GB2413604A

GB2413604A - A seal construction for a centrifugal pump

Info

Publication number: GB2413604A
Application number: GB0508430A
Authority: GB
Inventors: Der Neut Cornelis Albert Van; Hasan Huseyin Bugdayci
Original assignee: IHC Holland NV
Current assignee: IHC Holland NV
Priority date: 2004-04-26
Filing date: 2005-04-26
Publication date: 2005-11-02
Anticipated expiration: 2025-04-26
Also published as: BE1016507A3; NL1026041C2; GB0508430D0; GB2413604B; DE102005019654A1

Abstract

A seal construction for sealing the impeller 2 of a centrifugal pump on the suction side 3 with respect to the pump housing 1 comprises a sealing means 7 between the impeller 2 and the pump housing 1, a pressure chamber 23 that is delimited by the pump housing 1, the impeller 2 and the sealing means 7. The pump housing 1 and the impeller 2 have a gap 24 between them via which the pressure chamber 23 is in communication with the discharge side 4 of the impeller 2. Pressurising means is connected to the pressure chamber 23 for forcing a liquid medium 21 into the pressure chamber 21 under excess pressure. The sealing means 7 comprise at least two lip seals 8, 9 positioned one after the other in the direction of the axis of the impeller 2, between which the lip seals 8, 9 the connection 20 for the pressurising means is located, the pressurised liquid 21 urging the lip seals 8, 9 into sealing contact with the sealing surface 17 of the shell 18.

Description

241 3604 I construction for a cenhiI=Tng The.venton relates to a seal

consS'iuction for sealing the impeller of a centrifugal pump on t]Ic Suction side with respect In flee bump housing, comprising at least one sealing means between the inpeller and the pump lousing, a pressure chamber that is delimited by the pump housing. the Per anal the sealing means, wherein the pump housing and flee impeller have a gap between them via which the pressure chamber is in communication with Else lisclarge side of Else speller, as Darrell as pressunsing means connected to tile pressure chamber for forcing a liquid into flee pressure chamber under excess pressure.

Such a seal conscior is known. The Pose of the sealing streams thereof is to prevent to punned medium flouting hacl Irom the discharge side of lye impeller to the suction side. Such a leakage Clove would severely adversely affect the efficiency, that is to say the ratio between the hydraulic power (pressure flow rate) and, tile motor power supplied (torque x revolutions) of flee cetifigal pump The purpose othe excess pressure lS in the pressure cluZlher is to obtain film contact pressure in the sealing Kneads The consequence of this excess pressure is that a fairly Large contact pressure and consequently also high diction with respect to the impeller is generated. However, Wi01 regard to wow tle friction should not be too high. For this reason a certain, [united leakage flow of Me pressure medium past the sealing means to the suction side is generated.

This known seal conductor has venous disadvantages. The pressure medium has an abrasive character, as A result of which wearing of the sealing Unmans nevertheless still occurs. However, it is not easily possible co remove abrasive particles Tom We pressure medium. This is caused by the fact that a fairly high How rate is necessary in order to generate Else desired pressure. Specifically, the pressure media flows out of We pressure chamber via the gap between impeller arid pump horsing. Said loss can be compensated for only by clmosing a high Pow rate.

However, the consequence of this high flow rate is that the liquid, usually seawater that has a sulstantial loading of particles as a consequence of dredging activity, does not leave suicide time to settle. Large basins would be needed to clean such water to an adequate extent in the desired quantities per Wit time. Tlus is not achieval;,le on board a vessel.

T he Bin of the irention is to provide a seal construction of the abovementioned type that does not have these disadvantages and the seal of which does not exhibit any substantial wear on Alec suction side. Said aiTn is achieved in that Me sealing means comprise at least two lip seals positioned one after the other in flee direction of the axis of the impeller, bctwc whelk lip seals ':hc conrectiou for flee pressuxising means is located.

