WO2016020893A1

WO2016020893A1 - A thermal storage tank

Info

Publication number: WO2016020893A1
Application number: PCT/IB2015/056020
Authority: WO
Inventors: David Kenrick DEANE; Jason Kenrick DEANE
Original assignee: Deane David Kenrick
Priority date: 2014-08-08
Filing date: 2015-08-07
Publication date: 2016-02-11
Also published as: AP2017009714A0

Abstract

The invention related to a not water storage tank (1) which is erected from modular sidewall panels (3) that are made by injecting polyurethane as insulation between two metal sheets which include at least one elongate reinforcing member that is embedded in the polyurethane and extends from a top to a bottom edge. The sheets are bent to form tongue (6) and groove (7) engaging formations for connecting side edges of the panels (3). The sheets are spaced apart at the tongue (6) and groove (7) formations to prevent transmission of heat. The bottom edges of the panels are located in a rectangular base constructed from upwardly facing channels. The upright corners are reinforced by angle sections which are connected across the sidewalls by straps. A preformed EPDM liner is fitted into the tank and downwardly facing channels fitted over the liner onto top edges of the sidewalls. Two opposite top channels are connected by manifolds (14) for coiled heat exchangers and reinforcing connectors extend between the other two top channels. Each heat exchanger is made of corrugated steel tube wound around a harness suspended from a manifold. An external heat source maintains the temperature of the water in the tank and this is used to heat water that is pumped through the manifolds (14).

Description

A THERMAL STORAGE TANK

FIELD OF THE INVENTION The invention relates to a hot water storage tank of the kind that is insulated and used for storing large volumes of water that are heated by an external source. These tanks are used to transfer heat through immersed heat exchangers for supply of heated municipal water. BACKGROUND TO THE INVENTION

The conventional tanks used for storing heated water on a large scale are usually difficult to install in building structures where the hot water is needed. This invariably requires hoists, cranes, rigs etc. The installation adds to the cost and there are limitations placed on available options for a water heating system.

In addition, there are also difficulties in providing a tank construction which is suitably strong to retain the internal load from a large volume of water. OBJECT OF THE INVENTION

It is an object of the present invention to provide a tank that effectively performs the function of heating water for large volume applications and which avoids the usual installation difficulties and/or is cost effective to manufacture and/or provided with a suitably strong construction.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a large volume hot water tank having sidewalls constructed from panels each comprising a pair of metal sheets, with an insulating layer of polyurethane foam injected between the sheets and at least one elongate reinforcing member extending within the panel from a position at or adjacent an operatively bottom edge to a position at or adjacent an operatively top edge.

The invention further provides for a tank as defined: in which the at least one reinforcing member of the panel is secured to an outer sheet; in which the reinforcing for member is a channel with a web secured to an operatively outer sheet; and in which the channel is a lipped channel.

Further features of the invention provide for a tank as defined: in which two or more reinforcing members are secured spaced apart across a width of the panel; in which a panel includes cooperating tongue and groove formations at or adjacent opposite operatively upright edges; and in which each end of a tongue formation and each bottom of a groove formation is formed by the polyurethane foam which bridges a gap between the metal sheets of the panel. A further feature of the invention provides for the wall panel sheets to be inwardly stepped on both sides of the wall panel to provide a tongue formation, with free edges of the two sheets spaced apart at an end of the tongue formation.

A further feature of the invention provides for the two sheets to be bent inwardly at the end of a first type of wall panel to form two spaced apart returns that form the sides of the groove formation. In the case of a second type of wall panel, a further feature of the invention provides for the sheet on the outside of the wall panel to bent around a side edge of the panel to a position where it corresponds to the inner sheet and, at the position where the groove is required, for the two sheets to be bent to form inwardly disposed lips that provide the sides of the groove.

Further features of the invention provide for a tank as defined: in which bottom edges of the panels are located in upwardly facing channels that are secured together to form a base; in which oppositely disposed base channels are secured together by connecting strips which extend beneath the tank; in which downwardly facing top channels are located over upper edges of the panels; in which the top channels are located over the liner.

