Austragsöffnungen für die leichten Stoffe (z. B. der abgetrennten Flüssigkeit) bestimmt ist.When separating liquid-solid mixtures in screw centrifuges under the influence of those caused by the rotation of the screw centrifuge Centrifugal force, which is a multiple of the gravitational force, within the centrifuge drum a ring from the liquid-solid mixture to be separated from, which mainly consists of already separated liquid and whose inner diameter by the radial arrangement of the discharge openings for the light substances (e.g. the separated liquid) is determined.
In diesem Flüssigkeitsring findet unter dem Einfluß der Zentrifugalkraft die Trennung in spezifisch schwere und in spezifisch leichte Stoffe statt, wobei sich die spezifisch schweren Stoffe (die Feststoffe) am äußeren Rand des Ringes, also an der Zentrifugentrommelwand anordnen und die spezifisch leichten Stoffe (die Flüssigkeit) im inneren Bereich des Ringes sich darüber schichten.The separation takes place in this liquid ring under the influence of the centrifugal force in specifically heavy and in specifically light substances instead, whereby the specifically heavy substances (the solids) on the outer edge of the ring, i.e. on the centrifuge drum wall and the specifically light substances (the Layer) in the inner area of the ring.
Von den Schneckenwendeln der Förderschnecke, die je nach Drehrichtung der Zentrifuge gegenüber der Drehzahl der Zentrifugentrommel nacheilend oder voreilend in gleicher Drehrichtung in Drehung versetzt ist, werden die schweren Stoffe erfaßt und zu einem Ende der Zentrifuge transportiert, wo sie durch entsprechende Öffnungen aus der Zentrifuge austreten. Die leichten Stoffe fließen zum entgegengesetzten Ende der Zentrifuge zu den dort angeordneten Austragsöffnungen, wobei sie durch die aus den Schneckenwendeln der Förderschnecke gebildeten Kanäle zumindest teilweise entgegen der Förderrichtung der Förderschnecke fließen.From the screw spirals of the screw conveyor, which, depending on the direction of rotation of the Centrifuge lagging behind the speed of the centrifuge drum or the heavier ones are set in rotation in the same direction of rotation Substances are captured and transported to one end of the centrifuge, where they are passed through Exit openings from the centrifuge. The light fabrics flow to the opposite end of the centrifuge to the discharge openings arranged there, being carried out by the screw augers of the screw conveyor formed channels at least partially against the conveying direction of the screw conveyor flow.
Beim Abstellen der Zentrifuge verringert sich die Drehzahl der Zentrifuge bis zum Stillstand und damit verringert sich auch die Zentrifugalkraft. Es wird dabei eine Drehzahl erreicht, bei der die Zentrifugalkraft niedriger wird als die Gravitationskraft mit der Folge, daß der in der Zentrifuge sich ausgebildete Flüssigkeitsring "zusammenbricht" und der Füllstand innerhalb der Zentrifuge über die Austragsöffnungen für die schweren Stoffe (Feststoffe) hinausreicht, so daß an diesen Öffnungen - wenn auch nur kurzfristig - schwallartig auch die leichten Stoffe austreten. Hierdurch wird nicht nur das Trennergebnis verschlechtert, sondern es sind auch verfahrenstechnische Störungen bei der weiteren Verarbeitung der schweren Stoffe zu erwarten. When the centrifuge is switched off, the speed of the centrifuge decreases up to to a standstill and thus the centrifugal force also decreases. It will be there reaches a speed at which the centrifugal force becomes lower than the gravitational force with the result that the liquid ring formed in the centrifuge "collapses" and the level inside the centrifuge through the discharge openings for the heavy substances (solids) extends, so that at these Openings - even if only for a short time - gush out even the light fabrics. This not only worsens the separation result, but it are also procedural disturbances in the further processing of the heavy fabrics to be expected.
