CA2051927C

CA2051927C - Vane apparatus for clog resistant pump

Info

Publication number: CA2051927C
Application number: CA 2051927
Authority: CA
Inventors: Ulf Arbeus
Original assignee: ITT Flygt AB
Current assignee: Xylem Water Solutions AB
Priority date: 1991-09-20
Filing date: 1991-09-20
Publication date: 1997-07-15
Anticipated expiration: 2011-09-20
Also published as: CA2051927A1

Abstract

The vanes (6) of a pump housing (5) are designed with strongly back swept leading edges (7) as seen in the direction of the flow, the vanes (6) being given a bulb form in the outward direction.

Description

Vane Ap~aratus for Cloq Resistant Pump Background of the Invention This inventlon relates to vane apparatus for clog resistant pumps. Such pumps may roughly be categorized as centrifugal pumps and axial pumps.

The centrifugal pump comprises an impeller consisting of a hub, at least one cover disc on said hub and a number of vanes, a so-called open impeller. A closed impeller is provided with two cover discs and intermediate vanes.
Common for the two types is that the liquid is sucked into the centre of the impeller in an axial direction and leaves it tangentially at the periphery.

The axial flow pump differs from the centrifugal pump in that the liquid leaves the pump in a substantially axial direction. This linking of the fluid is taken care of by a number of vanes in the pump housing after the impeller.
These vanes also normally serve as supporting elements in the housing construction.

When pumping sewage water and certain types of process water cont~ning elongated fibres, the pumping may be disturbed by raqs, fibres, etc., getting stuck to the front edges of the vanes on the impeller and in the pump housing. Such build-ups can initia~ly ~rea~ ~ib~a*ions in the pump, consequently the efficiency decreases and finally the pump might get totally clogged. One way to make the objects leave the vanes is to let the pump rotate backwards at certain intervals, but this is of course not an acceptable solution. Another way to diminish the clogging risk is to provide the pump with cutting means which divide the . ~ "" . . . . . . . ........... ~ .

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pollutlons lnto pleces before they are sucked lnto the lmpeller. An example of such a solutlon 18 shown ln the Swedlsh Patent No. 820 5774-6. A dlsadvantage wlth thls solutlon 18 that the cuttlng means may be qulckly worn out whlch mlght cause the clogglng problem to become even worse.
The purpose of thls lnventlon 18 to solve the clogglng problems mentloned above ln a totally new and dlfferent way. The solutlon 18 obtalned by help of the apparatus descrlbed hereln.
summarY of the Inventlon An ob~ect of the lnventlon 18 to provlde vane apparatus for a non-clogglng pump of centrlfugal or axlal flow type.
Accordlng to the lnventlon, there 18 provlded a pump of the axlal flow type for pumplng llquld contalnlng pollutants such as elongated flbres, whlch pump comprlses ln comblnatlonS a motor for drlvlng an lmpeller havlng an lmpeller hub wlth flrst vanes extendlng from sald hub, the motor havlng a houslng~ a plpe formed pump houslng surroundlng sald motor and flrst vanes and formlng an annular channel therebetween for conveylng the pumped llquld ln a rearward flow dlrectlon from sald hub; sald pump houslng belng supportedly attached to the houslng of the motor by means of a plurallty of addltlonal vanes, sald addltlonal vanes belng axlally dlsplaced and rearward of sald hub and sald flrst vanes; and each of sald addltlonal vanes belng formed wlth a leadlng edge swept rearward ln the dlrectlon of flow and a tralllng edge whlch 18 transverse to the dlrectlon of flow and ~, havlng a bulb portlon wlth lncreased thlckness ad~acent the pump houslng and wlth decreaslng thlckness toward the traillng edge of sald addltlonal vane.

- 2a -Brlef DescrlPtlon of the Drawlnas Other ob~ects and advantages of the lnventlon wlll be more fully apparent from the followlng descrlptlon, clalms and drawlngs ln whlchs Flg. 1 ls an axlal vlew of the vanes ln an axlal flow pump accordlng to the lnventlon; and Flg. 2 18 a merldlous cut taken along llnes A-A of Flg.
1.
Detalled DescrlPtlon of the Preferred Embodiment Referrlng to Flg. 1, there 18 lllustrated an lmpeller hub 1 provlded wlth flrst vanes 2, a motor unlt 3 havlng a houslng and an annular channel 4 deflned by a plpe formed pump houslng 5 surroundlng the motor 3. The pump houslng 5 ls supportedly attached to the houslng of the motor by means of addltlonal vanes 6 each havlng a leadlng edge. In operatlon, the rotatlng lmpeller vanes 2 suck the llquid through the annular channel 4. When the llquld has passed vanes 2 lt 18 llnked by the vanes 6 for obtalnlng pressure energy.
In order to dlmlnlsh the rlsk that flbres and the llke wlll clog on the leadlng edge 7 of the vane 6, the latter ls deslgned strongly swept backwards, as seen ln the dlrectlon of the flow, causlng the flbres to sllp outwards ln the dlrectlon of the wall 5 of the pump houslng where the veloclty ls the hlghest. In addltlon, the vane 6 ls deslgned wlth a bulb portlon 8 havlng lncreased thlckness towards the wall of houslng 5 and wlth decreaslng thlckness towards the tralllng edge of the vane 6. In thls way the flbres easlly sllp over the edge of the vane and the .

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bulb has only a sllght lnfluence on the flow as a whole. In order to prevent solld materlal from gettlng stuck ln the transltlon between leadlng edge 7 and the wall of houslng 5, sald part ls deslgned wlth a radlus and no sharp corners.
By help of the lnventlon ls obtalned a devlce whlch conslderably dlmlnlshes the rlsk for clogglng ln pumps operatlng with llqulds contalnlng flbres, rugs, etc.
Whlle the present lnventlon has been dlsclosed ln connectlon wlth a preferred embodlment thereof, the scope of the lnventlon ls deflned by the clalms.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A pump of the axial flow type for pumping liquid containing pollutants such as elongated fibres, which pump comprises in combination a motor for driving an impeller having an impeller hub with first vanes extending from said hub, the motor having a housing; a pipe formed pump housing surrounding said motor and first vanes and forming an annular channel therebetween for convoying the pumped liquid in a rearward flow direction from said hub; said pump housing being supportedly attached to the housing of the motor by means of a plurality of additional vanes, said additional vanes being axially displaced and rearward of said hub and said first vanes; and each of said additional vanes being formed with a leading edge swept rearward in the direction of flow and a trailing edge which 18 transverse to the direction of flow and having a bulb portion with increased thickness adjacent the pump housing and with decreasing thickness toward the trailing edge of said additional vane.