GB2372801A

GB2372801A - Water storage container

Info

Publication number: GB2372801A
Application number: GB0204522A
Authority: GB
Inventors: Islwyn Uhland Watkins; Stephen Henry Colclough
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-28
Filing date: 2002-02-26
Publication date: 2002-09-04
Also published as: WO2002068880A3; GB0105058D0; AU2002233550A1; WO2002068880A2; GB0204522D0

Abstract

A liquid heating and storage system comprising means for heating cold water, container means for storing the heated water and outlet means which extends from a position close to the top of the container means through an opening at or adjacent to the bottom of the container means. The system comprises a cylinder (10) surrounded by an insulation layer (14) and mounted on a base plate (16) by means of suitable seals and fixings. All connections and appendages to the container are routed through the base plate (16) so that there is little or no heat loss through the insulation layer (14) surrounding the cylinder (10). A heater (18) is provided within the cylinder (10) to heat the water contained therein. Hot water is delivered from the container to an insulated tube (20) which extends vertically from an opening in the base plate (16), the inlet of the insulated tube (20) being positioned near the top of the container close to the domed portion (12). The system may have flow regulating means (26), an expansion chamber (24), temperature sensing means (42), or temperature limiting/relief valve means (40).

Description

WATER STORAGE CONTAINER

This invention relates to a water storage container and, in particular, to a container for storage of potable and non potable water for domestic, commercial and industrial usage.

A conventional water heating and storage system comprises a copper, generally cylindrical container having a heater therein. Inlet means are provided close to the bottom of the container to introduce cold water into it, which is heated by the heater, and the hot water is drawn off on demand via an outlet pipe which extends upwardly from an opening in the top of the container. Cold water entering the container at the bottom thereof displaces the hot water and pushes it upwardly in the container.

The above-described conventional system, although widely used, has a number of disadvantages associated with it.

Firstly, to avoid excessive heat loss, the copper container must be lagged or shrouded with an insulating cover or jacket. However, because of the outlet pipe at the top of the container, the container cannot be completely covered and substantial heat can be lost through the hole in the jacket which must be provided to accommodate it. Another disadvantage is that as cold water enters the container through the inlet at the bottom, substantial turbulence may be created causing the cold water entering the container to mix with the hot water already contained therein, thereby cooling it. As a result, water that has already been

heated to the required temperature once must be heated again.

These disadvantages, among others, mean that the conventional water storage container is relatively inefficient, especially with regard to energy usage.

We have now devised an arrangement which overcomes the problems outlined above, and provides a water storage container which is cost effective and efficient. In accordance with a first aspect of the present invention, there is provided a liquid heating and storage system comprising means for heating cold water, container means for storing the heated water and outlet means which extends from a position close to the top of the container means through an opening at or adjacent to the bottom of the container means.

Because the hot water outlet extends out of the container at the bottom, the upper body of the container can be completely covered by an insulating layer, thereby substantially reducing heat loss from the container. The container is preferably a cylinder, preferably of reinforced plastics material, aluminium, enamel steel, copper or the like. Inlet means are beneficially provided to introduce cold water into the container, in which case heating means to heat the cold water are also provided within the container. The heating means may be an electric heater, a directly-driven combustion heater, an indirect coil from another heating source, e. g. hydraulic coil, or

any other suitable heating means.

Conventionally, although more efficient, cost-effective and convenient than other types of heater, electric heaters are not generally used in water heating and storage systems because the high temperature energy interface between the electric element and the cold water causes a chemical reaction which causes minerals from the water to be deposited over time on the element which substantially reduces its efficiency and eventually its life.

In accordance with a second aspect of the present invention, there is provided an electric heater for heating liquid, the heater comprising a conductive element housed within a heat conductive member containing a heat conductive fluid.

The heat conductive fluid is preferably oil and the heat conductive member is beneficially coil-shaped and preferably metal. Thus, the element is effectively shielded from the water by the fluid-filled coil, and the temperature interface between the outer surface of the coil and the water to be heated is too low for the abovedescribed mineral deposits to occur (the transfer of heat from the element to the outer surface of the coil via the oil causes a reduction in heat energy) so that the life of the electric heater is substantially increased.

