NZ201627A

NZ201627A - Multiple stage centrifugal pump with inlet sump

Info

Publication number: NZ201627A
Application number: NZ201627A
Authority: NZ
Inventors: W Lehmann
Original assignee: Sihi Gmbh & Co Kg
Priority date: 1981-09-11
Filing date: 1982-08-18
Publication date: 1985-04-30
Also published as: ES276130Y; DE3263132D1; ES276130U; ATE12814T1; DE3136116A1; EP0075100B2; ZA825936B; DK405282A; EP0075100B1; AU8750182A; NO822996L; EP0075100A1

Abstract

1. A multistage centrifugal pump with a vertical shaft and a segmental housing (2) comprising a plurality of housing sections, for feeding liquids near to their boiling point, which at its lower end (3) on the intake side is immersed in a container (1) for the inflow of the liquid, above which the pump drive and the pressure pipe connection (5) are accessible, characterized in that the housing section (6) of the second or a further pump stage has an annular flange (7) in the form of a cover of the container (1), on which the inlet connection (8) accessible above the container (1) is disposed.

Description

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NEW ZEALAND No.: Date: PATENTS ACT, 1953 COMPLETE SPECIFICATION 18AUG 1982 m MULTIPLE-STAGE CENTRIFUGAL PUMP ,^/We, SIHI GmbH & Co KG, a corporation under the laws of the Federal Republic of Germany, of Lindenstrape 17 0, 2210 Itzehoe, Federal Republic of Germany hereby declare the invention for which ^ / we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 201627 JA - a - Description The invention relates to a multiple-stage centrifugal pump, particularly for transporting liquids close to their "boiling point, which dips on the suction side into a sump for the inlet of the liquid.

As is known, the difficulties with pumps which are required to transport liquids close to their boiling points are always to have an adequate inlet head to the inlet side of the pump and as calm as possible a transported medium at the pump inlet, or to produce a pump with a correspondingly low NPSH (Net Positive Suction Head) value, so that no cavitation occurs on the pump inlet side and the known cavitation damage in the pump resulting therefrom does not occur, and a trouble-free transport is made possible. In order to improve the NTSH value of the pump and in order to calm the medium, measures such as the arrangement of a special rotor in the first stage for particularly low NESH values, and special configuration of the inlet are known.

If such measures prove inadequate, there remains as a final possibility a geodetically low arrangement of the pump in order to obtain the desired inlet conditions. If e.g. the transport is required to be made from a tank at ground level, then the pump unit is arranged in a sunk pit so as to create the necessary inlet head.

The underlying aim of the invention is to produce m x a centrifugal pump which renders the arrangement of the O pump unit in a pit unnecessary in many cases.

Y u> jaj ■.VI O f; S o?' The solution according to the invention is that a ^ xsy v> 201627 - ?> - ring flange for attachment to the sump is mounted on or forms part of the housing of the second or of a further pump stage.

The ring flange is preferably mounted on or forms part of the final or penultimate stage housing, so that the pump projects as deeply as possible into the sump. As a further development of the idea of the invention, the ring flange may itself form the cover of the sump. It is convenient to arrange the inlet pipe connection for the sump on the cover. Either the inlet pipe connection may be directly connected to the cover (e.g. welded), or an installation facility for the inlet pipe connection is provided on the cover.

Th^ advantage of this construction lies in the fact that the sump, with the part of the pump contained in it, can simply be lowered into a drilled earth hole and the lacking inlet head can thus be obtained. The excavation and securing of a pit to house the pump unit and the associated fittings is economised, because with the arrangement according to the invention the connections , the motor and the fittings can remain above ground. Pumps which have a housing of linked construction, namely particularly standard series pumps, are preferably suited for use in the context of the invention. This means that only a minimum outlay is necessary in order to produce the special pumps according to the invention if one starts from a series pump, namely the construction of a housing part as a ring flange or sump cover.