Andererseits sind beim Abstellen von Schneckenzentrifugen Techniken bekannt, durch deren Anwendung eine möglichst vollständige Entleerung der Zentrifugentrommel vom Trommelinhalt Feststoff und Flüssigkeit erreicht werden soll. So beschreibt die DE-A-25 51 788 eine Schneckenzentrifuge mit gegenüber der Trommel mit Differenzdrehzahl umlaufender Förderschnecke, wobei sowohl die Zentrifugen- Trommel als auch die Schnecke von einem Hydraulikmotor angetrieben sind. Bekannt ist es nun, die Zentrifugen- Trommel abzubremsen, wodurch die Trommel von seinem Inhalt vollständig entleert wird und die Flüssigkeit je nach Steigungsrichtung der Schnecke zum Feststoffaustrag oder zum anderen Ende der Trommel gelangt. Bei dieser bekannten Schneckenzentrifuge ist also gerade nicht sichergestellt, daß beim Abstellen der Schneckenzentrifuge Flüssigkeit in unerwünschter Weise durch die Feststoffaustragsöffnungen hinausgespült wird. Außerdem geht nicht hervor, wie und genau wann beim Betrieb der bekannten Schneckenzentrifuge das Abbremsen der Trommel erfolgt.On the other hand, when turning off screw centrifuges, techniques are known which, by means of their use, are intended to empty the centrifuge drum as completely as possible of the solid and liquid drum contents. For example, DE-A-25 51 788 describes a screw centrifuge with a screw conveyor rotating with respect to the drum at a differential speed, both the centrifuge drum and the screw being driven by a hydraulic motor. It is now known to brake the centrifuge drum, whereby the contents of the drum are completely emptied and the liquid reaches the solids discharge or the other end of the drum, depending on the direction of incline of the screw. In this known screw centrifuge, it is therefore not precisely ensured that liquid is flushed out through the solids discharge openings in an undesired manner when the screw centrifuge is switched off. In addition, it is not clear how and exactly when the known screw centrifuge is used to brake the drum.
Auch die US-A-4,978,331 beschreibt eine Schneckenzentrifuge mit gegenüber der Trommel mit Differenzdrehzahl umlaufender Förderschnecke. Beim Abschalten der Zentrifuge wird zunächst der Trommelantriebsmotor abgeschaltet. Hierdurch ergibt sich eine maximale Differenzdrehzahl zwischen der Trommel und der Förderschnecke, wodurch restliches Inhaltsmaterial von der Förderschnecke ausgeräumt wird. Erst dann wird der Antriebsmotor der Förderschnecke abgeschaltet. Eine Abbremsung der Trommel oder der Förderschnecke wird nicht vorgenommen, sondern lediglich der jeweilige Antriebsmotor ausgeschaltet. Auch hier geht es nur um das möglichst vollständige Entleeren bzw. Ausräumen einer Schneckenzentrifuge bei deren Abschaltung. Keinesfalls ist dabei gewährleistet, daß beim Abstellen der Schneckenzentrifuge nicht in unerwünschter Weise Flüssigkeit durch die Feststoffaustragsöffnungen hinausgespült wird.US-A-4,978,331 also describes a screw centrifuge with respect to the Drum with differential speed rotating screw conveyor. When switching off the centrifuge is first switched off the drum drive motor. Hereby there is a maximum differential speed between the drum and the screw conveyor, which removes the remaining content from the screw conveyor becomes. Only then is the drive motor of the screw conveyor switched off. The drum or the screw conveyor will not slow down made, but only the respective drive motor switched off. Also this is only about emptying or clearing out one as completely as possible Screw centrifuge when it is switched off. In no way is it guaranteed that when turning off the screw centrifuge is not undesirable Liquid is flushed out through the solids discharge openings.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zum Betrieb von Schneckenzentrifugen zu schaffen, mit dem beim Abstellen der Zentrifuge vermieden ist, daß die im Zentrifugalkraftfeld aus dem Feststoff- Flüssigkeitsgemisch abgetrennte leichte Phase, sprich die Flüssigkeit schwallartig durch die Feststoffaustragsöffnungen hinausgespült wird.The invention is therefore based on the object of a method for operating To create screw centrifuges, with which avoided when turning off the centrifuge is that in the centrifugal force field from the solid-liquid mixture separated light phase, i.e. the liquid gushing through the solids discharge openings is washed out.