Fitly the seal constnctiut, accorling to tlZC invention the pressure tnedium is fed into a pressure chamber that ii delimited bit the two lip seals, the impeller and tl:e pump IZOUSing Lucia a pressure clamber Is closed off fairly well and in any event better than the traditional, uressure chernher that As into a gap. The consequence of this good seal is that the desired pressure can lie generated by the pressure rnediun at an appreciably lower flow rate. Consequently, an appreciably smaller molt of pressure n-Zedi=ZZ is needed per unit tllllc, (Ire consequence of which is that the pressure medimn can be cleaned better, including on lizard a ship. As a result the leakage flows Cat are necessary With regard to reducing wear in the hp seals do not have act abrasive character, vluch has a beneficial effect on the life ol the lip seals.

Preferably,, the lip seals each have a Dexthle member with a fixing part, by means of which We lip seal is fixed to the housing, and with a sealing ring, as well as a sealing surface joined to the in:peller, against which sealing solace the internal sealing surface of tle sealing ring is kept pretensioned, whirls sealing ring is located win respect to the fixing part' on the side of said fixing pact facing the discharge side of the impeller. Tle sealing surface of tle lip seal that is located a relatively large distance away Join the discharge side of the impeller preferably has a pattern for transporting liquid Done the pressure chamber under the influence of the rotation of the impeller. this way, When the impeller rotates a leakage [low past the sealing ring which reduces fi iction is promoted.

The sealing surface of the lip seal Mat is located a relatively short distance al Coma tle discharge side of the impeller can also have a pattern for transporting liquid to the discharge side of the impeller.

According to a variant, further pressurising means can be connected to flee part of the pressure chamber that is located between the gap and the lip seal that is located a relativelSr short distance away tiom the discharge side of the impe11er. These conventional pressurising means function with a high flow rate, in view of tle relatively submental leakage that takes place via the gap between tile pump 1musing and Me impeller. Despite the Act that tile medium used with these pressuris means is necesmly reladvely severely contaminated, Were is still no wear as eonequence of the abrasive action of this pressure Tnedium. This is achieved in that the leakage Dow of the relatively clean pressure l medium prevents the contaminated pcssure medium being able to penetrate into the lip seal. The contaminated pressure medium is continuously flushed away lay tle clean [pressure rrefliunI whCIl the llupciler rotates.

I he invention firthcrmore relates to a centrifugal pump, comprising a pump housing, an impeller noted in the pump housing such that it can rotate, which impeller extends between a suction side and a lisclarge side, as well as a seal construction as described above between the pump housing and 1:hc impeller on the suction side thereof.

the invention will be explained in more detail below with reference to the figures.

Figure I shows a conventional centrifugal pump.

[figure 2 shows the seal construction according to the invention.

The conventional centngal pump shown in Figure I has a pUlD.p housing, indicated in its entirety by I, as well as an impeller 2. The pump housing 1 has an inlet 3 as well as a pressure chamber 4 fiom which the medium pressurised bar the impeller 2 can be discharged.

IS The impeller 2 is fixed at the end of flee shaft which is indicated in its entirety by 5 Ed is supported relative to the primp housing 1 in a known manner, which is not shown in more detail, such that it can turn. The shaft 5 is sealed win respect to the housing 1 by means of the shaft seal 6, Vehicle is known per se and tlerefiore is not described in snore detail.

On the suction side the impeller 2 is sealed with respect to die pump housing 1 by Ate seal construction indicated in its entirety by 7. This seal construction is inside We suction cover 27.

With reference to Figure 2, the seal construction 7 according to the invention has two lip seals indicated in their entirety by and 9, respectively. These lip seals 8, each have flexible nenber 10, i 1, evilly a fixing part 12, 13' by means of which they are faced to the pump lousing 1. The lip seals 8, 9 furthermore have a sealing Ens 14, 15. Finally, the lip seals 8, 9 also have a sealing surface 16, 17 trait is joined to the impeller 2. In Me illustrative embodiment Ybown. tle sealing surfaces 16, 17 are on the outside of the shell 18 that is fixed to the impeller ? With respect to the inlet 3' the shell 18 forms a narrow gap 19.

Between the lip seals 8, 9 Mere is a connection 20 fur supplying a pressure medic ?.1. This pressure medium pushes the seals ring 15 of the lip seal firmly onto the associated sealing surface 17 of the shell 18. To reduce the friction between the sealing nng / and the sealing surface 17, said sealing surface is provided with a pattern, for example a helical line ?2, tea transports the pressure medium 21 underneath Me sealing ring IS to the Inlet 3. In Ellis way the pressure ilium can reduce the diction between sealing ring 15 arid sealing surface Since tle pressure medium I has to be fed only at a low flow rate because of the fact that the pressure chamber 73 is dell sealed, this pressure media 21 can be cleaned mall.

