EP0317687A1 - Centrifugal pump for cryogenic fluids - Google Patents

Centrifugal pump for cryogenic fluids Download PDF

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Publication number
EP0317687A1
EP0317687A1 EP87810695A EP87810695A EP0317687A1 EP 0317687 A1 EP0317687 A1 EP 0317687A1 EP 87810695 A EP87810695 A EP 87810695A EP 87810695 A EP87810695 A EP 87810695A EP 0317687 A1 EP0317687 A1 EP 0317687A1
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EP
European Patent Office
Prior art keywords
pump inlet
inlet ring
pump
lamella
lamellae
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP87810695A
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German (de)
French (fr)
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EP0317687B1 (en
Inventor
Jean Elie Tornare
Klaus Bofinger
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Fives Cryomec AG
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Cryomec AG
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Publication date
Application filed by Cryomec AG filed Critical Cryomec AG
Priority to DE8787810695T priority Critical patent/DE3776570D1/en
Priority to EP19870810695 priority patent/EP0317687B1/en
Publication of EP0317687A1 publication Critical patent/EP0317687A1/en
Application granted granted Critical
Publication of EP0317687B1 publication Critical patent/EP0317687B1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/18Rotors
    • F04D29/22Rotors specially for centrifugal pumps
    • F04D29/2261Rotors specially for centrifugal pumps with special measures
    • F04D29/2277Rotors specially for centrifugal pumps with special measures for increasing NPSH or dealing with liquids near boiling-point

Definitions

  • the present invention relates to a pump inlet ring, in particular for pumps of cryogenic fluids.
  • a pump inlet ring for pumps of cryogenic fluids.
  • it For every liquid that is to be pumped, it must be ensured that the pressure in it on the pump inlet side does not drop so far that its vapor pressure is reached. If this happens, gas bubbles form immediately.
  • a liquid to be pumped must be kept at a pressure at any temperature which is sufficiently above its vapor pressure curve. For many liquids this is far because of their characteristic vapor pressure curves and due to the usual suction pressures at atmospheric pressure ensured.
  • cryogenic fluids are filled in pressure tanks in order to avoid the losses already mentioned as far as possible. Pumping out atmospheric tanks with cryogenic liquid content is therefore essential if you want to fill up a pressure tank. For example, the tanks on a truck for transporting such cryogenic fluids are kept at a pressure of about 3 bar.
  • Such a tank is of course also refilled under pressure, so that the fluid basically has to be pumped from a location of lower pressure to a location of higher pressure.
  • Pumps for such purposes have an impeller, which is usually preceded by a pump inlet ring, called an inducer in the international technical language.
  • This pump inlet ring is intended to slightly compress the fluid immediately in front of the pump impeller, i.e. to increase the NPSH.
  • Conventional pump inlet rings or inducers are usually built similar to an Archimedes screw. They have a central pipe section as an axis of rotation, on the periphery of which one or more screw blades wind around the pipe section in a serpentine fashion.
  • the pipe section is provided with a flow-optimized cap on the inlet side.
  • Practice shows that gas bubbles built in such a way form gas bubbles even at relatively low speeds. This fact has to do with the fluid flow forced by the pump inlet ring.
  • the fluid becomes significant changes in direction as it enters the pump ring forced, which cause corresponding turbulence in the fluid. Turbulent flow also occurs at the edges of the airfoils, which result in local pressure drops under the vapor pressure of the fluid. In the limit range of the permissible number of revolutions, gas bubbles form immediately, which cannot be eliminated again in the course of the fluid in such a conventional pump inlet ring.
  • a pump inlet ring in particular for pumps of cryogenic fluids, which is characterized in that it is essentially formed from a hollow cylindrical fitting which can be attached to a shaft on the pump side, and the other side of which is formed in the axial direction in lamellae with a slope, which lamellae end in one run out sharp edge and jointly form a swing basket, such that when the pump inlet ring rotates, liquid on the inlet side of the pump inlet ring can be detected by the lamella ends and can be conveyed axially backwards and radially outwards between the lamellae.
  • FIG. 1 The features of the pump inlet ring essential to the invention can be seen in FIG. 1. It is essentially formed from a hollow cylindrical shaped piece 1.
  • the wall of the hollow cylinder makes up about a quarter of the outside diameter. However, this size ratio can vary in both directions. Recesses are present in this hollow cylinder 1, so that helically extending lamellae 2 are formed which have a corresponding slope.
  • the optimal gradient and operating speed is influenced by the fluid to be pumped and varies accordingly.
  • the individual lamellae 2 are identical to one another and are all rooted in the wall of the hollow cylinder 1. Their ends 6 end in sharp edges 3, which are intended to "cut off" the incoming liquid to a certain extent. It goes without saying that the individual lamellae 2 must have a certain thickness when viewed in the running direction of the pump inlet ring in order to ensure their stability during operation.
  • the hollow cylindrical shaped piece 1 is tapered and ends in a bearing bush 12, by means of which the pump inlet ring 1 can be fastened on a shaft.
  • the bearing bush 12 can have a significantly smaller inner diameter than that of the hollow cylinder 1, which for this purpose is produced with different inner diameters on both sides.
  • the taper on the outside of the hollow cylinder 1 begins from the area of the lamellae 2, so that they extend into the taper and are rooted in it.
  • the lamella roots 14 are thus a little less wide than the actual lamellae, but the passages are created through the recesses between the lamellae 2, through which the liquid can exit axially from the pump inlet ring 1.
  • the fins 2 in the area of their ends 6 are encompassed in their entirety by an annular ring 8 on their periphery.
  • the outside 9 of the ring rim 8 is flush with the outside 10 of the hollow cylinder 1.
  • a labyrinth seal is formed by the grooves 11 in the outside 9 of the ring rim 8, the meaning of which will become clear later.
  • the inlet-side edge 15 of the ring rim 8 can lie in the same plane as the ends 6 of the lamellae 2, or their edge edges 3.
  • FIG. 2 the same pump inlet rim 1 is shown essentially seen from the inlet side.
  • the course of the individual lamellae 2 can be seen here, each of which extends helically with a certain slope towards its roots 14.
  • the ends 6 of the slats 2 are designed such that they each end in a sharp edge 3.
  • the directions in which these edges 3 run can also vary. If these are not radial, a better "cutting effect" is achieved.
