Device for thawing frozen ground

Abstract

 A device for thawing frozen ground or heating an area of ground, which device substantially comprises a container for storing a heating medium that is to circulate in a hose deployed for heating the ground, a boiler with a burner for heating the heating medium, which boiler is connected to the container for storing the heating medium, a fuel tank containing fuel for the burner in the boiler, which fuel tank is in connection with the burner in the boiler, a pump for circulating the heating medium, a hose placed on the ground that is to be heated, through which the heating medium circulates, which pump is mounted between the hose and the container for storing the heating medium and which pump circulates the heating medium in the hose. An aspect of the invention is characterised in that the container for the heating medium, the boiler with burner, the fuel tank and the pump are secured to a common framework construction, the hose consists of two or more hose segments and the hose segments are in an inactive state, coiled up on a substantially corresponding number of reel segments of a reel, where each hose segment can be selectively connected to the pump via a branch manifold mounted between the pump and each of the hose segments. In a further aspect of the invention, the invention is characterised in that the container for the heating medium, the boiler with burner, the fuel tank and the pump are secured on a common framework construction, which framework construction is provided with external brackets and/or supports for placing it on a transport unit.

Description

[0001] The present invention relates to a device for thawing frozen ground together with several aspects of this device.

[0002] There are many occasions when it is necessary to heat or thaw frozen ground. This may be necessary to enable the ground to be worked, for example, during digging or similar operations or to assist in a curing process, for example in concrete constructions in winter when the outdoor temperature is too low for the normal curing process. Some examples of areas of application are: thawing of ground frost when excavating earth, concrete work, thawing of ice, heating of buildings during construction, preventing ground frost from infiltrating a building during construction, thawing frozen pipes (water and sewage), heating large areas that are partly insulated or covered, or removing rime or frost on shuttering before pouring concrete. It may be particularly interesting to employ the solution as frost protection for preventing ground frost and frost from spreading into a building. This is particularly relevant during erection of a building, for example a storage building where the walls are erected first and the floor then poured internally. In such cases the device according to the invention can be employed to make the area round the building's outer edges frost-proof.

[0003] Traditionally various techniques have been used such as, for example, laying red-hot coals on the ground in order to thaw ground frost or loosen frozen ground. Alternatively, hot air solutions have been used where the air is heated by paraffin or electricity and blown under an insulating carpet, for example.

[0004] A further known solution is to insert a heating pod in the ground before heating it up in order to thaw the ground round it. This can be done, for example, by circulating a heated fluid medium in the pod, thus keeping it continuously at a suitable temperature.

[0005] Yet another solution is to pump a hot medium through a hose placed on top of the warm ground. This kind of solution can be very effective since a relatively large area can be heated up, a medium suitable for heating, with the right, appropriate properties, can be chosen and the solution can be easily insulated by means of ordinary insulating mats. The present invention utilises this principle and is a further development of previously known solutions.

[0006] One of the most salient problems is the need to be able to adapt the amount of hose deployed and thereby how much medium has to circulate and thus has to be heated in the best possible manner relative to the area that has to be thawed. A solution for dividing up a hose length into several smaller parts that can be deployed as required with a special reel and manifold system has therefore been developed according to the present invention. A special solution for operation of the reel for coiling up the hoses is also provided.

[0007] The actual assembly of the various components which together form such a device for thawing frozen ground is problematic, moreover, if the machine has to be built to form a unit that can be placed in a standard container. Maintenance and access to critical components are also important and a solution has therefore been provided for improving this.

[0008] The device according to the present invention preferably employs a glycol-based fluid which is heated and circulated in the hose in order to thaw the ground. Taking into account weight during transport of the device, costs of maintenance and building the device, therefore, it is desirable to have the least possible volume of the glycol-based mixture in the device, and thereby also less glycol-based medium to heat up. A solution for achieving a reduced storage requirement for the glycol mixture has also been developed according to the present invention. This also means reduced heating requirements since there is a smaller volume of the mixture to be maintained at a specific temperature.

