GB2237603A

GB2237603A - Liquid-ring vacuum pump

Info

Publication number: GB2237603A
Application number: GB9020646A
Authority: GB
Inventors: Martin Staehle
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-17
Filing date: 1990-09-21
Publication date: 1991-05-08
Also published as: HU204117B; DK212890A; GB9020646D0; IT9012513A1; IT1242222B; HU905778D0; JPH03145593A; DE4032036A1; DK212890D0; IT9012513A0; HUT55094A

Abstract

On the outer surface of the rotor (1a) an annular channel is provided, which is interrupted by a transverse barrier (17). At the front of the barrier (17), in the rotational direction, a passage (18) connects to the pressure chamber (14), whilst at the roar of the barrier, a passage (19) connects to the suction chamber (13) so that air is alternately sucked (via passage 13) into the sickle shaped hollow space (9) which exists and forced out therefrom (via passage 14) as the rotor rotates. The pump is particularly suitable for liquids which are contaminated with particulate matter, as there are no narrow gaps. <IMAGE>

Description

SJL140990 LIQUID-RING VACUUM PUMP 1.

:2 -7 C=, 0 ---:3 Liquid-ring vacuum pumps are known which have a rotor eccentrically mounted within a housing of circular interior and provided with elements which rotate the liquid within the housing to form a rotating ring, which, due to the eccentric disposition of the rotor in relation to the interior of the housing, contacts the rotor in one region, thereby forming a localised seal, whilst at the other side a cross-sectionally sickle-shaped cavity is created between the rotor surface and inside diameter of the rotating liquid. Elements mounted onto the rotor divide the said cavity into cells into which gas is taken from the suction-side of the pump and transferred to the pressure side. These known pumps can be divided into two types:

Systems such as those disclosed in-patent specifications D.R.P 28893 and D.R.P 56529, in which only relatively narrow sealing gaps are formed between the suction- and the pressure-side of the housing, i.e. between the rotor and its blades on the one hand and the housing wall on the other hand, which systems can only make use of liquids (i.e. uncontaminated with particulate matter).

2. Systems, such as those disclosed in patent specifications GB 1425997, D 883,565, U.S. 2,280,100, which have worm-drive blades arranged on the rotor and do not depend on laterally tight sealing gaps, but instead move the cavities necessary for conveying gas in the axial direction between the wormdrive walls. Such systems, of course, can suitably make use of impure liquids, i.e. liquids which are contaminated with particulate matter, as they tend not to suffer from the risk of clogging.

1 SJL140990 2.

The main disadvantage of the wormdrive system over system (1) is that turbulence develops in the liquid ring due to the axial movement caused by the worm-drive movement, thus causing loss of energy and unstable conditions at the inner region of the liquid-ring. EPA-111653 discloses measures which can be taken to counter this axial flow, but even then it could only be reduced, not prevented.

An object of the present invention is to provide a system which does not mechanically produce an axial flow in the water ring, yet still permits the use of contaminated liquids, as there are no narrow gaps.

According to the present invention a cylindrical rotor, eccentrically mounted in a pump housing is provided with a continuous (annular) channel around its outer circumferential surface and a barrier is mounted in this channel and respective passageways are provided between the channel and the pressure chamber at the front side of the barrier, considered in the directioh of rotation, and between the channel and the suction chamber at the rear side of the barrier, considered in the direction of rotation.

The suction- and pressure-sides of the housing space are linked with respective inlet and outlet openings of the pump.

Within the rotor channel, elements, for example small vanes, providing transverse surfaces may be mounted at spaced intervals on the channel side walls to promote or enhance the liquid motion. These elements should be of sufficient size to ensure that power transfer to the co-rotating liquid ring is adequate to maintain the sickle-shaped cavity inside the liquid ring, whilst leaving sufficient channel crosssectional area to allow for the flow of gas within the 1 SJL140990 3 channel.

The barrier moves through the sickle-shaped cavity, forcing the gas contained in the cavity portion ahead of itself towards the transverse opening in the channel side wall and thence into the pressure chamber, from where it reaches the pump outlet via an opening near the centre of rotation. At the same time, gas is sucked through the transverse opening rearward of the barrier from the suction chamber into the cavity.

The pump operation is cyclic in that the barrier within the cavity crosses the sickle shaped cavity and then the liquid seal sector, where the liquid ring is in contact with the base of the channel, once per rotation, resulting in conveying of gas in a pulsed manner.

More balanced transmission of gas can be achieved if the pump is arranged to be multi-flow with a greater number of substantially parallel adjacent channels on the circumferential surface of the rotor and more than one barrier and associated openings providing passages between respective channels, resulting in ducting of the gas in labyrinth-like manner from one channel to the other, from the suction chamber to the p2essure chamber.

An increased vacuum is also obtained when the pump is in multi-stage format with several parallel rotor channels, designed to form a labyrinth.

Finally, the two above principles can also be combined into a multi-flow, multi-stage liquid-ring vacuum pump.

The invention will be explained further by way of example, 1 SJL140990 with reference to the accompanying drawings, in which:

Fig. 1 is an axial cross-section of the first embodiment, namely a singleflow, single-stage pump; Fig. 2 is a plan view of the rotor and the liquid ring of the Fig. 1 embodiment, as seen from the suction side; Fig. 3 is an axial cross-section, comparable to Fig. 1, but of a second embodiment, namely a dual flow and multi-stage pump; and Fig. 4 to 8 are cross-sectional views of the rotor and liquid ring, at successive channel stages as seen from the suction sLde, and all shown at the same rotor turning position of the cycle.