  • the edges 3 can be twisted in both directions from the radial. These directions are naturally determined by the gradient of the lamella conveying surfaces 13 in the radia len direction in the area of the lamella ends 6.
  • the ring rim 8 which is designed here as a labyrinth seal, has an internal thread 16, by means of which it can be screwed onto the ends 6 of the lamellae 2 and can therefore be replaced.
  • grooves 17 are recessed in the axial direction, which are intended to transmit the torques from the pump shaft to the pump inlet ring 1.
  • FIG. 3 shows how the pump inlet ring 1 according to the invention is installed on the basis of a cross section of a corresponding pump for cryogenic fluids, which is however only partially shown.
  • the pump inlet ring 1 is attached with its bearing bush 12 to the pump shaft 18 and therefore rotates at the same speed as the actual pump impeller 19. However, it is also conceivable to drive the pump inlet ring 1 with a separate shaft, so that operating speeds other than those of the pump impeller 19 are also possible are.
  • the pump inlet rim 1 With its ring rim 8, the pump inlet rim 1 is sealed in a deflector 20, called diffuser in the international technical language. The sealing of the space in the area of the inlet of the pump inlet ring 1 from the space between the area where the fluid from the pump inlet ring 1 occurs, is necessary so that the compressed fluid does not run around the outside of the pump inlet ring 1 back again.
  • the deflector 20 itself is designed on its inside 21 in such a way that lamellae which extend helically are formed on it.
  • the slope of these deflector plates is exactly the opposite of that of the inducer plates 2.
  • the aforementioned reversal of the slope of the deflector plates ensures that the direction of movement of the fluid is deflected in the axial direction with respect to the pump axis.
  • the fluid arriving in front of the pump inlet ring 1 is thus, as it were, cut by the ends 6 of the lamellae 2, which are designed as blades.
  • the liquid captured by the slat ends 6 is then conveyed radially outward along the slat conveying surfaces 13 in the axial direction and additionally because of the rotation and the resulting centrifugal force. It is the centrifugal force that accelerates the fluid outwards towards the inner wall of the deflector 20, so that with a corresponding choice of the speed, the fluid is not only conveyed, but above all also compressed becomes.
  • the advantage of the pump inlet collar 1 according to the invention can largely be seen in the fact that the axis of rotation is free at the inlet. None stands in the way of the incoming fluid and therefore it is not forced to make abrupt changes in direction, which would cause turbulent flows. In addition, certain moments of danger are eliminated.
  • the lamellae 2 form an oscillating basket, which to a certain extent represents a sieve for any particles that are washed up.
  • an actual cup-like sieve made of a wire mesh can also be inserted inside the pump inlet ring 1.
  • This sieve can be screwed directly to the screw Pump ring 1 holds firmly on the pump shaft, be jammed.
  • the edge of the cup-shaped sieve can be drawn over the ends 6 of the lamellae 2, that is to say over its edges 3, and connect flush to the ring rim 8.
  • the edge can also only be drawn to the beginning of the slat ends 6, so that its edges 3 remain free so as not to impair the "cutting effect".
  • the particle therefore always remains trapped inside the pump inlet ring 1 and cannot generate any mechanical frictional heat. Due to the rotation, a constant compression of the fluid is achieved during the pumping of the inventive pump inlet ring 1, so that the formation of gas bubbles compared to conventional inducers up to higher density differences between the inlet and outlet area is avoided.
  • any cavities that nevertheless form will first occur in the area of the axis of rotation in the interior of the pump inlet ring 1, where they do not negatively influence the action of the inducer 1.
  • the fluid After exiting the inducer 1, the fluid reaches the deflector or diffuser 20 in compressed form and from there it is conveyed directly into the interior of the pump impeller 19.
  • the efficiency of the present pumps Inlet ring 1 can be decisively influenced by the special design of the slats 2.
  • the size ratios of the inside and outside diameter of the hollow cylinder 1 of the pump inlet ring 1, its length, the number of fins 2 and their thickness and pitch are important for the compression performance.
  • the design of the individual lamellae 2, especially their lamella conveying surfaces 13, also has an influence on the compression performance.
  • the design of the lamella ends 6 and the course of their peripheral edges 3 also determine how much liquid can be detected per revolution at a given pressure.
  • the fin conveying surfaces 13 can be concavely curved, as is shown in FIG. 4 in a side view of a pump inlet ring 1 according to the invention.
  • the curvature is advantageously designed in such a way that the radius of curvature decreases continuously towards the back against the lamella roots 14. Due to this shape of the lamella conveying surfaces 6, the pump inlet ring 1 has the character of a centrifugal basket 4.
  • FIG. 5 shows a partial section of a lamella 2, which is not only curved in a parabolic shape, but whose lamella conveying surface 13 also has a twist.
  • the surface 13 is gradually rotated towards the lamella root 14 towards the periphery of the pump inlet ring 1. This promotes emptying or ejection of the liquid conveyed in the radial direction, which is of course also suitable for increasing the compression effect towards the outside.
  • the pump inlet ring 1 according to the invention is advantageously cast. In measurement tests, such a pump inlet ring 1 was placed in front of the pump impeller upstream cryogenic pump, with which liquid nitrogen was then pumped out of an atmospheric tank at a temperature of -195.8 degrees C. A temperature of -186.7 degrees C was measured immediately at the pump inlet, which corresponds to an NPSH of zero. The corresponding vapor pressure there is 2.55 bar.
  • the pump could be started without problems and came immediately to pressure, that is, between pump inlet ring 1 and pump impeller 19, thanks to pump inlet ring 1, sufficient pressure was built up that the liquid in front of pump impeller 19 had a pressure that was above the vapor pressure curve. No cavitation was found.
  • inducers according to the invention cryogenic liquids can now be pumped out of atmospheric tanks, with an adequate "net positive suction head NPSH" being guaranteed.
  • Corresponding storage tanks can therefore stand at ground level more cost-effectively and therefore in many cases also much closer to the pump or wherever the cryogenic fluid is desired to be removed. However, this also brings about a reduction in heat absorption, since the cryogenic lines become shorter and expensive insulation becomes less extensive.
  • pump inlet rings according to the invention can be manufactured and used for left-hand or right-hand pumps.