[0009] In order to be able to achieve a correct, suitable temperature, regardless of how great a heat supply is necessary (this will vary throughout the thawing process depending on the temperature drop in the heating medium), a solution has therefore been provided that ensures flexible control of heat and temperature supplied and the amount of medium circulated in the hose and the device.

[0010] Amongst previously known solutions, we find in US 5181655 a mobile heating system for thawing frozen ground. The system includes a hot water heater, a tank for antifreeze solution, and a pump mounted on a mobile apparatus which may be a trailer that can be attached to a car or lorry. A hose is fastened to the tank of antifreeze solution, and is also fastened to a heating pod that is inserted in the ground beside frozen water or sewage pipes in order to perform thawing of the ground. The ground is thawed by circulating the hot fluid through the pods. Alternatively, the pods can be used for heating up building material such as bricks.

[0011] Furthermore, in US 5820301 a solution is described for thawing frozen ground to enable concrete to be laid over the ground. This is done by laying a continuous hose on the ground on the inside and/or beside a concrete form or over the ground where the concrete is to be laid. The hoses are then covered by an insulating material, thereby thawing the ground. The insulating material is then removed and the concrete is laid on the hoses. The heat from the hoses prevents the concrete from freezing under cold temperature conditions.

[0012] US 5567085 also describes a solution for curing concrete in the same way as US 5820301.

[0013] US 5707179 describes a method and an apparatus for optimising curing of concrete in extreme temperature conditions. The apparatus consists of a grid-system of plastic hoses which in turn are connected to a system that controls the temperature of the fluid pumped through the system. Two manifolds are placed on each side of the area where the concrete is to be poured, hoses are placed between the manifolds which in turn are connected to a unit that circulates hot fluid in the hose system. After the work is completed, the hoses are cut with the result that they are left lying under or in the concrete.

[0014] US 5449113 describes a heating pod where hot water is circulated which is a part of a mobile heating system.

[0015] US 6761135 describes a mobile heating system in combination with a high-pressure hose. US 6325297 describes a mobile heating unit with a special manifold solution, partially similar to US 6227453. A highly detailed plant for mobile heating is further described in US 5964402. An additional solution where the heating is carried out through a heat exchanger between exhaust and water, where the exhaust comes from a combustion engine for operation of the plant is described in US 5838880.

[0016] CA 1158119 also describes a general circulation system for such plants.

[0017] The present invention is a further development of the known technology and is composed of a number of solutions which together provide a greatly improved product.

[0018] According to the present invention, therefore, a device is provided for thawing frozen ground or heating an area of ground, which device substantially comprises a container for storing a heating medium that is to circulate in a hose deployed for heating the ground, a boiler with a burner for heating the heating medium, which boiler is connected to the container for storing the heating medium, a pump for circulating the heating medium, a hose placed on the ground that is to be heated, through which hose the heating medium circulates, which pump is mounted between the hose and the container for storing the heating medium and which pump circulates the heating medium in the hose. The device further comprises a reel for storing the hose in an inactive state. This is in accordance with the prior art. The known solutions, however, have the disadvantage that a whole hose length has to be uncoiled and filled with heated medium regardless of the size of the area that is to be heated. The individual elements in the device, moreover, are placed near one another and connected to fluid connections such as pipes or electrical connections by cables. The present invention solves this and the other above-mentioned problems by the container for the heating medium, the boiler with burner, the reel and the pump being secured to a common framework construction. This provides a number of opportunities for adapting the size and shape of the structure to different purposes and permits easier transport and assembly during production. The framework, for example, may be placed at a correct height during production, with the result that the production work is carried out faster with a better ergonomic position for the fitter and with less likelihood of injury etc. Furthermore, the final product will be easier to maintain since the components are so positioned relative to one another that normal service points are easily accessible. This applies not least to hose reels where the hoses (which lie on the ground when heating or thawing the ground) will be dirty and have to be cleaned by being hosed down when they are wound in on the reel. In the preferred embodiment such a framework construction is made of galvanised steel or another material which is preferably not subject to corrosion. The invention is further characterised in that the hose consists of two or more hose segments. This avoids the need to fill a whole hose length with heating medium that has to be heated if only a small area has to be heated or thawed. It is therefore possible to adapt the hose length to the area that has to be heated and thereby also adapt the amount of heating medium that has to be circulated. It is only the adapted amount of heating medium that has to be heated and circulated. This provides increased flexibility during use as well as improved energy efficiency. If a shorter hose is employed, i.e. only one or two segments, the heating will also be faster since there is a smaller amount of heating medium that has to be heated in the boiler. An adaptation of this kind where the hose is divided into two or more segments is possible since the invention is also characterised in that the hose segments in an inactive state (when not deployed for heating the ground) are coiled up on a substantially corresponding number of reel segments of a reel, where each hose segment can be selectively connected to the pump via a branch manifold mounted between the pump and each of the hose segments. The manifold is essential and the various hose segments can be coupled into the circuit of circulating heating fluid through valves and/or releasable couplings (quick release couplings).