Further features of the invention provide for a tank as defined: in which straps are secured across each sidewall and connected at upright corners of the tank; in which the straps are secured between angle sections located along upright corners of the tank; in which at least one pair of oppositely disposed top channels are connected by elongate manifolds for heat exchangers; in which elongate reinforcing connectors extend across the manifolds between oppositely disposed top channels.

Further features of the invention provide for a tank as defined: which includes an external heat source for water in the tank and a heat exchanger header set comprising first and second elongate manifolds secured as connecting beams between sidewalls across a top of the tank, one manifold having an inlet and the other an outlet with a series of heat exchangers suspended from and connected across the two manifolds; and in which the heat exchangers are coils of stainless steel corrugated tubing.

Further features of invention provide for the inlet to be at one end of the first manifold and the outlet at the oppositely disposed end of the second manifold; and for each manifold to include a plurality of downwardly disposed spigots for connection to heat exchangers; for spiral (or coiled) stainless steel tubing heat exchangers to be suspended from the header set into the tank. A further feature of the invention provides for the heat exchangers to be connected across the inlet and outlet manifolds in a balance or reverse return piping arrangement. A further feature of the invention provides for a tank as defined: in which each heat exchanger coil is mounted on a harness with a suspension loop which is slidably located onto the manifold.

Further features of the invention provide for the harness to include a pair of spaced apart parallel supports around which the tubing is wound; and for elongate heat exchanger coil support clips (preferably, made from Nylon) having spaced apart tube engaging grooves to be connected to the harness to maintain the coils in spaced apart relationship from each other. Further features of the invention provide for a tank as defined: in which the liner preformed from EPDM rubber; and which includes an insulated base provided as an insert and an insulated roof provided as a plurality of lid sections.

A further aspect of the invention provides for a kit including components for erection of a tank as defined.

The invention will also extend to any new and inventive methods associated with the tank and panel construction. BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent from the following description of one embodiment, made by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view of a partly erected hot water tank; Figure 2 shows a perspective view of a tank (without a roof and liner); Figure 3 shows a plan view of the tank in Figure 2;

Figure 4 shows a perspective view of a coil for a heat exchanger; Figure 5 show various views (side, plan, end and perspective) of a header manifold;

Figure 6 shows an exploded perspective view of the tank;

Figure 7 shows a perspective view of a tank with a roof in place; and

Figure 8 shows a perspective view of connecting formations for a join between contiguous ends of a pair of panels;

Figure 9 shows a perspective view of connecting formations for a corner join between a pair of panels;

Figure 10 shows various views (side, plan and end) of a first type of wall panel providing aligned connecting formations at both ends;

Figure 1 1 shows various views (side, plan and end) of a second type of wall panel providing an aligned connecting formation at one end and a corner connecting formation at the other end;

Figure 12 shows a smaller wall panel with the same connecting formation configuration as the panel in Figure 10; and

Figure 13 shows schematic plan views of various tank configurations.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, an insulated hot water tank (1 ) is shown together with various views illustrating its construction.

The tank (1 ) is provided from modular components for flat packing on one or two pallets and to be erected on site. This allows the use of lifts and stairs and avoids the necessity of hoists or cranes to get the tank onto the roof of a building or into a basement, for example.

The tank (1 ) has four sidewalls (2) constructed from panels (3) are made from polyurethane foam which is direct injected between epoxy coated galvanized Chromadek steel sheets (4.1 ) and (4.2) (which provides a cladded wall construction). The wall panels (3) are 60 mm thick.

The vertical join lines (5) between sidewall panels (3) making up the sidewalls (2) of the tank (1 ) are shown in the drawings. The top of one such connection between a planar arrangement of connected panels is shown in Figure 8 and the top of a corner connection is shown in Figure 9.

The panels (3) are formed with cooperating tongue (6) and groove (7) formations.

A first type of panel (2.1 ) has a longitudinal groove (7.1 ) formed along one (operably vertical) edge of the panel (2.1 ) with a tongue (6.1 ) formation along the other opposite edge. The first type of panel (2.1 ) is provided in two different widths: 1 170 mm as shown in Figure 10 and 580 mm as shown in Figure 12.

