WO2003002915A1

WO2003002915A1 - Arrangement in a heating or cooling system

Info

Publication number: WO2003002915A1
Application number: PCT/SE2002/001288
Authority: WO
Original assignee: Andersson, Ola
Priority date: 2001-06-27
Filing date: 2002-06-27
Publication date: 2003-01-09
Also published as: SE0102268L; SE0102268D0

Abstract

The invention refers to a heating- and cooling system (1) comprising a closed tank (2) working as an accumulator tank containing a volume of liquid (5), preferably water, and a colume of gas (3), preferably nitrogen, said tank (2) being designated to give off energy for heating or cooling of preferably a building or stored water or some other liquid while preventing entrance of air. An expansion bellows (7), which is provided to communicate with said gas volume (3) in the tank (2), is directly or indirectly connected via at least one connection (8) to the upper part (4) of the tank (2) in order to take up changes in the volume- and/or pressure of the liquid volume (5) and/or gas volume (3) on the tank (2) in order to take up changes in the volume- and/or pressure of the liquid volume (5) and/or gas volume (3) in the tank (2) at the same time as said expansion bellows (7) prevents entrance of air and oxygenation of the water in the tank, a constant low pressure being maintainable in the system (1) regardless of how the above-mentioned volumes and pressures of water and gas varies.

Description

Arrangement in a heating or cooling system

The present invention refers to a heating- or cooling system, preferably for buildings, having a mainly pressure-free tank, which preferably serves as an accumulator tank, containing a volume of liquid, preferably heated water, and a volume of gas, preferably nitrogen, where the tank is directly or indirectly connected to an expansion bellows, which is capable of taking up changes in volume, at which a small pressure exists in the volume of gas in the tank included in the system.

Existing designs of the type in question on the market utilize different solutions to store and pump heated water in different parts of a heating system e.g. a tank, radiators, piping, expansion vessels, pumps, valves, taps etc. used in heating a building or similar. To prevent the different parts in the heating system from being decomposed by oxidation by incoming air, which oxygenizes the water via e.g. air intakes in expansion vessels or by leakage somewhere, caused by e.g. evacuation of the radiators, today thick and high-quality sheet-metal resistant to this oxidation for a large amount of time is used, at which these structures turn out to become expensive to purchase, maintain and handle. If thin, cheap sheet-metal is used, the lifetime is considerably reduced. Another way of extending the lifetime of the system is to prevent oxidizing of the water by enclosing it, so that no oxygen is able to force it's way into the water, at which the system is periodically exposed to large amounts of pressure, which results in thick and high quality materials, which are resistant to this pressure, must be used in the system, which implies expensive and technically advanced designs in the form of special safety valves, pressure vessels, expansion vessels etc. must be used. This type of heating system furthermore becomes susceptible to leakage, other damages and to the risk of explosion. In many cases the tank- is being used as an accumulator tank and must be carried out in strong metal-sheet and in a special design with belonging expansion vessel. Ordinary heating systems normally does not contain air. Other heating systems work with tanks under low pressure, which is being clear from e.g. the US patent 4,135,443 and the PCT-publication WO 93/18989, to be able to create a closed system unable to let air in. -According to tank norms, there must be an open connection to the surroundings, in order to be approved for the usage as accumulator tank, which is often missing. These low-pressure systems are equipped with expansion bellows, which are designed in a non-rigid material and applied inside the tanks, at which an increased volume of water and air is able to be consumed by said expansion bellows at the same time as a higher pressure in these is built up, so that hey are compressed and decreases in volume. The problem with this solution is yet that the compressed expansion bellows build up a back pressure, which increases the more they are^' compressed, which makes the pressure still increases in the air volume and the heating system as a whole. If the pressure in the heating system exceeds 0,03 bar, yet thicker and more expensive materials and complicated designs must be used according to the regulations, which are applicable to low- pressure, tank norm, and high-pressure, pressure vessel norm, in heating systems and tanks . Furthermore these designs are- difficult to maintain, since the expansion vessels are contained in the tank. Problems also come up, as the tanks can not be completely filled with warm- water, because the pressure then become too large, why the energy- losses becomes unnecessary large, as you are not able to make use of the whole tank and because of the outer exposed surface become large. Furthermore these internal expansion bellows could cover pre-made holes for e.g. safety valves or they can break without notice, at which the function is put at risk and rust damages emerge. Most heating systems are equipped with expansion vessels in contact with outside air, at which these easily rust no matter which type of heating system being used. In heating systems nowadays a leakage in the system maintain unnoticed, which results in water damages .