[0019] The result is a solution where only the necessary segments of the hose are deployed from the reel and connected to the manifold solution, with the result that only the necessary part of the hose is filled with heating medium. This reduces the heating requirement and the heat loss, thereby reducing the operating costs, while making the solution easier to use and capable of being adapted to the individual heating requirement. Furthermore, only the necessary amount of hose is uncoiled from the reel, thus facilitating maintenance etc. since the hose is exposed to external influence from sand/gravel etc. and has to be hosed down when it is coiled up.

[0020] In different embodiments of the invention a fuel tank containing fuel for the burner in the boiler may be secured to the framework construction, which fuel tank is connected to the burner in the boiler. Alternatively, the fuel tank may be mounted separately beside the device and the fuel tank is connected to the burner by a releasable connection.

[0021] In different embodiments of the invention the volume in the coiled hose may be substantially larger than the volume in the storage tank for the heating medium.
This is a result of the fact that the heating medium is left in the hose when it is coiled up on the reel and the need for storage (the storage container for heating medium) is thereby greatly reduced. In a practical embodiment the ratio between the volume of heating medium in the container and the volume of heating medium in the hose (left in the hose, thereby reducing the container size) is 1:3.9. This ratio may vary according to how large the device has to be and which capacity it is to have. The ratio, however, is preferably as high as possible, preferably higher than 1:2 and usually 1:5 where all ratios between this and ratios higher than 1:5 are possible. A lower ratio than 1:2 is also possible but not as favourable.

[0022] The device according to the present invention works by the heating medium in the container and the hose being circulated through the boiler. The burner is located as a separate unit in the boiler and burns fuel from the fuel tank to heat the heating medium in the boiler. The exhaust gas from the burner may also preferably be used in this heating process before being released through the boiler. Furthermore, when the heating medium has reached its correct temperature (it may vary between different applications according to requirements), the heating medium is circulated in such a manner that the device according to the invention fulfils its task of thawing or heating an area. During this "operational phase" the burner in the boiler supplies heat only in relation to the heat loss to which the heating medium is subjected. This heating can be controlled in several ways through pump speed or heat supplied from the burner (by controlling the rate of fuel supplied to the burner). The fuel is preferably diesel.

