GB2277883A - Combined heating and purification of water - Google Patents

Abstract

A method of purifying water is shown in which a portion of the heated water contained in a storage tank for heated water is further heated to boiling point, the steam generated is cooled by passage through a condensing system in thermal contact with the heated water so as to provide further heat to the stored water. The condensate is collected and, preferably, cooled. Apparatus for performing the method uses a water storage container adapted to be supplied with and store heated water and which includes a steam generator arranged to be supplied with heated water from the storage container. Condensing means receives steam from the generator and transfers the thermal energy produced by condensation of the steam to the heated water in the container. Collection means receives and stores the water formed by condensation of the steam.

Description

COMBINED HEATING AND PURIFICATION OF WATER This invention relates to a combined method of heating water and providing pure water by distillation.

Water supplies to commercial and domestic premises are frequently contaminated by the presence of dissolved inorganic compounds and organic matter such as bacteria and nematode worms. The exact nature of the contaminants will depend upon the source of the water and the subsequent treatment by the water supplier which may reduce some contaminants but increase others. The standards of purity considered adequate by water supply companies fall short of that required by many adult members of the public and may be dangerous for use by the infirm or infants.

As a result of this perceived danger it is common for bottled water from various sources to be purchased for drinking or for simple purifying devices to be used in homes and offices. Bottled water may not in fact be uncontaminated and usually has an appreciable mineral content together with a mixture of dissolved gases.

The domestic purification devices currently available may remove some inorganic compounds and filter or absorb some of the biological matter but none provide pure, unadulterated water. More elaborate methods of water purification exist however their cost and complexity prevents their use in a domestic environment.

According to the present invention there is provided a method of purifying water wherein a portion of the heated water contained in a storage tank for heated water is further heated to boiling point, the steam generated is cooled by passage through a condensing system in thermal contact with said heated water so as to further heat the stored water and the condensate is collected and, preferably, cooled.

There is further provided apparatus for the production of pure water comprising a water storage container adapted to be supplied with and store heated water, characterised in that it further comprises a steam generator arranged to be supplied with heated water from said storage container, condensing means arranged to receive steam from said generator and transfer the thermal energy produced by condensation of said steam to said heated water and collection means adapted to receive and store the water formed by condesation of said steam.

The water storage container adapted to store heated water is preferably a closed cylindrical container. The water within the container may be heated directly by a heating coil supplied with heated water from an external heater or directly heated by an electrically operated immersion heater or other known means. Alternatively the container may be directly supplied from a source of heated water.

Cylindrical water storage containers of this type are widely available in a variety of volumetric capacities for use in domestic and commercial premises.

Water storage containers are conventionally fabricated from a corrosion resistant material such as copper. Other corrosion resistant materials may be used such as stainless steel or titanium. Similarly the associated pipework and the internal heating coils and condensers are made of the same materials. In order to conserve energy the containers are surrounded with a thick layer of a thermally insulating material such as glass wool or polyurethane foam.

The steam generator is preferably supplied with heated water from the storage container at a constant pressure by means of a constant head device such as a reservoir tank with a float operated supply valve or similar device. The generator itself is preferably a sealed enclosure containing a heating element. The heating element is preferably an electrically insulated and sealed case containing a resistance element heated by the passage of an electric current, e.g. a so-called immersion heater. Other forms of heater may be used such as gas or solar heaters. The heating element is preferably used in conjunction with control systems of known type which prevent overheating of the element in the absence of water, remove power when excess pressure builds up and when other hazardous situations arise. Facilities are necessary to enable the removal of the inevitable deposits of scale which accumulated during use. Such scale may be removed by disassembly and physical cleaning or providing a by-pass route for water to enable the generator assembly to be flushed out from time to time.

The condenser may take any known form but is preferably in the form of a helix made from a thermally conducting metal pipe. The helix is immersed in the fluid contents of the storage tank so that the thermal energy released by condesation of the steam entering it and the inherent heat energy are transferred to the tank contents. The condensate flows under the action of gravity into a pure water supply tank preferably located beneath the storage tank. The condesnate is further cooled in a preferred embodiment by by the inclusion of baffle plates within the pure water tank which are thermally connected to the base of the storage tank. Heat energy is transferred by this means through the base of the storage tank to the cooler portion of its contents.

The contents of the pure water storage tank may be consumed directly or used in food preparation and for other purposes with confidence of its purity. Alternatively the pure water may be aerated, carbonated and/or have inorganic slats added to enable it to mimic naturally occurring mineral waters.

The method of purifying water and the apparatus for the production of pure water according to the invention provides a convenient regular supply of pure water for doemstic use with the minimum of complexity. Furthermore by virtue of its association with existing domestic hot water supply systems the invention results in little extra use of energy.

In order that the invention may be clearly understood it will now be described with reference to the accompanying drawings in which: Figure 1 is cross-sectional view in a vertical plane of apparatus for the production of pure water according to the invention, Figure 2 is a cross-sectional view in a horizontal plane of the apparatus shown in Figure 1, and Figure 3 is a plan view of a baffle-type condenser for use in the apparatus shown in Figures 1 and 2.