An object with the present invention is to eliminate the disadvantages in question in the abovementioned designs by providing the system with an expansion bellows, so that changes in the volume in the tank can be consumed by said expansion bellows without the pressure in the tank included in the system increases or just increases marginally.

Thanks to the invention one has now accomplished an arrangement in a heating- or cooling system containing a volume accumulating expansion bellows, applied outside a tank, which is able to take up the changes in volume and pressure, which occurs in the system and the tank connected to the same. The expansion bellows is connected by a first connection directly to the tank or by a second connection indirectly to the tank, which then is connected somewhere to the system itself. The expansion bellows is then capable of accumulating the changes in pressure and volume which occurs when the liquid and/or gas volume changes in the tank. The volume of gas consists of mainly nitrogen' and the volume of liquid consists of water. The volume of liquid and gas along with the pressure of liquid and gas changes in the ^' tank when temperature and atmospheric pressure variations emerge and when variations of the amount of liquid in the tank occurs. When the pressure in the tank increases, the pressure levels out, at which the pressure variations is accumulated by the expansion bellows. Since the bellows is volume accumulating, it can accumulate ^'the increase of pressure and/or volume at the same time as it expands and accumulate the decrease in pressure and/or volume as it contracts, at which a constant low pressure is created in the tank and in the system. This pressure is then at a level, which often is close to 0 bar or at least below 0.03 bar 'no matter how the volume of water and air and the pressure of water and gas varies, at which cheap materials and simple designs can be used, since they, according to the invention, are not exposed the severe stresses of high pressures. By a preferred embodiment example of the invention the tank is equipped with a volume accumulating expansion bellow, placed near the tank through the first connection at the upper part of the tank. The expansion bellows can be designed preferably of butyl rubber. Though, different materials such as rubber, plastic, -wood, metal or combinations of these can be used showing different shapes such as e.g. spherical, oval, concertina formed, cylindrical, bellow formed or as a gas dome or show other shapes. The tank may also be complemented with a second connection, which is connected to a . valve and a safety valve, which opens and closes at the discharge and filling up of gas. Thanks to the placement of the expansion bellows outside the tank, the back pressure in it doesn't increase very much, when the tank is mainly filled with liquid and/or gas when the temperature of the liquid is high, at which the pressure in the tank is constantly low. Furthermore, to reduce the risk of the oxygen being exposed to the volume of nitrogen in the tank and to reduce the risk of condensation and water being transported into the expansion bellows, a water seal may be applied to the upper connection. A safety connection may also be connected to the volume of liquid in the tank at a level not exceeding 0.3 m from the upper part of the tank. This safety connection creates a water seal with a back pressure. This back pressure can in some cases be at maximum 0.03 bar, at which a possible excess pressure may pass out through this connection with no chance of the outer air to force its way in. This safety connection may also be used as a level control. The expansion bellows may, according to the invention, be placed anywhere inside a building, which means available spaces may be utilized at a maximum and the expansionsbalg being easily accessible for maintenance. Furthermore, the tank may be designed in an arbitrary shape, when it does not have to be designed in such a firm way with a statically demanding design, since the system is working under low pressure, at which the tank is not exposed to any greater stresses. Therefore, you can use small spaces, such as a open foundation under buildings for the placement of the tank. If an excess pressure in the tank is preferred, the expansion bellows may be exposed to a weight or some other force, at which the excess pressure in the tank becomes the same no matter how large the volume of liquid and/or gas in it is. You may also use old second-hand oil storage tanks as tank for the system according to the. invention, which saves a lot of money and usage of available resources. The invention may also be used for district heating plants with- large tanks, apartment blocks and also small weekend cottages. The invention may as well be applied through simple cheap solutions without circulation pumps, at which the system becomes gravity circulating. Furthermore, the system can be used for production of new buildings and also for already existing tanks e.g. in arrangements with open expansion vessels, which then are replaced or complemented with the expansion bellows according to the invention. Thus, the main advantages with the invention are that you have an accumulator tank for a system which is cheap, easy to handle and install and which can be suitable for small and large buildings and heating plants and which is flexible, since it may be placed in cramped spaces. Furthermore, the system according to the invention, itself checks whether a leak has come up in the system. If that is the case the expansion bellows collapses by contracting itself completely. The expansion bellows can be manufactured and held in stock in different standard sizes, therefore it does not have to be tailor-made for each system, making it possible to manufacture at a reasonable cost. The invention is described more detailed by aid of preferred embodiment examples under reference to the drawings enclosed, in which