[0023] In a highly advantageous embodiment the pump speed can be regulated in order to adapt the circulation (the speed and the amount) and the heating (speed through the boiler and amount of fuel supplied to the burner) in relation to the heat loss and the temperature requirement for the heating medium in the hose. If the outer temperature is low and the heat requirement is high (the device is used for thawing deep ground frost on a cold winter's day), the circulation must be adapted so as to prevent the temperature from becoming too low in the heating medium and the supply of heat to the heating medium must also be adapted. The speed regulation of the pump is critical in such cases and provides high efficiency during use (shorter working time on site) and better fuel economy for heating. The circulating medium is subjected to a heat loss through the hose which must be controlled in order to achieve optimal operating conditions. This is possible with speed regulation of the pump. When the pump speed is reduced, less heat is supplied to the heating medium, which is advantageous where there is a small amount of heat loss and the opposite when the heat loss is substantial. The pump should also preferably have a large enough capacity to permit the machine to be located lower in the terrain than the actual workplace where the hose is deployed. At the same time this permits the heating medium to be pumped vertically in order to thaw or remove rime on a vertical or approximately vertical surface such as, for example, shuttering for pouring concrete.

[0024] In a further embodiment which is preferred, a hydraulic motor is employed for rotation of the reel. This may be connected to the circuit with the heating medium so that the pump for circulation of the heating medium drives the hydraulic motor for rotation of the reel. This saves a large amount of installation costs by abolishing the need for a separate unit for operation of the reel (electrical or separate hydraulic unit).

[0025] In a further embodiment for regulating the heat supply in order to achieve the correct temperature relative to requirements, heat loss and the best possible energy economy, the device may be provided with a temperature-sensitive switch which regulates the level of the burner or switches it off and on to control the heating of the heating medium.

[0026] As an additional embodiment there may be an extra outlet on the fuel tank for connection to a unit driven by a combustion engine for production of electricity. This provides good flexibility.

[0027] The fuel tank, moreover, may preferably be mounted in the immediate vicinity of the container for the heating fluid. When the heating fluid is heated up by means of the boiler and the burner, the fuel tank will thereby be heated and an advantageous preheating of the fuel, which will particularly be diesel, is obtained for operation of the burner, for example, and possibly the unit. Preheating of diesel is particularly advantageous under cold conditions (where a device according to the present invention is to be employed) and at very low temperatures preheating is absolutely necessary. Preheating of diesel, moreover, provides better fuel economy since a diesel engine gives a better performance/consumption ratio with preheated diesel. There is preferably a small air gap between the fuel tank and the container for heating medium. Alternatively, the fuel tank may be placed in the immediate vicinity of the boiler, possibly with a fire-preventive or flame-retardant spacer. This solution is entirely dependent on the various structural elements being mounted in a framework construction, which is a fundamental feature of the device according to the present invention.

[0028] A further aspect of the present invention is a device for thawing frozen ground or heating an area of ground, which device substantially comprises a container for storing a heating medium that has to circulate in a hose deployed for heating the ground, a boiler with a burner for heating the heating medium, which boiler is connected with the container for storing the heating medium, a pump for circulating the heating medium, a hose placed on the ground that is to be heated, through which hose the heating medium circulates, which pump is mounted between the hose and the container for storing the heating medium and which pump circulates the heating medium in the hose. The device also includes at least one reel for coiling up the hose in an inactive state. According to this aspect the invention is characterised in that the container for the heating medium, the boiler with burner, the reel and the pump are secured on a common framework construction, which framework construction is provided with external brackets and/or supports for placing it on a transport unit. This permits the device according to the present invention to be adapted for a great number of different transport systems. In different embodiments, the transport unit may be a trailer for a car, the transport unit may be a standard transport container where one or two devices according to the invention are placed in the same container. The framework construction is preferably adapted to be able to be lifted by a standard forklift truck. This permits the device to be loaded in a trailer or container and easily recovered for maintenance and inspection or repair. A solution based on a container as transport unit will be highly flexible since it can be transported by ship, trailer, helicopter, etc. The unit can be easily positioned, it is independent of the environment and is supplied with nothing but fuel. The device according to the present invention can therefore be easily transported as required and can work in remote locations or on ships. It is particularly the framework construction for assembling a device according to the present invention that is the key to this.