Diese Aufgabe wird erfindungsgemäß mit einem Verfahren mit den kennzeichnenden Merkmalen des Anspruchs 1 gelöst. Vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen angegeben.This object is achieved with a method with the characteristic Features of claim 1 solved. Advantageous embodiments of the invention are specified in the subclaims.
Um zu verhindern, daß beim Abstellen einer Schneckenzentrifuge, wenn die Zentrifugalkraft gleich oder niedriger als die Gravitationskraft wird, der zusammenbrechende Flüssigkeitsring auch an der Feststoffaustragsseite der Zentrifuge ausgetragen wird und unerwünscht wieder in den abgetrennten Feststoff gelangt, wird erfindungsgemäß vorgeschlagen, unmittelbar vor Erreichen der Zentrifugendrehzahl, bei der die entsprechende Zentrifugalkraft der Gravitationskraft entspricht, die Drehzahl der Förderschnecke kurzfristig schlagartig zu ändern. Durch diese Maßnahme wird, da der mit Trommeldrehzahl umlaufende Flüssigkeitsring dieser plötzlichen Drehzahländerung infolge seiner Trägheit nicht folgen kann und sich somit die Differenzgeschwindigkeit zwischen dem umlaufenden Flüssigkeitsring und der Förderschnecke umkehrt, auch die Förderrichtung bezogen auf den Flüssigkeitsring umgekehrt. Wenn nun der Flüssigkeitsring zusammenbricht, schraubt sich die Flüssigkeit entlang der Wendelbahn der Förderschnecke zum Flüssigkeitsaustrag, so daß keine Flüssigkeit an den Feststoffaustragsöffnungen der Zentrifuge ausgetragen wird. To prevent turning off a screw centrifuge when the centrifugal force becomes the same or lower than the gravitational force, the collapsing Liquid ring also discharged on the solids discharge side of the centrifuge is and undesirably gets back into the separated solid proposed according to the invention, immediately before reaching the centrifuge speed, where the corresponding centrifugal force corresponds to the gravitational force, to change the speed of the screw conveyor suddenly. Through this The measure is taken because the liquid ring revolves at drum speed sudden speed change due to its inertia can not follow and itself thus the difference in speed between the rotating liquid ring and the screw conveyor reverses, also the direction of conveyance in relation to the Liquid ring vice versa. Now if the liquid ring breaks down, the liquid screws itself along the spiral path of the screw conveyor Liquid discharge so that no liquid at the solids discharge openings Centrifuge is discharged.
Die Förderwirkung von Förderschnecken beruht auf einem Drehzahlunterschied zwischen der Förderschnecke und dem zu fördernden Gut, wobei die Förderrichtung durch die Drehrichtung und durch die Richtung der Wendelung der Förderschnecke bestimmt ist.The conveying effect of screw conveyors is based on a speed difference between the screw conveyor and the material to be conveyed, the direction of conveyance by the direction of rotation and by the direction of the spiral of the screw conveyor is determined.
Beim Betrieb von Schneckenzentrifugen mit voreilender Förderschnecke ist die Drehzahl der Förderschnecke größer als die Drehzahl des mit der Zentrifugentrommel umlaufenden Fördergutes, den schweren Stoffen, wodurch diese von der Förderschnecke entsprechend der Richtung der Wendelung zu einem Ende der Zentrifuge gefördert werden.When operating screw centrifuges with a leading screw conveyor, the Speed of the screw conveyor is greater than the speed of the with the centrifuge drum circulating material to be conveyed, the heavy substances, which means that they Screw conveyor according to the direction of the spiral to one end of the Centrifuge are promoted.
