GB2523845A - Equipment for preparing potable water - Google Patents

Abstract

Equipment 10 for preparing potable water comprises a treatment vessel 11 for water tobe treated and a microwave generator 13 arranged externally of the vessel and operable todirect microwave radiation into the vessel for microbiocidal treatment of the water therein by heating. A stirrer 14 agitates the water undergoing treatment in the treatment vessel so as to homogenise the water temperature. A storage vessel 12 stores disinfected water from the treatment vessel. The equipment includes a feed system 18, 19, 22 and 23 for feeding water to the treatment vessel in successive batches for batch-by-batch treatment and transferring each treated batch to the storage vessel. Preferably, the stirrer comprises an impeller and may be rotatable by an electromagnetic field. Suitably, an electromagnetic field generator 15 is arranged externally of the treatment vessel and is operable to generate an electromagnetic field which penetrates into the interior of the treatment vessel. A first valve 22 may control the flow of water through an inlet 18 into the treatment vessel, whilst a second valve 23 can control flow of water through an outlet 19 from the treatment vessel. Preferably, the storage vessel has an air vent 17.

Description

I

EQUIPMENT FOR PREPARING POTABLE WATER

The present invention relates to equipment for preparing potable water.

In many geographical locations in the modern world the availability of potable water is still a significant problem. Even when rainfall, wells, rivers, streams and other natural sources of water ensure a sufficient supply of water, micro-organism contamination (bacterial, viral and other) by various media including animal waste often gives rise to a risk to health which renders the water undrinkable. A wide variety of purification equipment exists to treat water to eliminate contamination, but most known equipment, particularly that on a smaller scale and suitable for use in domestic situations or otherwise for a few individuals, suffers from compromises with respect to efficacy on the one hand and economy of construction and operation on the other hand.

It is therefore the object of the present invention to provide water treatment equipment, especiaUy equipment suitable for domestic or small-scale use, which is of relatively simple construction, is economic to operate and is effective for elimination of harmful micro-organism contamination of the water.

Other objects and advantages of the invention will be apparent from the following

description.

According to the present invention there is provided equipment for preparing potable water comprising a treatment vessel for water to be treated microwave generating means arranged at the treatment vessel externally thereof and operable to direct microwave radiation into the interior of the treatment vessel for microbiocidal treatment of water therein by heating, agitation means for agitation of water undergoing treatment in the treatment vessel so as to at least reduce non-uniformity of the temperature of the water, a storage vessel for storage of water after treatment in the treatment vessel and feed means for feeding water to the treatment vessel in successive batches for batch-by-batch treatment and for feeding each treated batch of water to the storage vessel.

Whereas many examples of prior art apparatus operate on the basis of continuous treatment of water, which can have a limiting effect on the scope for thorough microbiocidal action on the water, the present invention functions with batchwise treatment and employs microwave radiation capable of superheating the water and thereby providing a high level of confidence with regard to mortality of all harmful micro-organisms in each batch. In particular, the residence time of each batch in the treatment vessel during microwave-induced heating can be selected to be of such length as to ensure complete mortality without operating the microwave generating means, and thereby consuming energy, longer than necessary. Each treated batch can then be discharged into the storage vessel, from where it can be tapped by suitable means for use especially, but not exclusively, as drinking water. The equipment is then ready for treatment of a further batch either directly after the discharge into the storage vessel or, if desired, at a later point in time. Use of microwave excitation by way of microwave generating means located externally of the treatment vessel eliminates the need for a heating arrangement within the vessel and thus removes concerns with respect to calcification and consequent progressive reduction in heat output. In addition, agitation of water undergoing treatment promotes temperature homogenisation and thus more effective microbiocidal action for a given operating time of the microwave generating means. Furthermore, microwave irradiation serves to heat up the treatment vessel walls, thereby killing any micro-organisms that may be located in micro-crevices or cracks within the treatment vessel walls, thus dispensing with any need to employ microbiocidal chemicals thereon and/or therein. Collectively, the stated features of the equipment provide an advantageous combination of economy and efficiency by comparison with other examples of equipment employed for the same task.

For preference, the equipment comprises control means for controlling the microwave generating means to operate for a period of time predetermined to be sufficient for effective microbiocidal action on a batch of water of given volume in the treatment vessel.

The operating duration of the microwave generating means can thus be controlled for an optimum balance between the effectiveness of the heating and the consumption of operating energy by the microwave generating means. Such control means can, for example, include a programmable timer which can be adjusted to take account of different batch volumes, selective operation at times of reduced grid supply costs and other factors connected with the duration and timing of treatment.

The agitation means preferably comprises a stirrer movable to stir water in the vessel, thus a stirrer which mechanically agitates as distinct from agitation by, for example, flow currents induced by other methods. Such a stirrer represents a simple and economic means of agitation. However, it can be advantageous if the stirrer is movable, preferably rotatable, by an electromagnetic field, especially through provision of electromagnetic field generating means arranged externally of the treatment vessel and operable to generate an electromagnetic field penetrating into the interior of the treatment vessel. In that case, the stirrer can comprise an impeller supportable by the field. This arrangement makes it possible to move the stirrer by force transmitted to the stirrer other than by way of a physical connection, so that the wall of the treatment vessel does not need to be penetrated by a drive shaft liable to give rise to sealing issues. However, it is equally possible for the stirrer to be mechanically drivable by drive means arranged externally of the treatment vessel, subject only to the need to ensure tightness in any gland which seals a coupling between the drive means and the stirrer.