[0029] As in the case of the preceding aspect of the invention, there are also different embodiments of this device.

[0030] In different embodiments of the invention, a fuel tank containing fuel for the burner in the boiler may be secured to the framework construction, which fuel tank is connected with the burner in the boiler. Alternatively, the fuel tank may be separately mounted beside the device and the fuel tank is connected to the burner by a releasable coupling.

[0031] In different embodiments of the invention the volume in the coiled hose may be substantially larger than the volume in the storage tank for the heating medium.
This is a result of the fact that the heating medium is left in the hose when it is coiled up on the reel and the need for storage (the storage container for heating medium) is thereby greatly reduced. In a practical embodiment the ratio between the volume of heating medium in the container and the volume of heating medium in the hose (left in the hose, thereby reducing the container size) is 1:3.9. This ratio may vary according to how large the device has to be and which capacity it is to have. The ratio, however, is preferably as high as possible, preferably higher than 1:2 and usually 1: 5 where all ratios between this and ratios higher than 1:5 are possible. A lower ratio than 1:2 is also possible but not as favourable.

[0032] The device according to the present invention works by the heating medium in the container and the hose being circulated through the boiler. The burner is located as a separate unit in the boiler and burns fuel from the fuel tank to heat the heating medium in the boiler. The exhaust gas from the burner may also preferably be used in this heating process before being released through the boiler. Furthermore, when the heating medium has reached its correct temperature (it may vary between different applications according to requirements), the heating medium is circulated in such a manner that the device according to the invention fulfils its task of thawing or heating an area. During this "operational phase" the burner in the boiler supplies heat only in relation to the heat loss to which the heating medium is subjected. This heating can be controlled in several ways through pump speed or heat supplied from the burner (by regulating the amount of fuel supplied to the burner). The fuel is preferably diesel.

[0033] In a highly advantageous embodiment the speed of the pump can be controlled in order to adapt the circulation (the speed and the amount) and the heating (speed through the boiler and amount of fuel supplied to the burner) in relation to the heat loss and the temperature requirement for the heating medium in the hose. If the outer temperature is low and the heat requirement is high (the device is used for thawing deep ground frost on a cold winter's day), the circulation must be adapted to prevent the temperature from becoming too low in the heating medium and the supply of heat to the heating medium must also be adapted. The speed regulation of the pump is critical in such cases and provides high efficiency during use (shorter working time on site) and better fuel economy for heating. The circulating medium is subjected to a heat loss through the hose which must be controlled in order to achieve optimal operating conditions. This is possible with speed regulation of the pump. When the pump speed is reduced, less heat is supplied to the heating medium, which is advantageous where there is a small amount of heat loss and the opposite when the heat loss is substantial. The pump should also preferably have a large enough capacity to permit the machine to be located lower in the terrain than the actual workplace where the hose is deployed. At the same time this permits the heating medium to be pumped vertically in order to thaw or remove rime on a vertical or approximately vertical surface such as, for example, shuttering for pouring concrete.

[0034] In a further embodiment which is preferred, a hydraulic motor is employed for rotation of the reel. This may be connected to the circuit with the heating medium so that the pump for circulation of the heating medium drives the hydraulic motor for rotation of the reel. This saves a large amount of installation costs by abolishing the need for a separate unit for operation of the reel (electrical or separate hydraulic unit).

[0035] In a further embodiment for regulating the heat supply in order to achieve the correct temperature relative to requirements, heat loss and the best possible energy economy, the device may be provided with a temperature-sensitive switch which regulates the level of the burner or switches it off and on to control the heating of the heating medium.

[0036] As an additional embodiment there may be an extra outlet on the fuel tank for connection to a unit driven by a combustion engine for production of electricity. This provides good flexibility.