Abstract

The crown-type pump inducer (1) essentially comprises a hollow cylindrical shaped part (1). This is tapered on the pump side and runs out into a bearing bush (12) by means of which the crown-type pump inducer (1) can be fixed on a shaft. On the inlet side the hollow cylinder (1) is formed into helical shaped plates (2) which together form a spinner basket (4). The ends (6) of the plates (2) are jointly enclosed by an annular rim (8) whose outside (9) is flush with the periphery (10) of the plates (2). The outside (9) of the annular rim (8) is formed as a labyrinth seal. The ends (6) of the plates (2) run out into sharp edges (3). The rotating crown-type pump inducer (1) gathers the incoming fluid on the inlet side and conveys it axially backwards and at the same time radially outwards, thereby compressing the fluid. <IMAGE>

Description

Die vorliegende Erfindung betrifft einen Pumpeneinlauf­kranz, insbesondere für Pumpen von cryogenen Fluida. Bei jeder Flüssigkeit, die gepumpt werden soll, muss sicher­gestellt werden, dass der Druck in ihr auf der Pumpen­einlaufseite nicht soweit abfällt, dass ihr Dampfdruck erreicht wird. Geschieht das nämlich, so bilden sich sofort Gasblasen. Man spricht von sogenannten Kavitäten in der zu pumpenden Flüssigkeit. Treten solche Kavitäten im Bereich des Pumpenlaufrades einer Pumpe auf, so fällt die Pumpleistung drastisch ab. Man sagt, die Pumpe steigt aus. Um diese Effekte zu vermeiden, muss eine zu pumpende Flüssigkeit bei jeder Temperatur auf einem Druck gehalten werden, der genügend weit über ihrer Dampfdruckkurve liegt. Bei vielen Flüssigkeiten ist das wegen deren charakteristischen Dampfdruckkurven und aufgrund der üblichen Ansaugdrucke bei atmosphärischem Druck weit­ gehend sichergestellt. Bei flüchtigeren Flüssigkeiten, besonders sogenannten cryogenen Fluida, wie dies zum Beispiel Stickstoff, Wasserstoff, Sauerstoff usw. in flüssiger Form sind, kommt man beim Pumpen sehr bald in jene Druckbereiche, wo unweigerlich Gasblasen entstehen, weil der Dampfdruck unterschritten wird. Es muss daher sichergestellt werden, dass immer eine genügende Druck­differenz zwischen dem aktuellen Druck des zu pumpenden Fluides und dessen Dampfdruck vorhanden ist. Man spricht in der Fachsprache von "Net Positiv Suction Head (NPSH)", eben dieser Druckdifferenz auf der Eingangsseite der Pumpe. Die erforderliche Grösse des "Net Positiv Suction Head (NPSH)" ist abhängig von der Grösse, des Typs und der Bauart der Pumpe und ist in der Regel an jener angegeben. Soll ein cryogenes Fluid aus einem atmosphä­rischen Tank gepumpt werden, so bestimmt diese Grösse des NPSH, wie hoch der Tank gegenüber der Pumpe angeordnet sein muss, um Kavitäten innerhalb des gepumpten Fluids zu vermeiden.
Im Anlagenbau ist die Erfüllung dieser Forderung natür­lich mit zusätzlichem Aufwand verbunden, kann doch damit ein Tank nicht beliebig am Boden plaziert werden, sondern muss in der Regel auf spezielle Stahlkonstruktionen hinauf gebaut werden. Gerade bei Tanks von Volumen mit einigen Tausend Litern ist das natürlich mit beträcht­lichen zusätzlichen Kosten verbunden. Aus Platzgründen muss ein solchermassen gelagerter Tank oft auch relativ weit entfernt von der Förderpumpe aufgestellt werden. Das wiederum bedingt eine äusserst gute und entsprechend kostspielige Isolation der Zufuhrleitung, da sonst durch Wärmeabsorption grosse Kälteverluste eintreten. Die Flüs­sigkeit im Tank absorbiert ohnehin ein gewisses Mass an wärme während ihrer Lagerung, was zur Folge hat, dass Flüssigkeit verdampft und der Druck im Tank ansteigen würde, wäre er nicht atmosphärisch, also über ein Ventil mit der Atmosphäre verbunden. Andrerseits aber wäre es viel zu teuer, Tanks von solchen Grössenordnungen als Drucktanks zu bauen. Für Transportzwecke werden cryogene Fluida aber in Drucktanks gefüllt, um die oben bereits erwähnten Verluste möglichst zu vermeiden. Das Abpumpen von atmosphärischen Tanks mit cryogenem Flüssig­keitsinhalt ist deshalb unumgänglich, will man einen Drucktank auffüllen. Zum Beispiel werden die Tanks auf einem Lastwagen zum Transport von solchen cryogenen Fluida auf einem Druck von etwa 3 bar gehalten. Das Auf­füllen eines solchen Tanks geschieht natürlich ebenfalls unter Druck, sodass also das Fluid grundsätzlich von einem Ort geringeren Drucks zu einem Ort höheren Drucks gepumpt werden muss. Die Druckdifferenz ist umso grösser, je tiefer der Flüssigkeitspegel im atmosphärischen Tank steht.
Pumpen für solche Zwecke weisen ein Laufrad auf, dem üblicherweise ein Pumpeneinlaufkranz, in der internatio­nalen Fachsprache Inducer genannt, vorgeschaltet ist. Dieser Pumpeneinlaufkranz soll das Fluid unmittelbar vor dem Laufrad der Pumpe etwas verdichten, also den NPSH er­höhen. Herkömmliche Pumpeneinlaufkränze oder Inducer sind in der Regel ähnlich einer Archimedesschraube gebaut. Sie weisen ein zentrales Rohrstück als Drehachse auf, an dessen Peripherie sich schlangenlinienförmig ein oder mehrere Schraubenblätter um das Rohrstück herum winden. Auf der Einlaufseite ist das Rohrstück mit einer strömungsgünstigen Kappe versehen.
Die Praxis zeigt, dass sich an solcherart gebauten Pum­peneinlaufkränzen schon bei relativ geringen Umdrehungs­zahlen Gasblasen bilden. Diese Tatsache hat mit der durch den Pumpeneinlaufkranz erzwungenen Strömung des Fluids zu tun. Zum ersten wird das Fluid beim Eintritt in den Pumpeneinlaufkranz zu beträchtlichen Richtungsänderungen gezwungen, welche entsprechende Turbulenzen im Fluid ver­ursachen. Auch an den Rändern der Schaufelblätter ent­steht turbulente Strömung, welche lokale Druckabfälle unter den Dampfdruck des Fluids nach sich ziehen. Im Grenzbereich der zulässigen Umdrehungszahlen bilden sich sofort Gasblasen, die im weiteren Verlauf des Fluids in einem solchen herkömmlichen Pumpeneinlaufkranz nicht wieder eliminiert werden können. Wird das Fluid einmal von den Schraubenblättern in axialer Richtung einge­schlossen und weiterbefördert, so ändert sich weder das Volumen der so gebildeten Förderkarmnern, noch wird darin die auf das Fluid einwirkende Beschleunigung geändert. Die Gasblasen können nicht mehr abgebaut werden und gelangen in das Pumpenlaufrad, wo sich die eingangs erwähnten Kavitäts-Effekte einstellen.
The present invention relates to a pump inlet ring, in particular for pumps of cryogenic fluids. For every liquid that is to be pumped, it must be ensured that the pressure in it on the pump inlet side does not drop so far that its vapor pressure is reached. If this happens, gas bubbles form immediately. One speaks of so-called cavities in the liquid to be pumped. If such cavities occur in the area of the pump impeller of a pump, the pump output drops drastically. They say the pump gets out. In order to avoid these effects, a liquid to be pumped must be kept at a pressure at any temperature which is sufficiently above its vapor pressure curve. For many liquids this is far because of their characteristic vapor pressure curves and due to the usual suction pressures at atmospheric pressure ensured. In the case of more volatile liquids, especially so-called cryogenic fluids, such as nitrogen, hydrogen, oxygen, etc. in liquid form, pumping very soon leads to those pressure ranges where gas bubbles inevitably arise because the vapor pressure falls below. It must therefore be ensured that there is always a sufficient pressure difference between the current pressure of the fluid to be pumped and its vapor pressure. One speaks in technical jargon of "Net Positive Suction Head (NPSH)", precisely this pressure difference on the inlet side of the pump. The required size of the "Net Positive Suction Head (NPSH)" depends on the size, type and design of the pump and is usually indicated on the pump. If a cryogenic fluid is to be pumped out of an atmospheric tank, this size of the NPSH determines how high the tank must be arranged opposite the pump in order to avoid cavities within the pumped fluid.
In plant engineering, of course, fulfilling this requirement is associated with additional effort, since a tank cannot be placed anywhere on the floor, but usually has to be made of special steel structures be built up. Especially with tanks with a volume of a few thousand liters, this is of course associated with considerable additional costs. For reasons of space, a tank of this type often has to be set up relatively far away from the feed pump. This in turn requires an extremely good and correspondingly expensive insulation of the supply line, since otherwise large cold losses occur due to heat absorption. The liquid in the tank anyway absorbs a certain amount of heat during storage, which means that liquid evaporates and the pressure in the tank would increase if it were not atmospheric, i.e. connected to the atmosphere via a valve. On the other hand, it would be far too expensive to build tanks of this size as pressure tanks. For transport purposes, however, cryogenic fluids are filled in pressure tanks in order to avoid the losses already mentioned as far as possible. Pumping out atmospheric tanks with cryogenic liquid content is therefore essential if you want to fill up a pressure tank. For example, the tanks on a truck for transporting such cryogenic fluids are kept at a pressure of about 3 bar. Such a tank is of course also refilled under pressure, so that the fluid basically has to be pumped from a location of lower pressure to a location of higher pressure. The lower the liquid level in the atmospheric tank, the greater the pressure difference.
Pumps for such purposes have an impeller, which is usually preceded by a pump inlet ring, called an inducer in the international technical language. This pump inlet ring is intended to slightly compress the fluid immediately in front of the pump impeller, i.e. to increase the NPSH. Conventional pump inlet rings or inducers are usually built similar to an Archimedes screw. They have a central pipe section as an axis of rotation, on the periphery of which one or more screw blades wind around the pipe section in a serpentine fashion. The pipe section is provided with a flow-optimized cap on the inlet side.
Practice shows that gas bubbles built in such a way form gas bubbles even at relatively low speeds. This fact has to do with the fluid flow forced by the pump inlet ring. First, the fluid becomes significant changes in direction as it enters the pump ring forced, which cause corresponding turbulence in the fluid. Turbulent flow also occurs at the edges of the airfoils, which result in local pressure drops under the vapor pressure of the fluid. In the limit range of the permissible number of revolutions, gas bubbles form immediately, which cannot be eliminated again in the course of the fluid in such a conventional pump inlet ring. Once the fluid is enclosed by the screw blades in the axial direction and transported further, the volume of the conveying cores thus formed does not change, nor is the acceleration acting on the fluid changed therein. The gas bubbles can no longer be broken down and get into the pump impeller, where the cavity effects mentioned above occur.

