WO2019097420A1

WO2019097420A1 - An apparatus and method for underground water extraction

Info

Publication number: WO2019097420A1
Application number: PCT/IB2018/058954
Authority: WO
Inventors: Gerrit Stephanus PRETORIUS
Original assignee: Pretorius Gerrit Stephanus
Priority date: 2017-11-17
Filing date: 2018-11-14
Publication date: 2019-05-23

Abstract

This invention relates to an apparatus (10) and a method for underground water extraction. The apparatus (10) includes a single continuously open-ended casing (12) having an infiltration element (14) for sand water connected at an operatively lower end thereof to operatively permit water to enter the casing (12). A pump and motor assembly (18) for operatively displacing water from the infiltration element (14) to a delivery pipe (16) is provided and a lid on the upper end of the casing (12) is provided. A sealed connection between the delivery pipe (16) and the lid operatively provides an outlet of the apparatus (10) to allow extracted water to be displaced to any desired location above the surface. The pump and motor assembly (18), in use, provides negative pressure to facilitate accelerated filtration of water through the infiltration element (14) into the delivery pipe (16).

Description

AN APPARATUS AND METHOD FOR UNDERGROUND WATER

EXTRACTION

FIELD OF THE INVENTION

This invention relates to an apparatus and method for underground water extraction, more particularly, to an apparatus and method for extracting water from underground layers of water-bearing materials, particularly riverbeds, aquifers and the like.

BACKGROUND OF THE INVENTION

Water is an essential component of life. With current climate changes around the world, together with a growing population, water resources are under increased threat. Accordingly, means of extracting water which is useful in agriculture, manufacturing of various products and human consumption is vital.

Water extraction is the process of taking water from a source and making it available for any useful purpose. Many sandwater extraction apparatuses and methods are known and particularly apply to extraction in sandy river beds. Many rivers are dry at the river bed for most of the year, but water continues to run in the river course below the sand surface. Sandwater extraction is typically used in these instances to draw water from below the surface. Water is also typically extracted from the landward side of seaside sand dunes or from deep in the sand beds of lagoons and estuaries and the like where at least a water which is considerably purer is present. These processes have become more important due to climate changes and the growing population as alluded to above.

Typical apparatus used in these sandwater extraction applications are simple perforated conduits which are installed underground and which include a pump to displace the water from below to above the surface. The perforated portion of these conduits is typically known as a screen or filter and is operatively located below the water table to allow water to filtrate into the conduit from where it is pumped to above the surface.

A disadvantage of these apparatuses include that it relies on gravitational force as well hydraulic pressure in order to filtrate water into the conduit. It follows that the flow of water into the conduit is fairly slow making the extraction process slow and cumbersome and, in some instances, uneconomical.

A further disadvantage is that these conduits typically include a filter pack around the conduit, typically of cement or sand. This not only makes the equipment fairly expensive and cumbersome to operate and maintain, but also delays the natural filtration into the apparatus.

A yet further disadvantage of known apparatuses includes that some of the components, such as the pump, are located above the ground surface exposing it to outside elements and necessitating the building of protective structures over the exposed components. This disadvantage is further exacerbated in installations in river beds where the components are exposed to flash flooding.

OBJECT OF THE INVENTION

Accordingly, it is an object of the present invention to provide an apparatus and method for underground water extraction with which the applicant believes the aforementioned disadvantages may at least be alleviated or which may provide a useful alternative for known apparatuses and methods for underground water extraction.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an apparatus for underground water extraction, comprising

a single continuously open-ended casing; - an infiltration element for sand water, connected to an operatively lower end of the casing which operatively permits water to enter the casing;

- a lid on the upper end of the casing to seal the casing;

- a pump and motor assembly for operatively displacing water from the infiltration element to a delivery pipe;

- a sealed connection on the lid to operatively seal at least the pump inlet of the pump and motor assembly inside the casing;

characterized in that the pump and motor assembly, in use, provides negative pressure to facilitate accelerated filtration of water through the infiltration element into the delivery pipe.

The invention further provides for the infiltration element to comprise of any one or more of the group consisting of a stack of filter rings, a screen, a slotted conduit.

The invention yet further provides for the casing to be sealed with the lid at its top by matching flanges of the casing and lid; by complimentary screw-threads on the casing and the lid; or by chemical adhesive between the casing and the lid, to create negative pressure inside the casing when operative; and wherein the lid has an opening to which the pump of the motor and pump assembly or the delivery pipe is connected and tightly sealed. The invention further provides for at least one air-release valve proximate the upper end of the casing or on the lid. The air-release valve may be a mechanical or an electronically operated valve.