A second type of panel (2.2) is illustrated in Figure 1 1 . This has a tongue (6.2) formation along a first vertical edge but a groove (7.2) formation is formed on a side surface of the wall panel (2.2), closely spaced apart from the opposite, second vertical edge. The second type of wall panel (2.2) serves to receive a tongue (6.1 ) formation of a first type of wall panel (2.1 ), arranged at 90 degrees to provide a corner of the tank (1 ).

In accordance with the invention, the tongue (6) and groove (7) formations of both the first (2.1 ) and second (2.2) type of wall panel are formed by suitable bending of the Chromadek sheet (4.1 ) and (4.2).

To form a tongue (6), the Chromadek (4.1 ) and (4.2) is inwardly stepped at (8) on both sides of the wall panel (3). Free edges of the two Chromadek sheets (4.1 ) and (4.2) are spaced apart at the end of the tongue (6). When the wall panel (3) is formed, the injected polyurethane foam spreads to fill the space between the two opposite inwardly stepped portions (8). This provides an insulating region (6.3) across the end of the tongue (6) that prevents any bridging between the conductive material of the two side sheets (4.1 ) and (4.2). To form a groove (7.1 ), the Chromadek sheets (4.1 ) and (4.2) are bent inwardly at (9) the end of a first type of wall panel (2.1 ) and then to form two spaced apart returns (10) that provide the sides of the groove (7.1 ). In the case of a second type of wall panel (2.2), the Chromadek sheet (4.2) on the outside of the wall panel (2.2) is bent around a side edge of the panel at (1 1 ) to a position where it corresponds to the inner sheet (4.1 ) of Chromadek. At the position where the groove (7.2) is required, the two sheets (4.1 ) and (4.2) of Chromadek are bent to form inwardly disposed lips (12) that provide the sides of the groove (7.2).

The bottom (7.3) of each groove (whether for an end-to-end or corner connection) is formed by the polyurethane foam of the wall panel (3). This arrangement again avoids any bridging between the two inner (4.1 ) and outer (4.2) Chromadek sheets that form the wall panel (3).

The polyurethane (6.3) across a free end of a tongue (6) abuts or is located close to the polyurethane forming a bottom (7.3) of the groove (7) to provide an insulation barrier where the wall panels (3) are joined.

The bent configuration of the Chromadek (4.1 ) and (4.2) as described provides the tongue (6) and groove (7) formations with a regular linear profile of predetermined size for the required mating fit and serves to provide these overlapping components/formations with a suitable tolerance. The tongue (6) and groove (7) formations so formed have rigid sides that slide into abutting engagement bringing the insulated polyurethane at (6.3) and (7.3) substantially into contact (or into close proximity). [The insulation bridge at the joint configuration may be facilitated by allowing the polyurethane at each tongue (6) and/or groove (7) to bulge (outwardly) by a small or suitable degree. The "protruding" or "bulging" portions of the foam are then pressed against foam on the opposite side of a join to provide an insulated boundary between the sheets (4.1 ) and (4.2) that extends along a join line (5).]

In this manner, the inner sheets (4.1 ) of the wall panels (3) of a tank (1 ) do not contact the sheets (4.2) on the outside of the tank (1 ) and thermal bridging that would otherwise result is avoided. The heat in the tank water is thus more effectively retained. There are accordingly three different types of panels (3):

• those for corners (Figure 1 1 );

• those of standard size for straight connection (Figure 10); and

· the short panels for straight connection (Figure 12).

Figure 13 shows plan views of different tank formations that are constructed from these panels (3). The wall panels (3) shown in Figures 10 to 12 are 1700 mm high. Equivalent panels (3) of the same width but 1900 mm high will be used to construct tanks with the same footprint and an increased volume. This will also affect the number of lid sections (13) used and the number of header set manifolds (14), or at least the number of outlets and inlets (15) to and from the heat exchange coils (16) provided along the manifolds (14). Each manifold (14) can have from 2 up to 8 distribution points [outlets from the incoming manifold (14A) and inlets to the outgoing manifold (14B). The number of heat exchangers (16) will accordingly be increased depending on the size of tank (1 ) and volume of water to be heated.

Depending on the number and height of the wall panels (3) used, a tank 91 ) may be provided with a capacity of between 1600 litres to 1 1000 litres.