Wenn nun beim Abstellen der Zentrifuge, und zwar dann, wenn die Drehzahl der Zentrifugentrommel soweit abgesunken ist, daß das Zusammenbrechen des Flüssigkeitsringes unmittelbar bevorsteht, erfindungsgemäß die Drehzahl der Förderschnecke kurzfristig schlagartig geändert wird und zwar bei voreilender Förderschnecke durch deren Abbremsung, spielt sich folgender Vorgang innerhalb der Zentrifuge ab:If now when turning off the centrifuge, namely when the speed of the Centrifuge drum has dropped so far that the collapse of the liquid ring imminent, according to the invention the speed the screw conveyor is suddenly changed at short notice with a leading screw conveyor by braking it, the following takes place Process inside the centrifuge from:
Der mit der Zentrifugentrommel umlaufende Flüssigkeitsring behält infolge seiner Trägheit zunächst seine Geschwindigkeit bei, ist aber nun schneller als die abgebremste Förderschnecke, wodurch sich die Förderrichtung in Richtung zum anderen Ende der Zentrifuge hin umkehrt.The liquid ring rotating with the centrifuge drum keeps as a result of it Sluggishness initially increases its speed, but is now faster than the braked one Screw conveyor, which causes the direction of conveyance towards the other Reverse end of the centrifuge.
Wenn der Flüssigkeitsring nun zusammenbricht, "schraubt" sich die Flüssigkeit zu dem Ende der Zentrifuge, an dem die Austragsöffnungen für die leichten Stoffe angeordnet sind, und an den Austragsöffnungen für die schweren Stoffe tritt keine Flüssigkeit aus.If the liquid ring now collapses, the liquid "screws up" the end of the centrifuge, at which the discharge openings for the light substances are arranged, and no occurs at the discharge openings for the heavy substances Liquid.
Beim Betrieb der Schneckenzentrifuge mit nacheilender Förderschnecke ist die Drehzahl der Förderschnecke kleiner als die Drehzahl der Zentrifugentrommel (die Drehrichtung von Zentrifugentrommel und Förderschnecke oder die Richtung der Wendelung der Förderschnecke verlaufen umgekehrt zur Schneckenzentrifuge mit voreilender Förderschnecke), so daß sich auch hier ein Transport in Richtung zu den Austragsöffnungen für die schweren Stoffe ergibt. When operating the screw centrifuge with a lagging screw conveyor, the Speed of the screw conveyor is lower than the speed of the centrifuge drum (the direction of rotation of the centrifuge drum and screw conveyor or the direction the spiral of the screw conveyor runs in reverse to the screw centrifuge with leading screw conveyor), so that there is also a transport in the direction to the discharge openings for the heavy substances.
Um die Transportrichtung der nacheilenden Förderschnecke beim Abstellen der Zentrifuge so umzukehren, daß beim Zusammenbrechen des Flüssigkeitsrings auch hier kein Austrag aus den Austragsöffnungen für die schweren Stoffe erfolgt, ist es nun erforderlich, daß der Flüssigkeitsring langsamer umläuft als die Förderschnecke. Erfindungsgemäß wird dies dadurch erreicht, daß die Drehzahl der Förderschnecke durch eine Beschleunigung kurzfristig nochmals schlagartig erhöht wird, wodurch sich nun auch hier der zusammenbrechende Flüssigkeitsring zu den Austragsöffnungen für die leichten Stoffe "schraubt", da der Flüssigkeitsring aufgrund seiner Trägheit vorerst seine langsame Geschwindigkeit beibehält.The direction of transport of the lagging screw conveyor when the centrifuge is switched off to reverse that when the liquid ring collapses there is also no Discharge from the discharge openings for the heavy substances, it is now necessary that the liquid ring rotates more slowly than the screw conveyor. According to the invention this is achieved in that the speed the screw conveyor suddenly increased again suddenly due to acceleration becomes, whereby the collapsing liquid ring to the Discharge openings for the light fabrics "screw" because of the liquid ring maintains its slow speed for the time being due to its inertia.