[0037] The fuel tank, moreover, may preferably be mounted in the immediate vicinity of the container for the heating fluid. When the heating fluid is heated up by means of the boiler and the burner, the fuel tank will thereby be heated and an advantageous preheating of the fuel, which will particularly be diesel, is obtained for operation of the burner, for example, and possibly the unit. Preheating of diesel is particularly advantageous under cold conditions (where a device according to the present invention is to be employed) and at very low temperatures preheating is absolutely necessary. Preheating of diesel, moreover, provides better fuel economy since a diesel engine gives a better performance/consumption ratio with preheated diesel. There is preferably a small air gap between the fuel tank and the container for heating medium. Alternatively, the fuel tank may be placed in the immediate vicinity of the boiler, possibly with a fire-preventive or flame-retardant spacer. This solution is entirely dependent on the various structural elements being mounted in a framework construction, which is a fundamental feature of the device according to the present invention.

[0038] A device according to the present invention is further illustrated in the attached figures in which:

Fig. 1 is a schematic view of a device according to the invention during use.

Fig. 2 is a perspective view of the construction of a device according to the present invention.

Fig. 3 is a perspective view of a framework construction according to the present invention as illustrated in figure 2.

Fig. 4 illustrates in greater detail the device in figure 1 where the manifold over the reel can be seen more clearly.

[0039] In figure 1 a device 1 according to the present invention is illustrated schematically with a hose 2 (supply and return) which is deployed on an area of the ground that has to be heated or thawed. As can be seen, the hose 2 is placed in loops on the ground and the hose is covered by one (or more) insulating mats 3. In this embodiment the hoses are kept in place by straps A This is not a common embodiment and is only shown as an illustration. In the preferred and most usual embodiment straps are not used.

[0040] Furthermore, in figure 2 an embodiment of a device according to the present invention is illustrated, where the hose is not coiled up on the reel or depicted in any other way. The device 1 comprises a fuel tank 9 with an extra outlet (not shown) for connection to a unit or the like. There is further illustrated a container 4 for heating medium which is preferably a glycol-based fluid mixture. The container 4 for the heating medium has a fluid connection via the pipe 6 to a burner 7 which is mounted in a boiler 8 which heats up the heating medium. The container 4 and the fuel tank 9 are placed in the immediate vicinity of each other according to an aspect of the invention. The container 4 is further connected to the boiler 8, thus enabling the heating medium to flow from the container 4 into the boiler 8. The container 4 is therefore a part of the circuit for the heating fluid and also acts as an expansion chamber if the medium expands as a result of the heating. On the container 4, moreover, there is mounted a pressure valve 5 for the release of overpressure if this should be necessary. The valve 5 is preset relative to the upper limit for desirable pressure in the unit.

[0041] Furthermore, there is a connection 10 for heating medium from the boiler, after it has been heated up, which leads to a pump 11 driven by a motor (not shown). This motor may be electrically connected to the external power grid or connected to a combustion engine with a generator. A combustion engine of this kind may use fuel from the fuel tank 9. The pump further supplies pressurised medium in the pipe connection 12 that is connected to the manifold (not shown) under the switch and control panel 13. In this manifold the heating medium from the pump 11 can be distributed to three different hoses that can be coiled up on the reel segments on the reel 14. Underneath the switch and control panel 13 above the manifold are illustrated three sets of couplings 16 for hoses (supply and return) which are to be deployed for thawing or heating the ground. Each of these hoses can be coiled up on their respective reel sections. Through the manifold each individual hose can be connected to the circulation pump 11 and form part of the heating circuit or loop that thaws the ground where the hose is deployed.

[0042] In figure 2 there is further illustrated a hydraulic motor 15 which may be employed for rotating the reel 14. The motor 15 may be connected to the circuit of heating medium that is used as a propellant for the hydraulic motor 11.

[0043] The different components are furthermore mounted on a framework construction 17. This is adapted to be able to be lifted by an ordinary forklift truck and can be placed in a trailer for a car or in a standard cargo container.