Es ist daher die Aufgabe der vorliegenden Erfindung, einen Pumpeneinlaufkranz insbesondere für Pumpen von cryogenen Fluida zu schaffen, welcher die Nachteile der herkömmlichen Pumpeneinlaufkränze reduziert und deshalb eine höhere Effizienz mit höheren Verdichtungen bei ent­sprechend geringerer Gasblasenbildung aufweist.
Diese Aufgabe löst ein Pumpeneinlaufkranz, insbesondere für Pumpen von cryogenen Fluida, der sich dadurch aus­zeichnet, dass er im wesentlichen aus einem hohlzylin­drischen Formstück gebildet ist, das pumpenseitig auf einer Welle befestigbar ist, und dessen in axialer Richtung andere Seite in Lamellen mit einer Steigung aus­geformt ist, welche Lamellen endseitig in eine scharfe Kante auslaufen und gemeinsam einen Schwingkorb bilden, derart, dass bei Rotation des Pumpeneinlaufkranzes Flüssigkeit auf der Einlaufseite des Pumpeneinlaufkranzes von den Lamellenenden erfassbar und zwischen den Lamellen hindurch axial nach hinten und radial nach aussen hin förderbar ist.
It is therefore the object of the present invention to provide a pump inlet ring, in particular for pumps of cryogenic fluids, which reduces the disadvantages of the conventional pump inlet rings and therefore has a higher efficiency with higher compressions with a correspondingly lower formation of gas bubbles.
This task is solved by a pump inlet ring, in particular for pumps of cryogenic fluids, which is characterized in that it is essentially formed from a hollow cylindrical fitting which can be attached to a shaft on the pump side, and the other side of which is formed in the axial direction in lamellae with a slope, which lamellae end in one run out sharp edge and jointly form a swing basket, such that when the pump inlet ring rotates, liquid on the inlet side of the pump inlet ring can be detected by the lamella ends and can be conveyed axially backwards and radially outwards between the lamellae.

In den Zeichnungen sind beispielsweise Ausführungen des erfindungsgemässen Pumpeneinlaufkranzes dargestellt und anhand der nachfolgenden Beschreibung im einzelnen erläutert.In the drawings, for example, designs of the pump inlet ring according to the invention are shown and explained in detail using the following description.

Es zeigt:

  • Figur 1 Einen Pumpeneinlaufkranz in perspektivischer Ansicht;
  • Figur 2 den Pumpeneinlaufkranz von Figur 1 mehr von der Einlaufseite her gesehen;
  • Figur 3 den Pumpeneinlaufkranz in Einbaulage einem Pumpenlaufrad vorgeschaltet, schematisch im Querschnitt;
  • Figur 4 einen Pumpeneinlaufkranz in Seitenansicht mit konkav geformten Lamellen-Förderflächen und
  • Figur 5 einen Pumpeneinlaufkranz andeutungsweise mit einer verwundenen Lamellen-Förderfläche.
It shows:
  • Figure 1 is a pump inlet collar in perspective view;
  • Figure 2 shows the pump inlet ring of Figure 1 more of the Seen inlet side;
  • FIG. 3 shows the pump inlet ring upstream of a pump impeller, schematically in cross section;
  • Figure 4 shows a pump inlet ring in side view with concave-shaped lamella conveying surfaces and
  • Figure 5 shows a pump inlet ring with a twisted lamella conveying surface.

Die erfindungswesentlichen Merkmale des Pumpeneinlauf­kranzes sind in der Figur 1 ersichtlich. Im wesentlichen ist er aus einem hohlzylindrischen Formstück 1 gebildet. Die Wandung des Hohlzylinders macht hier etwa einen Viertel des Aussendurchmessers aus. Dieses Grössenver­hältnis kann jedoch in beiden Richtungen variieren. In diesem Hohlzylinder 1 sind Ausnehmungen vorhanden, sodass schraubenlinienförmig verlaufende Lamellen 2 gebildet sind, die eine entsprechende Steigung aufweisen. Die optimale Steigung und Betriebs-Drehzahl wird vom zu pumpenden Fluid beeinflusst und variiert entsprechend.The features of the pump inlet ring essential to the invention can be seen in FIG. 1. It is essentially formed from a hollow cylindrical shaped piece 1. The wall of the hollow cylinder makes up about a quarter of the outside diameter. However, this size ratio can vary in both directions. Recesses are present in this hollow cylinder 1, so that helically extending lamellae 2 are formed which have a corresponding slope. The optimal gradient and operating speed is influenced by the fluid to be pumped and varies accordingly.