fig. 1 shows a schematic perspective view of a tank partly in section having an expansion bellows according to the invention,

fig. 2 shows a schematic perspective view of an upper part of a tank partly in section having a water seal,

fig. 3 shows a schematic perspective view of an upper part of a tank partly in section having a cooling coil,

fig. 4 shows a schematic perspective view of an alternative design of the invention partly in section,

fig. 5 shows in subfigures a-e outline perspective views of different shapes of an expansion bellows ,

fig. 6 shows in subfigures f-i outline side-views of different shapes of an expansion bellows containing a small and large amount of gas respectively,

fig. 7 ,8 show alternative solutions of safety valves on the tank in the form of water seals ,

fig. 9 shows a safety device at the expansion bellows, which is triggered off at too large pressure, fig. 10 shows an alternative design of the connection to the expansion bellows,

fig. 11 shows an alternative design of the system according- to the invention with belonging solar collector and

fig. 12 shows an alternative connection of a solar collector to the system according to the invention.

As the design of the invention presented in fig. 1 shows, it consists of a heating- or cooling system 1 consisting of a tank 2, which in the presented example serves as an accumulator tank containing a volume of gas 3 'in its upper part 4 and a volume of liquid 5 in its lower part 6. The volume of liquid 5 varies in volume depending on how much liquid, preferably water, which at the moment is in the system 1 and how hot the water is. The upper part 4 of the tank 2 is connected to an expansion bellows 7 via a first connection 8, at which the volume of gas 3, preferably nitrogen, can respectively increase and decrease in volume in said expansion bellows 7. A second connection 14 is connected to the first connection 8 and equipped with a valve 15 for filling up water and/or gas and a safety valve 16, which opens if the pressure becomes too high. A safety connection 17 connects to the tank 2 at a distance of maximum 0.3 m below the upper part 12 of the tank. This constitutes a level control and also prevents excess pressure from appearing in the tank 2. The upper part of the safety connection 17 is at the same level as the upper part 12 of the tank 2. The volume of liquid 5 emits energy to the system 1 by allowing the water to circulate the system 1 to the radiators. You could also connect a pipe 20 in the tank 2 to the radiators, at which no mixing of the volume of liquid 5 and the water in the radiators will occur, at which the energy in form of heated or cooled water is given off to radiators etc. through an outlet 18, so that the water is cooled or heated when the energy is emitted by the radiators and then the water returns through an inlet 19 to the pipe 20. Of course, the volume of liquid 5 may pass directly out through the outlet 18 and return through the inlet 19 without utilizing the pipe 20, at which the volume of water 5 circulates the radiators.

As clear from fig. 2, here the upper part 4 of the tank 2 and the first connection 8 to the expansion bellows 7 is shown, whose first connection 8 is formed as a water seal 10.