The two Chromadek sheets (4.1 ) and (4.2) for a given wall panel (3) will be cut to the required dimension to provide a blank and then bent to form the required steps (8), returns (10) and/or lips (12) for the tongues (6) and groove (7) formations

Elongate reinforcing members (17) are then secured to the outer sheet (4.2) of each panel (3). The reinforcing members (17) provide a structural cage around the sides of the tank (1 ). These members (17) are provided, in this embodiment, as operatively upright beams of suitable strength that are formed by lipped channels. The steel reinforcing channels (17) are shown by broken lines in the side views of Figures 10 to 12. The channels (17) are riveted to the outer sheet (4.2). This serves to keep the channels (17) in the required position during the foam injection process.

The internal reinforcing members (17) are protected by the polyurethane. This allows the use of mild untreated steel sheeting that is press into the required channel profile to provide rigidity to the panel.

The sheets (4.1 ) and (4.2) are placed one on top of the other between a pair of jigs. The polyurethane foam is injected into the cavity between the two outer skins (4.1 ) and (4.2). The jigs limit separation of the sheets (4.1 ) and (4.2) to provide the panels (3) at the required thickness. The jigs also maintain the two sheets (4.1 ) and (4.2) in the required alignment so that the tongue (6) and groove (7) formations are formed to the required size and with the required configuration between the steps (8), returns (10) and/or lips (12) at the edges of the sheets (4.1 ) and (4.2). The foam surrounds the lipped channel (17) and binds over the inner surfaces of the sheets (4.1 ) and (4.2) to complete the panel (3) and fix the spatial relationship between the sheets (4.1 ) and (4.2) that provides the tongue (6) and groove (7) formations. The jigs allow the inner sheet (4.1 ) to be moved to a position spaced apart from the channel flanges so that there is no metal contact through the reinforcing members (17) between the inner (4.1 ) and outer (4.2) sheets.

Each panel (3) has a minimum of two embedded steel lipped channels (17) fixed (operatively) vertically within the polyurethane foam between the Chromadek sheets (4.1 ) and (4.2).

This construction provides a robust sidewall panel (3) arrangement with an internal supporting structure having the necessary strength to support the weight of its water contents once the tank (1 ) is in use. The design of the panel (3) with its polyurethane layer and join construction at (5) provides favourable insulation properties to the tank (1 ). Referring to Figure 1 , a grid (18) of stainless steel support floor strips (19) are run horizontally on the bottom of the tank (1 ). Only four strips are shown but additional strips may be used for larger tanks. The floor strips (19) have upwardly disposed flanges (20) provided by bends at their outer ends which are secured to four upwardly facing lengths of channel (21 ) that provide a rectangular base (22) to receive bottom edges of the sidewall panels (3).

The flanges (20) at the ends of the strips (19) are secured to the base channels (21 ), which are also secured to the reinforcing channels (17) inside the sidewall panels (3) using bolts (alternatively, screws or rivets may be used).

The base channels (21 ) are secured together at the corners by underlying corner channel sections (21 .1 ) that provide a fixed 90 degree fitting for the ends of the channels (21 ).

The corners of the tank (1 ) are formed by abutting edges of the sidewall panels (3) (with the corner tongue and groove formations) supported within vertical angle sections (23), shown in Figures 1 , 6 and 7, that are screwed directly into the sidewalls (2).

Each sidewall (2) of the tank (1 ) is also fitted with an external, horizontal strap (24) located approximately midway from the base (22) to the top edges of the sidewalls (2). The horizontal straps (24) are also fastened to the sidewall panels (and extend across any joins (5) in the sidewalls (2), between the corners) with the ends of the horizontal straps (24) anchored under the corner angle sections (23).

Conveniently sized slabs of high-density polystyrene foam which are dimensioned to fit inside the base channels (22) are placed over the bottom support strips (19). These slabs provide the insulated floor (34) of the tank (1 ).

Four inverted top channels (25) are secured over the top edges of the tank sidewalls (2). These stainless steel top channels (25) serve to secure an EPDM rubber geo-membrane liner (not shown) that is used to line the inside of the tank (1 ). Once in position, the ends of the rubber are folded over the top edges of the sidewalls (2) of the assembled panels (3). This rubber is then held in place by the inverted channels (25), which are an oversized fit to the top edges of the sidewalls (2) to accommodate the liner. These channels (25) are fitted over the rubber liner on the top of the sidewalls (2) and also serve to reinforce and secure the sidewall panel (3) structure.