The invention further provides for the motor of the motor and pump assembly to be a fixed speed motor or a variable speed motor.

The invention yet further provides for the pump and motor assembly to be configured to permit flushing of the infiltration element.

The invention yet further provides the flushing of the infiltration element to include flushing with water and/or chemicals. The invention yet further provides for a plurality of separate infiltration elements to be provided along the casing.

The apparatus may operatively be installed such that all components except an end of the delivery pipe is located below the ground surface.

In accordance with a second aspect of the invention there is provided for a method of extracting underground water including the steps of installing an apparatus as provided in the first aspect of the invention such that at least the pump inlet of the pump and motor assembly and infiltration element are located within an underground water-bearing body; and actuating the motor and pump to provide negative pressure such that filtration of water through the infiltration element into the delivery pipe is accelerated.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying figures wherein:

Figure 1 is a cross-sectional elevation of an apparatus for underground water extraction according to a first embodiment of the invention; Figure 2 is a cross-sectional elevation of an apparatus for underground water extraction according to a second embodiment of the invention;

Figures 3 & 4 are cross-sectional elevations of an apparatus for underground water extraction according to third and fourth embodiments of the invention; and Figure 5 shows a diagrammatical representation of an apparatus having a plurality of infiltration elements.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

As shown in the figures, an apparatus for underground water extraction is generally indicated by reference numeral 10. It will be understood that in the particular embodiments described below, sandwater is extracted, however the invention is suitable for purposes of extracting underground water including water contained in any water-bearing body such as aquifers and the like.

The apparatus 10 generally consists of a single continuously open-ended casing 12 with a sealed lid at it operative top end which houses an infiltration element 14, delivery pipe 16 and a pump and motor assembly

18 which, in use, forms a closed system capable of extracting water from a surrounding sand body 20 to an outlet 22 at a delivery point X above the surface of, for example a river bed, where it can be displaced to the desired or required location for further use.

The apparatus 10 may be installed in the usual manner for example by drilling or excavating of a suitable hole for installation. The apparatus 10 may also be installed by directing pressurized water to the sand in the desired location. This is similar to the reverse washing procedure, or “flushing” mentioned below in more detail. In this instance, the pressurized water will result in the sand becoming less dense to such an extent that the apparatus 10 can simply be dropped into place without the need of drilling or digging into the surface of the riverbed.

As shown in the embodiments, the infiltration element 14, is in direct contact with water in the surrounding sand body 20 and permits water to enter the casing 12. The pump and motor assembly 18 is provided to operatively displace water from the infiltration element 14 into the delivery pipe 16. It will however be understood that the pump and motor assembly 18 provides negative pressure to facilitate filtration of water through the infiltration element 14 into the delivery pipe 16 and to displace the water to the outlet 22 at the delivery point X above the surface. In addition, or alternatively any suitable pumps or means to displace the water from the delivery pipes to any desired location may be provided without departing from the scope of the invention. Similarly, the outlet 22 may have any suitable connection with the delivery pipe 16, such as a socket (not shown) to provide a means of delivering the extracted water to the delivery point X.

The casing 12 is water impermeable and encloses all the components including the pump and motor assembly 18 and the delivery pipe 16. The casing 12 has a flange 24 complimentary shaped to a flange 26 of the delivery pipe 16 where the delivery pipe 16 exits the casing 12 at the outlet 22. A collar 28 is provided to align the delivery pipe 16 and casing 12 and a seal 30 is provided between the flanges 24, 26 to sealingly close the components to prevent the ingress or escape of air or water and provide a closed system for operation as will be described in more detail below. The flanges 24, 26, collar 28 and seal 30 operatively forms a lid on the upper end of the casing to seal the casing 12 and the components housed therein. The lid may furthermore be a separate component to the casing 12 and delivery pipe 16. It will also be understood that any alternative mechanism or component, such as complimentary screw-threads on the casing and delivery pipe may also be provided to connect and seal the casing and delivery pipe without departing from the scope of the invention. In addition, a socket (not shown) may also be provided to connect the upper end of the delivery pipe 16 at the outlet 22 of the apparatus 10 which may be connected to any means to deliver the extracted water to the desired location.