Here is, as is illustrated in fig. 3, the upper part 4 of the tank 2 and the first connection 8 to the expansion bellows 7, shown, whose first connection 8 is designed as a cooling coil 21, which cools the volume of gas 3 on its way to the expansion bellows 7, at which the volume of gas slightly decreases.

As clear from fig.4, here is an alternative design of the invention shown, at which the tank 2 proves to have the first connection 8 bent at a point 22 and a point 23, where point 23 is located higher than point 22, so that the first connection 8 between points 22 and 23 is leaning, at which any possible condensation water in it ' may flow back into the tank 2 in a direction 24. The expansion bellows 7 may then be connected at a lower point than where the • volume of gas 3 is located without being filled with condensation water. This gives great freedom of placing the expansion bellows 7 anywhere in e.g. a building in e.g. a boiler room.

If condensation water still remains in the first connection 8, it may be collected in a point 25 where the first connection proves to have a bend upwards towards the expansion bellows 7, at which the condensation water flows down to point 25, where it later may evaporate. Since the first connection 8 may be designed in a way that it on at least one point is in contact with or close to the tank 2, heating occurs, which makes the evaporation of the condensation water easier.

As clear from fig. 5, here is an example of different shapes, which the expansion bellows 7 may show. In subfigure a/ it's oval-shaped, in subfigure b/ it's spherical, in subfigure c/ it's concertina formed, in subfigure d/ it's bellow formed and in subfigure e/ it's cylindrical in a rigid cylinder 26 with a moveable piston _.27 in it, which can move so that changes in volume can be taken up. Each subfigure also proves to have the first connection 8. Naturally, you may according to the invention combine these different shapes in one single expansion bellows 7. Of course, other shapes than these may also exist for the application of the invention, e.g. in the shape of a gas dome. As clear from fig. 6, here subfigure f/ shows how an oval-shaped or a spherical expansion bellows 7 can look like when its volume of gas 3 is small. Subfigure g/ shows a concertina formed bellows in the same situation. In subfigure h/ a bellow formed bellows and in i/ a cylindrical bellows in the same situation .

In the design shown in fig. 7 and 8, the tank 2 has instead of mechanical valves been equipped with a water seal 28, which is connected to the upper, gas-filled part of the tank 2 and prevents excess pressure from appear in the tank 2. The height of the water seal 28 determines the maximum excess pressure or under-pressure . Here the liquid-filled part of the water seal may be connected to the tank 2 with a small pipe 29 for automatic fill up, so that it won't dry out.

Fig. 9 shows a stretched band 30 around the balg 7 which is fixed at one end and connected to a trigger device 32 with its second, open end 31, at which when exceeding a pre-defined pressure in the bellows 7 opens a valve 33 when the device 32 is pulled out. Alternatively the bellows 7 may have a weakening, which breaks at a pre-defined, small excess pressure.

In fig. 10 the expansion bellows 7 shows at its connection 8 a perforated spacer 34, which lets the gas through when the bellows 7 is almost empty. Due to this the gas may pass out through the side-walls of the spacer 34 and then the side-walls of the rubber sheet cannot cover the opening to the connection 8. Fig. 11 and 12 shows a, through connection 43, 44, directly connected to the tank 2, solar collector 35, which at its operation is filled with oxygen- free water from the tank, having a distance of change in volume 45 and is brought circulating by the pump 41 through the pipes 38 and 39. In the example shown in fig. 12 there is also a nitrogen draining-pipe 37 present, with which the solar collector 35 may be drained thanks to the gas from the bellows 7 with surrounding air unable to force its way into the solar collector system and cause damages by oxidation. Further on, there's a water seal 46 for the nitrogen. Due to this solution, cheap pressure-free accumulator tanks may be used at the same time as a solar collector, which cannot withstand high pressures, become usable. At rest, the solar collector 35 is empty of water, since the pipes 38,39 has its water in the same level as the water surface in the tank. At this moment, the solar collector 35 is filled with gas and when the sun emits energy, the pump 41 starts the circulation to the solar collector from the tank 2 via a control equipment, not shown in the drawings, and the solar collector is now in operation. When the tank 2 is warm enough, the control equipment shuts off the pump 41 and the solar collector 35 is emptied of water and the nitrogen flows up to it from the expansion bellows 7 and the solar collector again is at rest.