Weitere Einzelheiten und Merkmale der Erfindung werden anhand eines Anwendungsbeispiels in einer Zeichnungsfigur näher erläutert.Further details and features of the invention are based on an application example explained in more detail in a drawing figure.
In der Zeichnungsfigur ist eine an sich bekannte Vollmantelschneckenzentrifuge (1) in Gegenstromausführung mit voreilender Förderschnecke (4) dargestellt. Das zu trennende Flüssigkeit-Feststoffgemisch wird durch die Zuführeinrichtung (14) längs der Drehachse in die Schneckenzentrifuge (1) eingebracht und gelangt durch die Öffnungen (7) in den aus der Zentrifugentrommel (2) und der Schneckentrommel (13) gebildeten Trennraum. Aufgrund der auf das eingebrachte Gemisch wirkenden Zentrifugalkraft und der stattfindender Trennung bildet sich ein Flüssigkeitsring aus, dessen äußerer Durchmesser dem Innendurchmesser der Zentrifugentrommel (2) entspricht und dessen Innendurchmesser durch die Stellung des Wehrs (8) der Austragsöffnung (5) für die leichten Stoffe (Flüssigkeit) gegeben ist und in der Zeichnungsfigur der gestrichelten Linie (9) entspricht.In the drawing figure is a well-known solid-bowl screw centrifuge (1) shown in counter-current version with leading screw conveyor (4). The liquid-solid mixture to be separated is passed through the feed device (14) introduced into the screw centrifuge (1) along the axis of rotation and arrives through the openings (7) in the centrifuge drum (2) and Snail drum (13) formed separation space. Because of the brought in Mixing centrifugal force and the separation that takes place is formed a liquid ring, the outer diameter of the inner diameter of the Centrifuge drum (2) corresponds and its inner diameter by the position weir (8) discharge opening (5) for light substances (liquid) is given and corresponds to the broken line (9) in the drawing.
Bei der erfindungsgemäßen schlagartigen Drehzahländerung durch Abbremsen der Förderschnecke (4), der der Flüssigkeitsring infolge einer Trägheit zunächst nicht folgt, "schraubt" sich der Flüssigkeitsring infolge seiner nun relativ zur Förderschnecke (4) schnelleren Drehzahl entgegen der Förderrichtung (in der Zeichnungsfigur nach rechts) in Richtung zu den Austragsöffnungen (5) für die leichten Stoffe hin (in der Zeichnungsfigur nach links). In the sudden speed change according to the invention by braking the screw conveyor (4), the liquid ring initially does not follow due to inertia, the liquid ring "screws" as a result its now faster relative speed to the screw conveyor (4) against the Direction of conveyance (to the right in the figure) towards the discharge openings (5) for the light fabrics (to the left in the figure).
Da wegen der begrenzten Kapazität der Austragsöffnungen (5) für die auszutragenden leichten Stoffe (11) nicht sofort alle Flüssigkeit ausgetragen werden kann, ergibt sich zunächst (bis der größte Teil der Flüssigkeit ausgetragen ist) ein neuer Flüssigkeitsring mit der Innenfläche (12), der sich gegen die linke Stirnwand der Zentrifugentrommel (2) drängt und sich somit von den Austragsöffnungen (6) für die schweren Stoffe (10) zurückzieht.Because of the limited capacity of the discharge openings (5) for the discharge light substances (11) not all liquid can be discharged immediately, there is initially a new one (until most of the liquid has been discharged) Liquid ring with the inner surface (12), which is against the left end wall of the Centrifuge drum (2) pushes itself and thus from the discharge openings (6) for withdraws the heavy fabrics (10).