Die einzelnen Lamellen 2 sind zueinander identisch und wurzeln alle in der Wandung des Hohlzylinders 1. Ihre Enden 6 laufen in scharfe Kanten 3 aus, die dazu bestimmt sind, die ankommende Flüssigkeit gewissermassen "abzu­schneiden". Es versteht sich, dass die einzelnen Lamellen 2 in Laufrichtung des Pumpeneinlaufkranzes gesehen eine gewisse Dicke aufweisen müssen, um deren Stabilität im Betrieb zu gewährleisten. Pumpenseitig 7 ist das hohlzy­lindrische Formstück 1 verjüngt und läuft in eine Lager­büchse 12 aus, mittels welcher der Pumpeneinlaufkranz 1 auf einer Welle befestigbar ist. Die Lagerbüchse 12 kann zu diesem Zweck einen bedeutend kleineren Innendurch­messer als jener des Hohlzylinders 1 aufweisen, welcher zu diesem Zweck mit beidseits unterschiedlichen Innen­durchmessern hergestellt wird. Die Verjüngung an der Aussenseite des Hohlzylinders 1 beginnt noch vom Bereich der Lamellen 2 an, sodass jene in die Verjüngung hinein­reichen und in dieser wurzeln. Die Lamellenwurzeln 14 werden dadurch etwas weniger breit als die eigentlichen Lamellen, dafür werden durch die Ausnehmungen zwischen den Lamellen 2 Durchgänge geschaffen, durch welche die Flüssigkeit axial aus dem Pumpeneinlaufkranz 1 austreten kann. Zur Aufnahme der Flieh- und Raktionskräfte beim Pumpbetrieb, wenn der Pumpeneinlaufkranz 1 rotiert, sowie zu Dichtungszwecken, sind die Lamellen 2 im Bereich ihrer Enden 6 in ihrer Gesamtheit an ihrer Peripherie von einem Ringkranz 8 umfasst. Die Aussenseite 9 des Ringkranzes 8 ist bündig mit der Aussenseite 10 des Hohlzylinders 1. Durch die Rillen 11 in der Aussenseite 9 des Ringkranzes 8 ist eine Labyrinthdichtung gebildet, deren Bedeutung später klar wird. Der einlaufseitige Rand 15 des Ring­kranzes 8 kann in der gleichen Ebene liegen wie die Enden 6 der Lamellen 2, beziehungsweise deren Randkanten 3. In Figur 2 ist der gleiche Pumpeneinlaufkranz 1 im wesentlichen von der Einlaufseite her gesehen gezeigt. Hier ist der Verlauf der einzelnen Lamellen 2 erkennbar, die je schraubenlinienförmig mit einer gewissen Steigung gegen ihre Wurzeln 14 hin verlaufen. Die Enden 6 der Lamellen 2 sind derart gestaltet, dass sie je in eine scharfe Kante 3 auslaufen. Die Richtungen, in der diese Kanten 3 verlaufen, können ebenfalls variieren. Wenn diese nicht radial verlaufen, wird ein besserer "Schneid­effekt" erzielt. Zu diesem Zweck können die Kanten 3 von der Radialen aus in beiden Richtungen verdreht sein. In natürlicher Weise werden diese Richtungen mitbestimmt von der Steigung der Lamellen-Förderflächen 13 in der radia­ len Richtung im Bereich der Lamellenenden 6. Der Ring­kranz 8, welcher hier als Labyrinthdichtung ausgebildet ist, weist ein Innengewinde 16 auf, mittels dessen er über die Enden 6 der Lamellen 2 aufschraubbar und somit auswechselbar ist. In der Lagerbüchse 12 sind in axialer Richtung Nuten 17 ausgenommen, die dazu bestimmt sind, die Drehmomente von der Pumpenwelle auf den Pumpenein­laufkranz 1 zu übertragen.
Wie der erfindungsgemässe Pumpeneinlaufkranz 1 eingebaut wird, zeigt Figur 3 anhand eines Querschnittes einer jedoch nur teilweise dargestellten entsprechenden Pumpe für cryogene Fluida. Der Pumpeneinlaufkranz 1 ist mit seiner Lagerbüchse 12 auf die Pumpenwelle 18 aufgesteckt und dreht daher mit gleicher Drehzahl wie das eigentliche Pumpenlaufrad 19. Es ist jedoch auch denkbar, den Pumpen­einlaufkranz 1 mit einer separaten Welle anzutreiben, sodass auch andere Betriebsdrehzahlen als jene des Pumpenlaufrades 19 möglich sind. Mit seinem Ringkranz 8 ist der Pumpeneinlaufkranz 1 in einem Umlenker 20, in der internationalen Fachsprache Diffuser genannt, dichtend gelagert. Die Abdichtung des Raumes im Bereich des Ein­laufes des Pumpeneinlaufkranzes 1 vom Raum zwischen dem Bereich, wo das Fluid aus dem Pumpeneinlaufkranz 1 aus­ tritt, ist erforderlich, damit das verdichtete Fluid nicht aussen um den Pumpeneinlaufkranz 1 herum wieder zurück vor jenen rinnt. Der Umlenker 20 selbst ist auf seiner Innenseite 21 so gestaltet, dass an ihr schrauben­linienförmig verlaufende Lamellen angeformt sind. Die Steigung dieser Umlenkerlamellen ist jedoch gerade umge­kehrt zu jener der Inducer-Lamellen 2. Infolge der Rota­tion des Pumpeneinlaufkranzes 1 wird dem Fluid unweiger­lich eine Zirkulation um die Pumpenachse mitgegeben. Die erwähnte Umkehrung der Steigung der Umlenkerlamellen sorgt dafür, dass die Bewegungsrichtung des Fluids in die bezüglich der Pumpenachse axiale Richtung umgelenkt wird. Das vor dem Pumpeneinlaufkranz 1 ankommende Fluid wird also von den wie Schaufeln ausgebildeten Enden 6 der Lamellen 2 gewissermassen schneidend erfasst. Die von den Lamellenenden 6 erfasst Flüssigkeit wird dann längs der Lamellen-Förderflächen 13 in axialer Richtung nach hinten und zusätzlich wegen der Rotation und der daraus resul­tierenden Zentrifugalkraft radial nach aussen hin geför­dert. Es ist die Zentrifugalkraft, welche das Fluid nach aussen zur Innenwand des Umlenkers 20 hin beschleunigt, sodass bei entsprechender Wahl der Drehzahl das Fluid nicht nur gefördert, sondern vor allem auch verdichtet wird. Der Vorteil des erfindungsgemässen Pumpeneinlauf­kranzes 1 ist zum grössten Teil darin zu sehen, dass die Drehachse beim Einlauf frei ist. Nichts stellt sich hier dem ankommenden Fluid in den Weg und dieses wird demnach auch nicht zu abrupten Richtungsänderungen gezwungen, was turbulente Strömungen verursachen würde. Zusätzlich werden auch gewisse Gefahrenmomente eliminiert. Bei her­kömmlichen Pumpeneinlaufkränzen können grössere mecha­nische Partikel, welche möglicherweise im Fluid mitge­schwemmt werden, voll zwischen die fördernden Schaufeln gelangen und dort verklemmen. In einem solchen Fall wird sofort viel Reibungswärme erzeugt. Es entsteht Gas und eine erhebliche Explosionsgefahr ist unvermeidlich. Bei Fluida wie zum Beispiel Sauerstoff oder Wasserstoff fällt dabei ein beträchtliches Gefahrenpotential an. Durch die Wucht einer allfälligen Explosion kann die Pumpe zerris­sen werden. Beim erfindungsgemässen Pumpeneinlaufkranz 1 bilden die Lamellen 2 einen Schwingkorb, der gewisser­massen ein Sieb für allfällig angeschweimnte Partikel dar­stellt. Bei besonders gefährlichen Fluida kann ausserdem ins Innere des Pumpeneinlaufkranzes 1 ein eigentliches becherartiges Sieb aus einem Drahtgitter eingesetzt sein. Dieses Sieb kann direkt mit der Schraube, welche den Pumpeneinlaufkranz 1 auf der Pumpenwelle festhält, verklemmt sein. Der Rand des becherförmigen Siebes kann über die Enden 6 der Lamellen 2, das heisst über ihre Kanten 3 gezogen sein und bündig an den Ringkranz 8 anschliessen. In einer anderen Ausführung kann der Rand aber auch nur bis zum Beginn der Lamellenenden 6 gezogen sein, sodass deren Kanten 3 frei bleiben, um den "Schneideffekt" nicht zu beeinträchtigen. Das Partikel bleibt somit stets im Innern des Pumpeneinlaufkranzes 1 gefangen und kann keine mechanische Reibungswärme erzeugen. Durch die Rotation wird beim erfindungsgemässen Pumpeneinlaufkranz 1 eine stetige Verdichtung des Fluids während der Förderung erzielt, sodass die Gasblasen­bildung im Vergleich zu herkömmlichen Inducern bis zu höheren Dichtedifferenzen zwischen dem Einlauf- und Austrittsbereich vermieden wird. Allfällig sich trotzdem bildende Kavitäten werden zuerst im Bereich der Drehachse im Innern des Pumpeneinlaufkranzes 1 anfallen, wo sie die Wirkung des Inducers 1 nicht negativ beeinflussen. Nach dem Austritt aus dem Inducer 1 gelangt das Fluid verdichtet in den Umlenker oder Diffuser 20 und wir von dort direkt ins Innere des Pumpenlaufrades 19 weiter­gefördert. Der Wirkungsgrad des vorliegenden Pumpen­ einlaufkranzes 1 kann durch die spezielle Ausgestaltung der Lamellen 2 entscheidend beeinflusst werden. Neben der Grösse, den Grössenverhältnissen der Innen- und Aussendurchmesser des Hohlzylinders 1 des Pumpeneinlauf­kranzes 1 sind dessen Länge, die Anzahl der Lamellen 2 sowie deren Dicke und Steigung für die Verdichtungs­leistung von Bedeutung. Im besonderen aber hat auch die Ausgestaltung der einzelnen Lamellen 2, vorallem deren Lamellen-Förderflächen 13, Einfluss auf die Verdichtungs­leistung. Auch die Gestaltung der Lamellenenden 6 und der Verlauf von deren Randkanten 3 bestimmt, wieviel Flüssigkeit pro Umdrehung bei einem gegebenen Druck erfasst werden kann.