At its operative bottom end, the delivery pipe 16 opens only to the pump of the pump and motor assembly 18 such that water is displaced along the delivery pipe 16 upwardly through the outlet 22 to the delivery point X where it can be further displaced in known manner to the necessary or desired location for further use. As mentioned above, the pump and motor assembly 18 is configured to provide negative pressure, in other words a suction power to the water such that filtration through the filter is facilitated and enhanced. As shown in figure 1 , the water level must be above level B to ensure that the pump and motor assembly 18 is submerged in water to maintain its operation as any air-intake into the pump will cause the pump to switch off. This provides a closed system which enables continued functionality of the apparatus 10 and which facilitates the extraction and supply of water through utilizing the negative pressure from the pump and motor assembly

18. This furthermore enables a net positive suction head to provide improved extraction of water.

The lengths and diameters of the various components can be varied according to the conditions, in particular in accordance with the level of water in the surrounding sand body 20 and the quantity of water to be pumped per unit time. In the embodiments described, the pump and motor assembly 18 also has a variable speed drive which can be adapted accordingly to ensure optimum operation of the apparatus 10. The variable speed at which the pump operates also enables the user to maintain the water levels on the outside of the apparatus 10 above level B as this is the only point where air can enter the system. The closed system mentioned above will be maintained in this instance until water in the surrounding sand body 20 is depleted for the time being. On the other hand, the water level inside the casing 12, may drop to below level A, but must be maintained above the level of the pump inlet and motor assembly 18 to avoid air-intake into the pump and motor assembly 18 causing operation of the pump and motor to stop.

As an example of the operation of the apparatus 10, upon commencement of the pumping action, the water table is at a level indicated by broken line A (static level). Only a slight drop in this level within the apparatus will occur when the apparatus is operated due to the filtration of water into the infiltration element 14. When the water in the surrounding sand body 20 is becoming depleted, or the extraction rate is too high, in other words when there is over-extraction of water, the level will drop to below level B as indicated by line y in figure 1 , causing the pump and motor assembly 18 to switch off and no further extraction of water is hence possible.

As mentioned above, for the apparatus 10 to function, the water level outside the casing 12 will have to be above the level B. It is only when the water level drops to below this level that air enters the closed system and consequently forces the pump and motor assembly 18 to switch off indicating that the water in the surrounding sand body 20 is depleted or that there is over-extraction of water at that particular time. In this sense, the variable speed of the pump motor 18 is particularly useful as mentioned in that the filtration rate into the apparatus 10 can be adapted in accordance with the various water levels.

The invention further extends to the provision of a plurality of air-release valves (not shown) along the casing 12 which allow for the release of air which may be present within the closed system.

These valves may be mechanically operated, such as the known spring- type valves, or may be electronically operated in accordance with the necessary suitable pressure sensor associated therewith. The installation and operation of these components will be within the competence of a person skilled in the art.

Periodic cleaning of the infiltration element 14 can be achieved by reverse washing or“flushing”, that is pumping in the reverse direction - in other words in the direction of the infiltration element 14 - so as to wash water outwards through the infiltration element 14.

In addition, chemical dosing of the infiltration element 14 is also possible by flushing suitable chemicals, such as algaecides and fungicides, through the infiltration element 14 to improve cleaning thereof whilst still maintaining water which is safe for use. Optimum conditions will be represented by comparatively clean large grained river sand where, for example, water is to be pumped from a dry river bed. It will be understood that the invention may be varied without departing from the scope of the invention.

For example, in the second embodiment shown in figure 2, it is possible to limit the length of the casing 12 to not extend upwards right up to the surface of the sand, but merely to a position just above the pump and motor assembly 18 being flanged and bolted as shown. In this instance, it is important to note that the delivery pipe 16 is also water-impermeable to maintain the closed system of the apparatus 10 as described. In addition, the third embodiment of figure 3 shows that the casing 12 can even extend up to above the surface. In figure 4, however, the casing 12 extends only to pump portion (18A) of the pump and motor assembly 18 such that the pump inlet and motor (18B) is sealed in the casing 12 to maintain the closed system required for operation of the apparatus 10 as described above. In this embodiment, the delivery pipe 16 is not housed inside the casing 12, but still impermeable to water to maintain the closed system. Furthermore, as shown diagrammatically in figure 5, the invention also provides for a plurality of infiltration elements 14 to be provided along the length of the apparatus 10. This is particularly useful where the geography of the particular area provides for layers of low permeability 32 between layers of sand bodies 20 rich in water.