Durch die erfindungsgemäße Maßnahme wird somit erfolgreich verhindert, daß beim Zusammenbrechen des Flüssigkeitsrings auch Flüssigkeit an der Austragsöffnung (6) für die schweren Stoffe (10) mit ausgetragen wird.The measure according to the invention thus successfully prevents when the liquid ring collapses, there is also liquid at the discharge opening (6) for the heavy substances (10) is also carried out.
Die Erfindung ist nicht nur auf das in der Zeichnungsfigur dargestellte Ausführungsbeispiel einer Gegenstromschneckenzentrifuge beschränkt, sondern auch auf andere Schneckenzentrifugen, so z. B. Gleichstromschneckenzentrifugen, Siebschneckenzentrifugen etc. anwendbar, deren Förderschnecken mit voreilender oder nacheilender Drehzahl angetrieben sind.The invention is not only based on the embodiment shown in the drawing figure a countercurrent screw centrifuge, but also limited to other screw centrifuges, e.g. B. DC screw centrifuges, screen screw centrifuges etc. applicable, the screw conveyor with leading or lagging speed are driven.
Claims (3)
- A method for the operation of helical conveyor centrifuges (1) for the separation of fluid-solid mixes, comprising a centrifuge drum (2), which is mounted so as to rotate about its longitudinal axis and which encloses a coaxially arranged conveyor helix (4), rotating at a different speed of rotation (leading or lagging), whose spirals are fixed to a helix drum (13), whereby arrangements are provided for the introduction of the mixture to be separated into the centrifuge drum along its axis and at opposite ends of the centrifuge drum openings (5, 6) for the extraction of the separated light and heavy materials, whose radial separation from the centrifuge drum axis is less than the distance of the centrifuge drum wall from the centrifuge drum axis, so that in operation of the helical conveyor centrifuge (1) a fluid ring forms under the influence of centrifugal force within the centrifuge drum (2), characterised in that on shutting down the centrifuge (1) immediately before the speed of centrifuge rotation is reached, at which the resultant centrifugal force corresponds to the force of gravity and below which a collapse of the fluid ring would occur, the rotational speed of the conveyor helix (4) is abruptly changed for a short time such that since the fluid ring, due to its inertia, does not follow this change of rotational speed, the direction of transport of the helix spirals (3) on the fluid ring is reversed and the collapsing fluid ring is transported with the aid of the helix (3) to the extraction opening (5) for the light material (11).
- A method in accordance with Claim 1, characterised in that with centrifuges (1) with faster running conveyor helices (4) the short abrupt change of rotational speed is brought about by a braking process of the conveyor helix (4).
- A method in accordance with Claim 1, characterised in that with centrifuges (1) with slower running conveyor helices (4) the short abrupt change of rotational speed is brought about by an acceleration of the conveyor helix (4).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4321964 | 1993-07-01 | ||
| DE4321964A DE4321964A1 (en) | 1993-07-01 | 1993-07-01 | Process for operating screw centrifuges |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0631820A2 EP0631820A2 (en) | 1995-01-04 |
| EP0631820A3 EP0631820A3 (en) | 1995-05-31 |
| EP0631820B1 true EP0631820B1 (en) | 1999-10-27 |
Family
ID=6491739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP94107900A Expired - Lifetime EP0631820B1 (en) | 1993-07-01 | 1994-05-21 | Process for operating a screw centrifuge |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5474515A (en) |