The effect of the invention depends on the one 201627 _ k ~ hand, on the fact that the pump inlet within the sump is placed at a low geodetic height, and on the other hand on the reducing of turbulence in the liquid in the sump. According to the invention the guidance of and reduction of turbulence in the liquid can "be further improved if hydrodynamic fins are arranged in the sump, being preferably directed away from the sump cover. The arrangement of hydrodynamic fins is particularly convenient if the pump is not arranged centrally in the sump. It is further convenient, in order to utilise the existing pressure head, to construct the point of issue of the inlet pipe connection into the sump in a diffuser-like or at least well-rounded manner.

According to a further feature of the invention, the interval between the pump inlet and the wall of the \ sump opposite the pump inlet should be at least equal to the diameter of the pump inlet.

The invention is explained more fully below with reference to the drawing, which illustrates an advantageous exemplary embodiment in a partly sectioned side elevation.

The sump 1, which may be imagined as a body of rotation with vertical axis, has a top aperture, which is closed by a cover 7- This cover carries the pump 2 with vertical axis, the cover being constructed as a housing part 6 of the third stage of four pump stages in all. This construction has the advantage that the pump is main- , N\ ©s £>\\ tained in the cover in an extremely simple manner, so that the ^..pump inlet 3 dips comparatively deeply into the sump.

O v- <§^/ Instead of the housing part of the third stage, that of the fourth stage 4 could also be constructed" as a sump cover if the flange of the pressure pipe connection, 5 allows sufficient space for this. The latter, like the motor and the motor coupling, is arranged above the cover 7 and hence above the ground into which the sump 1 is sunk, and hence freely accessible for assembly and maintenance.

The cover 7 contains, firmly attached, the inlet pipe bend 8, the connecting flange of which is likewise placed above the plane of the sump cover 7«The outlet orifice 9 of the pipe connection 8 is rounded in diffuser fashion in order to reduce the flow losses. In the vicinity of this outlet orifice - but also possibly in further regions of the sump 1 - hydrodynamic fins, one of which is indicated by chain-dotted lines at 11, may be provided in order to direct and reduce turbulence in the transported med If media having a high superatmospheric suction pressure are required to be transported, e.g. CC^i then an arrangement of the housing part used as the cover 7 as far as possible away from the inlet orifice 3 may also be recommended in order that the greatest possible number of pump stages is placed within the sump 1 and can therefore be dimensioned solely in relation to the, higher suction pressure instead of in relation to the atmospheric pressure.

Claims

201627 - 6 - WHAT %/WE CLAIM fS: Multiple-stage centrifugal pump for1-transporting;;a medium, particularly for transporting liquids close to their boiling points, which dips on the suction side into a sump for the inlet of the liquid, characterised in that a ring flange for the attachment of the sump thereto is mounted on or forms part of the housing of the second or of a further pump stage.
2. Multiple-stage centrifugal pump according to Claim 1, characterised in that the ring flange is mounted on or forms part of the final or penultimate stage housing part.
3. Multiple-stage centrifugal pump according to Claim 1 or 2, characterised in that the ring flange is constructed as the cover of the sump.
4. Multiple-stage centrifugal pump according to any of Claims 1 to 3, characterised in that the inlet pipe connection is arranged on the cover of the sump.
5. Multiple-stage centrifugal pump according to any of Claims 1 to 4, characterised in that the sump contains hydrodynamic f ins./ to direct and reduce turbulence in the transported medium
6. Multiple-stage centrifugal pump according to any of Claims 1 to 5, characterised in that the inlet into the sump is formed as a diffuser to reduce flow losses.
7. Multiple-stage centrifugal pump according to any ^ of Claims 1 to 6, characterised in that an interval ^which corresponds at least to the diameter of the pump //■inlet is present between the pump inlet and the 201627 - 7 - wall of the sump opposite the pump inlet.
8. Multiple-stage centrifugal pump, substantially as herein before described with reference to the accompanying drawing. uated this Yl day of A.J. PARK & SON per agents for the applicants