Also shown in figures 1 , 2 and 4, the components, save for the outlet 22 are located underneath the sand surface to protect the components from outside elements such as wind, water and other debris, and in particular provides protection against flash flooding which is usually associated with river beds. This also avoids the requirement of building a suitable protective housing or similar structure for the components above the surface. The negative pressure of the pump and motor assembly 18 is particularly useful in that it allows a suction power to the water thereby expediting filtration of water through the infiltration element/s. The inventor has shown that extraction of water is much improved over apparatuses that do not utilizing negative pressure and relying on filtration only. A variable speed motor is furthermore useful in cases where highly variable static water levels are present in the surrounding sand body 20. However, a fixed speed motor (not shown) may also be utilized if water stability is present and where a cheaper apparatus is desired. In addition, as the effectiveness of water extraction is increased by the invention, the infiltration element/s can have a smaller surface area in comparison with the known apparatuses. A yet further advantage of the smaller infiltration element/s 14 is that the effectiveness of the flushing, whether with or without chemicals, is improved by effectively providing a concentrated flow of water through the smaller outlet area of the infiltration element/s 14. It will also be understood that the term“infiltration element” is not confined.

Any suitable filter, stacked ring filter, screen or slotted conduit which allows filtration of water into the delivery pipe may be provided without departing from the scope of the invention. The apparatus 10 may also be provided with any means to close off the components. For example, a suitable lid may be sealed to the casing with any suitable chemical adhesive.

It is accordingly asserted that the disadvantages of the known apparatuses for extracting underground water is alleviated or at least partially overcome. It will be appreciated by those skilled in the art that the invention is not limited to the precise details as described herein and that many variations are possible without departing from the spirit and scope of the invention as illustrated and exemplified.

The description above is presented in the cause of providing what is believed to be the most useful and readily understandable description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The words used here should be interpreted as words of description rather than words of limitation.

Claims

An apparatus for underground water extraction, comprising

a single continuously open-ended casing;

an infiltration element for underground water, connected to an operatively lower end of the casing which operatively permits water to enter the casing;

a lid on the upper end of the casing to seal the casing;

a pump and motor assembly for operatively displacing water from the infiltration element to a delivery pipe;

a sealed connection on the lid to operatively seal at least the pump inlet of the pump and motor assembly inside the casing;

2. An apparatus for underground water extraction as claimed in claim 1 , wherein the infiltration element comprises of any one or more of the group consisting of a stack of filter rings, a screen, a slotted conduit.

3. An apparatus for underground water extraction as claimed in claim 1 or 2, wherein the casing is sealed with the lid at its top by matching flanges of the casing and lid; by complimentary screw-threads on the casing and the lid; or by chemical adhesive between the casing and the lid, to create negative pressure inside the casing when operative; and wherein the lid has an opening to which the pump of the motor and pump assembly or the delivery pipe is connected and tightly sealed.

4. An apparatus for underground water extraction as claimed in any one of the preceding claims, which includes at least one air-release valve proximate the upper end of the casing or on the lid.

5. An apparatus for underground water extraction as claimed in claim 4, wherein the air-release valve is a mechanical or an electronically operated valve.

6. An apparatus for underground water extraction as claimed in any one of the preceding claims, wherein the motor of the pump and motor assembly is a fixed speed motor or a variable speed motor.

7. An apparatus for underground water extraction as claimed in any one of the preceding claims, wherein the pump and motor assembly is configured to permit flushing of the infiltration element.

8. An apparatus for underground water extraction as claimed in claim 7, wherein the flushing of the infiltration element includes flushing with water and/or chemicals.

9. An apparatus for underground water extraction as claimed in any one of the preceding claims, which includes a plurality of separate infiltration elements provided along the casing.

10. An apparatus for underground water extraction as claimed in any one of the preceding claims, which is operatively installed such that all components except an end of the delivery pipe is located below the ground surface.

1 1. A method of extracting underground water including the steps of installing an apparatus as claimed in any one of claims 1 to 10 such that at least the pump inlet of the pump and motor assembly and infiltration element are located within an underground water-bearing body; and actuating the motor and pump assembly to provide negative pressure such that filtration of water through the infiltration element into the delivery pipe is accelerated.

12. An apparatus for underground water extraction, substantially as herein described and exemplified and/or described with reference to the accompanying figures.

13. A method of extracting underground water, substantially as herein described and exemplified and/or described with reference to the accompanying figures.