In accordance with a third aspect of the present invention, there is provided a liquid heating and storage system,

comprising container means, means for introducing cold liquid into said container means, and means for heating the cold liquid, the means for introducing the cold liquid into the container comprising flow regulating means having an inlet of a first diameter for introducing cold liquid into the flow regulating means, and a plurality of outlets each having a diameter less than said first diameter but having a collective diameter greater than said first diameter.

The above-defined flow regulating means substantially reduces the velocity of flow of the incoming liquid such that it enters the container with little or no turbulence, i. e. laminar flow. The inlet to the flow regulating means preferably comprises a pipe or tube which extends upwardly into the container means from an opening in the bottom of the container.

The liquid heating and storage system of the present invention preferably comprises excessive temperature relief means and/or excessive pressure relief means. The temperature and or pressure relief means preferably comprise one or more valves attached to a respective tube which extends upwardly into the container means from an opening in the bottom of the container means.

In accordance with a fourth aspect of the present invention, there is provided a liquid heating and storage system, comprising a generally cylindrical container which is closed at one end, the other end being covered by a removable base plate, the system further comprising inlet

means for introducing cold liquid into said container, means for heating said liquid and outlet means for drawing heated liquid from the container, the inlet means, outlet means and heater supply means extending into the container through a respective opening in the base plate and being connected thereto, such that when said base plate is removed from the container, the inlet means, outlet means and heating means are also removed therefrom.

The base plate is preferably on the bottom of the container, and the container is preferably provided with a base stand to support it above the ground, thereby leaving room for the inlet means, outlet means and heater supply means extending therefrom and permitting easy access to the base plate for removal thereof.

In accordance with a fifth aspect of the present invention, there is provided a liquid heating and storage system, comprising means for heating liquid, means for storing the heated liquid, and elongate temperature sensing means contained within and extending along a substantial portion of the length of the storage means for detecting the temperature of liquid in the storage means at a plurality of different positions.

The temperature sensing means preferably includes or is connected to means for providing temperature readings in a format which allows the temperature profile of the storage means to be assessed. Means may also be provided for determining the quantity of heated liquid in the storage

means and for providing such information to local and/or remote decision making means.

According to a sixth aspect of the present invention, there is provided a liquid heating and storage system, comprising container means, inlet means for introducing cold liquid into the container means, means for heating the cold liquid within the container means, and outlet means for drawing at least some of the heated liquid out of the container means, the system further comprising an expansion chamber consisting of a contained airlock which is exposed to the contents of the container means, the air within the airlock being compressed in response to rising pressure within the container means.

In a conventional heating and storage system, excessive temperature relief is achieved by means of a temperature relief valve which is bolted to the top of the cylinder and is controlled by means of a probe which extends from the valve into the cylinder. We have now devised an improved arrangement and, in accordance with a seventh aspect of the present invention there is provided a liquid heating and storage system comprising means for heating cold water, container means for storing the heated water and means for relieving the temperature within the container means if it exceeds a predetermined level comprising temperature limiting/relief valve means which is exposed to and immersed in the heated water, preferably at or adjacent the top of the container means.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawing, in which: Figure 1 is a schematic cross-sectional view through a water heating and storage system according to a first exemplary embodiment of the invention; and Figures 2 to 4 are respectively schematic cross-sectional plan, side and plan views of a water heating and storage system according to a second exemplary embodiment of the invention.

Referring to Figure 1, a hot water storage container according to an exemplary embodiment of the present invention comprises a cylinder 10 which is closed at the top by a domed or spherical portion 12. The cylinder 10 may be copper, reinforced plastic or any other suitable material with an inner surface layer suitable for containing potable water. The cylinder 10 is surrounded by an insulation layer 14 which is contained within a skin having suitable mechanical strength and resistance to damage and external elements. The bottom of the cylinder 10 is covered by a removable base unit or plate 16 which is mechanically jointed to the cylinder 10 by means of seals, such as'0'rings or the like, and fixings, such as bolts or the like, thereby achieving the required pressure containment of the container. The container should ideally be capable of containing working pressures of 3-7 bar and test temperatures of 7-14 bar.