Apparatus for the production of pure water according to the invention, see Figure 1, consists of a cylinder 1 adapted to contain water. The cylinder 1 receives unheated water through inlet port 2 from a constant head source such as a storage tank not shown, in conventional manner. Outlet port 3 at the head of the cylinder provides an exit for the contents of the cylinder 1. A heating coil 4, fabricated from a thermally conducting material, has a primary flow inlet 5 and a primary return outlet 6 adapted to receive a flow of heated water from a water heater, not shown, in conventional manner.

The upper portion of the cylinder 1 carries a constant head tank 7 supplied by a float operated valve 8 supplied with heated water from the cylinder 1. The tank 7 is connected to a steam generator 9 by means of a pipe 10. The steam generator 9 includes an electrically heated element 11 immersed in the heated water supplied to the generator from the tank 7. A condensing coil 12 is located within the cylinder 1 and has a steam inlet 13 adapted to receive steam from the generator 9 and a condensate outlet 14.

The outlet 14 is located in a pure water supply tank 15 containing a series of baffles 16 which assist cooling of the condensate. The tank 15 has a air relief port 17 and a supply outlet 18.

In use the steam generator 9 provides a steady supply of steam by evaporation of already water which is raised to its boiling point by the heated element 11. The steam leaves the generator 9 and flows through the condensing coil 12 where it is cooled by the water stored in the tank 1. The condesate at a temperature equal to or slightly higher than the average temperature of the water in the tank 1 enters the pure water storage tank 15. The contents of the tank 15 are further cooled by heat conducted by the baffle plates 16 through the base of the tank 1 to the coolest part of its contents.

Control means, not shown, may be used to switch the heated element 11 in conjunction with various temperature, level, pressure and flow sensors. By this means steam generation can be stopped when the tank 15 is full, when the water supply to the generator 9 fails or the pressure rises excessively. Further the control means may be used to stop the generation of steam when the heating effect by the condenser 12 raises the contents of the tank 1 to a temperature in excess of a preset limit. As well as control of the energy supplied to the element 11 the control means may control the flow of heating water into the coil 4 and/or control any immersion heater that may be present in the cylinder 1.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims (18)

1. A method of purifying water wherein a portion of the heated water contained in a storage tank for heated water is further heated to boiling point, the steam generated is cooled by passage through a condensing system in thermal contact with said heated water so as to further heat the stored water and the condensate is collected and, preferably, cooled.

2. Apparatus for the production of pure water comprising a water storage container adapted to be supplied with and store heated water, characterised in that it further comprises a steam generator arranged to be supplied with heated water from said storage container, condensing means arranged to receive steam from said generator and transfer the thermal energy produced by condensation of said steam to said heated water and collection means adapted to receive and store the water formed by condesation of said steam.

3. Apparatus as claimed in claim 2, characterised in that the water storage container adapted to store heated water is a closed cylindrical container.

4. Apparatus as claimed in claim 2 or claim 3, characterised in that the water within the container is heated directly by a heating coil supplied with heated water from an external heater.

5. Apparatus as claimed in claim 2 or claim 3, characterised in that the water within the container is directly heated by an electrically operated immersion heater.

6. Apparatus as claimed in claim 2 or claim 3, characterised in that the water within the container is directly supplied from a source of heated water.

7. Apparatus as claimed in any of the preceding claims, characterised in that the water storage container is fabricated from copper, stainless steel or titanium.

8. Apparatus as claimed in any of the preceding claims, characterised in that the steam generator is supplied with heated water from the storage container at a constant pressure.

9. Apparatus as claimed in any of the preceding claims, characterised in that the steam generator comprises a sealed enclosure containing a heating element.

10. Apparatus as claimed in claim 9, characterised in that the heating element is an electrically insulated and sealed case containing a resistance element heated by the passage of an electric current.

11. Apparatus as claimed in claim 8 or claim 9, charactised in that the heating element is has associated control systems to prevent overheating of the element in the absence of water and to remove power when the pressure in the sealed enclosure reaches a preset limit.

12. Apparatus as claimed in any of the preceding claims, characterised in that the condensing means is a helix made from a thermally conducting metal pipe immersed in the fluid contents of the storage tank.

13. Apparatus as claimed in any of the preceding claims, characterised in that the condensate from the condensing means flows under the action of gravity into a collection tank located beneath the storage tank.

14. Apparatus as claimed in any of the preceding claims, characterised in that the condensate from the condensing means flows through secondary cooling means formed by baffle plates within the storage tank which are thermally connected to the base of the storage tank.

15. Methods of purifying water as claimed in claim 1 and as herein described.

16. Methods of purifying water as herein described with reference to the accompanying drawings.

17. Apparatus for the production of pure water as claimed in claim 2 and as herein described.

18. Apparatus for the production of pure water as herein described with reference to the accompanying drawings.