In fig. 12 there is an alternative connection 42 for draining with or without valves or a valve- control may be fitted at a suitable point on the pipes 38,39 from the solar collector 35.

Claims

1. A heating- or cooling system (1) comprising a tank (2) having a liquid volume (5), preferably water and a gas volume (3)., preferably nitrogen, said tank (2) is intended to give off energy for heating or cooling of preferably a building or stored water or some other liquid while preventing entrance of air, characterized in that the tank primarily serves as an accumulator tank an is provided with an expansion bellows (7) communicating to its gas volume (3), said expansion bellows (7) is directly or indirectly connected to the upper part (4) of the tank (2) via at least one connection (8) in order to take up changes in the volume- and/or pressure of the liquid volume (5) and/or gas volume (3) in the tank (2) at the same time as said expansion bellows (7) prevents entrance of air and oxy- genation of the water in the tank, a constant low pressure being maintainable in the system (1) regardless of how the above-mentioned volumes and pressures of water and gas varies.

2. A system according to claim 1, characterized in that the expansion bellows (7) is made of preferably butyl rubber and is, when filled, either oval-shaped, spherical, concertina formed, bellow formed or cylindrical.

3. A system according to claim 1, characterized in that the tank (2) in its upper part (4) or at the first connection (8) is provided with a second connection (14) for filling of liquid and/or gas, said second connection (14) contains a valve (15) and/or at least a safety valve (16) and/or a water seal (10,28,46).

4. A system according to claim 1, characterized in that the first connection (8) is in the form of a water seal (10) .

5. A system according to claim 1, characterized in that the tank (2) is provided with a level and overpressure control in the form of a safety connection (17), which is connected to the liquid volume (5) in the tank (2) at a predetermined distance from the upper part (12) of the tank (2), said safety connection (17) can withstand a back pressure.

6. A system according to claim 1, characterized in that the first connection (8) is designed as a cooling coil (21) .

7. A system according to claim 1, characterized in that one part of the first connection (8) is bent in its upper part in a first point (22) and thereafter bent in a second point (23), said second point (23) being located higher than the first point (22), whereby the connection (8) between the points (22,23) are leaning in a direction (24) towards the tank (2), any condensation water being able to flow back into the tank (2) .

8.- A system according to any of the preceding claims, characterized in that at least some part of the first connection (8) is provided with at least one point (25), which is heatable by some source of heat in order to increase evaporation and which is located lower than the expansion bellows (7), condensation water can be gathered at this point (25) to evaporate.

9. A system according to any of the preceding claims, characterized . in that the gas-filled upper part of the tank (2) is provided with a water seal (28) to prevent an excess pressure in the tank (2) and said water seal (28) in its lower part being connected to the content of the tank via a pipe (29) for automatic filling of water into the water seal (28) .

10. A system according to claim 1, characterized in that the expansion bellows (7) is provided with a weakening, which breaks at a predefined low pressure or is provided with a stretching band (30), which at the predefined pressure is stretched out and with a free end (31) releases a trigger device (32) from a valve (33) connected to it.

11. A system according to claim 1, characterized in that the connection (8) of the expansion bellows (7) is provided with a perforated spacer

(34) in order to let gas flow through it when the bellows (7) is almost empty.

12. A system according to claim 1, characterized in that a draining solar collector (35) is directly connectable to the system (1), said solar

- collector (35) being filled with oxygen-free water when operating, and filled with nitrogen at^' rest .

13. A system according to claim 12, characterized in that the upper part (36) of the solar collector (35) is provided with a nitrogen- draining-pipe (37;42) connected to the connection (8) of the expansion bellows (7) .

14. A system according to claim 12, characterized in that the solar collector (35) is directly connected to the envelope surface (40) of the tank (2) via pipes (38,39) .