GB2261709A - Pumps - Google Patents

Abstract

A pump, especially for removing liquid from boreholes, comprises a housing (30) provided internally with a diaphragm (36) to define two chambers (38, 40). The pressure in one chamber (38) can be varied, for example by being connected to a compressor via a rotary valve. The diaphragm (36) is displaceable in response to pressure changes in said one chamber to effect movement of fluid through the device, e.g. in a pulsed flow. The pump can be used with noxious fluids as there are no working parts in contact with the fluid being pumped. In an alternative embodiment, a flat diaphragm (1, Fig. 1) is displaceable alternately into two chambers (9, 11, Fig. 1), so that the internal volume of the chamber into which the diaphragm moves becomes substantially zero. <IMAGE>

Description

PUMPS This invention relates to means for the transport of fluids, in particular pumps and the like.

Known devices for transporting fluids rely on mechanical means to propel the fluid, the mechanical means being coupled directly to a drive means. Such pumps are generally complex, having many moving parts subject to wear and can be corroded by contact with noxious fluids. The erosion of mechanical parts reduces the pumping efficiency and necessitates frequent and expensive replacement of parts.

It is an object of the invention to provide a device for the transport of fluids that is of simple construction and which has no working parts in contact with the fluid.

In accordance with the present invention there is provided a pumping device comprising a vessel which is provided internally with diaphragm means to define at least two chambers, one of said chambers being connectable to means to vary the pressure within said one chamber, and the vessel having inlet and outlet conduits for pumped fluid to enter and leave the vessel, the diaphragm means being displaceable in response to said pressure-varying means to induce pressure changes in the other chamber or chambers to effect movement of fluid through said conduits.

In one embodiment, the vessel has two internal chambers, and the diaphragm means is displaced alternately into the two respective chambers so that the internal volume of the chamber into which the diaphragm means moves becomes substantially zero.

Each conduit may contain a non-return valve positioned in the appropriate sense in each conduit so that fluid flows into the vessel through one conduit, and out of the vessel through the other conduit.

In another embodiment the two chambers are arranged one within the other along the length of an elongate housing, with the diaphragm means expanding and contracting substantially radially in response to pressure changes.

Conveniently the vessel has an orifice sealably connected to a conduit which connects to a compressor. This conduit may contain a rotary valve in order to reversibly change the pressure in the vessel.

The frequency of the pressure changes can be designed to relate to the displacement of the compressor and the amount of fluid transported by a single flexing of the diaphragm means.

The basic device according to the invention provides a pulsed flow of fluid. However, a plurality of such devices working cooperatively, e.g. a twinheaded or multi-headed unit, can be used to give a continuous flow.

The invention has advantages over conventional means of pumping as there are no working parts in contact with the fluid to be pumped. If the vessel and the diaphragm means are constructed from suitable materials, the device can transport noxious fluids such as acids.

A further advantage of the invention is that its simple construction allows ease of maintenance, repair and cleaning. It can be used either in close proximity to or remote from the means used to alter the pressure in the vessel, and can be lowered down a wellhead for the pumping of both clean and toxic fluids.

Two specific embodiments of pump in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a sectional view through a first embodiment of pump, when not in use; Fig. 2 is a view as shown in Fig. 1 when fluid is being admitted into the vessel; Fig. 3 is a view as shown in Fig. 1, when fluid is being expelled from the vessel; and Fig. 4 is a longitudinal view, partly in section, through a second embodiment of pump in accordance with the invention.

The pump shown in Figs. 1 to 3 comprises a flexible diaphragm 1 sealably sandwiched between flanges 3, 5 of two halves of a vessel 7, thus forming upper and lower chambers 9, 11. The upper chamber 9 is sealably connected through a pipe 13 containing a rotary valve (not shown) to a compressor (also not shown). The compressor may be driven by any suitable means, for example an electric motor, petrol engine or hydraulic motor. The lower chamber 11 has inlet and outlet pipes 15, 17 containing non-return valves 19, 21. Inlet pipe 15 leads to the source of fluid to be pumped and outlet pipe 17 is connected to an appropriate discharge outlet.

In operation, as shown in Fig. 2, the air pressure in the upper chamber 9 is reduced by the compressor, which causes a pressure difference across the flexible diaphragm 1 whereby the diaphragm 1 moves upwards into the upper chamber 9 and fluid flows into the lower chamber 11 through the inlet pipe 15 in order to equalise the pressure in the two chambers. The non-return valve 21 prevents back flow of fluid from the outlet pipe 17 into the lower chamber.