With reference to Fig. 1, in the first embodiment, the rotor la is mounted on shaft 2, which is'eccentrically mounted in the housing 4, being supported at one end of the housing in bearing 3. Housing 4 has a suction-sided inlet 5 and a pressure-sided radial outlet 6. In use the liquid ring 7 rotates, in the interior space of the housing, forming a sickle-shaped cavity 9 relative to the base 8 of a circumferential channel in the rotor la, and a sealed zone 10 on the opposite side.. The lateral walls 11 of the channel define the axial extent of the cavity 9. The outer periphery of the rotor la around its entire circumference is immersed in th.e liquid ring, thus sealing the rotor channel and simultaneously divicling the housing interior space into a suction chamber 13,-which is connected to the inlet opening, and a pressure chamber 14, which is connected to a pressureoutlet chamber 15, which in turn is connected to the outlet 1 SJL140990 5.

6. The shaft mounting is sealed off from the aforesaid pump chambers by a seal 16. A barrier 17, is transversely mounted within the rotor channel thereby interrupting the continuity thereof. At the front side of this barrier (in the direction of rotation) an opening 18 is provided in the wall of the channel, thereby connecting this channel to the pressure chamber 14, while at the rear side of this barrier 17 a further opening 19 connects to the suction chamber 13. Liquid-ring impeller vanes 20 are attached to the channel wall.

Turning now to Figs. 3 and 4, the second example shown is a dual flow/multi-stage pump. In this case the rotor lb has four circumferential channels I to IV, arranged side by side, which are connected in sequence to one another and to suction chamber 13 and pressure chamber 14. Barriers 17a to 17h, opening passageways al to el, a2 to e2 and the respective lateral channel walls 11 form a labyrinthine system. It will be noted that there are in this case two diametrically opposed barriers in each channel, each with an associated forward and rearward passageway. Thus, a first flow path is, by way of the sickle-shaped cavities, in the sequence indicated at 9 1 1 to 9 IV 1, whilst a second flow path is by way of the cavities in the sequence 9 1 2 to 9IV 2 (Figs 4 to 8).

The diameters of the respective channels I to IV are appropriately matched to the axially varying inside diameter if the liquid ring due to pressure increase through the hollowing interior space.

The illustrated pumps operate as follows: The single-stage pump in Fig. 1 is the simplest arrangement of the invention. The sickle-shaped cavity 9, defined SJL140990 6.

between the channel base 8, the lateral walls 11 of the channel and the liquid ring 7, is periodically connected, by passages 19, to gases in the suction chamber 13. The barrier 17, moving through the cavity 9, results in an increase in the volume of the part of the cavity connected to the suction chamber 13, thus sucking in gas from inlet 5 through suction chamber 13 and passage 19. At the front of the barrier 17 the gas caught in the cavity by the previous cycle is compressed and conveyed through passage 18 via pressure chamber 14, outlet chamber 15 to outlet 6 of the pump. The vanes 20 mounted in the channel assist the rotary movement of the liquid-ring. All elements convey only radial components to the liquid ring, thus incurring less loss of energy and a minimum of operating liquid consumption due to more stable liquid ring inner contours. (The liquid used is customarily water).

The dual-flow and multi-stage pump illustrated in Fig. 3 operates on the same principles as the Fig. 1 embodiment. In this case, the rotor lb has four parallel channels I to IV and during rotation there are two pulsating gas streams 1 and 2 moving from suction chamber 13 to pressure chamber 14 through al - 9 1 1 - bl 9 11 1 - cl - 9 111 1 dl - 9 IV 1 - el, or respectively a2 9 1 2 - b2 - 9 11 2 c2 - 9 111 2 - d2 - 9 VI 2 - c2. These are superimposed on one another at 1800 phase displacement, thereby smoothing the pulsation.

S3L140990 1

Claims

7 A liquid-ring pump comprising a cylindrical rotor, eccentrically mounted for rotation inside a cylindrical housing space, the outer circumferential periphery of the rotor communicating, in use, with a co- rotating liquid ring, thereby dividing the housing space into a suction chamber and a pressure chamber, characterised in that an annual channel provided around the outer surface of the rotor is interrupted by a transverse barrier, and respective passageways are provided between the channel and the pressure chamber at the front side of the barrier, considered in the direction of rotation, and between the channel and the suction chamber at the rear side of the barrier, considered in the direction of rotation.
2. A liquid-ring pump as claimed in claim 1, wherein vanes which impart motion to the liquid ring are mounted at spaced intervals in the annular channel.
3. A liquid-ring pump as claimed in claim 1 or 2, and provided with several annular channels adjacent to one another on the outer surface of the rotor, these channels being connected to one another by passages through their separating walls, so that the pump is multi-flow and/or multi-stage.
4. A liquid-ring pump substantially as hereinbefore described with reference to and as illustrated by Figs 1 and 2 or Figs. 3 to 8 of the accompanying drawings.

Published 1991 at The Patent Office. State House, 66/71 High Holborn, London WC I R47?. Further copies maybe obtained from Sales Branch. Unit 6. Nine Mile Point Cwrmclinfach. Cross Keys, Newport. NPI 714Z. Printed by Multiplex techniques lid, St Mary Cray. Kent.