| EP (1) | EP0631820B1 (en) |
| DE (2) | DE4321964A1 (en) |
| DK (1) | DK0631820T3 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4439938A1 (en) | 1994-11-09 | 1996-05-15 | Kloeckner Humboldt Deutz Ag | Process for operating screw centrifuges |
| DE19952804C2 (en) * | 1999-11-02 | 2003-07-03 | Westfalia Separator Ind Gmbh | Solid bowl screw centrifuge for processing a centrifugal material that tends to foam |
| DE10220757B4 (en) * | 2002-05-08 | 2004-06-24 | Westfalia Separator Ag | Centrifuge, especially separator |
| DE10223802B4 (en) * | 2002-05-29 | 2005-06-09 | Westfalia Separator Ag | Solid bowl centrifuge |
| US6972411B2 (en) * | 2002-10-03 | 2005-12-06 | Schick Technologies, Inc. | Method of event detection for intraoral image sensor |
| KR100920449B1 (en) | 2007-10-04 | 2009-10-08 | 이강찬 | Centrifugal separator |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1632325B1 (en) * | 1967-06-02 | 1970-05-27 | Turbo Separator Ag | Continuously working, screenless screw centrifuge |
| US3494542A (en) * | 1968-05-27 | 1970-02-10 | Pennwalt Corp | Centrifuging process and apparatus |
| DE2063063C3 (en) * | 1970-12-22 | 1975-10-16 | Amberger Kaolinwerke Gmbh, 8452 Hirschau | Process for separating the solids from a suspension, as well as for promoting the internal transport and discharge of the thickened sludge in solid bowl centrifuges, as well as centrifuges serving to carry out the process |
| DE2125522A1 (en) * | 1971-05-22 | 1972-12-07 | Mse Holdings Ltd | Centrifugal separator - with by-pass chamber esp for machine tool coolant with swarf |
| DE2551788A1 (en) * | 1975-11-18 | 1977-06-02 | Flottweg Werk Bruckmayer | FULLY-SLEEVED SCREW CENTRIFUGE WITH DIFFERENTIAL SPEED-VARIABLE COUPLING BETWEEN SHEATH PART AND SCREW PART |
| SU582001A1 (en) * | 1976-06-23 | 1977-11-30 | Всесоюзный научно-исследовательский и проектный институт галургии | Method of automatic control of suspension separating process in screw-type settling centrifuge |
| DE2835108A1 (en) * | 1978-08-10 | 1980-02-14 | Lacher Jorge Halder | Releasing compacted sugar crystals from centrifuge screen - using sudden applied braking force to screen (BR 26.9.78) |
| DE3044797A1 (en) * | 1980-11-28 | 1982-07-01 | Fluormatic GmbH, 7407 Rottenburg | Removing solids from liq. using two centrifuges - superimposed in common casing and operated independently |
| US5176616A (en) * | 1989-06-29 | 1993-01-05 | Kloeckner-Humboldt-Deutz Aktiengesellschaft | Method and apparatus for the after-treatment of the thick material in the thick material discharge region of a solid bowl worm centrifuge |
| US4978331A (en) * | 1989-07-11 | 1990-12-18 | Alfa-Laval Ab | Method and apparatus for cleaning in place of a decanter centrifuge |
| DE4104752A1 (en) * | 1990-02-15 | 1991-08-22 | Krauss Maffei Ag | Dislodging deepening cake residue from centrifugal filter - by flooding surface before abrupt rotary speed change |
-
1993
- 1993-07-01 DE DE4321964A patent/DE4321964A1/en not_active Withdrawn
-
1994
- 1994-05-21 DE DE59408853T patent/DE59408853D1/en not_active Expired - Fee Related
- 1994-05-21 DK DK94107900T patent/DK0631820T3/en active
- 1994-05-21 EP EP94107900A patent/EP0631820B1/en not_active Expired - Lifetime
- 1994-06-28 US US08/267,561 patent/US5474515A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US5474515A (en) | 1995-12-12 |
| DE59408853D1 (en) | 1999-12-02 |
| DK0631820T3 (en) | 2000-01-17 |
| EP0631820A2 (en) | 1995-01-04 |
| EP0631820A3 (en) | 1995-05-31 |
| DE4321964A1 (en) | 1995-01-12 |
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