The top channels (25) are secured at the corners by overlying corner channel sections (25.1 ) that provide a fixed 90 degree fitting for the ends of the channels (25).

The EPDM rubber is moulded as an integral liner to the shape of the inside of the tank (1 ). This material provides the required waterproofing, can withstand high temperatures and is of adequate durability.

The feature of having a preformed liner eliminates creases and other problems associated with folding of a flat sheet liner. Significantly, the preformed liner takes very little time for proper installation. A roof (26) of the tank (1 ) is constructed with 40 mm rigid polyurethane panels clad with fibreglass, which provide lid sections that can be arranged side by side. The fibreglass is suited to deal with the heat and steam. Three such lid sections (13) fit onto the tank (shown in the drawings) to provide an enclosure environment.

The tank (1 ) includes two parallel stainless steel (grade 316 L) manifolds (14) forming a header set (27) provided as beams installed across the top of the tank (1 ), connected between two of top channels (25). The two outer lid sections (23) (which sit to either side of a central panel) are provided with openings that locate over an inlet (28) to a first, inlet manifold (14A) and an outlet (29) from a second, outlet manifold (14B).

The arrangement of the lid sections (13) facilitates easy removal without having to dismantle the header set (27) and connecting piping. Apart from an incoming line to the first manifold (14A) and an outgoing (heated water) line from the second manifold (14B), the flow lines are supported inside the tank from the manifolds (14) which themselves provide conduits for the required flow of water through the tank (1 ).

An internal shoulder (30) with a rubber gasket (not shown) is supported on the upper frame provided by the inverted channels (25). The lid sections (22) rest on the gasket and have a stepped edge profile providing peripheral flange that extends at least partly over the sidewalls (2) of the tank (1 ).

A separate pair of reinforcing connectors (31 ) extends across the header set (27) engaged between the opposite sidewalls (2) of the tank (1 ) that are parallel to the manifolds (14) of the header set (27). The header set (27) has three main functions:

• to distribute the pressurized potable water evenly between 316L spiral stainless steel heat exchanger coils (16) - as shown in Figure 4;

• to add load-bearing support to the framework and form part of the structure between the top edges of the tank to provide structural stability

(together with the connectors (31 ) referred to); and

• to act as supports to suspend spiral stainless steel heat exchanger coils (16). The spiral or coiled stainless steel heat exchangers (16) are suspended from the two manifolds (14) into the tank (1 ). The tube used for the coils (16) has a stepped or corrugated bendable wall with annular ridges and grooves that makes it suitable for this application. The corrugated profile of the tube wall generates vortexes which increase heat transfer efficiency and reduce the incidence of sludge and lime scale build up.

The heat exchangers (16) are connected across the inlet (14A) and outlet (14B) manifolds in a balance or reverse return piping arrangement that ensures equal (or substantially equal) water flow through all the heat exchangers (16). Water flows into the top ends of the coils (16) and downwards towards the bottom of tank (1 ), where it exits the coil and passes back up through a connection to the outlet header (14B) along which it flows into the exit tube or line connected at (29) together with water from adjacent coils (16).

Heat exchanger coil support clips (16.1 ) made from Nylon are provided with an undulating profile onto which the tubes of the heat exchanges (16) are wound. The stainless steel spiral tubing is rolled on a rolling machine and then clipped onto the support clip assemblies. The support clips (16.1 ) are connected to spaced apart support members of a harness (32) made from 304-grade stainless steel. This maintains the shape of the coils and separates the coils from each other. The nylon clips (16.1 ) are suitable up to a water temperature of 90 degrees Celsius.

The arrangement of the heat exchanger coils (16) serves to allow as much water as possible to flow around each loop of coil and maximise the surface area of the loop with the water to provide for a more effective heat transfer from the heated water in the tank (1 ) to the water inside the exchangers (16).