Um eine stetige Beschleunigung der von den Lamellenenden 6 ergriffenen Flüssigkeit zu gewährleisten, können die Lamellen-Förderflächen 13 konkav gekrümmt sein, wie dies in Figur 4 in einer Seitenansicht eines erfindungsgemäs­sen Pumpeneinlaufkranzes 1 gezeigt ist. Die Krümmung ist hierbei mit Vorteil so gestaltet, dass der Krümmungs­radius nach hinten gegen die Lamellenwurzeln 14 hin stetig abnimmt. Der Pumpeneinlaufkranz 1 hat durch diese Formgebung der Lamellen-Förderflächen 6 noch vermehrt den Charakter eines Schleuderkorbes 4. Die Flüssigkeit wird nicht nur mit einer gleichförmigen Beschleunigung gefördert, sondern einerseits durch die Zentrifugalkraft infolge der Rotation des Pumpeneinlaufkranzes 1 gegen aussen hin beschleunigt und gleichzeitig bewirkt die konkave, parabelförmige Krümmung der Lamellen-Förderflächen 13 aufgrund der Massenträgheit der Flüssigkeit eine etwa gleichförmige Beschleunigung der Flüssigkeit axial nach hinten. Beide Wirkungen tragen zur Verdichtung des Fluides gegen den Austritt aus dem Pumpeneinlaufkranz hin zu.
Figur 5 schliesslich zeigt in einem Teilschnitt andeu­tungsweise eine Lamelle 2, welche nicht nur parabelförmig gekrümmt ist, sondern deren Lamellen-Förderfläche 13 zu­sätzlich auch eine Verwindung aufweist. Die Fläche 13 ist in Richtung gegen die Lamellenwurzel 14 hin allmählich gegen die Peripherie des Pumpeneinlaufkranzes 1 hin ver­dreht. Dadurch wird ein Ausleeren beziehungsweise Aus­werfen der geförderten Flüssigkeit in radialer Richtung begünstigt, was natürlich ebenfalls geeignet ist, den Verdichtungseffekt gegen aussen hin zu steigern.
In der Praxis wird der erfindungsgemässe Pumpeneinlauf­kranz 1 vorteilhaft gegossen. In Messversuchen wurde ein solcher Pumpeneinlaufkranz 1 vor das Pumpenlaufrad einer cryogenen Pumpe vorgeschaltet, mit welcher dann flüssiger Stickstoff aus einem atmosphärischen Tank bei einer Temperatur von -195,8 Grad C abgepumpt wurde. Unmittelbar beim Pumpeneinlauf wurde eine Temperatur von -186,7 Grad C gemessen, was einem NPSH von Null entspricht. Der korrespondierende Dampfdruck beträgt dort 2,55 bar. Die Pumpe konnte ohne Probleme gestartet werden und kam sofort auf Druck, das heisst, zwischen dem Pumpeneinlauf­kranz 1 und dem Pumpenlaufrad 19 wurde dank dem Pumpeneinlaufkranz 1 genügend Druck aufgebaut, dass die Flüssigkeit vor dem Pumpenlaufrad 19 einen Druck aufwies, der über der Dampfdruckkurve lag. Kavitation wurde keine festgestellt.
Durch die Verwendung von erfindungsgemässen Inducern können cryogene Flüssigkeiten jetzt aus atmosphärischen Tanks abgepumpt werden, wobei ein ausreichender "Net Positiv Suction Head NPSH" gewährleistet ist. Ent­sprechende Lagertanks können deshalb kostengünstiger auf Bodenhöhe stehen und daher in vielen Fällen auch viel näher bei der Pumpe, beziehungsweise dort, wo das cryo­gene Fluid abzunehmen gewünscht wird. Das aber bringt auch eine Reduktion der Wärmeabsorbtion, da die cryogenen Leitungen kürzer werden und teure Isolationen werden weniger umfangreich.
The individual lamellae 2 are identical to one another and are all rooted in the wall of the hollow cylinder 1. Their ends 6 end in sharp edges 3, which are intended to "cut off" the incoming liquid to a certain extent. It goes without saying that the individual lamellae 2 must have a certain thickness when viewed in the running direction of the pump inlet ring in order to ensure their stability during operation. On the pump side 7, the hollow cylindrical shaped piece 1 is tapered and ends in a bearing bush 12, by means of which the pump inlet ring 1 can be fastened on a shaft. For this purpose, the bearing bush 12 can have a significantly smaller inner diameter than that of the hollow cylinder 1, which for this purpose is produced with different inner diameters on both sides. The taper on the outside of the hollow cylinder 1 begins from the area of the lamellae 2, so that they extend into the taper and are rooted in it. The lamella roots 14 are thus a little less wide than the actual lamellae, but the passages are created through the recesses between the lamellae 2, through which the liquid can exit axially from the pump inlet ring 1. To absorb the centrifugal and rocking forces at Pumping operation when the pump inlet ring 1 rotates, as well as for sealing purposes, the fins 2 in the area of their ends 6 are encompassed in their entirety by an annular ring 8 on their periphery. The outside 9 of the ring rim 8 is flush with the outside 10 of the hollow cylinder 1. A labyrinth seal is formed by the grooves 11 in the outside 9 of the ring rim 8, the meaning of which will become clear later. The inlet-side edge 15 of the ring rim 8 can lie in the same plane as the ends 6 of the lamellae 2, or their edge edges 3. In FIG. 2, the same pump inlet rim 1 is shown essentially seen from the inlet side. The course of the individual lamellae 2 can be seen here, each of which extends helically with a certain slope towards its roots 14. The ends 6 of the slats 2 are designed such that they each end in a sharp edge 3. The directions in which these edges 3 run can also vary. If these are not radial, a better "cutting effect" is achieved. For this purpose, the edges 3 can be twisted in both directions from the radial. These directions are naturally determined by the gradient of the lamella conveying surfaces 13 in the radia len direction in the area of the lamella ends 6. The ring rim 8, which is designed here as a labyrinth seal, has an internal thread 16, by means of which it can be screwed onto the ends 6 of the lamellae 2 and can therefore be replaced. In the bearing bush 12 grooves 17 are recessed in the axial direction, which are intended to transmit the torques from the pump shaft to the pump inlet ring 1.