[0044] Figure 3 is a perspective view of a framework construction for mounting the various elements in the device according to the present invention. The framework construction 17 comprises a right and left frame side beam 18a and 18b respectively. According to the invention the framework construction 17 is provided with brackets or supports 19 on the right and left frame side beams 18a and 18b. These brackets/supports permit the framework construction and thereby the device according to the present invention to be placed on a transport unit such as a trailer or in a container.

[0045] Furthermore, as illustrated in figure 3, brackets 22 are mounted for a container for heating medium on each of the frame side beams and similarly brackets 22 for the boiler and/or the container for heating fluid. The brackets 22 are further mounted on transverse stiffeners in the framework construction. Moreover, the ends 20 of the framework construction's frame side beams 18a and 18b are adapted to be able to be lifted by an ordinary forklift truck as mentioned above in the general part of the text.

[0046] The frame side beams 18a and 18b, moreover, are provided with rails 21 for mounting the reel for coiling up the hose(s) employed for heating the ground. These rails are preferably mounted at an end where a forklift truck can lift the device and the brackets 19 are also preferably mounted near this part of the device since the reel with hose, containing the body of the heating medium represents a mass concentration and a centre of gravity in the construction.

[0047] Figure 4 illustrates in greater detail the embodiment of the invention in figure 1 where the manifold for distribution of heating medium to the various hose segments is clearly shown.

[0048] As in the case of the device in figure 2, the connection 12 from the pump is the ingoing connection to the manifold's single duct 24 where the heating medium is pumped out (supply) to the hose segments on the reel (not shown). This connection is branched to three different hose connections 16a with valves 26. The return connection from the hose segments is implemented through the connections 16b into the return connection 23 of the manifold with flow meter 25. The return connection 28 to the container 4 for heating medium is further illustrated along the side of the device in connection with the return connection 23 in the manifold.

[0049] A change-over valve 27 is further illustrated that permits connection between the pipe 12 from the pump and the hydraulic motor 15 that rotates the reel. The change-over valve 27 switches between bringing the heating medium from the pump to the manifold for the hose or to the hydraulic motor 15 respectively. The pump 11 can thereby be employed for driving the hydraulic motor 15 thus causing the reel to rotate for winding or unwinding the hose(s) on to or off the reel. There is further illustrated an operating device 29 for a valve that regulates the speed of the motor 15 and thereby also the rotation speed of the reel 14.

[0050] Each of the hose segments is therefore connected in a loop with a supply coupling 16a and a return coupling 16b to the manifold comprising the supply connection 24 and the return connection 23 for each hose segment, thus enabling each hose segment to be separately connected to the manifold. The through-flow in each of the loops may further be regulated by a valve 26. Thus it is possible to achieve different through-flow in each of the segmented hoses and thereby different heating of the ground where each hose is placed. Figure 4 further illustrates an instrument 25 for reading the flow in each of the hose loops.

[0051] This permits each hose segment to be employed separately for heating the ground in a highly flexible manner Furthermore, it is only those hoses that are connected to the circuit of heating medium that are heated and according to requirements this can provide substantial savings in operating costs as well as offering a highly flexible solution.

Claims

1. A device for thawing frozen ground or heating an area of ground, which device substantially comprises a container for storing a heating medium that is to circulate in a hose deployed for heating the ground, a boiler with a burner for heating the heating medium, which boiler is connected to the container for storing the heating medium, a pump for circulating the heating medium, a hose placed on the ground that is to be heated, through which hose the heating medium circulates, which pump is mounted between the hose and the container for storing the heating medium and which pump circulates the heating medium in the hose and at least one reel for storing the hose in an inactive state,
characterised in that

- the container for the heating medium, the boiler with burner, the reel and the pump are secured on a common framework construction,

- the hose consists of two or more hose segments,

- the hose segments are in an inactive state (when not deployed for heating the ground), coiled up on a substantially corresponding number of reel segments of the reel, where each hose segment can be selectively connected with the pump via a branch manifold mounted between the pump and each of the hose segments.