For preference, the feed means comprises inlet means for inflow of water into the treatment vessel and outlet/inlet means for outflow of water from the treatment vessel and inflow of that water into the storage vessel. The inlet means and outlet/inlet means can be conveniently provided by pipes and/or hoses in conjunction with inlet and outlet ports at the respective vessels. Feed control can be provided by, for example, first valve means for controlling flow of water through the inlet means and second valve means for controlling flow of water through the outflowlinflow means. Such valve means can be operated manually or automatically, for example by way of the afore-mentioned control means for controlling the microwave generating means. In the case of automatic operation the valve means are, for example, electrical, electromechanical or electromagnetic valves. Automatic operation can be particularly advantageous if it is carried out under time control interlinked with the microwave generating means and, for example, in response to drainage of treated water from the storage vessel, so that the treatment vessel can be refilled with water in readiness for treatment of a replenishing batch.

It may be advantageous if the equipment comprises cooling means for the cooling of water flowing through the outflow/inflow means, so that heated water passing to the storage vessel for storage is cooled down to a temperature suitable for use without undue delay until natural heat loss occurs. Such cooling means can comprise a heat exchanger for recovery of heat to be made available for other purposes, including heating of part of a water supply not specifically intended for drinking, such as a domestic hot water system or domestic room heating system.

For preference, the storage vessel is provided with air venting means for venting air from the interior of the storage vessel. The venting means thus allow ingress and egress of treated water to be accompanied by corresponding displacement of air. In addition, the equipment can include an expansion vessel for accepting water displaced from the treatment vessel by expansion, which may be particularly advantageous in the case of superheating of the water being treated.

The capacities of the treatment vessel and storage vessel can be freely selectable, but in a preferred embodiment the capacity of the storage vessel is at least five times that of the treatment. This relationship enables the storage vessel to be large enough to store usefully large quantities of treated water, but the treatment vessel to be small enough for heating and agitation of water in the treatment vessel to be achievable without requiring an unduly large heating and agitating system liable to consume greater amounts of operating energy.

A preferred embodiment will now be more particularly described by way of example with reference to the accompanying drawing, the single figure of which is a schematic diagram of equipment embodying the invention.

Referring now to the drawing there is shown equipment 10 for preparing potable water, especially by treatment of water from a potentially contaminated natural or other source to eradicate bacterial contamination. The equipment is particularly suitable for smaller-scale domestic or related use, particularly in geographical locations without a natural or piped clean water supply, but can equally well be constructed on a larger scale for commercial/industrial application or as mobile facility. In the last-mentioned case the equipment can be set up in areas with a drinking water supply need and draw on available sources of unpurified water.

The equipment 10 comprises a treatment vessel 11 for batchwise treatment of water and a storage vessel 12 for storage of the treated water. Each vessel is preferably a container of any suitable shape preferably moulded from a suitable plastics material which is capable of tolerating microwave radiation and which is inert in relation to the water. Other container materials, including coated metal or metal alloy, are also possible. The capacity of the treatment vessel 11 is, for preference, at least five times that of the storage vessel 12. By way of arbitrary example the capacity of the former can be 2 litres and that of the latter 15 to 20 litres.

Water in the interior of the treatment vessel 11 is treated by way of a microwave heater 13, which is arranged externally of the vessel 11, in particular on a side wall of the vessel, and operable to direct microwave radiation into the interior of the vessel so as to heat, especially superheat, the water content and thereby produce a microbiodical action on micro-organisms in the water. The microbiocidal action is enhanced by temperature homogenisation of the water by a stirrer in the former of a rotary impeller 14 which functions to agitate the water and thus set the water into a circulatory flow or turbulent motion. Formation of water dead zones or cold spots can be prevented by the agitation.

In this embodiment, the impeller 14 is a floating impeller supported and set into rotation by an electromagnetic field generated by an electromagnetic field generator 15 arranged externally of the treatment vessel 11, for example mounted on the outside of a base wall of the vessel, and operable to generate a field oriented to penetrate into the interior of the vessel. Although the impeller is at liberty to float it can, however, be constrained or caged so as not to be displaced, or so as to be displaced only by a limited amount, by inflowing water. It is also possible to employ a stirrer mechanically coupled to and driven by an external drive unit, such as an electric motor.

The equipment can include an expansion tank 16 connected with the treatment vessel 11 and arranged to accept water displaced from the vessel due to expansion when the water content of the vessel is heated. Similarly, the storage vessel 12 is provided with a valve-controlled vent 17 for permitting air to escape from and enter the vessel 12 in response to, respectively, movement of water into and movement of water out of the vessel.