FIG. 3 shows how the pump inlet ring 1 according to the invention is installed on the basis of a cross section of a corresponding pump for cryogenic fluids, which is however only partially shown. The pump inlet ring 1 is attached with its bearing bush 12 to the pump shaft 18 and therefore rotates at the same speed as the actual pump impeller 19. However, it is also conceivable to drive the pump inlet ring 1 with a separate shaft, so that operating speeds other than those of the pump impeller 19 are also possible are. With its ring rim 8, the pump inlet rim 1 is sealed in a deflector 20, called diffuser in the international technical language. The sealing of the space in the area of the inlet of the pump inlet ring 1 from the space between the area where the fluid from the pump inlet ring 1 occurs, is necessary so that the compressed fluid does not run around the outside of the pump inlet ring 1 back again. The deflector 20 itself is designed on its inside 21 in such a way that lamellae which extend helically are formed on it. However, the slope of these deflector plates is exactly the opposite of that of the inducer plates 2. As a result of the rotation of the pump inlet ring 1, the fluid is inevitably given a circulation about the pump axis. The aforementioned reversal of the slope of the deflector plates ensures that the direction of movement of the fluid is deflected in the axial direction with respect to the pump axis. The fluid arriving in front of the pump inlet ring 1 is thus, as it were, cut by the ends 6 of the lamellae 2, which are designed as blades. The liquid captured by the slat ends 6 is then conveyed radially outward along the slat conveying surfaces 13 in the axial direction and additionally because of the rotation and the resulting centrifugal force. It is the centrifugal force that accelerates the fluid outwards towards the inner wall of the deflector 20, so that with a corresponding choice of the speed, the fluid is not only conveyed, but above all also compressed becomes. The advantage of the pump inlet collar 1 according to the invention can largely be seen in the fact that the axis of rotation is free at the inlet. Nothing stands in the way of the incoming fluid and therefore it is not forced to make abrupt changes in direction, which would cause turbulent flows. In addition, certain moments of danger are eliminated. With conventional pump inlet rings, larger mechanical particles, which may be swept up in the fluid, can get fully between the conveying blades and jam there. In such a case, a lot of frictional heat is immediately generated. Gas is generated and a considerable risk of explosion is inevitable. With fluids such as oxygen or hydrogen, there is a considerable risk potential. The force of a possible explosion can tear the pump apart. In the case of the pump inlet ring 1 according to the invention, the lamellae 2 form an oscillating basket, which to a certain extent represents a sieve for any particles that are washed up. In the case of particularly dangerous fluids, an actual cup-like sieve made of a wire mesh can also be inserted inside the pump inlet ring 1. This sieve can be screwed directly to the screw Pump ring 1 holds firmly on the pump shaft, be jammed. The edge of the cup-shaped sieve can be drawn over the ends 6 of the lamellae 2, that is to say over its edges 3, and connect flush to the ring rim 8. In another embodiment, the edge can also only be drawn to the beginning of the slat ends 6, so that its edges 3 remain free so as not to impair the "cutting effect". The particle therefore always remains trapped inside the pump inlet ring 1 and cannot generate any mechanical frictional heat. Due to the rotation, a constant compression of the fluid is achieved during the pumping of the inventive pump inlet ring 1, so that the formation of gas bubbles compared to conventional inducers up to higher density differences between the inlet and outlet area is avoided. Any cavities that nevertheless form will first occur in the area of the axis of rotation in the interior of the pump inlet ring 1, where they do not negatively influence the action of the inducer 1. After exiting the inducer 1, the fluid reaches the deflector or diffuser 20 in compressed form and from there it is conveyed directly into the interior of the pump impeller 19. The efficiency of the present pumps Inlet ring 1 can be decisively influenced by the special design of the slats 2. In addition to the size, the size ratios of the inside and outside diameter of the hollow cylinder 1 of the pump inlet ring 1, its length, the number of fins 2 and their thickness and pitch are important for the compression performance. In particular, however, the design of the individual lamellae 2, especially their lamella conveying surfaces 13, also has an influence on the compression performance. The design of the lamella ends 6 and the course of their peripheral edges 3 also determine how much liquid can be detected per revolution at a given pressure.
In order to ensure a constant acceleration of the liquid seized by the fin ends 6, the fin conveying surfaces 13 can be concavely curved, as is shown in FIG. 4 in a side view of a pump inlet ring 1 according to the invention. The curvature is advantageously designed in such a way that the radius of curvature decreases continuously towards the back against the lamella roots 14. Due to this shape of the lamella conveying surfaces 6, the pump inlet ring 1 has the character of a centrifugal basket 4. The liquid becomes not only conveyed with a uniform acceleration, but on the one hand accelerated towards the outside by the centrifugal force as a result of the rotation of the pump inlet ring 1 and, at the same time, the concave, parabolic curvature of the lamella conveying surfaces 13 causes an approximately uniform acceleration of the liquid axially to the rear due to the inertia of the liquid . Both effects contribute to the compression of the fluid against the discharge from the pump inlet ring.
Finally, FIG. 5 shows a partial section of a lamella 2, which is not only curved in a parabolic shape, but whose lamella conveying surface 13 also has a twist. The surface 13 is gradually rotated towards the lamella root 14 towards the periphery of the pump inlet ring 1. This promotes emptying or ejection of the liquid conveyed in the radial direction, which is of course also suitable for increasing the compression effect towards the outside.
In practice, the pump inlet ring 1 according to the invention is advantageously cast. In measurement tests, such a pump inlet ring 1 was placed in front of the pump impeller upstream cryogenic pump, with which liquid nitrogen was then pumped out of an atmospheric tank at a temperature of -195.8 degrees C. A temperature of -186.7 degrees C was measured immediately at the pump inlet, which corresponds to an NPSH of zero. The corresponding vapor pressure there is 2.55 bar. The pump could be started without problems and came immediately to pressure, that is, between pump inlet ring 1 and pump impeller 19, thanks to pump inlet ring 1, sufficient pressure was built up that the liquid in front of pump impeller 19 had a pressure that was above the vapor pressure curve. No cavitation was found.
By using inducers according to the invention, cryogenic liquids can now be pumped out of atmospheric tanks, with an adequate "net positive suction head NPSH" being guaranteed. Corresponding storage tanks can therefore stand at ground level more cost-effectively and therefore in many cases also much closer to the pump or wherever the cryogenic fluid is desired to be removed. However, this also brings about a reduction in heat absorption, since the cryogenic lines become shorter and expensive insulation becomes less extensive.

