GB2303879A

GB2303879A - Liquid ring pump

Info

Publication number: GB2303879A
Application number: GB9515721A
Authority: GB
Inventors: Keith Mangnall
Original assignee: Hick Hargreaves and Co Ltd
Current assignee: Hick Hargreaves and Co Ltd
Priority date: 1995-08-01
Filing date: 1995-08-01
Publication date: 1997-03-05
Anticipated expiration: 2015-08-01
Also published as: GB9515721D0; GB2303879B

Abstract

A liquid ring pump comprises an impeller mounted eccentrically in a cylindrical chamber having a suction inlet 2 communicating with inlet duct 5, a discharge aperture 3 communicating with outlet duct 6 and being closed by end closure members, and a compression ratio regulator member 7, fig 2, located in the discharge aperture 3 and having at least one outlet port 8 communicating with the chamber. As shown, the member 7 has a plurality of ports 8, the total area of which relative to the suction inlet area determines the compression ratio of the pump. A diaphragm (10, fig 3) may be provided to close the ports 8 when the pressure within the chamber is below a certain level.

Description

LIQUID RING PUMP The present invention relates to a liquid ring pump.

A liquid ring pump comprises a cylindrical chamber housing an eccentrically mounted impeller. In use of the pump, the impeller is rotated and a working liquid present in the chamber forms an operational envelope around the walls of the chamber. Gas is drawn through a suction inlet into the chamber and is held in a pocket defmed between two adjacent impeller blades and the operational fluid. The gas is held in this pocket until the impeller rotates sufficiently for the pocket to communicate with a discharge outlet of the chamber through which the gas exits at a higher pressure than that at which it entered the chamber.

It is known that the compression ratio of a liquid ring pump is a function of the ratio of the area of the suction inlet to the discharge outlet. Generally the suction inlet and the discharge outlet are provided in a cast end plate assembly for the chamber. For a given size of end plate and suction inlet, pumps of different compression ratios may be produced using end plates having different areas of discharge outlets. Typically this is achieved by providing, in the end plate, different numbers and/or sizes of discharge outlet ports (or perforations) through which gas may exit from the chamber. However the production of a range of end plates each having the required number and/or size of discharge outlet parts to cover all compression ratios obviously presents manufacturing difficulties, particularly if the end plate forms part of the casing of the pump.It is therefore generally the case that only a limited range of end plates are produced. To provide for a specific compression ratio, ball valves may be associated with the perforations. The valves are such as to open in the event of over-compression and to close in the event of under-compression. Such ball valves can however be difficult to install, particularly if the end plate forms part of the casing of the pump.

It is therefore an object of the present invention to obviate or mitigate the above mentioned disadvantages.

According to the present invention there is provided a liquid ring pump comprising an impeller eccentrically mounted in a cylindrical chamber having suction inlet and discharge outlet arrangement and being closed by end closure members wherein the discharge outlet arrangement comprises a discharge aperture formed in the end closure member and a compression ratio regulator member located in said aperture and having at least one outlet port communicating with the chamber.

The compression regulator member preferably seats in the in the discharge aperture of the end closure member.

In the pump of the invention, the number and size of the ports in the compression regulator member assembly (and the extent to which it fixes the discharge area) determines the compression ratio of the pump. Thus in order to produce a range of pumps each having the same size of end closure member but having a different compression ratio, it is possible simply to produce a "standard size" end closure member (having a certain size of discharge aperture) and to provide a range of compression regulator members each for achieving a desired compression ratio. Thus problems of producing a range of different end closure members is avoided in favour of the much simpler task of producing a range of compression regulator members which may, for example, be in the form of a plate having the required number of outlet ports.Compression regulator members may easily be produced for any required compression ratio.

The invention has a particular advantage where the end closure member is a casting forming part of the casing of the pump.

Preferably the outlet side of the compression regulator member is covered by a flexible diaphragm (eg of the type disclosed in UK-A- 1118110) designed to open the ports in the compression regulator member for discharge of gas only when the pressure in the chamber exceeds a predetermined value.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a view of an end casing for incorporation in a liquid ring pump in accordance with the invention; Fig. 2 is a view (from the same side as Fig. 1) of a compression regulator member for incorporation in the casing of Fig. 1; Fig. 3 shows the reverse side of the member shown in Fig. 2; and Fig. 4 is a view looking in the direction of arrow A of Fig. 3.

Referring firstly to Fig. 1, there is illustrated a cast end casing 1 for a liquid ring pump. The illustrated end casing is a one-piece component incorporating a suction inlet 2 and a discharge aperture 3 having a peripheral ledge 4. The casing further includes an inlet duct 5 communicating with such an inlet 2 and an outlet duct 6 communicating with discharge aperture 3.

Reference is now made to Fig. 2 which illustrates a compression regulator member 7 for incorporation in the discharge aperture 3. The compression regulator member has a plurality of discharge ports 8 and (on its reverse side - see Fig. 4) is provided with a shoulder 9 whereby the member 7 may be seated on the ledge 4.

The number and size of the discharge ports 8 is such that the ratio of the area of the suction inlet to the total area of the discharge ports 8 provides the desired compression ratio for the liquid ring pump.

Provided on the reverse side of the compression regulator member 7 is a diaphragm 10 (to act as a non-return valve member for the discharge port 9). The diaphragm 10 serves to close the ports 8 when the pressure within the chamber of the liquid ring pump is below a predetermined level.

It will be appreciated from the foregoing description that a single type of end casting may be used for constructing a liquid ring pump having any desired compression ratio since it is an easy task to produce a compression regulator member having the required number and size of discharge ports 8 for providing that compression ratio.

Although the invention has been described with specific reference to a single stage liquid ring pump, it will be appreciated that the invention may be applied to a multistage pump more particularly, a compression regulation member may be provided at the discharge aperture of each section of the pump, thus considerably simplifying the construction of such apump.

Claims

1. A liquid ring pump comprising an impeller eccentrically mounted in a cylindrical chamber having suction inlet and discharge outlet arrangement and being closed by end closure members wherein the discharge outlet arrangement comprises a discharge aperture formed in the end closure member and a compression ratio regulator member located in said aperture and having at least one outlet port communicating with the chamber.

2. A pump as claimed in claim 1 wherein the end closure member is a casting forming part of the casing of the pump.

3. A liquid ring pump substantially as herein before described with reference to Figs. 1 to 4 of the accompanying drawings.