As shown, all connections and appendages to the container are routed through the base plate 16 so that there is little or no heat loss through the insulation layer 14 surrounding the cylinder 10. A heater 18 is provided within the cylinder 10 to heat the water contained therein. Hot water is delivered from the container through an insulated tube 20 which extends vertically from an opening in the base plate 16, the inlet of the insulated tube 20 being positioned near the top of the container close to the domed portion 12.

The heater 18 comprises an electric element housed within a sealed convection re-circulating metal coil containing a fluid, such as oil. Electrical power is supplied to the element via a supply line 22 which extends upwardly from an opening in the base plate 16 to the heater 18. When the element is supplied with power, it becomes hot and heats the oil circulating in the coil. Heat from the oil in the coil is then transferred to the water in the cylinder 10 to heat it. Thus, the oil efficiently transmits the high temperature energy at the metal/oil interface of the element to the lower temperature metal/water interface of the coil. It is well known that in appliances such as kettles, where an electrical element is used within a vessel to heat water contained therein, the element has a finite life because mineral deposits build up on it over time (due to the high temperature energy at the metal/water interface) until it is no longer effective in heating the water. However, in the heater used in this exemplary embodiment of the present invention, the element is

effectively shielded from the water in the cylinder 10 by the coil in which it is housed, and mineral deposits do not form on the outer surface of the coil because the temperature energy at the metal/water interface is reduced by the oil in the coil to a level below that at which the chemical reaction required to cause the mineral deposits occurs. Means (not shown) are provided to control and limit the fluid (oil) temperature within the heater 18 accordingly. Further, energy input control is provided by means of local and/or remote electronic switching devices, which energy input control takes account of demand, time, energy required and predicted usage.

Although a novel electric heater for use in this exemplary embodiment of the invention has been described in detail above, it will be appreciated that any suitable type of heating means may be used, such as a directly fired combustion system.

An expansion chamber 24 is provided within the cylinder 10 and a flow regulating member 26 is contained within the expansion chamber 24 for introducing cold water from the mains supply into the cylinder 10. The flow regulating member 26 comprises a dome-shaped tube 28, the ends of which are connected together by a horizontal tube 30. The outer wall of the horizontal tube 30 is provided with a plurality of spaced-apart apertures 32. Cold water enters the flow regulating member 26 via an inlet pipe 34 which extends upwardly from an opening in the base plate 16. Water from the inlet pipe 34 flows through the dome-shaped

tube 28 of the flow regulating member 26 to the horizontal tube 30 and from there flows downwardly into the cylinder 10 through the apertures 32.

As the cold water flows into the cylinder 10 it pushes the body of hot water already contained therein upwards. The apertures 32 through which the cold water enters the cylinder 10 together form a cold water inlet having a diameter substantially greater than that of the water inlet pipe 34. Thus, the velocity of the cold water flow is substantially reduced by the flow regulating member 26 before the cold water is introduced into the cylinder 10, thereby producing an effect known as'laminar flow', which means that the cold water is introduced into the cylinder 10 with little or no turbulence, thereby preventing mixing of the cold and hot water within the cylinder 10. As a result, the temperature of the previously-heated water is not reduced by the incoming cold water such that all of the hot water can be used. This greatly improves the efficiency of the arrangement because it avoids the need to re-heat water which has already been heated.

The expansion chamber 24 comprises a substantially cylindrical contained airlock which is effectively exposed to the water contained within the cylinder 10. The air captured within the airlock is compressed as a result of an increase of pressure within the cylinder 10, thereby enabling the pressure within the container to maintained within a predetermined range throughout the temperature limits of a normal heating cycle. The size of the

expansion chamber 24 is chosen to allow for all hydraulic expansion to be contained within specified limits inside the cylinder 10 throughout the temperature limits of a normal heating cycle, say 3 C-140 C. Thus, the expansion chamber 24 is effectively a'passive'component of the system which responds to the internal pressure within the cylinder 10.

The water heating and storage system of this exemplary embodiment of the present invention is further provided with means for relieving excessive pressure within the container. The excessive pressure relief is achieved in this embodiment by means of a pressure limiting/relief valve (not shown) fixed on a suitably sized tube 36 within the cylinder 10 such that it is exposed to and unimpeded by its contents. The tube 36 extends upwardly from an opening in the base plate 16.