2. A device according to claim 1,
characterised in that a fuel tank containing fuel for the burner in the boiler is fixed to the framework construction, which fuel tank is connected to the burner in the boiler.

3. A device according to claim 1,
characterised in that a free-standing fuel tank containing fuel for the burner in the boiler is releasably connected to the burner in the boiler.

4. A device according to any of the claims 1-3,
characterised in that the volume in the coiled-up hose is substantially greater than the volume in the storage tank for the heating medium.

5. A device according to any of the claims 1-4,
characterised in that the pump's speed can be regulated in order to adapt the through-flow relative to the heat loss and the temperature requirement during circulation of heating medium in the hose.

6. A device according to any of the claims 1-5,
characterised in that a hydraulic motor for rotation of the reel can be connected to the circuit with the heating medium, with the result that the pump for circulation of the heating medium drives the hydraulic motor for rotation of the reel.

7. A device according to any of the claims 1-6,
characterised in that the device is provided with a temperature-sensitive switch which regulates the level of the burner or screws it off and on in order to control the heating of the heating medium.

8. A device according to any of the claims 1-7,
characterised in that there is an extra outlet on the fuel tank for connection to a unit driven by a combustion motor for production of electricity.

9. A device according to any of the claims 1-8,
characterised in that the fuel tank is mounted in the immediate vicinity of the container for the heating fluid.

10. A device according to any of the claims 1-9,
characterised in that the fuel tank is mounted in the immediate vicinity of the boiler.

11. A device for thawing frozen ground or heating an area of ground, which device substantially comprises a container for storing a heating medium that is to circulate in a hose deployed for heating the ground, a boiler with a burner for heating the heating medium, which boiler is connected to the container for storing the heating medium, a pump for circulating the heating medium, a hose placed on the ground that is to be heated, through which hose the heating medium circulates, which pump is mounted between the hose and the container for storing the heating medium and which pump circulates the heating medium in the hose and at least one reel for storing the hose in an inactive state,
characterised in that

- the container for the heating medium, the boiler with burner, the reel and the pump are secured on a common framework construction, which framework construction is provided with external brackets and/or supports for placing it on a transport unit.

12. A device according to claim 11,
characterised in that the transport unit is a trailer for a car.

13. A device according to claim 11,
characterised in that the transport unit is a standard transport container.

14. A device according to claims 11-13,
characterised in that the framework construction is adapted to be able to be lifted by a standard forklift truck.

15. A device according to claims 11-14,
characterised in that a fuel tank containing fuel for the burner in the boiler is fixed to the framework construction, which fuel tank is connected to the burner in the boiler.

16. A device according to claims 11-14,
characterised in that a free-standing fuel tank containing fuel for the burner in the boiler is in releasable connection with the burner in the boiler.

17. A device according to any of the claims 11-16,
characterised in that the volume in the coiled-up hose is substantially greater than the volume in the storage tank for the heating medium.

18. A device according to any of the claims 11-17,
characterised in that the pump's speed can be regulated in order to adapt the through-flow relative to the heat loss and the temperature requirement during circulation of heating medium in the hose.

19. A device according to any of the claims 11-18,
characterised in that a hydraulic motor for rotation of the reel can be connected to the circuit with the heating medium, with the result that the pump for circulation of the heating medium drives the hydraulic motor for rotation of the reel.

20. A device according to any of the claims 11-19,
characterised in that the device is provided with a temperature-sensitive switch which regulates the level of the burner or screws it off and on in order to control the heating of the heating medium.

21. A device according to any of the claims 11-20,
characterised in that there is an extra outlet on the fuel tank for connection to a unit driven by a combustion motor for production of electricity.

22. A device according to any of the claims 11-21,
characterised in that the fuel tank is mounted in the immediate vicinity of the container for the heating fluid.

Drawing