Selbstverständlich können erfindungsgemässe Pumpenein­laufkränze für linksdrehende oder rechtsdrehende Pumpen hergestellt und eingesetzt werden.Of course, pump inlet rings according to the invention can be manufactured and used for left-hand or right-hand pumps.

Claims (10)

1. Pumpeneinlaufkranz, insbesondere für Pumpen von cryo­genen Fluida, dadurch gekennzeichnet, dass er im we­sentlichen aus einem hohlzylindrischen Formstück (1) gebildet ist, das pumpenseitig (7) auf einer Welle (18) befestigbar ist und dessen in axialer Richtung andere Seite in Lamellen (2) mit einer Steigung aus­geformt ist, welche Lamellen (2) endseitig (6) je in eine scharfe Kante (3) auslaufen und gemeinsam einen Schwingkorb (4) bilden, derart, dass bei Rotation des Pumpeneinlaufkranzes (1) Flüssigkeit auf der Einlauf­seite (5) des Pumpeneinlaufkranzes (1) von den Lamel­lenenden (6) erfassbar und zwischen den Lamellen (2) hindurch axial nach hinten und radial nach aussen hin förderbar ist.1. Pump inlet ring, in particular for pumps of cryogenic fluids, characterized in that it is essentially formed from a hollow cylindrical shaped piece (1) which can be fastened on the pump side (7) to a shaft (18) and whose other side in the axial direction in lamellae (2) is formed with a slope, which lamellae (2) end (6) each end in a sharp edge (3) and together form a swing basket (4), such that when the pump inlet ring (1) rotates, liquid on the inlet side (5) of the pump inlet ring (1) can be grasped by the plate ends (6) and can be conveyed axially backwards and radially outwards between the plates (2). 2. Pumpeneinlaufkranz nach Anspruch 1, dadurch gekenn­zeichnet, dass die Gesamtheit der Lamellen (2) im Bereich ihrer Enden (6) an ihrer Peripherie von einem Ringkranz (8) umfasst werden, dessen Aussenseite (9) bündig mit der Aussenseite (10) der Lamellen (2) ist und gegen aussen hin mittels Rillen (11) als Laby­rinthdichtung ausgebildet ist.2. Pump inlet ring according to claim 1, characterized in that the entirety of the lamellae (2) in the region of their ends (6) at their periphery are encompassed by an annular ring (8), the outside (9) of which is flush with the outside (10) Slats (2) and is formed towards the outside by means of grooves (11) as a labyrinth seal. 3. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass der Pumpenein­laufkranz in axialer Richtung von den Lamellenenden (6) her noch vom Bereich der Lamellen an beginnend verjüngt ist, und dass die Verjüngung endseitig in eine Lagerbüchse (12) mit kleinerem Innendurchmesser als der Hohlzylinder ausläuft.3. Pump inlet ring according to one of the preceding claims, characterized in that the pump inlet ring is tapered in the axial direction from the plate ends (6) from the area of the plates, and that the taper ends in a bearing bush (12) with a smaller inner diameter than the hollow cylinder runs out. 4. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass die laufrich­tungsseitigen Lamellen-Förderflächen (13) je von der Lamellenwurzel (14) zum Lamellenende (6) hin konkav geformt sind.4. Pump inlet ring according to one of the preceding claims, characterized in that the direction-side lamella conveying surfaces (13) are each formed from the lamella root (14) to the lamella end (6) concave. 5. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass die laufrich­tungsseitigen Lamellen-Förderflächen (13) je vom Lamellenende (6) her gegen die Lamellenwurzel (14) hin gegen die Peripherie des Pumpeneinlaufkranzes (1) hin verwunden sind.5. Pump inlet ring according to one of the preceding claims, characterized in that the direction-side lamella conveying surfaces (13) depending on the lamella end (6) against the lamella root (14) towards the periphery of the pump inlet ring (1) are twisted. 6. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass die Lamellenen­den (6) als Schaufeln ausgeformt sind, deren Ränder in scharfe Kanten (3) auslaufen.6. Pump inlet ring according to one of the preceding claims, characterized in that the lamella ends (6) are shaped as blades, the edges of which end in sharp edges (3). 7. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass die den Rand der Lamellenenden (6) bildenden Kanten (3) in einer radialen Ebene zum Pumpeneinlaufkranz (1) liegen.7. Pump inlet ring according to one of the preceding claims, characterized in that the edges (3) forming the edge of the lamella ends (6) lie in a radial plane to the pump inlet ring (1). 8. Pumpeneinlaufkranz nach einem der Ansprüche 2 bis 7, dadurch gekennzeichnet, dass der einlaufseitige Rand (15) des Ringkranzes (8) in derselben Ebene liegt wie die endseitigen Ränder (3) der Lamellenenden (6).8. Pump inlet ring according to one of claims 2 to 7, characterized in that the inlet-side edge (15) of the ring rim (8) lies in the same plane as the end edges (3) of the fin ends (6). 9. Pumpeneinlaufkranz nach einem der vorgenannten An­sprüche, dadurch gekennzeichnet, dass die laufrich­tungsseitigen Lamellen-Förderflächen (13) im Quer­schnitt quer zu dem Lamellen (2) konkav gekrümmt sind.9. Pump inlet ring according to one of the preceding claims, characterized in that the direction-side lamella conveying surfaces (13) are concavely curved in cross-section transverse to the lamellae (2). 10. Verwendung von Pumpeneinlaufkränzen nach einem der vorgenannten Ansprüche zum Verdichten eines cryoge­ nen Fluides vor dem Eintritt in ein Pumpeneinlaufrad einer cryogenen Pumpe.10. Use of pump inlet rings according to one of the preceding claims for compressing a cryogenic fluid before entering a pump impeller of a cryogenic pump.
EP19870810695 1987-11-26 1987-11-26 Centrifugal pump for cryogenic fluids Expired - Lifetime EP0317687B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE8787810695T DE3776570D1 (en) 1987-11-26 1987-11-26 CENTRIFUGAL PUMP FOR CRYOGENE FLUIDA.
EP19870810695 EP0317687B1 (en) 1987-11-26 1987-11-26 Centrifugal pump for cryogenic fluids

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19870810695 EP0317687B1 (en) 1987-11-26 1987-11-26 Centrifugal pump for cryogenic fluids

Publications (2)

Publication Number Publication Date
EP0317687A1 true EP0317687A1 (en) 1989-05-31
EP0317687B1 EP0317687B1 (en) 1992-01-29

Family

ID=8198433

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870810695 Expired - Lifetime EP0317687B1 (en) 1987-11-26 1987-11-26 Centrifugal pump for cryogenic fluids

Country Status (2)

Country Link
EP (1) EP0317687B1 (en)
DE (1) DE3776570D1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5368438A (en) * 1993-06-28 1994-11-29 Baxter International Inc. Blood pump
US6461520B1 (en) 1999-05-21 2002-10-08 Life Spring Limited Partnership User-activated ultra-violet water treatment unit
CN105370618A (en) * 2015-11-16 2016-03-02 蔡少波 Tapered axial flow centrifugal compressor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102678935A (en) * 2012-04-27 2012-09-19 大连华阳光大密封有限公司 Pump ring used for mechanical seal

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE480863C (en) * 1924-10-08 1930-11-15 Hermann Foettinger Dr Ing Device to avoid cavitation in turbo pumps with the highest speed for dripping fluids
FR924306A (en) * 1946-03-21 1947-08-01 Vane pump forming a vapor separator and applicable in particular to airplanes
US2736266A (en) * 1956-02-28 eisele
US2857081A (en) * 1953-02-09 1958-10-21 Tait Mfg Co The Gas separating and pumping devices
US2984189A (en) * 1958-08-07 1961-05-16 Worthington Corp Inducer for a rotating pump
US3217654A (en) * 1963-08-08 1965-11-16 Springer Frederick Howard Combination screw and centrifugal submergible pump
US3323465A (en) * 1964-04-17 1967-06-06 Shell Oil Co Inlet piece for a centrifugal pump

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2736266A (en) * 1956-02-28 eisele
DE480863C (en) * 1924-10-08 1930-11-15 Hermann Foettinger Dr Ing Device to avoid cavitation in turbo pumps with the highest speed for dripping fluids
FR924306A (en) * 1946-03-21 1947-08-01 Vane pump forming a vapor separator and applicable in particular to airplanes
US2857081A (en) * 1953-02-09 1958-10-21 Tait Mfg Co The Gas separating and pumping devices
US2984189A (en) * 1958-08-07 1961-05-16 Worthington Corp Inducer for a rotating pump
US3217654A (en) * 1963-08-08 1965-11-16 Springer Frederick Howard Combination screw and centrifugal submergible pump
US3323465A (en) * 1964-04-17 1967-06-06 Shell Oil Co Inlet piece for a centrifugal pump

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5368438A (en) * 1993-06-28 1994-11-29 Baxter International Inc. Blood pump
WO1995000186A1 (en) * 1993-06-28 1995-01-05 Baxter International Inc. Blood pump
US5501574A (en) * 1993-06-28 1996-03-26 Baxter International Inc. Blood pump
US6461520B1 (en) 1999-05-21 2002-10-08 Life Spring Limited Partnership User-activated ultra-violet water treatment unit
CN105370618A (en) * 2015-11-16 2016-03-02 蔡少波 Tapered axial flow centrifugal compressor

Also Published As

Publication number Publication date
EP0317687B1 (en) 1992-01-29
DE3776570D1 (en) 1992-03-12

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