The water heating and storage system of this exemplary embodiment of the present invention is also provided with means for relieving excessive temperature within the container. The excessive temperature relief is achieved in this embodiment by means of a mechanical high temperature limiting/relief valve 40 fixed to a suitably sized tube 38 within the cylinder 10 such that it exposed to and immersed in the contained storage water as near to the top of the cylinder 10 as is practical. Once again, the tube 38 extends upwardly from an opening in the base plate 16. In the event that the temperature of the contained storage water within the cylinder 10 exceeds a predetermined level,

the valve 40 opens to allow cold water to enter the cylinder 10 (through the tube 38) which displaces hot water and cools the contents of the cylinder 10.

An elongate temperature sensing device 42 extends upwardly within the cylinder 10 from an opening in the base plate 16 to a point around 25mm from the highest point of the container, thereby enabling temperatures to be detected at substantially all depths within the cylinder 10. These temperatures may be provided in a format which would permit the temperature profile of the container to be assessed, thereby enabling the quantity of hot water in the container to be determined by means of logic controllers. This information can be made available to local and/or remote decision making means (not shown). In one embodiment, such decision means may have defined therein a minimum quantity of hot water which it ensures is maintained at all times within the container. The system may be connected to the decision making means via the Internet.

Referring to Figures 2 to 4 of the drawings, a second exemplary embodiment of the invention comprises a main tank or cylinder 10 mounted on a base plate 16 via which the following services enter or leave the cylinder 10: Cold water fill 102 (from mains supply)-the cold water fill once again enters via a system designed to minimise turbulance and thereby avoids mixing the hot and cold water;

Hot water outlet 104 ; Heating coil or element 106 ; Temperature sensing device 108; High-pressure relief (not shown); High temperature relief 112; Drain 113.

At least one, and more preferably, two expansion tanks 114 are also provided and mounted on the base plate 16.

Connections 116,118 are provided between the interior of the cylinder 10 and the expansion tanks 114. There is no material barrier between the air/water interface within the expansion tanks 114. The expansion tanks 114 are provided to receive and store hot water from the cylinder 10 when the cylinder 10 is full. Means (not shown) are preferably provided to enable the cylinder 10 to be completely filled prior to water entering the expansion tank (s) 114, and the same or additional means (not shown) are preferably provided to prevent water from the expansion tank (s) 114 from entering the hot water area of the cylinder 10 at least while water is being drawn therefrom.

The manner in which the dimensions of the cylinder 10 and expansion tank (s) 114 may be calculated in one specific exemplary embodiment of the invention is shown below:

Tank Size Calculation Total required volume 211 ltrs 211000 cu cm Assuming the shape is a cylinder topped by a sphere.

Volume of a sphere 4/3 JI R3 Volume of half sphere 2/3 JI R3 Volume of cylinder JI R2 h Let h-yR Total tank volume = 2/3 JI R3 + JI R3 y JI R3 (2/3) + y) Since volume required is 211000 cu cm RI 211000/JI (2/3 + y) Selecting y = 7 R3 = 211000/JI (2/3 + 7) 211000/3.142 x 7.667 8759 R = 20.613 cm D = 41.25 cm Total height 8R = 164.9 cm 1.65m Air vessel size calculation Total required volume 76 Itrs 76000 cu cm Two tanks therefore volume per tank = 35000 cu cm As above total tank vol= ji R3 (2/3 + y) Let y = 20 then 3500 3. 142 R3 20.6667 R3= 35000/3. 142 x 20.6667 539 R = 8.1 cm D = 16.2 cm Total height 21R = 170 cm 1.7 m

The dimensions and capacity of the cylinder 10 and expansion tanks 114 will, of course, depend upon specific design requirements, and the present invention is not intended to be limited in any way in this regard.

Thus, as described above, all internal appendages are fixed to and centred on the insulated outlet tube 20 passing through the centre of the base plate 16, i. e. all "services"enter or leave the cylinder 10 via the base plate 16. The base plate 16, together with its appendages are connected together (and may be brought to the front of the base plate 16 for ease of connection) such that removal of the base plate 16 enables simple removal from the cylinder 10 of all of the appendages together for service, inspection and repair. Further, the container may be provided with a base stand (not shown) to provide sufficient space between the bottom of the base plate 16 and the surface on which the base stand is located and to enable easy access to the base plate 16 to remove it and all of the appendages, as described above.