The principal components of the equipment 10 are completed by a feed system for supply of water to the treatment vessel 11, transfer of water from the vessel 11 to the storage vessel 12 and discharge of water from the storage vessel. As shown in highly diagrammatic fom, in the figure, the feed system comprises an inlet pipe 18 for feed of water to the vessel 11, a transfer pipe 19 for transfer of water from the vessel 11 to the vessel 12 and an outlet pipe 20 for discharge of water from the vessel 20. The inlet pipe 18 is connectible with a source of water to be treated and with an inlet of the vessel 11 and preferably includes a filter 21 for removal o entrained solids from water conducted through the pipe 18. The water fed via the pipe 18 to the vessel 11 is supplied in batches so that treatment on a batchwise basis will be carried out. Control of the water supply via the pipe 18 is by way of an integrated electromagnetic inflow valve 22 controlled to admit a predetermined volume of water into the vessel 11. The quantity can be predetermined by way of time control of the valve 22 based on a given flow rate or by a level sensor of any suitable form in or associated with the vessel.

The transfer pipe 19 is connected with an outlet of the vessel 11 and an inlet of the vessel 12 and includes an electromagnetic outflow/inflow valve 24 operable to allow water to flow out of the vessel 11 and into the vessel 12. The outflow/inflow also takes place in batches, in particular discharge of the entire content of the vessel 11 and transfer of the entire discharged quantity into the vessel 12. The transfer pipe 19 also includes an in-line cooler 24 for cooling the transferred water so as to at least reduce its superheated state. The cooler 24 can optionally be structured as a heat exchanger to recover useful heat from the cooling process.

The outlet pipe 20 is connected with an outlet of the storage vessel 12 and includes an electric pump 25 which can be operated when required to extract treated water from the vessel 12 and supply it to a point of use.

The operation of the heater 13, generator 15, valves 22 and 23 and pump 25 is controlled by way of an electrical or electronic control unit 26, which is shown mounted on the storage vessel 12 and electrically connected by control lines to the components it controls.

The control unit 26 can, however, be located in any convenient location. The control unit 26 can function to control, in particular, the heater, generator and valves so that batchwise treatment of water and transfer of treated batches for storage takes place on a programmed basis with automatic control of water flow, heating and stirring in accordance with correlated parameters.

Although the heater 13 is necessarily electrically operated and the stirrer is preferably electrically operated, electrical operation of the valves and pump is not essential and these can, for example, be constructed to be alternatively or additionally mechanically operated should this be desirable for any reason.

The equipment 10 hereinbefore described enables preparation of potable water on a batch-by-batch basis so that the water can be subjected to focussed microbiocidal action to achieve a complete mortality of a population of micro-organisms, in particular through economic use of microwave superheating and agitation of the water for temperature homogenisation of the treated water.

Claims (14)

1. BCLAIMS1. Equipment for preparing potable water comprising a treatment vessel for water to be treated, microwave generating means arranged at the treatment vessel externally thereof and operable to direct microwave radiation into the interior of the treatment vessel for microbiocidal treatment of water therein by heating, agitation means for agitation of water undergoing treatment in the treatment vessel so as to at least reduce non-uniformity of the temperature of the water, a storage vessel for storage of water after treatment in the treatment vessel and feed means for feeding water to the treatment vessel in successive batches for batch-by-batch treatment and for feeding each treated batch of water to the storage vessel.
2. 2. Equipment according to claim 1, comprising control means for controlling the microwave generating means to operate for a period of time predetermined to be sufficient for effective microbiocidal action on a batch of water of given volume in the treatment vessel.
3. 3. Equipment according to claim 1 or claim 2, wherein the agitation means comprises a stirrer movable to stir water in the treatment vessel.
4. 4. Equipment according to claim 3, wherein the stirrer is movable by anelectromagnetic field.
5. 5. Equipment according to claim 4, wherein the stirrer is rotatable by the field.
6. 6. Equipment according to claim 4 or claim 5, comprising electromagnetic field generating means arranged externally of the treatment vessel and operable to generate an electromagnetic field penetrating into the interior of the treatment vessel.
7. 7. Equipment according to claim 6, wherein the stirrer comprises an impellersupportable by the field.
8. 8. Equipment according to claim 3, wherein the stirrer is mechanically drivable by drive means arranged externally of the treatment vessel.
9. 9. Equipment according to any one of the preceding claims, wherein the feed means comprises inlet means for inflow of water into the treatment vessel and outlet/inlet means for outflow of water from the treatment vessel and inflow of that water into the storage vessel.
10. 10. Equipment according to claim 9, comprising first valve means for controlling flow of water through the inlet means and second valve means for controlling flow of water through the outflow/inflow means.
11. 11. Equipment according to claim 9 or claim 10, comprising cooling means for the cooling of water flowing through the outflow/inflow means.
12. 12. Equipment according to any one of the preceding claims, wherein the storage vessel is provided with air venting means for venting air from the interior of the storage vessel.
13. 13. Equipment according to any one of the preceding claims, comprising an expansion vessel for accepting water displaced from the treatment vessel by expansion.
14. 14. Equipment according to any one of the preceding claims, wherein the capacity of the storage vessel is at least five times that of the treatment vessel.