The rotary valve then admits air through the compressor pipe into the upper chamber 9, as shown in Fig. 3. This forces the flexible diaphragm 1 down into the lower chamber 11 due to the greater pressure in the upper chamber and expels fluid through outlet pipe 17.

The non-return valve 19 in the inlet pipe prevents fluid from being forced back through the inlet. The rotary valve connects the compressor to the upper chamber and the pumping cycle repeats.

Pressures as low as 762 mm/Hg can be attained in the upper chamber, with a pressure difference between the upper and lower chambers of less than 25 mm Hg.

The device can be used as part of a system for removing water, such as those that use lances to lower the water table for example on construction sites; or for raising groundwater for irrigation purposes. If appropriate heads are fitted to the working end of the inlet pipe, adjacent to the water to be pumped, the device can lift surface water from playing surfaces of leisure complexes, such as golf courses, or can dry out flooded floors of cellars. It has been found that devices constructed according to this embodiment of the invention can remove water at a rate of several thousand litres per hour.

A particular application of the pumping device is in the removal of liquid from land-fill sites where rubbish and waste has been dumped. For deep sites a hole is made down through the mass and the whole pumping device can be lowered down the hole, on the pipe from the compressor, thus overcoming the problem that liquid can normally be raised only through relatively short distances.

The pump described above is particularly effective for insertion into boreholes which have relatively large diameters. However, for applications where it is necessary to lower a pumping device down a narrow borehole, a pump such as will now be described with reference to Fig. 4 may be more appropriate. This pumping device can be used in boreholes of just a few inches in diameter. It is preferably embodied as a pneumatic pumping head which functions with a pneumatic pulsing action.

As shown in Fig. 4, the pumping head comprises a cylindrical tube 30, which is preferably of metal, and which is closed by end caps 32 and 33.

Each end cap 32, 33 has associated therewith a tubular pipe or conduit which incorporates a non-return valve 34. In the illustrated embodiment the non-return valve 34 at the bottom of the pumping head serves as an inlet valve and the non-return valve 34 at the upper end of the pumping head serves as an outlet valve.

Within the interior of the tube 30 is a flexible member 36, for example of rubber or plastics material, which is annular and which is anchored at each end between the end of the tube 30 and the respective end caps 32 and 33. This therefore defines an annular outer chamber 38 within the tube 30 and an inner chamber 40 within the flexible member 36. The cylindrical tube 30 has a hole therethrough which is connected to a tube or pipe 42 which is connected to means (not shown) to vary the pressure within the tube 42 and thus within the outer chamber 38.

In use, a reduction of the pressure in tube 42 will induce a reduction of the pressure in the outer chamber 38 and will cause the flexible member 36 to "inflate" because of the greater pressure within the flexible member. This will cause a reduction in the pressure within the flexible member 36, thereby drawing liquid in through the lower non-return valve 34. When the pressure in tube 42 and thus in chamber 38 is increased, the flexible member 36 will contract again to the position shown, causing the liquid within the inner chamber 40 to be ejected upwards through the upper non-return valve 44. Thus, the application of pulses of pressure to the tube 42 and thus to the outer chamber 38 will cause liquid to be drawn up through the pumping device in the form of a pulsed flow.

Claims (8)

CLAIMS:

1. A pumping device comprising a vessel which is provided internally with diaphragm means to define at least two chambers, one of said chambers being connectable to means to vary the pressure within said one chamber, and the vessel having inlet and outlet conduits for pumped fluid to enter and leave the vessel, the diaphragm means being displaceable in response to said pressure-varying means to induce pressure changes in the other chamber or chambers to effect movement of fluid through said conduits.

2. A pumping device according to claim 1, in which the vessel has two internal chambers and the diaphragm means is displaced alternately into the two respective chambers so that the internal volume of the chamber into which the diaphragm means moves becomes substantially zero.

3. A pumping device according to claim 1, in which the vessel is an elongate housing and the diaphragm means extends longitudinally within the housing, with displacement of the diaphragm means being substantially radially of the housing.

4. A pumping device according to claim 2, in which the diaphragm means is generally tubular and extends the length of the housing, thereby to define an annular chamber between the diaphragm means and the housing which is connected to the pressure-varying means.

5. A pumping device according to any preceding claim, in which each conduit contains a nonreturn valve.

6. A pumping device according to any preceding claim, in which the vessel has an orifice sealably connected to a conduit which is arranged to be connected to a compressor.

7. A pumping device according to claim 6, in which the conduit to the compressor includes a rotary valve.

8. a pumping device substantially as hereinbefore described with reference to Figs. 1 to 3 or Fig. 4 of the accompanying drawings.