A specific embodiment of the present invention has been described above by way of example only and it will be apparent to a person skilled in the art that modifications and variations can be made to the described embodiment without departing from the scope of the invention.

Claims

CLAIMS :

1. A liquid heating and storage system comprising means for heating cold water, container means for storing the heated water and outlet means which extends from a position close to the top of the container means through an opening at or adjacent to the bottom of the container means.

2. A system according to claim 1, wherein the container is a cylinder, preferably of reinforced plastics material, aluminium, enamel steel, copper or the like.

3. A system according to claim 1 or 2, wherein inlet means are provided to introduce cold water into the container, in which case, heating means to heat the cold water are also provided within the container.

4. A system according to claim 3, wherein the heating means is an electric heater, a directly-driven combustion heater, an indirect coil from another heating source, e. g. hydraulic coil, or any other suitable heating means.

5. An electric heater for heating liquid, the heater comprising a conductive element housed within a heat conductive member containing a heat conductive fluid.

6. A heater according to claim 5, wherein the heat conductive fluid is oil.

7. A heater according to claim 5 or claim 6, wherein the heat conductive member is coil-shaped.

8. A heater according to claims 5,6 or 7, wherein the heat conductive member is metal.

9. A liquid heating and storage system, comprising container means, means for introducing cold liquid into said container means, and means for heating the cold liquid, the means for introducing the cold liquid into the container comprising flow regulating means having an inlet of a first diameter for introducing cold liquid into the flow regulating means, and a plurality of outlets each having a diameter less than said first diameter but having a collective diameter greater than said first diameter.

10. A system according to claim 9, wherein the inlet to the flow regulating means comprises a pipe or tube which extends upwardly into the container means from an opening in the bottom of the container.

11. A system according to claims 1 to 4, or 9 or 10, comprising excessive temperature relief means and/or excessive pressure relief means.

12. A system according to claim 11, wherein the temperature and/or pressure relief means comprise one or more valves attached to a respective tube which extends upwardly into the container means from an opening in the bottom of the container means.

13. A liquid heating and storage system, comprising a generally cylindrical container which is closed at one end, the other end being covered by a removable base plate, the system further comprising inlet means for introducing cold liquid into said container, means for heating said liquid and outlet means for drawing heated liquid from the container, the inlet means, outlet means and heater supply means extending into the container through a respective opening in the base plate and being connected thereto, such that when said base plate is removed from the container, the inlet means, outlet means and heating means are also removed therefrom.

14. A system according to claim 13, wherein the base plate is on the bottom of the container.

15. A system according to claim 13 or claim 14, wherein the container is provided with a base stand to support it above the ground.

16. A liquid heating and storage system, comprising means for heating liquid, means for storing the heated liquid, and elongate temperature sensing means contained within and extending along a substantial portion of the length of the storage means for detecting the temperature of liquid in the storage means at a plurality of different portions.

17. A system according to claim 16, wherein the temperature sensing means includes or is connected to means for providing temperature readings in a format which allows the temperature profile of the storage means to be assessed.

18. A system according to claim 16 or claim 17, comprising means for determining the quantity of heated liquid in the storage means and for providing such information to local and/or remote decision making means.

19. A liquid heating and storage system, comprising container means, inlet means for introducing cold liquid into the container means, means for heating the cold liquid within the container means, and outlet means for drawing at least some of the heated liquid out of the container means, the system further comprising an expansion chamber consisting of a container airlock which is exposed to the contents of the container means, the air within the airlock being compressed in response to rising pressure within the container means.

20. A liquid heating and storage system comprising means for heating cold water, container means for storing the heated water and means for relieving the temperature within the container means if it exceeds a predetermined level comprising temperature limiting/relief valve means which is exposed to and immersed in the heated water, preferably at or adjacent the top of the container means.

21. A liquid heating and storage system substantially as herein described with reference to the accompanying drawings.

22. An electric heater substantially as herein described with reference to the accompanying drawings.