The harnesses (32) each have a suspension loop (33) which is located loosely onto each manifold (14) of the header set (27) and allows for manual sliding of the exchangers (16) along the length of each header. The flanges of the base channels (21 ) and top channels (25) overlap the ends of the reinforcing members (17) within the panels (3) to provide the tank with a braced and reinforced cage construction to support the insulated sidewalls against the internal load once the tank is filled. Heat pumps (not shown) circulate the water in the tank (1 ) to provide effective distribution of heated water around coils (16). The water pumped through and across the tank (1 ) from the supply and return water piping of the heat source to the tank acts as an agitator. This increases the efficiency of the heat exchangers. The flow of water is also directed between the heat exchanger coils to facilitate thermal transfer.

Unlike most hot water boilers/storage tanks, the modular tank is easily transportable and can be assembled on rooftops, in basements or in other remote or confined spaces or locations without the requirement of hoists, cranes, rigs etc. (The components can be easily transported in an elevator, for example). In addition to the convenient transport to an installation site the components of the insulated tank also enable easy and cost effective installation.

The invention accordingly provides tank of modular components that enable a suitably robust structure with the required insulation for hot water storage tank. The structure contains an EPDM rubber liner that provides a separate component for waterproofing. A fitted PVC tarpaulin cover will also be provided to keep dust and other dirt or material out of the water.

The components can easily be modified for assembly in different tank capacities. The tank will preferably be provided as a kit. The required components for a construction of a given capacity will be supplied together.

While the lipped channel profile for a reinforcing member (17) has be found to provide adequate strength and also allows the travel of the injected polyurethane to embed the component, it will be appreciated that alternative profiles or constructions of reinforcing members may also be used.

A person skilled in the art will appreciate that a number of changes may be made to the features described without departing from the scope of the current invention.

Claims

1 . A large volume hot water tank having sidewalls constructed from panels each comprising a pair of metal sheets, with an insulating layer of polyurethane foam injected between the sheets and at least one elongate reinforcing member extending within the panel from a position at or adjacent an operatively bottom edge to a position at or adjacent an operatively top edge.

2. A tank as claimed in claim 1 in which the at least one reinforcing member of the panel is secured to an outer sheet.

3. A tank as claimed in claim 2 in which the reinforcing for member is a channel with a web secured to an operatively outer sheet.

4. A tank as claimed in claim 3 in which the channel is a lipped channel.

5. A tank as claimed in claim 1 in which two or more reinforcing members are secured spaced apart across a width of the panel.

6. A tank as claimed in claim 1 in which a panel includes cooperating tongue and groove formations at or adjacent opposite operatively upright edges.

7. A tank as claimed in claim 6 in which each end of a tongue formation and each bottom of a groove formation is formed by the polyurethane foam which bridges a gap between the metal sheets of the panel.

8. A tank as claimed in claim 1 in which bottom edges of the panels are located in upwardly facing channels that are secured together to form a base.

9. A tank as claimed in claim 8 in which oppositely disposed base channels are secured together by connecting strips which extend beneath the tank.

10. A tank as claimed in claim 8 in which downwardly facing top channels are located over upper edges of the panels.

1 1 . A tank as claimed in claim 10 in which the top channels are located over the liner.

12. A tank as claimed in claim 10 in which straps are secured across each sidewall and connected at upright corners of the tank.

13. A tank as claimed in claim 12 in which the straps are secured between angle sections located along upright corners of the tank.

14. A tank as claimed in claim 10 in which at least one pair of oppositely disposed top channels are connected by elongate manifolds for heat exchangers.

15. A tank as claimed in claim 14 in which elongate reinforcing connectors extend across the manifolds between oppositely disposed top channels.

16. A tank as claimed in claim 1 which includes an external heat source for water in the tank and a heat exchanger header set comprising first and second elongate manifolds secured as connecting beams between sidewalls across a top of the tank, one manifold having an inlet and the other an outlet with a series of heat exchangers suspended from and connected across the two manifolds.

17. A tank as claimed in claim 16 in which the heat exchangers are coils of stainless steel corrugated tubing.

18. A tank as claimed in claim 17 in which each heat exchanger coil is mounted on a harness with a suspension loop which is slidably located onto the manifold.

19. A tank as claimed in claim 1 in which the liner preformed from EPDM rubber.

20. A tank as claimed in claim 1 which includes an insulated base provided as an insert and an insulated roof provided as a plurality of lid sections.