Consequently, it has Tartly any abrasive action.

The pressure medians ? I CalL firthemore he transported between the sealing ring 14 acid the sealing surface 16 of the up seal 8, for example through a courtlier helical groove 24.

Here as well it is the case that there is a reduction in friction and hardly any freer. The pressure medium 21 is tI'en able to flow further to the discharge side 4 of Me centrifugal pump. This takes place a the gap '4 between the impeller 2 and We pump housing 1' According to a variant, the primp housing I can have second pressurizing means 2S, via svlich a second type old pressure neditun 26 cart be fed' This second pressure medians IS 26 has to be fed at a higher flow rate because this is in direct; communication with the gap 24 between the impeller 2 arid the pump housing it The second pressure medium 26 is consequently inevitably snore highly contaminated: usually tl:ere is not sufficient capacity on board a vessel to be able to treat surly high flow rates that acre needed for Me second type of pressure modicum 26.

Nevertheless, despite the use of this relatively contaminated second type of pressure medium 26, no wear lakes place as a result at the location of the lip seal 8' As ahead nentioued, the relatively clean pressure medium 21 is directed through Die gap oeeen Me sealing ring 14 Ad the sealing surface 16 of Me lip seal 8. The second type of pressure medium 26 is thus continuously flushed away with respect to lhe lip seal 8.

Claims

(plains 1. Seal construction for sealing the impeller (a) of a centnigal

primp on the suction side (3) with respect to tle pump housing (1), comprising a sealing means (7) between Me impeller (a) and the pump housing (1), a pressure chamber (21) that is delimited lay the pump housing (1), the impeller (2) and tle sealing sneaks (7), wherein the pump housing (I) and the impeller (2) have a gap (ad) between them via which the pressure cleanser (21) iS in communication with the discharge side (4) of We impeller (2), as well as pressurizing means connected to the pressure clamber (71) for forcing a liquid (23) into the pressure chamber (21) under excess pressure, characterized in that the sealing means (7) comprise at least two lip seals (8, 9) positioned one after the other in the direction of the axis of Me unlikelier (2t, between which lilt seals (S. 9) the connection (20) for the pressurizing means is located.
2. Seal construction according to Claim 1, wherein Me lip seers (8, 9) each have a flexible member (10, 11) with a fixing part (12, 13), by means of which the lip seal (8, 9) is fixed to the pump housing (1), arid with a sealing ring (14, 15), as well as a sealing surface (16, 17) joined to the impeller (a), against which sealing surface the internal sealing space of the sealing ring (14, 15) is kept pretensioned, which ealirg ring (14, 15) is located, with respect co the fixing, part (12, 13), on the side of said fixing part (12, 13) facing the discharge side (4) of the impeller (2).
3. Seal construction according to Clalrn 2, wherein the sealing surface (17) of Me lip seal (9) that is located a relatively large distance away Morn the discharge side (4) of We impeller (2) has a pattern (22) for nonsporting liquid loom the pressure chamber (21) under the influence of the rotation of the impeller (23.
4. Seal construction according to Claim or 3, wherein Me sealing suede (163 of the lip seal (8) that is located a relatively short distance away Come the discharge side (4) of the impeller (2) has a palm (17) for Ransoming liquid to the discharge side (4) of We impeller (2).
5. Seal construction according to one of the precede claims, Yyberan rlher pressunsino unmans (05 arc connected to tile part of the pressure chamber Mat is located between the gap (?.) and Alec lip seal (hi) cleat is locat.ecl a relatively short distance away from the discharge side (4) fit the Ells (2) f, Centul,al pump, eomprisrP, a primp housing (I), an impeller (2) mounted in the pump hocusing (1) such that it can ratate, Rich impeller extends between a suction side (3) and a dischar;,e side (a) , as well 5 a seal construction according to one of the preceding claims beta een the primp LZOUSU\g ( I) anal flee impeller (A on the suction side (3) thereof.